WO2008010588A1

WO2008010588A1 - Transparent antireflection plate

Info

Publication number: WO2008010588A1
Application number: PCT/JP2007/064394
Authority: WO
Inventors: Masanao Kamijo; Yasushi Kadowaki; Kazufumi Kai
Original assignee: Showa Denko K. K.
Priority date: 2006-07-18
Filing date: 2007-07-17
Publication date: 2008-01-24
Also published as: TW200813133A

Abstract

By using a cured product of the allyl ester resin composition of the present invention as a substrate, a transparent antireflection plate being excellent in heat resistance and transparency can be provided. Since the antireflection plate is also excellent in adhesion and scratch resistance, it can be produced without providing a hard coating or an adhesion layer at the time of forming an antireflection layer, which improves productivity.

Description

DESCRIPTION

Transparent Antireflection Plate

TECHNICAL FIELD

The present invention relates to an antireflection plate having excellent transparency, heat resistance, adhesion and scratch resistance.

BACKGROUND ART

In transparent materials such as a transparent electrode substrate, a protection plate and a polarizing plate used for a flat panel display and the like, an antireflection layer has been conventionally provided on the surface of the substrate in order to prevent reflection of light. The antireflection layer forms a thin coating having thickness of about wave length of light and lowers light reflectance using the effect of interference of light.

As to such an antireflection layer, there are a single layer structure wherein a material having a low refractive index is used in a single layer and a multi-layer structure wherein a coating of a low refractive index and a coating of a high refractive index are alternated. When an antireflection layer has a multi-layer structure, while it enables to reduce reflections in a wide range of wavelength, transparency tends to decrease when the number of layers to be used increases.

Therefore, a highly transparent resin such as polyethylene terephthalate, polycarbonate and polymethyl methacrylate is used as a substrate for an antireflection plate wherein an antireflection layer is provided.

Also, for resin used as a substrate of such an antireflection plate, such properties as heat resistance, adhesion with an antireflection coating and scratch resistance are required other than transparency, in concrete values, glass transition temperature of 200⁰C or higher and pencil hardness of 3H or more.

The reason why heat resistance is required for a substrate is that heat is applied at the time of forming an antireflection layer, and furthermore, the substrate may be used in a hot environment such as for in-vehicle liquid crystal display.

However, among the resins conventionally used as a substrate, the glass transition temperature of polyethylene terephthalate is about 70⁰C and that of polymethyl methacrylate is about 100⁰C, which are far from having sufficient heat resistance.

On the other hand, the glass transition temperature of polycarbonate is about 140⁰C and polycarbonate is relatively excellent in heat resistance compared to polyethylene terephthalate and polylmethyl methacrylate. However, since polycarbonate has a low surface hardness and tends to scar easily at the time of forming an antireflection coating, it further needs hard coating treatment.

Furthermore, adhesion of polycarbonate and polyethylene terephthalate with an antireflection coating is hardly adequate, and in some cases a bonding layer needs to be provided between the substrate and the antireflection coating, which has become a problem in a production process.

In order to solve the above-mentioned problems, JP-A-H09- 120002 (Patent Document 1) proposes a substrate using norbornene resin. Norbornene resin is excellent in heat resistance and adhesion with an antireflection coating, and consequently can be used as an antireflection plate without hard coating treatment. However, the pencil hardness of norbornene resin is H, and one can hardly say it has sufficiently high pencil hardness. Also, the glass transition temperature of norbornene resin is 160⁰C, and the heat resistance is not satisfactory.

Patent Document 1 : Japanese Laid-Open Patent Publication H9-120002

DISCLOSURE OF THE INVENTION

An objective of the present invention is to solve the above-mentioned problems and to provide an antireflection plate having excellent transparency, heat resistance, adhesion and scratch resistance.

As a result of intensive studies to solve the above- mentioned problems, the present inventors have found that using allyl ester resin as a substrate enables to impart excellent properties such as high adhesion with an antireflection coating, transparency and scratch resistance as well as higher heat resistance to an antireflection plate, compared to a case wherein a conventional resin composition for an antireflection plate is used. The present invention comprises the following 1 to 9:

1. A transparent antireflection plate, which is obtained by forming an antireflection layer on an allyl ester resin substrate, which substrate is prepared by curing an allyl ester resin composition. 2. The transparent antireflection plate described in 1, wherein the allyl ester resin composition contains an allyl ester compound having an ester structure formed of polyvalent alcohol and dicarboxylic acid, having allyl group and/or methallyl group as terminuses.

