JP6703828B2 - Photocurable antiglare resin composition - Google Patents

Description

The present invention is a hard coat resin that imparts an antiglare property to a polycarbonate resin by a simple coating method, forms a stable appearance surface with little liquid damaging, and easily adjusts the haze value to provide excellent optical characteristics. The present invention also relates to a photocurable antiglare resin composition having the same.

A flat panel display typified by a liquid crystal display or an organic EL display is generally covered with a plastic film or panel having properties such as abrasion resistance and scratch resistance in order to protect the surface. Furthermore, in order to deal with the problem that the reflected light generated at the interface with the reflection of light from the outside or the interface with the air layer makes the displayed image difficult to see, antiglare and antireflection properties for preventing glare are often required. .. As a method of imparting properties such as abrasion resistance, abrasion resistance, and antiglare property to such a plastic cover, a photocurable acrylic resin having high hardness and excellent optical properties is often applied.

As a method for imparting antiglare property that does not deteriorate the image quality to an image display body which has been advanced in high definition in recent years, for example, in the plastic film field, a technique of containing an aggregate of colloidal silica particles in a hard coat layer (Patent Document) 1) etc. have been developed. In addition to the method of imparting unevenness to the resin surface with such fine particles, as a method of imparting antiglare properties in the plastic panel field, an ultraviolet curable coating film having a fine convex shape with a sawtooth cross section on a plastic plate A technique for imparting an antiglare property by combining a shape on a base material and a resin, such as a resin molded body made of (Patent Document 2), has been developed.

Particularly in applications where impact resistance is required, polycarbonate panels are often used as plastic materials, and even in this case, unevenness is formed on the surface of the base material and a clear hard coat resin is applied on top of it. In some cases, antiglare properties were given. However, in this method, in addition to the problem that a material with a flat surface cannot be used and is limited in terms of material selection, since the haze is affected by the uneven shape of the base material, in order to finely adjust the haze value, Had to change the shape of the substrate each time. Therefore, there has been a demand for a photocurable resin that can impart antiglare properties to a polycarbonate panel or a resin molded product having a flat surface by a simple coating method and can easily adjust the haze value.

Japanese Patent Laid-Open No. 10-180950 JP-A-11-44806

The present invention is a hard coat resin that imparts an antiglare property to a polycarbonate resin by a simple coating method, forms a stable appearance surface with little liquid damaging, and easily adjusts the haze value to provide excellent optical characteristics. Another object of the present invention is to provide a photocurable antiglare resin composition.

The invention according to claim 1 has an acrylic copolymer (A) having a hydrophilic functional group and a weight average molecular weight of 5,000 to 100,000 and a bifunctional aliphatic cyclic (meth)acrylate (B). ), a trifunctional or higher functional (meth)acrylate (C), a photopolymerization initiator (D), and at least two kinds of silica (E) having an average particle size of 0.1 μm or more and having different particle sizes. In the above, (E) is two types of silica, a hydrophobic silica (E1) having an average particle size of 0.2 to 0.5 μm and a hydrophobic silica (E2) having an average particle size of 1.0 to 5.0 μm. Provided is a photocurable antiglare resin composition.

The invention according to claim 2 provides the photocurable antiglare resin composition according to claim 1, wherein the (A) is 10 to 30 parts by weight based on 100 parts by weight of the total solid composition excluding (E). ..

The invention according to claim 3 is the photocurable antiglare resin composition according to claim 1 or 2, wherein the (C) is 30 to 50 parts by weight with respect to 100 parts by weight of the total solid composition excluding (E). provide.

The invention according to claim 4 provides a polycarbonate resin molded article having a hard coat layer formed of the photocurable antiglare resin composition according to any one of claims 1 to 3 .

The photocurable resin of the present invention is a hard coat resin that imparts an antiglare property to a polycarbonate resin, forms a stable appearance surface with little occurrence of liquid damaging, and easily adjusts the haze value to provide excellent optical characteristics. It is also useful as an antiglare resin.

The present invention will be described in detail below.

