WO2007132815A1

WO2007132815A1 - Light diffusing styrene resin multilayer plate

Info

Publication number: WO2007132815A1
Application number: PCT/JP2007/059878
Authority: WO
Inventors: Mitsutoshi Toyama
Original assignee: Ps Japan Corporation
Priority date: 2006-05-15
Filing date: 2007-05-14
Publication date: 2007-11-22
Also published as: TWI343487B; JPWO2007132815A1; JP5048659B2; TW200801590A

Abstract

Disclosed is a light diffusing styrene resin multilayer plate comprising a substrate layer (A) and a coating layer (B) containing a styrene resin or a (meth)acrylate-styrene resin and arranged on one or both sides of the substrate layer (A). The substrate layer (A) contains a rubber-modified styrene resin containing a styrene polymer forming the matrix and rubbery polymer particles dispersed, like islands, in the matrix. The cross section of each rubbery polymer particle has a sea-island structure containing the styrene polymer particle inside. The rubber-modified styrene resin is composed of 1-10% by weight of the rubbery polymer and 99-90% by weight of the styrene polymer, and the particle diameter of the rubbery polymer particles is 1.0-5.0 µm. The value of “weight of the styrene polymer/weight of the rubbery polymer” in the methylethylketone insoluble fraction of the rubber-modified styrene resin is within the range of 0.5-1.5.

Description

Specification

Light-diffusing styrene resin laminate

Technical field

[0001] The present invention relates to a light-diffusing styrene-based resin laminate that is low in hygroscopicity, has low light transmission yellowness, is excellent in light diffusivity, light transmittance, and impact resistance, and is suitable for practical use.

Background art

In recent years, a liquid crystal television has been attracting attention as a television that replaces a cathode ray tube television. Since liquid crystal is not a self-luminous device such as a cathode ray tube television, a light source device called a knock light device is required on the back of the liquid crystal. With the spread of LCD TVs, the size of backlights has increased, and with this, the conversion of backlight devices from edge-light or side-light types to direct-type backlight devices has rapidly progressed. In the direct type backlight device, a light diffusion sheet called a light diffusion plate is used to diffuse light from the lamp. The light diffusing plate is a milky white resin plate with light diffusing particles added to a transparent resin, which diffuses the light of the lamp so that the shape of the lamp cannot be seen through, and diffuses the light uniformly to brighten the screen. This is to reduce the unevenness of the thickness. The function required of the light diffusing plate was to improve the optical characteristics in a trade-off relationship between high transmission and high diffusion.

[0003] Although a methacrylic resin has been used as the transparent resin used for the light diffusion plate, styrene has a lower hygroscopicity than the methacrylic resin from the viewpoint of preventing warpage due to water absorption. The system has moved to rosin. In addition, a light diffusing plate in practical use is a laminate in which a resin having a light diffusibility is laminated with a resin having a performance necessary for the light diffusing plate, such as light resistance, as a coating layer. The board is put into practical use.

[0004] With regard to the technology of high transmission and high diffusion of a light diffusing plate, a method of blending fine particles having different refractive indexes into a transparent resin has been disclosed for a long time. For example, 1 to: technology for blending fine particles of LO / zm (Patent Document 1), technology for blending fine particles of 10 to 50 / ζ πι (Patent Document 2), 1 to 6 / ζ πι of silicone resin fine particles and Technology that uses 1 to 7 m of inorganic powder together (Patent Document 3), Technology that uses cross-linked resin particles of less than 5 μm and 5 to 10; ζ ΐη (Patent Document 4), 1 Examples include a technique of blending a light diffusing agent of ˜20 μm (Patent Document 5). [0005] Furthermore, there has been proposed a light diffusing laminate in which a resin containing fine particles in a transparent resin is multilayered as a base material layer, and functions such as light resistance and antistatic properties are imparted to the coating layer (Patent Document 5). ~

6).

[0006] However, regardless of whether the fine particles to be blended in the transparent resin are organic or inorganic, these fine particles have low affinity with the transparent resin and have low impact resistance, and are cracked during handling or transportation. In some cases, chipping may occur.

[0007] For the purpose of improving impact resistance, a technique of adding an acrylic multilayer structure polymer is also disclosed (Patent Documents 7 to 9), but the particle diameter of the multilayer structure polymer usually produced by emulsion polymerization is disclosed. Is less than 0.5 m, which is not preferable because the yellowness of the transmitted color is high.

[0008] As a styrene resin having impact resistance, there is a rubber-modified styrene resin (impact-resistant polystyrene). However, the conventional rubber-modified styrene resin has a high yellowness of transmitted color. Had a problem inferior in light diffusion transmittance. Patent Document 10 discloses that the particle diameter dispersed in the rubber-modified styrene-based resin and the cumulative volume ratio of the particles are within a specific range, thereby providing excellent light transmittance and light diffusibility. Is disclosed. Although this technology has improved the diffuse transmission of light, it is desired to improve the yellowness of the transmitted color.

[0009] On the other hand, with the spread of LCD televisions and the increase in size, the price of products has decreased, and there is a need to reduce the cost of light diffusing plates, which are knocklight components. A light diffusing agent has been added to the current styrene-based resin. There is a demand for a novel light diffusing plate capable of reducing the cost compared to the added light diffusing plate. Patent Document 1 Japanese Patent Publication No. 60-21662

Patent Document 2 Japanese Patent Application Laid-Open No. 60-139758

Patent Document 3 Patent No. 2512544

Patent Document 4 Japanese Patent Laid-Open No. 11-60966

Patent Document 5 JP 2004--50607 A

Patent Document 6 Japanese Patent Laid-Open No. 11-5241

Patent Document 7 JP 08-198976 A

Patent Document 8 JP 2000-296581 A

Patent Document 9 JP 2004-90626 A Patent Document 10: Japanese Unexamined Patent Publication No. 2003-2937

Disclosure of the invention

Problems to be solved by the invention

[0011] The present invention is a light diffusivity, light transmissivity, and impact resistance with low moisture absorption and low yellowness of transmitted light, which is suitably used for a light diffusion plate that is a backlight component of a liquid crystal display or a liquid crystal television. An object of the present invention is to provide a light diffusible styrene-based resin laminate having excellent resistance. Means for solving the problem

[0012] In order to solve the above problems, the present inventors have studied in detail the structure and polymerization method of reinforced rubber particles in impact-resistant polystyrene, and as a result, a rubber-modified styrene system having a specific rubber particle structure as a dispersed phase. It has been found that the above problems can be solved by laminating styrene-based resin or (meth) acrylate ester-styrene-based resin on both surfaces or one surface of the resin layer, and the present invention has been completed. .