3. The transparent antireflection plate described in 2, wherein the allyl ester resin composition further contains at least one compound represented by formula (1) .

In the formula, R¹ and R² independently represent either of allyl group or methallyl group, A¹ represents an organic residue having an alicyclic structure or aromatic ring structure derived from dicarboxylic acid.

4. The transparent antireflection plate described in 2, wherein at least one of the allyl ester compounds has a group represented by formula (2) as terminus, and also has a structure represented by formula (3) as constituent unit.

In the formula, R³ represents allyl group or methallyl group, A² represents an organic residue having an alicyclic structure and/or an aromatic ring structure derived from dicarboxylic acid.

In the formula, A³ represents an organic residue having an alicyclic structure and/or an aromatic ring structure derived from dicarboxylic acid, X represents an organic residue derived from polyvalent alcohol, with a proviso that X may have a branched structure through ester bonds, having a group represented by formula (2) as terminus and a group represented by formula (3) as a constituent unit.

5. The transparent antireflection plate described in 4, wherein the dicarboxylic acid in formula (1), (2) or (3) is at least one kind selected from the group consisting of terephthalic acid, isophthalic acid, phthalic acid and 1,4- cyclohexane dicarboxylic acid.

6. The transparent antireflection plate described in any one of 1 to 5, wherein the allyl ester resin composition further contains reactive monomers.

7. The transparent antireflection plate described in any one of 1 to 6, wherein at least one of the antireflection layers comprises SiO₂ or ZrO₂.

8. A display unit using the transparent antireflection plate described in any one of 1 to 7.

9. A window panel using the transparent antireflection plate described in any one of 1 to 7.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail herein below. <Allyl ester resin>

The allyl ester resin in the present invention is a kind of thermosetting resin.

Generally, the term "allyl ester resin" means both prepolymer before cured (including oligomers, additives or monomers) and a cured product thereof. In the present specification, the term "allyl ester resin" means a cured product and the term "allyl ester resin composition" means a prepolymer before cured.

The allyl ester resin composition for the antireflection plate of the present invention is a composition containing a compound having allyl group or methallyl group (hereinafter, both sometimes referred to as " (meth) allyl group") and an ester structure as its main curing component.

The compound having (meth) allyl group and an etser structure can be obtained through (1) esterification reaction between a compound having (meth) allyl group and hydroxy group (here, collectively referred to as "allyl alcohol") and a compound having carboxyl group, (2) esterification reaction between a compound having (meth) allyl group and carboxyl group and a compound having hydroxyl group, or (3) ester exchange reaction between an ester compound consisting of allyl alcohol and dicarboxylic acid and a polyvalent alcohol. In a case where the compound having a carboxyl compound in (1) and (2) is a polyester oligomer of dicarboxylic acid and a diol, the compound may have allyl alcohol ester only at terminus.

Examples of an ester compound consisting of allyl alcohol and dicarboxylic acid in (3) include at least one kind of compound selected from the compounds represented by formula (1) .

In the formula, R¹ and R² independently represent either of allyl group or methallyl group, A¹ represents an organic residue having an alicyclic structure and/or aromatic ring structure derived from dicarboxylic acid. The compound may be contained in the allyl ester resin composition of the present invention as a reactive diluent (reactive monomer) as well as may become a raw material of allyl ester oligomer described later. A¹ in formula (1) is preferably the same with A² and A³ in formulae (2) and (3) described later.

It is preferred that the compound having (meth) allyl group and an ester structure serving as the main cured component in the allyl ester resin composition of the present invention be an allyl ester compound having an ester structure formed of polyvalent alcohol and dicarboxylic acid, having allyl group and/or methallyl group as terminus (hereinafter, the compound is sometimes referred to as "allyl ester oligomer") .

Further, the compound may contain as other components curing agent, reactive monomer, additives and other radically reactive resin components described later.

It is preferred that the allyl ester oligomer of the present invention be a compound having a group represented by formula (2) as terminus, and having a structure represented by formula (3) as constituent unit.