The composition of the present invention comprises a hydrophilic functional group-containing acrylic copolymer (A) having a weight average molecular weight of 5,000 to 100,000 and a bifunctional aliphatic cyclic (meth)acrylate ( B), a trifunctional or higher functional (meth)acrylate (C), a photopolymerization initiator (D), and at least two kinds of silica (E) having an average particle diameter of 0.1 μm or more and having different particle diameters. In addition, in this specification, (meth)acrylate includes both acrylate and methacrylate.

The acrylic copolymer (A) used in the present invention is one of the main resins forming the hard coat layer, and is a copolymer containing at least one unsaturated monomer having a hydrophilic functional group. .. When only an acrylic copolymer that does not have a hydrophilic functional group is used, the abrasion resistance of the coating film of the compound is greater than when an acrylic copolymer containing a hydrophilic functional group is used as a paint. descend. The acrylic copolymer here means a polymer obtained by polymerizing an acrylic monomer as a main component, and may include a non-acrylic monomer as long as the weight content of the monomer is less than 50%.

Examples of the unsaturated monomer having a hydrophilic functional group that constitutes (A) include a carboxylic acid having a vinyl group and an alkyl acrylate having a hydroxyl group. In the former, (meth)acrylic acid, itaconic acid, fumaric acid, maleic acid, etc. However, in the latter, there are 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate and the like. Among these, methacrylic acid and 2-hydroxyethyl (meth)acrylate, which are general-purpose products and are inexpensive, are suitable.

Further, as an unsaturated monomer having no hydrophilic functional group to be copolymerized, there is, for example, an alkyl (meth)acrylate, and methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, hexyl. (Meth)acrylate and the like. In addition, styrene or the like is used as the vinyl monomer in the non-acrylic monomer, but it is preferable that the acrylic copolymer (A) contains an alkyl methacrylate.

The weight average molecular weight of the above (A) needs to be 5,000 to 100,000. When the weight average molecular weight is less than 5,000, abrasion resistance becomes insufficient, and when the weight average molecular weight exceeds 100,000, viscosity becomes high, and appearance and toughness including coatability become insufficient. Further, it is preferable that (A) does not contain an unsaturated group because it relaxes curing shrinkage. The term "does not contain an unsaturated group" as used herein means that it does not contain substantially. In other words, it means excluding those in which an unsaturated group is introduced into the acrylic polymer by a method such as reacting an unsaturated group-containing compound after the acrylic polymer is polymerized. When a saturated group remains, it does not substantially contain an unsaturated group.

Further, the amount of (A) is preferably 10 to 30 parts by weight with respect to 100 parts by weight of the total solid composition excluding (E). When the amount is 10 parts by weight or more, the curing shrinkage can be easily controlled, and when the amount is 30 parts by weight or less, the curability can be enhanced and sufficient hardness can be secured.

The bifunctional aliphatic cyclic (meth)acrylate (B) used in the present invention is intended to react with (C) to form a hard coat layer together with (A) to enhance curability and harden the cured film. Blend with. Examples of the aliphatic cyclic compound include those having a dicyclopentanyl group, a dicyclopentenyl group, an isobornyl group, an adamantanyl group, a tetrahydrofuranyl group, a cyclohexyl group, and the like, which can be used alone or in combination of two or more. Dimethylol tricyclodecane diacrylate is preferred.

The tri- or more-functional (meth)acrylate (C) used in the present invention reacts with the above (B) to form a hard coat layer together with (A) to enhance the curability and harden the cured film or to increase the curing speed. Blend for the purpose of speeding up and improving wear resistance. Specifically, ethoxylated isocyanuric acid triacrylate, pentaerythritol triacrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, ditrimethylol. There are propane tetraacrylate, dipentaerythritol hexaacrylate and the like, which can be used alone or in combination of two or more kinds.

Further, the amount of (C) is preferably 30 to 50 parts by weight based on 100 parts by weight of the total solid composition excluding (E). When the amount is 30 parts by weight or more, rapid curing property can be obtained, and when the amount is 50 parts by weight or less, curing shrinkage can be suppressed and long-term reliability can be secured.

