TWI458774B - Styrene-based resin composition and molded body - Google Patents

Description

Styrene resin composition and formed body

The present invention relates to a styrene resin composition and a molded body formed using the same.

A screen lens for a transmissive screen or the like for projecting television represents a portrait on which a projected image is placed. This screen lens is generally formed of a lens molded body such as a lenticular lens or a fresnel ear lens, which is expected to be bright and has a wide viewing angle. Among these lens molded bodies, methacrylic resins which are excellent in transparency, light resistance, scratch resistance, and moldability are widely used, and these molded articles are generally formed by press molding, extrusion molding, casting molding, and the like. Molding is performed by injection molding or the like.

The methacrylic resin used in this screen lens has a high water absorption rate, and thus the molded body formed therefrom easily undergoes dimensional change via water absorption. In order to solve this problem, it has been disclosed that a mixture of an aromatic vinyl monomer, a (meth) acrylate monomer, and a polyfunctional unsaturated monomer is used to dissolve a styrene-diene copolymer. A method of obtaining a Fresnel lens after polymerizing a resin (Patent Document 1).

Further, methacrylic resin is also used for the diffusing plate forming material of the liquid crystal TV, and this also has the same problem.

Patent Document 1: Japanese Patent Publication No. 5-341101

An object of the present invention is to provide a molded article of a resin composition and a resin composition thereof which can obtain a molded article having excellent dimensional stability, light resistance, optical properties, and thermal stability.

In order to solve the above problems, the inventors of the present invention have found that a copolymer containing a styrene monomer unit and a methacrylic monomer unit as a main component, and a specific unmelted compound or polyorganosiloxane are found. The crosslinked particles and the styrene resin composition of the specific light stabilizer can be obtained by injection molding or extrusion molding to obtain a molded body having good dimensional stability, light resistance, light diffusibility, and thermal stability. this invention.

That is, the present invention has the following gist.

1. 100 parts by mass of a styrene copolymer composed of 90 to 99% by mass of a styrene monomer unit and 10 to 1% by mass of a (meth)acrylic monomer unit, and 1 to 10 An unmelted compound having a refractive index difference of 0.05 to 0.15 and an average particle diameter of 2 to 10 μm, or 0.5 to 2.5 parts by mass of a polyorganooxynonane having a particle diameter of 1 to 10 μm. A styrene resin composition comprising crosslinked particles and 0.1 to 2 parts by mass of a hindered amine compound and 0.1 to 2 parts by mass of a benzotriazole compound.

2. The unmelted compound is a styrene resin composition as described above in the above-mentioned 1 containing a crosslinked copolymer containing a (meth) acrylate monomer as a monomer unit.

3. The unmelted compound is a styrene resin composition as described above in the above-mentioned 1 containing a crosslinked copolymer of methyl methacrylate and n-butyl acrylate.

4. The hindered amine compound is a styrene resin composition according to any one of the above 1 to 3 of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

5. The benzotriazole-based compound is any of the above 1 to 4 of 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol. The styrene resin composition of the item.

A styrene-based resin composition according to any one of the above 1 to 5, which further contains 0.005 to 0.5 part by mass of the benzoxazole-based compound, in an amount of from 0.005 to 0.5 parts by mass per 100 parts by mass of the styrene-based copolymer.

7. The benzoxazole-based compound is a styrene-based resin composition contained in the above 6 of 2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole).

8. The styrene resin composition further contains 0.1 to 3 parts by mass of an amine-based surfactant, an anionic surfactant, and a non-amine nonionic surfactant for 100 parts by mass of the styrene copolymer. The styrene resin composition according to any one of the above 1 to 7.

9. The amine-based surfactant is a styrene-based resin composition contained in the above 8 of N-hydroxyethyl-N-(2-hydroxyalkyl)amine.

10. The mixing ratio of the anionic surfactant and the non-amine nonionic surfactant is the above 8 of the anionic surfactant/non-amine nonionic surfactant = 0.5/99.5 to 15/85 (mass ratio) A styrene-based resin composition.

11. The anionic surfactant is a styrene resin composition of the above 8 or 10 in which the organic sulfonic acid metal salt having 10 to 14 carbon atoms and the non-amine nonionic surfactant is the glycerin fatty acid ester.

12. The molded body obtained by the styrene resin composition according to any one of the above 1 to 11, which has a thickness of 1 to 7 mm.

13. The molded body is a molded body carried out in the above 12 of the injection molded body.

14. The molded body is a molded body contained in the above 12 of the extruded body.

A light-diffusing sheet using the molded article according to any one of the above items 12 to 14.

