WO2013080514A1 - Optical film, method for producing same, polarizing plate and liquid crystal display device - Google Patents
Optical film, method for producing same, polarizing plate and liquid crystal display device Download PDFInfo
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- WO2013080514A1 WO2013080514A1 PCT/JP2012/007578 JP2012007578W WO2013080514A1 WO 2013080514 A1 WO2013080514 A1 WO 2013080514A1 JP 2012007578 W JP2012007578 W JP 2012007578W WO 2013080514 A1 WO2013080514 A1 WO 2013080514A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
- C08L33/10—Homopolymers or copolymers of methacrylic acid esters
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/16—Optical coatings produced by application to, or surface treatment of, optical elements having an anti-static effect, e.g. electrically conducting coatings
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/49—Phosphorus-containing compounds
- C08K5/51—Phosphorus bound to oxygen
- C08K5/52—Phosphorus bound to oxygen only
- C08K5/521—Esters of phosphoric acids, e.g. of H3PO4
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/08—Cellulose derivatives
- C08L1/10—Esters of organic acids, i.e. acylates
- C08L1/14—Mixed esters, e.g. cellulose acetate-butyrate
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/14—Protective coatings, e.g. hard coatings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
Definitions
- the present invention relates to an optical film, a manufacturing method thereof, a polarizing plate, and a liquid crystal display device.
- Liquid crystal display devices are widely used as liquid crystal displays for televisions and personal computers.
- the liquid crystal display device includes a liquid crystal cell, a pair of polarizing plates sandwiching the liquid crystal cell, and a backlight.
- the polarizing plate usually has a polarizer and a pair of protective films that sandwich the polarizer.
- the polarizing plate and the liquid crystal cell are bonded together with an adhesive. At that time, if a bonding error occurs, the polarizing plate may be peeled off from the liquid crystal cell and reattached. However, when the polarizing plate is peeled off from the liquid crystal cell, there is a problem that the polarizing plate is easily torn. Therefore, the protective film constituting the polarizing plate is required to be able to be easily peeled off without tearing the polarizing plate from the liquid crystal cell when a bonding error occurs (good reworkability). .
- cellulose ester films with adjusted water absorption modulus for example, Patent Document 1
- cellulose ester films with adjusted tan ⁇ for example, Patent Document 2
- acyl group substitution degree are adjusted.
- a film containing cellulose ester for example, Patent Document 3
- a pressure-sensitive adhesive composition containing a (meth) acrylic resin and a crosslinking agent for example, Patent Document 4
- Patent Document 4 has been proposed as a pressure-sensitive adhesive for bonding a polarizing plate and a liquid crystal cell and improving reworkability. Yes.
- the protective film not only a film mainly composed of cellulose ester but also a film mainly composed of (meth) acrylic resin is used depending on the required optical properties.
- a molding material containing a (meth) acrylic resin as a main component for example, a resin composition containing a (meth) acrylic resin and an alkyl phosphate metal salt is known (for example, Patent Document 5).
- the film mainly composed of (meth) acrylic resin is harder and more brittle than the film mainly composed of cellulose ester as described in Patent Documents 1 to 4. Therefore, the polarizing plate including a film containing a (meth) acrylic resin as a main component has a problem that when it is peeled off from the liquid crystal cell once bonded, it is easily torn and has low reworkability.
- the protective film is required to be thinner.
- a protective film having a thin film thickness has a problem that reworkability is further lowered because of its low mechanical strength.
- the (meth) acrylic resin film is usually produced by a melt film forming method. Therefore, in order to increase the flexibility of the (meth) acrylic resin film, it is effective to increase the melting temperature and increase the fluidity of the molten resin. However, when the melting temperature is increased, there is a problem that the molten resin is easily deteriorated, and the resulting film is colored, is brittle and has low flexibility, or does not satisfy desired optical characteristics.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an optical film containing a (meth) acrylic resin as a main component, having no coloring, a thin film thickness, and excellent reworkability. To do.
- An optical film comprising a composition containing a (meth) acrylic resin and an acid trapping agent, having a breaking stress of 70 MPa or more, a tear strength of 10 mN or more, and a film thickness of 10 to 45 ⁇ m. .
- a polarizing plate protective film comprising the optical film according to any one of [1] to [8].
- the polarizing plate protective film according to [9] which is defined by the following formula and has a thickness direction retardation Rth measured at a wavelength of 590 nm of ⁇ 5 nm to 5 nm.
- a polarizing plate comprising a polarizer and the polarizing plate protective film according to [9] or [10] disposed on at least one surface of the polarizer.
- a liquid crystal display device comprising a liquid crystal cell and the polarizing plate according to [11] disposed on at least one surface of the liquid crystal cell.
- an optical film that contains (meth) acrylic resin as a main component, is not colored, has a thin film thickness, and has excellent reworkability.
- optical film of this invention contains the composition containing a (meth) acrylic resin and an acid trap agent.
- the composition preferably further contains a cellulose ester.
- the (meth) acrylic resin is preferably a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another copolymerizable monomer.
- the content ratio of the structural unit derived from methyl methacrylate in the copolymer is preferably 50% by mass or more, and more preferably 70% by mass or more.
- copolymer monomers in the copolymer include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl portion; alkyl acrylates having 1 to 18 carbon atoms in the alkyl portion; hydroxyl groups that can form a lactone ring structure described later.
- Alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl moiety Alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl moiety; ⁇ , ⁇ -unsaturated acids such as acrylic acid and methacrylic acid; unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid and itaconic acid
- Aromatic vinyl compounds such as styrene and ⁇ -methylstyrene
- ⁇ , ⁇ -unsaturated nitriles such as acrylonitrile and methacrylonitrile
- N-vinylpyrrolidone (VP) and the like are included . These may be used alone or in combination of two or more.
- methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate are used to improve the thermal decomposition resistance and fluidity of the copolymer.
- Alkyl (meth) acrylates having a hydroxyl group such as methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate are preferred.
- acryloylmorpholine and the like are preferable.
- the (meth) acrylic resin preferably contains a lactone ring structure from the viewpoint of enhancing the heat resistance of the resulting optical film or adjusting the photoelastic coefficient.
- the lactone ring structure contained in the (meth) acrylic resin is preferably represented by the following general formula (1).
- R 1 to R 3 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.
- the organic residue may contain an oxygen atom.
- Examples of organic residues include linear or branched alkyl groups, linear or branched alkylene groups, aryl groups, —OAc groups (Ac is an acetyl group), —CN groups, and the like.
- the lactone ring structure represented by the formula (1) is a structure derived from an alkyl (meth) acrylate having a hydroxyl group, as will be described later.
- the (meth) acrylic resin containing a lactone ring structure further includes a structural unit derived from an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl portion, and if necessary, a monomer containing a hydroxyl group, an unsaturated carboxylic acid
- a structural unit derived from an acid, a monomer represented by the general formula (2), or the like may be further included.
- R 4 in the general formula (2) represents a hydrogen atom or a methyl group.
- X is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, —OAc group (Ac: acetyl group), —CN group, acyl group, or —C—OR group (R is a hydrogen atom or 1 to 20 organic residues).
- the content ratio of the lactone ring structure represented by the formula (1) in the (meth) acrylic resin containing a lactone ring structure is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, More preferably, it is 15 to 70% by mass.
- the content of the lactone ring structure is more than 90% by mass, the molding processability is low, and the flexibility of the obtained film tends to be low.
- the content of the lactone ring structure is less than 5% by mass, it is difficult to obtain a film having a necessary retardation, and heat resistance, solvent resistance, and surface hardness may not be sufficient.
- the content of the structural unit derived from the alkyl (meth) acrylate is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, Preferably, the content is 30 to 85% by mass.
- the content ratio of the structural unit derived from the hydroxyl group-containing monomer, the unsaturated carboxylic acid, or the monomer represented by the general formula (2) is preferably independently from 0 to 30. % By mass, more preferably 0 to 20% by mass, and still more preferably 0 to 10% by mass.
- the (meth) acrylic resin containing a lactone ring structure is obtained by polymerizing a monomer component containing at least an alkyl (meth) acrylate having a hydroxyl group and another alkyl (meth) acrylate to form a hydroxyl group in the molecular chain. It can be produced through a step of obtaining a polymer having an ester group; a step of introducing a lactone ring structure by heat-treating the obtained polymer.
- the weight average molecular weight Mw of the (meth) acrylic resin is preferably in the range of 8.0 ⁇ 10 4 to 5.0 ⁇ 10 5 , more preferably 9.0 ⁇ 10 4 to 4.5 ⁇ 10 5 . Within the range, more preferably within the range of 1.0 ⁇ 10 5 to 4.0 ⁇ 10 5 . If the weight average molecular weight Mw of the (meth) acrylic resin is less than 8.0 ⁇ 10 4 , the resulting film may be too brittle, and if it exceeds 5.0 ⁇ 10 5 , the viscosity of the melt It is too high or the resulting film has a high haze.
- the weight average molecular weight Mw of the (meth) acrylic resin can be measured by gel permeation chromatography.
- the measurement conditions are as follows. Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK) Column temperature: 25 ° C Sample concentration: 0.1% by mass Detector: RI Model 504 (manufactured by GL Sciences) Pump: L6000 (manufactured by Hitachi, Ltd.) Flow rate: 1.0ml / min
- (Meth) acrylic resin can be produced by a known method such as suspension polymerization, emulsion polymerization, solution polymerization or bulk polymerization.
- the polymerization initiator a normal peroxide compound, azo compound, or redox compound can be used.
- the polymerization temperature can be about 30 to 100 ° C. for suspension polymerization or emulsion polymerization; it can be about 80 to 160 ° C. for solution polymerization or bulk polymerization.
- alkyl mercaptan or the like may be used as a chain transfer agent.
- Examples of commercially available (meth) acrylic resins include Delpet 60N, 80N (Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electricity). Chemical Industry Co., Ltd.).
- (Meth) acrylic resin may be one kind or a mixture of two or more kinds.
- Cellulose ester is a compound obtained by esterifying cellulose with aliphatic carboxylic acid or aromatic carboxylic acid.
- the acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group.
- the aliphatic acyl group may be linear or branched and may further have a substituent. The portion that is not substituted with an acyl group usually exists as a hydroxyl group.
- the cellulose ester has a total acyl group substitution degree (Dall) of 2.0 to 3.0 from the viewpoint of enhancing compatibility with the (meth) acrylic resin or imparting brittleness of the resulting film. Is more preferable, and 2.5 to 3.0 is more preferable.
- the total substitution degree of the acyl group of the cellulose ester is less than 2.0, the (meth) acrylic resin and the cellulose ester may not be sufficiently compatible, and the resulting film may have high haze.
- the substitution degree of the acyl group having 3 to 7 carbon atoms is preferably 1.2 to 3.0, more preferably 2.0 to 3.0.
- the substitution degree of the acyl group having 3 to 7 carbon atoms is less than 1.2, the (meth) acrylic resin and the cellulose ester are not sufficiently compatible with each other, and the resulting film has high haze or high brittleness. Because it does.
- the degree of acyl group substitution can be measured by the method prescribed in ASTM-D817-96.
- cellulose esters examples include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, cellulose butyrate, preferably cellulose acetate propionate, cellulose propionate. It is.
- the weight average molecular weight Mw of the cellulose ester resin is preferably 7.5 ⁇ 10 4 or more from the viewpoint of enhancing the compatibility with the (meth) acrylic resin, and 7.5 ⁇ 10 4 to 2.4 ⁇ 10 5. Is more preferably in the range of 1.0 ⁇ 10 5 to 2.4 ⁇ 10 5 , further preferably in the range of 1.6 ⁇ 10 5 to 2.4 ⁇ 10 5. Particularly preferred.
- the weight average molecular weight Mw is less than 7.5 ⁇ 10 4 , the resulting film has low flexibility and heat resistance may be insufficient.
- the melt has a high viscosity and is difficult to melt and extrude, and has a low compatibility with the (meth) acrylic resin. Haze tends to rise.
- the Tg of the cellulose ester is preferably 100 ° C. or higher, and more preferably 120 ° C. or higher.
- the upper limit of the Tg of the cellulose ester can be about 190 ° C.
- the Tg of cellulose ester can be measured by a method based on JIS K7121.
- Cellulose ester can be synthesized by a known method. Specifically, cellulose is esterified with an organic acid having at least 3 carbon atoms containing acetic acid or an anhydride thereof or an anhydride thereof in the presence of a catalyst to synthesize a triester of cellulose. The cellulose triester is then hydrolyzed to synthesize a cellulose ester resin having the desired degree of acyl substitution. After the obtained cellulose ester resin is filtered, precipitated, washed with water, dehydrated and dried, a cellulose ester resin can be obtained (see the method described in JP-A-10-45804).
- cellulose used as a raw material for example, cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like can be used.
- the cellulose used as a raw material may be only one type or a mixture of two or more types.
- the total content of the (meth) acrylic resin and the cellulose ester in the optical film of the present invention is preferably 55% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass with respect to the optical film. That's it.
- the content ratio of the (meth) acrylic resin is more than 95% by mass with respect to the total of the (meth) acrylic resin and the cellulose ester, the effect due to the cellulose ester is not sufficiently obtained, and is less than 30% by mass, The resulting film may have sufficient heat and humidity resistance.
- the optical film of the present invention may further contain other resins other than the (meth) acrylic resin and cellulose ester as long as the effects of the present invention are not impaired.
- styrene resins include styrene resins.
- the styrenic resin is a homopolymer of styrene monomer (polystyrene), a copolymer of a styrene monomer and another copolymerizable monomer, or a modified product of these polymers, preferably styrene monomer and other It is a copolymer with a copolymerizable monomer.
- the content of the structural unit derived from the styrene monomer in the copolymer is preferably in the range of 0 to 20% by mass.
- Examples of the copolymerizable monomer with the styrene monomer include maleic anhydride, acrylonitrile, maleimide and the like, preferably acrylonitrile.
- the styrene / acrylonitrile copolymer can impart flexibility to a film containing the copolymer.
- composition constituting the optical film of the present invention further contains an acid trap agent.
- the acid trapping agent include alkyl phosphate metal salts and compounds containing an epoxy group.
- the alkyl phosphate metal salt is a metal salt of an alkyl phosphate having 2 to 20 carbon atoms.
- the metal atom constituting the alkyl phosphate metal salt is a Group 2 or Group 12 metal atom, and preferably includes zinc, calcium, magnesium and the like.
- alkyl phosphoric acid having 2 to 20 carbon atoms constituting the alkyl phosphoric acid metal salt examples include ethyl phosphoric acid, butyl phosphoric acid, lauryl phosphoric acid, stearyl phosphoric acid and the like, preferably stearyl phosphoric acid.
- alkyl phosphate metal salts examples include LBT-1830 manufactured by Sakai Chemical.
- Examples of the compound containing an epoxy group include epoxidized vegetable oils such as epoxidized soybean oil, epoxidized linseed oil, epoxidized fatty acid alkyl ester, and epoxidized 1,2 polybutadiene.
- Examples of the epoxidized fatty acid alkyl ester include epoxidized fatty acid octyl ester (Adekasizer D-32 manufactured by Asahi Denka Co., Ltd.), epoxidized fatty acid isobutyl ester (Adekasizer D-55 manufactured by Asahi Denka Co., Ltd.), and the like.
- Examples of the epoxidized 1,2 polybutadiene include Adekasizer BF-1000 (average molecular weight 10,000).
- Examples of the compound containing an epoxy group include compounds containing an epoxy group described in US Pat. No. 4,137,201.
- the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent.
- a resin composition containing a (meth) acrylic resin and an acid trapping agent In order to obtain an optical film having high reworkability; that is, to obtain an optical film having high flexibility, it is effective to increase the resin fluidity by increasing the melting temperature when melt-kneading the resin composition.
- the melting temperature is increased, the monomer remaining in the raw material (meth) acrylic resin is thermally decomposed to generate an acid, or the ester portion of the cellulose ester is hydrolyzed to generate an acid. Acid tends to cause thermal degradation of the resin.
- the acid trapping agent can trap these acids, thermal degradation of the resin can be suppressed even if the melting temperature is increased.
- the content of the acid trapping agent is preferably 0.1% by mass or more, preferably 0.5% by mass or more with respect to the composition in order to suppress thermal decomposition of the resin during melt kneading described later. More preferably, it is more preferably 1.0% by mass or more.
- the content of the acid trapping agent is preferably 5.0% by mass or less.
- the optical film of the present invention further contains additives such as a lubricant, an antioxidant, a thermal degradation inhibitor, an ultraviolet absorber, a colorant, and fine particles (matting agent) as long as the effects of the present invention are not impaired. Also good.
- additives such as a lubricant, an antioxidant, a thermal degradation inhibitor, an ultraviolet absorber, a colorant, and fine particles (matting agent) as long as the effects of the present invention are not impaired. Also good.
- the composition constituting the optical film of the present invention may further contain a lubricant in order to improve transparency and surface quality.
- the lubricant can not only lower the melt viscosity of the resin composition described later and improve the kneadability, but also can suppress the retention of the molten resin in the extruder or the die during the melt extrusion.
- Lubricants can be ester waxes or polyhydric alcohol fatty acid esters.
- Ester waxes are compounds obtained by esterifying all hydroxyl groups of a polyhydric alcohol with a fatty acid.
- Polyhydric alcohol fatty acid esters are compounds obtained by esterifying a part of hydroxyl groups of a polyhydric alcohol with a fatty acid.
- the fatty acid constituting the ester wax or the polyhydric alcohol fatty acid ester has 12 carbon atoms from the viewpoint of suppressing contamination of the process due to volatilization under heating and increasing the compatibility with the cellulose ester.
- a fatty acid of ⁇ 22 is preferred.
- the fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but a saturated fatty acid is preferable from the viewpoint of deodorization and prevention of discoloration during storage.
- saturated fatty acids examples include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, erucic acid, 12-hydroxyoleic acid, etc.
- Stearic acid is preferred.
- One type of fatty acid may be used, or a mixture of two or more types may be used.
- polyhydric alcohols constituting ester waxes or polyhydric alcohol fatty acid esters include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propane Diol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol 1,6-hexanediol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glycerin, diglycerin, galactitol, inositol, mannitol, 3-methylpentane-1,3,5-triol , Nakoru, sorbitol, trimethylol propane, trimethylol ethane, pen
- ester wax examples include pentaerythritol tetrafatty acid ester, dipentaerythritol hexafatty acid ester, glycerin trifatty acid ester and the like.
- Preferred examples of the polyhydric alcohol fatty acid esters include glycerin or diglycerin fatty acid monoester or diester; sorbitol fatty acid monoester, diester or triester; sorbitan fatty acid monoester, diester or triester, more preferably Is fatty acid monoester or diester of glycerin or diglycerin, fatty acid monoester, diester or triester of sorbitan, more preferably glycerin fatty acid monoester.
- ester waxes can reduce friction between the inner wall surface (metal surface) of the extruder, which will be described later, and the molten resin, and can reduce shearing heat generation.
- ester waxes have low compatibility with (meth) acrylic resins and cellulose esters, the effect of lowering the melt viscosity is small, and the resulting film tends to bleed out.
- Polyhydric alcohol fatty acid esters have a smaller effect on reducing the friction between the inner wall (metal surface) of the extruder and the molten resin than ester waxes, but the effect of lowering the melt viscosity is great, so shear heat generation can be reduced. .
- polyhydric alcohol fatty acid esters are highly compatible with (meth) acrylic resins and cellulose esters, the resulting film is less likely to bleed out. Therefore, it is preferable to use polyhydric alcohol fatty acid esters.
- the esterification reaction of ester waxes or polyhydric alcohol fatty acid esters is beef tallow, pork tallow, chicken tallow, fish oil, soybean oil, corn oil, rapeseed oil, palm oil, sunflower oil, safflower oil, castor oil or their hydrogen.
- One or a mixture of two or more of the additive oils and glycerin, diglycerin or sorbitol are subjected to a transesterification reaction, and then the resulting reaction product can be purified.
- the purification method may be a method such as molecular distillation, solvent fractionation, recrystallization, column chromatography, or supercritical gas extraction, and molecular distillation is generally used from the viewpoint of ease of production, quality, and price.
- the content of the ester wax or polyhydric alcohol fatty acid ester is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.0% by mass with respect to the optical film. . If these contents are less than 0.05% by mass, the effect of the lubricant is difficult to obtain, and if the content is more than 2.0% by mass, the heat-and-moisture resistance of the resulting film decreases and the haze increases. Cheap.
- the ultraviolet absorber is a compound that absorbs ultraviolet light having a wavelength of 400 nm or less, preferably a compound having a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% or less, and even more preferably 2% or less. is there.
- the light transmittance of the ultraviolet absorber can be measured with a spectrophotometer by a conventional method using a solution obtained by dissolving the ultraviolet absorber in a solvent (for example, dichloromethane, toluene, etc.).
- the spectrophotometer is, for example, a spectrophotometer UVIDFC-610 manufactured by Shimadzu Corporation, a 330-type self-recording spectrophotometer, a U-3210-type self-recording spectrophotometer, a U-3410-type self-recording spectrophotometer, manufactured by Hitachi, Ltd. -4000 self-recording spectrophotometer or the like can be used.
- Ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic powders, and polymer ultraviolet absorbers.
- benzotriazole-based UV absorbers and benzophenone-based UV absorbers are preferable, and benzotriazole-based UV absorbers are more preferable.
- UV absorbers include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- 6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone and the like are included.
- Examples of commercially available ultraviolet absorbers include TINUVIN109, TINUVIN171, TINUVIN326, TINUVIN327, TINUVIN328, TINUVIN900, TINUVIN928, and LA-31 manufactured by ADEKA Corporation, manufactured by Ciba Japan.
- polymer ultraviolet absorbers examples include polymer type ultraviolet absorbers described in JP-A-6-148430.
- the ultraviolet absorber may be one kind or a mixture of two or more kinds.
- the content of the ultraviolet absorber is preferably 0.5 to 4% by mass, more preferably 0.6 to 3.5% by mass with respect to the optical film, although it depends on the type of the ultraviolet absorber. preferable.
- the composition constituting the optical film of the present invention preferably further contains an antioxidant as a stabilizer.
- antioxidant examples include sulfur compounds, phenol compounds, hindered amine compounds, phosphorus compounds, compounds containing unsaturated double bonds, and the like.
- sulfur compounds examples include Sumitizer TPL-R, Sumilizer TP-D, etc. manufactured by Sumitomo Chemical Co., Ltd.
- phenolic compounds include compounds having a 2,6-dialkylphenol structure (for example, 2,6-di-t-butyl-p-cresol).
- examples of commercially available phenolic compounds include Irganox 1076 and Irganox 1010 manufactured by BASF Japan Ltd.
- Examples of phosphorus compounds include tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite, and the like.
- Examples of commercially available phosphorus compounds include Sumitizer GP manufactured by Sumitomo Chemical Co., Ltd., ADK STAB PEP-24G manufactured by ADEKA Co., Ltd., ADK STAB PEP-36 and ADK STAB 3010, IRGAFOS P-EPQ manufactured by BASF Japan K.K. This includes GSY-P101 manufactured by Kogyo Corporation.
- hindered amine compounds examples include Tinuvin 144 and Tinuvin 770 manufactured by BASF Japan, and ADK STAB LA-52 manufactured by ADEKA.
- Examples of the compound containing an unsaturated double bond include Sumitizer GM and Sumilizer GS manufactured by Sumitomo Chemical Co., Ltd.
- the antioxidant may be only one kind or a mixture of two or more kinds, but is preferably a mixture of two or more kinds.
- the content of the antioxidant is preferably 0.05 to 5% by mass, more preferably 0.1 to 4% by mass with respect to the resin component (total of (meth) acrylic resin and cellulose ester). preferable.
- the composition constituting the optical film of the present invention contains a colorant for imparting bluishness to the color tone of the liquid crystal display screen, adjusting the yellow index (yellowness), and reducing haze. Furthermore, you may contain.
- the colorant include dyes such as anthraquinone dyes and azo dyes, and pigments such as phthalocyanine pigments.
- the composition constituting the optical film of the present invention may further contain fine particles (matting agent) in order to enhance the slipperiness of the surface of the obtained optical film.
- the layer on the outermost surface preferably contains fine particles.
- the fine particles may be inorganic fine particles or organic fine particles.
- inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.
- Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included.
- zirconium oxide fine particles examples include Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.).
- the types of polymers constituting the polymer fine particles include silicone resins, fluororesins, and acrylic resins, preferably silicone resins, and more preferably silicone resins having a three-dimensional network structure.
- Examples of the polymer fine particles include Tospearl 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.).
- Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because the friction coefficient can be reduced while keeping the turbidity of the obtained film low.
- the fine particles are preferably subjected to a surface treatment in order to improve dispersibility and reduce an increase in the haze of the resulting film.
- a surface treatment agent include halosilanes, alkoxysilanes, silazane, siloxane and the like.
- the primary particle diameter of the fine particles is preferably 5 to 50 nm, more preferably 7 to 20 nm.
- a larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter of 0.05 to 0.3 ⁇ m.
- the size of the primary particles or secondary aggregates of the fine particles was determined by observing the primary particles or secondary aggregates at a magnification of 500,000 to 2,000,000 times with a transmission electron microscope, and measuring 100 primary particles or secondary aggregates. It can be determined as an average value of the particle diameter.
- the content of the fine particles is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.8% by mass with respect to the resin component described above.
- the optical film may be a single-layer film made of a composition containing the above-mentioned (meth) acrylic resin and an acid trapping agent; or made of a composition containing the above-mentioned (meth) acrylic resin and an acid trapping agent. It may be a laminated film including layers.
- the thickness of the optical film is not particularly limited, but is preferably 20 to 200 ⁇ m, more preferably 25 to 100 ⁇ m, further preferably 30 to 80 ⁇ m, and more preferably 10 to 45 ⁇ m. It is particularly preferred. If the thickness of the film is too small, it is difficult to obtain a desired retardation. On the other hand, if the thickness of the film is too large, the retardation tends to fluctuate due to the influence of humidity and the like.
- the residual solvent amount of the optical film is preferably 0.01% by mass or less.
- the amount of residual solvent in the optical film can be measured by the following method. 1) Prepare a calibration curve of the solvent used in the optical film production process by the following gas chromatography. 2) 20 ml of a sample obtained by pulverizing the optical film is placed in a sealed glass container and heat-treated under headspace heating conditions. 3) The volatile component obtained by the heat treatment of 2) is quantified by gas chromatography with reference to a calibration curve, and the amount of residual solvent in the optical film is measured. The residual solvent amount is expressed as a part by mass with respect to the total mass of the optical film.
- the breaking stress of the optical film of the present invention under an atmosphere of 23 ° C. and 55% RH is preferably 70 MPa or more, and more preferably 80 MPa or more, in order to enhance the reworkability of the polarizing plate containing the optical film. .
- the breaking stress of the optical film is preferably 200 MPa or less.
- the breaking stress by the following procedure. That is, the optical film is cut into a size of 10 mm ⁇ 150 mm to obtain a sample piece. This sample piece was subjected to a tensile test with a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) at a chuck distance of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min. Let it be stress.
- a tensile tester Strograph-R2 (manufactured by Toyo Seiki)
- the elongation at break in at least one direction measured in accordance with JIS-K7127-1999 of the optical film of the present invention is 30% or more, more preferably 50% or more.
- the upper limit of the elongation at break is practically about 250%.
- the melting temperature is increased, the flexibility of the film is increased, or defects in the film due to foreign matter or foaming are reduced.
- the tear strength of the optical film of the present invention in an atmosphere of 23 ° C. and 55% RH is preferably 10 mN or more, more preferably 20 mN or more in order to improve the reworkability of the polarizing plate containing the optical film. .
- the tear strength of the optical film is preferably 100 mN or less.
- Tear strength can be measured as follows. That is, the optical film is cut into a size of 65 mm ⁇ 50 mm to obtain a sample piece. The tear load of this sample piece by the Elmendorf method is measured with a light load tear device manufactured by Toyo Seiki Co., Ltd. according to JIS K-7128-1991.
- the retardation Ro in the in-plane direction measured at a wavelength of 590 nm under the environment of 23 ° C. and 55% RH of the optical film is preferably in the range of ⁇ 5 nm to 5 nm, and in the range of ⁇ 3 nm to 3 nm. It is more preferable.
- the retardation Rth in the thickness direction is preferably in the range of ⁇ 5 nm to 5 nm, and more preferably in the range of ⁇ 3 nm to 3 nm.
- Retardation R0 and Rth are each represented by the following formula.
- Formula (I) R 0 (nx ⁇ ny) ⁇ d
- Formula (II) Rth ⁇ (nx + ny) / 2 ⁇ nz ⁇ ⁇ d
- Nx refractive index in the slow axis direction in the film plane
- ny refractive index in the direction perpendicular to the slow axis in the film plane
- nz refractive index of the film in the thickness direction
- d film thickness (Nm))
- the retardations R0 and Rth can be determined by the following method, for example. 1) The average refractive index of the film is measured with a refractometer. 2) The retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the normal direction of the film is incident is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments. 3) The retardation value R ( ⁇ ) when light having a wavelength of 590 nm is incident from the angle ⁇ (incident angle ( ⁇ )) with respect to the normal direction of the film is measured with KOBRA-21ADH manufactured by Oji Scientific Instruments. . ⁇ is larger than 0 °, preferably 30 ° to 50 °.
- nx, ny and nz are calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth is calculated.
- the measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.
- the angle ⁇ 1 (orientation angle) formed by the in-plane slow axis of the optical film and the width direction of the film is preferably ⁇ 5 ° or more and + 5 ° or less, and more preferably ⁇ 1 ° or more and + 1 ° or less. .
- the orientation angle ⁇ 1 of the optical film can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).
- the haze of the optical film measured according to JIS K-7136 is more preferably 0.5% or less in order to obtain sufficient brightness and high contrast in a liquid crystal display device, and 0.35% More preferably, it is more preferably 0.05% or less.
- the melting temperature may be increased or the substitution degree of the acyl group having 3 to 7 carbon atoms of the cellulose ester may be increased.
- the haze of the optical film can be measured by a method according to JIS K-7136; specifically, the following method. 1) The obtained optical film is conditioned at 23 ° C. and 55% RH for 5 hours or more. Thereafter, dust attached to the surface of the film is removed with a blower or the like. 2) Next, the haze of the optical film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) under the condition of 23 ° C. and 55% RH.
- the light source of the haze meter may be a 5V9W halogen sphere, and the light receiving part may be a silicon photocell (with a relative visibility filter).
- the visible light transmittance of the optical film is preferably 90% or more, and more preferably 92% or more.
- the optical film of the present invention preferably has no streak-like defects.
- a streak-like defect is a streak extending in the longitudinal direction of the film on the optical film surface, and the height of the streak in the film width direction cross section (height from the top of the streak peak to the bottom of the valley) is 300 nm or more.
- the streak slope is 300 nm / mm or more.
- the shape of the streak defect can be measured by the following procedure. 1) Using Mitutoyo SV-3100S4, film is applied at a measuring speed of 1.0 mm / sec while applying a measuring force of 0.75 mN to a stylus (diamond needle) having a tip shape of 60 ° cone and a radius of curvature of 2 ⁇ m. Scan in the width direction and measure the cross-sectional curve in the film width direction with a Z-axis (thickness direction) resolution of 0.001 ⁇ m. 2) From the obtained cross-sectional curve, the vertical distance (H) between the top of the streak peak and the bottom point of the trough is read and set as the streak height. Also, the horizontal distance (L) between the peak of the mountain and the bottom of the valley is read, and the value obtained by dividing the vertical distance (H) by the horizontal distance (L) is defined as the slope of the stripe.
- the (meth) acrylic resin and cellulose ester contained in the optical film of the present invention are preferably compatible with each other. Whether or not the (meth) acrylic resin and the cellulose ester are compatible can be confirmed by, for example, the glass transition temperature Tg of the optical film. For example, as for the glass transition temperature of the optical film in which the (meth) acrylic resin and the cellulose ester are compatible, the glass transition temperature derived from each resin is not confirmed, and only one glass transition temperature is confirmed.