The photopolymerization initiator (D) used in the present invention generates radicals upon irradiation with ultraviolet rays or electron beams, and the radicals trigger the polymerization reaction, and may be general-purpose photopolymerization initiators. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1 -[4-(2-Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl) -Propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide , Phenyl glyoxylic acid methyl ester, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, and the like, which can be used alone or in combination of two or more kinds. When the coating film thickness exceeds 10 μm, it is preferable to combine two or more kinds in order to improve the curability to the deep part. Further, the blending amount is preferably 0.1 to 5% by weight with respect to the radically polymerizable component.

At least two kinds of silica (E) having different average particle diameters having an average particle diameter of 0.1 μm or more used in the present invention are, for example, hydrophobic particles having an average particle diameter of 0.2 to 0.5 μm as the first silica (E1). At least two kinds of silica having different particle diameters, namely, silica and hydrophobic silica having an average particle diameter of 1.0 to 5.0 μm as the second silica (E2) are included. By combining two or more kinds of silica having different particle diameters, it is possible to increase the haze with a relatively small amount of addition as compared with the case where they are used alone, and it is possible to suppress glossiness and reduce glare. When silica having an average particle diameter of less than 0.1 μm is used, it is necessary to increase the addition amount in order to increase the haze, and since it becomes a factor that deteriorates other physical properties, it is necessary to select at 0.1 μm or more. The combination of the particle diameters of (E1) and (E2) shown here is preferable because the physical properties are well balanced. The average particle size can be measured by a laser diffraction method according to JISZ 8825-1 using SALD-7500 nano (manufactured by Shimadzu Corporation).

The (E) is not a powder but a solvent having a good compatibility with the photocurable resin so that it can be easily mixed and dispersed in a mixture containing the (A), (B), (C) and (D). It is preferable that the dispersion is a dispersion liquid. Examples of the solvent include methanol, isopropyl alcohol, ethylene glycol, butanol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, toluene and xylene. Of these, preferred dispersion solvents are methyl isobutyl ketone, isobutyl alcohol, and methyl ethyl ketone, which may be used alone or in combination of two or more. The dispersion method is not particularly specified, and for example, silica powder may be added to the dispersion solvent and sufficiently stirred with a disper. Further, the dispersion may contain an additive such as a dispersion aid which facilitates the dispersion of silica.

The mixing ratio of (E1) and (E2), which is an example having different particle diameters of (E), can be arbitrarily selected, and haze can be increased by increasing the total mixing amount. Haze can be increased with a small addition amount by using a mixture of (E1) and (E2) having different particle diameters, rather than using them individually. Further, as the silica particles to be used, silica (E3) to (En) having different particle diameters may be mixed.

Further, (E) can be added later to the mixture containing (A), (B), (C), and (D) to mix and disperse, so that the appearance (E) can be confirmed in the production process. By changing the weight ratio of ), it is possible to easily adjust to any haze value.

The photocurable transparent resin composition of the present invention is a UV absorber, a surface modifier, an antioxidant, a tackifier, a flame retardant, a silane coupling agent, and a colorant, if necessary, within a range that does not impair the performance. Additives such as, and diluted thinner can be added.

Examples of the diluent thinner include alcohol-based, ether-based, ketone-based, and aromatic-based thinners, which can be used alone or in combination of two or more so as to meet a desired viscosity. Especially in the case of spray coating, the appearance is likely to change due to the thinner added, and if the compatibility with the resin is poor, uneven thickness, resin pools, and whitening of the film may occur. It is preferable to select a thinner that has good compatibility with the dispersion solvent in (1).

There is no particular limitation on the method for applying the photocurable antiglare resin composition of the present invention to a substrate, and a planar shape such as a polycarbonate panel includes a bar coating method, a knife coating method, a roll coating method, a spin coating method. A coating method, a dip coating method and the like can be mentioned, but the spray coating method is useful for resin moldings having an uneven surface instead of a flat shape. Further, this method is also excellent as a method for applying a large area to a planar shape without a large capital investment.

After coating on the substrate, the film is dried and then irradiated with an active energy ray typified by ultraviolet rays to form a hard coat layer having an antiglare property. A high pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, and the like are used as a light source when irradiating with ultraviolet rays, and an integrated light amount of 100 to 1,000 mJ/cm 2 is suitable.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these specific examples. The composition in which (A), (B), (C), (D), diluted thinner and the like are mixed before addition of (E) is referred to as a main component. Unless otherwise noted, the room temperature was measured at 25° C. and 65% relative humidity.