In the formula, A³ represents an organic residue having an alicyclic structure and/or an aromatic ring structure derived from dicarboxylic acid, X represents an organic residue derived from polyvalent alcohol, with a proviso that X may have a branched structure through ester bonds, having a group represented by formula (2) as terminus and a group represented by formula (3) as constituent unit. In the allyl ester oligomer of the present invention, there are at least two terminuses represented by formula (2) , but in a case where X in formula (3) has a branched structure, there are three or more terminuses. In this case, there exist multiple R³' s for each of the terminuses. These R³ ' s need not be of the same kind and the structure of one terminus may include allyl group while that of another terminus may include methallyl group .

Moreover, all the R³ ' s do not necessarily have to be allyl group or methallyl group. To an extent that does not impair curability, some of the R³' s may be a non-polymerizable group such as methyl group and ethyl group.

Similarly, with respect to the structure represented by A² , the terminuses may be different from each other. For example, the structure of A² at one terminus may include a benzene ring while A² at another terminus may include a cyclohexane ring.

A² in formula (2) is an organic residue having an alicyclic structure and/or an aromatic ring structure derived from dicarboxylic acid. The portion derived from dicarboxylic acid is shown as a carbonyl structure adjacent to A². Therefore, A² shows a benzene skeleton or a cyclohexane skeleton.

Although there is no particular limitation on dicarboxylic acid from which A² is derived from, terephthalic acid, isophthalic acid, phthalic acid, 1, 4-cyclohexane dicarboxylic acid, 1, 4-naphthalene dicarboxylic acid, 1, 5-naphthalene dicarboxylic acid, 2, 7-naphthalene dicarboxylic acid, diphenyl- m,m' -dicarboxylic acid, diphenyl-p,p' -dicarboxylic acid, benzophenone-4, 4' -dicarboxylic acid, p-phenylene diacetate, p- carboxyphenyl acetate, methyl terephthalic acid and tetrachlorophthalic acid are preferred. Among these, terephthalic acid, isophthalic acid, phthalic acid and 1,4- cyclohexane dicarboxylic acid are more preferred.

Also, to an extent that does not impair the effects of the present invention, non-cyclic dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, citraconic acid, endic anhydride, chlorendic anhydride or the like may be used.

At least one constituent unit represented by above- described formula (3) is required in allyl ester oligomer. It is ■ preferred that the molecular weight of the whole allyl ester oligomer be increased to a certain level by repetition of this unit, so that appropriate viscosity may be obtained, enhancing workability and toughness of cured product. However, if the molecular weight is too high, the molecular weight between the cross-link points becomes too high, which results in lowering the glass transition temperature (Tg) and may deteriorate the heat resistance. Therefore, it is important to adjust the molecular weight appropriately for purposes.

A preferred range of the weight-average molecular weight of the allyl ester oligomer is from 500 to 200,000, more preferably from 1000 to 100,000.

A³ in formula (3) is an organic residue having an alicyclic structure and/or an aromatic ring structure derived from dicarboxylic acid, and its definition and preferred examples of the compound are the same as in A² in formula (2) .

X in formula (3) represents an organic residue derived from polyvalent alcohol.

Polyvalent alcohol is a compound having two or more hydroxyl groups and X itself represents the skeleton portion except for hydroxyl groups .

Further, in the polyvalent alcohol, since at least two hydroxyl groups have to be bonded, some hydroxyl groups may remain unreacted when the polyvalent alcohol has a valence of three or more. i.e. it has three or more hydroxyl groups.

Examples of polyvalent alcohol include ethylene glycol, propylene glycol, 1,3-propane diol, 1,4-butane diol, 1,3-butane diol, 1,5-pentane diol, neopentyl glycol, 1, 6-hexane diol, 1,4- cyclohexane dimethanol, diethylene glycol, ethylene oxide adduct of isocyanuric acid, pentaerythritol, tricyclodecanedimethanol, glycerine, trimethylol propane, ethylene oxide adduct of pentaerithritol, D-sorbitol and hydrogenated bisphenol-A. There is no particular limitation on production method for these compounds . With respect to the constituent unit represented by formula (3) in the allyl ester oligomer, one type of the constituent unit may be repeated or different types of the unit may be included. That is, the allyl ester oligomer may be a copolymer type. In this case, in one allyl ester oligomer, several kinds of X exist. For example, the structure may include a residue derived from propylene glycol as one X and another residue derived from trimethylol propane as another X. In this case, allyl ester oligomer has branches at trimethylol propane residue. Two or more types of A³ may exist as well. A structural formula (4), an example in a case where R³ is allyl group, A² and A³ are residues derived from isophthalic acid, X is propylene glycol or trimethylol propane, is shown below.