- the glass transition temperature is measured as a midpoint glass transition temperature (Tmg) by a method based on JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer).
- the heating rate can be 20 ° C./min.
- the optical film of the present invention may further have other functional layers (an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorption layer, a polarizing layer, etc.) as necessary.
- the optical film of the present invention is a polarizing plate protective film, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for widening the viewing angle, etc. for liquid crystal display devices. It can be preferably used.
- the polarizing plate protective film include a protective film further having a retardation adjustment function, an optical compensation function, and the like.
- the optical film of the present invention is a method in which the resin composition containing the (meth) acrylic resin and the acid trapping agent is heated and melted, and then cast and formed (melting film forming method).
- the melt film forming method include a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretch molding method.
- a melt extrusion method is preferred. That is, the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent.
- FIG. 1 is a schematic diagram illustrating an example of a film manufacturing apparatus.
- a film manufacturing apparatus 10 includes an extruder 12 that melts and kneads a resin, a die 14 that discharges the molten resin into a film, and multi-stage cooling of the high-temperature resin discharged from the die 14.
- the extruder 12 is a melt-kneading extruder, and has a cylinder and a screw rotatably provided therein.
- a hopper (not shown) for supplying film material is provided at the supply port of the cylinder.
- the shape of the screw may be full flight, mudock, dull mage, etc., and is selected according to the viscosity of the molten resin and the required shearing force.
- the extruder 12 may be a single screw extruder or a twin screw extruder.
- a filter 28 for filtering the molten resin may be further provided between the extruder 12 and the die 14.
- the filter 28 is, for example, a leaf disk type filter, and is preferably a stainless fiber sintered filter.
- the filtration accuracy of the filter is preferably 3 to 15 ⁇ mm.
- the filter 28 is preferably a multilayer body of filtration media having different filtration accuracy from the viewpoint of increasing the accuracy of capturing foreign substances or gels.
- a mixing device such as a static mixer 30 for uniformly mixing the resin, a gear pump (not shown) for stabilizing the extrusion flow rate, and the like may be further provided. Good.
- the die 14 may be a known one, such as a T die.
- the material of the die 14 body is sprayed or plated with hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc .; buff, It may further be subjected to surface processing such as plane cutting or electrolytic polishing.
- the material of the lip portion of the die 14 can be the same as that of the die body.
- the surface accuracy of the lip portion of the die 14 is preferably 0.5S or less, and more preferably 0.2S or less.
- the slit of the die 14 is configured such that the gap can be adjusted.
- the pair of lips forming the slit of the die 14 one is a flexible lip having low rigidity and is easily deformed, and the other is preferably a fixed lip because the slit gap can be easily adjusted.
- the slit gap (die lip clearance) is preferably 900 ⁇ m or more, and more preferably 1 mm or more and 2 mm or less. When the die lip clearance is out of the above range, spotted unevenness tends to occur in the obtained film.
- the inner wall surface from the extruder 12 to the tip of the die 14 should have a structure in which a resin staying portion is difficult to adhere; for example, from the extruder 12 to the tip of the die 14 It is preferable that the inner wall surface is not scratched.
- the inner wall surfaces of the extruder 12 and the die 14 are preferably subjected to surface processing for reducing the surface roughness or reducing the surface energy in order to make the molten resin difficult to adhere.
- surface processing include processing for polishing to have a surface roughness of 0.2 S or less after hard chrome plating or ceramic spraying.
- the first cooling roll 16, the second cooling roll 18, and the third cooling roll 20 are high-rigidity metal rolls, and have a structure in which a temperature-controllable medium can be circulated.
- the material of the surface of the cooling rolls 16, 18 and 20 can be stainless steel, aluminum, titanium or the like.
- the surface of the cooling rolls 16, 18 and 20 may be subjected to a surface treatment such as hard chrome plating in order to make the resin easy to peel off.
- the surface roughness Ra of the cooling rolls 16, 18, and 20 is preferably 0.1 ⁇ m or less, and more preferably 0.05 ⁇ m or less, in order to keep the haze of the resulting film low.
- the elastic touch roll 32 is disposed to face the cooling roll 16.
- the molten resin extruded from the die 14 is nipped between the cooling roll 16 and the elastic touch roll 32.
- As the elastic touch roll 32 a silicon rubber roll covered with a thin metal sleeve as described in JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096 and the like is used.
- the stretching device 24 is not particularly limited, but a roll stretching machine, a tenter stretching machine or the like is preferably used. A roll stretching machine and a tenter stretching machine may be combined.
- the tenter stretching machine preferably has a preheating zone, a stretching zone, a holding zone, and a cooling zone, and preferably has a neutral zone for insulating between the zones.
- the various rolls in the manufacturing apparatus 10 may be further provided with a mechanism for cleaning the roll surface.
- the roll cleaning method may include a method of niping a brush roll, a water absorption roll, an adhesive roll, a wiping roll, an air blow method of spraying clean air, a laser incineration method, or a combination thereof.
- the optical film of the present invention is, for example, a step of preparing pellets made of the resin composition described above (pelletizing step); It can be obtained through a step of cooling and solidifying the extruded molten resin to obtain a film (cooling and solidifying step); a step of stretching the film (stretching step).
- the resin composition containing the (meth) acrylic resin and the acid trapping agent is previously kneaded and pelletized.
- Pelletization can be performed by a known method.
- the above resin composition is melt-kneaded with an extruder and then extruded from a die in a strand shape.
- the molten resin extruded in a strand shape can be cooled with water or air, and then cut to obtain pellets.
- the ultraviolet absorber or fine particles (matting agent) may be contained in the main pellet made of the above resin composition, or may be contained in a high concentration master pellet different from the above resin composition.
- the raw material of the pellet is preferably dried before being supplied to the extruder in order to prevent decomposition.
- the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more so that the water content is 200 ppm or less, preferably 100 ppm or less.
- the plural types of additives supplied to the extruder may be mixed in advance or may not be mixed.
- a small amount of an additive such as an antioxidant is preferably mixed in advance before being supplied to the extruder in order to mix uniformly.
- the raw materials are preferably mixed with a vacuum nauter mixer.
- the atmosphere near the hopper of the extruder or the exit of the die is preferably an atmosphere of dehumidified air or N 2 gas in order to prevent deterioration of the raw material of the pellet.
- the hopper of the extruder is preferably kept warm to prevent moisture absorption of the raw materials.
- the extruder 12 is preferably kneaded at a low shearing force or at a low temperature so as not to cause deterioration of the resin (decrease in molecular weight, coloring, generation of gel-like foreign matters, etc.).
- a twin screw extruder it is preferable to use a deep groove type screw and to rotate the two screws in the same direction.
- two screw shapes mesh with each other.
- the b * value as an index of yellowness is preferably in the range of -5 to 10, more preferably in the range of -1 to 8, and preferably in the range of -1 to 5. More preferred.
- the b * value can be measured with a spectrocolorimeter CM-3700d (manufactured by Konica Minolta Sensing Co., Ltd.) with a light source of D65 (color temperature 6504K) and a viewing angle of 10 °.
- an optical film may be produced by melting and kneading the resin composition not melt-kneaded as a raw material with the extruder 12 as it is.
- the film material containing pellets is supplied to the extruder 12 from a hopper (not shown).
- the supply of pellets is preferably performed under vacuum, reduced pressure, or an inert gas atmosphere in order to prevent oxidative decomposition of the pellets.
- the film material containing a pellet is melt-kneaded in the extruder 12.
- the melting temperature of the film material in the extruder 12 depends on the type of the film material, the viscosity and discharge amount of the melt, the thickness of the obtained film, etc., but preferably when the glass transition temperature of the film is Tg ° C. It is in the range of Tg ° C. to (Tg + 150) ° C., more preferably in the range of (Tg + 50) ° C. to (Tg + 130) ° C. Specifically, in the case of a (meth) acrylic resin / cellulose ester mixture, the melting temperature is about 150 to 300 ° C, preferably 200 to 270 ° C, more preferably 240 to 270 ° C, The temperature is preferably 260 to 270 ° C. If the melting temperature is too low, the film material may not be sufficiently kneaded, and if the melting temperature is too high, the film material may be thermally deteriorated.
- Highly reworkable optical film Specifically, in order to obtain a highly flexible optical film, it is considered effective to increase the melt temperature and increase the fluidity of the molten resin. However, if the melting temperature is increased, the resin is likely to be thermally deteriorated, so that the resulting film is colored, becomes brittle, or does not satisfy desired optical properties.
- the mechanism of thermal degradation of the resin when the melting temperature is increased is not necessarily clear, but the monomer remaining in the raw material (meth) acrylic resin is thermally decomposed to generate an acid, and this acid is the resin. This is presumed to cause thermal degradation of the material. Thermal degradation of the resin when the melting temperature is increased is particularly likely to occur particularly when the resin composition contains a (meth) acrylic resin and a cellulose ester. It is presumed that the ester portion of the cellulose ester is hydrolyzed to generate an acid, which also causes the resin to thermally deteriorate.
- the resin composition containing a (meth) acrylic resin further contains an acid trapping agent.
- the acid trapping agent can trap an acid that decomposes the resin component, particularly when the melting temperature is increased. Thereby, even if the melting temperature is increased, the resin can be melt-kneaded without causing thermal degradation.
- the melt viscosity of the film material in the extruder 12 is preferably 1 to 10,000 Pa ⁇ s, and more preferably 10 to 1000 Pa ⁇ s. When the melt viscosity of the melt is too high, the pressure rises, so that the residence time in the extruder 12 tends to be long.
- the residence time of the film material in the extruder 12 is preferably short, preferably within about 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes.
- the residence time can be adjusted by the supply amount of the film material, L / D which is the ratio of the cylinder length (L) to the cylinder inner diameter (D), the number of rotations of the screw or the depth of the groove of the screw. .
- the screw rotation speed and shape of the extruder 12 are appropriately selected depending on the melt viscosity and the discharge amount of the film material.
- the shear rate in the extruder 12 is 1 / second to 10,000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second.
- the molten resin extruded from the extruder 12 is filtered with a filter 28 or the like as necessary, and further mixed with a static mixer 30 or the like, and extruded from the die 14 into a film.
- the melting temperature Tm of the resin at the exit portion of the die 14 can be about 200 to 300.degree.
- Cooling and solidifying step The resin extruded from the die is nipped between the cooling roll 16 and the elastic touch roll 32 so that the film-like molten resin has a predetermined thickness. Then, the film-like molten resin is cooled stepwise with a plurality of cooling rolls 18 and 20 and solidified.
- the surface temperature Tr1 of the first cooling roll 16 and the surface temperature Tr2 of the second cooling roll 18 can be independently set to (Tg-50) ° C. or more and Tg or less. Further, Tr2> Tr1 is preferable, and 0 ⁇ Tr2-Tr1 ⁇ 50 is more preferable. This is because by setting Tr2> Tr1, the condensation of the additive on the second cooling roll 18 is suppressed and the film is easily remelted.
- the re-dissolution of the additive into the film can be adjusted by the contact time between the film and the second cooling roll 18, and specifically, it is preferably 1.0 to 3.0 seconds.
- the contact time is a second obtained by dividing the distance between the point where the film and the second cooling roll 18 start to contact and the point where the second cooling roll 18 starts to peel by the film conveyance speed. Is a number.
- the peripheral speed R2 of the second cooling roll 18 is preferably larger than the peripheral speed R1 of the first cooling roll 16. Tension is applied to the film between these two cooling rolls, thereby improving the adhesion between the film and the first cooling roll 16.
- the ratio of the peripheral speeds is preferably in the range of 1.00 to 1.05. If the ratio of the peripheral speeds exceeds 1.05, the film may be broken.
- the peripheral speed of the third cooling roll 20 is preferably larger than the peripheral speed of the second cooling roll 18.
- the draw ratio is preferably 5-30.
- the draw ratio is a value obtained by dividing the lip clearance of the die 14 by the average film thickness of the film obtained by cooling and solidifying on the first, second and third cooling rolls 16, 18 and 20. By setting the draw ratio within the above range, it is easy to obtain a film with few failures that cause bright and dark stripes and spotted unevenness when an image is displayed on a liquid crystal display device.
- the draw ratio can be adjusted by the die lip clearance and the take-up speed of the cooling roll.
- the discharge of the molten resin from the lip (opening) of the die 14 to the surface of the first cooling roll 16 is preferably performed at a reduced pressure of 70 kPa or less, more preferably 50 to 70 kPa. This is because die lines are less likely to occur in the obtained film.
- the method of reducing the pressure between the lip (opening) of the die 14 and the surface of the first cooling roll 16 is, for example, covering the space including the die 14 and the first cooling roll 16 with a pressure-resistant member and reducing the pressure inside the space. There are methods.
- the surface temperature Tr0 of the elastic touch roll 32 is preferably equal to or lower than the glass transition temperature (Tg) of the film, and more preferably Tg-50 ⁇ Tr0 ⁇ Tg. If the surface temperature Tr0 of the elastic touch roll 32 exceeds Tg, the film and the first cooling roll 16 may be difficult to peel off.
- the linear pressure of the elastic touch roll 32 when pressed by the elastic touch roll 32 is 9.8 to 147 N / cm.
- the linear pressure is less than 9.8 N / cm, it is difficult to sufficiently suppress the die line.
- the surface temperature Tt of the film-like molten resin extruded from the die 14 immediately before being nipped by the elastic touch roll 32 is preferably Tg ⁇ Tt ⁇ Tg + 110 ° C., more preferably Tg + 10 ° C. ⁇ Tt ⁇ Tg + 90 ° C., and further preferably Tg + 20 ° C. ⁇ Tt ⁇ Tg + 70 ° C.
- the adjustment of the surface temperature Tt on the elastic touch roll 32 immediately before being nipped by the elastic touch roll 32 of the film-like molten resin shortens the air gap (distance) between the die 14 and the first cooling roll 16. Then, the method of suppressing the cooling between the die 14 and the first cooling roll 16, the method of keeping the temperature between the die 14 and the first cooling roll 16 with a heat insulating material or the method of heating or the like. it can.
- the heating can be heating with hot air, an infrared heater or microwave.
- the film surface temperature and roll surface temperature can be measured with a non-contact infrared thermometer. Specifically, the surface temperature of the film or roll is determined by using a non-contact handy thermometer (IT2-80, manufactured by Keyence Co., Ltd.), the surface temperature at any 10 locations in the width direction of the film or roll, Or it measures at the position 0.5m away from the surface of the roll.
- IT2-80 non-contact handy thermometer
- the film solidified by the cooling rolls 16, 18 and 20 is peeled off by the peeling roll 22.
- peeling the film it is preferable to adjust the tension applied to the film in order to prevent deformation.
- Stretching step The obtained film is stretched by a stretching device 24 to obtain an optical film.
- the stretching may be performed in at least one of the width direction of the film (TD direction), the transport direction (MD direction), or the oblique direction, and both in the film width direction (TD direction) and the transport direction (MD direction). It is preferable to stretch.
- stretching in both the width direction (TD direction) and the transport direction (MD direction) of the film stretching in the width direction (TD direction) of the film and stretching in the transport direction (MD direction) may be performed sequentially. You may do it simultaneously.
- the draw ratio may be 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction.
- TD direction width direction
- MD direction conveyance direction
- it is finally 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction. Is preferred.
- the stretching temperature is preferably Tg to (Tg + 50) ° C., more preferably Tg to (Tg + 40) ° C.
- the stretching temperature can be about 100 to 190 ° C.
- the stretching temperature is too high, the tear strength of the obtained optical film is high, but the breaking stress may be low.
- the stretching temperature is too low, the obtained optical film has a high breaking stress but may have a low tear strength.
- the stretching temperature is preferably uniform in the width direction (TD direction) or the transport direction (MD direction) of the film, and the variation in the width direction or transport direction of the film stretching temperature is preferably ⁇ 2 ° C. or less, The temperature is more preferably ⁇ 1 ° C. or less, and further preferably ⁇ 0.5 ° C. or less.
- the film obtained after stretching is shrunk in the transport direction (MD direction) or the width direction (TD direction) as necessary. May be.
- MD direction transport direction
- TD direction width direction
- the distance between adjacent clips in the film transport direction is driven by the pantograph method or linear drive method. Then it should be smooth and narrow.
- the width of the obtained optical film may be 0.5 to 4.0 m, preferably 1.0 to 3.0 m, although it depends on the width of the polarizer.
- the film thickness variation of the optical film is preferably ⁇ 3% or less, and more preferably ⁇ 1% or less.
- knurl processing embossing processing
- the knurling can be performed with a knurling apparatus having an embossing ring and a back roll.
- the optical film thus obtained is wound up by a winder.
- the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent.
- the acid trapping agent contained in this resin composition is produced when the monomer remaining in the (meth) acrylic resin is thermally decomposed and the ester part of cellulose ester is hydrolyzed when the melting temperature is increased. Since the acid can be trapped, the thermal deterioration of the resin can be suppressed. Therefore, it is possible to obtain an optical film that is not colored, satisfies desired optical characteristics, has high flexibility, and has high reworkability.
- Polarizing plate The polarizing plate of the present invention comprises a polarizer and the optical film of the present invention disposed on at least one surface thereof.
- a polarizer is an element that allows only light of a polarization plane in a certain direction to pass through.
- a typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.
- the polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing with iodine or a dichroic dye, or after dyeing a polyvinyl alcohol film with iodine or a dichroic dye, A uniaxially stretched film (preferably a film further subjected to durability treatment with a boron compound) may be used.
- the thickness of the polarizer is preferably 5 to 30 ⁇ m, more preferably 10 to 20 ⁇ m.
- the polyvinyl alcohol film may be a film formed from a polyvinyl alcohol aqueous solution.
- the polyvinyl alcohol film is preferably an ethylene-modified polyvinyl alcohol film because it is excellent in polarizing performance and durability performance and has few color spots.
- Examples of the ethylene-modified polyvinyl alcohol film include an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000, and a degree of saponification of 99.0, as described in JP-A Nos. 2003-248123 and 2003-342322. ⁇ 99.99 mol% film is included.
- dichroic dyes examples include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.
- the optical film of the present invention may be disposed directly on at least one surface of the polarizer, or may be disposed via another film or layer.
- the optical film of the present invention may be disposed on the other surface of the polarizer, or a protective film other than that may be disposed.
- the protective film is not particularly limited, and may be a normal cellulose ester film or the like.
- commercially available cellulose ester films include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4UE, KC4FR-3, KC4FR-4, KC4HR-1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.
- the polarizing plate can be usually obtained through a step of bonding a polarizer and the optical film of the present invention.
- adhesives used for pasting include saponified polyvinyl alcohol aqueous solutions, curable adhesives such as urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, thermosetting acrylic adhesives, etc.
- a fully saponified polyvinyl alcohol aqueous solution is preferable.
- the liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one is a polarizing plate which has an optical film of this invention among a pair of polarizing plates, Preferably both of a pair of polarizing plates are polarizing plates which have an optical film of this invention.
- FIG. 2 is a schematic diagram showing a basic configuration of an embodiment of the liquid crystal display device 110 according to the present invention.
- the liquid crystal display device 110 includes a liquid crystal cell 120, a first polarizing plate 140 and a second polarizing plate 160 that sandwich the liquid crystal cell 120, and a backlight 180.
- the display method of the liquid crystal cell 120 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an IPS (In-Plane Switching) method (including an FFS method), an OCB (OpticallyalCompensating Bensing method).
- VA Vertical Alignment
- MVA Multi-domain Vertical Alignment and PVA; Patterned Vertical Alignment also included
- HAN Hybrid Aligned Nematic
- the first polarizing plate 140 is disposed on the viewing side of the liquid crystal cell 120, and the first polarizer 142 and the protective film 144 (F1) disposed on the viewing side of the first polarizer 142. And a protective film 146 (F2) disposed on the surface of the first polarizer 142 on the liquid crystal cell side.
- the second polarizing plate 160 is disposed on the backlight 180 side, the second polarizer 162, a protective film 164 (F3) disposed on the liquid crystal cell side surface of the second polarizer 162, And a protective film 166 (F4) disposed on the backlight side surface of the second polarizer 162.
- One of the protective films 146 (F2) and 164 (F3) may be omitted as necessary.
- the protective films 144 (F1), 146 (F2), 164 (F3), and 166 (F4) at least one of the protective films 146 (F2) and 164 (F3) arranged on the liquid crystal cell side of the present invention is used.
- An optical film is preferred.
- the size of the liquid crystal display device is preferably 30 or more, more preferably 30 to 54.
- the liquid crystal display device is preferably used also for outdoor applications such as digital signage.
- the liquid crystal display device can be manufactured through a step of bonding a liquid crystal cell and a polarizing plate together with an adhesive.
- the pressure-sensitive adhesive is preferably a curable pressure-sensitive adhesive, and more preferably a curable pressure-sensitive adhesive having a cured elastic modulus at 25 ° C. of 1.0 ⁇ 10 4 to 1.0 ⁇ 10 9 Pa. Examples of such an adhesive include those similar to the above-mentioned curable adhesive.
- the optical film of the present invention is obtained through a step of melt-kneading a resin composition containing an acid trapping agent at a high melting temperature. Therefore, the optical film of the present invention is not colored and has high flexibility (reworkability) while satisfying desired optical characteristics. Therefore, even after the polarizing plate including the optical film of the present invention is once bonded to the liquid crystal cell, it can be easily peeled off from the liquid crystal cell without tearing the polarizing plate. Moreover, the liquid crystal display device containing the optical film of this invention has a favorable display characteristic.
- the obtained mixture was melt-kneaded at 235 ° C. with a twin-screw extruder and extruded into a strand shape.
- the resin composition extruded in a strand form was cooled with water and then cut to obtain pellets.
- an optical film was produced with the film production apparatus 10 shown in FIG.
- the obtained pellets were put into a single screw extruder (extruder 12), and melt kneaded at 260 ° C. in a nitrogen atmosphere. Then, it extruded from the die
- the slit gap of the die 14 was 0.5 mm within 30 mm from the end in the film width direction, and 1 mm at other locations.
- the surface temperature of the elastic touch roll 32 was 80 ° C.
- the film obtained by cooling and solidifying the resin extruded from the die 14 on the first, second and third cooling rolls was peeled off by the peeling roll 22.
- the obtained film was stretched 1.3 times at 145 ° C. in the width direction by a tenter stretching machine, and then cooled to 30 ° C. while relaxing 3% in the width direction.
- the clip was removed, and the portions held by the clips at both ends of the film were cut off, and then knurling with a width of 10 mm and a height of 5 ⁇ m was applied to both ends of the film.
- the obtained film was wound up at a winding tension of 220 N / m.
- the obtained film had a thickness of 40 ⁇ m and a width of 1430 mm, and the glass transition temperature measured by the DSC method was 125 ° C.
- Example 2 An optical film was obtained in the same manner as in Example 1 except that the type of the acid trapping agent or the melting temperature was changed as shown in Table 1.
- Example 5 An optical film was obtained in the same manner as in Example 4 except that the content of the acid trapping agent was changed as shown in Table 1.
- Example 9 to 12 An optical film was obtained in the same manner as in Example 3 except that the content ratio A / B of (A) (meth) acrylic resin and (B) cellulose ester was changed as shown in Table 1.
- Example 15 An optical film was obtained in the same manner as in Example 1 except that the film thickness was changed as shown in Table 3.
- Retardation Rth i) The average refractive index of the film was measured with a refractometer. ii) Retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the film normal direction was incident was measured by KOBRA-21ADH manufactured by Oji Scientific Instruments. iii) With KOBRA-21ADH manufactured by Oji Scientific Instruments, the retardation value R ( ⁇ ) was measured when light having a wavelength of 590 nm was incident from the angle ⁇ (incident angle ( ⁇ )) with respect to the film normal direction. . ⁇ was 30 ° to 50 °.
- nx, ny and nz were calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.
- the Rth of the obtained film is preferably ⁇ 3 nm or less.
- the obtained optical film was alkali saponified, then washed with water, neutralized and washed with water. Thereafter, the obtained optical film was dried at 80 ° C. Saponification process 2M-NaOH 50 ° C. 90 seconds Water washing process Water 30 ° C. 45 seconds Neutralization process 10% by mass HCl 30 ° C. 45 seconds Water washing process Water 30 ° C. 45 seconds
- KC4UY manufactured by Konica Minolta Opto Co., Ltd. was also alkali saponified. Then, KC4UY subjected to alkali saponification treatment was bonded to one surface of the above polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. Similarly, an alkali film saponified optical film was bonded to the other surface of the polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. The bonding was performed so that the transmission axis of the polarizer and the in-plane slow axis of the optical film were parallel. The laminated laminate was dried to obtain a polarizing plate.
- n-BA n-butyl acrylate
- MA methyl acrylate
- 2-HEA 2-hydroxy acrylate
- AIBN azobisiso 0.2 parts by mass of butyronitrile
- the obtained pressure-sensitive adhesive composition was applied onto the peeled film so as to have a dry thickness of 25 ⁇ m to form a pressure-sensitive adhesive layer, thereby obtaining a pressure-sensitive adhesive sheet.
- the aforementioned polarizing plate was punched into a size of 100 ⁇ 100 mm.
- the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was transferred to one surface of the obtained polarizing plate to obtain a pressure-sensitive adhesive-attached polarizing plate.
- the polarizing plate with an adhesive was bonded to the glass substrate.
- the polarizing plate was slightly peeled from the glass substrate from one of the four corners, and was peeled diagonally while holding the peeled polarizing plate and holding the glass substrate. The same operation was performed on a total of 10 samples, and evaluation was performed according to the following criteria.
- ⁇ All 10 sheets were able to be completely peeled without tearing.
- ⁇ The optical film was torn with 1 to 5 sheets, and part of the film remained on the glass substrate. Torn and part of it remained on the glass substrate, resulting in peeling residue
- ⁇ Change in total light transmittance is 5% or less.
- ⁇ Change in total light transmittance is more than 5% and 10% or less.
- X Change in total light transmittance is more than 10%. If it is ⁇ level, there is no practical problem.
- the evaluation results of the optical films of Examples 1 to 14 are shown in Table 1, the evaluation results of the optical films of Comparative Examples 1 to 13 are shown in Table 2, and the evaluation results of the optical films of Examples 15 to 16 and Comparative Example 14 are shown.
- Table 4 shows the evaluation results of Comparative Examples 15 to 18.
- the films of Examples 1 to 16 containing LBT1830 or Adekasizer D-32 which are acid trapping agents have higher breaking stress and tear strength than the films of Comparative Examples 1 to 13 containing no acid trapping agent, and are colored. It turns out that it does not occur.
- the films of Examples 1 and 2 formed at a high melting temperature have higher reworkability and no coloration than the films of Examples 3 and 4 formed at a low melting temperature.
- the reason why the films of Examples 1 and 2 were not colored is considered to be that the thermal deterioration of the resin when the melting temperature was increased could be suppressed by containing an acid trapping agent.
- the high reworkability of the films of Examples 1 and 2 is that the fluidity of the resin composition containing (meth) acrylic resin and cellulose ester can be increased by increasing the melting temperature, and the flexibility of the resulting film This is thought to be due to the improvement in performance.
- Example 3 The comparison between Example 3 and 9 to 12 suggests that if the content ratio of the (meth) acrylic resin is too large, the resulting film tends to be slightly brittle and the tear strength tends to decrease slightly. On the other hand, when the content ratio of the cellulose ester is too large, it can be seen that the resulting film is slightly colored.
- the film containing the (meth) acrylic resin containing the lactone ring has higher film strength and higher reworkability than the film containing the (meth) acrylic resin containing no lactone ring.
- the strength of the film containing the (meth) acrylic resin containing the lactone ring is high because the structural units derived from the uncyclized hydroxyl group-containing monomer contained in the main chain of the (meth) acrylic resin containing the lactone ring are hydrogen. It is considered that this is because a bond is formed and the compatibility between the (meth) acrylic resin and the cellulose ester is high.
- Example 16 it can be seen that even a thin film having a film thickness of about 10 ⁇ m has a tear strength of a certain level or more and exhibits good reworkability by including an acid trapping agent.
- the resulting film is colored or the Rth is slightly increased. Since the film of Comparative Example 1 does not contain an acid trapping agent, it is considered that the resin was thermally deteriorated due to a high melting temperature. Moreover, it is considered that the Rth of the film containing the thermally deteriorated resin is high because the side chain of the cellulose ester is decomposed. Moreover, since the film containing the resin which carried out heat deterioration is weak, it turns out that rework property is also low.
- the optical film of the present invention contains (meth) acrylic resin as a main component, is not colored, has a thin film thickness, and is excellent in reworkability.
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Abstract
The purpose of the present invention is to provide an optical film which contains a (meth)acrylic resin as a main component, is free from coloration, and has a thin film thickness and excellent reworkability. An optical film of the present invention contains a composition that contains a (meth)acrylic resin and an acid trapping agent, and has a rupture stress of 70 MPa or more, a tear strength of 10 mN or more and a film thickness of 10-45 μm.
Description
本発明は、光学フィルムとその製造方法、偏光板および液晶表示装置に関する。
The present invention relates to an optical film, a manufacturing method thereof, a polarizing plate, and a liquid crystal display device.
液晶表示装置は、テレビやパソコンなどの液晶ディスプレイとして広く用いられている。液晶表示装置は、液晶セルと、それを挟持する一対の偏光板と、バックライトとを有する。偏光板は、通常、偏光子と、それを挟持する一対の保護フィルムとを有する。
Liquid crystal display devices are widely used as liquid crystal displays for televisions and personal computers. The liquid crystal display device includes a liquid crystal cell, a pair of polarizing plates sandwiching the liquid crystal cell, and a backlight. The polarizing plate usually has a polarizer and a pair of protective films that sandwich the polarizer.
液晶表示装置の製造工程では、偏光板と液晶セルとを、粘着剤を介して貼り合わせている。その際、貼り合わせミスが生じると、偏光板を液晶セルから剥がして再び貼り直すことがある。しかしながら、偏光板を液晶セルから剥がす際に、偏光板が裂けやすいという問題があった。そのため、偏光板を構成する保護フィルムには、貼り合わせミスが生じたときに、偏光板を液晶セルから裂けることなく容易に剥がすことができること(リワーク性が良好であること)が求められている。
In the manufacturing process of the liquid crystal display device, the polarizing plate and the liquid crystal cell are bonded together with an adhesive. At that time, if a bonding error occurs, the polarizing plate may be peeled off from the liquid crystal cell and reattached. However, when the polarizing plate is peeled off from the liquid crystal cell, there is a problem that the polarizing plate is easily torn. Therefore, the protective film constituting the polarizing plate is required to be able to be easily peeled off without tearing the polarizing plate from the liquid crystal cell when a bonding error occurs (good reworkability). .
リワーク性が改善された保護フィルムとして、吸水弾性率が調整されたセルロースエステルフィルム(例えば特許文献1)、tanδが調整されたセルロースエステルフィルム(例えば特許文献2)、およびアシル基置換度が調整されたセルロースエステルを含むフィルム(例えば特許文献3)などが提案されている。また、偏光板と液晶セルとを接着し、かつリワーク性を改善するための粘着剤として、(メタ)アクリル樹脂と架橋剤とを含む粘着性組成物(例えば特許文献4)なども提案されている。
As protective films with improved reworkability, cellulose ester films with adjusted water absorption modulus (for example, Patent Document 1), cellulose ester films with adjusted tan δ (for example, Patent Document 2), and acyl group substitution degree are adjusted. A film containing cellulose ester (for example, Patent Document 3) has been proposed. In addition, a pressure-sensitive adhesive composition containing a (meth) acrylic resin and a crosslinking agent (for example, Patent Document 4) has been proposed as a pressure-sensitive adhesive for bonding a polarizing plate and a liquid crystal cell and improving reworkability. Yes.