[0013] That is, the present invention is as follows.

1) a styrenic polymer forming a matrix and rubbery polymer particles dispersed in islands in the matrix, the cross section of the rubbery polymer particles being a sea island containing the styrenic polymer particles A rubber-modified styrene resin having a structure comprising 1 to 10% by weight of a rubbery polymer and 99 to 90% by weight of a styrene polymer, and the rubbery polymer particles have a particle size of 1 0 to 5.0 m, the value of (weight of styrene polymer Z weight of rubber polymer) in the methyl ethyl ketone insoluble content of rubber-modified styrene resin is 0.5 to 1.5. Substrate layer (A) comprising the rubber-modified styrene-based resin in the range, and styrene-based resin or (meth) acrylic ester-styrene-based resin on both surfaces or one surface of the substrate layer (A). A light-diffusing styrene-based resin laminate comprising a coating layer (B) comprising

2) The light-diffusing styrene-based resin laminate according to 1), wherein the rubbery polymer particles used in the substrate layer (A) have a particle size distribution in the range of 1.0 to 1.6.

3) The light-diffusing styrene-based resin according to 1) or 2), wherein the swelling index of the rubber-modified styrene-based resin used in the substrate layer (A) with respect to toluene is in the range of 5.0 to 10.0. Laminated board.

4) Styrenic resin or (meth) acrylic acid ester used in the coating layer (B) The light-diffusing styrene-based resin laminate according to any one of 1) to 3), wherein the ethylene-based resin is a rubber-modified styrene-based resin or a rubber-modified (meth) acrylate ester-styrene-based resin.

5) The coating layer (B) contains 0.03 to 5 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the resin used in the coating layer (B). The light diffusing styrene-based resin laminate according to claim 1.

6) A light diffusing plate for a backlight comprising the light diffusing styrene-based resin laminate according to any one of 1) to 5).

The invention's effect

[0014] The light diffusing styrene-based resin laminate of the present invention has low moisture absorption, low yellowness of transmitted light, and is excellent in light diffusibility, light transmittance and impact resistance. And this laminated board is used suitably as a light-diffusion board of liquid crystal display devices, such as a lighting fixture, an electric signboard, a liquid crystal display, and a liquid crystal television.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, the present invention will be described in detail.

[0016] The matrix resin of the rubber-modified styrene resin used in the substrate layer (A) of the present invention is a styrene polymer. Examples of the styrenic monomer that forms the styrenic polymer include styrene, α-methylol styrene, ρ-methylol styrene, p-t-butyl styrene, and the like. These may be used alone or in combination of two or more. May be. Of these, styrene is preferred. If necessary, other monomers that can be copolymerized with the styrenic monomer may be used in a range that does not impair the object of the present invention. Examples of other copolymerizable monomers used here include cyanobyl monomers such as acrylonitrile and meta-tallow-tolyl, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic acid ester monomers such as butyl, anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide And dicarboxylic acid imide group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid.

[0017] The amount of other monomers copolymerizable with the styrenic monomer is 100 wt. % Is preferably 50% by weight or less, more preferably 25% by weight or less, and still more preferably 10% by weight or less.

[0018] The rubber-modified styrene-based resin used for the substrate layer (A) of the present invention has a structure as shown in FIG. In FIG. 1, 1 is a styrenic polymer serving as a matrix, 2 is a rubbery polymer (particles) dispersed in the matrix, and 3 is a styrene-based polymer encapsulated in the rubbery polymer. It is a polymer. The rubber-like polymer particles that are the dispersed phase of the rubber-modified styrene-based resin of the present invention are dispersed in islands in the matrix, and the cross-section of the rubber-like polymer particles is a sea island containing the styrene-based polymer. Forming a structure. The encapsulated styrenic polymer preferably has a very small particle size and is uniform! /.

[0019] The rubbery polymer formed by forming rubbery polymer particles is polybutadiene rubber (low cis bond content !, low cis polybutadiene, high cis bond content! Styrene-butadiene copolymer (random and block styrene-butadiene copolymer (SBR)), and polybutadiene rubber is preferred, especially low-cis polybutadiene. The content of the styrene polymer in the styrene-butadiene copolymer is preferably 25% by weight or less, and more preferably 10% by weight or less. When the content of the styrene polymer in the styrene-butadiene copolymer increases, the refractive index with the matrix becomes close and the light diffusibility tends to decrease.

[0020] The rubber-modified styrenic榭脂used for the substrate layer (A) of the present invention, the rubber-like polymer 1 to 1 0 weight ^_0/0, the range of the styrene-based polymer 99 to 90 weight ^_0/0 is there. Preferably the rubbery polymer 2-10 wt ^_0/0, styrene polymer 98-90 wt ^_0/0, more preferably the rubbery polymer 3-9 wt%, a styrene-based polymer 97-91 wt% range It is. The rubbery polymer is less than 1 wt ^_0/0, impact resistance, light diffusibility decreases, more than 10 wt%, the rigidity, optical transparency is low down. Here, the weight ratio of the styrene-based polymer is determined in the styrene-based polymer and rubber-like polymer particles grafted to the styrene-based polymer, which is a matrix of the rubber-modified styrene-based resin, and the rubber-like polymer. It is the total with the styrene-based resin included. Furthermore, when the rubber-like polymer is a styrene-butadiene copolymer, the weight ratio of the styrene component in the copolymer is also included.

[0021] The rubber-modified styrene-based rubber-like polymer dispersed particles have a particle size of 1.0 to 5.0. / zm, preferably ί or 1.2 to 4.0.111, more preferably 1.3 to 3.5 m. When the particle diameter is less than 1. O / zm, the light diffusibility is lowered, and when used as a light diffusing plate, the light source can be easily seen through, the yellowness of the transmitted color is increased, and the impact resistance is increased. Inferior to sex. On the other hand, when the particle diameter exceeds 5.0 m, in order to satisfy the high light diffusibility, a large amount of additive of the rubber-like polymer dispersed particles is required, which is not preferable because the rigidity is lowered. Furthermore, it is difficult to reduce the ratio of (weight of styrene polymer Z weight of rubber-like polymer) in methyl ethyl ketone insoluble matter, and as a result, the yellowness of the transmitted color increases, which is not preferable.

