WO2018070132A1 - 偏光板および液晶表示装置 - Google Patents
偏光板および液晶表示装置 Download PDFInfo
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- WO2018070132A1 WO2018070132A1 PCT/JP2017/031508 JP2017031508W WO2018070132A1 WO 2018070132 A1 WO2018070132 A1 WO 2018070132A1 JP 2017031508 W JP2017031508 W JP 2017031508W WO 2018070132 A1 WO2018070132 A1 WO 2018070132A1
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- film
- acid
- protective film
- polarizing plate
- liquid crystal
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
Definitions
- the present invention relates to a polarizing plate and an IPS (In Plane Switching) type liquid crystal display device including the polarizing plate.
- IPS In Plane Switching
- Patent Document 1 Conventionally, as a technique for improving display unevenness in a liquid crystal display device, for example, there is one disclosed in Patent Document 1.
- a thin liquid crystal display device for example, an IPS type liquid crystal display device
- an aliphatic dicarboxylic acid is used to solve the problem of occurrence of circular or elliptical light unevenness on the display surface.
- a polycondensation ester of an acid and an aliphatic diol as a plasticizer and containing the plasticizer in an amount of 10% by mass or more with respect to a polymer (preferably cellulose acylate) that forms an optical film, Has improved.
- the protective film positioned on the viewer side with respect to the polarizer is composed of a film having low moisture permeability, thereby reducing the water absorption of the polarizing plate, thereby suppressing the dimensional change, and thereby the liquid crystal I tried to suppress the cell bend.
- the film having low moisture permeability include resin films such as PET (polyethylene terephthalate) and acrylic. These films are formed by, for example, a melt casting film forming method.
- JP 2013-254190 A see claims 9, 10, 23, paragraphs [0037] to [0043], [0215], etc.
- the protective film located on the viewing side with respect to the polarizer is also referred to as a T1 film, and the liquid crystal cell with respect to the polarizer.
- the protective film located on the side is also referred to as a T2 film.
- a polarizing plate disposed on the viewing side with respect to the liquid crystal cell is required to have a function of absorbing ultraviolet rays.
- Such an ultraviolet absorbing function can be imparted, for example, by adding an ultraviolet absorber to the T1 film.
- the melt casting film forming method is suitable for melting because additives such as ultraviolet absorbers are melted by heat. Therefore, it is generally not easy to add an additive, so that the productivity of the film is lowered and the production cost is increased. If the additive is forcibly added, bleeding out (exudation of the additive) occurs, and when the formed film is applied to the polarizing plate, the quality of the polarizing plate may be impaired.
- the present inventor intends to prevent deterioration of the liquid crystal cell by adding an ultraviolet absorber to the T2 film in the polarizing plate on the viewing side with respect to the liquid crystal cell, thereby providing the T2 film with an ultraviolet absorbing function. investigated.
- an ultraviolet absorber is added to the T2 film, bend unevenness is caused due to the addition, and durability of the T2 film is deteriorated.
- realization of a polarizing plate capable of suppressing bend unevenness and durability deterioration is desired.
- an IPS type liquid crystal display device equipped with a high transmittance panel since the amount of transmitted light is large, display unevenness is easily recognized, and it is important to suppress bend unevenness.
- the expression principle of bend unevenness is estimated as follows.
- cracks occur in the film formed because the compatibility between the ultraviolet absorber and the resin constituting the film (for example, cellulose ester resin) is poor.
- Moisture that has permeated even a little through the T1 film with low moisture permeability tends to accumulate in the cracked portion of the T2 film, and the T2 film causes dimensional fluctuations due to the accumulated moisture. For this reason, a bend occurs in the liquid crystal cell, and image unevenness (bend unevenness) due to the bend occurs.
- the deterioration of the durability of the T2 film is considered as follows.
- fine particles matrix agent
- a UV absorber is further added to the film (dope) during film formation, aggregation of the fine particles and the UV absorber proceeds during the film forming process.
- the above aggregation is performed over the entire film.
- the haze of the entire film deteriorates, and the durability of the T2 film (for example, haze after a wet heat durability test) also deteriorates.
- the present invention has been made in order to solve the above-described problems.
- the object of the present invention is to suppress bend unevenness when applied to an IPS type liquid crystal display device and to protect the liquid crystal cell side of the viewing side polarizing plate. It is providing the polarizing plate which can suppress the durable deterioration of a film (T2 film), and a liquid crystal display device provided with the polarizing plate.
- the polarizing plate according to one aspect of the present invention is a polarizing plate in which a first protective film, a polarizer, and a second protective film are laminated in this order,
- (I) Ro (nx ⁇ ny) ⁇ d
- Rt ((nx + ny) / 2 ⁇ nz) ⁇ d
- nx is the refractive index in the slow axis direction in the film plane
- ny is the refractive index in the fast axis direction in the film plane
- nz is the refractive index in the thickness direction of the film (refractive index is 23 ° C., 55%)
- a liquid crystal display device includes: The polarizing plate, An IPS type liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates, The polarizing plate is disposed on the viewing side with respect to the liquid crystal cell, and the second protective film is disposed on the liquid crystal cell side with respect to the polarizer.
- the 2nd protective film which comprises a polarizing plate contains the polyester diol whose both ends of a principal chain are hydroxyl groups, the compatibility of a ultraviolet absorber and resin is formed at the time of film forming of a 2nd protective film. Can be improved. Thereby, it can suppress that a crack generate
- the polarizing plate is applied particularly to an IPS type liquid crystal display device, it is possible to suppress the bend of the liquid crystal cell due to the dimensional variation of the second protective film, thereby suppressing image unevenness (bend unevenness).
- the second protective film is composed of a laminated film, and the outermost layer (skin layer) contains fine particles. For this reason, at the time of forming the second protective film, the fine particles and the ultraviolet absorber are aggregated only in the skin layer (not aggregated over the entire film), and haze deterioration in the entire film can be suppressed. it can. Thereby, durability of a 2nd protective film can be improved.
- the polarizing plate of this embodiment is a polarizing plate in which a first protective film, a polarizer, and a second protective film are laminated in this order.
- the retardation value Ro (nm) in the film in-plane direction defined by the following formula (i) and the retardation value Rt (nm) in the thickness direction of the film defined by the following formula (ii) are The conditions specified by the following formulas (iii) and (iv) are satisfied.
- the second protective film has Ro and Rt defined by the formulas (i) and (ii) represented by the formula ( It is a so-called zero retardation film that satisfies iii) and (iv).
- the second protective film is positioned on the liquid crystal cell side with respect to the polarizer.
- the second protective film contains an ultraviolet absorber
- the types of additives used for forming the first protective film can be reduced. Accordingly, the first protective film can be easily formed by the melt casting film forming method, and the formed first protective film can be applied to the polarizing plate. Needless to say, the first protective film can be formed by a solution casting film forming method.
- the ultraviolet rays are absorbed by the second protective film (ultraviolet absorber) by disposing the polarizing plate on the viewing side of the liquid crystal cell, it is possible to prevent the liquid crystal cell from being deteriorated by the ultraviolet rays. Furthermore, the durability of the second protective film itself due to ultraviolet rays can be suppressed and the durability can be improved.
- the second protective film constituting the polarizing plate contains a polyester diol in which both ends of the main chain are hydroxyl groups. Accordingly, even when the second protective film includes the ultraviolet absorber as in the present embodiment, the ultraviolet absorber and the second protective film are configured at the time of forming the second protective film.
- the compatibility with the resin to be used for example, cellulose ester resin
- the second protective film is composed of a laminated film including a core layer and two skin layers, and the skin layer contains fine particles. For this reason, even when the second protective film includes the ultraviolet absorber as in this embodiment, the aggregation of the fine particles and the ultraviolet absorber is caused by the skin layer when the second protective film is formed. It happens only in the case of the whole film. Thereby, deterioration of the haze in the whole film can be suppressed, and deterioration of durability (for example, haze after a wet heat durability test) of the second protective film can be suppressed.
- the ultraviolet absorber is preferably contained in both the core layer and the two skin layers in the second protective film.
- ultraviolet rays can be absorbed by the entire second protective film (laminated film), and deterioration of the liquid crystal cell due to ultraviolet rays and deterioration of the second protective film itself due to ultraviolet rays can be reliably prevented.
- the polyester diol is preferably contained in both the core layer and the two skin layers in the second protective film.
- the compatibility between the ultraviolet absorber and the resin can be improved over the entire core layer and skin layer. Thereby, it can suppress that a crack generate
- the core layer and the two skin layers may contain a resin made of cellulose ester.
- a film containing a cellulose ester resin can be formed by a solution casting film forming method in which the addition of an additive is relatively easy, and can be easily formed by co-casting three layers including a core layer and two skin layers. can do.
- the 2nd protective film which is a laminated film, and a polarizing plate provided with the same can be easily realized.
- the first protective film preferably contains a resin made of polyethylene terephthalate (PET).
- PET polyethylene terephthalate
- the moisture permeability of the first protective film can be lowered to reduce the water absorption of the polarizing plate, and the bending of the polarizing plate due to the water absorption and the bend unevenness resulting therefrom can be suppressed.
- the second protective film is hardly affected by moisture, the second protective film is also effective in improving the durability.
- the liquid crystal display device of this embodiment includes the polarizing plate of this embodiment described above and an IPS liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates, and the polarizing plate is on the viewing side with respect to the liquid crystal cell. And the second protective film is disposed on the liquid crystal cell side with respect to the polarizer.
- the IPS type liquid crystal display device it is possible to suppress the bend of the substrate and the resulting bend unevenness.
- IPS liquid crystal display devices are particularly susceptible to bend unevenness due to liquid crystal cell characteristics. For this reason, the configuration of the polarizing plate of the present embodiment that suppresses bend unevenness is very effective when the liquid crystal cell is an IPS type.
- FIG. 1 is a cross-sectional view showing a schematic configuration of an IPS liquid crystal display device 1 according to the present embodiment.
- the liquid crystal display device 1 includes a liquid crystal display panel 2 and a backlight 3.
- the backlight 3 is a light source for illuminating the liquid crystal display panel 2.
- the liquid crystal display panel 2 is configured by disposing a polarizing plate 5 on the viewing side of the IPS liquid crystal cell 4 and disposing a polarizing plate 6 on the backlight 3 side.
- the liquid crystal cell 4 is formed by sandwiching a liquid crystal layer between a pair of glass substrates (not shown).
- the polarizing plate 5 includes a polarizer 11 and optical films 12 and 13.
- the polarizer 11 transmits predetermined linearly polarized light.
- the optical film 12 is a first protective film (also referred to as a T1 film) disposed on the viewing side of the polarizer 11.
- the optical film 13 is a second protective film (also referred to as a T2 film) disposed on the liquid crystal cell 4 side of the polarizer 11, that is, on the side opposite to the viewing side with respect to the polarizer 11. Since the optical film 12 is disposed to face the optical film 13 with the polarizer 11 interposed therebetween, the optical film 12 can also be referred to as a counter film.
- the polarizing plate 5 is attached to the viewing side of the liquid crystal cell 4 via an adhesive layer 7. That is, the polarizing plate 5 is bonded to the liquid crystal cell 4 such that the polarizing film 5 is positioned on the viewing side with respect to the liquid crystal cell 4 and the optical film 13 is on the liquid crystal cell 4 side with respect to
- the polarizing plate 6 includes a polarizer 14 and optical films 15 and 16.
- the polarizer 14 transmits predetermined linearly polarized light.
- the optical film 15 is a third protective film (also referred to as a T3 film) disposed on the viewing side (the liquid crystal cell 4 side) of the polarizer 14.
- the optical film 16 is a fourth protective film (also referred to as a T4 film) disposed on the backlight 3 side of the polarizer 14 (the side opposite to the viewing side).
- Such a polarizing plate 6 is attached to the backlight 3 side of the liquid crystal cell 4 via an adhesive layer 8.
- the viewing-side optical film 15 may be omitted, and the polarizer 14 may be in direct contact with the adhesive layer 8.
- the polarizer 11 and the polarizer 14 are disposed so as to be in a crossed Nicols state.
- the second protective film of the polarizing plate on the viewing side will be described.
- the structure of the 2nd protective film shown below is applicable also to the 3rd protective film of the polarizing plate by the side of a backlight.
- the ultraviolet absorber contained in the second protective film may or may not be contained in the third protective film.
- the second protective film of this embodiment is a so-called zero retardation film. That is, in the second protective film, the retardation value Ro (nm) in the film in-plane direction defined by the following formula (i) and the retardation value Rt (nm) in the thickness direction of the film defined by the following formula (ii) Satisfies the conditions defined by the following formulas (iii) and (iv).
- the retardation value Ro ⁇ Rt can be measured according to a known method. Specifically, the retardation values Ro and Rt are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Polarimeter: manufactured by Axometrics) at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. It can be calculated from the obtained refractive indexes nx, ny, and nz by performing a three-dimensional refractive index measurement.
- the polarizing plate is formed into a liquid crystal cell on the second protective film side.
- the polarizing plate and the liquid crystal display device can be further reduced in thickness and weight, which is preferable.
- the second protective film is preferably a light transmissive film having a light transmittance at 380 nm of less than 50%.
- the light transmittance at a wavelength of 380 nm of the second protective film can be determined by measuring using, for example, an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name: V7100).
- the light transmittance at 380 nm is preferably less than 25%, more preferably less than 10%.
- the method for setting the light transmittance at 380 nm to less than 50% is to add an additive having light absorption at 380 nm to the film, and particularly UV absorption having strong absorption in the ultraviolet region. It is effective to add an agent.
- the second protective film of the present embodiment includes a core layer containing cellulose acylate which is a cellulose ester resin, a first skin layer containing cellulose acylate on the surface side of the core layer, and cellulose on the back side of the core layer. And a second skin layer containing acylate.
- the “core layer” refers to the layer having the largest film thickness
- the “skin layer” refers to a layer that is thinner than the core layer and is in contact with the front and back of the core layer.
- the second protective film can be produced by multilayerly casting a dope containing cellulose acylate on a support simultaneously or sequentially to form a film. A state in which a clear interface is not formed may be used.
- cellulose acylate in each layer may be used, or a plurality of cellulose acylates may be mixed in one layer, but it is preferable that the number of cellulose acylates in each layer is one.