ところで、保護フィルムとしては、求められる光学特性に応じて、セルロースエステルを主成分とするフィルムだけでなく、(メタ)アクリル樹脂を主成分とするフィルムも用いられている。(メタ)アクリル樹脂を主成分とする成形材料として、例えば(メタ)アクリル樹脂と、アルキルリン酸金属塩とを含む樹脂組成物が知られている(例えば特許文献5)。
Incidentally, as the protective film, not only a film mainly composed of cellulose ester but also a film mainly composed of (meth) acrylic resin is used depending on the required optical properties. As a molding material containing a (meth) acrylic resin as a main component, for example, a resin composition containing a (meth) acrylic resin and an alkyl phosphate metal salt is known (for example, Patent Document 5).
しかしながら、(メタ)アクリル樹脂を主成分とするフィルムは、特許文献1~4に記載のようなセルロースエステルを主成分とするフィルムよりも、硬くて脆い。そのため、(メタ)アクリル樹脂を主成分とするフィルムを含む偏光板は、一旦貼り合わせた液晶セルから剥がす際に、裂けやすく、リワーク性が低いという問題があった。
However, the film mainly composed of (meth) acrylic resin is harder and more brittle than the film mainly composed of cellulose ester as described in Patent Documents 1 to 4. Therefore, the polarizing plate including a film containing a (meth) acrylic resin as a main component has a problem that when it is peeled off from the liquid crystal cell once bonded, it is easily torn and has low reworkability.
また、液晶表示装置の薄型化に伴い、保護フィルムの膜厚も薄いことが求められている。膜厚が薄い保護フィルムは、機械的強度が低いことから、リワーク性がさらに低いという問題があった。
Also, as the liquid crystal display device becomes thinner, the protective film is required to be thinner. A protective film having a thin film thickness has a problem that reworkability is further lowered because of its low mechanical strength.
このように、膜厚が薄く、かつリワーク性が高い;即ち柔軟性の高い(メタ)アクリル樹脂フィルムが求められている。(メタ)アクリル樹脂フィルムは、通常、溶融製膜法により製造される。そのため、(メタ)アクリル樹脂フィルムの柔軟性を高めるためには、溶融温度を高くして、溶融樹脂の流動性を高めることが有効である。しかしながら、溶融温度を高くすると、溶融樹脂が劣化しやすく、得られるフィルムが着色していたり、脆くて柔軟性が低かったり、所望の光学特性を満たさなかったりするという問題があった。
Thus, a thin film thickness and high reworkability; that is, a highly flexible (meth) acrylic resin film is required. The (meth) acrylic resin film is usually produced by a melt film forming method. Therefore, in order to increase the flexibility of the (meth) acrylic resin film, it is effective to increase the melting temperature and increase the fluidity of the molten resin. However, when the melting temperature is increased, there is a problem that the molten resin is easily deteriorated, and the resulting film is colored, is brittle and has low flexibility, or does not satisfy desired optical characteristics.
本発明は、上記事情に鑑みてなされたものであり、(メタ)アクリル樹脂を主成分として含み、着色がなく、膜厚が薄く、かつリワーク性に優れた光学フィルムを提供することを目的とする。
The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical film containing a (meth) acrylic resin as a main component, having no coloring, a thin film thickness, and excellent reworkability. To do.
[1] (メタ)アクリル樹脂と、酸トラップ剤とを含有する組成物を含み、破断応力が70MPa以上であり、かつ引き裂き強度が10mN以上であり、膜厚が10~45μmである、光学フィルム。
[2] 前記酸トラップ剤が、アルキルリン酸金属塩である、[1]に記載の光学フィルム。
[3] 前記酸トラップ剤の含有量は、前記組成物に対して0.1~5質量%である、[1]または[2]に記載の光学フィルム。
[4] 前記組成物が、セルロースエステルをさらに含有する、[1]~[3]のいずれかに記載の光学フィルム。
[5] 前記セルロースエステルが、セルロースアセテートプロピオネートである、[4]に記載の光学フィルム。
[6] 前記(メタ)アクリル樹脂と前記セルロースエステルの含有比率は、質量比で(メタ)アクリル樹脂/セルロースエステル=90/10~50/50である、[4]または[5]に記載の光学フィルム。
[7] 前記(メタ)アクリル樹脂がラクトン環構造を有する、[1]~[6]のいずれかに記載の光学フィルム。
[8] 前記組成物が、アクリロニトリル・スチレン共重合体をさらに含有する、[1]~[7]のいずれかに記載の光学フィルム。 [1] An optical film comprising a composition containing a (meth) acrylic resin and an acid trapping agent, having a breaking stress of 70 MPa or more, a tear strength of 10 mN or more, and a film thickness of 10 to 45 μm. .
[2] The optical film according to [1], wherein the acid trapping agent is an alkyl phosphate metal salt.
[3] The optical film according to [1] or [2], wherein the content of the acid trapping agent is 0.1 to 5% by mass with respect to the composition.
[4] The optical film according to any one of [1] to [3], wherein the composition further contains a cellulose ester.
[5] The optical film according to [4], wherein the cellulose ester is cellulose acetate propionate.
[6] The content ratio of the (meth) acrylic resin and the cellulose ester is (meth) acrylic resin / cellulose ester = 90/10 to 50/50 by mass ratio, according to [4] or [5] Optical film.
[7] The optical film according to any one of [1] to [6], wherein the (meth) acrylic resin has a lactone ring structure.
[8] The optical film according to any one of [1] to [7], wherein the composition further contains an acrylonitrile / styrene copolymer.
[2] 前記酸トラップ剤が、アルキルリン酸金属塩である、[1]に記載の光学フィルム。
[3] 前記酸トラップ剤の含有量は、前記組成物に対して0.1~5質量%である、[1]または[2]に記載の光学フィルム。
[4] 前記組成物が、セルロースエステルをさらに含有する、[1]~[3]のいずれかに記載の光学フィルム。
[5] 前記セルロースエステルが、セルロースアセテートプロピオネートである、[4]に記載の光学フィルム。
[6] 前記(メタ)アクリル樹脂と前記セルロースエステルの含有比率は、質量比で(メタ)アクリル樹脂/セルロースエステル=90/10~50/50である、[4]または[5]に記載の光学フィルム。
[7] 前記(メタ)アクリル樹脂がラクトン環構造を有する、[1]~[6]のいずれかに記載の光学フィルム。
[8] 前記組成物が、アクリロニトリル・スチレン共重合体をさらに含有する、[1]~[7]のいずれかに記載の光学フィルム。 [1] An optical film comprising a composition containing a (meth) acrylic resin and an acid trapping agent, having a breaking stress of 70 MPa or more, a tear strength of 10 mN or more, and a film thickness of 10 to 45 μm. .
[2] The optical film according to [1], wherein the acid trapping agent is an alkyl phosphate metal salt.
[3] The optical film according to [1] or [2], wherein the content of the acid trapping agent is 0.1 to 5% by mass with respect to the composition.
[4] The optical film according to any one of [1] to [3], wherein the composition further contains a cellulose ester.
[5] The optical film according to [4], wherein the cellulose ester is cellulose acetate propionate.
[6] The content ratio of the (meth) acrylic resin and the cellulose ester is (meth) acrylic resin / cellulose ester = 90/10 to 50/50 by mass ratio, according to [4] or [5] Optical film.
[7] The optical film according to any one of [1] to [6], wherein the (meth) acrylic resin has a lactone ring structure.
[8] The optical film according to any one of [1] to [7], wherein the composition further contains an acrylonitrile / styrene copolymer.
[9] [1]~[8]のいずれかに記載の光学フィルムを含む、偏光板保護フィルム。
[10] 下記式で定義され、波長590nmにおいて測定される厚み方向のレターデーションRthが-5nm以上5nm以下である、[9]に記載の偏光板保護フィルム。
Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向の屈折率、ny:フィルム面内において、遅相軸に対して直交する方向の屈折率、nz:厚み方向におけるフィルムの屈折率、d:フィルムの厚み(nm))
[11] 偏光子と、前記偏光子の少なくとも一方の面に配置された[9]または[10]に記載の偏光板保護フィルムとを含む、偏光板。
[12] 液晶セルと、前記液晶セルの少なくとも一方の面に配置された[11]に記載の偏光板とを含む、液晶表示装置。
[13] [1]~[8]のいずれかに記載の光学フィルムの製造方法であって、前記(メタ)アクリル樹脂と、前記酸トラップ剤とを含有する樹脂組成物を、溶融混練した後、フィルム状に押し出すステップを含む、光学フィルムの製造方法。
[14] 前記樹脂組成物が、セルロースエステルをさらに含有する、[13]に記載の光学フィルムの製造方法。
[15] 前記樹脂組成物の溶融温度は、240~270℃である、[13]または[14]に記載の光学フィルムの製造方法。 [9] A polarizing plate protective film comprising the optical film according to any one of [1] to [8].
[10] The polarizing plate protective film according to [9], which is defined by the following formula and has a thickness direction retardation Rth measured at a wavelength of 590 nm of −5 nm to 5 nm.
Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))
[11] A polarizing plate comprising a polarizer and the polarizing plate protective film according to [9] or [10] disposed on at least one surface of the polarizer.
[12] A liquid crystal display device comprising a liquid crystal cell and the polarizing plate according to [11] disposed on at least one surface of the liquid crystal cell.
[13] The method for producing an optical film according to any one of [1] to [8], wherein the resin composition containing the (meth) acrylic resin and the acid trapping agent is melt-kneaded. The manufacturing method of an optical film including the step extruded in a film form.
[14] The method for producing an optical film according to [13], wherein the resin composition further contains a cellulose ester.
[15] The method for producing an optical film according to [13] or [14], wherein the melting temperature of the resin composition is 240 to 270 ° C.
[10] 下記式で定義され、波長590nmにおいて測定される厚み方向のレターデーションRthが-5nm以上5nm以下である、[9]に記載の偏光板保護フィルム。
Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向の屈折率、ny:フィルム面内において、遅相軸に対して直交する方向の屈折率、nz:厚み方向におけるフィルムの屈折率、d:フィルムの厚み(nm))
[11] 偏光子と、前記偏光子の少なくとも一方の面に配置された[9]または[10]に記載の偏光板保護フィルムとを含む、偏光板。
[12] 液晶セルと、前記液晶セルの少なくとも一方の面に配置された[11]に記載の偏光板とを含む、液晶表示装置。
[13] [1]~[8]のいずれかに記載の光学フィルムの製造方法であって、前記(メタ)アクリル樹脂と、前記酸トラップ剤とを含有する樹脂組成物を、溶融混練した後、フィルム状に押し出すステップを含む、光学フィルムの製造方法。
[14] 前記樹脂組成物が、セルロースエステルをさらに含有する、[13]に記載の光学フィルムの製造方法。
[15] 前記樹脂組成物の溶融温度は、240~270℃である、[13]または[14]に記載の光学フィルムの製造方法。 [9] A polarizing plate protective film comprising the optical film according to any one of [1] to [8].
[10] The polarizing plate protective film according to [9], which is defined by the following formula and has a thickness direction retardation Rth measured at a wavelength of 590 nm of −5 nm to 5 nm.
Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))
[11] A polarizing plate comprising a polarizer and the polarizing plate protective film according to [9] or [10] disposed on at least one surface of the polarizer.
[12] A liquid crystal display device comprising a liquid crystal cell and the polarizing plate according to [11] disposed on at least one surface of the liquid crystal cell.
[13] The method for producing an optical film according to any one of [1] to [8], wherein the resin composition containing the (meth) acrylic resin and the acid trapping agent is melt-kneaded. The manufacturing method of an optical film including the step extruded in a film form.
[14] The method for producing an optical film according to [13], wherein the resin composition further contains a cellulose ester.
[15] The method for producing an optical film according to [13] or [14], wherein the melting temperature of the resin composition is 240 to 270 ° C.
本発明によれば、(メタ)アクリル樹脂を主成分として含み、着色がなく、膜厚が薄く、かつリワーク性に優れた光学フィルムを提供できる。
According to the present invention, it is possible to provide an optical film that contains (meth) acrylic resin as a main component, is not colored, has a thin film thickness, and has excellent reworkability.
1.光学フィルム
本発明の光学フィルムは、(メタ)アクリル樹脂と、酸トラップ剤とを含有する組成物を含む。当該組成物は、セルロースエステルをさらに含有することが好ましい。 1. Optical film The optical film of this invention contains the composition containing a (meth) acrylic resin and an acid trap agent. The composition preferably further contains a cellulose ester.
本発明の光学フィルムは、(メタ)アクリル樹脂と、酸トラップ剤とを含有する組成物を含む。当該組成物は、セルロースエステルをさらに含有することが好ましい。 1. Optical film The optical film of this invention contains the composition containing a (meth) acrylic resin and an acid trap agent. The composition preferably further contains a cellulose ester.
(メタ)アクリル樹脂
(メタ)アクリル樹脂は、メチルメタクリレートの単独重合体、またはメチルメタクリレートと他の共重合モノマーとの共重合体であることが好ましい。共重合体におけるメチルメタクリレート由来の構成単位の含有割合は50質量%以上であることが好ましく、70質量%以上であることがより好ましい。 (Meth) acrylic resin The (meth) acrylic resin is preferably a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another copolymerizable monomer. The content ratio of the structural unit derived from methyl methacrylate in the copolymer is preferably 50% by mass or more, and more preferably 70% by mass or more.
(メタ)アクリル樹脂は、メチルメタクリレートの単独重合体、またはメチルメタクリレートと他の共重合モノマーとの共重合体であることが好ましい。共重合体におけるメチルメタクリレート由来の構成単位の含有割合は50質量%以上であることが好ましく、70質量%以上であることがより好ましい。 (Meth) acrylic resin The (meth) acrylic resin is preferably a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another copolymerizable monomer. The content ratio of the structural unit derived from methyl methacrylate in the copolymer is preferably 50% by mass or more, and more preferably 70% by mass or more.
共重合体における共重合モノマーの例には、アルキル部分の炭素数が2~18のアルキルメタクリレート;アルキル部分の炭素数が1~18のアルキルアクリレート;後述のラクトン環構造を形成しうる、水酸基を有するアルキル部分の炭素数が1~18のアルキル(メタ)アクリレート;アクリル酸、メタクリル酸などのα,β-不飽和酸;マレイン酸、フマル酸、イタコン酸などの不飽和基含有二価カルボン酸;スチレン、α-メチルスチレンなどの芳香族ビニル化合物;アクリロニトリル、メタクリロニトリルなどのα,β-不飽和ニトリル;無水マレイン酸、マレイミド、N-置換マレイミド、グルタル酸無水物など、アクリロイルモルホリン(ACMO)などのアクリルアミド誘導体;N-ビニルピロリドン(VP)などが含まれる。これらは、一種類で用いてもよいし、二種以上を組み合わせて用いてもよい。
Examples of copolymer monomers in the copolymer include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl portion; alkyl acrylates having 1 to 18 carbon atoms in the alkyl portion; hydroxyl groups that can form a lactone ring structure described later. Alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl moiety; α, β-unsaturated acids such as acrylic acid and methacrylic acid; unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid and itaconic acid Aromatic vinyl compounds such as styrene and α-methylstyrene; α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, acryloylmorpholine (ACMO); ) And other acrylamide derivatives; N-vinylpyrrolidone (VP) and the like are included . These may be used alone or in combination of two or more.
これらの共重合モノマーのなかでも、共重合体の耐熱分解性や流動性を高めるためには、メチルアクリレート、エチルアクリレート、n-プロピルアクリレート、n-ブチルアクリレート、s-ブチルアクリレート、2-エチルヘキシルアクリレートなどのアルキルアクリレート;2-(ヒドロキシメチル)アクリル酸メチル、2-(ヒドロキシメチル)アクリル酸エチルなどの水酸基を有するアルキル(メタ)アクリレートが好ましい。セルロースエステルとの相溶性を高めるためには、アクリロイルモルホリンなどが好ましい。
Among these copolymer monomers, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate are used to improve the thermal decomposition resistance and fluidity of the copolymer. Alkyl (meth) acrylates having a hydroxyl group such as methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate are preferred. In order to enhance the compatibility with the cellulose ester, acryloylmorpholine and the like are preferable.
(メタ)アクリル樹脂は、得られる光学フィルムの耐熱性を高めたり、光弾性係数を調整したりする観点などから、ラクトン環構造を含有することが好ましい。(メタ)アクリル樹脂に含まれるラクトン環構造は、好ましくは下記一般式(1)で表される。
The (meth) acrylic resin preferably contains a lactone ring structure from the viewpoint of enhancing the heat resistance of the resulting optical film or adjusting the photoelastic coefficient. The lactone ring structure contained in the (meth) acrylic resin is preferably represented by the following general formula (1).
式(1)において、R1~R3は、それぞれ独立に水素原子または炭素数1~20の有機残基を示す。有機残基は、酸素原子を含んでいてもよい。有機残基の例には、直鎖もしくは分岐状のアルキル基、直鎖もしくは分岐状のアルキレン基、アリール基、-OAc基(Acはアセチル基)、-CN基などが含まれる。式(1)で示されるラクトン環構造は、後述するように、水酸基を有するアルキル(メタ)アクリレートに由来する構造である。
In the formula (1), R 1 to R 3 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom. Examples of organic residues include linear or branched alkyl groups, linear or branched alkylene groups, aryl groups, —OAc groups (Ac is an acetyl group), —CN groups, and the like. The lactone ring structure represented by the formula (1) is a structure derived from an alkyl (meth) acrylate having a hydroxyl group, as will be described later.
ラクトン環構造を含有する(メタ)アクリル樹脂は、アルキル部分の炭素数が1~18のアルキル(メタ)アクリレートに由来する構成単位をさらに含み、必要に応じて水酸基を含有するモノマー、不飽和カルボン酸、一般式(2)で表されるモノマーなどに由来する構成単位をさらに含んでいてもよい。一般式(2)におけるR4は、水素原子またはメチル基を示す。Xは、水素原子、炭素数1~20のアルキル基、アリール基、-OAc基(Ac:アセチル基)、-CN基、アシル基または-C-OR基(Rは水素原子または炭素数1~20の有機残基)を示す。
The (meth) acrylic resin containing a lactone ring structure further includes a structural unit derived from an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl portion, and if necessary, a monomer containing a hydroxyl group, an unsaturated carboxylic acid A structural unit derived from an acid, a monomer represented by the general formula (2), or the like may be further included. R 4 in the general formula (2) represents a hydrogen atom or a methyl group. X is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, —OAc group (Ac: acetyl group), —CN group, acyl group, or —C—OR group (R is a hydrogen atom or 1 to 20 organic residues).
ラクトン環構造を含有する(メタ)アクリル樹脂における、式(1)で表されるラクトン環構造の含有割合は、好ましくは5~90質量%であり、より好ましくは10~80質量%であり、さらに好ましくは15~70質量%である。ラクトン環構造の含有割合が90質量%超であると、成形加工性が低く、得られるフィルムの可とう性も低くなりやすい。ラクトン環構造の含有割合が5質量%未満であると、必要な位相差を有するフィルムが得られにくく、耐熱性、耐溶剤性、表面硬度が十分でないことがある。
The content ratio of the lactone ring structure represented by the formula (1) in the (meth) acrylic resin containing a lactone ring structure is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, More preferably, it is 15 to 70% by mass. When the content of the lactone ring structure is more than 90% by mass, the molding processability is low, and the flexibility of the obtained film tends to be low. When the content of the lactone ring structure is less than 5% by mass, it is difficult to obtain a film having a necessary retardation, and heat resistance, solvent resistance, and surface hardness may not be sufficient.
ラクトン環構造を含有する(メタ)アクリル樹脂における、アルキル(メタ)アクリレートに由来する構成単位の含有割合は、好ましくは10~95質量%であり、より好ましくは20~90質量%であり、さらに好ましくは30~85質量%である。
In the (meth) acrylic resin containing a lactone ring structure, the content of the structural unit derived from the alkyl (meth) acrylate is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, Preferably, the content is 30 to 85% by mass.
ラクトン環構造を含有する(メタ)アクリル樹脂における、水酸基含有モノマー、不飽和カルボン酸または一般式(2)で表されるモノマーに由来する構成単位の含有割合は、それぞれ独立に好ましくは0~30質量%であり、より好ましくは0~20質量%であり、さらに好ましくは0~10質量%である。
In the (meth) acrylic resin containing a lactone ring structure, the content ratio of the structural unit derived from the hydroxyl group-containing monomer, the unsaturated carboxylic acid, or the monomer represented by the general formula (2) is preferably independently from 0 to 30. % By mass, more preferably 0 to 20% by mass, and still more preferably 0 to 10% by mass.
ラクトン環構造を含有する(メタ)アクリル樹脂は、少なくとも、水酸基を有するアルキル(メタ)アクリレートと、それ以外のアルキル(メタ)アクリレートとを含むモノマー成分を重合反応させて、分子鎖中に水酸基とエステル基とを有する重合体を得るステップ;得られた重合体を加熱処理してラクトン環構造を導入するステップ、を経て製造されうる。
The (meth) acrylic resin containing a lactone ring structure is obtained by polymerizing a monomer component containing at least an alkyl (meth) acrylate having a hydroxyl group and another alkyl (meth) acrylate to form a hydroxyl group in the molecular chain. It can be produced through a step of obtaining a polymer having an ester group; a step of introducing a lactone ring structure by heat-treating the obtained polymer.
(メタ)アクリル樹脂の重量平均分子量Mwは、好ましくは8.0×104~5.0×105の範囲内であり、より好ましくは9.0×104~4.5×105の範囲内であり、さらに好ましくは1.0×105~4.0×105の範囲内である。(メタ)アクリル樹脂の重量平均分子量Mwが8.0×104未満であると、得られるフィルムの脆性が高すぎることがあり、5.0×105超であると、溶融物の粘度が高すぎたり、得られるフィルムのヘイズが高かったりする。
The weight average molecular weight Mw of the (meth) acrylic resin is preferably in the range of 8.0 × 10 4 to 5.0 × 10 5 , more preferably 9.0 × 10 4 to 4.5 × 10 5 . Within the range, more preferably within the range of 1.0 × 10 5 to 4.0 × 10 5 . If the weight average molecular weight Mw of the (meth) acrylic resin is less than 8.0 × 10 4 , the resulting film may be too brittle, and if it exceeds 5.0 × 10 5 , the viscosity of the melt It is too high or the resulting film has a high haze.
(メタ)アクリル樹脂の重量平均分子量Mwは、ゲルパーミエーションクロマトグラフィーにより測定することができる。測定条件は以下の通りである。
溶媒: メチレンクロライド
カラム: Shodex K806、K805、K803G(昭和電工(株)製を3本接続して使用する)
カラム温度:25℃
試料濃度: 0.1質量%
検出器: RI Model 504(GLサイエンス社製)
ポンプ: L6000(日立製作所(株)製)
流量: 1.0ml/min
校正曲線: 標準ポリスチレンSTK standard ポリスチレン(東ソー(株)製)Mw=2800000~500迄の13サンプルによる校正曲線を使用する。13サンプルは、ほぼ等間隔に用いることが好ましい。 The weight average molecular weight Mw of the (meth) acrylic resin can be measured by gel permeation chromatography. The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2800000-500 13 calibration samples are used. The 13 samples are preferably used at approximately equal intervals.
溶媒: メチレンクロライド
カラム: Shodex K806、K805、K803G(昭和電工(株)製を3本接続して使用する)
カラム温度:25℃
試料濃度: 0.1質量%
検出器: RI Model 504(GLサイエンス社製)
ポンプ: L6000(日立製作所(株)製)
流量: 1.0ml/min
校正曲線: 標準ポリスチレンSTK standard ポリスチレン(東ソー(株)製)Mw=2800000~500迄の13サンプルによる校正曲線を使用する。13サンプルは、ほぼ等間隔に用いることが好ましい。 The weight average molecular weight Mw of the (meth) acrylic resin can be measured by gel permeation chromatography. The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2800000-500 13 calibration samples are used. The 13 samples are preferably used at approximately equal intervals.
(メタ)アクリル樹脂は、例えば懸濁重合、乳化重合、溶液重合または塊状重合などの公知の方法で製造されうる。重合開始剤は、通常のパーオキサイド系化合物、アゾ系化合物、レドックス系化合物を用いることができる。重合温度は、懸濁重合または乳化重合では30~100℃程度とし;溶液重合または塊状重合では、80~160℃程度としうる。得られる重合体の還元粘度を調整するために、アルキルメルカプタン等を連鎖移動剤として用いてもよい。
(Meth) acrylic resin can be produced by a known method such as suspension polymerization, emulsion polymerization, solution polymerization or bulk polymerization. As the polymerization initiator, a normal peroxide compound, azo compound, or redox compound can be used. The polymerization temperature can be about 30 to 100 ° C. for suspension polymerization or emulsion polymerization; it can be about 80 to 160 ° C. for solution polymerization or bulk polymerization. In order to adjust the reduced viscosity of the resulting polymer, alkyl mercaptan or the like may be used as a chain transfer agent.
(メタ)アクリル樹脂の市販品の例には、デルペット60N、80N(旭化成ケミカルズ(株)製)、ダイヤナールBR52、BR80、BR83、BR85、BR88(三菱レイヨン(株)製)、KT75(電気化学工業(株)製)などが含まれる。
Examples of commercially available (meth) acrylic resins include Delpet 60N, 80N (Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electricity). Chemical Industry Co., Ltd.).
(メタ)アクリル樹脂は、一種類であっても、二種類以上の混合物であってもよい。
(Meth) acrylic resin may be one kind or a mixture of two or more kinds.
セルロースエステル
セルロースエステルは、セルロースを、脂肪族カルボン酸または芳香族カルボン酸とエステル化反応させて得られる化合物である。セルロースエステルに含まれるアシル基は、脂肪族アシル基または芳香族アシル基であり、好ましくは脂肪族アシル基である。脂肪族アシル基は、直鎖であっても分岐していてもよく、さらに置換基を有してもよい。アシル基で置換されていない部分は、通常、水酸基として存在している。 Cellulose ester Cellulose ester is a compound obtained by esterifying cellulose with aliphatic carboxylic acid or aromatic carboxylic acid. The acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group. The aliphatic acyl group may be linear or branched and may further have a substituent. The portion that is not substituted with an acyl group usually exists as a hydroxyl group.
セルロースエステルは、セルロースを、脂肪族カルボン酸または芳香族カルボン酸とエステル化反応させて得られる化合物である。セルロースエステルに含まれるアシル基は、脂肪族アシル基または芳香族アシル基であり、好ましくは脂肪族アシル基である。脂肪族アシル基は、直鎖であっても分岐していてもよく、さらに置換基を有してもよい。アシル基で置換されていない部分は、通常、水酸基として存在している。 Cellulose ester Cellulose ester is a compound obtained by esterifying cellulose with aliphatic carboxylic acid or aromatic carboxylic acid. The acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group. The aliphatic acyl group may be linear or branched and may further have a substituent. The portion that is not substituted with an acyl group usually exists as a hydroxyl group.
セルロースエステルは、(メタ)アクリル樹脂との相溶性を高めたり、得られるフィルムの脆性を付与したりする観点から、アシル基の総置換度(Dall)が2.0~3.0であることが好ましく、2.5~3.0であることがより好ましい。セルロースエステルのアシル基の総置換度が2.0未満であると、(メタ)アクリル樹脂とセルロースエステルとが十分に相溶せず、得られるフィルムのヘイズが高いことがある。
The cellulose ester has a total acyl group substitution degree (Dall) of 2.0 to 3.0 from the viewpoint of enhancing compatibility with the (meth) acrylic resin or imparting brittleness of the resulting film. Is more preferable, and 2.5 to 3.0 is more preferable. When the total substitution degree of the acyl group of the cellulose ester is less than 2.0, the (meth) acrylic resin and the cellulose ester may not be sufficiently compatible, and the resulting film may have high haze.
このうち、炭素数3~7のアシル基の置換度は、1.2~3.0であることが好ましく、2.0~3.0であることがより好ましい。炭素数3~7のアシル基の置換度が1.2未満であると、(メタ)アクリル樹脂とセルロースエステルとが十分に相溶しにくく、得られるフィルムのヘイズが高かったり、脆性が高かったりするからである。
Of these, the substitution degree of the acyl group having 3 to 7 carbon atoms is preferably 1.2 to 3.0, more preferably 2.0 to 3.0. When the substitution degree of the acyl group having 3 to 7 carbon atoms is less than 1.2, the (meth) acrylic resin and the cellulose ester are not sufficiently compatible with each other, and the resulting film has high haze or high brittleness. Because it does.
アシル基の置換度は、ASTM-D817-96に規定の方法で測定することができる。
The degree of acyl group substitution can be measured by the method prescribed in ASTM-D817-96.
セルロースエステルの例には、セルロースアセテート、セルロースアセテートプロピオネート、セルロースアセテートブチレート、セルロースアセテートベンゾエート、セルロースプロピオネート、セルロースブチレートなどが含まれ、好ましくはセルロースアセテートプロピオネート、セルロースプロピオネートである。
Examples of cellulose esters include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, cellulose butyrate, preferably cellulose acetate propionate, cellulose propionate. It is.
セルロースエステル樹脂の重量平均分子量Mwは、(メタ)アクリル樹脂との相溶性を高める観点から、7.5×104以上であることが好ましく、7.5×104~2.4×105の範囲であることがより好ましく、1.0×105~2.4×105の範囲であることがさらに好ましく、1.6×105~2.4×105の範囲であることが特に好ましい。重量平均分子量Mwが7.5×104未満であると、得られるフィルムの可とう性が低く、耐熱性が十分でないことがある。一方、重量平均分子量Mwが2.4×105超であると、溶融物の粘度が高く、溶融押し出ししにくいだけでなく、(メタ)アクリル樹脂との相溶性が低く、得られる光学フィルムのヘイズが上昇しやすい。
The weight average molecular weight Mw of the cellulose ester resin is preferably 7.5 × 10 4 or more from the viewpoint of enhancing the compatibility with the (meth) acrylic resin, and 7.5 × 10 4 to 2.4 × 10 5. Is more preferably in the range of 1.0 × 10 5 to 2.4 × 10 5 , further preferably in the range of 1.6 × 10 5 to 2.4 × 10 5. Particularly preferred. When the weight average molecular weight Mw is less than 7.5 × 10 4 , the resulting film has low flexibility and heat resistance may be insufficient. On the other hand, when the weight average molecular weight Mw is more than 2.4 × 10 5 , the melt has a high viscosity and is difficult to melt and extrude, and has a low compatibility with the (meth) acrylic resin. Haze tends to rise.
セルロースエステルのTgは、100℃以上であることが好ましく、120℃以上であることがより好ましい。セルロースエステルのTgの上限は、約190℃としうる。セルロースエステルのTgは、JIS K 7121に準拠した方法で測定されうる。
The Tg of the cellulose ester is preferably 100 ° C. or higher, and more preferably 120 ° C. or higher. The upper limit of the Tg of the cellulose ester can be about 190 ° C. The Tg of cellulose ester can be measured by a method based on JIS K7121.
セルロースエステルは、公知の方法で合成することができる。具体的には、セルロースと、少なくとも酢酸またはその無水物を含む炭素原子数3以上の有機酸またはその無水物とを、触媒の存在下でエステル化反応させてセルロースのトリエステル体を合成する。次いで、セルロースのトリエステルを加水分解して、所望のアシル置換度を有するセルロースエステル樹脂を合成する。得られたセルロースエステル樹脂を、ろ過、沈殿、水洗、脱水および乾燥させた後、セルロースエステル樹脂を得ることができる(特開平10-45804号に記載の方法を参照)。
Cellulose ester can be synthesized by a known method. Specifically, cellulose is esterified with an organic acid having at least 3 carbon atoms containing acetic acid or an anhydride thereof or an anhydride thereof in the presence of a catalyst to synthesize a triester of cellulose. The cellulose triester is then hydrolyzed to synthesize a cellulose ester resin having the desired degree of acyl substitution. After the obtained cellulose ester resin is filtered, precipitated, washed with water, dehydrated and dried, a cellulose ester resin can be obtained (see the method described in JP-A-10-45804).