[0022] The particle size distribution determined by the ratio of the volume unit median diameter to the number unit median diameter of the dispersed particles is preferably in the range of 1.0 to 1.6, more preferably 1.0 to 1. .5. When the particle size distribution exceeds 1.6, the yellowness of the transmitted color tends to increase.

[0023] The value of (weight of styrenic polymer Z weight of rubbery polymer) in the methylethylketone insoluble content of rubber-modified styrenic resin is in the range of 0.5 to 1.5, Preferably, it is 0.6 to 1.4, and more preferably 0.7 to 1.3. If the value of (weight of styrene polymer Z weight of rubber-like polymer) is less than 0.5, impact resistance is lowered, which is not preferable. On the other hand, if the value of (weight of styrene-based polymer Z weight of rubber-like polymer) exceeds 1.5, the yellowness of the transmitted color increases, making it difficult to adjust the color when used as a diffusion plate. It is not preferable. Further, as the value of (weight of styrene polymer Z weight of rubbery polymer) increases, the light diffusibility decreases.

[0024] The content of the rubber-like polymer particles, which are the dispersed phase of the rubber-modified styrene-based resin, is measured by dissolving and dispersing the resin in a solvent, centrifuging, and then decanting to remove soluble components (mat It is determined by the operation of drying the insoluble matter after separating the insoluble matter (gel content) as the dispersed phase. Generally, toluene is used as a solvent. However, when dispersed, V, the particle diameter is small, or the degree of cross-linking of the rubbery polymer is low! In the case of rubber-modified styrene resin, when toluene is used, the affinity between toluene and gel is good. In some cases, gel content flows out during decantation during measurement, and the content of the dispersed phase may be lower than the true value. Therefore, in the present invention, methyl ethyl ketone is used as a solvent. By using methyl ethyl ketone, it is possible to measure the content of the dispersed phase that prevents the gel from flowing out during decantation. [0025] Rubber-modified styrene-methyl E chill ketone insoluble components in榭脂3 to 25 weight ^_0/0 more preferably preferably range of instrument 4 to 23 wt%, more preferably from 6 to 20 wt% . The light diffusibility tends to decrease as the amount of methyl ethyl ketone insolubles decreases, and the light transmittance tends to decrease as it increases.

[0026] The swelling index of the rubber-modified styrene-based resin with respect to toluene is preferably in the range of 5.0 to 10.0, more preferably 6.0 to 9.0. More preferably, it is 6.0 to 8.0. Swell? The number represents the crosslink density of the rubbery polymer. The smaller the value, the higher the crosslink density, and the lower the crosslink density. As the swelling index decreases, the strength of the rubber-modified styrene-based resin tends to decrease. On the other hand, as the swelling index increases, the dispersed particles tend to be deformed due to the orientation during molding, and the light diffusibility tends to decrease.

[0027] An example of a method for producing a rubber-modified styrene-based resin used for the substrate layer (Α) of the present invention is shown.

[0028] The rubber-modified styrene-based resin polymerization method of the present invention includes bulk polymerization, solution polymerization, bulk suspension polymerization and the like. Among these, bulk polymerization or solution polymerization is preferred, and continuous bulk polymerization or Continuous solution polymerization is particularly preferred in terms of productivity and economy. Specifically, a raw material solution comprising a rubber-like polymer, a styrene monomer, other monomers copolymerizable with a styrene monomer as required, a solvent, a polymerization initiator, a chain transfer agent, etc. The first polymerization solution, the styrenic monomer and, if necessary, the styrenic monomer, which are obtained by polymerization and remain in a state where the rubber-like polymer does not become particles as the polymerization proceeds. Stir and mix the polymerization solution of the second stream in the middle of polymerization of the raw material solution consisting of other monomers copolymerizable with the monomer and solvent, polymerization initiator, chain transfer agent, etc. with high shear force continuously. Let After forcibly forming particles by this stirring and mixing, the polymerization is further advanced, and the solvent and unreacted monomer are removed by heating and devolatilization to obtain a rubber-modified styrene-based resin. The recovery device is a device that is commonly used in the production of styrene-based resin. For example, a flash tank system, an extruder with a multistage vent, or the like can be used.

[0029] The particle diameter of the rubber-like polymer particles is adjusted by adjusting the rotation speed (shearing force) of a mixing stirrer that continuously stirs and mixes the first stream polymerization solution and the second stream polymerization solution under high shear. The first flow The polymerization rate can be controlled by controlling the polymerization rate of the polymerization solution, the molecular weight of the styrenic polymer in the polymerization solution in the first stream, and the like. Adjustment of the value of (weight of styrene-based polymer Z weight of rubber-like polymer) in methyl ethyl ketone insolubles is based on the amount of rubber-like polymer in the first stream raw material solution and the polymerization of the first stream. It can be carried out by controlling the mixing ratio of the solution and the polymerization solution in the second stream, the amount of the styrene polymer in the mixed solution, the rotational speed of the mixing stirrer, and the like.

[0030] Adjustment of the swelling index of toluene-insoluble matter with respect to toluene can be carried out by controlling the temperature of the recovery system.

[0031] In the production method, the amount of the rubbery polymer in the raw material solution of the first stream is preferably 6% by weight or more, more preferably 8% by weight or more, and the amount of the polymerization initiator in the raw material solution. 100 to: LOOOppm, more preferably 300 to 800ppm, the mixing ratio of the polymerization solution of the first stream and the polymerization solution of the second stream is preferably 1: 1 to 3: 7, and the mixture solution The amount of the styrene-based polymer is preferably 24 to 45% by weight. Furthermore, it is preferable to continuously stir and mix the first stream polymerization solution and the second stream polymerization solution with higher shearing force.

[0032] A light-transmitting molded article made of rubber-reinforced styrene-based resin using a similar manufacturing method is the first flow shown in the force example disclosed in JP 2003-2937 A. Since the mixing ratio between the polymerization solution and the polymerization solution in the second stream is 2: 1 and the amount of the styrene polymer in the mixture is small, this production method uses the rubber-modified styrene system of the present invention. The value range of (weight of styrene-based polymer Z weight of rubber-like polymer) in the methylethylketone insoluble matter of the resin cannot be satisfied. In addition, a conventional method of polymerizing a styrene monomer in the presence of a rubber polymer to form a rubbery polymer or a method of adding a styrene polymer in order to advance the particle formation time, A rubber-modified styrene-based resin used for the substrate layer (A) of the present invention cannot be obtained.