- the thickness of the entire second protective film is preferably 3 ⁇ m or more and 50 ⁇ m or less, more preferably 5 ⁇ m or more and 47 ⁇ m or less, and further preferably 7 ⁇ m or more and 45 ⁇ m or less.
- the film thickness is preferable because the strength as a film can be secured, and by setting the film thickness to 50 ⁇ m or less, it is easy to cope with a change in humidity and maintain optical characteristics.
- the thicknesses of the first skin layer and the second skin layer are each preferably from 0.3 ⁇ m to 3 ⁇ m, more preferably from 0.4 ⁇ m to 2.5 ⁇ m, and more preferably from 0.5 ⁇ m to 2.0 ⁇ m. More preferably, it is as follows.
- the film thickness can be measured with, for example, an electronic micrometer K402B manufactured by Anritsu Corporation.
- the cellulose acylate used for the core layer and the skin layer of the second protective film is not particularly limited.
- Examples of cellulose acylate raw materials include cotton linter and wood pulp (hardwood pulp, conifer pulp). Cellulose acylate obtained from any raw material can be used. You may mix and use.
- the ⁇ -1,4-bonded glucose unit constituting cellulose has free hydroxyl groups at the 2nd, 3rd and 6th positions.
- Cellulose acylate is a polymer obtained by acylating part or all of these hydroxyl groups with an acyl group.
- the average degree of acyl substitution means the ratio of acylation of the hydroxyl groups of cellulose located at the 2nd, 3rd and 6th positions (100% acylation has a degree of substitution of 1).
- the method for measuring the degree of acetyl substitution can be carried out in accordance with ASTM (American Testing Materials Association) D-817-91.
- the average acyl substitution degree of the cellulose acylate of the core layer and the average acyl substitution degree of the cellulose acylate of the first skin layer and the second skin layer are each independently 2.00 to 3.00. Yes, preferably 2.50 to 3.00.
- the acyl group having 2 or more carbon atoms of cellulose acylate may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group.
- Preferred examples of these include acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutanoyl group Group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like.
- an acetyl group, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable.
- a propionyl group and a butanoyl group (when the acyl group has 2 to 4 carbon atoms) are preferred, and an acetyl group (when the cellulose acylate is cellulose acetate) is more preferred.
- cellulose acylate for example, cellulose acetate (for example, diacetyl cellulose, triacetyl cellulose), cellulose acetate butyrate, or cellulose acetate propionate can be used.
- an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.
- a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH 3 CH 2 COCl), Basic compounds are used.
- cellulose mixed fatty acid ester The most common industrial synthesis method of cellulose mixed fatty acid ester is to use cellulose corresponding to fatty acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their acid anhydrides. This is a method of acylating with a mixed organic acid component.
- the second protective film preferably contains polyester diol as an additive.
- the structure, molecular weight, and addition amount of the polyester diol are appropriately selected so that the additive compatible with the cellulose acylate dope or the cellulose acylate film exhibits desired characteristics.
- the polyester diol used in this embodiment is that both ends of the main chain are alcoholic hydroxyl groups, compatibility between the cellulose acylate dope or cellulose acylate film and the additive and the control of optical properties are compatible. It is preferable from the point.
- the amount of the polyester diol added is required to be 5% by mass or more based on the cellulose acylate, preferably 9 to 40% by mass, and more preferably 10 to 30% by mass.
- the optical anisotropy in the second protective film containing cellulose acylate it is important to keep the hydroxyl value (OHV) and molecular weight of the polyester diol within a certain range in order to keep the quality constant. is there.
- the hydroxyl value is preferable for quality control.
- the acetic anhydride method described in Japanese Industrial Standard JIS K 1557-1: 2007 can be applied to the measurement of the hydroxyl value.
- the hydroxyl value is preferably from 40 mgKOH / g to 170 mgKOH / g, more preferably from 60 mgKOH / g to 150 mgKOH / g, particularly preferably from 90 mgKOH / g to 140 mgKOH / g.
- the hydroxyl value is too large, the molecular weight tends to be small, the amount of low molecular weight components increases, volatility increases, and this tends to be undesirable.
- the solubility in a solvent and the compatibility with cellulose acylate deteriorate, which tends to be undesirable.
- the number average molecular weight (Mn) of the polyester diol can be determined from calculation from the value of hydroxyl value or measurement of GPC (gel permeation chromatography).
- the molecular weight value is preferably 650 or more and 2800 or less, more preferably 700 or more and 2000 or less, and particularly preferably 800 or more and 1250 or less. In order to make it optically isotropic, those having a molecular weight of 800 or more and 1200 or less are particularly preferably used.
- the polyester diol can be produced by a known method such as a dehydration condensation reaction between a dibasic acid and a glycol, or an addition of a dibasic acid anhydride to a glycol and a dehydration condensation reaction.
- examples of the dibasic acid constituting the polyester diol include succinic acid, glutaric acid, adipic acid, maleic acid, and the like. These may be used alone or in combination of two or more, for example, succinic acid. An acid, adipic acid, or a mixture thereof is preferably used.
- the carbon number of the dibasic acid is preferably 4 to 8, preferably 4 to 6, and particularly preferably 6.
- glycol constituting the polyester diol a suitable one can be selected from various glycols such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, butylene glycol, and the like. However, those having 2 to 4 carbon atoms are preferred, and ethylene glycol having 2 carbon atoms is particularly preferred. This is because the smaller the number of carbons, the better the compatibility with the cellulose ester dope or the cellulose ester film, and the better the bleed-out resistance by wet heat thermostat.
- Fine particles can be added to the second protective film.
- the mat agent is not particularly limited as long as it is a material exhibiting a function of preventing scratches during handling or deterioration of transportability, and an inorganic compound or an organic compound mat agent can be used.
- the inorganic compound matting agent include silicon-containing inorganic compounds (eg, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, zinc oxide, Aluminum oxide, barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, etc. are preferred, and more preferably inorganic compounds containing silicon and zirconium oxide
- silicon dioxide is particularly preferably used.
- silicon dioxide fine particles for example, commercially available products having a trade name such as Aerosil (registered trademark) R972, R974, R812, 200, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used.
- Aerosil registered trademark
- R972, R974, R812, 200, 300, R202, OX50, TT600 above Nippon Aerosil Co., Ltd.
- TT600 above Nippon Aerosil Co., Ltd.
- zirconium oxide for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
- the organic compound matting agent include, for example, polymers such as silicone resin, fluorine resin, and acrylic resin, and among them, silicone resin is preferably used.
- silicone resins those having a three-dimensional network structure are particularly preferable.
- Tospearl (registered trademark) 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120, and Tospearl 240 (above Toshiba Silicone Co., Ltd.)
- a commercial product having a trade name such as “made” can be used.
- the method for adding the matting agent to the cellulose acylate solution is not particularly limited.
- an additive may be included in the stage of mixing cellulose acylate and a solvent, or an additive may be added after preparing a mixed solution of cellulose acylate and solvent.
- a matting agent may be added and mixed immediately before casting the dope, and the mixing can be performed by installing a screw type mixer on-line.
- a static mixer such as an inline mixer is preferable.
- a static mixer SWJ Toray static type in-pipe mixer Hi-Mixer
- a preferred embodiment of the mixing of the matting agent is as described in paragraph No. 0127 of JP2013-75401A.
- the matting agent is contained in at least one of the two skin layers of the second protective film, which is generated when the wide film is wound long by reducing the friction coefficient of the film surface. From the viewpoint of preventing creaking and film breakage. In particular, it is particularly preferable to contain a matting agent in both of the two skin layers from the viewpoint of effectively reducing scratch resistance and creaking. Further, among the skin layer and the core layer of the second protective film, since the matting agent is contained only in the skin layer, the matting agent is dispersed only in the skin layer and is not dispersed throughout the film. Agglomeration does not occur throughout the film and is desirable.
- the content of the matting agent is preferably 0.01 to 5.0% by mass, more preferably 0.03 to 3.0% by mass, and particularly preferably 0.05 to 1.0% by mass.
- the second protective film preferably includes a retardation reducing agent together with cellulose acylate.
- all of the OH groups in the compound (A) having one furanose structure or pyranose structure or a compound (B) in which at least one furanose structure or pyranose structure is bonded by 2 or more and 12 or less it may contain a sugar ester or a sugar ester compound which is a compound partially esterified with an aliphatic acyl group.
- Examples of the preferred compound (A) and compound (B) include the following compounds, but the present invention is not limited to these.
- Examples of the compound (A) include glucose, galactose, mannose, fructose, xylose, arabinose and the like.
- the compound (A) also includes maltitol obtained by reducing maltose with hydrogenation at high pressure.
- examples of the compound (B) include lactose, sucrose, cellobiose, maltose, cellotriose, maltotriose, raffinose, kestose and the like.
- lactose sucrose
- cellobiose maltose
- cellotriose maltotriose
- maltotriose maltotriose
- raffinose kestose
- examples of the compound (B) include lactose, sucrose, cellobiose, maltose, cellotriose, maltotriose, raffinose, kestose and the like.
- sucrose lactose
- sucrose cellobiose
- maltose maltose
- cellotriose maltotriose
- raffinose raffinose
- kestose lactose
- sucrose lactose
- cellobiose maltose
- cellotriose mal
- the monocarboxylic acid used for synthesizing the sugar ester is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, and the like can be used.
- the carboxylic acid used may be one type or a mixture of two or more types.
- Preferred aliphatic monocarboxylic acids include, for example, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecyl acid, Saturation of lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, and laxaric acid
- unsaturated fatty acids such as fatty acids, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- an oligosaccharide esterified compound can be applied as a compound in which 3 to 12 furanose structures or pyranose structures are bonded.
- Oligosaccharide is produced by causing an enzyme such as amylase to act on starch, sucrose, or the like.
- examples of the oligosaccharide applicable to this embodiment include maltooligosaccharide, isomaltooligosaccharide, fructooligosaccharide, galactooligosaccharide, and xylooligosaccharide.
- Oligosaccharides can also be acetylated in the same manner as compounds (A) and (B).
- Acetic anhydride 200 ml was added dropwise to a solution obtained by adding pyridine (100 ml) to glucose (29.8 g, 166 mmol), and allowed to react for 24 hours. Thereafter, the solution was concentrated by evaporation and poured into ice water. After standing for 1 hour, the mixture was filtered through a glass filter to separate the solid and water. The solid on the glass filter was dissolved in chloroform and separated with cold water until it became neutral. The organic layer was separated and dried over anhydrous sodium sulfate.
- glycolose pentaacetate (58.8 g, 150 mmol, 90.9%).
- monocarboxylic acid can be used instead of the acetic anhydride.
- the second protective film contains the above-mentioned sugar ester compound in the range of 1 to 35% by mass, particularly in the range of 5 to 30% by mass, in order to suppress the deterioration of the polarization function and stabilize the display quality. It is preferable to include within. Within this range, the excellent effect of the present embodiment is exhibited, and there is no bleed out during storage of the original fabric, which is preferable. Further, a sugar ester compound in which all OH groups are esterified and a sugar ester compound in which one or more OH groups remain may be used in combination. Examples thereof include a mixture of sucrose octaacetate, sucrose heptaacetate, and sucrose hexaacetate. The mixing ratio is not particularly limited.
- These may be controlled by adjusting the reaction time or the amount of monocarboxylic acid added to react with the sugar during esterification of the sugar, or may be mixed.
- the second protective film may contain an acrylic polymer having a number average molecular weight of 500 or more and 30000 or less as a retardation reducing agent.
- an acrylic polymer those described in paragraphs [0059] to [0093] of International Publication No. WO08 / 044463 are preferably used.
- the second protective film may contain a polyester represented by the following general formula (B1) or (B2) as a retardation reducing agent. This is because the divalent alcohol G having 2 to 12 carbon atoms and the dibasic acid having 2 to 12 carbon atoms, the monocarboxylic acid B 1 having 1 to 12 carbon atoms, or B 2 which is a monoalcohol having 1 to 12 carbon atoms. Is a polyester derived from.
- B 1 represents a monocarboxylic acid having 1 to 12 carbon atoms
- G represents a divalent alcohol having 2 to 12 carbon atoms
- A is a dibasic acid having 2 to 12 carbon atoms To express. It is particularly preferable that B 1 , G, and A each have a small ratio or no aromatic ring ratio.
- m represents the number of repetitions.
- B2 B 2- (AG-) n AB 2
- B 2 represents a monoalcohol having 1 to 12 carbon atoms
- G represents a divalent alcohol having 2 to 12 carbon atoms
- A represents a dibasic acid having 2 to 12 carbon atoms.
- B 2 , G, and A have a small ratio of aromatic rings or do not contain them.
- n represents the number of repetitions.
- the monocarboxylic acids represented by B 1 may be preferably used known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid.
- Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.
- aliphatic monocarboxylic acid a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1-20 carbon atoms, and particularly preferably has 1-12 carbon atoms.
- acetic acid is contained, compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
- Preferred aliphatic monocarboxylic acids include, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, laurin Saturated fatty acids such as acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid And unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.
- the monoalcohol component represented by B 2 is not particularly limited, and known alcohols can be used.
- an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1-20 carbon atoms, and particularly preferably has 1-12 carbon atoms.
- Examples of the divalent alcohol component represented by G include the following, but the present invention is not limited thereto.
- Triethylene glycol is preferable, and 1,3-propylene glycol, 1,4-butylene glycol 1,6-hexanediol, and diethylene glycol are preferably used.
- the dibasic acid (dicarboxylic acid) component represented by A is preferably an aliphatic dibasic acid or an alicyclic dibasic acid.
- the aliphatic dibasic acid malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc.
- particularly as aliphatic dicarboxylic acid Uses at least one selected from those having 4 to 12 carbon atoms. That is, two or more dibasic acids may be used in combination. In that case, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid can be used in combination.
- M and n each represents the number of repetitions, and preferably 1 or more and 170 or less.
- the number average molecular weight of the polyester is preferably 20000 or less, and more preferably 10,000 or less.
- polyesters having a number average molecular weight of 500 to 10,000 are preferable because they have good compatibility with cellulose esters and are less likely to evaporate or volatilize during film formation.