The molded article formed from the styrene resin composition of the present invention has excellent light diffusibility, dimensional stability, light resistance, thermal stability, and brightness.

[Best form of invention implementation]

Hereinafter, the detailed description of the present invention will be made.

Examples of the styrene monomer used in the present invention include styrene, α-methylstyrene, p-methylstyrene, p-t-butylstyrene, etc., preferably styrene. .

Examples of the (meth)acrylic monomer used in the present invention include acrylic acid, methacrylic acid, and ethacrylic acid, and methacrylic acid is preferred.

The styrene copolymer is composed of 90 to 99% by mass of a styrene monomer unit, preferably 91 to 97% by mass and 10 to 1% by mass of a (meth)acrylic monomer unit, more preferably 9 ~3% by mass. When the styrene monomer unit exceeds 99% by mass, the thermal stability of the obtained molded body is lowered, and if it is less than 90% by mass, the molded body is deformed by moisture absorption.

The styrene-based copolymer may contain, in addition to the above styrene-based monomer and (meth)acryl-based monomer, a vinyl monomer copolymerizable therewith, and a styrene-based monomer and a methacrylate single When the total amount is 100 parts by mass, the amount is preferably 10 parts by mass or less. Examples of the vinyl monomer which can be copolymerized are, for example, a vinyl cyanide monomer such as acrylonitrile or methacrylonitrile; and an unsaturated acid such as acrylic acid, maleic anhydride, maleic acid, itaconic acid or itaconic anhydride. Carboxylic acid monomer; maleic anhydride imide, N-methyl maleic anhydride imide, N-phenyl maleic anhydride, and the like. These may be used alone or in combination of two or more.

The styrene-based resin composition of the present invention is preferably contained in an amount of 1 to 10 parts by mass, preferably 2 to 9 parts by mass, per 100 parts by mass of the styrene-based copolymer. When the content of the unmelted compound is less than 1 part by mass, the haze and the diffusivity are small, and the light diffusibility is lowered. On the other hand, when it exceeds 10 parts by mass, the total light transmittance is lowered.

The unmelted compound is not particularly limited, and generally contains a crosslinked copolymer of a (meth) acrylate monomer as a monomer unit, and specifically, for example, contains methyl methacrylate or ethyl methacrylate. A crosslinked copolymer of a monomer such as methyl acrylate or n-butyl acrylate, and preferably a crosslinked copolymer containing methyl methacrylate and n-butyl acrylate.

The unmelted compound is preferably a compound having a melting point or a softening point at an atmosphere of 1 atm. at 200 ° C or higher. When the melting point and the softening point are less than 200 ° C, the compound is easily melted during melt-kneading with the styrene-based polymer or during extrusion molding or injection molding of the styrene-based resin composition, and the compound is not easily maintained. Optical properties. The difference in refractive index between the unmelted compound and the styrene-based copolymer is 0.05 to 0.15, preferably 0.07 to 0.13, and the average particle diameter is 2 to 10 μm, preferably 3 to 9 μm. When the refractive index is less than 0.05, the haze and the diffusivity of the obtained molded article become small, and the light diffusibility is lowered. On the other hand, when the refractive index exceeds 0.15, the total light transmittance is lowered. Further, when the average particle diameter is less than 2 μm, the total light transmittance of the obtained molded body is lowered, whereas when it exceeds 10 μm, the haze and the light diffusivity are lowered.

Further, the styrene-based resin composition of the present invention contains 0.5 to 2.5 parts by mass of the polyorganosiloxane cross-linked particles, preferably 0.8 to 2.2 parts by mass, per 100 parts by mass of the styrene-based copolymer. When the content of the crosslinked particles of the polyorganosiloxane is less than 0.5 parts by mass, the haze and the diffusivity are small, and the light diffusibility is lowered. On the other hand, when the amount exceeds 2.5 parts by mass, the total light transmittance is lowered.

Further, the average particle size of the unmelted compound and the polyorganosiloxane cross-linked particles utilizes Kurt. The value obtained by the measurement was measured by a composite classifier (manufactured by Beckman Coulter Co., Ltd.). The measurement method is carried out by laser refracting light diffusion method. Water is used in the solvent, a homogenizer is used for 1 minute, and an output power of 200 W is added to disperse the sample, and the concentration of PIDS (polarization intensity differential dispersion) is adjusted to 45~ 55%, the refractive index of water was made 1.33, and the measurement was performed, and the volume distribution was calculated as the average particle diameter.