原料となるセルロースは、例えば綿花リンター、木材パルプ(針葉樹由来、広葉樹由来)およびケナフなどを用いることができる。原料となるセルロースは、一種類だけであってもよいし、二種類以上の混合物であってもよい。
As the cellulose used as a raw material, for example, cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like can be used. The cellulose used as a raw material may be only one type or a mixture of two or more types.
本発明の光学フィルムにおける(メタ)アクリル樹脂とセルロースエステルの合計含有量は、光学フィルムに対して好ましくは55質量%以上であり、より好ましくは60質量%以上であり、さらに好ましくは70質量%以上である。
The total content of the (meth) acrylic resin and the cellulose ester in the optical film of the present invention is preferably 55% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass with respect to the optical film. That's it.
(メタ)アクリル樹脂とセルロースエステルの含有比率(質量比)は、(メタ)アクリル樹脂:セルロースエステル=95:5~30:70であることが好ましく、90:10~50:50であることがより好ましく、90:10~60:40であることがさらに好ましい。
The content ratio (mass ratio) between the (meth) acrylic resin and the cellulose ester is preferably (meth) acrylic resin: cellulose ester = 95: 5 to 30:70, and preferably 90:10 to 50:50. More preferably, it is 90:10 to 60:40.
(メタ)アクリル樹脂の含有割合が、(メタ)アクリル樹脂とセルロースエステルの合計に対して95質量%超であると、セルロースエステルによる効果が十分に得られず、30質量%未満であると、得られるフィルムの耐熱湿性が十分であることがある。
When the content ratio of the (meth) acrylic resin is more than 95% by mass with respect to the total of the (meth) acrylic resin and the cellulose ester, the effect due to the cellulose ester is not sufficiently obtained, and is less than 30% by mass, The resulting film may have sufficient heat and humidity resistance.
本発明の光学フィルムは、本発明の効果を損なわない範囲で、(メタ)アクリル樹脂、セルロースエステル以外のその他の樹脂をさらに含有してもよい。
The optical film of the present invention may further contain other resins other than the (meth) acrylic resin and cellulose ester as long as the effects of the present invention are not impaired.
その他の樹脂の好ましい例には、スチレン系樹脂などが含まれる。スチレン系樹脂は、スチレンモノマーの単独重合体(ポリスチレン)、スチレンモノマーと他の共重合可能なモノマーとの共重合体、またはこれらの重合体の変性物などであり、好ましくはスチレンモノマーと他の共重合可能なモノマーとの共重合体である。共重合体における、スチレンモノマー由来の構成単位の含有割合は0~20質量%の範囲であることが好ましい。
Preferred examples of other resins include styrene resins. The styrenic resin is a homopolymer of styrene monomer (polystyrene), a copolymer of a styrene monomer and another copolymerizable monomer, or a modified product of these polymers, preferably styrene monomer and other It is a copolymer with a copolymerizable monomer. The content of the structural unit derived from the styrene monomer in the copolymer is preferably in the range of 0 to 20% by mass.
スチレンモノマーと他の共重合可能なモノマーの例には、無水マレイン酸、アクリロニトリル、マレイミドなどが含まれ、好ましくはアクリロニトリルである。スチレン・アクリロニトリル共重合体は、それを含むフィルムに柔軟性を付与しうる。
Examples of the copolymerizable monomer with the styrene monomer include maleic anhydride, acrylonitrile, maleimide and the like, preferably acrylonitrile. The styrene / acrylonitrile copolymer can impart flexibility to a film containing the copolymer.
酸トラップ剤
本発明の光学フィルムを構成する組成物は、酸トラップ剤をさらに含有する。酸トラップ剤の好ましい例には、アルキルリン酸金属塩、エポキシ基を含有する化合物などが含まれる。 Acid Trap Agent The composition constituting the optical film of the present invention further contains an acid trap agent. Preferable examples of the acid trapping agent include alkyl phosphate metal salts and compounds containing an epoxy group.
本発明の光学フィルムを構成する組成物は、酸トラップ剤をさらに含有する。酸トラップ剤の好ましい例には、アルキルリン酸金属塩、エポキシ基を含有する化合物などが含まれる。 Acid Trap Agent The composition constituting the optical film of the present invention further contains an acid trap agent. Preferable examples of the acid trapping agent include alkyl phosphate metal salts and compounds containing an epoxy group.
アルキルリン酸金属塩は、炭素数2~20のアルキルリン酸の金属塩である。アルキルリン酸金属塩を構成する金属原子は、第2族または第12族の金属原子であり、好ましくは亜鉛、カルシウム、マグネシウムなどが含まれる。
The alkyl phosphate metal salt is a metal salt of an alkyl phosphate having 2 to 20 carbon atoms. The metal atom constituting the alkyl phosphate metal salt is a Group 2 or Group 12 metal atom, and preferably includes zinc, calcium, magnesium and the like.
アルキルリン酸金属塩を構成する炭素数2~20のアルキルリン酸の例には、エチルリン酸、ブチルリン酸、ラウリルリン酸、ステアリルリン酸などが含まれ、好ましくはステアリルリン酸である。
Examples of the alkyl phosphoric acid having 2 to 20 carbon atoms constituting the alkyl phosphoric acid metal salt include ethyl phosphoric acid, butyl phosphoric acid, lauryl phosphoric acid, stearyl phosphoric acid and the like, preferably stearyl phosphoric acid.
アルキルリン酸金属塩の市販品の例には、堺化学社製LBT-1830などが含まれる。
Examples of commercially available alkyl phosphate metal salts include LBT-1830 manufactured by Sakai Chemical.
エポキシ基を含有する化合物の例には、エポキシ化大豆油、エポキシ化亜麻仁油、エポキシ化脂肪酸アルキルエステル、エポキシ化1,2ポリブタジエンなどのエポキシ化植物油が含まれる。エポキシ化脂肪酸アルキルエステルの例には、エポキシ化脂肪酸オクチルエステル(旭電化社製アデカサイザーD-32)、エポキシ化脂肪酸イソブチルエステル(旭電化社製アデカサイザーD-55)などが含まれる。エポキシ化1,2ポリブタジエンの例には、アデカサイザーBF-1000(平均分子量10000)などが含まれる。エポキシ基を含有する化合物の例には、米国特許第4,137,201号に記載のエポキシ基を含有する化合物なども含まれる。
Examples of the compound containing an epoxy group include epoxidized vegetable oils such as epoxidized soybean oil, epoxidized linseed oil, epoxidized fatty acid alkyl ester, and epoxidized 1,2 polybutadiene. Examples of the epoxidized fatty acid alkyl ester include epoxidized fatty acid octyl ester (Adekasizer D-32 manufactured by Asahi Denka Co., Ltd.), epoxidized fatty acid isobutyl ester (Adekasizer D-55 manufactured by Asahi Denka Co., Ltd.), and the like. Examples of the epoxidized 1,2 polybutadiene include Adekasizer BF-1000 (average molecular weight 10,000). Examples of the compound containing an epoxy group include compounds containing an epoxy group described in US Pat. No. 4,137,201.
本発明の光学フィルムは、後述するように、(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を溶融混練した後、押し出すステップを経て得ることができる。リワーク性の高い光学フィルム;即ち、柔軟性の高い光学フィルムを得るためには、樹脂組成物を溶融混練する際の溶融温度を高くして、樹脂の流動性を高めることが有効である。しかしながら、溶融温度を高くすると、原材料である(メタ)アクリル樹脂に残留するモノマーが熱分解して酸を発生したり、セルロースエステルのエステル部が加水分解して酸を発生したりし、これらの酸が樹脂を熱劣化させやすい。一方、酸トラップ剤は、これらの酸をトラップしうることから、溶融温度を高くしても、樹脂の熱劣化を抑制することができる。
As will be described later, the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent. In order to obtain an optical film having high reworkability; that is, to obtain an optical film having high flexibility, it is effective to increase the resin fluidity by increasing the melting temperature when melt-kneading the resin composition. However, when the melting temperature is increased, the monomer remaining in the raw material (meth) acrylic resin is thermally decomposed to generate an acid, or the ester portion of the cellulose ester is hydrolyzed to generate an acid. Acid tends to cause thermal degradation of the resin. On the other hand, since the acid trapping agent can trap these acids, thermal degradation of the resin can be suppressed even if the melting temperature is increased.
酸トラップ剤の含有量は、後述する溶融混練時の樹脂の熱分解を抑制するためには、前記組成物に対して0.1質量%以上であることが好ましく、0.5質量%以上であることがより好ましく、1.0質量%以上であることがさらに好ましい。一方で、酸トラップ剤の含有量が多すぎると、得られる光学フィルムがブリードアウトを生じたり、得られる光学フィルムと偏光子とを貼り合わせた際に偏光子を退色させたりするのを抑制するためなどから、酸トラップ剤の含有量は、5.0質量%以下であること好ましい。
The content of the acid trapping agent is preferably 0.1% by mass or more, preferably 0.5% by mass or more with respect to the composition in order to suppress thermal decomposition of the resin during melt kneading described later. More preferably, it is more preferably 1.0% by mass or more. On the other hand, when the content of the acid trapping agent is too large, the resulting optical film is prevented from bleeding out or from fading the polarizer when the obtained optical film and the polarizer are bonded together. Therefore, the content of the acid trapping agent is preferably 5.0% by mass or less.
本発明の光学フィルムは、本発明の効果を損なわない範囲で、滑剤、酸化防止剤、熱劣化防止剤、紫外線吸収剤、着色剤、微粒子(マット剤)などの添加剤をさらに含有していてもよい。
The optical film of the present invention further contains additives such as a lubricant, an antioxidant, a thermal degradation inhibitor, an ultraviolet absorber, a colorant, and fine particles (matting agent) as long as the effects of the present invention are not impaired. Also good.
滑剤
本発明の光学フィルムを構成する組成物は、透明性や面品質を高めるためなどから、滑剤をさらに含有してもよい。滑剤は、後述する樹脂組成物の溶融粘度を低下させ、混練性を高めうるだけでなく、溶融押し出しする際に、押し出し機やダイの内部における溶融樹脂の滞留を抑制しうる。 Lubricant The composition constituting the optical film of the present invention may further contain a lubricant in order to improve transparency and surface quality. The lubricant can not only lower the melt viscosity of the resin composition described later and improve the kneadability, but also can suppress the retention of the molten resin in the extruder or the die during the melt extrusion.
本発明の光学フィルムを構成する組成物は、透明性や面品質を高めるためなどから、滑剤をさらに含有してもよい。滑剤は、後述する樹脂組成物の溶融粘度を低下させ、混練性を高めうるだけでなく、溶融押し出しする際に、押し出し機やダイの内部における溶融樹脂の滞留を抑制しうる。 Lubricant The composition constituting the optical film of the present invention may further contain a lubricant in order to improve transparency and surface quality. The lubricant can not only lower the melt viscosity of the resin composition described later and improve the kneadability, but also can suppress the retention of the molten resin in the extruder or the die during the melt extrusion.
滑剤は、エステルワックス類または多価アルコール脂肪酸エステル類でありうる。エステルワックス類は、多価アルコールの全てのヒドロキシル基を脂肪酸でエステル化させて得られる化合物である。多価アルコール脂肪酸エステル類は、多価アルコールの一部のヒドロキシル基を、脂肪酸でエステル化させて得られる化合物である。
Lubricants can be ester waxes or polyhydric alcohol fatty acid esters. Ester waxes are compounds obtained by esterifying all hydroxyl groups of a polyhydric alcohol with a fatty acid. Polyhydric alcohol fatty acid esters are compounds obtained by esterifying a part of hydroxyl groups of a polyhydric alcohol with a fatty acid.
エステルワックス類または多価アルコール脂肪酸エステル類を構成する脂肪酸は、後述するように、加熱下での揮発による工程の汚染を抑制し、かつセルロースエステルとの相溶性を高める観点などから、炭素数12~22の脂肪酸であることが好ましい。脂肪酸は、飽和脂肪酸であっても不飽和脂肪酸であってもよいが、保存時の防臭、変色防止等の観点から、飽和脂肪酸が好ましい。
As will be described later, the fatty acid constituting the ester wax or the polyhydric alcohol fatty acid ester has 12 carbon atoms from the viewpoint of suppressing contamination of the process due to volatilization under heating and increasing the compatibility with the cellulose ester. A fatty acid of ˜22 is preferred. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but a saturated fatty acid is preferable from the viewpoint of deodorization and prevention of discoloration during storage.
そのような飽和脂肪酸の例には、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、ベヘニン酸、12-ヒドロキシステアリン酸、オレイン酸、リノール酸、エルシン酸、12-ヒドロキシオレイン酸などが含まれ、好ましくはステアリン酸である。脂肪酸は、一種類であってもよいし、二種類以上の混合物であってもよい。
Examples of such saturated fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, erucic acid, 12-hydroxyoleic acid, etc. Stearic acid is preferred. One type of fatty acid may be used, or a mixture of two or more types may be used.
エステルワックス類または多価アルコール脂肪酸エステル類を構成する多価アルコールの例には、アドニトール、アラビトール、エチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、1,2-プロパンジオール、1,3-プロパンジオール、ジプロピレングリコール、トリプロピレングリコール、1,2-ブタンジオール、1,3-ブタンジオール、1,4-ブタンジオール、ジブチレングリコール、1,2,4-ブタントリオール、1,5-ペンタンジオール、1,6-ヘキサンジオール、1,2,3-ヘキサントリオール、1,2,6-ヘキサントリオール、グリセリン、ジグリセリン、ガラクチトール、イノシトール、マンニトール、3-メチルペンタン-1,3,5-トリオール、ピナコール、ソルビトール、トリメチロールプロパン、トリメチロールエタン、ペンタエリスリトール、ジペンタエリスリトール、キシリトールなどが含まれる。これらのアルコールは、一種類であってもよいし、二種類以上の混合物であってもよい。
Examples of polyhydric alcohols constituting ester waxes or polyhydric alcohol fatty acid esters include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propane Diol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol 1,6-hexanediol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glycerin, diglycerin, galactitol, inositol, mannitol, 3-methylpentane-1,3,5-triol , Nakoru, sorbitol, trimethylol propane, trimethylol ethane, pentaerythritol, dipentaerythritol, and the like xylitol. These alcohols may be one kind or a mixture of two or more kinds.
エステルワックス類の好ましい例には、ペンタエリスリトールテトラ脂肪酸エステル、ジペンタエリスリトールヘキサ脂肪酸エステル、グリセリントリ脂肪酸エステルなどが含まれる。
Preferable examples of the ester wax include pentaerythritol tetrafatty acid ester, dipentaerythritol hexafatty acid ester, glycerin trifatty acid ester and the like.
多価アルコール脂肪酸エステル類の好ましい例には、グリセリンまたはジグリセリンの脂肪酸モノエステルまたはジエステル;ソルビトールの脂肪酸モノエステル、ジエステルまたはトリエステル;ソルビタンの脂肪酸モノエステル、ジエステルまたはトリエステルが含まれ、より好ましくはグリセリンまたはジグリセリンの脂肪酸物モノエステルまたはジエステル、ソルビタンの脂肪酸モノエステル、ジエステルまたはトリエステルであり、さらに好ましくはグリセリン脂肪酸モノエステルである。
Preferred examples of the polyhydric alcohol fatty acid esters include glycerin or diglycerin fatty acid monoester or diester; sorbitol fatty acid monoester, diester or triester; sorbitan fatty acid monoester, diester or triester, more preferably Is fatty acid monoester or diester of glycerin or diglycerin, fatty acid monoester, diester or triester of sorbitan, more preferably glycerin fatty acid monoester.
エステルワックス類は、後述する押し出し機の内壁面(金属面)と溶融樹脂との摩擦を低減させ、せん断発熱を低減しうる。しかしながら、エステルワックス類は、(メタ)アクリル樹脂やセルロースエステルなどとの相溶性が低いため、溶融粘度を下げる効果が小さく、得られるフィルムはブリードアウトを生じ易い。
The ester waxes can reduce friction between the inner wall surface (metal surface) of the extruder, which will be described later, and the molten resin, and can reduce shearing heat generation. However, since ester waxes have low compatibility with (meth) acrylic resins and cellulose esters, the effect of lowering the melt viscosity is small, and the resulting film tends to bleed out.
多価アルコール脂肪酸エステル類は、押し出し機の内壁面(金属面)と溶融樹脂との摩擦を低減させる効果はエステルワックス類よりも小さいが、溶融粘度を下げる効果が大きいため、せん断発熱を低減できる。また、多価アルコール脂肪酸エステル類は、(メタ)アクリル樹脂やセルロースエステルとの相溶性が高いため、得られるフィルムはブリードアウトを生じにくい。従って、多価アルコール脂肪酸エステル類を用いることが好ましい。
Polyhydric alcohol fatty acid esters have a smaller effect on reducing the friction between the inner wall (metal surface) of the extruder and the molten resin than ester waxes, but the effect of lowering the melt viscosity is great, so shear heat generation can be reduced. . In addition, since polyhydric alcohol fatty acid esters are highly compatible with (meth) acrylic resins and cellulose esters, the resulting film is less likely to bleed out. Therefore, it is preferable to use polyhydric alcohol fatty acid esters.
エステルワックス類または多価アルコール脂肪酸エステル類のエステル化反応は牛脂、豚脂、鶏脂、魚油、大豆油、コーン油、ナタネ油、パーム油、ヒマワリ油、サフラワー油、ヒマシ油あるいはそれらの水素添加油の一種または二種以上の混合物と、グリセリン、ジグリセリンまたはソルビトールとをエステル交換反応させた後、得られる反応物を精製して得ることができる。精製方法は、分子蒸留、溶剤分別、再結晶、カラムクロマトグラフィーまたは超臨界ガス抽出などの方法であってよく、製造の簡便さ、品質および価格などの面から、分子蒸留が一般的である。
The esterification reaction of ester waxes or polyhydric alcohol fatty acid esters is beef tallow, pork tallow, chicken tallow, fish oil, soybean oil, corn oil, rapeseed oil, palm oil, sunflower oil, safflower oil, castor oil or their hydrogen. One or a mixture of two or more of the additive oils and glycerin, diglycerin or sorbitol are subjected to a transesterification reaction, and then the resulting reaction product can be purified. The purification method may be a method such as molecular distillation, solvent fractionation, recrystallization, column chromatography, or supercritical gas extraction, and molecular distillation is generally used from the viewpoint of ease of production, quality, and price.
エステルワックス類または多価アルコール脂肪酸エステル類の含有量は、光学フィルムに対して0.05~2.0質量%であることが好ましく、0.1~1.0質量%であることがより好ましい。これらの含有量が0.05質量%未満であると、滑剤の効果が得られにくく、含有量が2.0質量%超であると、得られるフィルムの耐湿熱性が低下し、ヘイズが高くなりやすい。
The content of the ester wax or polyhydric alcohol fatty acid ester is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.0% by mass with respect to the optical film. . If these contents are less than 0.05% by mass, the effect of the lubricant is difficult to obtain, and if the content is more than 2.0% by mass, the heat-and-moisture resistance of the resulting film decreases and the haze increases. Cheap.
紫外線吸収剤
紫外線吸収剤は、波長400nm以下の紫外線を吸収する化合物であり、好ましくは波長370nmでの透過率が10%以下、より好ましくは5%以下、さらに好ましくは2%以下である化合物である。 Ultraviolet absorber The ultraviolet absorber is a compound that absorbs ultraviolet light having a wavelength of 400 nm or less, preferably a compound having a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% or less, and even more preferably 2% or less. is there.
紫外線吸収剤は、波長400nm以下の紫外線を吸収する化合物であり、好ましくは波長370nmでの透過率が10%以下、より好ましくは5%以下、さらに好ましくは2%以下である化合物である。 Ultraviolet absorber The ultraviolet absorber is a compound that absorbs ultraviolet light having a wavelength of 400 nm or less, preferably a compound having a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% or less, and even more preferably 2% or less. is there.
紫外線吸収剤の光線透過率は、紫外線吸収剤を溶媒(例えばジクロロメタン、トルエンなど)に溶解した溶液を、常法により、分光光度計により測定することができる。分光光度計は、例えば、島津製作所社製の分光光度計UVIDFC-610、日立製作所社製の330型自記分光光度計、U-3210型自記分光光度計、U-3410型自記分光光度計、U-4000型自記分光光度計等を用いることができる。
The light transmittance of the ultraviolet absorber can be measured with a spectrophotometer by a conventional method using a solution obtained by dissolving the ultraviolet absorber in a solvent (for example, dichloromethane, toluene, etc.). The spectrophotometer is, for example, a spectrophotometer UVIDFC-610 manufactured by Shimadzu Corporation, a 330-type self-recording spectrophotometer, a U-3210-type self-recording spectrophotometer, a U-3410-type self-recording spectrophotometer, manufactured by Hitachi, Ltd. -4000 self-recording spectrophotometer or the like can be used.
紫外線吸収剤は、オキシベンゾフェノン系化合物、ベンゾトリアゾール系化合物、サリチル酸エステル系化合物、ベンゾフェノン系化合物、シアノアクリレート系化合物、トリアジン系化合物、ニッケル錯塩系化合物、無機粉体および高分子紫外線吸収剤などであってよく、得られるフィルムの透明性を損なわないためには、好ましくはベンゾトリアゾール系紫外線吸収剤およびベンゾフェノン系紫外線吸収剤であり、さらに好ましくはベンゾトリアゾール系紫外線吸収剤がより好ましい。
Ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic powders, and polymer ultraviolet absorbers. In order not to impair the transparency of the obtained film, benzotriazole-based UV absorbers and benzophenone-based UV absorbers are preferable, and benzotriazole-based UV absorbers are more preferable.
紫外線吸収剤の具体例には、5-クロロ-2-(3,5-ジ-sec-ブチル-2-ヒドロキシルフェニル)-2H-ベンゾトリアゾール、(2-2H-ベンゾトリアゾール-2-イル)-6-(直鎖および側鎖ドデシル)-4-メチルフェノール、2-ヒドロキシ-4-ベンジルオキシベンゾフェノン、2,4-ベンジルオキシベンゾフェノンなどが含まれる。紫外線吸収剤の市販品の例には、チバ・ジャパン(株)製のTINUVIN109、TINUVIN171、TINUVIN326、TINUVIN327、TINUVIN328、TINUVIN900、TINUVIN928、ADEKA(株)製のLA-31などが含まれる。
Specific examples of UV absorbers include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- 6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone and the like are included. Examples of commercially available ultraviolet absorbers include TINUVIN109, TINUVIN171, TINUVIN326, TINUVIN327, TINUVIN328, TINUVIN900, TINUVIN928, and LA-31 manufactured by ADEKA Corporation, manufactured by Ciba Japan.
高分子紫外線吸収剤の例には、特開平6-148430号記載のポリマータイプの紫外線吸収剤が含まれる。紫外線吸収剤は、一種類であってもよいし、二種以上の混合物であってもよい。
Examples of polymer ultraviolet absorbers include polymer type ultraviolet absorbers described in JP-A-6-148430. The ultraviolet absorber may be one kind or a mixture of two or more kinds.
紫外線吸収剤の含有量は、紫外線吸収剤の種類にもよるが、光学フィルムに対して0.5~4質量%であることが好ましく、0.6~3.5質量%であることがより好ましい。
The content of the ultraviolet absorber is preferably 0.5 to 4% by mass, more preferably 0.6 to 3.5% by mass with respect to the optical film, although it depends on the type of the ultraviolet absorber. preferable.
酸化防止剤
溶融押出法でフィルムを製造する工程では、高温下で樹脂などのフィルム材料を溶融混練するため、樹脂などのフィルム材料が熱や酸素によって分解されやすい。そのような、樹脂などのフィルム材料の熱や酸素による分解を抑制するために、本発明の光学フィルムを構成する組成物は、安定化剤として酸化防止剤をさらに含むことが好ましい。 Antioxidant In the process of producing a film by the melt extrusion method, a film material such as a resin is melted and kneaded at a high temperature. In order to suppress such decomposition of the film material such as resin due to heat or oxygen, the composition constituting the optical film of the present invention preferably further contains an antioxidant as a stabilizer.
溶融押出法でフィルムを製造する工程では、高温下で樹脂などのフィルム材料を溶融混練するため、樹脂などのフィルム材料が熱や酸素によって分解されやすい。そのような、樹脂などのフィルム材料の熱や酸素による分解を抑制するために、本発明の光学フィルムを構成する組成物は、安定化剤として酸化防止剤をさらに含むことが好ましい。 Antioxidant In the process of producing a film by the melt extrusion method, a film material such as a resin is melted and kneaded at a high temperature. In order to suppress such decomposition of the film material such as resin due to heat or oxygen, the composition constituting the optical film of the present invention preferably further contains an antioxidant as a stabilizer.
酸化防止剤の例には、イオウ系化合物、フェノール系化合物、ヒンダードアミン系化合物、リン系化合物、不飽和二重結合を含有する化合物などが含まれる。
Examples of the antioxidant include sulfur compounds, phenol compounds, hindered amine compounds, phosphorus compounds, compounds containing unsaturated double bonds, and the like.
イオウ系化合物の例には、住友化学社製Sumilizer TPL-R、Sumilizer TP-Dなどが含まれる。
Examples of sulfur compounds include Sumitizer TPL-R, Sumilizer TP-D, etc. manufactured by Sumitomo Chemical Co., Ltd.
フェノール系化合物の例には、2,6-ジアルキルフェノールの構造を有する化合物(例えば2,6-ジ-t-ブチル-p-クレゾールなど)が含まれる。フェノール系化合物の市販品の例には、BASFジャパン株式会社製Irganox1076、Irganox1010などが含まれる。
Examples of phenolic compounds include compounds having a 2,6-dialkylphenol structure (for example, 2,6-di-t-butyl-p-cresol). Examples of commercially available phenolic compounds include Irganox 1076 and Irganox 1010 manufactured by BASF Japan Ltd.
リン系化合物の例には、トリス(2,4-ジ-t-ブチルフェニル)フォスファイト、ビス(2,6-ジ-t-ブチル-4-メチルフェニル)ペンタエリスリトール-ジホスファイト等が含まれる。リン系化合物の市販品の例には、住友化学株式会社製SumilizerGP、株式会社ADEKA製ADK STAB PEP-24G、ADK STAB PEP-36およびADK STAB 3010、BASFジャパン株式会社製IRGAFOS P-EPQ、堺化学工業株式会社製GSY-P101などが含まれる。
Examples of phosphorus compounds include tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite, and the like. Examples of commercially available phosphorus compounds include Sumitizer GP manufactured by Sumitomo Chemical Co., Ltd., ADK STAB PEP-24G manufactured by ADEKA Co., Ltd., ADK STAB PEP-36 and ADK STAB 3010, IRGAFOS P-EPQ manufactured by BASF Japan K.K. This includes GSY-P101 manufactured by Kogyo Corporation.
ヒンダードアミン系化合物の例には、BASFジャパン株式会社製Tinuvin144およびTinuvin770、株式会社ADEKA製ADK STAB LA-52などが含まれる。
Examples of hindered amine compounds include Tinuvin 144 and Tinuvin 770 manufactured by BASF Japan, and ADK STAB LA-52 manufactured by ADEKA.
不飽和二重結合を含有する化合物の例には、住友化学株式会社製Sumilizer GM、およびSumilizer GSなどが含まれる。
Examples of the compound containing an unsaturated double bond include Sumitizer GM and Sumilizer GS manufactured by Sumitomo Chemical Co., Ltd.
酸化防止剤は、一種類のみであっても二種類以上の混合物であってもよいが、好ましくは二種類以上の混合物であることが好ましい。例えば、リン系化合物、フェノール系化合物および不飽和二重結合を含有する化合物を併用することが好ましい。
The antioxidant may be only one kind or a mixture of two or more kinds, but is preferably a mixture of two or more kinds. For example, it is preferable to use a phosphorus compound, a phenol compound, and a compound containing an unsaturated double bond in combination.
酸化防止剤の含有量は、樹脂成分((メタ)アクリル樹脂とセルロースエステルの合計)に対して0.05~5質量%であることが好ましく、0.1~4質量%であることがより好ましい。
The content of the antioxidant is preferably 0.05 to 5% by mass, more preferably 0.1 to 4% by mass with respect to the resin component (total of (meth) acrylic resin and cellulose ester). preferable.
着色剤
本発明の光学フィルムを構成する組成物は、液晶表示画面の色調に青みを付与したり、イエローインデックス(黄色度)を調整したり、ヘイズを低減したりするためなどから、着色剤をさらに含有してもよい。着色剤の例には、アントラキノン染料、アゾ染料などの染料や、フタロシアニン顔料などの顔料が含まれる。 Colorant The composition constituting the optical film of the present invention contains a colorant for imparting bluishness to the color tone of the liquid crystal display screen, adjusting the yellow index (yellowness), and reducing haze. Furthermore, you may contain. Examples of the colorant include dyes such as anthraquinone dyes and azo dyes, and pigments such as phthalocyanine pigments.
本発明の光学フィルムを構成する組成物は、液晶表示画面の色調に青みを付与したり、イエローインデックス(黄色度)を調整したり、ヘイズを低減したりするためなどから、着色剤をさらに含有してもよい。着色剤の例には、アントラキノン染料、アゾ染料などの染料や、フタロシアニン顔料などの顔料が含まれる。 Colorant The composition constituting the optical film of the present invention contains a colorant for imparting bluishness to the color tone of the liquid crystal display screen, adjusting the yellow index (yellowness), and reducing haze. Furthermore, you may contain. Examples of the colorant include dyes such as anthraquinone dyes and azo dyes, and pigments such as phthalocyanine pigments.
微粒子(マット剤)
本発明の光学フィルムを構成する組成物は、得られる光学フィルムの表面の滑り性を高めるためなどから、微粒子(マット剤)をさらに含有してもよい。光学フィルムが多層である場合、最表面にある層が微粒子を含有することが好ましい。 Fine particles (matting agent)
The composition constituting the optical film of the present invention may further contain fine particles (matting agent) in order to enhance the slipperiness of the surface of the obtained optical film. When the optical film is a multilayer, the layer on the outermost surface preferably contains fine particles.
本発明の光学フィルムを構成する組成物は、得られる光学フィルムの表面の滑り性を高めるためなどから、微粒子(マット剤)をさらに含有してもよい。光学フィルムが多層である場合、最表面にある層が微粒子を含有することが好ましい。 Fine particles (matting agent)
The composition constituting the optical film of the present invention may further contain fine particles (matting agent) in order to enhance the slipperiness of the surface of the obtained optical film. When the optical film is a multilayer, the layer on the outermost surface preferably contains fine particles.
微粒子は、無機微粒子であっても有機微粒子であってもよい。無機微粒子の例には、二酸化珪素(シリカ)、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、炭酸カルシウム、炭酸カルシウム、タルク、クレイ、焼成カオリン、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウムおよびリン酸カルシウムなどが含まれる。なかでも、二酸化珪素や酸化ジルコニウムが好ましく、得られるフィルムのヘイズの増大を少なくするためには、より好ましくは二酸化珪素である。
The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.
二酸化珪素の微粒子の例には、アエロジルR972、R972V、R974、R812、200、200V、300、R202、OX50、TT600、NAX50(以上日本アエロジル(株)製)、シーホスターKE-P10、KE-P30、KE-P50、KE-P100(以上日本触媒(株)製)などが含まれる。
Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included.
酸化ジルコニウムの微粒子の例には、アエロジルR976およびR811(以上日本アエロジル(株)製)などが含まれる。
Examples of the zirconium oxide fine particles include Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.).
ポリマー微粒子を構成するポリマーの種類には、シリコーン樹脂、フッ素樹脂およびアクリル樹脂などが含まれ、好ましくはシリコーン樹脂であり、より好ましくは三次元の網状構造を有するシリコーン樹脂である。ポリマー微粒子の例には、トスパール103、同105、同108、同120、同145、同3120及び同240(以上東芝シリコーン(株)製)が含まれる。
The types of polymers constituting the polymer fine particles include silicone resins, fluororesins, and acrylic resins, preferably silicone resins, and more preferably silicone resins having a three-dimensional network structure. Examples of the polymer fine particles include Tospearl 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.).