- Polyester polycondensation is performed by conventional methods. For example, a direct reaction of the above dibasic acid and glycol, the above dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or transesterification reaction between a dibasic acid methyl ester and a glycol, or a hot melt condensation method, Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol. It is preferable that the polyester having a number average molecular weight not so large is by direct reaction. Polyester having a high distribution on the low molecular weight side has a very good compatibility with the cellulose ester, and after forming the film, a second protective film having a low moisture permeability and excellent transparency can be obtained.
- the conventional molecular weight adjustment method can be used without any particular limitation.
- a monovalent acid monocarboxylic acid
- monovalent alcohol monoalcohol
- the molecular weight can be adjusted.
- a monovalent acid is preferable from the viewpoint of the stability of the polymer.
- preferable examples of monovalent acids include acetic acid, propionic acid, butyric acid, and the like.
- the number average molecular weight can also be adjusted by measuring the timing at which the reaction is stopped by the amount of water distilled off during the reaction.
- it can be adjusted by biasing the number of moles of glycol or dibasic acid to be charged or by controlling the reaction temperature.
- the polyester of the present embodiment is preferably contained in an amount of 1 to 40% by mass, more preferably 2 to 30% by mass, and particularly preferably 3 to 15% by mass with respect to the second protective film. preferable.
- a polarizing plate With little deterioration due to high temperature and high humidity can be obtained. Further, by using this polarizing plate, an IPS liquid crystal display device that maintains contrast and viewing angle stability for a long time and has excellent surface flatness can be obtained.
- the 2nd protective film can contain a plasticizer as needed.
- the plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like. In addition, these plasticizers may act as a retardation reducing agent.
- the glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.
- alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl
- phthalate ester plasticizer examples include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.
- citrate ester plasticizer examples include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.
- fatty acid ester plasticizer examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like.
- phosphate ester plasticizer examples include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.
- the polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably a divalent to 20valent polyvalent carboxylic acid and an alcohol.
- the aliphatic polyvalent carboxylic acid is preferably divalent to 20-valent, and in the case of an aromatic polyvalent carboxylic acid or alicyclic polyvalent carboxylic acid, it is preferably trivalent to 20-valent.
- the polyvalent carboxylic acid is represented by the following general formula (C).
- R 2 (COOH) m (OH) n
- R 2 is an (m + n) -valent organic group
- m is a positive integer of 2 or more
- n is an integer of 0 or more
- a COOH group is a carboxy group
- an OH group is alcoholic or phenolic hydroxy Represents a group.
- Preferred examples of the polyvalent carboxylic acid include the following, but the present invention is not limited to these.
- Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal
- An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used.
- alcohol used for polyhydric carboxylic acid ester there is no restriction
- an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.
- alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.
- the alcoholic or phenolic hydroxy group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid.
- monocarboxylic acids include the following, but the present invention is not limited thereto.
- aliphatic monocarboxylic acid a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.
- Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.
- the molecular weight of the polyvalent carboxylic acid ester is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improving the retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.
- the alcohol used for the polycarboxylic acid ester may be one kind or a mixture of two or more kinds.
- the acid value of the polyvalent carboxylic acid ester is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. By setting the acid value within the above range, retardation fluctuations are also suppressed, which is preferable.
- the acid value means the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample.
- the acid value is measured according to JIS K0070.
- Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.
- Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.
- the polyester plasticizer is not particularly limited, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. Although it does not specifically limit as a polyester plasticizer, for example, the aromatic terminal ester plasticizer represented by the following general formula (D) can be used.
- B is a benzene monocarboxylic acid residue
- G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene having 4 to 12 carbon atoms
- A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms
- n represents an integer of 1 or more.
- the compound represented by the general formula (D) includes a benzene monocarboxylic acid residue represented by B, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, and an alkylene dicarboxylic acid represented by A. It is composed of a residue or an aryl dicarboxylic acid residue, and can be obtained by the same reaction as a normal polyester plasticizer.
- benzene monocarboxylic acid component of the polyester plasticizer examples include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, and aminobenzoic acid. And acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.
- alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer examples include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1, 2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2 -Diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1, 5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethylene
- Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These glycols include 1 It can be used as a seed or a mixture of two or more.
- alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester examples include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds.
- arylene dicarboxylic acid component having 6 to 12 carbon atoms examples include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.
- the number average molecular weight of the polyester plasticizer is preferably 300 to 1500, more preferably 400 to 1000.
- the acid value is 0.5 mgKOH / g or less, the hydroxy group value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy group value is 15 mgKOH / g or less.
- Example No. 1 (Aromatic terminal ester sample)> A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While the monohydric alcohol was refluxed, heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed at 200 to 230 ° C. under reduced pressure of 1.33 ⁇ 10 4 Pa to finally 4 ⁇ 10 2 Pa or less, and then filtered to remove an aromatic terminal ester plastic having the following properties: An agent was obtained. Viscosity (25 ° C., mPa ⁇ s); 43400 Acid value: 0.2
- Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained. Viscosity (25 ° C., mPa ⁇ s); 31000 Acid value: 0.1
- Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained. Viscosity (25 ° C., mPa ⁇ s); 38000 Acid value: 0.05
- Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained. Viscosity (25 ° C., mPa ⁇ s); 37000 Acid value: 0.05
- ⁇ Ultraviolet absorber> As for a 2nd protective film, it is desirable to contain the ultraviolet absorber which has an ultraviolet-ray absorption function.
- the ultraviolet absorber is the most effective means for making the light transmittance at 380 nm less than 50%.
- the ultraviolet absorber is desirably contained in at least one layer of the second protective film that is a laminated film, but desirably contained in both the core layer and the two skin layers.
- the ultraviolet absorber can improve durability by absorbing ultraviolet rays of 400 nm or less, and can prevent deterioration of the liquid crystal cell due to ultraviolet rays.
- the transmittance at a wavelength of 380 nm is preferably 25% or less, more preferably 10% or less, and still more preferably 5% or less.
- the ultraviolet absorber to be used is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. Can be mentioned.
- Examples of the ultraviolet absorber applicable to this embodiment include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazole) -2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171 Tinuvin such as Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. are all commercially available from BASF Japan, and can be preferably used.
- More preferably used ultraviolet absorbers are benzotriazole compounds, benzophenone compounds, and triazine compounds, particularly preferably benzotriazole compounds and benzophenone compounds.
- benzotriazole-based compound a compound represented by the following general formula (b) can be used.
- R 1 , R 2 , R 3 , R 4 and R 5 may be the same or different, and are a hydrogen atom, a halogen atom, a nitro group, a hydroxy group, an alkyl group, an alkenyl group, an aryl group.
- the carbocyclic ring may be formed.
- these groups described above may have an arbitrary substituent.
- UV-1 2- (2'-hydroxy-5'-methylphenyl) benzotriazole
- UV-2 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole
- UV-3 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole
- UV-4 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole
- UV-5 2- (2′-hydroxy-3 ′-(3 ′′, 4 ′′, 5 ′′, 6 ′′ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole
- UV-6 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
- UV-7 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-ch
- benzophenone compound a compound represented by the following general formula (c) is preferably used.
- Y represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, or a phenyl group, and these alkyl group, alkenyl group, and phenyl group may have a substituent.
- A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a —CO (NH) n-1 -D group
- D represents an alkyl group, an alkenyl group or a substituent.
- the alkyl group represents, for example, a linear or branched aliphatic group having up to 24 carbon atoms
- the alkoxy group represents, for example, an alkoxy group having up to 18 carbon atoms
- the alkenyl group has, for example, carbon number
- An alkenyl group up to 16 represents an allyl group, a 2-butenyl group, or the like.
- alkyl groups alkenyl groups, and phenyl groups
- halogen atoms such as chlorine atoms, bromine atoms, fluorine atoms, etc., hydroxy groups, phenyl groups (this phenyl group is substituted with alkyl groups or halogen atoms, etc.) May be used).
- benzophenone-based compound represented by the general formula (c) Specific examples of the benzophenone-based compound represented by the general formula (c) are shown below, but the present invention is not limited thereto.
- UV-10 2,4-dihydroxybenzophenone
- UV-11 2,2'-dihydroxy-4-methoxybenzophenone
- UV-12 2-hydroxy-4-methoxy-5-sulfobenzophenone
- UV-13 Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
- discotic compounds such as compounds having a 1,3,5 triazine ring are also preferably used as ultraviolet absorbers.
- the ultraviolet absorber in particular, “2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1) shown below is used.
- 3,3-tetramethylbutyl) phenol is preferably used because it can provide a thin film while satisfying both the UV absorption and low retardation of the second protective film.
- the second protective film of the present embodiment can also contain two or more kinds of ultraviolet absorbers.
- a polymeric ultraviolet absorber can also be preferably used, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used.
- the method of adding the UV absorber is to add the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, a solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, or You may add directly in dope composition.
- an alcohol such as methanol, ethanol, butanol
- a solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof
- a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.
- the amount of UV absorber used is not uniform depending on the type of UV absorber, operating conditions, etc., but when the dry thickness of the second protective film is 10 to 100 ⁇ m, it is 0 with respect to the second protective film. It is preferably 5 to 10% by mass, and more preferably 0.6 to 4% by mass.
- the second protective film of the present embodiment includes a core layer forming dope containing a cellulose ester resin, a first skin layer forming dope containing a cellulose ester resin, and a second skin layer forming dope containing a cellulose ester resin.
- a film can be formed by co-casting on a support. At this time, the above three kinds of dopes can be subjected to multilayer casting simultaneously or sequentially on the support.
- the co-cast dope may be dried to form a film, the film may be peeled from the support, and the peeled film may be stretched.
- a 2nd protective film can be manufactured using the solution (dope) which melt
- the organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain.
- the ether, ketone and ester may have a cyclic structure.
- a compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent.
- the organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.
- ether having 3 to 12 carbon atoms examples include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
- ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
- esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
- organic solvent having two or more kinds of functional groups examples include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
- the number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1.
- the halogen of the halogenated hydrocarbon is preferably chlorine.
- the proportion of halogen atoms in the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferably 40 to 60 mol%.
- Methylene chloride is a typical halogenated hydrocarbon.
- Two or more organic solvents may be mixed and used.
- Preparation of the solution can be carried out using a dope preparation method and apparatus in a normal solution casting method.
- a halogenated hydrocarbon particularly, methylene chloride
- the amount of cellulose acylate is preferably adjusted so as to be 10 to 40% by mass in the resulting solution, and more preferably 10 to 30% by mass.
- Arbitrary additives may be added to the organic solvent.
- the solution can be prepared by stirring cellulose acylate and an organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, the cellulose acylate and the organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil.
- the heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., more preferably 80 to 110 ° C.
- Each component may be coarsely mixed in advance and then put into a container, or may be put into a container sequentially.
- the container needs to be configured so that it can be stirred.
- the container can be pressurized by injecting an inert gas such as nitrogen gas.
- a jacket type heating device can be used.
- the entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
- the stirring blade preferably has a length that reaches the vicinity of the wall of the container.
- a scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
- instruments such as a pressure gauge and a thermometer may be installed. Each component is dissolved in a solvent in a container.
- the prepared dope may be taken out of the container after cooling, or may be cooled using a heat exchanger or the like after taking out.
- a cellulose acylate film can be produced from the prepared cellulose acylate solution (dope) by a solution casting method.
- the dope is cast on a drum or band, and the solvent is evaporated to form a film.
- the dope before casting is preferably adjusted in concentration so that the solid content is 10 to 40% by mass.
- the surface of the drum or band is preferably finished in a mirror state.
- the obtained cellulose acylate solution (dope) can be cast on a smooth band or drum as a support to form a film.
- a known co-casting method can be used.
- a film may be produced by laminating and laminating cellulose acylate solutions from a plurality of casting ports provided at intervals in the traveling direction of the metal support.
- JP-A 61-158414 The methods described in JP-A-1-122419, JP-A-11-198285, and the like can be used.
- a film may be formed by casting a cellulose acylate solution from two casting ports.
- JP-B-60-27562, JP-A-61-94724, JP-A-61-947245 It can be carried out by the methods described in JP-A No. 61-104413, JP-A No. 61-158413, and JP-A No. 6-134933.
- a film casting method may be used.
- the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.
- the film cast on the metal support by the first casting port is peeled off, and the second casting is performed on the side that is in contact with the metal support surface, thereby the film.
- Can also be produced for example, Japanese Patent Publication No. 44-20235).
- the cellulose acylate solution can be co-cast to produce a skin layer / core layer / skin layer cellulose acylate film.
- the co-cast dope can be dried and peeled off from the support as a film.
- ⁇ Drying process> A method for drying a film that has been dried on a drum or belt and peeled off is described.
- the film peeled off at the peeling position immediately before the drum or belt makes one turn is conveyed alternately through a group of rolls arranged in a staggered pattern, or both ends of the peeled film are gripped with clips or the like. Then, it is transported by a non-contact transport method. Drying can be performed by a method of applying a wind of a predetermined temperature to both sides of the film being transported or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds.
- the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the film. From this point, for example, as shown in Japanese Patent Application Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferable.
- the drying temperature in the drying step is preferably 100 to 145 ° C. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of the solvents used.
- the film can be stretched.
- the film may be stretched in any direction of the film transport direction (hereinafter also referred to as the film MD direction) and the direction orthogonal to the film transport direction (hereinafter also referred to as the film TD direction), but at least in the film TD direction. It is preferable to stretch the film from the viewpoint of expressing a desired retardation. Furthermore, biaxial stretching combined with stretching in a direction not coincident with the film TD direction (for example, the film MD direction) may be used. Further, the stretching may be performed in one stage or in multiple stages.
- a residual solvent may be included, or the stretching may be performed in a state not including the residual solvent.
- the residual solvent it is preferable that the amount of the solvent is stretched between 0.1% by weight and 50% by weight with respect to the film solid content weight.
- the draw ratios in the biaxial directions orthogonal to each other are preferably finally in the range of 1.0 to 2.0 times in the film MD direction and 1.01 to 2.5 times in the film TD direction, The range is preferably 1.01 to 1.5 times in the film MD direction and 1.05 to 2.0 times in the film MD direction.
- the film surface temperature at the start of stretching is preferably 100 ° C. or higher and 220 ° C. or lower, and more preferably 120 ° C. or higher and 200 ° C. or lower.
- the residual solvent amount of the film at the start of stretching is preferably 0% by mass to 3% by mass, more preferably 0% by mass to 2.3% by mass, More preferably, it is at least 2.1% by mass.