The styrene-based resin composition of the present invention must contain 0.1 to 2 parts by mass of the hindered amine compound, preferably 0.2 to 1.2 parts by mass, and 0.1 to 2 parts by mass, per 100 parts by mass of the styrene-based copolymer. The benzotriazole-based compound is preferably 0.2 to 1.2 parts by mass.

When the hindered amine compound or the benzotriazole compound is less than 0.1 part by mass, the light resistance is insufficient, and if it exceeds 2 parts by mass, the yellowness of the obtained light-diffusing sheet is not preferable.

The hindered amine compound is an amine light stabilizer, such as: bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperazinyl) sebacate, bis ( 1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1 dimethylethyl)-4-hydroxyphenyl]methyl]butylpropane Diester, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidin Examples of the pyridine phthalic acid ester and the bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate may be used singly or in combination of two or more.

Further, the benzotriazole-based compound is an ultraviolet absorber such as 2-(2H-benzotriazol-2-yl)-p-cresol or 2-(2H-benzotriazol-2-yl)- 4-6-bis(1-methyl-1-phenylethyl)phenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl]-6-(t -butyl)phenol, 2,4-di-t-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2-(2H-benzotriazol-2-yl)-4 , 6-di-t-pentylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, etc. They may be used alone or in combination of two or more.

Further, in the resin composition of the present invention, the fluorinated brightener benzoxazole compound further containing 0.0005 to 0.5 part by mass of the coloring agent per 100 parts by mass of the styrene-based copolymer, more preferably 0.0008~ 0.2 parts by mass. When the content of the benzoxazole-based compound is 0.0005 parts by mass or more, the yellowness of the obtained sheet is lowered as compared with less than 0.0005 parts by mass, and not only the appearance is improved, but also the total light transmittance of the obtained sheet is improved. Further, when the amount is 0.5 parts by mass or less, the light resistance of the obtained multilayer sheet is further improved, and more preferably it is more than 0.5 parts by mass.

Examples of benzoxazole compounds are: 2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole), 2,5-thiophenediyl (5-t-butyl) a mixture of 10% of 1,3-benzoxazole) and 10% of dicyclohexyl phthalate, 4,4'-bis(benzoxazol-2-yl)anthracene, etc. Can be used alone or in combination.

In the sheet of the present invention, when the antistatic property is imparted for dustproof, further, 0.1 to 3 parts by mass of the amine-based surfactant, or an anionic surfactant, and the non-amine non-containing are contained in 100 parts by mass of the styrene-based copolymer. The ion-based surfactant is more preferably contained in an amount of 0.1 to 2.5 parts by mass. When the amine-based surfactant, the anionic surfactant, and the non-amine nonionic surfactant are 0.1 parts by mass or more, a sufficient antistatic effect can be obtained as compared with less than 0.1 part by mass. On the other hand, when the amount exceeds 3 parts by mass, the resulting sheet is more likely to cause discoloration than 3 parts by mass or less.

As an amine surfactant, such as: alkyl diethanolamine, polyethylene oxide alkylamine, alkyl diethanol amine, polyethylene oxide alkylamine, N-hydroxyethyl-N- (2 Examples of the -hydroxyalkylamines and the like may be used alone or in combination of two or more.

Examples of the anionic surfactant are, for example, an organic sulfonic acid metal salt, and specific examples thereof include sodium alkylsulfonate, lithium alkylsulfonate, sodium alkylbenzenesulfonate, and lithium alkylbenzenesulfonate. Among them, sodium alkyl sulfonate is preferred as the user. More preferably, it is a sodium alkylsulfonate having 10 to 14 carbon atoms. These may be used alone or in combination of two or more.

Examples of non-amine nonionic surfactants include polyethylene oxide alkyl ethers, polyethylene oxide fatty acid esters, and glycerin fatty acid esters. Among them, glycerin fatty acid ester is preferred as the user. These may be used alone or in combination of two or more.

When the anionic surfactant and the non-amine nonionic surfactant are used in combination, the anionic surfactant/non-amine nonionic surfactant is 0.5/99.5 to 15/85 (mass ratio), preferably After using the ratio of 5/95~12/88 (mass ratio), good antistatic performance can be obtained.

The method for producing the styrene-based copolymer of the present invention is not particularly limited, and a bulk polymerization method, a suspension polymerization method, a solution polymerization method, or an emulsion polymerization method can be generally used.

The method for blending the unmelted compound or the polyorganosiloxane cross-linked particles is not particularly limited, and is generally a method in which a styrene-based copolymer is blended before, during, and after polymerization, and is mixed with a styrene-based copolymer. The method of cooperation, etc.