なかでも、アエロジルR972V、NAX50、シーホスターKE-P30などが、得られるフィルムの濁度を低く保ちつつ、摩擦係数を低減させうるため特に好ましい。
Among them, Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because the friction coefficient can be reduced while keeping the turbidity of the obtained film low.
微粒子は、分散性を高め、得られるフィルムのヘイズの増大を少なくするためには、表面処理されていることが好ましい。表面処理剤の例には、ハロシラン類、アルコキシシラン類、シラザン、シロキサンなどが含まれる。
The fine particles are preferably subjected to a surface treatment in order to improve dispersibility and reduce an increase in the haze of the resulting film. Examples of the surface treatment agent include halosilanes, alkoxysilanes, silazane, siloxane and the like.
微粒子の一次粒子径は、5~50nmであることが好ましく、7~20nmであることがより好ましい。一次粒子径が大きいほうが、得られるフィルムの滑り性を高める効果は大きいが、透明性が低下しやすい。そのため、微粒子は、粒子径0.05~0.3μmの二次凝集体として含有されていてもよい。微粒子の一次粒子またはその二次凝集体の大きさは、透過型電子顕微鏡にて倍率50万~200万倍で一次粒子または二次凝集体を観察し、一次粒子または二次凝集体100個の粒子径の平均値として求めることができる。
The primary particle diameter of the fine particles is preferably 5 to 50 nm, more preferably 7 to 20 nm. A larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter of 0.05 to 0.3 μm. The size of the primary particles or secondary aggregates of the fine particles was determined by observing the primary particles or secondary aggregates at a magnification of 500,000 to 2,000,000 times with a transmission electron microscope, and measuring 100 primary particles or secondary aggregates. It can be determined as an average value of the particle diameter.
微粒子の含有量は、前述の樹脂成分に対して0.05~1.0質量%であることが好ましく、0.1~0.8質量%であることがより好ましい。
The content of the fine particles is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.8% by mass with respect to the resin component described above.
光学フィルムは、前述の(メタ)アクリル樹脂と酸トラップ剤とを含む組成物からなる単層フィルムであってもよいし;前述の(メタ)アクリル樹脂と酸トラップ剤とを含む組成物からなる層を含む積層フィルムであってもよい。
The optical film may be a single-layer film made of a composition containing the above-mentioned (meth) acrylic resin and an acid trapping agent; or made of a composition containing the above-mentioned (meth) acrylic resin and an acid trapping agent. It may be a laminated film including layers.
光学フィルムの物性
光学フィルムの厚みは、特に限定はされないが、20~200μmであることが好ましく、25~100μmであることがより好ましく、30~80μmであることがさらに好ましく、10~45μmであることが特に好ましい。フィルムの厚みが小さすぎると、所望のレターデーションが得られにくい。一方、フィルムの厚みが大きすぎると、湿度などの影響によってレターデーションが変動しやすい。 Physical Properties of Optical Film The thickness of the optical film is not particularly limited, but is preferably 20 to 200 μm, more preferably 25 to 100 μm, further preferably 30 to 80 μm, and more preferably 10 to 45 μm. It is particularly preferred. If the thickness of the film is too small, it is difficult to obtain a desired retardation. On the other hand, if the thickness of the film is too large, the retardation tends to fluctuate due to the influence of humidity and the like.
光学フィルムの厚みは、特に限定はされないが、20~200μmであることが好ましく、25~100μmであることがより好ましく、30~80μmであることがさらに好ましく、10~45μmであることが特に好ましい。フィルムの厚みが小さすぎると、所望のレターデーションが得られにくい。一方、フィルムの厚みが大きすぎると、湿度などの影響によってレターデーションが変動しやすい。 Physical Properties of Optical Film The thickness of the optical film is not particularly limited, but is preferably 20 to 200 μm, more preferably 25 to 100 μm, further preferably 30 to 80 μm, and more preferably 10 to 45 μm. It is particularly preferred. If the thickness of the film is too small, it is difficult to obtain a desired retardation. On the other hand, if the thickness of the film is too large, the retardation tends to fluctuate due to the influence of humidity and the like.
光学フィルムは、溶融押し出し成形法によって製造されることから、光学フィルムの残留溶媒量は0.01質量%以下であることが好ましい。
Since the optical film is produced by a melt extrusion method, the residual solvent amount of the optical film is preferably 0.01% by mass or less.
光学フィルムの残留溶媒量は、下記の方法によって測定することができる。
1)以下のガスクロマトグラフィーにて、光学フィルムの製造過程で用いた溶媒の検量線を作成する。
2)光学フィルムを粉砕して得られる試料20mlを密閉ガラス容器に入れ、ヘッドスペース加熱条件にて加熱処理する。
3)2)の加熱処理で得られた揮発成分を、検量線を参照してガスクロマトグラフィーにて定量し、光学フィルム中の残留溶媒量を測定する。残留溶媒量は、光学フィルムの全体の質量に対する質量部として表される。
機器:HP社 5890SERIES II
カラム:J&W社 DB-WAX(内径0.32mm、長さ30m)
検出:FID
GC昇温条件:40℃で5分間保持した後、80℃/分で100℃まで昇温
ヘッドスペース加熱条件:120℃で20分 The amount of residual solvent in the optical film can be measured by the following method.
1) Prepare a calibration curve of the solvent used in the optical film production process by the following gas chromatography.
2) 20 ml of a sample obtained by pulverizing the optical film is placed in a sealed glass container and heat-treated under headspace heating conditions.
3) The volatile component obtained by the heat treatment of 2) is quantified by gas chromatography with reference to a calibration curve, and the amount of residual solvent in the optical film is measured. The residual solvent amount is expressed as a part by mass with respect to the total mass of the optical film.
Equipment: HP 5890SERIES II
Column: J-W DB-WAX (inner diameter 0.32 mm, length 30 m)
Detection: FID
GC temperature rise condition: held at 40 ° C. for 5 minutes, then raised to 100 ° C. at 80 ° C./min. Headspace heating condition: 20 minutes at 120 ° C.
1)以下のガスクロマトグラフィーにて、光学フィルムの製造過程で用いた溶媒の検量線を作成する。
2)光学フィルムを粉砕して得られる試料20mlを密閉ガラス容器に入れ、ヘッドスペース加熱条件にて加熱処理する。
3)2)の加熱処理で得られた揮発成分を、検量線を参照してガスクロマトグラフィーにて定量し、光学フィルム中の残留溶媒量を測定する。残留溶媒量は、光学フィルムの全体の質量に対する質量部として表される。
機器:HP社 5890SERIES II
カラム:J&W社 DB-WAX(内径0.32mm、長さ30m)
検出:FID
GC昇温条件:40℃で5分間保持した後、80℃/分で100℃まで昇温
ヘッドスペース加熱条件:120℃で20分 The amount of residual solvent in the optical film can be measured by the following method.
1) Prepare a calibration curve of the solvent used in the optical film production process by the following gas chromatography.
2) 20 ml of a sample obtained by pulverizing the optical film is placed in a sealed glass container and heat-treated under headspace heating conditions.
3) The volatile component obtained by the heat treatment of 2) is quantified by gas chromatography with reference to a calibration curve, and the amount of residual solvent in the optical film is measured. The residual solvent amount is expressed as a part by mass with respect to the total mass of the optical film.
Equipment: HP 5890SERIES II
Column: J-W DB-WAX (inner diameter 0.32 mm, length 30 m)
Detection: FID
GC temperature rise condition: held at 40 ° C. for 5 minutes, then raised to 100 ° C. at 80 ° C./min. Headspace heating condition: 20 minutes at 120 ° C.
本発明の光学フィルムの、23℃55%RHの雰囲気下における破断応力は、それを含む偏光板のリワーク性を高めるためには、70MPa以上であることが好ましく、80MPa以上であることがより好ましい。一方、裁断(スリット)しやすくする観点から、光学フィルムの破断応力は200MPa以下であることが好ましい。
The breaking stress of the optical film of the present invention under an atmosphere of 23 ° C. and 55% RH is preferably 70 MPa or more, and more preferably 80 MPa or more, in order to enhance the reworkability of the polarizing plate containing the optical film. . On the other hand, from the viewpoint of facilitating cutting (slit), the breaking stress of the optical film is preferably 200 MPa or less.
破断応力の測定は、以下の手順で行うことができる。即ち、光学フィルムを10mm×150mmの大きさにカットし、試料片とする。この試料片について、引張り試験機(ストログラフ-R2(東洋精機製))にて、チャック間距離100mm、温度25℃、延伸速度10mm/分で引っ張り試験を行い、破断が生じるときの応力を破断応力とする。
Measure the breaking stress by the following procedure. That is, the optical film is cut into a size of 10 mm × 150 mm to obtain a sample piece. This sample piece was subjected to a tensile test with a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) at a chuck distance of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min. Let it be stress.
本発明の光学フィルムの、JIS-K7127-1999に準拠して測定される、少なくとも一方向の破断点伸度が30%以上であり、より好ましくは50%以上である。破断点伸度の上限は、現実的には250%程度である。破断点伸度を大きくするためには、溶融温度を高くし、フィルムの柔軟性を高めたり、異物や発泡に起因するフィルム中の欠陥を低減したりすればよい。
The elongation at break in at least one direction measured in accordance with JIS-K7127-1999 of the optical film of the present invention is 30% or more, more preferably 50% or more. The upper limit of the elongation at break is practically about 250%. In order to increase the elongation at break, the melting temperature is increased, the flexibility of the film is increased, or defects in the film due to foreign matter or foaming are reduced.
本発明の光学フィルムの、23℃55%RHの雰囲気下における引き裂き強度は、それを含む偏光板のリワーク性を高めるためには、10mN以上であることが好ましく、20mN以上であることがより好ましい。一方、裁断(スリット)しやすくする観点から、光学フィルムの引き裂き強度は100mN以下であることが好ましい。
The tear strength of the optical film of the present invention in an atmosphere of 23 ° C. and 55% RH is preferably 10 mN or more, more preferably 20 mN or more in order to improve the reworkability of the polarizing plate containing the optical film. . On the other hand, from the viewpoint of facilitating cutting (slit), the tear strength of the optical film is preferably 100 mN or less.
引き裂き強度の測定は、以下のようにして行うことができる。即ち、光学フィルムを、65mm×50mmの大きさにカットし、試料片とする。この試料片の、エレメンドルフ法による引き裂き荷重を、JIS K 7128-1991に準拠して、東洋精機(株)製の軽荷重引き裂き装置にて測定する。
Tear strength can be measured as follows. That is, the optical film is cut into a size of 65 mm × 50 mm to obtain a sample piece. The tear load of this sample piece by the Elmendorf method is measured with a light load tear device manufactured by Toyo Seiki Co., Ltd. according to JIS K-7128-1991.
光学フィルムの、23℃、55%RHの環境下で、波長590nmにて測定される面内方向のレターデーションRoは-5nm~5nmの範囲であることが好ましく、-3nm~3nmの範囲であることがより好ましい。厚み方向のレターデーションRthは-5nm~5nmの範囲であることが好ましく、-3nm~3nmの範囲であることがより好ましい。
The retardation Ro in the in-plane direction measured at a wavelength of 590 nm under the environment of 23 ° C. and 55% RH of the optical film is preferably in the range of −5 nm to 5 nm, and in the range of −3 nm to 3 nm. It is more preferable. The retardation Rth in the thickness direction is preferably in the range of −5 nm to 5 nm, and more preferably in the range of −3 nm to 3 nm.
レターデーションR0およびRthは、それぞれ以下の式で表される。
式(I) R0=(nx-ny)×d
式(II) Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向の屈折率、ny:フィルム面内において、遅相軸に対して直交する方向の屈折率、nz:厚み方向におけるフィルムの屈折率、d:フィルムの厚み(nm)) Retardation R0 and Rth are each represented by the following formula.
Formula (I) R 0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))
式(I) R0=(nx-ny)×d
式(II) Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向の屈折率、ny:フィルム面内において、遅相軸に対して直交する方向の屈折率、nz:厚み方向におけるフィルムの屈折率、d:フィルムの厚み(nm)) Retardation R0 and Rth are each represented by the following formula.
Formula (I) R 0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))
レターデーションR0およびRthは、例えば以下の方法によって求めることができる。
1)フィルムの平均屈折率を屈折計により測定する。
2)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向からの波長590nmの光を入射させたときの面内方向のレターデーションR0を測定する。
3)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向に対してθの角度(入射角(θ))から波長590nmの光を入射させたときのレターデーション値R(θ)を測定する。θは0°よりも大きく、好ましくは30°~50°である。
4)測定されたR0およびR(θ)と、前述の平均屈折率と膜厚とから、王子計測機器社製KOBRA-21ADHにより、nx、nyおよびnzを算出し、Rthを算出する。レターデーションの測定は、23℃55%RH条件下で行うことができる。 The retardations R0 and Rth can be determined by the following method, for example.
1) The average refractive index of the film is measured with a refractometer.
2) The retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the normal direction of the film is incident is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
3) The retardation value R (θ) when light having a wavelength of 590 nm is incident from the angle θ (incident angle (θ)) with respect to the normal direction of the film is measured with KOBRA-21ADH manufactured by Oji Scientific Instruments. . θ is larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R 0 and R (θ) and the above-mentioned average refractive index and film thickness, nx, ny and nz are calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.
1)フィルムの平均屈折率を屈折計により測定する。
2)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向からの波長590nmの光を入射させたときの面内方向のレターデーションR0を測定する。
3)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向に対してθの角度(入射角(θ))から波長590nmの光を入射させたときのレターデーション値R(θ)を測定する。θは0°よりも大きく、好ましくは30°~50°である。
4)測定されたR0およびR(θ)と、前述の平均屈折率と膜厚とから、王子計測機器社製KOBRA-21ADHにより、nx、nyおよびnzを算出し、Rthを算出する。レターデーションの測定は、23℃55%RH条件下で行うことができる。 The retardations R0 and Rth can be determined by the following method, for example.
1) The average refractive index of the film is measured with a refractometer.
2) The retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the normal direction of the film is incident is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
3) The retardation value R (θ) when light having a wavelength of 590 nm is incident from the angle θ (incident angle (θ)) with respect to the normal direction of the film is measured with KOBRA-21ADH manufactured by Oji Scientific Instruments. . θ is larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R 0 and R (θ) and the above-mentioned average refractive index and film thickness, nx, ny and nz are calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.
光学フィルムの面内遅相軸とフィルムの幅方向とのなす角θ1(配向角)は、-5°以上+5°以下であることが好ましく、-1°以上+1°以下であることがより好ましい。光学フィルムの配向角θ1の測定は、自動複屈折計KOBRA-21ADH(王子計測機器)を用いて測定することができる。
The angle θ1 (orientation angle) formed by the in-plane slow axis of the optical film and the width direction of the film is preferably −5 ° or more and + 5 ° or less, and more preferably −1 ° or more and + 1 ° or less. . The orientation angle θ1 of the optical film can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).
光学フィルムの、JIS K-7136に準拠して測定されるヘイズは、液晶表示装置において十分な輝度や高いコントラストを得るためには、0.5%以下であることがより好ましく、0.35%以下であることがさらに好ましく、0.05%以下であることが特に好ましい。光学フィルムのヘイズを低くするためには、溶融温度を高くしたり、セルロースエステルの炭素数3~7のアシル基の置換度を高めたりすればよい。
The haze of the optical film measured according to JIS K-7136 is more preferably 0.5% or less in order to obtain sufficient brightness and high contrast in a liquid crystal display device, and 0.35% More preferably, it is more preferably 0.05% or less. In order to reduce the haze of the optical film, the melting temperature may be increased or the substitution degree of the acyl group having 3 to 7 carbon atoms of the cellulose ester may be increased.
光学フィルムのヘイズは、JIS K-7136に準拠した方法;具体的には、以下の方法で測定することができる。
1)得られた光学フィルムを、23℃55%RH下で5時間以上調湿する。その後、フィルムの表面に付着したホコリなどをブロワーなどで除去する。
2)次いで、光学フィルムのヘイズを、23℃55%RHの条件下にて、ヘイズメーター(濁度計)(型式:NDH 2000、日本電色(株)製)にて測定する。ヘイズメーターの光源は、5V9Wのハロゲン球とし、受光部は、シリコンフォトセル(比視感度フィルター付き)としうる。 The haze of the optical film can be measured by a method according to JIS K-7136; specifically, the following method.
1) The obtained optical film is conditioned at 23 ° C. and 55% RH for 5 hours or more. Thereafter, dust attached to the surface of the film is removed with a blower or the like.
2) Next, the haze of the optical film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) under the condition of 23 ° C. and 55% RH. The light source of the haze meter may be a 5V9W halogen sphere, and the light receiving part may be a silicon photocell (with a relative visibility filter).
1)得られた光学フィルムを、23℃55%RH下で5時間以上調湿する。その後、フィルムの表面に付着したホコリなどをブロワーなどで除去する。
2)次いで、光学フィルムのヘイズを、23℃55%RHの条件下にて、ヘイズメーター(濁度計)(型式:NDH 2000、日本電色(株)製)にて測定する。ヘイズメーターの光源は、5V9Wのハロゲン球とし、受光部は、シリコンフォトセル(比視感度フィルター付き)としうる。 The haze of the optical film can be measured by a method according to JIS K-7136; specifically, the following method.
1) The obtained optical film is conditioned at 23 ° C. and 55% RH for 5 hours or more. Thereafter, dust attached to the surface of the film is removed with a blower or the like.
2) Next, the haze of the optical film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) under the condition of 23 ° C. and 55% RH. The light source of the haze meter may be a 5V9W halogen sphere, and the light receiving part may be a silicon photocell (with a relative visibility filter).
光学フィルムの可視光透過率は、90%以上であることが好ましく、92%以上であることがより好ましい。
The visible light transmittance of the optical film is preferably 90% or more, and more preferably 92% or more.
本発明の光学フィルムは、スジ状欠陥を有しないことが好ましい。スジ状欠陥とは、光学フィルム表面の、フィルム長手方向に伸びたスジであって、フィルム幅方向断面におけるスジの高さ(スジの山の頂点から谷の底点までの高さ)が300nm以上であり、かつスジの傾きが300nm/mm以上であるものである。
The optical film of the present invention preferably has no streak-like defects. A streak-like defect is a streak extending in the longitudinal direction of the film on the optical film surface, and the height of the streak in the film width direction cross section (height from the top of the streak peak to the bottom of the valley) is 300 nm or more. And the streak slope is 300 nm / mm or more.
スジ状欠陥の形状は、以下の手順で測定することができる。
1)ミツトヨ製SV-3100S4を用いて、先端形状が円錐60°、先端曲率半径2μmの触針(ダイヤモンド針)に測定力0.75mNの加重をかけながら、測定速度1.0mm/secでフィルム幅方向に走査し、Z軸(厚み方向)分解能0.001μmとして、フィルム幅方向の断面曲線を測定する。
2)得られた断面曲線から、スジの山の頂点と谷の底点との垂直距離(H)を読み取って、スジの高さとする。また、山の頂点と谷の底点との水平距離(L)を読み取り、垂直距離(H)を水平距離(L)で除して得られる値を、スジの傾きとする。 The shape of the streak defect can be measured by the following procedure.
1) Using Mitutoyo SV-3100S4, film is applied at a measuring speed of 1.0 mm / sec while applying a measuring force of 0.75 mN to a stylus (diamond needle) having a tip shape of 60 ° cone and a radius of curvature of 2 μm. Scan in the width direction and measure the cross-sectional curve in the film width direction with a Z-axis (thickness direction) resolution of 0.001 μm.
2) From the obtained cross-sectional curve, the vertical distance (H) between the top of the streak peak and the bottom point of the trough is read and set as the streak height. Also, the horizontal distance (L) between the peak of the mountain and the bottom of the valley is read, and the value obtained by dividing the vertical distance (H) by the horizontal distance (L) is defined as the slope of the stripe.
1)ミツトヨ製SV-3100S4を用いて、先端形状が円錐60°、先端曲率半径2μmの触針(ダイヤモンド針)に測定力0.75mNの加重をかけながら、測定速度1.0mm/secでフィルム幅方向に走査し、Z軸(厚み方向)分解能0.001μmとして、フィルム幅方向の断面曲線を測定する。
2)得られた断面曲線から、スジの山の頂点と谷の底点との垂直距離(H)を読み取って、スジの高さとする。また、山の頂点と谷の底点との水平距離(L)を読み取り、垂直距離(H)を水平距離(L)で除して得られる値を、スジの傾きとする。 The shape of the streak defect can be measured by the following procedure.
1) Using Mitutoyo SV-3100S4, film is applied at a measuring speed of 1.0 mm / sec while applying a measuring force of 0.75 mN to a stylus (diamond needle) having a tip shape of 60 ° cone and a radius of curvature of 2 μm. Scan in the width direction and measure the cross-sectional curve in the film width direction with a Z-axis (thickness direction) resolution of 0.001 μm.
2) From the obtained cross-sectional curve, the vertical distance (H) between the top of the streak peak and the bottom point of the trough is read and set as the streak height. Also, the horizontal distance (L) between the peak of the mountain and the bottom of the valley is read, and the value obtained by dividing the vertical distance (H) by the horizontal distance (L) is defined as the slope of the stripe.
本発明の光学フィルムに含まれる(メタ)アクリル樹脂とセルロースエステルとは、相溶していることが好ましい。(メタ)アクリル樹脂とセルロースエステルとが相溶しているかどうかは、例えば光学フィルムのガラス転移温度Tgによって確認されうる。例えば、(メタ)アクリル樹脂とセルロースエステルとが相溶している光学フィルムのガラス転移温度は、それぞれの樹脂に由来するガラス転移温度は確認されず、1つのガラス転移温度のみが確認される。
The (meth) acrylic resin and cellulose ester contained in the optical film of the present invention are preferably compatible with each other. Whether or not the (meth) acrylic resin and the cellulose ester are compatible can be confirmed by, for example, the glass transition temperature Tg of the optical film. For example, as for the glass transition temperature of the optical film in which the (meth) acrylic resin and the cellulose ester are compatible, the glass transition temperature derived from each resin is not confirmed, and only one glass transition temperature is confirmed.
ガラス転移温度は、示差走査熱量測定器(Perkin Elmer社製DSC-7型)を用いて、JIS K7121(1987)に準拠した方法にて、中間点ガラス転移温度(Tmg)として測定される。昇温速度は20℃/分としうる。
The glass transition temperature is measured as a midpoint glass transition temperature (Tmg) by a method based on JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer). The heating rate can be 20 ° C./min.
本発明の光学フィルムは、必要に応じて他の機能層(接着層、染料層、帯電防止層、アンチハレーション層、UV吸収層、偏光層など)をさらに有していてもよい。
The optical film of the present invention may further have other functional layers (an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorption layer, a polarizing layer, etc.) as necessary.
本発明の光学フィルムは、液晶表示装置の偏光板保護フィルム、位相差フィルム、反射防止フィルム、輝度向上フィルム、ハードコートフィルム、防眩フィルム、帯電防止フィルム、視野角拡大用の光学補償フィルムなどとして好ましく用いることができる。偏光板保護フィルムには、例えば位相差調整機能や光学補償機能などをさらに有する保護フィルムなども含まれる。
The optical film of the present invention is a polarizing plate protective film, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for widening the viewing angle, etc. for liquid crystal display devices. It can be preferably used. Examples of the polarizing plate protective film include a protective film further having a retardation adjustment function, an optical compensation function, and the like.
2.光学フィルムの製造方法
本発明の光学フィルムは、前述の(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を加熱溶融した後、流延して製膜する方法(溶融製膜法)によって得ることができる。溶融製膜法の例には、溶融押出し成形法、プレス成形法、インフレーション法、射出成形法、ブロー成形法、延伸成形法などがあるが、表面精度などが高いフィルムが得られやすいことから、溶融押出し成形法が好ましい。即ち、本発明の光学フィルムは、(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を溶融混練した後、押し出すステップを経て得ることができる。 2. Manufacturing method of optical film The optical film of the present invention is a method in which the resin composition containing the (meth) acrylic resin and the acid trapping agent is heated and melted, and then cast and formed (melting film forming method). Can be obtained by: Examples of the melt film forming method include a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretch molding method. A melt extrusion method is preferred. That is, the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent.
本発明の光学フィルムは、前述の(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を加熱溶融した後、流延して製膜する方法(溶融製膜法)によって得ることができる。溶融製膜法の例には、溶融押出し成形法、プレス成形法、インフレーション法、射出成形法、ブロー成形法、延伸成形法などがあるが、表面精度などが高いフィルムが得られやすいことから、溶融押出し成形法が好ましい。即ち、本発明の光学フィルムは、(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を溶融混練した後、押し出すステップを経て得ることができる。 2. Manufacturing method of optical film The optical film of the present invention is a method in which the resin composition containing the (meth) acrylic resin and the acid trapping agent is heated and melted, and then cast and formed (melting film forming method). Can be obtained by: Examples of the melt film forming method include a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretch molding method. A melt extrusion method is preferred. That is, the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent.
まず、溶融押し出し法に用いられる、フィルムの製造装置について説明する。図1は、フィルムの製造装置の一例を示す模式図である。図1に示されるように、フィルムの製造装置10は、樹脂を溶融混練する押し出し機12と、溶融した樹脂をフィルム状に吐出するダイ14と、ダイ14から吐出された高温の樹脂を多段冷却する第1、第2および第3冷却ロール16、18および20と、冷却固化されて得られるフィルムを剥離する剥離ロール22と、フィルムを延伸する延伸装置24と、延伸されたフィルムを巻き取る巻き取り装置26とを有する。
First, a film manufacturing apparatus used in the melt extrusion method will be described. FIG. 1 is a schematic diagram illustrating an example of a film manufacturing apparatus. As shown in FIG. 1, a film manufacturing apparatus 10 includes an extruder 12 that melts and kneads a resin, a die 14 that discharges the molten resin into a film, and multi-stage cooling of the high-temperature resin discharged from the die 14. The first, second and third cooling rolls 16, 18 and 20, the peeling roll 22 for peeling the film obtained by cooling and solidification, the stretching device 24 for stretching the film, and the winding for winding the stretched film A take-off device 26.
押し出し機12は、溶融混練押し出し機であり、シリンダと、その内部に回転自在に設けられたスクリューとを有する。シリンダの供給口には、フィルムの材料を供給するためのホッパー(不図示)が設けられている。スクリューの形状は、フルフライト、マドック、ダルメージなどであってよく、溶融樹脂の粘度や必要とされるせん断力に応じて選択される。押し出し機12は、1軸押し出し機であっても、2軸押し出し機であってもよい。
The extruder 12 is a melt-kneading extruder, and has a cylinder and a screw rotatably provided therein. A hopper (not shown) for supplying film material is provided at the supply port of the cylinder. The shape of the screw may be full flight, mudock, dull mage, etc., and is selected according to the viscosity of the molten resin and the required shearing force. The extruder 12 may be a single screw extruder or a twin screw extruder.
押し出し機12とダイ14との間には、溶融樹脂をろ過するフィルタ28がさらに設けられてもよい。フィルタ28は、例えばリーフディスクタイプのフィルタであり、好ましくはステンレス繊維焼結フィルタである。フィルタの濾過精度は、3~15μmmであることが好ましい。フィルタ28は、異物やゲルなどの捕捉精度を高める観点などから、ろ過精度の異なるろ過材の多層体であることが好ましい。
A filter 28 for filtering the molten resin may be further provided between the extruder 12 and the die 14. The filter 28 is, for example, a leaf disk type filter, and is preferably a stainless fiber sintered filter. The filtration accuracy of the filter is preferably 3 to 15 μmm. The filter 28 is preferably a multilayer body of filtration media having different filtration accuracy from the viewpoint of increasing the accuracy of capturing foreign substances or gels.
押し出し機12とダイ14との間には、樹脂を均一に混合するためのスタチックミキサ30などの混合装置や、押出し流量を安定化するためのギアポンプ(不図示)などがさらに設けられてもよい。
Between the extruder 12 and the die 14, a mixing device such as a static mixer 30 for uniformly mixing the resin, a gear pump (not shown) for stabilizing the extrusion flow rate, and the like may be further provided. Good.
ダイ14は、公知のものであってよく、Tダイなどである。ダイ14本体の材質は、ハードクロム、炭化クロム、窒化クロム、炭化チタン、炭窒化チタン、窒化チタン、超鋼、セラミック(タングステンカーバイド、酸化アルミ、酸化クロム)などを溶射もしくはメッキした後;バフ、平面切削、電解研磨などの表面加工をさらに施したものでありうる。ダイ14のリップ部の材質は、ダイ本体と同様としうる。ダイ14のリップ部の表面精度は0.5S以下が好ましく、0.2S以下がより好ましい。
The die 14 may be a known one, such as a T die. The material of the die 14 body is sprayed or plated with hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc .; buff, It may further be subjected to surface processing such as plane cutting or electrolytic polishing. The material of the lip portion of the die 14 can be the same as that of the die body. The surface accuracy of the lip portion of the die 14 is preferably 0.5S or less, and more preferably 0.2S or less.
ダイ14のスリットは、そのギャップが調整可能に構成されている。ダイ14のスリットを形成する一対のリップのうち、一方は剛性が低く、変形しやすいフレキシブルリップであり、他方は固定リップであることが、スリットのギャップを調整しやすいことから好ましい。スリットのギャップ(ダイリップクリアランス)は、好ましくは900μm以上であり、より好ましくは1mm以上2mm以下である。ダイリップクリアランスが上記範囲外であると、得られるフィルムに斑点状のムラが生じやすい。
The slit of the die 14 is configured such that the gap can be adjusted. Of the pair of lips forming the slit of the die 14, one is a flexible lip having low rigidity and is easily deformed, and the other is preferably a fixed lip because the slit gap can be easily adjusted. The slit gap (die lip clearance) is preferably 900 μm or more, and more preferably 1 mm or more and 2 mm or less. When the die lip clearance is out of the above range, spotted unevenness tends to occur in the obtained film.
ダイ14の内壁面に、傷や可塑剤の凝結物などの異物が付着すると、押し出される溶融樹脂の表面にスジ状の欠陥(ダイライン)が生じることがある。ダイラインなどの表面欠陥を低減するためには、押し出し機12からダイ14の先端までの内壁面には、樹脂の滞留部が付着しにくい構造にすること;例えば押し出し機12からダイ14の先端までの内壁面には、傷などがないことが好ましい。
When foreign matter such as scratches or agglomerated plasticizer adheres to the inner wall surface of the die 14, a streak-like defect (die line) may occur on the surface of the extruded molten resin. In order to reduce surface defects such as die lines, the inner wall surface from the extruder 12 to the tip of the die 14 should have a structure in which a resin staying portion is difficult to adhere; for example, from the extruder 12 to the tip of the die 14 It is preferable that the inner wall surface is not scratched.
押し出し機12やダイ14などの内壁面は、溶融樹脂が付着しにくくするために、表面粗さを小さくする、または表面エネルギーを低くする表面加工が施されていることが好ましい。そのような表面加工の例には、ハードクロムメッキやセラミック溶射した後、表面粗さ0.2S以下となるように研磨する加工が含まれる。
The inner wall surfaces of the extruder 12 and the die 14 are preferably subjected to surface processing for reducing the surface roughness or reducing the surface energy in order to make the molten resin difficult to adhere. Examples of such surface processing include processing for polishing to have a surface roughness of 0.2 S or less after hard chrome plating or ceramic spraying.