- M is the mass of the film (web) at an arbitrary point in time
- N is the mass when the film whose M is measured is dried at 110 ° C. for 3 hours.
- the film elastic modulus at the start of stretching when stretching in the film TD direction is preferably 100 MPa or more and 1500 MPa or less, more preferably 100 MPa or more and 1000 MPa or less, further preferably 100 MPa or more and 500 MPa or less, It is particularly preferably 100 MPa or more and 300 MPa or less.
- the film elastic modulus is cut out from the center of the film 15 seconds before stretching so that the film MD direction is 10 mm and the film TD direction is 130 mm, and the distance between chucks is measured using the Tensilon Universal Material Testing Machine RTF series (Orientec). It can be measured by conducting a tensile test at a pulling speed of 100 mm% / min.
- a 1st protective film can also be comprised with an acrylic film, and can also be comprised with the polyester film containing a polyester resin (for example, PET resin).
- the acrylic resin and the polyester resin have low moisture permeability, and can be suitably used as a resin constituting the first protective film from the viewpoint of suppressing water content of the film.
- the moisture permeability of acrylic is, for example, 200 g / m 2 ⁇ day when the thickness is 40 ⁇ m
- the moisture permeability of PET resin is, for example, 20 g / m 2 ⁇ day when the thickness is 80 ⁇ m.
- the measurement conditions of moisture permeability are 40 degreeC90% RH.
- the first protective film may be a polyester film having in-plane super-birefringence and a light transmittance of 50% or more at a wavelength of 380 nm.
- having in-plane super birefringence means that the retardation Ro in the in-plane direction is 8000 nm or more.
- the light transmittance at a wavelength of 380 nm in the first protective film is desirably 60 to 95%, more desirably 70 to 95%, and still more desirably 80 to 95%.
- the first protective film as a method of setting the light transmittance at a wavelength of 380 nm to 50% or more, it is effective not to add an additive that absorbs light in the vicinity of a wavelength of 380 nm to the first protective film. It is preferable not to add an ultraviolet absorber that absorbs ultraviolet rays.
- the polyester film of the present embodiment is a stretched polyester film, and the lower limit value of the retardation Ro is preferably 8000 nm and more preferably 10,000 nm from the viewpoint of developing super birefringence.
- the upper limit value of the retardation Ro of the stretched polyester film is such that even if a film having a retardation Ro higher than that is used, a further improvement effect of visibility cannot be substantially obtained, and depending on the size of the retardation Ro. Since the thickness of the film also tends to increase, the thickness is preferably set to 30000 nm from the viewpoint that it may be contrary to the demand for thinning and the handling property as an industrial material is lowered.
- the stretched polyester film has a ratio (Ro / Rt) of the retardation Ro in the in-plane direction to the retardation value Rt in the thickness direction, preferably 0.2 or more, more preferably 0.5 or more, still more preferably. It is 0.6 or more.
- the maximum value of Ro / Rt is 2.0 (that is, a perfect uniaxial symmetry film), but the mechanical strength in the direction perpendicular to the orientation direction tends to decrease as the perfect uniaxial symmetry film is approached. . Therefore, the upper limit of Ro / Rt of the polyester film is preferably 1.2 or less, more preferably 1.0 or less.
- Polyester which is a raw material resin for a stretched polyester film, has excellent transparency and thermal and mechanical properties, and can easily control retardation by stretching.
- polyethylene terephthalate or polyethylene naphthalate is preferable.
- Polyesters typified by polyethylene terephthalate and polyethylene naphthalate are preferable because they have a large intrinsic birefringence and relatively large retardation can be obtained relatively easily even when the film is thin.
- polyethylene naphthalate has a large intrinsic birefringence among polyesters, and therefore is suitable for a case where it is desired to make the retardation particularly high or a case where it is desired to reduce the film thickness while keeping the retardation high.
- the polyester film can be obtained by condensing an arbitrary dicarboxylic acid and a diol.
- dicarboxylic acid examples include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenylcarboxylic acid.
- Acid diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid Acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Dimer , It may be mentioned sebacic acid, suberic acid, dodecamethylene dicarboxylic acid.
- diol examples include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like.
- polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., preferably polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), More preferred is polyethylene terephthalate (PET).
- PET polyethylene terephthalate
- PEN polyethylene naphthalate
- PET polyethylene terephthalate
- the polyester resin may contain other copolymerization components as required. From the viewpoint of mechanical strength, the proportion of the copolymerization component is preferably 3 mol% or less, preferably 2 mol% or less, more preferably 1.5 mol%. It is less than mol%. These resins are excellent in transparency and excellent in thermal and mechanical properties. Moreover, retardation of these resins can be easily controlled by stretching.
- the polyester film can be obtained according to a general production method. Specifically, the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then in the transverse direction by a tenter. Examples thereof include a melt casting method for producing a stretched polyester film by stretching and heat treatment and, if necessary, relaxation treatment.
- the stretched polyester film may be a uniaxially stretched film or a biaxially stretched film.
- the production conditions for obtaining the polyester film can be appropriately set according to a known method.
- the longitudinal stretching temperature and the transverse stretching temperature are usually 80 to 130 ° C., preferably 90 to 120 ° C.
- the longitudinal draw ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times.
- the transverse draw ratio is usually 2.5 to 6.0 times, preferably 3.0 to 5.5 times.
- the retardation can be controlled within a specific range by appropriately setting the stretching ratio, stretching temperature, and film thickness. For example, it becomes easier to obtain high retardation as the difference in draw ratio between longitudinal stretching and transverse stretching is higher, the stretching temperature is lower, and the film thickness is thicker. Conversely, the lower the difference in the draw ratio between the longitudinal and transverse stretching, the higher the stretching temperature, and the thinner the film, the lower the retardation. Moreover, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a lower ratio of retardation value to thickness direction retardation value (Ro / Rt).
- the heat treatment temperature is usually preferably in the range of 140 to 240 ° C, more preferably in the range of 170 to 240 ° C.
- the relaxation treatment temperature is usually in the range of 100 to 230 ° C., more preferably in the range of 110 to 210 ° C., and still more preferably in the range of 120 to 180 ° C.
- the relaxation amount is usually in the range of 0.1 to 20%, preferably in the range of 1 to 10%, and more preferably in the range of 2 to 5%.
- the relaxation treatment temperature and relaxation amount are preferably set so that the thermal shrinkage rate of the polyester film after relaxation treatment at 150 ° C. is 2% or less.
- the orientation main axis means a molecular orientation direction at an arbitrary point on the stretched polyester film.
- stretching direction of an orientation main axis means the angle difference of an orientation main axis
- the maximum value is the maximum value in the direction perpendicular to the long direction.
- the orientation main axis can be measured using, for example, a retardation film / optical material inspection apparatus RETS (manufactured by Otsuka Electronics Co., Ltd.) or a molecular orientation meter MOA (manufactured by Oji Scientific Instruments Co., Ltd.).
- the thickness unevenness of the film is small. If the longitudinal stretching ratio is lowered to give a retardation difference, the value of longitudinal thickness unevenness (hereinafter also referred to as “thickness unevenness”) may be increased. Since there is a region where the value of the vertical thickness unevenness becomes very high in a specific range of the draw ratio, it is desirable to set the film forming conditions so as to exclude such a range.
- the thickness unevenness of the stretched polyester film is preferably 5.0% or less, more preferably 4.5% or less, further preferably 4.0% or less, and 3.0% or less. It is particularly preferred.
- the thickness of the stretched polyester film is arbitrary, and can be appropriately set, for example, within a range of 15 to 300 ⁇ m, preferably within a range of 30 to 200 ⁇ m. In particular, when it is within a range of 60 to 80 ⁇ m, thinning and good visual recognition are possible. It is preferable from the viewpoint that compatibility can be achieved.
- At least one surface of the stretched polyester film may have various functional layers.
- a functional layer include a hard coat layer (also referred to as an ultraviolet curable resin layer), an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, an antireflection antiglare layer, and an antistatic layer.
- a hard coat layer also referred to as an ultraviolet curable resin layer
- an antiglare layer an antireflection layer
- a low reflection layer a low reflection antiglare layer
- an antireflection antiglare layer and an antistatic layer.
- One or more selected from the group consisting of a silicone layer, an adhesive layer, an antifouling layer, an anti-fingerprint layer, a water repellent layer, a blue cut layer, and the like can be used.
- an antiglare layer an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer
- an effect of improving color unevenness when observed from an oblique direction can be expected.
- the refractive index of the easy-adhesion layer can be adjusted by a known method.
- the refractive index of the easy-adhesion layer can be easily adjusted by adding titanium, zirconium, or other metal species to the binder resin.
- the coating solution used for forming the easy-adhesion layer is preferably an aqueous coating solution containing at least one of water-soluble or water-dispersible copolymerized polyester resin, acrylic resin, and polyurethane resin.
- these coating solutions include Japanese Patent Publication No. 6-81714, Japanese Patent No. 3300909, Japanese Patent No. 3632044, Japanese Patent No. 4547644, Japanese Patent No. 4770971, Japanese Patent No. 3567927, and Japanese Patent No. 3589232.
- Examples thereof include water-soluble or water-dispersible copolymerized polyester resin solutions, acrylic resin solutions, polyurethane resin solutions and the like disclosed in Japanese Patent No. 3589233, Japanese Patent No. 3589233, Japanese Patent No. 3900191, and Japanese Patent No. 4150982.
- the first protective film of the present embodiment may be a film containing an acrylic resin (acrylic film).
- Acrylic resins also include methacrylic resins.
- the acrylic film can be produced, for example, by a solution casting film forming method, similarly to the cellulose ester film.
- Tg glass transition temperature
- Tg glass transition temperature
- the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or lower from the viewpoint of moldability and the like.
- any appropriate (meth) acrylic resin can be adopted as long as the effects of the present embodiment are not impaired.
- poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.).
- Preferable examples include C1-6 alkyl poly (meth) acrylates such as poly (meth) acrylate methyl. More preferred is a methyl methacrylate-based resin containing methyl methacrylate as a main component (in the range of 50 to 100% by mass, preferably 70 to 100% by mass).
- the (meth) acrylic resin examples include, for example, Acrypet VH and Acrypet VRL20A, Dianal BR52, BR80, BR83, BR85, BR88 (manufactured by Mitsubishi Rayon Co., Ltd.), KT75 (manufactured by Electrochemical Industry Co., Ltd.) ), Delpet 60N, 80N (manufactured by Asahi Kasei Chemicals Corporation), (meth) acrylic resin having a ring structure in the molecule described in JP-A-2004-70296, by intramolecular crosslinking or intramolecular cyclization reaction. Examples include the obtained high Tg (meth) acrylic resin system.
- the (meth) acrylic resin it is also preferable to use a (meth) acrylic resin having a lactone ring structure.
- examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. No. 146084 and the like.
- an acrylic resin having an unsaturated carboxylic acid alkyl ester structural unit and a glutaric anhydride structural unit can be used as the (meth) acrylic resin.
- the acrylic resin include JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-163924, JP-A-2004-292812, JP-A-2005-314534, JP-A-2006-. Examples described in JP-A-131898, JP-A-2006-206881, JP-A-2006-265532, JP-A-2006-283013, JP-A-2006-299905, JP-A-2006-335902, and the like. It is done.
- thermoplastic resin having a glutarimide unit, a (meth) acrylic acid ester unit, and an aromatic vinyl unit
- thermoplastic resin examples include JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, and JP-A-2006. -337374, JP-A-2006-337493, JP-A-2006-337569, and the like.
- the first protective film preferably has a configuration having an ultraviolet curable resin layer (hereinafter also referred to as a hard coat layer).
- the hard coat layer is a layer for imparting hard coat properties to the surface of the first protective film.
- a hard coat layer forming composition containing an ultraviolet curable resin and a photopolymerization initiator is used to apply the hard coat layer. This is a layer formed by curing an ultraviolet curable resin by ultraviolet irradiation after film formation.
- the ultraviolet curable resin applicable to the present embodiment is not particularly limited as long as it is a resin component having the property of being cured by ultraviolet rays, but as a typical resin material, there is a compound such as a compound having an acrylate functional group. Or the compound which has a 2 or more unsaturated bond can be mentioned. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like.
- Examples of the compound having two or more unsaturated bonds include polymethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol.
- a polyfunctional compound modified with (EO) or the like, or a reaction product of the polyfunctional compound and (meth) acrylate for example, poly (meth) acrylate ester of polyhydric alcohol
- It can gel.
- (Meth) acrylate” refers to methacrylate and acrylate.
- polyester resins In addition to the above compounds, polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyds having a relatively low molecular weight (number average molecular weight of 300 to 80,000, preferably 400 to 5000) having an unsaturated double bond.
- Resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be used as the ultraviolet curable resin.
- the resin in this case includes all dimers, oligomers, and polymers other than monomers.
- Preferred compounds in the present embodiment include compounds having 3 or more unsaturated bonds. When such a compound is used, the crosslink density of the hard coat layer to be formed can be increased, and the coating film hardness can be increased.
- pentaerythritol triacrylate pentaerythritol tetraacrylate
- polyester polyfunctional acrylate oligomer 3 to 15 functional
- urethane polyfunctional acrylate oligomer 3 to 15 functional
- UV curable resins are used in combination with solvent-drying resins (such as thermoplastic resins that can form a film by simply drying the solvent added to adjust the solid content during coating). You can also. By using the solvent-drying resin in combination, film defects on the coated surface can be effectively prevented.
- solvent-drying resin that can be used in combination with the ultraviolet curable resin is not particularly limited, and a general thermoplastic resin can be used.
- the photopolymerization initiator is not particularly limited and known ones can be used.
- the photopolymerization initiator acetophenones, benzophenones, Michler benzoylbenzoate, ⁇ -amyloxime ester, thioxanthones
- examples include propiophenones, benzyls, benzoins, and acylphosphine oxides.
- it is preferable to use a mixture of photosensitizers and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine and the like.
- the photopolymerization initiator it is preferable to use acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, etc. alone or in combination when the ultraviolet curable resin is a resin system having a radical polymerizable unsaturated group. .
- the ultraviolet curable resin is a resin system having a cationic polymerizable functional group
- photopolymerization initiator in the case of an ultraviolet curable resin having a radical polymerizable unsaturated group, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name: IRGACURE 184, manufactured by BASF Japan Ltd.) It is preferable for reasons of compatibility and little yellowing.