In order to cure the allyl ester resin composition of the present invention, a curing agent may be used. There is no particular limitation on curing agents usable in the present invention. Generally, those used as curing agent for polymerizable resin can be used. Among those, it is preferred that from the view point of initiating polymerization of allyl group, a radical polymerization initiator be added. Examples of radical polymerization initiator include organic peroxides, photo-polymerization initiator and azo compounds. Among these, particularly preferred is organic peroxide in terms of thermally curing the allyl ester resin composition of the present invention.

Examples of organic peroxides usable here include known ones such as dialkyl peroxide, acyl peroxide, hydroperoxide, ketone peroxide and peroxy ester, and specific examples thereof include benzoyl peroxide, 1, 1-bis (t-butylperoxy) cyclohexane, 2, 2-bis (4, 4-dibutylperoxy cyclohexyl) propane, t-butylperoxy-2- ethyl hexanate, 2, 5-dimethyl-2, 5-di (t-butyl peroxy) hexane, 2,5- dimethyl-2, 5-di (benzoyl peroxy) hexane, t-butyl peroxy benzoate, t-butylcumyl peroxide, p-methyl hydroperoxide, t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, di-t- butyl peroxide and 2, 5-dimethyl-2, 5-dibutylperoxy hexyne-3. Examples of above-described photo-polymerization initiator include 2, 2-dimethoxy-l, 2-diphenylethane-l-on, 1- hydroxycyclohexyl phenyl ketone, benzophenone, 2-methyl-l- (4- methyl thiophenyl) -2-morpholino propane-1, 2-benzyl-2- dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-hydroxy-2- methyl-1-phenylpropane-l-on and 2, 4, 6-trimethylbenzoyl diphenyl phosphine oxide.

One of these radical polymerization initiator may be used singly or two or more of them may be used in combination. There is no particular limitation on the blending amount of these curing agents. It is preferred that the blending amount of the curing agent be from 0.1 to 10 mass parts in 100 mass parts of the allyl ester resin composition, more preferably from 0.5 to 5 mass parts. If the blending amount of the curing agent is less than 0.1 mass parts, it is difficult to achieve satisfactory curing rate. If the blending amount exceeds 10 mass parts, the finally obtained cured product sometimes becomes fragile and its mechanical strength deteriorates.

To the allyl ester resin composition of the present invention, reactive monomer (reactive diluent) may be added for the purpose of controlling the curing reaction rate, adjusting viscosity (improvement of workability) , enhancing crosslinking density and imparting functions.

There is no particular limitation on reactive monomers and various types may be used. In view of allowing the reaction with the allyl ester oligomer, preferred is a monomer having a radically polymerizable carbon-carbon double bond such as vinyl group and allyl group. Examples thereof include unsaturated aliphatic acid ester, aromatic vinyl compound, vinyl ester of saturated aliphatic acid or aromatic carboxylic acid or derivatives thereof and crosslinkable polyfunctional monomer. Among these, with crosslinkable polyfunctional monomer, crosslinking density of cured products can be controlled. Preferred examples of the reactive monomer are described below.

Examples of unsaturated aliphatic acid ester include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2- ethylhexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate and methyl cyclohexyl (meth) acrylate;

(meth) acrylates of aromatic esters such as phenyl (meth) acrylate, benzyl (meth) acrylate, 1- naphtyl (meth) acrylate, fluorophenyl (meth) acrylate, chlorophenyl (meth) acrylate, cyanophenyl (meth) acrylate, methoxyphenyl (meth) acrylate and biphenyl (meth) acrylate; haloalkyl (meth) acrylates such as fluoromethyl (meth) acrylate and chloromethyl (meth) acrylate; and glycidyl (meth) acrylate, alkyl amino (meth) acrylate and α- cyanoacrylate ester.

Examples of aromatic vinyl compound include styrene, α- methylstyrene, chlorostyrene, styrene sulfonic acid, 4- hydroxystyrene and vinyl toluene.

Examples of vinyl ester of saturated aliphatic acid or aromatic carboxylic acid and derivatives thereof include vinyl acetate, vinyl propionate and vinyl benzoate.