第1冷却ロール16、第2冷却ロール18および第3冷却ロール20は、高剛性の金属ロールであり、内部に温度制御可能な媒体を流通できる構造を有する。冷却ロール16、18および20の表面の材質は、ステンレス、アルミニウム、チタンなどでありうる。冷却ロール16、18および20の表面には、樹脂を剥離しやすくしたりするためなどから、ハードクロムメッキなどの表面処理を施してもよい。冷却ロール16、18および20の表面の粗さRaは、得られるフィルムのヘイズを低く維持するために、0.1μm以下とすることが好ましく、0.05μm以下とすることがより好ましい。
The first cooling roll 16, the second cooling roll 18, and the third cooling roll 20 are high-rigidity metal rolls, and have a structure in which a temperature-controllable medium can be circulated. The material of the surface of the cooling rolls 16, 18 and 20 can be stainless steel, aluminum, titanium or the like. The surface of the cooling rolls 16, 18 and 20 may be subjected to a surface treatment such as hard chrome plating in order to make the resin easy to peel off. The surface roughness Ra of the cooling rolls 16, 18, and 20 is preferably 0.1 μm or less, and more preferably 0.05 μm or less, in order to keep the haze of the resulting film low.
弾性タッチロール32は、冷却ロール16と対向して配置されている。そして、ダイ14から押し出された溶融樹脂が、冷却ロール16と弾性タッチロール32とでニップされるようになっている。弾性タッチロール32は、特開平03-124425号、特開平08-224772号、特開平07-100960号などに記載の、薄膜金属スリーブで被覆されたシリコンゴムロールなどが用いられる。
The elastic touch roll 32 is disposed to face the cooling roll 16. The molten resin extruded from the die 14 is nipped between the cooling roll 16 and the elastic touch roll 32. As the elastic touch roll 32, a silicon rubber roll covered with a thin metal sleeve as described in JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096 and the like is used.
延伸装置24は、特に制限されないが、ロール延伸機、テンター延伸機などが好ましく用いられる。ロール延伸機とテンター延伸機とを組み合わせてもよい。テンター延伸機は、予熱ゾーン、延伸ゾーン、保持ゾーン、冷却ゾーンを有するものが好ましく、各ゾーン間に、各ゾーン間を断熱するためのニュートラルゾーンをさらに有するものが好ましい。
The stretching device 24 is not particularly limited, but a roll stretching machine, a tenter stretching machine or the like is preferably used. A roll stretching machine and a tenter stretching machine may be combined. The tenter stretching machine preferably has a preheating zone, a stretching zone, a holding zone, and a cooling zone, and preferably has a neutral zone for insulating between the zones.
製造装置10における各種ロールには、ロール表面を清掃する機構がさらに設けられていてもよい。ロール清掃方式の例には、ブラシ・ロール、吸水ロール、粘着ロール、ふき取りロールなどをニップする方式、清浄エアーを吹き掛けるエアーブロー方式、レーザーによる焼却方式あるいはこれらの組み合わせなどでありうる。
The various rolls in the manufacturing apparatus 10 may be further provided with a mechanism for cleaning the roll surface. Examples of the roll cleaning method may include a method of niping a brush roll, a water absorption roll, an adhesive roll, a wiping roll, an air blow method of spraying clean air, a laser incineration method, or a combination thereof.
次に、フィルムの製造装置10を用いて光学フィルムを得るステップを説明する。本発明の光学フィルムは、例えば前述の樹脂組成物からなるペレットを準備する工程(ペレット化工程);ペレットを含むフィルム材料を、押し出し機12にて溶融混練した後、ダイ14から押し出す工程(溶融押出工程);押し出された溶融樹脂を冷却固化してフィルムを得る工程(冷却固化工程);フィルムを延伸する工程(延伸工程)、を経て得ることができる。
Next, a step of obtaining an optical film using the film manufacturing apparatus 10 will be described. The optical film of the present invention is, for example, a step of preparing pellets made of the resin composition described above (pelletizing step); It can be obtained through a step of cooling and solidifying the extruded molten resin to obtain a film (cooling and solidifying step); a step of stretching the film (stretching step).
1)ペレット化工程
前述の(メタ)アクリル樹脂と酸トラップ剤とを含む樹脂組成物は、あらかじめ混練してペレット化しておくことが好ましい。ペレット化は、公知の方法で行うことができ、例えば前述の樹脂組成物を押し出し機にて溶融混錬した後、ダイからストランド状に押し出す。ストランド状に押し出された溶融樹脂を、水冷または空冷した後、カッティングしてペレットを得ることができる。 1) Pelletization process It is preferable that the resin composition containing the (meth) acrylic resin and the acid trapping agent is previously kneaded and pelletized. Pelletization can be performed by a known method. For example, the above resin composition is melt-kneaded with an extruder and then extruded from a die in a strand shape. The molten resin extruded in a strand shape can be cooled with water or air, and then cut to obtain pellets.
前述の(メタ)アクリル樹脂と酸トラップ剤とを含む樹脂組成物は、あらかじめ混練してペレット化しておくことが好ましい。ペレット化は、公知の方法で行うことができ、例えば前述の樹脂組成物を押し出し機にて溶融混錬した後、ダイからストランド状に押し出す。ストランド状に押し出された溶融樹脂を、水冷または空冷した後、カッティングしてペレットを得ることができる。 1) Pelletization process It is preferable that the resin composition containing the (meth) acrylic resin and the acid trapping agent is previously kneaded and pelletized. Pelletization can be performed by a known method. For example, the above resin composition is melt-kneaded with an extruder and then extruded from a die in a strand shape. The molten resin extruded in a strand shape can be cooled with water or air, and then cut to obtain pellets.
紫外線吸収剤または微粒子(マット剤)などは、前述の樹脂組成物からなるメインペレットに含まれていても、前述の樹脂組成物とは別の高濃度のマスターペレットに含まれてもよい。
The ultraviolet absorber or fine particles (matting agent) may be contained in the main pellet made of the above resin composition, or may be contained in a high concentration master pellet different from the above resin composition.
ペレットの原材料は、分解を防止するために、押し出し機に供給する前に乾燥しておくことが好ましい。例えば、セルロースエステルは吸湿しやすいため、70~140℃で3時間以上乾燥させて、水分率を200ppm以下、好ましくは100ppm以下にしておくことが好ましい。
The raw material of the pellet is preferably dried before being supplied to the extruder in order to prevent decomposition. For example, since the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more so that the water content is 200 ppm or less, preferably 100 ppm or less.
押し出し機に供給される複数種の添加剤は、予め混合されていてもよいし、混合されていなくてもよい。酸化防止剤などの少量の添加剤は、均一に混合するために、押し出し機に供給される前に予め混合されていることが好ましい。原材料の混合は、原材料の乾燥と混合を同時に行うことができることから、真空ナウターミキサーで行うことが好ましい。また、押し出し機のホッパー付近やダイの出口付近の雰囲気は、ペレットの原材料の劣化を防止するためなどから、除湿した空気またはN2ガスなどの雰囲気とすることが好ましい。また、押し出し機のホッパーなどは、原材料の吸湿を防止するためなどから、保温しておくことが好ましい。
The plural types of additives supplied to the extruder may be mixed in advance or may not be mixed. A small amount of an additive such as an antioxidant is preferably mixed in advance before being supplied to the extruder in order to mix uniformly. Since the raw materials can be dried and mixed at the same time, the raw materials are preferably mixed with a vacuum nauter mixer. In addition, the atmosphere near the hopper of the extruder or the exit of the die is preferably an atmosphere of dehumidified air or N 2 gas in order to prevent deterioration of the raw material of the pellet. The hopper of the extruder is preferably kept warm to prevent moisture absorption of the raw materials.
押し出し機12では、樹脂の劣化(分子量の低下、着色およびゲル状異物の生成など)が生じないように、低いせん断力または低い温度で混練することが好ましい。例えば、2軸押し出し機で混練する場合、深溝タイプのスクリューを用いて、2つのスクリューの回転方向を同方向にすることが好ましい。均一に混錬するためには、2つのスクリュー形状が互いに噛み合うようにすることが好ましい。
The extruder 12 is preferably kneaded at a low shearing force or at a low temperature so as not to cause deterioration of the resin (decrease in molecular weight, coloring, generation of gel-like foreign matters, etc.). For example, when kneading with a twin screw extruder, it is preferable to use a deep groove type screw and to rotate the two screws in the same direction. In order to knead uniformly, it is preferable that two screw shapes mesh with each other.
ペレットの色は、黄味の指標であるb*値が-5~10の範囲にあることが好ましく、-1~8の範囲にあることがさらに好ましく、-1~5の範囲にあることがより好ましい。b*値は、分光測色計CM-3700d(コニカミノルタセンシング(株)製)にて、光源をD65(色温度6504K)とし、視野角を10°として測定することができる。
As for the color of the pellet, the b * value as an index of yellowness is preferably in the range of -5 to 10, more preferably in the range of -1 to 8, and preferably in the range of -1 to 5. More preferred. The b * value can be measured with a spectrocolorimeter CM-3700d (manufactured by Konica Minolta Sensing Co., Ltd.) with a light source of D65 (color temperature 6504K) and a viewing angle of 10 °.
樹脂組成物をペレット化せずに、溶融混練していない樹脂組成物をそのまま原料として押し出し機12にて溶融混練して光学フィルムを製造してもよい。
Instead of pelletizing the resin composition, an optical film may be produced by melting and kneading the resin composition not melt-kneaded as a raw material with the extruder 12 as it is.
2)溶融押出し工程
ペレットなどのフィルム材料は、予め乾燥させておくことが好ましい。真空または減圧乾燥機や除湿熱風乾燥機などで、ペレットなどの材料に含まれる水分量を200ppm以下、好ましくは100ppm以下となるまで乾燥させておくことが好ましい。 2) Melt extrusion process It is preferable to dry film materials such as pellets in advance. It is preferable to dry it until the amount of water contained in the material such as pellets is 200 ppm or less, preferably 100 ppm or less, using a vacuum or a vacuum dryer or a dehumidifying hot air dryer.
ペレットなどのフィルム材料は、予め乾燥させておくことが好ましい。真空または減圧乾燥機や除湿熱風乾燥機などで、ペレットなどの材料に含まれる水分量を200ppm以下、好ましくは100ppm以下となるまで乾燥させておくことが好ましい。 2) Melt extrusion process It is preferable to dry film materials such as pellets in advance. It is preferable to dry it until the amount of water contained in the material such as pellets is 200 ppm or less, preferably 100 ppm or less, using a vacuum or a vacuum dryer or a dehumidifying hot air dryer.
ペレットを含むフィルム材料を、ホッパー(不図示)から押し出し機12に供給する。ペレットの供給は、ペレットの酸化分解を防止するためなどから、真空下、減圧下または不活性ガス雰囲気下で行うことが好ましい。そして、押し出し機12にて、ペレットを含むフィルム材料を溶融混練する。
The film material containing pellets is supplied to the extruder 12 from a hopper (not shown). The supply of pellets is preferably performed under vacuum, reduced pressure, or an inert gas atmosphere in order to prevent oxidative decomposition of the pellets. And the film material containing a pellet is melt-kneaded in the extruder 12.
押し出し機12内のフィルム材料の溶融温度は、フィルム材料の種類、溶融物の粘度や吐出量、得られるフィルム厚みなどにもよるが、フィルムのガラス転移温度をTg℃としたときに、好ましくはTg℃~(Tg+150)℃の範囲であり、より好ましくは(Tg+50)℃~(Tg+130)℃の範囲である。具体的には、(メタ)アクリル樹脂/セルロースエステルの混合物の場合、溶融温度は、150~300℃程度であり、好ましくは200~270℃であり、より好ましくは240~270℃であり、さらに好ましくは260~270℃である。溶融温度が低すぎると、フィルム材料が十分に混練されなかったりし、溶融温度が高すぎると、フィルム材料が熱劣化することがある。
The melting temperature of the film material in the extruder 12 depends on the type of the film material, the viscosity and discharge amount of the melt, the thickness of the obtained film, etc., but preferably when the glass transition temperature of the film is Tg ° C. It is in the range of Tg ° C. to (Tg + 150) ° C., more preferably in the range of (Tg + 50) ° C. to (Tg + 130) ° C. Specifically, in the case of a (meth) acrylic resin / cellulose ester mixture, the melting temperature is about 150 to 300 ° C, preferably 200 to 270 ° C, more preferably 240 to 270 ° C, The temperature is preferably 260 to 270 ° C. If the melting temperature is too low, the film material may not be sufficiently kneaded, and if the melting temperature is too high, the film material may be thermally deteriorated.
リワーク性の高い光学フィルム;具体的には、柔軟性の高い光学フィルムを得るためには、溶融温度を高くして、溶融樹脂の流動性を高めることが有効と考えられる。しかしながら、溶融温度を高くすると樹脂が熱劣化しやすいため、得られるフィルムが着色していたり、脆くなったり、所望の光学特性を満たさなかったりする。
Highly reworkable optical film; Specifically, in order to obtain a highly flexible optical film, it is considered effective to increase the melt temperature and increase the fluidity of the molten resin. However, if the melting temperature is increased, the resin is likely to be thermally deteriorated, so that the resulting film is colored, becomes brittle, or does not satisfy desired optical properties.
溶融温度を高くしたときの、樹脂の熱劣化が生じるメカニズムは、必ずしも明らかではないものの、原料である(メタ)アクリル樹脂に残留するモノマーが熱分解して酸を発生し、この酸が、樹脂を熱劣化させるためであると推測される。溶融温度を高くしたときの樹脂の熱劣化は、特に樹脂組成物が(メタ)アクリル樹脂とセルロースエステルを含有する場合に特に生じやすい。セルロースエステルのエステル部が加水分解して酸を発生し、この酸も樹脂を熱劣化させるためであると推測される。
The mechanism of thermal degradation of the resin when the melting temperature is increased is not necessarily clear, but the monomer remaining in the raw material (meth) acrylic resin is thermally decomposed to generate an acid, and this acid is the resin. This is presumed to cause thermal degradation of the material. Thermal degradation of the resin when the melting temperature is increased is particularly likely to occur particularly when the resin composition contains a (meth) acrylic resin and a cellulose ester. It is presumed that the ester portion of the cellulose ester is hydrolyzed to generate an acid, which also causes the resin to thermally deteriorate.
本発明では、(メタ)アクリル樹脂を含有する樹脂組成物が、酸トラップ剤をさらに含有する。酸トラップ剤は、特に溶融温度を高くしたときに、樹脂成分を分解させる酸をトラップしうる。それにより、溶融温度を高くしても、樹脂を熱劣化させることなく溶融混練することができる。
In the present invention, the resin composition containing a (meth) acrylic resin further contains an acid trapping agent. The acid trapping agent can trap an acid that decomposes the resin component, particularly when the melting temperature is increased. Thereby, even if the melting temperature is increased, the resin can be melt-kneaded without causing thermal degradation.
押し出し機12内におけるフィルム材料の溶融粘度は、1~10000Pa・sであることが好ましく、10~1000Pa・sであることがより好ましい。溶融物の溶融粘度が高すぎると、圧力が上昇するため、押し出し機12内での滞留時間が長くなりやすい。押し出し機12内でのフィルム材料の滞留時間は、短いことが好ましく、5分以内程度、好ましくは3分以内、より好ましくは2分以内である。滞留時間は、フィルム材料の供給量、シリンダの内径(D)に対するシリンダの長さ(L)の比であるL/D、スクリューの回転数またはスクリューの溝の深さなどによって調整することができる。
The melt viscosity of the film material in the extruder 12 is preferably 1 to 10,000 Pa · s, and more preferably 10 to 1000 Pa · s. When the melt viscosity of the melt is too high, the pressure rises, so that the residence time in the extruder 12 tends to be long. The residence time of the film material in the extruder 12 is preferably short, preferably within about 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes. The residence time can be adjusted by the supply amount of the film material, L / D which is the ratio of the cylinder length (L) to the cylinder inner diameter (D), the number of rotations of the screw or the depth of the groove of the screw. .
押し出し機12のスクリューの回転数や形状は、フィルム材料の溶融粘度や吐出量などによって適宜選択される。押し出し機12でのせん断速度は、1/秒~10000/秒、好ましくは5/秒~1000/秒、より好ましくは10/秒~100/秒である。
The screw rotation speed and shape of the extruder 12 are appropriately selected depending on the melt viscosity and the discharge amount of the film material. The shear rate in the extruder 12 is 1 / second to 10,000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second.
押し出し機12から押し出された溶融樹脂を、必要に応じてフィルタ28などでろ過した後、スタチックミキサ30などでさらに混合して、ダイ14からフィルム状に押し出す。ダイ14の出口部分における樹脂の溶融温度Tmは200~300℃程度としうる。
The molten resin extruded from the extruder 12 is filtered with a filter 28 or the like as necessary, and further mixed with a static mixer 30 or the like, and extruded from the die 14 into a film. The melting temperature Tm of the resin at the exit portion of the die 14 can be about 200 to 300.degree.
3)冷却固化工程
ダイから押し出された樹脂を、冷却ロール16と弾性タッチロール32とでニップして、フィルム状の溶融樹脂を所定の厚みにする。そして、フィルム状の溶融樹脂を、複数の冷却ロール18および20で段階的に冷却して固化させる。 3) Cooling and solidifying step The resin extruded from the die is nipped between the coolingroll 16 and the elastic touch roll 32 so that the film-like molten resin has a predetermined thickness. Then, the film-like molten resin is cooled stepwise with a plurality of cooling rolls 18 and 20 and solidified.
ダイから押し出された樹脂を、冷却ロール16と弾性タッチロール32とでニップして、フィルム状の溶融樹脂を所定の厚みにする。そして、フィルム状の溶融樹脂を、複数の冷却ロール18および20で段階的に冷却して固化させる。 3) Cooling and solidifying step The resin extruded from the die is nipped between the cooling
第1冷却ロール16の表面温度Tr1と第2冷却ロール18の表面温度Tr2は、それぞれ独立に(Tg-50)℃以上Tg以下としうる。また、Tr2>Tr1であることが好ましく、0<Tr2-Tr1<50であることがより好ましい。Tr2>Tr1とすることで、第2冷却ロール18上への添加剤の凝結が抑制され、フィルム中に再溶融されやすいからである。
The surface temperature Tr1 of the first cooling roll 16 and the surface temperature Tr2 of the second cooling roll 18 can be independently set to (Tg-50) ° C. or more and Tg or less. Further, Tr2> Tr1 is preferable, and 0 <Tr2-Tr1 <50 is more preferable. This is because by setting Tr2> Tr1, the condensation of the additive on the second cooling roll 18 is suppressed and the film is easily remelted.
添加剤のフィルム中への再溶解は、フィルムと第2冷却ロール18との接触時間によって調整でき、具体的には1.0~3.0秒であることが好ましい。接触時間は、第2冷却ロール18の周面の、フィルムと第2冷却ロール18とが接触し始める点と剥離し始める点との間の距離を、フィルムの搬送速度で除して得られる秒数である。
The re-dissolution of the additive into the film can be adjusted by the contact time between the film and the second cooling roll 18, and specifically, it is preferably 1.0 to 3.0 seconds. The contact time is a second obtained by dividing the distance between the point where the film and the second cooling roll 18 start to contact and the point where the second cooling roll 18 starts to peel by the film conveyance speed. Is a number.
第2冷却ロール18の周速度R2は、第1冷却ロール16の周速度R1よりも大きいことが好ましい。これらの2つの冷却ロール間のフィルムに張力が加わり、それによりフィルムと第1冷却ロール16との密着性が高められる。この周速度の比は1.00~1.05の範囲であることが好ましい。周速度の比が1.05超であると、フィルムが破断するおそれがある。同様に、第3冷却ロール20の周速度が、第2冷却ロール18の周速度よりも大きいことが好ましい。
The peripheral speed R2 of the second cooling roll 18 is preferably larger than the peripheral speed R1 of the first cooling roll 16. Tension is applied to the film between these two cooling rolls, thereby improving the adhesion between the film and the first cooling roll 16. The ratio of the peripheral speeds is preferably in the range of 1.00 to 1.05. If the ratio of the peripheral speeds exceeds 1.05, the film may be broken. Similarly, the peripheral speed of the third cooling roll 20 is preferably larger than the peripheral speed of the second cooling roll 18.
ドロー比は5~30であることが好ましい。ドロー比は、ダイ14のリップクリアランスを、第1、第2および第3冷却ロール16、18および20上で冷却固化して得られるフィルムの平均膜厚で除して得られる値である。ドロー比を上記範囲とすることで、液晶表示装置で画像を表示したときに、明暗のスジや斑点状ムラとなる故障が少ないフィルムが得られやすい。ドロー比は、ダイリップクリアランスと冷却ロールの引き取り速度により調整できる。
The draw ratio is preferably 5-30. The draw ratio is a value obtained by dividing the lip clearance of the die 14 by the average film thickness of the film obtained by cooling and solidifying on the first, second and third cooling rolls 16, 18 and 20. By setting the draw ratio within the above range, it is easy to obtain a film with few failures that cause bright and dark stripes and spotted unevenness when an image is displayed on a liquid crystal display device. The draw ratio can be adjusted by the die lip clearance and the take-up speed of the cooling roll.
ダイ14のリップ(開口部)から第1冷却ロール16の表面への溶融樹脂の吐出は、好ましくは70kPa以下、より好ましくは50~70kPaに減圧下で行うことが好ましい。得られるフィルムにダイラインが生じにくいからである。ダイ14のリップ(開口部)と第1冷却ロール16の表面との間を減圧する方法は、例えばダイ14と第1冷却ロール16とを含む空間を耐圧部材で覆い、かつその内部を減圧する方法などがある。
The discharge of the molten resin from the lip (opening) of the die 14 to the surface of the first cooling roll 16 is preferably performed at a reduced pressure of 70 kPa or less, more preferably 50 to 70 kPa. This is because die lines are less likely to occur in the obtained film. The method of reducing the pressure between the lip (opening) of the die 14 and the surface of the first cooling roll 16 is, for example, covering the space including the die 14 and the first cooling roll 16 with a pressure-resistant member and reducing the pressure inside the space. There are methods.
弾性タッチロール32の表面温度Tr0は、フィルムのガラス転移温度(Tg)以下であることが好ましく、Tg-50≦Tr0≦Tgであることがより好ましい。弾性タッチロール32の表面温度Tr0がTg超であると、フィルムと第1冷却ロール16とが剥離しにくくなることがある。
The surface temperature Tr0 of the elastic touch roll 32 is preferably equal to or lower than the glass transition temperature (Tg) of the film, and more preferably Tg-50 ≦ Tr0 ≦ Tg. If the surface temperature Tr0 of the elastic touch roll 32 exceeds Tg, the film and the first cooling roll 16 may be difficult to peel off.
弾性タッチロール32で押圧する時の、弾性タッチロール32の線圧を9.8~147N/cmにすることが好ましい。線圧が9.8N/cm未満であると、ダイラインを十分に抑制しにくい。
It is preferable that the linear pressure of the elastic touch roll 32 when pressed by the elastic touch roll 32 is 9.8 to 147 N / cm. When the linear pressure is less than 9.8 N / cm, it is difficult to sufficiently suppress the die line.
光学フィルムのガラス転移温度をTgとしたとき、ダイ14から押し出されたフィルム状の溶融樹脂の、弾性タッチロール32でニップされる直前の弾性タッチロール32側の表面温度Ttは、好ましくはTg<Tt<Tg+110℃であり、より好ましくはTg+10℃<Tt<Tg+90℃であり、さらに好ましくはTg+20℃<Tt<Tg+70℃である。フィルム状の溶融樹脂の表面温度Ttが上記範囲であると、ニップするときのフィルム状の溶融樹脂の粘度を、適切な範囲にすることができ、ダイラインを抑制しやすい。
When the glass transition temperature of the optical film is Tg, the surface temperature Tt of the film-like molten resin extruded from the die 14 immediately before being nipped by the elastic touch roll 32 is preferably Tg < Tt <Tg + 110 ° C., more preferably Tg + 10 ° C. <Tt <Tg + 90 ° C., and further preferably Tg + 20 ° C. <Tt <Tg + 70 ° C. When the surface temperature Tt of the film-like molten resin is in the above range, the viscosity of the film-like molten resin when nipping can be set to an appropriate range, and die lines can be easily suppressed.
フィルム状の溶融樹脂の、弾性タッチロール32にニップされる直前の弾性タッチロール32側の表面温度Ttの調整は、例えばダイ14と第1冷却ロール16との間のエアギャップ(距離)を短くして、ダイ14と第1冷却ロール16との間での冷却を抑制する方法、ダイ14と第1冷却ロール16との間を断熱材で囲って保温または加温する方法などによって行うことができる。加温は、熱風、赤外線ヒーターまたはマイクロ波による加熱などでありうる。
The adjustment of the surface temperature Tt on the elastic touch roll 32 immediately before being nipped by the elastic touch roll 32 of the film-like molten resin, for example, shortens the air gap (distance) between the die 14 and the first cooling roll 16. Then, the method of suppressing the cooling between the die 14 and the first cooling roll 16, the method of keeping the temperature between the die 14 and the first cooling roll 16 with a heat insulating material or the method of heating or the like. it can. The heating can be heating with hot air, an infrared heater or microwave.
フィルムの表面温度やロールの表面温度は、非接触式の赤外温度計で測定できる。具体的には、フィルムまたはロールの表面温度は、非接触ハンディ温度計(IT2-80、(株)キーエンス製)を用いて、フィルムまたはロールの幅方向の任意の10箇所の表面温度を、フィルムまたはロールの表面から0.5m離れた位置で測定する。
The film surface temperature and roll surface temperature can be measured with a non-contact infrared thermometer. Specifically, the surface temperature of the film or roll is determined by using a non-contact handy thermometer (IT2-80, manufactured by Keyence Co., Ltd.), the surface temperature at any 10 locations in the width direction of the film or roll, Or it measures at the position 0.5m away from the surface of the roll.
冷却ロール16、18および20で固化させたフィルムを、剥離ロール22で剥離する。フィルムを剥離する際は、変形を防止するために、フィルムに加える張力を調整することが好ましい。
The film solidified by the cooling rolls 16, 18 and 20 is peeled off by the peeling roll 22. When peeling the film, it is preferable to adjust the tension applied to the film in order to prevent deformation.
4)延伸工程
得られたフィルムを、延伸装置24にて延伸して光学フィルムを得る。延伸は、フィルムの幅方向(TD方向)、搬送方向(MD方向)または斜め方向のうち少なくとも一方向に延伸すればよく、フィルムの幅方向(TD方向)と搬送方向(MD方向)の両方に延伸することが好ましい。 4) Stretching step The obtained film is stretched by a stretchingdevice 24 to obtain an optical film. The stretching may be performed in at least one of the width direction of the film (TD direction), the transport direction (MD direction), or the oblique direction, and both in the film width direction (TD direction) and the transport direction (MD direction). It is preferable to stretch.
得られたフィルムを、延伸装置24にて延伸して光学フィルムを得る。延伸は、フィルムの幅方向(TD方向)、搬送方向(MD方向)または斜め方向のうち少なくとも一方向に延伸すればよく、フィルムの幅方向(TD方向)と搬送方向(MD方向)の両方に延伸することが好ましい。 4) Stretching step The obtained film is stretched by a stretching
フィルムの幅方向(TD方向)と搬送方向(MD方向)の両方に延伸する場合、フィルムの幅方向(TD方向)の延伸と搬送方向(MD方向)の延伸とは、逐次的に行ってもよいし、同時に行ってもよい。
When stretching in both the width direction (TD direction) and the transport direction (MD direction) of the film, stretching in the width direction (TD direction) of the film and stretching in the transport direction (MD direction) may be performed sequentially. You may do it simultaneously.
延伸倍率は、各方向に1.01~3.0倍、好ましくは1.1~2.0倍としうる。フィルムの幅方向(TD方向)と搬送方向(MD方向)の両方に延伸する場合、各方向に最終的に1.01~3.0倍、好ましくは1.1~2.0倍とすることが好ましい。
The draw ratio may be 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction. When the film is stretched in both the width direction (TD direction) and the conveyance direction (MD direction), it is finally 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction. Is preferred.
延伸温度は、Tg~(Tg+50)℃であることが好ましく、Tg~(Tg+40)℃であることがより好ましい。具体的には、(メタ)アクリル樹脂/セルロースエステルの混合物の場合、延伸温度は、100~190℃程度としうる。延伸温度が高すぎると、得られる光学フィルムの引き裂き強度は高いが、破断応力が低いことがある。一方、延伸温度が低すぎると、得られる光学フィルムは、破断応力は高いが、引き裂き強度が低いことがある。
The stretching temperature is preferably Tg to (Tg + 50) ° C., more preferably Tg to (Tg + 40) ° C. Specifically, in the case of a (meth) acrylic resin / cellulose ester mixture, the stretching temperature can be about 100 to 190 ° C. When the stretching temperature is too high, the tear strength of the obtained optical film is high, but the breaking stress may be low. On the other hand, when the stretching temperature is too low, the obtained optical film has a high breaking stress but may have a low tear strength.
延伸温度は、フィルムの幅方向(TD方向)または搬送方向(MD方向)に均一であることが好ましく、フィルムの延伸温度の幅方向または搬送方向のばらつきが±2℃以下であることが好ましく、±1℃以下であることがより好ましく、±0.5℃以下であることがさらに好ましい。
The stretching temperature is preferably uniform in the width direction (TD direction) or the transport direction (MD direction) of the film, and the variation in the width direction or transport direction of the film stretching temperature is preferably ± 2 ° C. or less, The temperature is more preferably ± 1 ° C. or less, and further preferably ± 0.5 ° C. or less.
延伸後に得られるフィルムのレターデーションを調整したり、寸法変化を少なくしたりするために、必要に応じて、延伸後に得られるフィルムを搬送方向(MD方向)または幅方向(TD方向)に収縮させてもよい。延伸後に得られるフィルムを搬送方向(MD方向)に収縮させるには、例えば幅方向に把持したクリップを解除して、搬送方向に弛緩させたり;隣り合うクリップの間隔を搬送方向に徐々に狭くして搬送方向に弛緩させたりすればよい。
In order to adjust the retardation of the film obtained after stretching or to reduce the dimensional change, the film obtained after stretching is shrunk in the transport direction (MD direction) or the width direction (TD direction) as necessary. May be. To shrink the film obtained after stretching in the transport direction (MD direction), for example, release the clip gripped in the width direction and loosen it in the transport direction; gradually reduce the interval between adjacent clips in the transport direction. To relax in the transport direction.
隣り合うクリップの間隔を搬送方向に徐々に狭くするには、例えば同時二軸延伸機を用いて、フィルムの搬送方向(TD方向)の隣り合うクリップの間隔を、パンタグラフ方式やリニアドライブ方式で駆動して滑らかに徐々に狭くするとよい。得られるフィルムの寸法変化率を小さくするためには、フィルムの幅方向(TD方向)と搬送方向(MD方向)ともに0.5~10%収縮させることが好ましい。
To gradually reduce the distance between adjacent clips in the transport direction, for example, using a simultaneous biaxial stretching machine, the distance between adjacent clips in the film transport direction (TD direction) is driven by the pantograph method or linear drive method. Then it should be smooth and narrow. In order to reduce the dimensional change rate of the film to be obtained, it is preferable to shrink the film in the width direction (TD direction) and the transport direction (MD direction) by 0.5 to 10%.
得られる光学フィルムの幅は、偏光子の幅などにもよるが、0.5~4.0m、好ましくは1.0~3.0mとしうる。光学フィルムの膜厚変動は、±3%以下であることが好ましく、±1%以下であることがさらに好ましい。
The width of the obtained optical film may be 0.5 to 4.0 m, preferably 1.0 to 3.0 m, although it depends on the width of the polarizer. The film thickness variation of the optical film is preferably ± 3% or less, and more preferably ± 1% or less.
延伸後、得られる光学フィルムの両端部をスリットして裁ち落とした後、ナール加工(エンボッシング加工)を施すことが好ましい。得られる光学フィルム同士の貼り付きやすり傷の発生を防止するためである。ナール加工は、エンボスリングとバックロールとを有するナール加工装置で行うことができる。このようにして得られる光学フィルムを、巻取り機によって巻き取る。
After stretching, it is preferable to apply knurl processing (embossing processing) after slitting and cutting off both ends of the obtained optical film. This is for preventing the occurrence of sticking or scratching between the obtained optical films. The knurling can be performed with a knurling apparatus having an embossing ring and a back roll. The optical film thus obtained is wound up by a winder.