- the content of the photopolymerization initiator in the hard coat layer forming composition is preferably in the range of 1.0 to 10 parts by mass with respect to 100 parts by mass of the ultraviolet curable resin. If the addition amount is 1.0 part by mass or more, the hardness of the hard coat layer can be set to a desired condition, and if it is 10 parts by mass or less, the ionizing radiation reaches the deep part of the coated film and is internally cured. Is preferable in that the desired pencil hardness of the surface of the hard coat layer can be obtained.
- the more preferable lower limit of the content of the photopolymerization initiator is 2.0 parts by mass, and the more preferable upper limit is 8.0 parts by mass.
- the content of the photopolymerization initiator is in this range, a hardness distribution does not occur in the film thickness direction, and the hard coat layer tends to have a uniform hardness.
- the composition for forming a hard coat layer may contain a solvent.
- a solvent it can select suitably and can be used according to the kind and solubility of the ultraviolet curable resin component to be used.
- solvents ketones (for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol, etc.), ethers (for example, dioxane, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.), aliphatic Hydrocarbons (eg, hexane, etc.), alicyclic hydrocarbons (eg, cyclohexane, etc.), aromatic hydrocarbons (eg, toluene, xylene, etc.), halogenated carbons (eg, dichloromethane, dichloroethane, etc.), Esters (eg, methyl acetate,
- methyl ethyl ketone methyl isobutyl ketone, cyclohexanone, or a mixture thereof is contained in the ketone solvent because of excellent compatibility with an ultraviolet curable resin and coating properties.
- the hard coat layer-forming composition increases the hardness of the hard coat layer, suppresses curing shrinkage, prevents blocking, controls the refractive index, imparts antiglare properties, the surface of particles and hard coat layer
- conventionally known organic fine particles, inorganic fine particles, dispersants, surfactants, antistatic agents, silane coupling agents, thickeners, anti-coloring agents, colorants (pigments, Dyes), antifoaming agents, leveling agents, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, surface modifiers, and the like may be added.
- the composition for forming a hard coat layer may contain a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine and the like.
- the method for preparing the composition for forming a hard coat layer is not particularly limited as long as each component can be uniformly mixed.
- each component is used using a known apparatus such as a paint shaker, a bead mill, a kneader, or a mixer.
- a paint shaker such as a paint shaker, a bead mill, a kneader, or a mixer.
- the method for applying the hard coat layer forming composition onto the first protective film is not particularly limited, and examples thereof include spin coating, dipping, spraying, die coating, bar coating, and rolls.
- Well-known wet coating methods such as a coater method, a meniscus coater method, a flexographic printing method, a screen printing method, and a pea coater method can be exemplified.
- the retardation Ro in the in-plane direction of the first protective film may be 350 nm or less. Further, the retardation Rt in the thickness direction of the first protective film may be 350 nm or less.
- a film containing an acrylic resin including an acrylic-styrene polymer
- the retardation Ro in the in-plane direction of the first protective film may be 8000 nm or more. Further, the retardation Ro in the thickness direction of the first protective film may be 8000 nm or more. In this case, for example, a film containing a polyethylene terephthalate resin can be used as the first protective film.
- the first protective film desirably contains a polyethylene terephthalate resin or an acrylic resin.
- the first protective film having a moisture permeability of 200 g / m 2 ⁇ day or less can be reliably realized.
- the thickness of the first protective film is desirably 10 ⁇ m or more and 40 ⁇ m or less. Use of the thin first protective film can contribute to the realization of a thin polarizing plate.
- the polarizing plate of this embodiment has a configuration in which the first protective film and the second protective film described above are bonded to both surfaces of a polarizer using an ultraviolet curable adhesive or an aqueous adhesive.
- the protective film for the polarizing plate is preferably provided with an antiglare layer or a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer and the like.
- the polarizer which is the main component of the polarizing plate, is an element that passes only light having a plane of polarization in a certain direction, and a typical known polarizer is a polyvinyl alcohol polarizing film.
- the polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.
- polarizer a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used.
- the thickness of the polarizer is preferably 2 to 30 ⁇ m, particularly preferably 2 to 15 ⁇ m.
- the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%
- the degree of polymerization is 2000 to 4000
- the degree of saponification is 99.0 to 99.99 mol%.
- the ethylene-modified polyvinyl alcohol is also preferably used.
- an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.
- a polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has little color unevenness, and is particularly preferably used for a large liquid crystal display device.
- the polarizing plate of this embodiment can be produced by a general method. Specifically, the surface of the first protective film facing the polarizer is appropriately surface-treated, and an ultraviolet curable adhesive or water-based adhesive, which will be described later, is applied to one surface of the polarizer produced by immersion and stretching in an iodine solution. Paste together using an agent. And a 2nd protective film is bonded on the other surface of a polarizer.
- the direction of bonding with the polarizer is preferably bonded so that, for example, the absorption axis of the polarizer and the slow axis of each protective film are orthogonal to each other.
- the protective film and the polarizer are bonded by an ultraviolet curable adhesive.
- an ultraviolet curable adhesive to the bonding between the protective film and the polarizer, a polarizing plate having high strength and excellent flatness can be obtained even in a thin film.
- UV curable adhesive composition for polarizing plates a photo radical polymerization composition using photo radical polymerization, a photo cation polymerization composition using photo cation polymerization, and photo radical polymerization and photo cation polymerization are used in combination.
- Hybrid type compositions are known.
- the radical photopolymerizable composition includes a radically polymerizable compound containing a polar group such as a hydroxy group and a carboxy group described in JP-A-2008-009329 and a radically polymerizable compound not containing a polar group at a specific ratio.
- Composition) and the like are known.
- the radical polymerizable compound is preferably a compound having a radical polymerizable ethylenically unsaturated bond.
- the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group.
- Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound.
- (Meth) acrylamide means acrylamide or methacrylamide.
- cationic photopolymerization type composition as disclosed in JP2011-08234A, ( ⁇ ) a cationic polymerizable compound, ( ⁇ ) a cationic photopolymerization initiator, and ( ⁇ ) a wavelength longer than 380 nm.
- an ultraviolet curable adhesive composition containing each component of a photosensitizer exhibiting maximum absorption in the light of ( ⁇ ) and a naphthalene-based photosensitization aid.
- other ultraviolet curable adhesives may be used.
- Pre-processing process is a process of performing an easily bonding process to the adhesive surface with the polarizer of a protective film.
- Examples of the easy adhesion treatment include corona treatment and plasma treatment.
- the ultraviolet curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the protective film for the polarizing plate.
- the application method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.
- coating an ultraviolet curable adhesive between a polarizer and a protective film the method of pressurizing with a roller etc. and spreading uniformly can also be utilized.
- an uncured UV curable adhesive is irradiated with UV rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound, acrylamide).
- a cationic polymerizable compound for example, an epoxy compound or an oxetane compound
- a radical polymerizable compound for example, an acrylate compound, acrylamide.
- the ultraviolet curable adhesive layer containing the compound and the like is cured, and the polarizer and the protective film are bonded to each other through the ultraviolet curable adhesive.
- ultraviolet rays are irradiated on both sides of the polarizer in a state where the protective films are superimposed on each other via an ultraviolet curable adhesive. It is advantageous to cure the curable adhesive simultaneously.
- any appropriate conditions can be adopted as the ultraviolet irradiation conditions as long as the ultraviolet curable adhesive can be cured.
- the dose of ultraviolet rays in the range of 50 ⁇ 1500mJ / cm 2 in accumulated light quantity, and even more preferably in the range of 100 ⁇ 500mJ / cm 2.
- the line speed depends on the curing time of the adhesive, but is preferably in the range of 1 to 500 m / min, more preferably in the range of 5 to 300 m / min, and still more preferably in the range of 10 to The range is 100 m / min.
- productivity can be ensured, or damage to the protective film can be suppressed, and a polarizing plate excellent in durability can be produced.
- the line speed is 500 m / min or less, the ultraviolet curable adhesive is sufficiently cured, and an ultraviolet curable adhesive layer having a desired hardness and excellent adhesiveness can be formed.
- thermoplastic resin is bonded to the polarizer using a water glue or an ultraviolet curable adhesive on the surface opposite to the surface on which the protective film of the polarizer is bonded.
- the surface to be bonded to the polarizer is preferably saponified and bonded with a polyvinyl alcohol water paste.
- the polarizing plate of this embodiment can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB, etc., but preferably IPS type liquid crystal display devices. It is.
- the liquid crystal display device normally uses two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side.
- the polarizing plate of the present embodiment is used as both the polarizing plate on the viewing side and the backlight side. It is preferable to use it as a polarizing plate on one side.
- the direction of bonding of the polarizing plate in the IPS liquid crystal display device can be performed with reference to JP-A-2005-234431.
- the liquid crystal cell used in this embodiment includes a liquid crystal layer and a pair of substrates (glass substrates) that sandwich the liquid crystal layer, and the pair of substrates has a thickness in the range of 0.3 to 0.7 mm.
- a substrate is preferable from the viewpoint of reducing the thickness and weight of the liquid crystal display device.
- the polarizing plate of this embodiment can make it difficult to produce panel bend even if the glass substrate which comprises a liquid crystal cell is thinned.
- Examples of the material constituting the glass substrate that can be used in the liquid crystal cell include soda lime glass and silicate glass, and silicate glass is preferable. Specifically, silica glass or borosilicate is used. An acid glass is more preferable.
- the glass constituting the glass substrate is preferably a non-alkali glass that does not substantially contain an alkali component, specifically, a glass having an alkali component content of 1000 ppm or less.
- the content of the alkali component in the glass substrate is preferably 500 ppm or less, and more preferably 300 ppm or less.
- substitution of cations occurs on the film surface, and soda blowing phenomenon tends to occur. Thereby, the density of the film surface layer is likely to decrease, and the glass substrate is easily damaged.
- the thickness of the glass substrate of the liquid crystal cell constituting the liquid crystal display device is preferably within the range of 0.3 to 0.7 mm. Such a thickness is preferable in that it can contribute to the thinning of the liquid crystal display device.
- the glass substrate can be formed by a known method such as a float method, a down draw method, an overflow down draw method or the like.
- the overflow downdraw method is preferable because the surface of the glass substrate does not come into contact with the molding member during molding and the surface of the resulting glass substrate is hardly damaged.
- Such a glass substrate can also be obtained as a commercial product.
- non-alkali glass AN100 (thickness 500 ⁇ m) manufactured by Asahi Glass Co., Ltd.
- glass substrate EAGLE XG (r) Slim (thickness manufactured by Corning) 300 ⁇ m, 400 ⁇ m, etc.)
- glass substrates (thickness 100 to 200 ⁇ m) manufactured by Nippon Electric Glass Co., Ltd. can be mentioned.
- the polarizing plate and the glass substrate constituting the liquid crystal cell are bonded via an adhesive layer.
- the adhesive layer it is possible to apply a double-sided tape, for example, a 25 ⁇ m-thick double-sided tape (substrate-less tape MO-3005C) manufactured by Lintec Corporation, or a composition used for forming an actinic ray curable resin layer. it can.
- panel bend is suppressed even in the case of a large-screen liquid crystal display device with a screen size of 30 or more, and it is excellent in visibility such as display unevenness and front contrast, and is thin and lightweight.
- a liquid crystal display device can be obtained.
- a cellulose ester resin was synthesized by the method described in JP-A-10-45804 and JP-A-8-231761, and the degree of substitution was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the substitution degree of the acyl group was adjusted by adjusting the amount of acetic acid. Moreover, it age
- TAC triacetyl cellulose
- polyester diol A A dibasic acid and glycol were subjected to a dehydration condensation reaction to prepare polyester diol A which is a hydroxyl group at both ends of the main chain. At this time, adipic acid was used as the dibasic acid, and ethylene glycol was used as the glycol.
- adipic acid was used as the dibasic acid
- ethylene glycol was used as the glycol.
- polyester diol B A polyester diol B in which dicarboxylic acid and glycol were subjected to dehydration condensation reaction to seal both ends of the main chain with an acyl group was prepared.
- dicarboxylic acid a mixture of terephthalic acid (45 mol%), phthalic acid (5 mol%), adipic acid (20 mol%), and succinic acid (30 mol%) in the above proportion is used.
- Dope composition Cellulose ester resin CA1 100 parts by weight Polyesterdiol A 20 parts by weight Ultraviolet absorber (Tinuvine 928 having the structure shown in Chemical formula 12 (manufactured by BASF Japan)) 2.4 parts by mass Methylene chloride 394.0 parts by mass Methanol 59.0 parts by mass
- Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 89 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion.
- Fine particle additive solution Based on the following composition, the fine particle dispersion was slowly added to a dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution. 99 parts by mass of methylene chloride 5 parts by mass of fine particle dispersion
- dope composition Cellulose ester resin CA1 100 parts by weight Polyesterdiol A 20 parts by weight Ultraviolet absorber (Tinuvine 928 having a structure shown in Chemical formula 12 (BASF Japan) 2.4 parts by mass Fine particle additive solution 0.078 parts by mass Methylene chloride 394.0 parts by mass Methanol 59.0 parts by mass
- Second protective film 2-1> From the casting die of the band casting machine, using the core layer forming C01 and the skin layer forming dope solution C02 prepared above, a film laminated in the order of skin layer / core layer / skin layer is obtained. Each dope solution was co-cast on the traveling casting band (support) (simultaneous multilayer co-casting). At this time, the casting amount of each dope solution was adjusted so that each layer of the stretched film had the thickness shown in Table 1, and a casting film was formed on the casting band. The same dope solution C02 for forming a skin layer was used as the dope for forming the two skin layers sandwiching the core layer.
- the cast film was peeled off from the cast band, the solvent was evaporated at 35 ° C., and the film was dried at a drying temperature of 135 ° C. while being stretched 1.25 times in the width direction by tenter stretching.
- the residual solvent amount at the start of stretching by zone stretching was 20.0%, and the residual solvent amount at the start of stretching by tenter was 8.0%.
- a relaxation treatment was performed at 130 ° C. for 5 minutes, and then drying was completed while conveying a drying zone at 120 ° C. and 140 ° C. with a number of rollers.