Examples of crosslinkable polyfunctional monomer include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1,5- pentanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, oligoester di (meth) acrylate, polybutadiene di (meth) acrylate, 2,2-bis(4- (meth) acryloyloxyphenyl) propane and 2, 2-bis (4- (ω- (meth) acryloyloxypolyethoxy) phenyl) propane; diallyl aromatic dicarboxylates such as diallyl phthalate, diallyl isophthalate, dimethallyl isophthalate, diallyl terephthalate, triallyl trimellate, diallyl 2, 6-naphthalene dicarboxylate, diallyl 1,5- naphthalene dicarboxylate, allyl 1,4-xylene dicarboxylate and diallyl 4, 4' -diphenyl dicarboxylate; bifunctional crosslinkable monomers such as diallyl cyclohexane dicarboxylate and divinyl benzene; trifunctional crosslinkable monomers such as trimethylol ethane tri (meth) acrylate, trimethylol propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate, triallyl trimellitate and diallyl chlorenedate; and tetrafunctional crosslinkable monomers such as pentaerythritol tetra (meth) acrylate.

One of the above reactive monomers may be used singly or two or more kinds of them may be used in combination.

There is no particular limitation on the use amount of these reactive monomers. It is preferable that the amount be from 1 to 1000 mass parts based on 100 mass parts of the allyl ester oligomer, more preferably from 2 to 500 mass parts, most preferably from 5 to 100 mass parts. If the use amount of the reactive monomer is less than 1 mass part, the effect of reducing viscosity is small, resulting in deterioration in workability and further, in a case where monofunctional monomer is used in large amounts as reactive monomer, crosslinking density becomes low and heat resistance sometimes becomes insufficient, which is not preferred. If the use amount exceeds 1000 mass parts, transparency of the allyl ester resin itself cannot be expressed or mechanical strength derived from the allyl ester resin deteriorates in some cases, which is not preferred.

<Radically-reactive resin component>

The allyl ester resin composition of the present invention may contain radically-reactive resin components for the purpose of improving the properties of the composition. Examples of the resin components include unsaturated polyester resin and vinylester resin.

Unsaturated polyester resin is the condensation product obtained through esterification reaction between polyvalent alcohol and unsaturated polybasic acid (and if necessary, saturated polybasic acid) , if necessary by dissolving the condensation product in polymerizable unsaturated compound such as styrene. Specifically, Polyester resin Handbook, published by NIKKAN KOGYO SHIMBUN, LTD. in 1988, describes about examples of such a resin in pages 16-18 and 29-37. Such unsaturated polyester resin can be produced by known methods. Vinyl ester resin, also referred to as "epoxy

(meth) acrylate", is a resin having a polymerizable unsaturated group generally produced through ring-opening reaction between an epoxy compound having epoxy group such as epoxy resin and carboxyl group of a compound having a polymerizable unsaturated group such as (meth) acrylic acid or a resin having a polymerizable unsaturated group generally produced through ring- opening reaction between a compound having carboxyl group and epoxy group of a polymerizable unsaturated compound having epoxy groups in molecules group such as glycidyl (meth) acrylate . Specifically, Polyester resin Handbook, published by NIKKAN KOGYO SHIMBUN, LTD. in 1988, describes about examples of such a resin in pages 336-357. Such vinyl ester resin can be produced by known methods . Examples of epoxy resin serving as a raw material for vinylester resin include bisphenol A diglycidyl ether and its high-molecular weight homolog, glycidyl ether of bisphenol A alkylene oxide adduct, bisphenol F diglycidyl ether and its high-molecular weight homolog, glycidyl ether of bisphenol F alkylene oxide adduct and novolak-type polyglycidyl ether.

One of the above radically reactive resin components may be used singly or two or more kinds of them may be used in combination.

There is no limitation on the use amount of the radically reactive resin component. It is preferable that the amount be from 1 to 1000 mass parts based on 100 mass parts of the allyl ester oligomer, more preferably from 2 to 500 mass parts, most preferably from 5 mass parts to 100 mass parts.

If the use amount of the radically reactive resin component is less than 1 mass parts, the effect of enhancing mechanical strength derived from the radically reactive resin component is small, resulting in deterioration in workability and moldability, which is not preferred. If the use amount exceeds 1000 mass parts, heat resistance of the allyl ester resin itself cannot be expressed in some cases, which is not preferred.

To the allyl ester resin composition for the transparent antireflection plate according to the present invention, additives such as UV absorber, antioxidant, defoaming agent, leveling agent, mold release agent, lubricant, water repellant, flame retardant, anticontractile agent and crosslinking aid may be added if necessary, for the purpose of improving hardness, strength, moldability, durability and water resistance.