[0033] The amount of the rubber-like polymer in the rubber-modified styrene-based resin can be controlled by adjusting the content and the polymerization rate of the rubber-like polymer in the raw material so that the target content is obtained. it can. The rubber-modified styrene-based resin used for the substrate layer (A) of the present invention can be produced by the above production method. As another method, a rubber-modified styrene-based resin obtained by the above production method is mixed with a styrene-based resin such as a polystyrene resin that does not contain a rubbery polymer. It can also be produced by dilution. When the rubber-modified styrene resin is produced by the above production method, the amount of the rubber-like polymer in the rubber-modified styrene resin is preferably

4-10 weight ^_0/0, more preferably 4-9 weight ^_0/0, more preferably from 5 to 9 weight ^_0/0. When the amount of the rubbery polymer is less than 4%, the value of (weight of styrene polymer Z weight of rubbery polymer) in methyl ethyl ketone insolubles tends to increase. When it exceeds, the viscosity of the raw material solution in the first flow becomes high and liquid feeding tends to be difficult.

[0034] Organic peroxides used as polymerization initiators include baroxyketals, dialkyl peroxides, disilver oxides, peroxydicarbonates, peroxyesters, ketones Examples include peroxides and hide mouth peroxides.

[0035] Ethylbenzene, toluene, xylene, or the like can be used as the polymerization solvent.

[0036] As the chain transfer agent, mercaptans such as α-methylstyrene dimer, t-decyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and the like can be used.

[0037] The rubber-modified styrene-based resin used in the substrate layer (A) of the present invention can be blended with an ultraviolet absorber and a light stabilizer for the purpose of improving light resistance. Specific examples of the ultraviolet absorber and light stabilizer are the same as the ultraviolet absorber and light stabilizer exemplified in the coating layer (B) described later. The UV absorber and the light stabilizer can be used alone or in combination, and the amount added is 0.01 for 100 parts by weight of the rubber-modified styrene-based resin as the sum of the UV absorber and the light stabilizer. ˜1.5 parts by weight is preferable, and 0.02 to 0.8 parts by weight is more preferable. The ratio of the UV absorber to the light stabilizer is preferably in the range of 1: 0 to 1: 3.

[0038] In the laminate of the present invention, the coating layer (B) is laminated on both sides or one side of the substrate layer (A).

The resin used for the coating layer (B) is a styrene resin or a (meth) acrylic ester-styrene resin from the viewpoint of adhesion to the rubber-modified styrene resin used for the substrate layer (A). It is fat.

[0039] The styrene-based resin used in the coating layer (B) of the present invention is styrene as a monomer unit. 50% by weight or more of the monomer, and even if the styrene monomer is substantially alone, the monomer copolymerizable with 50% by weight or more of the styrene monomer is 50% by weight or less. It may be a copolymer. Here, as the styrene monomer and the copolymerizable monomer, a styrene monomer and other copolymerizable monomers that form a continuous phase of the rubber-modified styrene resin described above. (Except (meth) acrylic acid ester) can be used, and may be used alone or in combination of two or more. As the styrene monomer, styrene is preferable.

[0040] The (meth) acrylic ester-styrene-based resin used for the coating layer (B) of the present invention is:

It is a copolymer of a (meth) acrylic acid ester monomer and a styrene monomer. Here, (meth) acrylic acid ester monomers include methyl methacrylate, ethyl acetate, butinole methacrylate, methinoare acrylate, ethino rare acrylate, butino rare acrylate, 2 —Ethylhexyl acrylate, cyclohexyl acrylate and the like. These may be used alone or in combination. In particular, methyl methacrylate and a mixture of methyl methacrylate and butyrate may be preferably used. Further, as the styrene monomer, the same styrene monomer that forms the continuous phase of the rubber-modified styrene resin described above can be used. Good. Styrene is preferred as the styrene monomer. Further, if necessary, other copolymerizable monomers may be used as long as they do not impair the object of the present invention. Here, the other copolymerizable monomers include other copolymerizable monomers (excluding (meth) acrylic acid esters) that form the continuous phase of the above rubber-modified styrene-based resin. Can be used alone or in combination of two or more.

[0041] Although not particularly limited, (meth) acrylic acid ester-based (meth) acrylic acid ester-based monomer used in the coating layer (B) of the present invention The proportion of the body is preferably 70% by weight or less to more than 0% by weight. More preferably, it is 55% by weight or less to more than 0% by weight. As the proportion of the (meth) acrylic acid ester monomer increases, scratch resistance and light resistance improve, which is preferable. However, when the proportion of the styrene monomer is less than 30% by weight, the laminate is obtained by coextrusion molding. The adhesion of the substrate layer (A) to the rubber-modified styrene-based resin , Because it tends to decrease.

[0042] The styrenic resin or (meth) acrylate ester styrene resin used in the coating layer (B) of the present invention has a rubbery polymer for the purpose of further improving impact resistance. A rubber-modified styrene resin or a rubber-modified (meth) acrylate monostyrene resin obtained by grafting a styrene monomer or a (meth) acrylic acid ester-styrene monomer on the surface can be used. Rubber-modified styrene-based resin or rubber-modified (meth) acrylic acid ester-styrene-based resin may be directly polymerized, or rubber-modified styrene-based resin or rubber-modified ) Acrylic ester-styrene resin may not contain a rubbery polymer, but may be a mixture of styrene resin or (meth) acrylic ester-styrene resin mixed and diluted. As the rubber-like polymer, the same rubber-like polymer that forms dispersed particles as the dispersed phase of the rubber-modified styrene-based resin used for the substrate layer (A) can be used. Styrenic resin or (meth) acrylate ester used in coating layer (B) The amount of rubbery polymer contained in styrene resin is either styrene resin or (meth) acrylate-styrene With respect to 100 parts by weight of rosin, 1 to LO parts by weight is preferable, and 2 to 6 parts by weight is more preferable.