- the obtained film was slit to a width of 1.5 m, a knurling process having a width of 10 mm and a height of 5 ⁇ m was applied to both ends of the film, and then wound on a core to form a second protective film 2-1 (three-layer laminated film).
- the second protective film 2-1 was prepared in such a manner that each additive (polyester diol, ultraviolet absorber) was added to the dope solution so as to have the composition shown in Table 1, or a film was formed without the addition.
- second protective films 2-2 to 2-5 (3-layer laminated film) were formed.
- the second protective film 2-2 is the same as the second protective film 2-1.
- Second protective film 2-6 Using only the dope solution C02 for skin layer formation, the addition amount of the fine particle additive solution is changed as shown in Table 1, and the dope solution is cast so that the film thickness after film formation becomes the value shown in Table 1.
- a second protective film 2-6 (single layer film) was formed in the same manner as the second protective film 2-1, except that the film was formed.
- the retardation values Ro ⁇ Rt of the second protective films 2-1 to 2-6 produced as described above were measured as follows. That is, using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics), a three-dimensional refractive index measurement was performed at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. From the refractive indexes nx, ny, and nz, the retardation values Ro ⁇ Rt of the second protective films 2-1 to 2-6 were calculated according to the above formula.
- Table 1 shows the configuration and characteristics of the second protective film.
- the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC in 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and further 15 minutes later, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.
- polyester resin A polyethylene terephthalate resin A
- the obtained polyester resin A had an intrinsic viscosity of 0.62 cm 3 / g and contained substantially no inert particles and internally precipitated particles.
- the transesterification and polycondensation reactions are carried out by conventional methods.
- the dicarboxylic acid component (based on the total dicarboxylic acid component), 46 mol% of terephthalic acid, 46 mol% of isophthalic acid, and 8 mol% of sodium 5-sulfonatoisophthalate was used to prepare a water-dispersible sulfonic acid metal base-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as the glycol component (relative to the entire glycol component).
- PET film (Preparation of PET film)
- the prepared polyester resin A is dried by a conventional method, supplied to an extruder, melted at 285 ° C., and this polymer is filtered with a filter material of stainless sintered body (nominal filtration accuracy of 10 ⁇ m particles 95% cut). After extruding in a sheet form, it was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method and cooled and solidified to produce an unstretched polyester film (PET film).
- PET film unstretched polyester film
- the unstretched film on which this adhesion improving layer was formed was guided to a tenter stretching machine, and was stretched four times in the width direction in a heating zone at a temperature of 125 ° C. while holding the end of the film with a clip.
- First protective film 1-1) was produced.
- the polymer solution continuously discharged from the polymerization reactor is supplied to a vent type screw type extruder having a reduced pressure of 2.7 to 4.0 kPa to remove volatile matter, and the pellet-shaped copolymer A1 is removed.
- the constituent ratio of the monomer unit in the copolymer A1 was 90 mol% for the styrene monomer, 10 mol% for the acrylic acid monomer, and the weight average molecular weight was 300,000.
- Dope 1 Composition of dope 1
- Copolymer A1 styrene: 90 mol%, acrylic acid: 10 mol%, weight average molecular weight: 300,000
- Fine particles R812 manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size 8 nm
- Methylene chloride 150 parts by mass Ethanol 5 parts by mass
- the prepared dope 1 was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus.
- the solvent was evaporated on the stainless steel band support until the residual solvent amount reached 50%, and the obtained film-like material was peeled off from the stainless steel band support with a peeling tension of 162 N / m.
- the peeled film-like product was dried at a drying temperature of 135 ° C. while evaporating the solvent at 35 ° C. and stretching it 1.25 times in the width direction by tenter stretching.
- the residual solvent amount at the start of stretching by zone stretching was 20.0%, and the residual solvent amount at the start of stretching by tenter was 8.0%.
- the obtained film was slit to a width of 1.5 m, subjected to a knurling process with a width of 10 mm and a height of 5 ⁇ m at both ends of the film, and then wound around a core to produce an acrylic film (first protective film 1-2). .
- the produced acrylic film had a thickness of 40 ⁇ m and a winding length of 4000 m.
- a polarizing plate 101 was produced according to the following method.
- ⁇ Preparation of Polarizing Plate 101> 1 Production of Polarizer Dyeing treatment by immersing a long polyvinyl alcohol film having a thickness of 60 ⁇ m in a dyeing bath (30 ° C.) containing iodine and potassium iodide while continuously conveying the polyvinyl alcohol film through a guide roll. And 2.5 times the stretching treatment, and then, in an acidic bath (60 ° C.) to which boric acid and potassium iodide are added, a total of 5 times the stretching treatment and the crosslinking treatment are performed, and the obtained thickness A 12 ⁇ m iodine-PVA polarizer was dried in a dryer at 50 ° C. for 30 minutes to obtain a polarizer with a moisture content of 4.9%.
- UV curable adhesive B The following components were mixed to prepare a liquid UV curable adhesive.
- the prepared UV curable adhesive B was thickened by a coating apparatus equipped with a chamber doctor. Coating was performed at 3 ⁇ m.
- the ultraviolet curable adhesive B was similarly applied to a thickness of 3 ⁇ m.
- the first protective film 1-1 is applied to one side of the polarizer prepared above.
- the second protective film 2-1 was bonded to the other surface with a bonding roll through the coating surface of the ultraviolet curable adhesive B.
- the metal halide lamp is irradiated from the first protective film 1-1 side so that the integrated light quantity at a wavelength of 280 to 320 nm is 320 mJ / cm 2 , thereby curing the adhesive on both sides.
- a polarizing plate 101 was obtained.
- the liquid crystal display device 201 was produced according to the following method using the polarizing plate 101 produced above.
- liquid crystal display device 201 As the liquid crystal cell, an IPS liquid crystal cell having two glass substrates having a thickness of 0.5 mm and a liquid crystal layer disposed therebetween was prepared. Then, the pair of polarizing plates 101 and 101 produced as described above were bonded to each other through the adhesive layer so that the second protective film was on the liquid crystal cell side to obtain a liquid crystal display device 201. The bonding was performed such that the absorption axis of the polarizer of the polarizing plate on the viewing side and the absorption axis of the polarizer of the polarizing plate on the backlight side were orthogonal to each other. In the same manner, liquid crystal display devices 202 to 206 were manufactured using polarizing plates 102 to 106.
- Each of the second protective films 2-1 to 2-6 produced above was cut into A4 size (210 mm ⁇ 297 mm) and stored for 1000 hours in a high-temperature and high-humidity thermo-machine with a temperature of 60 ° C. and a humidity of 90% RH.
- a wet heat treatment sample was prepared.
- the wet-heat treated film was conditioned for 24 hours under conditions of a temperature of 23 ° C. and a relative humidity of 55% RH.
- Table 2 shows the results of the above evaluation.
- the second protective film constituting the polarizing plate contains polyester diol A in which both ends of the main chain are hydroxyl groups, the second protective film has a configuration containing an ultraviolet absorber. Even if it exists, compatibility with a ultraviolet absorber and cellulose-ester resin can be improved at the time of film forming, and generation
- Examples 1 and 2 fine particles are contained only in the skin layer of the second protective film.