Preparation of Acrylic Copolymer 1 1.2 parts by weight of dilauroyl peroxide was added to 448 parts by weight of methyl ethyl ketone and heated at 70° C. for 30 minutes to dissolve, and 50 parts by weight of methacrylic acid as an acrylic monomer. , 90 parts by weight of butyl acrylate, 100 parts by weight of methyl methacrylate, and 1.2 parts by weight of NOFMER MSD (trade name: 4-methyl-2,4-diphenylpentene-1 manufactured by NOF CORPORATION) were mixed. The mixture was added dropwise over 4 hours to carry out stirring polymerization. Then, the mixture was further stirred at 80° C. for 4 hours to obtain an acrylic copolymer 1 containing a hydrophilic functional group (solid content 35%, weight average molecular weight 50,000). In addition, GPC (gel permeation chromatography) was used for the weight average molecular weight measurement, and a polystyrene-based molecular weight was measured and calculated using a styrenedivinylbenzene-based column in a THF developing solvent.

Main agent 1
In the light-shielding bottle, the acrylic copolymer 1 prepared above and DCP-A (trade name: dimethylol tricyclodecane diacrylate manufactured by Kyoeisha Chemical Co., Ltd.) as (B) and DPHA (commodity) as (C) Name: Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), (D) Irgacure 184 (trade name: BASF Japan Co., Ltd.), and UV absorber Tinuvin 400 (trade name: BASF Japan Co., Ltd.), diluted. AD plastic thinner #11 (manufactured by Oshin Chemical Co., Ltd.) as a thinner and BYK-UV3570 (trade name: manufactured by BYK-Chemie Co., Ltd.) as a surface conditioner were added in the amounts shown in Table 1 until the mixture became uniform using a stirring and defoaming machine. The main agent 1 was prepared by stirring.

Main agent 2-7
In addition to the raw materials used in the hard coat base material 1, 1.6HX-A (trade name: Kyoeisha Chemical Co., Ltd., 1.6 hexanediol diacrylate) and 14EG-A ((trade name Table 1 shows FA-513AS (manufactured by Hitachi Chemical Co., Ltd., dicyclopentanyl acrylate) as monofunctional acrylate, and IrgacureTPO (trade name: manufactured by BASF Japan) as (D). The amount shown in was added and the mixture was stirred using a stirring and defoaming machine until it became uniform, to prepare the main ingredients 2 to 7.

Z-AD-2 (trade name: manufactured by Aika Kogyo KK, solid content: 17%) was used as (E1), and Z-AD-3 (commodity) was used as (E2), using the compounded base agents 1 to 7 of Examples and Comparative Examples. Name: Aika Kogyo KK, solid content 17%), MEK-ST (trade name: Nissan Kagaku KK, solid content 30%) as a silica dispersion, and AD thinners #2800 and #9800 (trade name) as dilution thinners. : Taishin Kagaku Co., Ltd.) was put in the amount shown in Table 2 and stirred to prepare Examples 1 to 3 and Comparative Examples 1 to 9. Here, Z-AD-2 of (E1) is hydrophobic silica having an average particle size of 0.3 to 0.4 μm dispersed in a ketone solvent, and Z-ZD-3 of (E2) is alcohol-based or ketone-based. MEK-ST is a hydrophobic silica having an average particle size of 1.5 to 2.5 μm dispersed in a mixed solvent of ether and ether, and MEK-ST is a hydrophobic silica having an average particle size of 0.01 to 0.03 μm dispersed in a ketone solvent. It is silica.

Table 1

Table 2

The evaluation method was as follows.

Preparation of measurement sample A photocurable resin composition was spray gun (W101-101G, Anest Iwata) on a polycarbonate plate PC1600 (trade name: manufactured by Takiron Co., Ltd., 50×70 mm, thickness 2 mm) to a thickness of 10 μm. (Manufactured by I.K. Co., Ltd.), and using an electrode UV irradiation device ECS-1511U manufactured by iGraphics Co., Ltd., with a high pressure mercury lamp, an output of 1.5 kw and a line speed of 0.72 m/min. Then, the sample was cured to prepare a measurement sample. In addition, when a sticky feeling due to finger touch remains under these curing conditions, the curability was rated as x.