[0043] In the resin used in the coating layer (B) of the present invention, an ultraviolet absorber can be added in order to prevent coloration due to ultraviolet rays generated from the light source lamp cover. . Examples of the ultraviolet absorber include 2- (5-methyl-2-hydroxyphenol) benzotriazole, 2- [2hydroxy-1,3,5-bis (α, a, monodimethylbenzyl) phenol] benzotriazole, 2— (3,5 di-t-amyl-2-hydroxyphenol) benzotriazole UV absorbers such as benzotriazole, 2-hydroxy-1-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone Benzophenone UV absorbers such as 2-hydroxy-4 n-otatoxiben zophenone, salicylic acid UV absorbers such as phenyl salicylate and 4 t-butyl phenyl salicylate, 2- (1-aryl alkydene) malonic acid ester UV Examples thereof include an absorber and an oxasulfide-based ultraviolet absorber. The amount of the ultraviolet absorber is 0.03 to 5 parts by weight, preferably 0.1 to 3 parts by weight, more preferably 100 parts by weight of the resin used in the coating layer (B). Is 0.2 to 2 parts by weight. If the amount of this UV absorber is less than 0.03 parts by weight, the light resistance of the laminate is not sufficient. In addition, if the amount exceeds 5 parts by weight, the UV absorber tends to bleed out on the surface of the laminate, which may impair the surface appearance of the laminate.

[0044] A light stabilizer can be added to the resin used in the coating layer (B) of the present invention for the purpose of further improving light resistance. Examples of the light stabilizer include hindered amine light stabilizers. Examples of hindered amine light stabilizers include bis (2, 2, 6, 6—tetramethyl-4-piperidyl) separate, N, N, 1bis (3-aminopropyl) ethylenediamine, 2, 4bis. [Ν butyl Ν— (1, 2, 2, 6, 6 pentamethyl-4-piperidyl) amino] —6, 1,3,5 triazine condensate. The light stabilizer can be used alone or in combination, and the addition amount is preferably 0.01 to 3 parts by weight, with respect to 100 parts by weight of the resin used in the coating layer (foam). More preferably, it is 0.1 to 2 parts by weight. When used in combination with a UV absorber, the ratio of the amount added to the UV absorber is preferably not more than 3 times (weight ratio) of the amount of UV absorber added, more preferably 0.5 to 2 times (weight ratio). ) Similarly to the ultraviolet absorber, the substrate layer (Α) may contain a light stabilizer.

[0045] A light diffusing agent can be added to the resin used in the coating layer (Β) of the present invention for the purpose of improving light diffusibility.

[0046] Here, as the light diffusing agent, either an inorganic or organic light diffusing agent can be used. For example, examples of the inorganic light diffusing agent include barium sulfate, calcium carbonate, aluminum hydroxide, calcium phosphate, and silica. Examples of the organic light diffusing agent include acrylate-based crosslinked particles, styrene-based crosslinked particles, methyl methacrylate-styrene copolymer crosslinked particles, and silicone-based crosslinked particles. These inorganic and organic light diffusing agents can be used alone or in combination.

[0047] The weight average particle diameter of the light diffusing agent is preferably 0.5 to 10 µm, more preferably 3 to 8 µm. The content of the light diffusing agent is preferably 0.1 to 5 parts by weight, more preferably 1 to 5 with respect to 100 parts by weight of styrene resin or (meth) acrylic ester-styrene resin. Parts by weight. The light diffusing agent may be added to either the coating layer (B) or the substrate layer (A), or may be added to both layers, but may be added to the coating layer (B). preferable.

[0048] For the purpose of preventing scratches, the light diffusing styrene-based resin laminate of the present invention can have a concavo-convex shape on the surface of the laminate to provide a matte surface. Concave and convex shape on the surface of the laminate Examples of the forming method include a method in which fine particles called a diffusing agent or a matting agent are added at the time of extrusion forming, and a method of forming unevenness on the surface of the laminated plate or a method of transferring the unevenness on a roll. When a diffusing agent or matting agent is added to form an uneven shape on the surface of the laminate, the diffusing agent or matting agent is added to one or both of the substrate layer (A) and the coating layer (B). However, it is preferable to add to the coating layer (B).

[0049] In the light diffusing styrene-based resin laminate of the present invention, from the viewpoint of production cost, the remaining end material obtained by taking out the laminate of a predetermined size from the laminate produced by extrusion molding or the like was crushed. You may recycle the product into new raw materials. The end material may be added to one or both of the substrate layer (A) and the coating layer (B), but is preferably added to the substrate layer (A).

[0050] The light-diffusing styrene-based resin laminate of the present invention can be improved in impact strength by adding polydimethylsiloxane, mineral oil, metal salts of higher fatty acids, and amides of higher fatty acids. .

[0051] Furthermore, the light diffusable styrene-based resin laminate of the present invention has various additives such as hindered phenol, phosphorus, and io, as long as the object of the present invention is not impaired, if necessary. Antioxidants, lubricants, antistatic agents, flame retardants, various dyes and pigments, fluorescent brighteners, and selective wavelength absorbers may be added.

[0052] The method for producing the light-diffusing styrene-based resin laminate of the present invention is not particularly limited, but for example, any stage before and after the recovery step during the production of the rubber-modified styrene-based resin. The ability to add an arbitrary additive within a range that does not impair the object of the present invention if necessary, or an optional additive within a range that does not impair the object of the present invention to a rubber-modified styrene-based resin, if necessary. After mixing by using a blender or a blender, the mixture is heated and melted with an extruder to prepare a resin composition for a substrate. Separately, styrene-based resin or (meth) acrylic acid ester, styrene-based resin, and if necessary Arbitrary additive in the range not impairing the object of the present invention is added in the same manner as described above to prepare a resin composition for coating. Then, these resin compositions are made into a laminate having the structure of the present invention by a known molding technique. For example, in addition to a method of separately obtaining a sheet-like molded body serving as a substrate layer and a film-shaped molded body serving as a coating layer from the above resin composition by a molding method such as a compression molding method or an extrusion molding method, and then bonding them together The above resin composition is obtained by a sheet extrusion molding machine having co-extrusion equipment. A method of extruding and integrally forming at the same time is used. A molding method using a coextrusion method is preferable from the viewpoint of production cost.

[0053] The thickness of the light-diffusing styrene-based resin laminate of the present invention is appropriately adjusted depending on the application, etc., but is usually 0.5 to 5 mm, preferably ί to 0.8 to 3 mm, more preferably ί to 1. 0 to 2.5 mm. If less than 5mm, the rigidity is insufficient, so it is not suitable.

[0054] The thickness of the coating layer (B) of the present invention is preferably in the ratio range of the total thickness of the coating layer (B) Z substrate layer (A) = 1 Z99 to lZ2.