There is no particular limitation on the antioxidant and those widely used may be employed. Preferred examples among them include phenol-based or amine-based antioxidant serving as radical chain inhibitor, and particularly preferred is phenol- based antioxidant. Specific examples of phenol-based antioxidant include 2, 6-t-butyl-p-cresol, 2, 6-t-butyl-4-ethylphenol, 2,2'- methylene bis (4-methyl-6-t-butylphenol) and 1, 1, 3-tris (2-methyl- 4-hydroxy-5-t-butylphenyl) butane.

There is no particular limitation on the lubricant and those widely used may be employed. Preferred examples among them include metallic soap-based lubricant, aliphatic acid ester- based lubricant and aliphatic hydrocarbon-based lubricant and particularly preferred is metallic soap-based lubricant. Specific examples of metallic soap-based lubricant include barium stearate, calcium stearate, zinc stearate, magnesium stearate and aluminium stearate. These may be used in composite.

There is no particular limitation on the UV absorber and those widely used may be employed. Preferred examples among them include benzophenone-based UV absorber, benzotriazole-based UV absorber and cyanoacrylate-based UV absorber and particularly preferred is benzophenone-based UV absorber. Specific examples of benzophenone-based UV absorber include 2- (2' -hydroxy-5' - methylphenyl) benzotriazole, 2- (2' -hydroxy-5' -butylphenyl) benzotriazole and 2- (2-hydroxy-3' -tert-butylphenyl) benzotriazole.

The additives are not limited by those examples described above and various types of additives may be employed within a range that does not disturb the object and effects of the present invention.

In addition, in curing the allyl ester resin composition for the antireflection plate according to the present invention, solvent may be used if reduction in viscosity is necessary according to the curing method. However, considering that a step of removing solvent is required at a later stage in a case solvent is used, it is preferred that viscosity be adjusted by using the above mentioned reactive monomer. Examples of solvent usable for adjusting viscosity include aromatic hydrocarbons such as toluene and xylene, esters of acetic acid such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ethers such as tetrahydrofuran and 1,4-dioxane and alcohols such as ethyl alcohol, (iso) propyl alcohol and butyl alcohol.

<Viscosity of allyl ester resin composition> The viscosity of the curable resin can be measured by a method according to JIS K6901.

There is no particular limitation on viscosity of the allyl ester resin composition for antireflection plate according to the present invention. It is preferred that the viscosity be suitable for the molding method employed.

For example, in case of cast molding, it is preferable that the viscosity at 25 °C be in a range of 0.01 (Pa-s) to 1, 000 (Pa- s) . If the viscosity at 25 °C is lower than 0.01(Pa*s) or higher than 1,000(Pa-S), workability is deteriorated, which is not preferred.

For example, in case of transfer molding, it is preferable that the viscosity at 80 °C be in a range of 0.01 (Pa-s) to l,000(Pa-s). If the viscosity at 80 °C is lower than 0.01 (Pa-s) or higher than l,000(Pa*s), more molding defects may occur, which is not preferred.

The allyl ester resin composition can be obtained by mixing the allyl ester oligomer, the reactive monomer, the curing agent and various additives by known methods. The composition can be cured with heat, ultraviolet ray or electron beam through coating using a roll-coater or a spin coater by curing methods such as cast molding method and photo fabrication.

The shape of the cured product of the allyl ester resin may be a film or a sheet depending on the shaping method. There is no particular limitation on the thickness of the cured product, but the thickness is generally 0.001 to 10mm, preferably 0.005 to 3mm. The curing temperature in molding the allyl ester resin composition of the present invention is in a range about 30 to about 150 °C, preferably 40 to 130 ⁰C. In consideration for. shrinkage and distortion generated during the curing step, it is preferable that the composition be gradually cured while gradually increasing the temperature.

Generally it is preferable that curing time be 0.5 to 100 hours, preferably 2 to 30 hours.

<Antireflection plate> The antireflection plate of the present invention consists of a substrate composed of the cured product of the above- mentioned allyl ester resin composition and an antireflection layer formed thereon.

The antireflection layer may be formed by a single layer of an antireflection coating, but generally, it is composed of layers having a predetermined optical coating thickness of nd (refractive index: n x coating thickness: d) in order to attain a desired antireflection property, and a coating of a low refractive index and a coating of a high refractive index are alternated to be used.