Appearance (leveling property and accumulation): The leveling property of the surface at the time of coating the photocurable resin composition and the outline of the paint at the edge of the plate were visually evaluated. The leveling property was evaluated as ◯ when the coating surface did not have a wavy appearance without uneven coating. In addition, the tamari was marked as ○ when the difference in appearance between the center and the end of the coated plate was not significantly large.

Adhesion: Based on the cross-cut method of JIS K 5600-5-6, make 10×10 squares on the coated surface at 1 mm intervals, and attach cellophane tape CT-24 (trade name: Nichiban Co., Ltd.), Check the peeling condition by pulling upward. The squares that did not peel off were counted, and no peeling was rated as ◯.

Pencil hardness: Based on JIS K 5600, a scratch test was performed by applying a load of 100 g from directly above a pencil fixed at an angle of 45 degrees, and the pencil hardness without scratches was displayed. The evaluation was evaluated as 2H or higher.

Total light transmittance: Based on JISK7361-1, it was measured twice using a haze guard manufactured by Toyo Seiki Seisakusho, and the measured value of the polycarbonate plate alone was subtracted to obtain the total light transmittance. In the evaluation, a total light transmittance of 89% or more was evaluated as ◯.

Haze and reproducibility: Based on JIS K 7136, the haze was measured three times using a haze guard manufactured by Toyo Seiki Seisakusho, and the haze was calculated by subtracting the measured value of the polycarbonate plate alone. The haze was evaluated as ◯ when the haze was 4 to 15%. The reproducibility was evaluated as ◯ when the difference between the measured values of three times was 0.5% or less.

Glossiness: Based on JIS Z 8741, the glossiness (60°) was measured twice using a digital variable angle glossmeter manufactured by Suga Test Instruments.

Evaluation results Table 3

Each of the resin compositions of Examples has stable coating properties such as adhesion and pencil hardness, stable optical properties such as turbidity and glossiness, and the appearance after spray coating does not show any tampering and is good. there were.

On the other hand, Comparative Examples 1 and 2 not containing (B) were poor in haze reproducibility, and 1 was high in haze value and low in pencil hardness. Comparative Example 3 not containing (C) had low total light transmittance and pencil hardness, and also had poor haze value and reproducibility. Similarly, Comparative Example 4, which did not contain (C), was inferior in curability and could not be evaluated otherwise. Comparative Examples 5 to 8 containing only (E1) and (E2) were inferior in terms of haze value or appearance (tamari), and Comparative Example 9 containing silica having a small average particle diameter had a low haze value. However, neither was suitable for the present invention.

The present invention is a hard coat resin that imparts an antiglare property to a polycarbonate resin by a simple coating method, forms a stable appearance surface with less liquid damaging, and easily adjusts the haze value to provide excellent optical characteristics. It is also useful as a photocurable antiglare resin composition having both.

Claims (4)

An acrylic copolymer (A) having a hydrophilic functional group and a weight average molecular weight of 5,000 to 100,000, a bifunctional aliphatic cyclic (meth)acrylate (B), and a trifunctional or higher functional and (meth) acrylate (C), a photopolymerization initiator and (D), and the average particle size of 0.1μm or more of at least two particle size different silica (E), only contains the (E) is A photocurable antiglare resin which is two kinds of silica, a hydrophobic silica (E1) having an average particle diameter of 0.2 to 0.5 μm and a hydrophobic silica (E2) having an average particle diameter of 1.0 to 5.0 μm. Composition. The photocurable antiglare resin composition according to claim 1, wherein the (A) is 10 to 30 parts by weight based on 100 parts by weight of the total solid composition excluding (E) . The photocurable antiglare resin composition according to claim 1 or 2, wherein the (C) is 30 to 50 parts by weight based on 100 parts by weight of the total solid composition excluding (E) . A polycarbonate resin molded product having a hard coat layer formed of the photocurable antiglare resin composition according to claim 1.