- the second protective film includes the ultraviolet absorber, the aggregation of the fine particles and the ultraviolet absorber occurs only in the skin layer when the second protective film is formed. For this reason, it is considered that haze deterioration in the entire film can be suppressed, and deterioration in durability of the second protective film can be suppressed.
- Example 1 the evaluation of bend unevenness and durability is better in Example 1 in which the first protective film is a PET film than in Example 2 in which the first protective film is an acrylic film.
- the PET film has a lower moisture permeability than the acrylic film and can further suppress the absorption of moisture. Therefore, it is considered that the PET film contributed to the suppression of bend unevenness and the durability.
- Comparative Example 1 since the second protective film does not contain an ultraviolet absorber, it is considered that the second protective film is deteriorated by ultraviolet rays and the durability is deteriorated.
- the polyester diol added to the second protective film is not a polyester diol in which both ends of the main chain are hydroxyl groups, and in Comparative Example 3, the polyester diol itself is not added. It is considered that the compatibility between the resin and the resin could not be improved, and as a result, cracks occurred in the formed film, resulting in bend unevenness.
- Comparative Example 4 since the second film is composed of a single layer film and the fine particles are dispersed throughout the film, the fine particles and the ultraviolet absorber are aggregated over the entire film, and the haze of the entire film is increased. It is thought that it deteriorated and durability deteriorated.
- the polarizing plate and the liquid crystal display device of the present embodiment described above can be expressed as follows.
- a polarizing plate in which a first protective film, a polarizer, and a second protective film are laminated in this order,
- (I) Ro (nx ⁇ ny) ⁇ d
- Rt ((nx + ny) / 2 ⁇ nz) ⁇ d
- nx is the refractive index in the slow axis direction in the film plane
- ny is the refractive index in the fast axis direction in the film plane
- nz is the refractive index in the thickness direction of the film (refractive index is 23 ° C., 55%) (Measured at a wavelength of 590 nm in an RH environment)
- the polarizing plate according to any one of 1 to 5, An IPS type liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates, The liquid crystal display, wherein the polarizing plate is disposed on the viewing side with respect to the liquid crystal cell, and the second protective film is disposed on the liquid crystal cell side with respect to the polarizer. apparatus.
- the polarizing plate of the present invention can be used for, for example, an IPS liquid crystal display device.
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Abstract
Description
前記第2の保護フィルムにおいて、下記式(i)で定義されるフィルム面内方向のリタデーション値Ro(nm)および下記式(ii)で定義されるフィルムの厚み方向のリタデーション値Rt(nm)が、下記式(iii)および(iv)で規定する条件を満たし、
(i)Ro=(nx-ny)×d
(ii)Rt=((nx+ny)/2-nz)×d
(式中、nxはフィルム面内の遅相軸方向の屈折率、nyはフィルム面内の進相軸方向の屈折率、nzはフィルムの厚み方向の屈折率(屈折率は23℃、55%RHの環境下、波長590nmで測定)、dはフィルムの厚さ(nm)を表す。)
(iii)0nm≦Ro≦10nm
(iv)|Rt|≦25nm
前記第1の保護フィルムおよび前記第2の保護フィルムのうち、前記第2の保護フィルムのみが、紫外線吸収剤を含み、
前記第2の保護フィルムは、主鎖の両末端が水酸基であるポリエステルジオールを含み、
前記第2の保護フィルムは、コア層と、前記コア層の表面側および裏面側に位置し、微粒子を含有する2つのスキン層とを含む積層フィルムである。
上記の偏光板と、
一対の基板で液晶層を挟持したIPS型の液晶セルとを含み、
前記偏光板は、前記液晶セルに対して視認側に配置され、かつ、前記偏光子に対して前記第2の保護フィルムが前記液晶セル側となるように配置される。
(i)Ro=(nx-ny)×d
(ii)Rt=((nx+ny)/2-nz)×d
(式中、nxはフィルム面内の遅相軸方向の屈折率、nyはフィルム面内の進相軸方向の屈折率、nzはフィルムの厚み方向の屈折率(屈折率は23℃、55%RHの環境下、波長590nmで測定)、dはフィルムの厚さ(nm)を表す。)
(iii)0nm≦Ro≦10nm
(iv)|Rt|≦25nm
前記第1の保護フィルムおよび前記第2の保護フィルムのうち、前記第2の保護フィルムのみが、紫外線吸収剤を含み、
前記第2の保護フィルムは、主鎖の両末端が水酸基であるポリエステルジオールを含み、
前記第2の保護フィルムは、コア層と、前記コア層の表面側および裏面側に位置し、微粒子を含有する2つのスキン層とを含む積層フィルムである。
以下、本実施形態の液晶表示装置の具体的な構成について説明する。図1は、本実施形態に係るIPS型の液晶表示装置1の概略の構成を示す断面図である。液晶表示装置1は、液晶表示パネル2およびバックライト3を備えている。バックライト3は、液晶表示パネル2を照明するための光源である。
次に、視認側の偏光板の第2の保護フィルムについて説明する。なお、以下で示す第2の保護フィルムの構成は、バックライト側の偏光板の第3の保護フィルムにも適用可能である。ただし、第2の保護フィルムに含まれる紫外線吸収剤は、第3の保護フィルムに含まれていてもよいし、含まれていなくてもよい。
(i)Ro=(nx-ny)×d
(ii)Rt={(nx+ny)/2-nz}×d
(式中、nxはフィルム面内の遅相軸方向の屈折率、nyはフィルム面内の進相軸方向(遅相軸に垂直な方向)の屈折率、nzはフィルムの厚み方向の屈折率(屈折率は23℃、55%RHの環境下、波長590nmで測定)、dはフィルムの厚さ(nm)を表す。)
(iii)0nm≦Ro≦10nm
(iv)|Rt|≦25nm
本実施形態の第2の保護フィルムは、セルロースエステル樹脂であるセルロースアシレートを含むコア層と、コア層の表面側にセルロースアシレートを含む第1のスキン層と、コア層の裏面側にセルロースアシレートを含む第2のスキン層とを有する。なお、本実施形態において、「コア層」とは最も膜厚が厚い層のことをいい、「スキン層」とは、コア層よりも膜厚が薄く、コア層の表裏に接している層のことを言う。
第2の保護フィルム全体の膜厚は、3μm以上50μm以下であることが好ましく、5μm以上47μm以下であることがより好ましく、7μm以上45μm以下であることが更に好ましい。膜厚を3μm以上とすることにより、フィルムとしての強度を確保できるので好ましく、また膜厚を50μm以下とすることにより、湿度変化に対応しやすく、光学特性を維持しやすくなる。
第2の保護フィルムのコア層およびスキン層に用いられるセルロースアシレートは、特に限定されない。セルロースアシレートの原料としては、綿花リンタや木材パルプ(広葉樹パルプ,針葉樹パルプ)などがあり、何れの原料から得られるセルロースアシレートでも使用でき、場合により複数種の原料から得られるセルロースアシレートを混合して使用してもよい。
〈ポリエステルジオール〉
第2の保護フィルムは、ポリエステルジオールを添加剤として含むことが望ましい。該ポリエステルジオールは、セルロースアシレートドープまたはセルロースアシレートフィルムと相溶する添加剤が所望の特性を発揮するように、その構造、分子量、添加量が適宜選択される。
第2の保護フィルムには、微粒子(マット剤)を添加することができる。マット剤としては、ハンドリングの際に傷が付いたり、搬送性が悪化することを防止する機能を呈する素材であれば特に限定されず、無機化合物または有機化合物のマット剤を使用することができる。
第2の保護フィルムは、セルロースアシレートと共に、リタデーション低下剤を含む構成が好ましい。
第2の保護フィルムは、リタデーション低下剤として、数平均分子量が500以上、30000以下であるアクリルポリマーを含有してもよい。このようなアクリルポリマーとしては、国際公開WO08/044463号公報の段落〔0059〕~〔0093〕に記載のものが好ましく用いられる。
第2の保護フィルムは、リタデーション低下剤として、下記一般式(B1)または(B2)で表されるポリエステルを含有してもよい。これは、炭素数2~12の2価のアルコールGと炭素数2~12の2塩基酸、炭素数1~12のモノカルボン酸B1、もしくは炭素数1~12のモノアルコールであるB2から得られたポリエステルある。
B1-(G-A-)mG-B1
上記一般式(B1)において、B1は炭素数1~12のモノカルボン酸を表し、Gは炭素数2~12の2価のアルコールを表し、Aは炭素数2~12の2塩基酸を表す。B1、G、Aはいずれも芳香環の比率が少ないか、含まないことが特に好ましい。mは繰り返し数を表す。
B2-(A-G-)nA-B2
上記一般式(B2)において、B2は炭素数1~12のモノアルコールを表し、Gは炭素数2~12の2価のアルコールを表し、Aは炭素数2~12の2塩基酸を表す。B2、G、Aはいずれも芳香環の比率が少ないか、含まないことが特に好ましい。nは繰り返し数を表す。
第2の保護フィルムは、必要に応じて可塑剤を含有することができる。可塑剤は特に限定されないが、好ましくは、多価カルボン酸エステル系可塑剤、グリコレート系可塑剤、フタル酸エステル系可塑剤、脂肪酸エステル系可塑剤および多価アルコールエステル系可塑剤、ポリエステル系可塑剤、アクリル系可塑剤等から選択される。なお、これらの可塑剤がリタデーション低下剤として作用する場合もある。
R2(COOH)m(OH)n
上記一般式(C)において、R2は(m+n)価の有機基、mは2以上の正の整数、nは0以上の整数、COOH基はカルボキシ基、OH基はアルコール性またはフェノール性ヒドロキシ基を表す。
B-(G-A)n-G-B
上記一般式(D)において、Bはベンゼンモノカルボン酸残基、Gは炭素数2~12のアルキレングリコール残基または炭素数6~12のアリールグリコール残基または炭素数が4~12のオキシアルキレングリコール残基、Aは炭素数4~12のアルキレンジカルボン酸残基または炭素数6~12のアリールジカルボン酸残基を表し、nは1以上の整数を表す。
反応容器にフタル酸410部、安息香酸610部、ジプロピレングリコール737部、及び触媒としてテトライソプロピルチタネート0.40部を一括して仕込み窒素気流中で攪拌下、還流凝縮器を付して過剰の1価アルコールを還流させながら、酸価が2以下になるまで130~250℃で加熱を続け生成する水を連続的に除去した。次いで200~230℃で1.33×104Pa~最終的に4×102Pa以下の減圧下、留出分を除去し、この後濾過して次の性状を有する芳香族末端エステル系可塑剤を得た。
粘度(25℃、mPa・s);43400
酸価 ;0.2
反応容器に、フタル酸410部、安息香酸610部、エチレングリコール341部、及び触媒としてテトライソプロピルチタネート0.35部を用いる以外はサンプルNo.1と全く同様にして次の性状を有する芳香族末端エステルを得た。
粘度(25℃、mPa・s);31000
酸価 ;0.1
反応容器に、フタル酸410部、安息香酸610部、1,2-プロパンジオール418部、及び触媒としてテトライソプロピルチタネート0.35部を用いる以外はサンプルNo.1と全く同様にして次の性状を有する芳香族末端エステルを得た。
粘度(25℃、mPa・s);38000
酸価 ;0.05
反応容器に、フタル酸410部、安息香酸610部、1,3-プロパンジオール418部、及び触媒としてテトライソプロピルチタネート0.35部を用いる以外はサンプルNo.1と全く同様にして次の性状を有する芳香族末端エステルを得た。
粘度(25℃、mPa・s);37000
酸価 ;0.05
第2の保護フィルムは、紫外線吸収機能を有する紫外線吸収剤を含有することが望ましい。上記紫外線吸収剤は、380nmでの光透過率を50%未満とするための最も有効な手段である。紫外線吸収剤は、積層フィルムである第2の保護フィルムの少なくともいずれかの層に含まれていることが望ましいが、コア層および2つのスキン層の両方に含まれていることが望ましい。
UV-2:2-(2′-ヒドロキシ-3′,5′-ジ-tert-ブチルフェニル)ベンゾトリアゾール
UV-3:2-(2′-ヒドロキシ-3′-tert-ブチル-5′-メチルフェニル)ベンゾトリアゾール
UV-4:2-(2′-ヒドロキシ-3′,5′-ジ-tert-ブチルフェニル)-5-クロロベンゾトリアゾール
UV-5:2-(2′-ヒドロキシ-3′-(3″,4″,5″,6″-テトラヒドロフタルイミドメチル)-5′-メチルフェニル)ベンゾトリアゾール
UV-6:2,2-メチレンビス(4-(1,1,3,3-テトラメチルブチル)-6-(2H-ベンゾトリアゾール-2-イル)フェノール)
UV-7:2-(2′-ヒドロキシ-3′-tert-ブチル-5′-メチルフェニル)-5-クロロベンゾトリアゾール
UV-8:2-(2H-ベンゾトリアゾール-2-イル)-6-(直鎖及び側鎖ドデシル)-4-メチルフェノール(TINUVIN171)
UV-9:オクチル-3-〔3-tert-ブチル-4-ヒドロキシ-5-(クロロ-2H-ベンゾトリアゾール-2-イル)フェニル〕プロピオネートと2-エチルヘキシル-3-〔3-tert-ブチル-4-ヒドロキシ-5-(5-クロロ-2H-ベンゾトリアゾール-2-イル)フェニル〕プロピオネートの混合物(TINUVIN109)
UV-11:2,2′-ジヒドロキシ-4-メトキシベンゾフェノン
UV-12:2-ヒドロキシ-4-メトキシ-5-スルホベンゾフェノン
UV-13:ビス(2-メトキシ-4-ヒドロキシ-5-ベンゾイルフェニルメタン)
本実施形態の第2の保護フィルムは、セルロースエステル樹脂を含むコア層形成用ドープと、セルロースエステル樹脂を含む第1スキン層形成用ドープと、セルロースエステル樹脂を含む第2スキン層形成用ドープを、支持体上に共流延することにより製膜することができる。このとき、上記の3種のドープは、支持体上に同時または逐次で多層流延することができる。本実施形態では、共流延したドープを乾燥してフィルムとし、上記フィルムを支持体から剥離し、剥離後のフィルムを延伸してもよい。
本実施形態では、溶液流延製膜法によりセルロースアシレートを有機溶媒に溶解した溶液(ドープ)を用いて第2の保護フィルムを製造することができる。
調製したセルロースアシレート溶液(ドープ)から、溶液製膜法によりセルロースアシレテートフィルムを製造することができる。
ドラム又はベルト上で乾燥され、剥離されたフィルムの乾燥方法について述べる。ドラムやベルトが1周する直前の剥離位置で剥離されたフィルムは、千鳥状に配置されたロ-ル群に交互に通して搬送する方法や、剥離されたフィルムの両端をクリップ等で把持させて非接触的に搬送する方法などにより搬送される。乾燥は、搬送中のフィルム両面に所定の温度の風を当てる方法や、マイクロウエ-ブなどの加熱手段などを用いる方法によって行うことができる。急速な乾燥は、形成されるフィルムの平面性を損なう恐れがあるので、乾燥の初期段階では、溶媒が発泡しない程度の温度で乾燥し、乾燥が進んでから高温で乾燥を行うのが好ましい。
本実施形態においては、共流延したドープを乾燥させて支持体から剥離した後、フィルムを延伸することができる。
残留溶媒量(質量%)={(M-N)/N}×100
ここで、Mはフィルム(ウェブ)の任意時点での質量、NはMを測定したフィルムを110℃で3時間乾燥させた時の質量である。
次に、視認側の偏光板の第1の保護フィルムについて説明する。なお、以下で示す第1の保護フィルムの構成は、バックライト側の偏光板の第4の保護フィルムにも適用可能である。