[0055] The light diffusing styrene-based resin laminate of the present invention can be suitably used for liquid crystal display devices such as lighting fixtures, electric signboards, liquid crystal displays, and liquid crystal televisions. Among these, it is preferably used as a diffusion plate for a direct backlight of a liquid crystal display device.

Example

[0056] The present invention will be specifically described below. However, the present invention is not limited to these examples.

In the present invention, the following measurement method and evaluation method were used.

[0057] (1) Dispersed particle size m), particle size distribution

In C OULTER MULTISIZER II (trade name) manufactured by Beckman Coulter, Inc., equipped with a 30 μm aperture tube, put 2 to 5 rubber-modified styrene resin pellets in about 5 ml of dimethylformamide and about 2 to 5 Leave for a minute. Next, measure the dissolved dimethylformamide as an appropriate particle concentration, and obtain the volume-based median diameter. The particle size distribution was determined from the volume-based median diameter measured at the same time as the volume-based median diameter, as the volume-based median diameter and the Z-number-based median diameter.

[0058] (2) rubber-like polymer content (wt ^_0/0)

0.25 g of rubber-modified styrene resin is dissolved in 50 ml of black mouth form, and after adding iodine monochloride to react the double bond in the rubber component, potassium iodide is added and the remaining iodine monochloride is added. The content of the rubbery polymer in the rubber-modified styrene-based resin was measured by using the iodine monochloride method in which T was changed to iodine and back titrated with sodium thiosulfate.

[0059] (3) methyl E chill ketone insolubles (wt ^_0/0) Rubber-modified styrenic resin lg is precisely weighed (Wl (g)), 20 ml of methyl ethyl ketone is squeezed, shaken at 23 ° C for 2 hours, and then centrifuged (hiacac manufactured by Hitachi, Ltd.) Name) Centrifuge with CR-20 (rotor: R20A2)) at 10 ° C or less and 20000 rpm for 60 minutes. Decant the supernatant to remove insolubles. Next, vacuum-dry for 60 minutes under conditions of 160 ° C and 20mmHg or less, cool to room temperature in a desiccator, and accurately weigh the insoluble matter (W2 (g)). A methyl ethyl ketone insoluble content is calculated | required by a following formula.

Methyl ethyl ketone insoluble matter (wt%) = (W2 (g) / Wl (g)) X 100

[0060] (4) Swelling index for toluene

23. Weigh accurately rubber-modified styrenic resin lg (W3 (g)) and add 20 ml of toluene23. After shaking at C for 2 hours, centrifuge for 60 minutes at 20000 rpm at 10 ° C or less in a centrifuge (hiac (trade name) CR-20 (Hitachi: R20A2) manufactured by Hitachi, Ltd.)). Decant the supernatant and remove the weight of the insoluble matter containing toluene (W4 (g)). Next, vacuum-dry for 60 minutes at 160 ° C and 20mmHg or less, cool to room temperature in a desiccator, and weigh the insoluble matter precisely (W5 (g)). The swelling index for toluene is obtained by the following formula.

Swelling index for toluene = W4 (g) / W5 (g)

[0061] (5) Value of (weight of styrene-based polymer Z weight of rubber-like polymer) in methylethylketone insoluble matter (hereinafter abbreviated as PSZRu ratio of dispersed phase).

The PSZRu ratio of the dispersed phase in the rubber-modified styrenic resin was determined by the following formula.

PSZRu ratio of dispersed phase = (methylethylketone insoluble matter rubbery polymer content) Z rubbery polymer content

[0062] (6) Total light transmittance, yellowness (yellow index)

Based on JIS K7105, total light transmittance was measured using a color difference turbidity measuring instrument COH300A (trade name) manufactured by Nippon Denshoku Co., Ltd. At the same time, the yellow index was measured.

[0063] (7) Light diffusivity (%)

Using a go-off optometer manufactured by Optech Co., Ltd., the light that is incident on the specimen in the direction perpendicular to the white light source and transmitted to the opposite side of the specimen is placed in the range of 0 ° to 70 °. The luminance was measured and calculated by the following formula.

Light diffusivity (%) = (20 ° brightness + 70 ° brightness) ÷ (5 ° brightness X2) X100

[0064] (9) DuPont impact strength (kg · cm)

In accordance with JIS K5400, the 50% fracture energy was measured under the conditions of shooting type diameter 3Z8 inches and cradle diameter 1Z2 inches.

[0065] (10) Light resistance (ΔE)

Suga Test Instruments Co., Ltd. Sunshine Weather Meter Model S80BBR, with black panel temperature 63 ° C, humidity 50% RH, rainfall interval Rainfall 18 minutes Z cycle 120 minutes

After exposure for 300 hours, the color difference ΔΕ of transmission was measured with Nippon Denshoku Industries Co., Ltd. color difference and turbidity measuring instrument COH-300A to evaluate the light resistance.

[0066] The rubber-modified styrenic resin used in Examples and Comparative Examples was produced by the following method.

[0067] (Production of rubber-modified styrene-based resin HI)

A 1.8 liter tower reactor equipped with a stirrer and jacket as the first stream (No.

The following raw material solution (a) was continuously fed to 1 reactor) with 1.5 liters of ZHr.

[0068] As the rubber-like polymer, 5 wt ^_0/0 styrene solution viscosity of 25 ° C is using Roshi scan polybutadiene rubber 35 Senchiboizu, to prepare a raw material solution (a) of the following composition. Raw material solution (a) 2 JJ t s- s Is &&&&& a &&&& Rubber-like polymer 1 2. 5 Quantity Quantity Quantity Quantity Quantity Styrene 74.5 parts Ethylbenzene 1 3. 0 α-Methylstyrene Dimer 0 . 26

1,1-bis (t-butylperoxy) cyclohexane 0.05 05 tert-butyl peroxide 0.02 The number of stirring of the first reactor was lOOrpm, and the temperature was controlled at 104 ° C. The solid content concentration at the outlet of the first reactor was 21.0% by weight. As a second flow, the following raw material solution (b) was continuously fed to a 6.2 liter tower reactor (second reactor) equipped with a stirrer and a jacket at 1.5 liter ZHr. Raw material solution (b)