このように、本発明の光学フィルムは、(メタ)アクリル樹脂と酸トラップ剤とを含有する樹脂組成物を溶融混練した後、押し出すステップを経て得ることができる。この樹脂組成物に含まれる酸トラップ剤は、溶融温度を高くしたときに、(メタ)アクリル樹脂に残留するモノマーが熱分解して生成する酸やセルロースエステルのエステル部が加水分解して生成する酸をトラップしうるため、樹脂の熱劣化を抑制できる。そのため、着色がなく、所望の光学特性を満たし、かつ柔軟性が高く、リワーク性の高い光学フィルムを得ることができる。
Thus, the optical film of the present invention can be obtained through a step of extruding after melt-kneading a resin composition containing a (meth) acrylic resin and an acid trapping agent. The acid trapping agent contained in this resin composition is produced when the monomer remaining in the (meth) acrylic resin is thermally decomposed and the ester part of cellulose ester is hydrolyzed when the melting temperature is increased. Since the acid can be trapped, the thermal deterioration of the resin can be suppressed. Therefore, it is possible to obtain an optical film that is not colored, satisfies desired optical characteristics, has high flexibility, and has high reworkability.
3.偏光板
本発明の偏光板は、偏光子と、その少なくとも一方の面に配置された本発明の光学フィルムとを含む。 3. Polarizing plate The polarizing plate of the present invention comprises a polarizer and the optical film of the present invention disposed on at least one surface thereof.
本発明の偏光板は、偏光子と、その少なくとも一方の面に配置された本発明の光学フィルムとを含む。 3. Polarizing plate The polarizing plate of the present invention comprises a polarizer and the optical film of the present invention disposed on at least one surface thereof.
偏光子は、一定方向の偏波面の光のみを通過させる素子である。偏光子の代表的な例は、ポリビニルアルコール系偏光フィルムであり、ポリビニルアルコール系フィルムにヨウ素を染色させたものと、二色性染料を染色させたものと、がある。
A polarizer is an element that allows only light of a polarization plane in a certain direction to pass through. A typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.
偏光子は、ポリビニルアルコール系フィルムを一軸延伸した後、ヨウ素または二色性染料で染色して得られるフィルムであってもよいし、ポリビニルアルコール系フィルムをヨウ素または二色性染料で染色した後、一軸延伸したフィルム(好ましくはさらにホウ素化合物で耐久性処理を施したフィルム)であってもよい。偏光子の厚さは、5~30μmであることが好ましく、10~20μmであることがより好ましい。
The polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing with iodine or a dichroic dye, or after dyeing a polyvinyl alcohol film with iodine or a dichroic dye, A uniaxially stretched film (preferably a film further subjected to durability treatment with a boron compound) may be used. The thickness of the polarizer is preferably 5 to 30 μm, more preferably 10 to 20 μm.
ポリビニルアルコール系フィルムは、ポリビニルアルコール水溶液を製膜したものであってもよい。ポリビニルアルコール系フィルムは、偏光性能および耐久性能に優れ、色斑が少ないなどことから、エチレン変性ポリビニルアルコールフィルムが好ましい。エチレン変性ポリビニルアルコールフィルムの例には、特開2003-248123号、特開2003-342322号等に記載されたエチレン単位の含有量1~4モル%、重合度2000~4000、けん化度99.0~99.99モル%のフィルムが含まれる。
The polyvinyl alcohol film may be a film formed from a polyvinyl alcohol aqueous solution. The polyvinyl alcohol film is preferably an ethylene-modified polyvinyl alcohol film because it is excellent in polarizing performance and durability performance and has few color spots. Examples of the ethylene-modified polyvinyl alcohol film include an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000, and a degree of saponification of 99.0, as described in JP-A Nos. 2003-248123 and 2003-342322. ˜99.99 mol% film is included.
二色性色素の例には、アゾ系色素、スチルベン系色素、ピラゾロン系色素、トリフェニルメタン系色素、キノリン系色素、オキサジン系色素、チアジン系色素およびアントラキノン系色素などが含まれる。
Examples of dichroic dyes include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.
本発明の光学フィルムは、偏光子の少なくとも一方の面に直接配置されてもよいし、他のフィルムまたは層を介して配置されてもよい。
The optical film of the present invention may be disposed directly on at least one surface of the polarizer, or may be disposed via another film or layer.
偏光子の他方の面には、本発明の光学フィルムが配置されてもよいし、それ以外の保護フィルムが配置されてもよい。保護フィルムは、特に制限されず、通常のセルロースエステルフィルムなどであってよい。セルロースエステルフィルムの市販品の例には、市販のセルロースエステルフィルム(例えば、コニカミノルタタック KC8UX、KC4UX、KC5UX、KC8UY、KC4UY、KC12UR、KC8UCR-3、KC8UCR-4、KC8UCR-5、KC8UE、KC4UE、KC4FR-3、KC4FR-4、KC4HR-1、KC8UY-HA、KC8UX-RHA、以上コニカミノルタオプト(株)製)等が好ましく用いられる。
The optical film of the present invention may be disposed on the other surface of the polarizer, or a protective film other than that may be disposed. The protective film is not particularly limited, and may be a normal cellulose ester film or the like. Examples of commercially available cellulose ester films include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4UE, KC4FR-3, KC4FR-4, KC4HR-1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.
偏光板は、通常、偏光子と、本発明の光学フィルムとを貼り合わせるステップを経て得ることができる。貼り合わせに用いられる接着剤の例には、完全鹸化型ポリビニルアルコール水溶液や;ウレタン系粘着剤、エポキシ系粘着剤、水性高分子-イソシアネート系粘着剤、熱硬化型アクリル粘着剤などの硬化型粘着剤が含まれ、好ましくは完全鹸化型ポリビニルアルコール水溶液である。
The polarizing plate can be usually obtained through a step of bonding a polarizer and the optical film of the present invention. Examples of adhesives used for pasting include saponified polyvinyl alcohol aqueous solutions, curable adhesives such as urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, thermosetting acrylic adhesives, etc. A fully saponified polyvinyl alcohol aqueous solution is preferable.
4.液晶表示装置
本発明の液晶表示装置は、液晶セルと、それを挟持する一対の偏光板と、を有する。そして、一対の偏光板のうち少なくとも一方が本発明の光学フィルムを有する偏光板であり、好ましくは一対の偏光板の両方が本発明の光学フィルムを有する偏光板である。 4). Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one is a polarizing plate which has an optical film of this invention among a pair of polarizing plates, Preferably both of a pair of polarizing plates are polarizing plates which have an optical film of this invention.
本発明の液晶表示装置は、液晶セルと、それを挟持する一対の偏光板と、を有する。そして、一対の偏光板のうち少なくとも一方が本発明の光学フィルムを有する偏光板であり、好ましくは一対の偏光板の両方が本発明の光学フィルムを有する偏光板である。 4). Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one is a polarizing plate which has an optical film of this invention among a pair of polarizing plates, Preferably both of a pair of polarizing plates are polarizing plates which have an optical film of this invention.
図2は、本発明に係る液晶表示装置110の一実施形態の基本構成を示す模式図である。図2に示されるように、液晶表示装置110は、液晶セル120と、それを挟持する第一の偏光板140および第二の偏光板160と、バックライト180と、を有する。
FIG. 2 is a schematic diagram showing a basic configuration of an embodiment of the liquid crystal display device 110 according to the present invention. As shown in FIG. 2, the liquid crystal display device 110 includes a liquid crystal cell 120, a first polarizing plate 140 and a second polarizing plate 160 that sandwich the liquid crystal cell 120, and a backlight 180.
液晶セル120の表示方式は、特に制限されず、TN(Twisted Nematic)方式、STN(Super Twisted Nematic)方式、IPS(In-Plane Switching)方式(FFS方式も含む)、OCB(Optically Compensated Birefringence)方式、VA(Vertical Alignment)方式(MVA;Multi-domain Vertical AlignmentやPVA;Patterned Vertical Alignmentも含む)、HAN(Hybrid Aligned Nematic)方式等がある。視野角が比較的広いなどの観点からは、IPS方式などが好ましく、コントラストが高いなどの観点からは、VA方式などが好ましい。
The display method of the liquid crystal cell 120 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an IPS (In-Plane Switching) method (including an FFS method), an OCB (OpticallyalCompensating Bensing method). VA (Vertical Alignment) method (MVA; including Multi-domain Vertical Alignment and PVA; Patterned Vertical Alignment also included), HAN (Hybrid Aligned Nematic) method, and the like. From the viewpoint of a relatively wide viewing angle, the IPS system is preferable, and from the viewpoint of high contrast, the VA system is preferable.
第一の偏光板140は、液晶セル120の視認側に配置されており、第一の偏光子142と、第一の偏光子142の視認側の面に配置された保護フィルム144(F1)と、第一の偏光子142の液晶セル側の面に配置された保護フィルム146(F2)とを含む。第二の偏光板160は、バックライト180側に配置されており、第二の偏光子162と、第二の偏光子162の液晶セル側の面に配置された保護フィルム164(F3)と、第二の偏光子162のバックライト側の面に配置された保護フィルム166(F4)とを含む。保護フィルム146(F2)と164(F3)の一方は、必要に応じて省略されてもよい。
The first polarizing plate 140 is disposed on the viewing side of the liquid crystal cell 120, and the first polarizer 142 and the protective film 144 (F1) disposed on the viewing side of the first polarizer 142. And a protective film 146 (F2) disposed on the surface of the first polarizer 142 on the liquid crystal cell side. The second polarizing plate 160 is disposed on the backlight 180 side, the second polarizer 162, a protective film 164 (F3) disposed on the liquid crystal cell side surface of the second polarizer 162, And a protective film 166 (F4) disposed on the backlight side surface of the second polarizer 162. One of the protective films 146 (F2) and 164 (F3) may be omitted as necessary.
保護フィルム144(F1)、146(F2)、164(F3)および166(F4)のうち、液晶セル側に配置される保護フィルム146(F2)と164(F3)の少なくとも一方を、本発明の光学フィルムとすることが好ましい。
Of the protective films 144 (F1), 146 (F2), 164 (F3), and 166 (F4), at least one of the protective films 146 (F2) and 164 (F3) arranged on the liquid crystal cell side of the present invention is used. An optical film is preferred.
液晶表示装置の大きさは、好ましくは30型以上、より好ましくは30型~54型としうる。液晶表示装置は、好ましくはデジタルサイネージなどの屋外用途にも好ましく用いられる。
The size of the liquid crystal display device is preferably 30 or more, more preferably 30 to 54. The liquid crystal display device is preferably used also for outdoor applications such as digital signage.
液晶表示装置は、液晶セルと偏光板とを粘着剤を介して貼り合わせるステップを経て製造されうる。粘着剤は、硬化型粘着剤であることが好ましく、硬化物の25℃における貯蔵弾性率が1.0×104~1.0×109Paである硬化型粘着剤がより好ましい。そのような粘着剤の例には、前述の硬化型粘着剤と同様のものが含まれる。
The liquid crystal display device can be manufactured through a step of bonding a liquid crystal cell and a polarizing plate together with an adhesive. The pressure-sensitive adhesive is preferably a curable pressure-sensitive adhesive, and more preferably a curable pressure-sensitive adhesive having a cured elastic modulus at 25 ° C. of 1.0 × 10 4 to 1.0 × 10 9 Pa. Examples of such an adhesive include those similar to the above-mentioned curable adhesive.
前述のように、本発明の光学フィルムは、酸トラップ剤を含有する樹脂組成物を高い溶融温度で溶融混練するステップを経て得られる。そのため、本発明の光学フィルムは、着色などがなく、所望の光学特性を満たしつつ、高い柔軟性(リワーク性)を有する。そのため、本発明の光学フィルムを含む偏光板を、液晶セルに一旦貼り合わせた後でも、偏光板を裂けさせることなく、液晶セルから容易に剥がすことができる。また、本発明の光学フィルムを含む液晶表示装置は、良好な表示特性を有する。
As described above, the optical film of the present invention is obtained through a step of melt-kneading a resin composition containing an acid trapping agent at a high melting temperature. Therefore, the optical film of the present invention is not colored and has high flexibility (reworkability) while satisfying desired optical characteristics. Therefore, even after the polarizing plate including the optical film of the present invention is once bonded to the liquid crystal cell, it can be easily peeled off from the liquid crystal cell without tearing the polarizing plate. Moreover, the liquid crystal display device containing the optical film of this invention has a favorable display characteristic.
以下において、実施例を参照して本発明をより詳細に説明する。これらの実施例によって、本発明の範囲は限定して解釈されない。
Hereinafter, the present invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.
1.光学フィルム材料の準備
1)(メタ)アクリル樹脂
A1:メチルメタクリレート/アクリロイルモルホリン=85/15(質量比)の共重合体、重量平均分子量Mw=10万
A2:ラクトン環含有(メタ)アクリル共重合体(ラクトン環含有構造の含有割合:20質量%、閉環度95%、重量平均分子量Mw=20万)
A3:ラクトン環含有(メタ)アクリル共重合体(ラクトン環含有構造の含有割合:20質量%、閉環度80%、重量平均分子量Mw=20万)
2)セルロースエステル
CAP:セルロースアセテートプロピオネート(アシル基総置換度2.75、アセチル基置換度0.2、プロピオニル基置換度2.55、重量平均分子量Mw:200000、Tg:145℃)
3)酸トラップ剤
LBT-1830:堺化学工業社製、ステアリルリン酸亜鉛
アデカサイザーD-32:ADEKA社製、エポキシ化オイル
4)その他の添加剤
SZ-2000:堺化学工業社製、ステアリン酸亜鉛
PEP-36:ADEKA社製、リン系酸化防止剤
Irganox1010:チバ・ジャパン製、フェノール系酸化防止剤
アデカスタッブLA-52:ADEKA社製HALS
5)その他の樹脂
ポリカーボネート1:パンライト AD-5503(帝人化成(株)製)
アートン(環状オレフィン樹脂):アートン G7810(JSR(株)製) 1. Preparation of Optical Film Material 1) (Meth) acrylic resin A1: Copolymer of methyl methacrylate / acryloylmorpholine = 85/15 (mass ratio), weight average molecular weight Mw = 100,000 A2: Lactone ring-containing (meth) acrylic copolymer Union (content of lactone ring-containing structure: 20% by mass, degree of ring closure 95%, weight average molecular weight Mw = 200,000)
A3: Lactone ring-containing (meth) acrylic copolymer (Lactone ring-containing structure content ratio: 20% by mass, ring closure degree 80%, weight average molecular weight Mw = 200,000)
2) Cellulose ester CAP: cellulose acetate propionate (acyl group total substitution degree 2.75, acetyl group substitution degree 0.2, propionyl group substitution degree 2.55, weight average molecular weight Mw: 200000, Tg: 145 ° C.)
3) Acid trapping agent LBT-1830: manufactured by Sakai Chemical Industry Co., Ltd., zinc stearyl phosphate Adekasizer D-32: manufactured by ADEKA, epoxidized oil 4) Other additives SZ-2000: manufactured by Sakai Chemical Industry Co., Ltd., stearic acid Zinc PEP-36: Made by ADEKA, Phosphorous antioxidant Irganox 1010: Made by Ciba Japan, Phenolic antioxidant Adeka stub LA-52: HALS made by ADEKA
5) Other resins Polycarbonate 1: Panlite AD-5503 (manufactured by Teijin Chemicals Ltd.)
Arton (cyclic olefin resin): Arton G7810 (manufactured by JSR Corporation)
1)(メタ)アクリル樹脂
A1:メチルメタクリレート/アクリロイルモルホリン=85/15(質量比)の共重合体、重量平均分子量Mw=10万
A2:ラクトン環含有(メタ)アクリル共重合体(ラクトン環含有構造の含有割合:20質量%、閉環度95%、重量平均分子量Mw=20万)
A3:ラクトン環含有(メタ)アクリル共重合体(ラクトン環含有構造の含有割合:20質量%、閉環度80%、重量平均分子量Mw=20万)
2)セルロースエステル
CAP:セルロースアセテートプロピオネート(アシル基総置換度2.75、アセチル基置換度0.2、プロピオニル基置換度2.55、重量平均分子量Mw:200000、Tg:145℃)
3)酸トラップ剤
LBT-1830:堺化学工業社製、ステアリルリン酸亜鉛
アデカサイザーD-32:ADEKA社製、エポキシ化オイル
4)その他の添加剤
SZ-2000:堺化学工業社製、ステアリン酸亜鉛
PEP-36:ADEKA社製、リン系酸化防止剤
Irganox1010:チバ・ジャパン製、フェノール系酸化防止剤
アデカスタッブLA-52:ADEKA社製HALS
5)その他の樹脂
ポリカーボネート1:パンライト AD-5503(帝人化成(株)製)
アートン(環状オレフィン樹脂):アートン G7810(JSR(株)製) 1. Preparation of Optical Film Material 1) (Meth) acrylic resin A1: Copolymer of methyl methacrylate / acryloylmorpholine = 85/15 (mass ratio), weight average molecular weight Mw = 100,000 A2: Lactone ring-containing (meth) acrylic copolymer Union (content of lactone ring-containing structure: 20% by mass, degree of ring closure 95%, weight average molecular weight Mw = 200,000)
A3: Lactone ring-containing (meth) acrylic copolymer (Lactone ring-containing structure content ratio: 20% by mass, ring closure degree 80%, weight average molecular weight Mw = 200,000)
2) Cellulose ester CAP: cellulose acetate propionate (acyl group total substitution degree 2.75, acetyl group substitution degree 0.2, propionyl group substitution degree 2.55, weight average molecular weight Mw: 200000, Tg: 145 ° C.)
3) Acid trapping agent LBT-1830: manufactured by Sakai Chemical Industry Co., Ltd., zinc stearyl phosphate Adekasizer D-32: manufactured by ADEKA, epoxidized oil 4) Other additives SZ-2000: manufactured by Sakai Chemical Industry Co., Ltd., stearic acid Zinc PEP-36: Made by ADEKA, Phosphorous antioxidant Irganox 1010: Made by Ciba Japan, Phenolic antioxidant Adeka stub LA-52: HALS made by ADEKA
5) Other resins Polycarbonate 1: Panlite AD-5503 (manufactured by Teijin Chemicals Ltd.)
Arton (cyclic olefin resin): Arton G7810 (manufactured by JSR Corporation)
2.光学フィルムの作製
(実施例1)
(メタ)アクリル樹脂A1と、セルロースアセテートプロピオネートとを、真空ナウターミキサーにて70℃、減圧下で3時間乾燥させた後、室温まで冷却した。これに、LBT-1830を添加して、混合物を得た。混合物の組成は、得られる光学フィルムの組成が以下の組成となるようにした。
<光学フィルムの組成>
(メタ)アクリル樹脂A1:70質量部
セルロースアセテートプロピオネート(アシル基総置換度2.75、アセチル基置換度0.2、プロピオニル基置換度2.55、分子量Mw=200000):30質量部
LBT-1830:2質量部 2. Production of optical film (Example 1)
(Meth) acrylic resin A1 and cellulose acetate propionate were dried in a vacuum nauter mixer at 70 ° C. under reduced pressure for 3 hours, and then cooled to room temperature. To this, LBT-1830 was added to obtain a mixture. The composition of the mixture was such that the resulting optical film had the following composition.
<Composition of optical film>
(Meth) acrylic resin A1: 70 parts by mass Cellulose acetate propionate (acyl group total substitution degree 2.75, acetyl group substitution degree 0.2, propionyl group substitution degree 2.55, molecular weight Mw = 200000): 30 parts by mass LBT-1830: 2 parts by mass
(実施例1)
(メタ)アクリル樹脂A1と、セルロースアセテートプロピオネートとを、真空ナウターミキサーにて70℃、減圧下で3時間乾燥させた後、室温まで冷却した。これに、LBT-1830を添加して、混合物を得た。混合物の組成は、得られる光学フィルムの組成が以下の組成となるようにした。
<光学フィルムの組成>
(メタ)アクリル樹脂A1:70質量部
セルロースアセテートプロピオネート(アシル基総置換度2.75、アセチル基置換度0.2、プロピオニル基置換度2.55、分子量Mw=200000):30質量部
LBT-1830:2質量部 2. Production of optical film (Example 1)
(Meth) acrylic resin A1 and cellulose acetate propionate were dried in a vacuum nauter mixer at 70 ° C. under reduced pressure for 3 hours, and then cooled to room temperature. To this, LBT-1830 was added to obtain a mixture. The composition of the mixture was such that the resulting optical film had the following composition.
<Composition of optical film>
(Meth) acrylic resin A1: 70 parts by mass Cellulose acetate propionate (acyl group total substitution degree 2.75, acetyl group substitution degree 0.2, propionyl group substitution degree 2.55, molecular weight Mw = 200000): 30 parts by mass LBT-1830: 2 parts by mass
得られた混合物を、2軸式押し出し機にて235℃で溶融混練して、ストランド状に押し出した。ストランド状に押し出された樹脂組成物を水冷した後、カッティングしてペレットを得た。
The obtained mixture was melt-kneaded at 235 ° C. with a twin-screw extruder and extruded into a strand shape. The resin composition extruded in a strand form was cooled with water and then cut to obtain pellets.
得られたペレットを用いて、図1に示されるフィルムの製造装置10にて、光学フィルムを製造した。得られたペレットを1軸押し出し機(押し出し機12)に投入し、窒素雰囲気下、260℃で溶融混練した。その後、ダイ14から、表面温度が90℃である第1冷却ロール16上に押し出した。そして、第1冷却ロール16上に押し出された樹脂を、弾性タッチロール32で押圧して成形した。
Using the obtained pellets, an optical film was produced with the film production apparatus 10 shown in FIG. The obtained pellets were put into a single screw extruder (extruder 12), and melt kneaded at 260 ° C. in a nitrogen atmosphere. Then, it extruded from the die | dye 14 on the 1st cooling roll 16 whose surface temperature is 90 degreeC. Then, the resin extruded onto the first cooling roll 16 was pressed by the elastic touch roll 32 and molded.
ダイ14のスリットのギャップが、フィルム幅方向の端部から30mm以内では0.5mm、それ以外の箇所では1mmとした。弾性タッチロール32の表面温度は80℃とした。
The slit gap of the die 14 was 0.5 mm within 30 mm from the end in the film width direction, and 1 mm at other locations. The surface temperature of the elastic touch roll 32 was 80 ° C.
ダイ14から押し出された樹脂が第1冷却ロール16に接触する位置P1から、第1冷却ロール16と弾性タッチロール32とのニップ部分の、第1冷却ロール16の回転方向上流端の位置P2までの、第1冷却ローラ16の周面に沿った長さLを20mmとした。弾性タッチロール32の第1冷却ロール16に対する線圧は14.7N/cmとした。
From a position P1 at which the resin extruded from the die 14 contacts the first cooling roll 16 to a position P2 at the upstream end of the first cooling roll 16 in the nip portion between the first cooling roll 16 and the elastic touch roll 32 The length L along the peripheral surface of the first cooling roller 16 was set to 20 mm. The linear pressure of the elastic touch roll 32 against the first cooling roll 16 was 14.7 N / cm.
ダイ14から押し出された樹脂を、第1、第2および第3冷却ロール上で冷却固化して得られたフィルムを、剥離ロール22で剥離した。得られたフィルムを、テンター延伸機にて幅方向に145℃で1.3倍延伸した後、幅方向に3%緩和させながら30℃まで冷却した。次いで、クリップを外して、フィルム両端部のクリップで把持されていた部分を裁ち落とした後、フィルム両端部に幅10mm、高さ5μmのナーリング加工を施した。得られたフィルムを、巻き取り張力220N/mにて巻き取った。得られたフィルムは、膜厚40μm、幅1430mmであり、DSC法により測定されるガラス転移温度は125℃であった。
The film obtained by cooling and solidifying the resin extruded from the die 14 on the first, second and third cooling rolls was peeled off by the peeling roll 22. The obtained film was stretched 1.3 times at 145 ° C. in the width direction by a tenter stretching machine, and then cooled to 30 ° C. while relaxing 3% in the width direction. Next, the clip was removed, and the portions held by the clips at both ends of the film were cut off, and then knurling with a width of 10 mm and a height of 5 μm was applied to both ends of the film. The obtained film was wound up at a winding tension of 220 N / m. The obtained film had a thickness of 40 μm and a width of 1430 mm, and the glass transition temperature measured by the DSC method was 125 ° C.
(実施例2~4)
酸トラップ剤の種類または溶融温度を表1に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Examples 2 to 4)
An optical film was obtained in the same manner as in Example 1 except that the type of the acid trapping agent or the melting temperature was changed as shown in Table 1.
酸トラップ剤の種類または溶融温度を表1に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Examples 2 to 4)
An optical film was obtained in the same manner as in Example 1 except that the type of the acid trapping agent or the melting temperature was changed as shown in Table 1.
(実施例5~8)
酸トラップ剤の含有量を表1に示されるように変更した以外は実施例4と同様にして光学フィルムを得た。 (Examples 5 to 8)
An optical film was obtained in the same manner as in Example 4 except that the content of the acid trapping agent was changed as shown in Table 1.
酸トラップ剤の含有量を表1に示されるように変更した以外は実施例4と同様にして光学フィルムを得た。 (Examples 5 to 8)
An optical film was obtained in the same manner as in Example 4 except that the content of the acid trapping agent was changed as shown in Table 1.
(実施例9~12)
(A)(メタ)アクリル樹脂と(B)セルロースエステルとの含有比率A/Bを表1に示されるように変更した以外は実施例3と同様にして光学フィルムを得た。 (Examples 9 to 12)
An optical film was obtained in the same manner as in Example 3 except that the content ratio A / B of (A) (meth) acrylic resin and (B) cellulose ester was changed as shown in Table 1.
(A)(メタ)アクリル樹脂と(B)セルロースエステルとの含有比率A/Bを表1に示されるように変更した以外は実施例3と同様にして光学フィルムを得た。 (Examples 9 to 12)
An optical film was obtained in the same manner as in Example 3 except that the content ratio A / B of (A) (meth) acrylic resin and (B) cellulose ester was changed as shown in Table 1.
(実施例13および14)
(A)(メタ)アクリル樹脂の種類を表1に示されるように変更した以外は実施例3と同様にして光学フィルムを得た。 (Examples 13 and 14)
(A) An optical film was obtained in the same manner as in Example 3 except that the type of (meth) acrylic resin was changed as shown in Table 1.
(A)(メタ)アクリル樹脂の種類を表1に示されるように変更した以外は実施例3と同様にして光学フィルムを得た。 (Examples 13 and 14)
(A) An optical film was obtained in the same manner as in Example 3 except that the type of (meth) acrylic resin was changed as shown in Table 1.
(実施例15および16)
フィルムの膜厚を表3に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Examples 15 and 16)
An optical film was obtained in the same manner as in Example 1 except that the film thickness was changed as shown in Table 3.
フィルムの膜厚を表3に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Examples 15 and 16)
An optical film was obtained in the same manner as in Example 1 except that the film thickness was changed as shown in Table 3.
(比較例1)
酸トラップ剤を含有させなかった以外は実施例1と同様にして光学フィルムを得た。 (Comparative Example 1)
An optical film was obtained in the same manner as in Example 1 except that no acid trapping agent was contained.
酸トラップ剤を含有させなかった以外は実施例1と同様にして光学フィルムを得た。 (Comparative Example 1)
An optical film was obtained in the same manner as in Example 1 except that no acid trapping agent was contained.
(比較例2~5)
酸トラップ剤を含有させず、かつ溶融温度または延伸温度を表2に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 2 to 5)
An optical film was obtained in the same manner as in Example 1 except that no acid trapping agent was contained and the melting temperature or stretching temperature was changed as shown in Table 2.
酸トラップ剤を含有させず、かつ溶融温度または延伸温度を表2に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 2 to 5)
An optical film was obtained in the same manner as in Example 1 except that no acid trapping agent was contained and the melting temperature or stretching temperature was changed as shown in Table 2.
(比較例6~9)
酸トラップ剤を表2に示される添加剤に変更し、かつそれらの含有量を変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 6-9)
An optical film was obtained in the same manner as in Example 1 except that the acid trapping agent was changed to the additive shown in Table 2 and the content thereof was changed.
酸トラップ剤を表2に示される添加剤に変更し、かつそれらの含有量を変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 6-9)
An optical film was obtained in the same manner as in Example 1 except that the acid trapping agent was changed to the additive shown in Table 2 and the content thereof was changed.
(比較例10~13)
酸トラップ剤を表2に示される添加剤に変更し、さらにそれらの含有量と溶融温度を表2に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 10 to 13)
An optical film was obtained in the same manner as in Example 1 except that the acid trapping agent was changed to the additive shown in Table 2 and the content and melting temperature thereof were changed as shown in Table 2.
酸トラップ剤を表2に示される添加剤に変更し、さらにそれらの含有量と溶融温度を表2に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 10 to 13)
An optical film was obtained in the same manner as in Example 1 except that the acid trapping agent was changed to the additive shown in Table 2 and the content and melting temperature thereof were changed as shown in Table 2.
(比較例14)
フィルムの膜厚を表3に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Example 14)
An optical film was obtained in the same manner as in Example 1 except that the film thickness was changed as shown in Table 3.
フィルムの膜厚を表3に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Example 14)
An optical film was obtained in the same manner as in Example 1 except that the film thickness was changed as shown in Table 3.
(比較例15~18)
樹脂の種類、酸トラップ剤の添加の有無、延伸温度およびフィルムの膜厚を表4に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 15 to 18)
An optical film was obtained in the same manner as in Example 1 except that the type of resin, the presence or absence of addition of an acid trapping agent, the stretching temperature, and the film thickness of the film were changed as shown in Table 4.
樹脂の種類、酸トラップ剤の添加の有無、延伸温度およびフィルムの膜厚を表4に示されるように変更した以外は実施例1と同様にして光学フィルムを得た。 (Comparative Examples 15 to 18)
An optical film was obtained in the same manner as in Example 1 except that the type of resin, the presence or absence of addition of an acid trapping agent, the stretching temperature, and the film thickness of the film were changed as shown in Table 4.
得られた光学フィルムの1)破断応力、2)引き裂き強度、3)着色、4)レターデーションRth、5)リワーク性、および6)偏光子の劣化を、以下の方法で測定した。いずれの測定も、23℃55%RHの雰囲気下で行った。光学フィルムは、予め23℃55%RHの雰囲気下で24時間保存したものを使用した。
1) Breaking stress, 2) Tear strength, 3) Coloring, 4) Retardation Rth, 5) Reworkability, and 6) Polarizer deterioration of the obtained optical film were measured by the following methods. All measurements were performed in an atmosphere of 23 ° C. and 55% RH. The optical film used was stored for 24 hours in an atmosphere of 23 ° C. and 55% RH in advance.
1)破断応力
得られたフィルムを10mm×150mmの大きさにカットし、試料片とした。この試料片を、引張り試験機(ストログラフ-R2(東洋精機製))にて、チャック間距離100mm、温度25℃、延伸速度10mm/分で引っ張った。破断が生じたときの応力を、破断応力とした。 1) Breaking stress The obtained film was cut into a size of 10 mm × 150 mm to obtain a sample piece. This sample piece was pulled with a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) at a distance between chucks of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min. The stress when the rupture occurred was defined as the rupture stress.
得られたフィルムを10mm×150mmの大きさにカットし、試料片とした。この試料片を、引張り試験機(ストログラフ-R2(東洋精機製))にて、チャック間距離100mm、温度25℃、延伸速度10mm/分で引っ張った。破断が生じたときの応力を、破断応力とした。 1) Breaking stress The obtained film was cut into a size of 10 mm × 150 mm to obtain a sample piece. This sample piece was pulled with a tensile tester (Strograph-R2 (manufactured by Toyo Seiki)) at a distance between chucks of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min. The stress when the rupture occurred was defined as the rupture stress.