第1の保護フィルムは、面内に超複屈折性を有し、波長380nmでの光透過率が50%以上であるポリエステルフィルムであってもよい。ここで、面内に超複屈折性を有するとは、面内方向のリタデーションRoが、8000nm以上であることを言う。第1の保護フィルムにおける波長380nmでの光透過率は、60~95%であることが望ましく、70~95%であることがより望ましく、80~95%であることがより一層望ましい。
以下に、延伸ポリエステルフィルムの製造方法の概要を説明する。
厚さムラ(%)=((dmax-dmin)/d)×100
本実施形態の第1の保護フィルムは、アクリル系樹脂を含むフィルム(アクリルフィルム)であってもよい。アクリル系樹脂には、メタクリル樹脂も含まれる。アクリルフィルムは、セルロースエステルフィルムと同様に、例えば溶液流延製膜法によって製造することができる。
本実施形態においては、第1の保護フィルムが、紫外線硬化樹脂層(以下、ハードコート層とも称する)を有する構成であることが好ましい。
第1の保護フィルムの面内方向のリタデーションRoは、350nm以下であってもよい。また、第1の保護フィルムの厚み方向のリタデーションRtは、350nm以下であってもよい。この場合、例えばアクリル樹脂(アクリル-スチレンポリマーを含む)を含有するフィルムを第1の保護フィルムとして用いることができる。
本実施形態の偏光板は、上述した第1の保護フィルムおよび第2の保護フィルムが、紫外線硬化型接着剤または水系接着剤を用いて、偏光子の両面に貼合されている構成である。上記偏光板が視認側の偏光板として用いられる場合、偏光板用の保護フィルムには、防眩層あるいはクリアハードコート層、反射防止層、帯電防止層、防汚層等を設けることが好ましい。
偏光板の主たる構成要素である偏光子は、一定方向の偏波面の光だけを通す素子であり、現在知られている代表的な偏光子は、ポリビニルアルコール系偏光フィルムである。ポリビニルアルコール系偏光フィルムには、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。
本実施形態の偏光板は、一般的な方法で作製することができる。具体的には、第1の保護フィルムの偏光子対向面側を適宜表面処理し、ヨウ素溶液中に浸漬延伸して作製した偏光子の一方の面に、後述する紫外線硬化型接着剤または水系接着剤を用いて貼り合わせる。そして、偏光子の他方の面に第2の保護フィルムを貼合する。
本実施形態の偏光板においては、保護フィルムと偏光子とが、紫外線硬化型接着剤により接着されていることが好ましい。保護フィルムと偏光子との貼合に紫外線硬化型接着剤を適用することにより、薄膜でも強度が高く、平面性に優れた偏光板を得ることができる。
偏光板用の紫外線硬化型接着剤組成物としては、光ラジカル重合を利用した光ラジカル重合型組成物、光カチオン重合を利用した光カチオン重合型組成物、並びに光ラジカル重合及び光カチオン重合を併用したハイブリッド型組成物が知られている。
前処理工程は、保護フィルムの偏光子との接着面に易接着処理を行う工程である。易接着処理としては、コロナ処理、プラズマ処理等が挙げられる。
紫外線硬化型接着剤の塗布工程としては、偏光子と偏光板用の保護フィルムとの接着面のうち少なくとも一方に、上記紫外線硬化型接着剤を塗布する。偏光子又は保護フィルムの表面に直接、紫外線硬化型接着剤を塗布する場合、その塗布方法に特段の限定はない。例えば、ドクターブレード、ワイヤーバー、ダイコーター、カンマコーター、グラビアコーター等、種々の湿式塗布方式が利用できる。また、偏光子と保護フィルムの間に、紫外線硬化型接着剤を塗布したのち、ローラー等で加圧して均一に押し広げる方法も利用できる。
上記の方法により紫外線硬化型接着剤を塗布した後は、貼合工程で処理される。この貼合工程では、例えば、先の塗布工程で偏光子の表面に紫外線硬化型接着剤を塗布した場合、そこにセルロース樹脂フィルムが重ね合わされる。また、第1又は第2の保護フィルムの表面に紫外線硬化型接着剤を塗布する方式の場合には、そこに偏光子が重ね合わされる。また、偏光子と保護フィルムの間に紫外線硬化型接着剤を流延させた場合は、その状態で偏光子と保護フィルムとが重ね合わされる。そして、通常は、この状態で両面の保護フィルム側から加圧ローラー等で挟んで加圧することになる。加圧ローラーの材質は、金属やゴム等を用いることが可能である。両面に配置される加圧ローラーは、同じ材質であってもよいし、異なる材質であってもよい。
硬化工程では、未硬化の紫外線硬化型接着剤に紫外線を照射して、カチオン重合性化合物(例えば、エポキシ化合物やオキセタン化合物)やラジカル重合性化合物(例えば、アクリレート系化合物、アクリルアミド系化合物等)を含む紫外線硬化型接着剤層を硬化させ、紫外線硬化型接着剤を介して重ね合わせた偏光子と保護フィルムを接着させる。偏光子の両面に保護フィルムを貼合する本実施形態の構成においては、偏光子の両面にそれぞれ紫外線硬化型接着剤を介して保護フィルムを重ね合わせた状態で、紫外線を照射し、両面の紫外線硬化型接着剤を同時に硬化させるのが有利である。
上記した偏光板を液晶表示装置に用いることによって、種々の視認性に優れた液晶表示装置を作製することができる。
以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。なお、実施例において「部」あるいは「%」の表示を用いるが、特に断りがない限り「質量部」あるいは「質量%」を表す。
<セルロースエステル樹脂の調製>
特開平10-45804号公報および特開平8-231761号公報に記載の方法で、セルロースエステル樹脂を合成し、その置換度を測定した。具体的には、触媒として硫酸(セルロース100質量部に対し7.8質量部)を添加し、アシル置換基の原料となるカルボン酸を添加し40℃でアシル化反応を行った。この時、酢酸の量を調整することでアシル基の置換度を調整した。また、アシル化後に40℃で熟成を行った。さらに、このセルロースアセテートの低分子量成分をアセトンで洗浄し除去した。これにより、セルロースエステル樹脂CA1(トリアセチルセルロース(TAC)、総アシル置換度:2.81)を得た。
(ポリエステルジオールAの調製)
二塩基酸とグリコールとを脱水縮合反応させ、主鎖の両末端に水酸基であるポリエステルジオールAを調製した。このとき、上記二塩基酸としては、アジピン酸を用い、上記グリコールとしては、エチレングリコールを用いた。得られたポリエステルジオールAの水酸基価を、JIS K 1557-1:2007に記載の無水酢酸法によって測定したところ、113mgKOH/gであった。
ジカルボン酸とグリコールとを脱水縮合反応させ、主鎖の両末端をアシル基で封止したポリエステルジオールBを調製した。このとき、上記ジカルボン酸としては、テレフタル酸(45モル%)、フタル酸(5モル%)、アジピン酸(20モル%)、コハク酸(30モル%)を上記の割合で混合したものを用い、上記グリコールとしては、エチレングリコールを用いた。ポリエステルジオールBの数平均分子量(Mn)を、GPCによって測定したところ、Mn=840であった。
下記の組成物をミキシングタンクに投入し、撹拌して、各成分を溶解し、コア層形成用ドープ溶液C01を調製した。
(ドープ組成)
セルロースエステル樹脂CA1 100質量部
ポリエステルジオールA 20質量部
紫外線吸収剤(化12で示した構造のチヌビン928(BASFジャパン社製)
2.4質量部
メチレンクロライド 394.0質量部
メタノール 59.0質量部
(微粒子分散液の調製)
微粒子(アエロジル R972V 日本アエロジル(株)製)11質量部
エタノール 89質量部
以上をディゾルバーで50分間攪拌混合した後、マントンゴーリンで分散を行って、微粒子分散液を得た。
以下の組成に基づいて、メチレンクロライドを入れた溶解タンクに充分攪拌しながら、上記微粒子分散液をゆっくりと添加した。さらに二次粒子の粒径が所定の大きさとなるようにアトライターにて分散を行った。これを日本精線(株)製のファインメットNFで濾過し、微粒子添加液を調製した。
メチレンクロライド 99質量部
微粒子分散液 5質量部
下記の組成物をミキシングタンクに投入し、撹拌して、各成分を溶解し、スキン層形成用ドープ溶液C02を調製した。
(ドープ組成)
セルロースエステル樹脂CA1 100質量部
ポリエステルジオールA 20質量部
紫外線吸収剤(化12で示した構造のチヌビン928(BASFジャパン社製)
2.4質量部
微粒子添加液 0.078質量部
メチレンクロライド 394.0質量部
メタノール 59.0質量部
上記で調製したコア層形成用C01およびスキン層形成用ドープ溶液C02を用い、スキン層/コア層/スキン層の順で積層されたフィルムが得られるように、バンド流延機の流延ダイから、走行する流延バンド(支持体)上に各ドープ溶液を共流延(同時多層共流延)した。このとき、延伸後のフィルムの各層が、表1で示した膜厚となるように、各ドープ溶液の流延量を調整し、流延バンド上に流延膜を形成した。なお、コア層を挟む2つのスキン層を形成するドープとしては、同じスキン層形成用ドープ溶液C02を用いた。
表1に示す組成となるように、各添加剤(ポリエステルジオール、紫外線吸収剤)をドープ溶液に添加し、または添加せずにフィルムを製膜した以外は、第2の保護フィルム2-1の製膜と同様にして、第2の保護フィルム2-2~2-5(3層積層フィルム)を製膜した。なお、第2の保護フィルム2-2は、第2の保護フィルム2-1と同じである。
スキン層形成用ドープ溶液C02のみを用い、微粒子添加液の添加量を表1のように変更し、製膜後のフィルムの膜厚が表1に示す値となるようにドープ溶液を流延してフィルムを製膜した以外は、第2の保護フィルム2-1の製膜と同様にして、第2の保護フィルム2-6(単層フィルム)を製膜した。
上記で作製した第2の保護フィルム2-1~2-6のリタデーション値Ro・Rtを以下のようにして測定した。すなわち、自動複屈折率計アクソスキャン(Axo Scan Mueller Matrix Polarimeter:アクソメトリックス社製)を用い、23℃・55%RHの環境下、590nmの波長において、三次元屈折率測定を行い、得られた屈折率nx、ny、nzから、前述の式により、第2の保護フィルム2-1~2-6のリタデーション値Ro・Rtを算出した。
<第1の保護フィルム1-1の製膜>
(ポリエステル樹脂Aの調製)
エステル化反応容器を昇温して、200℃で、テレフタル酸を86.4質量部及びエチレングリコールを64.6質量部投入し、加熱撹拌しながら、触媒として三酸化アンチモンを0.017質量部、酢酸マグネシウム4水和物を0.064質量部、トリエチルアミン0.16質量部を投入した。ゲージ圧が0.34MPa、温度が240℃の条件下で加圧エステル化反応を行った。
常法によりエステル交換反応及び重縮合反応を行い、ジカルボン酸成分として(ジカルボン酸成分全体に対して)テレフタル酸を46モル%、イソフタル酸を46モル%及び5-スルホナトイソフタル酸ナトリウム8モル%を用い、グリコール成分として(グリコール成分全体に対して)エチレングリコールを50モル%及びネオペンチルグリコールを50モル%の組成の水分散性スルホン酸金属塩基含有共重合ポリエステル樹脂を調製した。
上記調製したポリエステル樹脂Aを常法により乾燥して押出機に供給し、285℃で溶融し、このポリマーをステンレス焼結体の濾材(公称濾過精度10μm粒子95%カット)で濾過して、口金よりシート状にして押し出した後、静電印加キャスト法を用いて表面温度30℃のキャスティングドラムに巻きつけて冷却固化して、未延伸のポリエステルフィルム(PETフィルム)を作製した。
(アクリル系樹脂1(共重合体A1)の合成)
単量体として、スチレンを93.6質量部(90mol%)とアクリル酸7.2質量部(10mol%)と、エチルベンゼンを29.4質量部、2-エチルヘキサノールを3.3質量部の混合液に対し、2,2-ビス(4,4-ジターシャリーブチルパーオキサイド)プロパンを0.04質量部添加し、この重合液を、5.0Lの完全混合型反応器を有する重合装置に、1.67L/時で連続的に仕込んだ。この時、完全混合型反応器の温度は135℃に調整した。次いで、重合反応器より連続して排出される重合体溶液を2.7~4.0kPaに減圧されたベントタイプスクリュー式押出機に供給し、揮発分を除去してペレット状の共重合体A1を得た。共重合体A1における単量体単位の構成比率は、スチレン単量体が90mol%、アクリル酸単量体が10mol%であり、重量平均分子量は、30万であった。
(ドープ1の組成)
共重合体A1(スチレン:90mol%、アクリル酸:10mol%、重量平均分子量:30万)
100質量部
微粒子(日本アエロジル社製R812、シリカ粒子、平均粒径8nm)
0.30質量部
塩化メチレン 150質量部
エタノール 5質量部
上記で作製した第1の保護フィルム1-1(PETフィルム)および第2の保護フィルム2-1を用い、下記の方法に従って、偏光板101を作製した。
1)偏光子の作製
ポリビニルアルコールフィルムの厚さ60μmの長尺ポリビニルアルコールフィルムを、ガイドロールを介して連続搬送しつつ、ヨウ素とヨウ化カリウム配合の染色浴(30℃)に浸漬して染色処理と2.5倍の延伸処理を施した後、ホウ酸とヨウ化カリウムを添加した酸性浴(60℃)中で、トータルとして5倍となる延伸処理と架橋処理を施し、得られた厚さ12μmのヨウ素-PVA系偏光子を、乾燥機中で50℃、30分間乾燥させて水分率4.9%の偏光子を得た。
下記の各成分を混合し、液状の紫外線硬化型接着剤を調製した。
3,4-エポキシシクロヘキシルメチル-3,4-エポキシシクロヘキサンカルボキシレート
40質量部
ビスフェノールA型エポキシ樹脂 60質量部
ジフェニル[4-(フェニルチオ)フェニル]スルホニウムヘキサフルオロアンチモネート(カチオン重合開始剤)
4.0質量部
第1の保護フィルム1-1の貼合面にコロナ処理を施した後、上記調製した紫外線硬化型接着剤Bを、チャンバードクターを備えた塗工装置によって厚さ3μmで塗工した。また、第2の保護フィルム2-1の貼合面にコロナ処理を施した後、同様に紫外線硬化型接着剤Bを厚さ3μmの厚さで塗工した。
上記偏光板101の作製において、第1の保護フィルムおよび第2の保護フィルムを、表2に記載の組み合わせとなるように変更した以外は、偏光板101の作製と同様にして、偏光板102~106を作製した。
上記で作製した偏光板101を用い、下記の方法に従って、液晶表示装置201を作製した。
(ベンドムラ)
上記作製した液晶表示装置201~206を、40℃95%RHの環境下で24時間放置した。次いで、40℃ドライの環境下で液晶表示装置201~206を黒表示させた状態で、表示画面の4頂点付近の輝度と表示画面中央部付近の輝度との差(中心部と周辺部との画像ムラ)を目視観察した。そして、以下の評価基準に基づいて、ベンドムラの評価を行った。
《評価基準》
◎:ベンドムラが全く認められない。
○:ベンドムラが僅かに認められるが、実使用上問題なし。
△:ベンドムラが認められるが、実使用上は許容される品質である。
×:明らかなベンドムラが認められ、実使用上問題あり。
上記で作製した第2の保護フィルム2-1~2-6をそれぞれA4サイズ(210mm×297mm)にカットし、温度60℃、湿度90%RHの高温高湿サーモ機にて1000時間保存し、湿熱処理サンプルを作製した。次に、湿熱処理したフィルムを、温度23℃、相対湿度55%RHの条件で24時間調湿した。
《評価基準》
◎:ヘイズが0.5%未満である。
○:ヘイズが0.5%以上1.0%未満である。
△:ヘイズが1.0%以上1.5未満である。
×:ヘイズが1.5%以上である。
以上、本発明の実施形態につき説明したが、本発明の範囲はこれに限定されるものではなく、発明の主旨を逸脱しない範囲で種々の変更を加えて実施することができる。
前記第2の保護フィルムにおいて、下記式(i)で定義されるフィルム面内方向のリタデーション値Ro(nm)および下記式(ii)で定義されるフィルムの厚み方向のリタデーション値Rt(nm)が、下記式(iii)および(iv)で規定する条件を満たし、
(i)Ro=(nx-ny)×d
(ii)Rt=((nx+ny)/2-nz)×d
(式中、nxはフィルム面内の遅相軸方向の屈折率、nyはフィルム面内の進相軸方向の屈折率、nzはフィルムの厚み方向の屈折率(屈折率は23℃、55%RHの環境下、波長590nmで測定)、dはフィルムの厚さ(nm)を表す。)
(iii)0nm≦Ro≦10nm
(iv)|Rt|≦25nm
前記第1の保護フィルムおよび前記第2の保護フィルムのうち、前記第2の保護フィルムのみが、紫外線吸収剤を含み、
前記第2の保護フィルムは、主鎖の両末端が水酸基であるポリエステルジオールを含み、
前記第2の保護フィルムは、コア層と、前記コア層の表面側および裏面側に位置し、微粒子を含有する2つのスキン層とを含む積層フィルムであることを特徴とする偏光板。
一対の基板で液晶層を挟持したIPS型の液晶セルとを含み、
前記偏光板は、前記液晶セルに対して視認側に配置され、かつ、前記偏光子に対して前記第2の保護フィルムが前記液晶セル側となるように配置されることを特徴とする液晶表示装置。
4 液晶セル
5 偏光板
11 偏光子
12 光学フィルム(第1の保護フィルム)
13 光学フィルム(第2の保護フィルム)
Claims (6)
- 第1の保護フィルム、偏光子、第2の保護フィルムをこの順で積層した偏光板であって、
前記第2の保護フィルムにおいて、下記式(i)で定義されるフィルム面内方向のリタデーション値Ro(nm)および下記式(ii)で定義されるフィルムの厚み方向のリタデーション値Rt(nm)が、下記式(iii)および(iv)で規定する条件を満たし、
(i)Ro=(nx-ny)×d
(ii)Rt=((nx+ny)/2-nz)×d
(式中、nxはフィルム面内の遅相軸方向の屈折率、nyはフィルム面内の進相軸方向の屈折率、nzはフィルムの厚み方向の屈折率(屈折率は23℃、55%RHの環境下、波長590nmで測定)、dはフィルムの厚さ(nm)を表す。)
(iii)0nm≦Ro≦10nm
(iv)|Rt|≦25nm
前記第1の保護フィルムおよび前記第2の保護フィルムのうち、前記第2の保護フィルムのみが、紫外線吸収剤を含み、
前記第2の保護フィルムは、主鎖の両末端が水酸基であるポリエステルジオールを含み、
前記第2の保護フィルムは、コア層と、前記コア層の表面側および裏面側に位置し、微粒子を含有する2つのスキン層とを含む積層フィルムである、偏光板。 - 前記紫外線吸収剤は、前記第2の保護フィルムにおいて、前記コア層および前記2つのスキン層の両方に含まれる、請求項1に記載の偏光板。
- 前記ポリエステルジオールは、前記第2の保護フィルムにおいて、前記コア層および前記2つのスキン層の両方に含まれる、請求項2に記載の偏光板。
- 前記第2の保護フィルムにおいて、前記コア層および前記2つのスキン層は、セルロースエステルからなる樹脂を含む、請求項1から3のいずれかに記載の偏光板。
- 前記第1の保護フィルムが、ポリエチレンテレフタレートからなる樹脂を含む、請求項1から4のいずれかに記載の偏光板。
- 請求項1から5のいずれかに記載の偏光板と、
一対の基板で液晶層を挟持したIPS型の液晶セルとを含み、
前記偏光板は、前記液晶セルに対して視認側に配置され、かつ、前記偏光子に対して前記第2の保護フィルムが前記液晶セル側となるように配置される、液晶表示装置。
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