Styrene 95.0 Ethylbenzene 5.0

1, 1-bis (t-butylperoxy) cyclohexane 0. 01 [0070] The number of stirring in the second reactor was llOrpm, and the temperature was controlled at 123 to 132 ° C. The solid concentration at the outlet of the second reactor was 45.2% by weight. These first flow and second flow have a capacity of 0.5 liter, the distance between the stirring blade tip and the mixer wall is 2 mm, and a 19-stage stirring rod is attached in the axial direction, The pins were introduced into the mixing stirrer, which is located between the stirring rods, on the machine wall, and mixed at a stirring speed of 400 rpm. Next, the mixture was fed into a 6.2-liter column reactor (third reactor) equipped with a stirrer and a jacket, and polymerized at a temperature of 118 to 123 ° C. for 2.1 hours. Furthermore, it was fed into a 6.2 liter tower reactor (fourth reactor) equipped with a stirrer and a jacket and polymerized at a temperature of 120 to 130 ° C. for 2.1 hours. The resulting polymerization solution was continuously supplied to the devolatilizing extruder with a two-stage vent, the extruder temperature was 240 ° C, the vacuum degree of the first and second stage vents was _{25 torr} , unreacted monomer and solvent The rubber-modified styrenic resin HI was obtained.

[0071] (Production of rubber-modified styrene-based resin H2)

The following raw material solution (a) was continuously fed in 1.5 liter ZHr to a 1.8 liter tower reactor (first reactor) having a stirrer and a jacket as the first flow.

[0072] As the rubber-like polymer, 5 wt ^_0/0 styrene solution viscosity of 25 ° C is using Roshi scan polybutadiene rubber 35 Senchiboizu, to prepare a raw material solution (a) of the following composition. Raw material solution (a)

Rubbery polymer 1 1.5 Styrene 7 5.5 5 && Ethylbenzene 1 3.0 Quantity Quantity Quantity Quantity α-Methylole styrene dimer 0.6 6

1, 1 bis (t-butylperoxy) cyclohexane 0.05 g tert-butylenoperoxide 0.0 1

[0073] The number of stirring in the first reactor was lOOrpm, and the temperature was controlled at 108 ° C. The solid content concentration at the outlet of the first reactor was 22.0% by weight. The second stream was equipped with a stirrer and a jacket. 6. The following raw material solution (b) was continuously fed to a 2-liter tower reactor (second reactor) at 1.5 liter ZHr. . Raw material solution (b)

Styrene 9 5 0 Ethenolebenzene 5 0

1, 1 _bis (tert-butyloxy) cyclohexane 0 0 [0074] The number of stirring in the second reactor was llOrpm, and the temperature was controlled at 123 to 132 ° C. The solid concentration at the outlet of the second reactor was 45.1% by weight. After the stirring mixer, the rubber was modified in the same manner as the rubber-modified styrene-based resin HI, except that the temperature of the third reactor was 117 to 123 ° C and the temperature of the fourth reactor was 123 to 133 ° C. Styrenic resin H2 was obtained.

[0075] (Production of rubber-modified styrene-based resin H3)

As the rubbery polymer, 5 wt ^_0/0 styrene solution viscosity of 25 ° C is using low cis polybutadiene rubber 170 Senchiboizu, to prepare a raw material solution having the following composition. Rubbery polymer 3

Styrene 8 6

Ethylbenzene 1 0

α-Methylole styrene dimer 0

1, 1 bis (t_butylperoxy) cyclohexane 0

G t butyl peroxide 0

[0076] The raw material solution was continuously supplied at a rate of 2.4 liters Zhr to a polymerization apparatus in which three column reactors equipped with a stirrer (each internal volume 6.2 liters) were connected in series. The stirring speed of the first reactor was set to 90 rpm. Polymerization temperature: 1st reactor 122-131 ° C for 2.6 hours, 2nd reactor 135-145 ° C for 2.6 hours, 3rd reactor 145-155 ° C for 2.6 hours Carried out. The obtained polymerization solution is continuously fed to a devolatilizing extruder with a two-stage vent, the extruder temperature is 230 ° C, the vacuum of the first and second vents is 25 torr, unreacted monomer and solvent 32 s s Ϊ Ϊ ί ί 11 量量量量量量ゴムゴムゴムゴム剖ゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴムゴム 이 ゴムβ β β--.

[0077] (Production of rubber-modified styrene resin H4)

The following raw material solution (a) was continuously fed in 2.0 liter ZHr to a 2.4 liter tower reactor (first reactor) equipped with a stirrer and a jacket as the first flow. As a rubbery polymer, a low-cis polybutaene rubber having a viscosity of 35 centipoise at 25 ° C. and a 5 wt% styrene solution was used to prepare a raw material solution (a) having the following composition. Raw material solution (a)

Polybutadiene rubber 9.6

Styrene 7 5.4

Yet / Lebenzene 1 5. 0

α-Methylstyrene dimer 0.0 7 5

1,1-bis (t-butylperoxy) cyclohexane 0.0 7 5 [0078] The number of stirring in the first reactor was lOOrpm, and the temperature was controlled at 97 ° C. The solid content at the outlet of the first reactor was 16.0% by weight. The following raw material solution (b) was continuously fed in 1.0 liter ZHr to a 6.2 liter tower reactor (second reactor) equipped with a stirrer and a jacket as the second flow. Raw material solution (b)

Styrene 89.7 parts by weight Ethylbenzene 1 0 '3 parts by weight

[0079] The rotation speed of the second reactor was llOrpm, and the temperature was controlled at 130-140 ° C. The solid concentration at the outlet of the second reactor was 50.0% by weight. The first flow and the second flow have a capacity of 0.5 liter, the clearance between the tip of the stirring blade and the mixer wall is 5 mm, and a 15-stage stirring rod is attached in the axial direction. A heat transfer tube was introduced into the wall into the mixing stirrer that was placed between the stirring rods, and mixed at a rotation speed of 200 rpm. Next, the mixture was fed into a 6.2 liter tower reactor (third reactor) equipped with a stirrer and a jacket, and polymerized at a temperature of 112 to 120 ° C for 2.1 hours. Further, it was fed into a 6.2 liter tower reactor (fourth reactor) equipped with a stirrer and a jacket, and polymerized at a temperature of 140 to 155 ° C. for 2.1 hours. The resulting polymerization solution was continuously supplied to the devolatilizing extruder with a two-stage vent, the extruder temperature was 230 ° C, the vacuum of the first-stage vent and the second-stage vent was 25 torr, and unreacted monomer and solvent were removed. It was recovered and operated according to Example 3 of JP2003-2937 to obtain a rubber-modified styrene-based resin H4.