There is no particular limitation on the thickness of the above-mentioned antireflection layer as long as an antireflection property is exerted, however, the thickness is preferably 0.005 to 5 um. If the thickness of the coating is less than 0.005 μm, it makes difficult to stick the coating fast to the substrate, which may cause a problem of unevenness. On the other hand, if the thickness exceeds 5 μm, the coating becomes too thick and the transparency tends to deteriorate. For the antireflection coating, all known coatings may be applied. For the constituents of the coating, for example, titanium oxide, zirconium oxide, niobium oxide, hafnium oxide, cerium oxide, silicon oxide, magnesium fluoride, aluminum oxide or the like may be used. Among them, in terms of excellent adhesiveness to allylic ester resin, silicon oxide and zirconium oxide are preferred for the antireflection coating.

Examples of a method for forming an antireflection coating include sputtering method, ion plating method and vacuum deposition method. Moreover, it is preferable that the temperature for heating the substrate in the step of forming the coating be thermal distortion temperature of the substrate or lower.

Examples of a sputtering method include normal sputtering method using a target oxide and reactive sputtering method using a target metal. In this step, oxygen, nitrogen or the like may be introduced as reactive gas, or measures such as ozone addition, plasma irradiation and ion assist may be employed. Also, within a range that does not impair the object of the present invention, bias such as direct current, alternate current and high frequency wave may be applied to the substrate.

The antireflection plate of the present invention can be used for various display device films such as for a liquid crystal display, protective plates, polarizing plates, anti- glare films, phase difference films, transparent conductive plates and alternative plates to guard glass used for in-vehicle meters .

EXAMPLES

Hereinafter, the present invention will be explained in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

In addition, measured values described in the Examples and the Comparative Examples of the present invention were measured by the following methods.

[Measurement of glass transition temperature]

The measurement of glass transition temperature (Tg) was performed by thermomechanical analysis (TMA) using a thermoanalyzer TMA-50 (manufactured by Shimadzu Corporation) in the compression mode. The size of a test piece used for the measurement was 3 x 8 x 8 (mm) , and linear expansion coefficient from 30 to 300 ⁰C at temperature increase rate of 5 °C/minute under nitrogen atmosphere (flow rate: 50 mL/min) after temperature had been once raised to 260 ⁰C at a rate of 5 °C/minute and then cooled to 30 ⁰C to obtain the discontinuity point as the glass transition temperature.

[Peeling test]

A grid having 100 sections of 1 millimeters squared was formed on the surface of the antireflection plate using a cutter. According to JIS-D-0202 method, a peeling test was performed by sticking a tape onto the surface of the substrate and removing it. The judgment was indicated by the number of non-peeled sections among the 100 sections, i.e. 100/100 when the antireflection coating was not peeled at all and 0/100 when the coating was completely peeled.

[Pencil hardness]

The pencil hardness of the antireflection plate was evaluated according to JIS-K6894 method.

[Total light transmission]

The total light transmission was measured with an antireflection plate (30mm x 30mm x 3mm) as a test sample in accordance with JIS K7361-1 using a turbidimeter NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

[Synthesis Example 1]

In a 2L-volume three-neck flask equipped with a distillation unit, 1625 g of diallyl terephthalate, 167 g of propylene glycol and 0.813 g of dibutyl tin oxide were placed. The mixture was heated to 180 ⁰C under nitrogen stream to react while distilling off generated. allyl alcohol. At the time point when the amount of the distilled alcohol reached about 170 g, the inside of the reaction system was depressurized to 6.6 kPa over about 4 hours to accelerate the distillation rate of alcohol. At the time point when almost no distilled liquid coming out was observed, the inside of the reaction system was depressurized to 0.5 kPa and reaction was continued for another 1 hour. Then the reaction product was cooled down. The reaction formula is shown below.

Hereinafter, the thus obtained reaction product is called "oligomer (I)".

[Synthesis Example 2]

In a 2L-volume three-neck flask equipped with a distillation unit, 1400 g of diallyl 1,4- cyclohexanedicarboxylate, 165.4 g of trimethylolpropane and 1.40 g of dibutyltinoxide were placed. The mixture was heated to 180 ⁰C under nitrogen stream to react while distilling off generated allyl alcohol. At the time point when the amount of the distilled alcohol became about 150 g, the inside of the reaction system was depressurized to 6.6 kPa over about 4 hours to accelerate the distillation rate of alcohol. At the time point when almost no distilled liquid coming out was observed, the inside of the reaction system was depressurized to 0.5 kPa and reaction was continued for another 1 hour. Then the reaction product was cooled down. Hereinafter, the thus obtained reaction product is called "oligomer (2)".