2)引き裂き強度
得られたフィルムを65mm×50mmの大きさにカットし、試料片とした。この試料片のエレメンドルフ法による引き裂き荷重を、JIS K 7128-1991に準拠して、東洋精機(株)製の軽荷重引き裂き装置(TYPE D)にて測定した。 2) Tear strength The obtained film was cut into a size of 65 mm × 50 mm to obtain a sample piece. The tear load of this sample piece by the Elmendorf method was measured with a light load tear device (TYPE D) manufactured by Toyo Seiki Co., Ltd. according to JIS K 7128-1991.
得られたフィルムを65mm×50mmの大きさにカットし、試料片とした。この試料片のエレメンドルフ法による引き裂き荷重を、JIS K 7128-1991に準拠して、東洋精機(株)製の軽荷重引き裂き装置(TYPE D)にて測定した。 2) Tear strength The obtained film was cut into a size of 65 mm × 50 mm to obtain a sample piece. The tear load of this sample piece by the Elmendorf method was measured with a light load tear device (TYPE D) manufactured by Toyo Seiki Co., Ltd. according to JIS K 7128-1991.
3)着色
アルミパンに、細かく粉砕した光学フィルムを10mg入れて、TG/DTA6200(エスアイアイ・ナノテクノロジー(株)製)を用いて、N2フロー下、250℃で60分間加熱した。加熱後のアルミパン内の光学フィルムの着色状態を目視観察した。着色の評価は、以下の基準に基づいて行った。
○:ほとんど着色がない
△:薄く着色
×:褐色に着色 3)Coloring 10 mg of a finely pulverized optical film was put in an aluminum pan, and heated at 250 ° C. for 60 minutes under N 2 flow using TG / DTA6200 (manufactured by SII Nanotechnology). The colored state of the optical film in the aluminum pan after heating was visually observed. The evaluation of coloring was performed based on the following criteria.
○: Almost no color △: Lightly colored ×: Colored brown
アルミパンに、細かく粉砕した光学フィルムを10mg入れて、TG/DTA6200(エスアイアイ・ナノテクノロジー(株)製)を用いて、N2フロー下、250℃で60分間加熱した。加熱後のアルミパン内の光学フィルムの着色状態を目視観察した。着色の評価は、以下の基準に基づいて行った。
○:ほとんど着色がない
△:薄く着色
×:褐色に着色 3)
○: Almost no color △: Lightly colored ×: Colored brown
4)レターデーションRth
i)フィルムの平均屈折率を屈折計により測定した。
ii)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向からの波長590nmの光を入射させたときの面内方向のレターデーションR0を測定した。
iii)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向に対してθの角度(入射角(θ))から波長590nmの光を入射させたときのレターデーション値R(θ)を測定した。θは30°~50°とした。
iv)測定されたR0およびR(θ)と、前述の平均屈折率と膜厚とから、王子計測機器社製KOBRA-21ADHにより、nx、nyおよびnzを算出し、Rthを算出した。レターデーションの測定は、23℃55%RH条件下で行った。 4) Retardation Rth
i) The average refractive index of the film was measured with a refractometer.
ii) Retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the film normal direction was incident was measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
iii) With KOBRA-21ADH manufactured by Oji Scientific Instruments, the retardation value R (θ) was measured when light having a wavelength of 590 nm was incident from the angle θ (incident angle (θ)) with respect to the film normal direction. . θ was 30 ° to 50 °.
iv) From the measured R 0 and R (θ) and the above-described average refractive index and film thickness, nx, ny and nz were calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.
i)フィルムの平均屈折率を屈折計により測定した。
ii)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向からの波長590nmの光を入射させたときの面内方向のレターデーションR0を測定した。
iii)王子計測機器社製KOBRA-21ADHにより、フィルム法線方向に対してθの角度(入射角(θ))から波長590nmの光を入射させたときのレターデーション値R(θ)を測定した。θは30°~50°とした。
iv)測定されたR0およびR(θ)と、前述の平均屈折率と膜厚とから、王子計測機器社製KOBRA-21ADHにより、nx、nyおよびnzを算出し、Rthを算出した。レターデーションの測定は、23℃55%RH条件下で行った。 4) Retardation Rth
i) The average refractive index of the film was measured with a refractometer.
ii) Retardation R 0 in the in-plane direction when light having a wavelength of 590 nm from the film normal direction was incident was measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
iii) With KOBRA-21ADH manufactured by Oji Scientific Instruments, the retardation value R (θ) was measured when light having a wavelength of 590 nm was incident from the angle θ (incident angle (θ)) with respect to the film normal direction. . θ was 30 ° to 50 °.
iv) From the measured R 0 and R (θ) and the above-described average refractive index and film thickness, nx, ny and nz were calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.
得られるフィルムのRthは、±3nm以下であることが好ましい。
The Rth of the obtained film is preferably ± 3 nm or less.
5)リワーク性
偏光子の作製
厚さ120μmの長尺ロールポリビニルアルコールフィルムを沃素1質量部、ホウ酸4質量部を含む水溶液100質量部に浸漬し、50℃で、搬送方向の延伸倍率6倍に延伸して、厚み35μmの偏光子を得た。 5) Reworkability Production of Polarizer A 120-μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and the draw ratio in the conveyance direction was 6 times at 50 ° C. To obtain a polarizer having a thickness of 35 μm.
偏光子の作製
厚さ120μmの長尺ロールポリビニルアルコールフィルムを沃素1質量部、ホウ酸4質量部を含む水溶液100質量部に浸漬し、50℃で、搬送方向の延伸倍率6倍に延伸して、厚み35μmの偏光子を得た。 5) Reworkability Production of Polarizer A 120-μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and the draw ratio in the conveyance direction was 6 times at 50 ° C. To obtain a polarizer having a thickness of 35 μm.
偏光板の作製
以下に示されるように、得られた光学フィルムをアルカリケン化処理した後、水洗、中和および水洗した。その後、得られた光学フィルムを80℃で乾燥させた。
ケン化工程 2M-NaOH 50℃ 90秒
水洗工程 水 30℃ 45秒
中和工程 10質量%HCl 30℃ 45秒
水洗工程 水 30℃ 45秒 Production of Polarizing Plate As shown below, the obtained optical film was alkali saponified, then washed with water, neutralized and washed with water. Thereafter, the obtained optical film was dried at 80 ° C.
Saponification process 2M-NaOH 50 ° C. 90 seconds Waterwashing process Water 30 ° C. 45 seconds Neutralization process 10% by mass HCl 30 ° C. 45 seconds Water washing process Water 30 ° C. 45 seconds
以下に示されるように、得られた光学フィルムをアルカリケン化処理した後、水洗、中和および水洗した。その後、得られた光学フィルムを80℃で乾燥させた。
ケン化工程 2M-NaOH 50℃ 90秒
水洗工程 水 30℃ 45秒
中和工程 10質量%HCl 30℃ 45秒
水洗工程 水 30℃ 45秒 Production of Polarizing Plate As shown below, the obtained optical film was alkali saponified, then washed with water, neutralized and washed with water. Thereafter, the obtained optical film was dried at 80 ° C.
Saponification process 2M-NaOH 50 ° C. 90 seconds Water
同様にして、コニカミノルタオプト(株)製KC4UYもアルカリケン化処理した。そして、前述の偏光子の一方の面にアルカリケン化処理したKC4UYを、完全ケン化型ポリビニルアルコール5%水溶液を接着剤として貼り合わせた。同様に、偏光子の他方の面にアルカリケン化処理した光学フィルムを、完全ケン化型ポリビニルアルコール5%水溶液を接着剤として貼り合わせた。貼り合わせは、偏光子の透過軸と光学フィルムの面内遅相軸とが平行になるように行った。貼り合わせた積層物を乾燥して、偏光板を得た。
Similarly, KC4UY manufactured by Konica Minolta Opto Co., Ltd. was also alkali saponified. Then, KC4UY subjected to alkali saponification treatment was bonded to one surface of the above polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. Similarly, an alkali film saponified optical film was bonded to the other surface of the polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. The bonding was performed so that the transmission axis of the polarizer and the in-plane slow axis of the optical film were parallel. The laminated laminate was dried to obtain a polarizing plate.
粘着剤組成物の作製
n-ブチルアクリレート(n-BA)75質量部、メチルアクリレート(MA)20質量部、2-ヒドロキシアクリレート(2-HEA)5質量部、酢酸エチル100質量部およびアゾビスイソブチロニトリル(AIBN)0.2質量部を反応容器に入れ、反応容器内の空気を窒素ガスで置換した。その後、これらの成分を撹拌しながら、窒素雰囲気下で反応容器内の温度を60℃に昇温し、4時間反応させた。4時間後、トルエン100質量部、α-メチルスチレンダイマー5質量部およびAIBN2質量部を加えて、90℃に昇温し、さらに4時間反応させた。反応後、酢酸エチルで希釈し、固形分20質量%のアクリルポリマー溶液を得た。ポリマー溶液の固形分100質量部にイソシアネート系架橋剤(商品名:コロネートL、日本ポリウレタン(株)製)1.0質量部を添加し、よく撹拌して粘着剤組成物を得た。 Preparation of pressure-sensitive adhesive composition 75 parts by mass of n-butyl acrylate (n-BA), 20 parts by mass of methyl acrylate (MA), 5 parts by mass of 2-hydroxy acrylate (2-HEA), 100 parts by mass of ethyl acetate and azobisiso 0.2 parts by mass of butyronitrile (AIBN) was placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas. Thereafter, while stirring these components, the temperature in the reaction vessel was raised to 60 ° C. in a nitrogen atmosphere and reacted for 4 hours. After 4 hours, 100 parts by mass of toluene, 5 parts by mass of α-methylstyrene dimer and 2 parts by mass of AIBN were added, the temperature was raised to 90 ° C., and the reaction was further continued for 4 hours. After the reaction, it was diluted with ethyl acetate to obtain an acrylic polymer solution having a solid content of 20% by mass. To 100 parts by mass of the solid content of the polymer solution, 1.0 part by mass of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred well to obtain an adhesive composition.
n-ブチルアクリレート(n-BA)75質量部、メチルアクリレート(MA)20質量部、2-ヒドロキシアクリレート(2-HEA)5質量部、酢酸エチル100質量部およびアゾビスイソブチロニトリル(AIBN)0.2質量部を反応容器に入れ、反応容器内の空気を窒素ガスで置換した。その後、これらの成分を撹拌しながら、窒素雰囲気下で反応容器内の温度を60℃に昇温し、4時間反応させた。4時間後、トルエン100質量部、α-メチルスチレンダイマー5質量部およびAIBN2質量部を加えて、90℃に昇温し、さらに4時間反応させた。反応後、酢酸エチルで希釈し、固形分20質量%のアクリルポリマー溶液を得た。ポリマー溶液の固形分100質量部にイソシアネート系架橋剤(商品名:コロネートL、日本ポリウレタン(株)製)1.0質量部を添加し、よく撹拌して粘着剤組成物を得た。 Preparation of pressure-sensitive adhesive composition 75 parts by mass of n-butyl acrylate (n-BA), 20 parts by mass of methyl acrylate (MA), 5 parts by mass of 2-hydroxy acrylate (2-HEA), 100 parts by mass of ethyl acetate and azobisiso 0.2 parts by mass of butyronitrile (AIBN) was placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas. Thereafter, while stirring these components, the temperature in the reaction vessel was raised to 60 ° C. in a nitrogen atmosphere and reacted for 4 hours. After 4 hours, 100 parts by mass of toluene, 5 parts by mass of α-methylstyrene dimer and 2 parts by mass of AIBN were added, the temperature was raised to 90 ° C., and the reaction was further continued for 4 hours. After the reaction, it was diluted with ethyl acetate to obtain an acrylic polymer solution having a solid content of 20% by mass. To 100 parts by mass of the solid content of the polymer solution, 1.0 part by mass of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred well to obtain an adhesive composition.
剥離処理したフィルム上に、得られた粘着剤組成物を、乾燥厚みが25μmとなるように塗布して粘着剤層を形成し、粘着シートを得た。
The obtained pressure-sensitive adhesive composition was applied onto the peeled film so as to have a dry thickness of 25 μm to form a pressure-sensitive adhesive layer, thereby obtaining a pressure-sensitive adhesive sheet.
前述の偏光板を100×100mmサイズに打ち抜いた。得られた偏光板の一方の面に、粘着シートの粘着剤層を転写して、粘着剤付き偏光板を得た。粘着剤付き偏光板を、ガラス基板と貼り合わせた。4角の1カ所から、偏光板をガラス基板から少し剥離し、剥離した偏光板を掴みガラス基板を押さえながら対角方向に剥離した。同様の操作を計10枚のサンプルで実施し、以下の基準に従い評価を行った。
○:10枚とも光学フィルムが裂けることなく完全に剥離できた
△:1~5枚で光学フィルムが裂けて一部がガラス基板上に残り、剥離残りが生じた
×:6枚以上で光学フィルムが裂けて一部がガラス基板上に残り、剥離残りが生じた The aforementioned polarizing plate was punched into a size of 100 × 100 mm. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was transferred to one surface of the obtained polarizing plate to obtain a pressure-sensitive adhesive-attached polarizing plate. The polarizing plate with an adhesive was bonded to the glass substrate. The polarizing plate was slightly peeled from the glass substrate from one of the four corners, and was peeled diagonally while holding the peeled polarizing plate and holding the glass substrate. The same operation was performed on a total of 10 samples, and evaluation was performed according to the following criteria.
○: All 10 sheets were able to be completely peeled without tearing. Δ: The optical film was torn with 1 to 5 sheets, and part of the film remained on the glass substrate. Torn and part of it remained on the glass substrate, resulting in peeling residue
○:10枚とも光学フィルムが裂けることなく完全に剥離できた
△:1~5枚で光学フィルムが裂けて一部がガラス基板上に残り、剥離残りが生じた
×:6枚以上で光学フィルムが裂けて一部がガラス基板上に残り、剥離残りが生じた The aforementioned polarizing plate was punched into a size of 100 × 100 mm. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was transferred to one surface of the obtained polarizing plate to obtain a pressure-sensitive adhesive-attached polarizing plate. The polarizing plate with an adhesive was bonded to the glass substrate. The polarizing plate was slightly peeled from the glass substrate from one of the four corners, and was peeled diagonally while holding the peeled polarizing plate and holding the glass substrate. The same operation was performed on a total of 10 samples, and evaluation was performed according to the following criteria.
○: All 10 sheets were able to be completely peeled without tearing. Δ: The optical film was torn with 1 to 5 sheets, and part of the film remained on the glass substrate. Torn and part of it remained on the glass substrate, resulting in peeling residue
6)偏光子の劣化
5)のリワーク性の評価で作製した偏光板の全光線透過率を、日本電色工業(株)製濁度計NDH2000を用いて測定した。全光線透過率の測定では、測定時の光の偏光の影響をキャンセルするために、偏光板の全光線透過率を、偏光子の吸収軸が水平方向となるようにして測定し、さらに偏光子の吸収軸が水平方向に対して直交する方向(垂直方向)となるようにさらに測定し(合計2回測定し)、それらの平均値を算出した。次いで、偏光板を、60℃90%RHの条件で2000時間保存して耐久性試験を行った後、前述と同様の方法で、耐久性試験後の偏光板の全光線透過率を測定した。得られた値を下記式にそれぞれ当てはめて、耐久性試験前後での全光線透過率の変化量を算出した。
全光線透過率の変化量=(耐久性試験後の全光線透過率)-(耐久性試験前の全光線透過率) 6) Degradation of polarizer The total light transmittance of the polarizing plate produced in the evaluation of reworkability in 5) was measured using a turbidimeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. In measuring the total light transmittance, in order to cancel the influence of the polarization of light at the time of measurement, the total light transmittance of the polarizing plate is measured so that the absorption axis of the polarizer is in the horizontal direction. Were further measured (measured twice in total) so that their absorption axes were in a direction perpendicular to the horizontal direction (vertical direction), and an average value thereof was calculated. Next, after the polarizing plate was stored for 2000 hours at 60 ° C. and 90% RH and subjected to a durability test, the total light transmittance of the polarizing plate after the durability test was measured by the same method as described above. The obtained values were respectively applied to the following formulas, and the amount of change in the total light transmittance before and after the durability test was calculated.
Change amount of total light transmittance = (total light transmittance after durability test) − (total light transmittance before durability test)
5)のリワーク性の評価で作製した偏光板の全光線透過率を、日本電色工業(株)製濁度計NDH2000を用いて測定した。全光線透過率の測定では、測定時の光の偏光の影響をキャンセルするために、偏光板の全光線透過率を、偏光子の吸収軸が水平方向となるようにして測定し、さらに偏光子の吸収軸が水平方向に対して直交する方向(垂直方向)となるようにさらに測定し(合計2回測定し)、それらの平均値を算出した。次いで、偏光板を、60℃90%RHの条件で2000時間保存して耐久性試験を行った後、前述と同様の方法で、耐久性試験後の偏光板の全光線透過率を測定した。得られた値を下記式にそれぞれ当てはめて、耐久性試験前後での全光線透過率の変化量を算出した。
全光線透過率の変化量=(耐久性試験後の全光線透過率)-(耐久性試験前の全光線透過率) 6) Degradation of polarizer The total light transmittance of the polarizing plate produced in the evaluation of reworkability in 5) was measured using a turbidimeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. In measuring the total light transmittance, in order to cancel the influence of the polarization of light at the time of measurement, the total light transmittance of the polarizing plate is measured so that the absorption axis of the polarizer is in the horizontal direction. Were further measured (measured twice in total) so that their absorption axes were in a direction perpendicular to the horizontal direction (vertical direction), and an average value thereof was calculated. Next, after the polarizing plate was stored for 2000 hours at 60 ° C. and 90% RH and subjected to a durability test, the total light transmittance of the polarizing plate after the durability test was measured by the same method as described above. The obtained values were respectively applied to the following formulas, and the amount of change in the total light transmittance before and after the durability test was calculated.
Change amount of total light transmittance = (total light transmittance after durability test) − (total light transmittance before durability test)
得られた全光線透過率の変化量に基づいて、偏光子劣化を以下のように評価した。
○:全光線透過率の変化量が5%以下
△:全光線透過率の変化量が5%超10%以下
×:全光線透過率の変化量が10%超
○レベルであることが好ましいが、△レベルであれば実用上問題ない。 Based on the amount of change in the total light transmittance obtained, the polarizer deterioration was evaluated as follows.
○: Change in total light transmittance is 5% or less. Δ: Change in total light transmittance is more than 5% and 10% or less. X: Change in total light transmittance is more than 10%. If it is △ level, there is no practical problem.
○:全光線透過率の変化量が5%以下
△:全光線透過率の変化量が5%超10%以下
×:全光線透過率の変化量が10%超
○レベルであることが好ましいが、△レベルであれば実用上問題ない。 Based on the amount of change in the total light transmittance obtained, the polarizer deterioration was evaluated as follows.
○: Change in total light transmittance is 5% or less. Δ: Change in total light transmittance is more than 5% and 10% or less. X: Change in total light transmittance is more than 10%. If it is △ level, there is no practical problem.
実施例1~14の光学フィルムの評価結果を表1に示し;比較例1~13の光学フィルムの評価結果を表2に示し;実施例15~16および比較例14の光学フィルムの評価結果を表3に示し;比較例15~18の評価結果を表4に示す。
The evaluation results of the optical films of Examples 1 to 14 are shown in Table 1, the evaluation results of the optical films of Comparative Examples 1 to 13 are shown in Table 2, and the evaluation results of the optical films of Examples 15 to 16 and Comparative Example 14 are shown. Table 4 shows the evaluation results of Comparative Examples 15 to 18.
酸トラップ剤であるLBT1830またはアデカサイザーD-32を含有する実施例1~16のフィルムは、酸トラップ剤を含有しない比較例1~13のフィルムよりも破断応力および引き裂き強度が高く、かつ着色が生じないことがわかる。
The films of Examples 1 to 16 containing LBT1830 or Adekasizer D-32 which are acid trapping agents have higher breaking stress and tear strength than the films of Comparative Examples 1 to 13 containing no acid trapping agent, and are colored. It turns out that it does not occur.
また、高い溶融温度で製膜された実施例1~2のフィルムは、低い溶融温度で製膜された実施例3~4のフィルムよりも、リワーク性が高く、着色も生じないことがわかる。実施例1~2のフィルムにおいて着色しなかったのは、酸トラップ剤を含有させることで、溶融温度を高くしたときの樹脂の熱劣化を抑制できたためと考えられる。実施例1~2のフィルムのリワーク性が高いのは、溶融温度を高めることで、(メタ)アクリル樹脂とセルロースエステルとを含む樹脂組成物の流動性を高めることができ、得られるフィルムの柔軟性が向上したためと考えられる。
It can also be seen that the films of Examples 1 and 2 formed at a high melting temperature have higher reworkability and no coloration than the films of Examples 3 and 4 formed at a low melting temperature. The reason why the films of Examples 1 and 2 were not colored is considered to be that the thermal deterioration of the resin when the melting temperature was increased could be suppressed by containing an acid trapping agent. The high reworkability of the films of Examples 1 and 2 is that the fluidity of the resin composition containing (meth) acrylic resin and cellulose ester can be increased by increasing the melting temperature, and the flexibility of the resulting film This is thought to be due to the improvement in performance.
実施例4~8の対比から、酸トラップ剤の含有量が少なすぎると、得られるフィルムの着色が若干生じやすく;酸トラップ剤の含有量が多すぎると、得られるフィルムが若干ブリードアウトを生じやすく、偏光子を劣化させやすいことがわかる。
From the comparison of Examples 4 to 8, when the content of the acid trapping agent is too small, the resulting film is slightly colored; when the content of the acid trapping agent is too large, the resulting film slightly bleeds out. It turns out that it is easy to deteriorate a polarizer.
実施例3と9~12の対比から、(メタ)アクリル樹脂の含有比率が多すぎると、得られるフィルムが若干脆くなりやすく、引き裂き強度が若干低下しやすいことが示唆される。一方、セルロースエステルの含有比率が多すぎると、得られるフィルムの着色が若干生じやすいことがわかる。
The comparison between Example 3 and 9 to 12 suggests that if the content ratio of the (meth) acrylic resin is too large, the resulting film tends to be slightly brittle and the tear strength tends to decrease slightly. On the other hand, when the content ratio of the cellulose ester is too large, it can be seen that the resulting film is slightly colored.
実施例3と13~14の対比から、ラクトン環を含有する(メタ)アクリル樹脂を含むフィルムは、ラクトン環を含有しない(メタ)アクリル樹脂を含むフィルムよりもフィルム強度が高く、リワーク性が高いことがわかる。ラクトン環を含有する(メタ)アクリル樹脂を含むフィルムの強度が高いのは、ラクトン環を含有する(メタ)アクリル樹脂の主鎖に含まれる未環化の水酸基含有モノマー由来の構成単位同士が水素結合を形成し、かつ当該(メタ)アクリル樹脂とセルロースエステルとの相溶性も高いためであると考えられる。
From the comparison between Examples 3 and 13 to 14, the film containing the (meth) acrylic resin containing the lactone ring has higher film strength and higher reworkability than the film containing the (meth) acrylic resin containing no lactone ring. I understand that. The strength of the film containing the (meth) acrylic resin containing the lactone ring is high because the structural units derived from the uncyclized hydroxyl group-containing monomer contained in the main chain of the (meth) acrylic resin containing the lactone ring are hydrogen. It is considered that this is because a bond is formed and the compatibility between the (meth) acrylic resin and the cellulose ester is high.
実施例16に示されるように、膜厚が10μm程度と薄いフィルムであっても、酸トラップ剤を含むことで、一定以上の引き裂き強度を有し、良好なリワーク性を示すことがわかる。
As shown in Example 16, it can be seen that even a thin film having a film thickness of about 10 μm has a tear strength of a certain level or more and exhibits good reworkability by including an acid trapping agent.
一方、比較例1のフィルムは、得られるフィルムが着色したり、Rthが若干高くなったりすることがわかる。比較例1のフィルムは酸トラップ剤を含有しないため、高い溶融温度によって樹脂が熱劣化したものと考えられる。また、熱劣化した樹脂を含むフィルムのRthが高いのは、セルロースエステルの側鎖が分解したためであると考えられる。また、熱劣化した樹脂を含むフィルムは脆いため、リワーク性も低いことがわかる。
On the other hand, it can be seen that in the film of Comparative Example 1, the resulting film is colored or the Rth is slightly increased. Since the film of Comparative Example 1 does not contain an acid trapping agent, it is considered that the resin was thermally deteriorated due to a high melting temperature. Moreover, it is considered that the Rth of the film containing the thermally deteriorated resin is high because the side chain of the cellulose ester is decomposed. Moreover, since the film containing the resin which carried out heat deterioration is weak, it turns out that rework property is also low.
本発明の光学フィルムは、(メタ)アクリル樹脂を主成分として含み、着色がなく、膜厚が薄く、かつリワーク性に優れている。
The optical film of the present invention contains (meth) acrylic resin as a main component, is not colored, has a thin film thickness, and is excellent in reworkability.
10 フィルムの製造装置
12 押し出し機
14 ダイ
16、18、20 冷却ロール
22 剥離ロール
24 延伸装置
26 巻き取り装置
28 フィルタ
30 スタチックミキサ
32 弾性タッチロール
110 液晶表示装置
120 液晶セル
140 第一の偏光板
142 第一の偏光子
144 保護フィルム(F1)
146 保護フィルム(F2)
160 第二の偏光板
162 第二の偏光子
164 保護フィルム(F3)
166 保護フィルム(F4)
180 バックライト DESCRIPTION OFSYMBOLS 10 Film manufacturing apparatus 12 Extruder 14 Die 16, 18, 20 Cooling roll 22 Peeling roll 24 Stretching apparatus 26 Winding apparatus 28 Filter 30 Static mixer 32 Elastic touch roll 110 Liquid crystal display apparatus 120 Liquid crystal cell 140 First polarizing plate 142 First Polarizer 144 Protective Film (F1)
146 Protective Film (F2)
160 2ndpolarizing plate 162 2nd polarizer 164 Protective film (F3)
166 protective film (F4)
180 backlight
12 押し出し機
14 ダイ
16、18、20 冷却ロール
22 剥離ロール
24 延伸装置
26 巻き取り装置
28 フィルタ
30 スタチックミキサ
32 弾性タッチロール
110 液晶表示装置
120 液晶セル
140 第一の偏光板
142 第一の偏光子
144 保護フィルム(F1)
146 保護フィルム(F2)
160 第二の偏光板
162 第二の偏光子
164 保護フィルム(F3)
166 保護フィルム(F4)
180 バックライト DESCRIPTION OF
146 Protective Film (F2)
160 2nd
166 protective film (F4)
180 backlight
Claims (19)
- (メタ)アクリル樹脂と、酸トラップ剤とを含有する組成物を含み、
破断応力が70MPa以上であり、かつ引き裂き強度が10mN以上であり、
膜厚が10~45μmである、光学フィルム。 Including a composition containing a (meth) acrylic resin and an acid trapping agent;
The breaking stress is 70 MPa or more, and the tear strength is 10 mN or more,
An optical film having a thickness of 10 to 45 μm. - 前記酸トラップ剤が、アルキルリン酸金属塩である、請求項1に記載の光学フィルム。 The optical film according to claim 1, wherein the acid trapping agent is an alkyl phosphate metal salt.
- 前記酸トラップ剤の含有量は、前記組成物に対して0.1~5質量%である、請求項1に記載の光学フィルム。 2. The optical film according to claim 1, wherein the content of the acid trapping agent is 0.1 to 5% by mass with respect to the composition.
- 前記酸トラップ剤の含有量は、前記組成物に対して0.1~5質量%である、請求項2に記載の光学フィルム。 The optical film according to claim 2, wherein the content of the acid trapping agent is 0.1 to 5% by mass with respect to the composition.
- 前記組成物が、セルロースエステルをさらに含有する、請求項1に記載の光学フィルム。 The optical film according to claim 1, wherein the composition further contains a cellulose ester.
- 前記組成物が、セルロースエステルをさらに含有する、請求項2に記載の光学フィルム。 The optical film according to claim 2, wherein the composition further contains a cellulose ester.
- 前記セルロースエステルが、セルロースアセテートプロピオネートである、請求項5に記載の光学フィルム。 The optical film according to claim 5, wherein the cellulose ester is cellulose acetate propionate.
- 前記セルロースエステルが、セルロースアセテートプロピオネートである、請求項6に記載の光学フィルム。 The optical film according to claim 6, wherein the cellulose ester is cellulose acetate propionate.
- 前記(メタ)アクリル樹脂と前記セルロースエステルの含有比率は、質量比で(メタ)アクリル樹脂/セルロースエステル=90/10~50/50である、請求項5に記載の光学フィルム。 6. The optical film according to claim 5, wherein a content ratio of the (meth) acrylic resin and the cellulose ester is (meth) acrylic resin / cellulose ester = 90/10 to 50/50 in mass ratio.
- 前記(メタ)アクリル樹脂と前記セルロースエステルの含有比率は、質量比で(メタ)アクリル樹脂/セルロースエステル=90/10~50/50である、請求項6に記載の光学フィルム。 7. The optical film according to claim 6, wherein a content ratio of the (meth) acrylic resin and the cellulose ester is (meth) acrylic resin / cellulose ester = 90/10 to 50/50 by mass ratio.
- 前記(メタ)アクリル樹脂がラクトン環構造を有する、請求項1に記載の光学フィルム。 The optical film according to claim 1, wherein the (meth) acrylic resin has a lactone ring structure.
- 前記組成物が、アクリロニトリル・スチレン共重合体をさらに含有する、請求項1に記載の光学フィルム。 The optical film according to claim 1, wherein the composition further contains an acrylonitrile / styrene copolymer.
- 請求項1に記載の光学フィルムを含む、偏光板保護フィルム。 A polarizing plate protective film including the optical film according to claim 1.
- 下記式で定義され、波長590nmにおいて測定される厚み方向のレターデーションRthが-5nm以上5nm以下である、請求項13に記載の偏光板保護フィルム。
Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向の屈折率、ny:フィルム面内において、遅相軸に対して直交する方向の屈折率、nz:厚み方向におけるフィルムの屈折率、d:フィルムの厚み(nm)) The polarizing plate protective film according to claim 13, which is defined by the following formula and has a thickness direction retardation Rth measured at a wavelength of 590 nm of −5 nm to 5 nm.
Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm)) - 偏光子と、前記偏光子の少なくとも一方の面に配置された請求項13に記載の偏光板保護フィルムとを含む、偏光板。 A polarizing plate comprising a polarizer and the polarizing plate protective film according to claim 13 disposed on at least one surface of the polarizer.
- 液晶セルと、前記液晶セルの少なくとも一方の面に配置された請求項15に記載の偏光板とを含む、液晶表示装置。 A liquid crystal display device comprising: a liquid crystal cell; and the polarizing plate according to claim 15 disposed on at least one surface of the liquid crystal cell.
- 請求項1に記載の光学フィルムの製造方法であって、
前記(メタ)アクリル樹脂と、前記酸トラップ剤とを含有する樹脂組成物を、溶融混練した後、フィルム状に押し出すステップを含む、光学フィルムの製造方法。 It is a manufacturing method of the optical film according to claim 1,
A method for producing an optical film, comprising melt-kneading a resin composition containing the (meth) acrylic resin and the acid trapping agent and then extruding the resin composition into a film. - 前記樹脂組成物が、セルロースエステルをさらに含有する、請求項17に記載の光学フィルムの製造方法。 The method for producing an optical film according to claim 17, wherein the resin composition further contains a cellulose ester.
- 前記樹脂組成物の溶融温度は、240~270℃である、請求項17に記載の光学フィルムの製造方法。 The method for producing an optical film according to claim 17, wherein the melting temperature of the resin composition is 240 to 270 ° C.
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