[0080] (GP polystyrene resin G1)

Weight average molecular weight Mw 312,000, number average molecular weight Mnll. 70,000, molecular weight distribution MwZM n 2.7, MFR (200 ° C—5 kg) l.

[0081] (Methyl methacrylate-styrene copolymer resin Ml)

Methyl methacrylate component content 49% by weight, styrene component content 51% by weight, weight average molecular weight Mw 130,000, number average molecular weight Mn720,000, molecular weight distribution MwZMn1.9, MFR (200 ° C — 5 kg) l. 5 g ZlO of methyl methacrylate-styrene copolymer resin was used.

[0082] (Light diffusing agent K1)

Polymethyl methacrylate cross-linked particles (manufactured by Sekisui Plastics Co., Ltd., trade name: Techpolymer) MBX-5, refractive index 1.49, weight average particle size 5 m) was used.

[0083] (UV absorber UVA)

2- (5-Methyl-2-hydroxyphenol) benzotriazole (Tinoku 'Specialty' Chemicals Co., Ltd. Tinuvin P) was used.

[0084] (Light stabilizer HALS)

Bis (2, 2, 6, 6-tetramethyl-4-piperidyl) Sepacate (Sankyo Corporation Sanol LS

-770)

[0085] [Production and analysis of resin used for substrate layer (A)]

Resin used for substrate layer (A) Al, A2, A4, A5 are rubber-modified styrene-based resin HI to 4 pellets, A3, A6-8 are rubber-modified styrene-based S SHI, H3 H4, GP polystyrene resin G 1 and light diffusing agent K1 were mixed in the composition shown in Table 1 and melt-kneaded using a 30 mm twin screw extruder. A8 was removed from the obtained pellets, and the rubbery polymer content, dispersed particle size, methyl ethyl ketone insoluble content, and swelling index with respect to toluene were measured, and the PSZRu ratio of the dispersed phase was calculated from the measurement results. The results are shown in Table 1.

[0086] [Preparation of resin used for coating layer (B)]

It mixed with the compounding composition shown in Table 2, and melt-kneaded with the 30-mm twin-screw extruder, and coating layer (B) resin B1-B5 was obtained.

[Examples 1-7, Comparative Examples 1-5]

In the layer configuration shown in Table 3, using a multilayer sheet extrusion apparatus with the following configuration, the resin used for the substrate layer (A) is the intermediate layer, and the resin used for the coating layer (B) is the surface layer (both sides). Coextruded sheet molding was carried out so that

[0088] Multi-layer sheet extrusion molding machine

Extruder 1: Single screw screw diameter 40mm

Extruder 2: Single screw screw diameter 30mm

Feed block: 2 types, 3 layers, dice: T-die

[0089] The resin used for the substrate layer (A) is the extruder 1, and the resin used for the coating layer (B) is the extruder 2. The temperature of the extruder and the die is 210 to 230 ° C. This was carried out to produce a laminate having a thickness of 2 mm (intermediate layer: 1.9 mm, surface layer (both sides): 0.05 mm). Cut a specimen from the resulting laminate. The total light transmittance, light diffusivity, yellowness (yellow index), Dupont impact strength, and light resistance (ΔΕ) were measured. The results are shown in Table 3.

[Examples 1 to 6]

Examples 1 to 6 are excellent in total light transmittance, light diffusibility, impact resistance, and light resistance with small yellowness of transmitted light.

[Example 7]

Example 7 is excellent in total light transmittance, light diffusibility, and impact resistance in which the yellowness of transmitted light is small.

[Comparative Examples 1 to 4]

Comparative Examples 1 to 4 are inferior in yellowness of transmitted light. In addition, Comparative Example 3 is inferior in light diffusibility.

[Comparative Example 5]

In Comparative Example 5, the yellowness of the transmitted light is small, but the impact resistance is poor.

[0094] [Table 1]

table 1

Table 2

^ 0095 Table 3

Industrial applicability

[0097] The light-diffusing styrene-based resin laminate of the present invention can be suitably used as a diffusing plate for liquid crystal display devices such as lighting fixtures, electric signs, liquid crystal displays, and liquid crystal televisions. Among these, it is suitably used as a light diffusing plate for a direct backlight of a liquid crystal display device. Brief Description of Drawings

FIG. 1 is a schematic diagram for explaining a sea-island structure of a cross section of rubbery polymer particles. Here, 1 is a styrenic polymer serving as a matrix, 2 is a rubbery polymer dispersed in the matrix, and 3 is a styrene polymer encapsulated in the rubbery polymer.

Claims

The scope of the claims

[1] It includes a styrenic polymer forming a matrix and rubber-like polymer particles dispersed in islands in the matrix, and the cross-section of the rubber-like polymer particles includes the styrenic polymer particles. It is a rubber-modified styrene-based resin that forms a sea-island structure and has a strength of 1-10% by weight of a rubbery polymer and 99-90% by weight of a styrene-based polymer. The diameter is 1.0 to 5.0 m, and the value of (weight of styrene polymer Z weight of rubber-like polymer) in the methylethylketone insoluble content of rubber-modified styrene-based resin is 0.5 to 1. A substrate layer (A) comprising the rubber-modified styrenic resin in the range of 5, and

A coating layer (B) comprising styrene-based resin or (meth) acrylic ester-styrene-based resin on both surfaces or one surface of the substrate layer (A)

A light-diffusing styrene-based resin laminate comprising:

2. The light diffusing styrene according to claim 1, wherein the rubber-modified styrene-based rubber-like polymer particles used in the substrate layer (A) have a particle size distribution in the range of 1.0 to 1.6. System resin laminate

[3] The light-diffusing styrenic resin according to claim 1 or 2, wherein the rubber-modified styrenic resin used in the substrate layer (A) has a swelling index with respect to toluene of 5.0 to 10.0.榭脂层层板.

[4] The styrene-based resin or (meth) acrylate ester-based resin used in the coating layer (B) is a rubber-modified styrene resin or rubber-modified (meth) acrylate-ester resin. The light-diffusing styrene-based resin laminate according to any one of claims 1 to 3.

[5] The method according to any one of claims 1 to 4, wherein the coating layer (B) contains 0.03 to 5 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the resin used in the coating layer (B). The light diffusable styrene-based resin laminate according to claim 1.

[6] A light diffusing plate for backlight comprising the light diffusing styrene-based resin laminate according to any one of claims 1 to 5.