[Example 1]

To 100 mass parts of oligomer (1) produced in Synthesis

Example 1, 3 mass parts of Perhexa TMH (product name; manufactured by NOF CORPORATION) was added and stirred completely. The mixture was poured into a mold sandwiching a 3- mm silicon rubber spacer between two glass plates. Curing was conducted under the condition of increasing the temperature that the mold was kept in the atmosphere in an oven at 80 ⁰C for two hours, then the temperature was increased from 80 to 100 ⁰C in eight hours and the temperature was kept at 100 ⁰C for two hours, then the temperature was increased from 100 to 120 ⁰C in four hours, and the temperature was kept at 120 ⁰C for two hours, to thereby prepare a resin plate. According to measurement, the cured product had a Tg of 273 ⁰C.

The resin plate was placed in a vacuum deposition device, and two layers of antireflection coatings were formed by a vacuum deposition method. The first and the second layers were made to be a ZrO₂ layer (coating thickness: 120nm) and a SiO₂ layer (coating thickness: 85nm) , respectively.

Here, heating and evaporation of deposition materials of each layer was performed by en electron-beam, while the oxygen introduction amount was adjusted by controlling a magnet valve in conjunction with a vacuum meter so that the inside of the vacuum chamber is always maintained at the vacuum of 1 x 10^~3 Pa.

The peeling test result of the obtained antireflection plate was 100/100, and excellent adhesion was confirmed. The plate had pencil hardness of 4H and total light transmission of 95.7%.

[Example 2]

A resin plate was prepared in the same manner as in Example 1 except that oligomer (2) produced in Synthesis Example 2 was used instead of oligomer (1). According to measurement, the cured product had a Tg of 313°c.

Further, two antireflection layers were laminated on the resin plate in the same way as in Example 1. The first and the second layers were made to be a ZrO₂ layer (coating thickness: 90nm) and a SiO₂ layer (coating thickness: 85nm) , respectively.

The peeling test result of the obtained antireflection plate was 100/100, and excellent adhesion was confirmed. The plate had pencil hardness of 4H and total light transmission of 97.7%.

[Comparative Example 1]

Two antireflection layers were laminated on the commercially available polycarbonate resin plate (Tg: 145°C) in the same way as in Example 1. The first and the second layers were made to be a ZrO₂ layer (coating thickness: 75nm) and a SiO₂ layer (coating thickness: 83nm) , respectively.

The peeling test result of the obtained antireflection plate was 0/100. The plate had pencil hardness of HB and total light transmission of 93.8%.

INDUSTRIAL APPLICABILITY

The antireflection plate of the present invention can be used for various display device films such as for a liquid crystal display, protective plates, polarizing plates, antiglare films, phase difference films, transparent conductive plates and alternative plates to guard glass used for in-vehicle meters .

Claims

1. A transparent antireflection plate, which is obtained by- forming an antireflection layer on an allyl ester resin substrate, which substrate is prepared by curing an allyl ester resin composition.

2. The transparent antireflection plate as claimed in claim 1, wherein the allyl ester resin composition contains an allyl ester compound having an ester structure formed of polyvalent alcohol and dicarboxylic acid, having allyl group and/or methallyl group as terminuses.

3. The transparent antireflection plate as claimed in claim 2, wherein the allyl ester resin composition further contains at least one compound represented by formula (1).

4. The transparent antireflection plate as claimed in claim 2, wherein at least one of the allyl ester compounds has a group represented by formula (2) as terminus, and also has a structure represented by formula (3) as constituent unit.

5. The transparent antireflection plate as claimed in claim 4, wherein the dicarboxylic acid in formula (1), (2) or (3) is at least one kind selected from the group consisting of terephthalic acid, isophthalic acid, phthalic acid and 1,4- cyclohexane dicarboxylic acid.

6. The transparent antireflection plate as claimed in claim 1, wherein the allyl ester resin composition further contains reactive monomers.

7. The transparent antireflection plate as claimed in claim 1, wherein at least one of the antireflection layers comprises SiO₂ or ZrO₂.

8. A display unit using the transparent antireflection plate as claimed in any one of claims 1 to 7.

9. A window panel using the transparent antireflection plate as claimed in any one of claims 1 to 7.