When the styrene-based copolymer is granulated and then melt-mixed with the unmelted compound or the polyorganosiloxane cross-linked particles, the mixing method thereof is not particularly limited, and generally, for example, a high-speed agitating mixer and a drum are used. After mixing and mixing by a known mixer such as a mixer or the like, the mixture is melt-kneaded by using a squeezer such as a uniaxial extruder or a twin-screw extruder, and then uniformly mixed.

Further, in the styrene-based copolymer, the unmelted compound or the polyorganosiloxane cross-linked particles are placed in a high-concentration mixture of a high concentration, and the high-concentration mixture is mixed with styrene during injection/extrusion molding. After the copolymer is subjected to dry mixing, the content of the unmelted compound or the polyorganosiloxane cross-linked particles can be used as a raw material after the content of the cross-linked particles is adjusted to a predetermined concentration.

The styrene resin composition of the present invention may be blended with an additive as necessary. For example, in order to improve fluidity and mold release, it can be blended with plasticizers, lubricants, and polyoxygenated oils. In addition, in order to further improve the thermal stability, a heat stabilizer can be blended.

The molded article of the present invention has a thickness of 1 to 7 mm, preferably 1.3 to 4 mm. When it is less than 1 mm or exceeds 7 mm, good light diffusibility cannot be obtained.

[Examples]

In the following, the invention will be specifically described by way of examples, but the invention is not limited thereto.

[Manufacture of styrene copolymer]

The tank used for the production is such that the first complete mixing tank having a volume of about 5 L and the second complete mixing tank having a volume of about 15 L are connected until the first devolatilization tank of the preheater is connected in series with the second devolatilization tank. After the composition. 15 masses for 100 parts by mass of 85 parts by mass of a monomer solution containing 0.1 ppm of styrene of 4-t-butylcatechol and 15% by mass of methacrylic acid obtained in Reference Example Parts of ethylbenzene, 0.01 parts by mass of t-butylperoxyisopropylmonocarbonate, and 0.2 parts by mass of 2,4-diphenyl-4-methyl-1-pentene are mixed and used as a raw material. Solution. This raw material solution was supplied at 6.0 kg per hour to the first complete mixing tank controlled at 135 °C. The conversion rate at the outlet of the first complete mixing tank was 28% by mass. Then, it was continuously taken out from the first complete mixing tank, and then supplied to the second complete mixing tank controlled at 135 °C. The conversion rate at the outlet of the second complete mixing tank was 63% by mass. Further, the mixture was continuously taken out from the second complete mixing tank, and after heating in the preheater, it was introduced into a first devolatilization tank controlled at 67 kPa and 160 °C. Further, it was taken out continuously from the first devolatilization tank, heated in a preheater, and introduced into a second devolatilization tank controlled at 1.3 kPa and 230 ° C, and then the monomer was removed. This was extruded into a strand shape to obtain a pellet-shaped styrene-based copolymer (A-1).

A styrene-based copolymer (A-2) was obtained in the same manner as in (A-1) except that a monomer solution composed of 92% by mass of styrene and 8% by mass of methacrylic acid was used.

A styrene-based copolymer (A-3) was obtained in the same manner as in (A-1) except that a monomer solution composed of 96% by mass of styrene and 4% by mass of methacrylic acid was used.

A styrene-based copolymer (A-4) was obtained in the same manner as in (A-1) except that a monomer solution composed of 99.5% by mass of styrene and 0.5% by mass of methacrylic acid was used.

[Polyorganomethoxyoxane crosslinked particles (B) of unmelted compound]

As the unmelted compound, the polyorganooxane crosslinked particle system is a tospearl 120 (average particle diameter 2 μm, refractive index 1.420) (B-1), tospearl 2000B (average particle diameter 2 μm, refractive index 1.420) (B-1) prepared by GE Toshiba Polyoxane Co., Ltd. Particle size: 6 μm, refractive index: 1.420) (B-2), tospearl 3120 (average particle diameter: 12 μm, refractive index: 1.420) (B-3).

[Manufacture of MMA-nBA Copolymerization Crosslinked Particles (C) of Unmelted Compound]

20 parts by mass of methyl methacrylate, 80 parts by mass of n-butyl acrylate, and 5 parts by mass of a crosslinking agent were placed in an autoclave to which a stirrer was applied. Divinylbenzene, 0.2 parts by mass of a benzamidine peroxide of a polymerization initiator, 0.001 parts by mass of a suspension stabilizer sodium laurylbenzenesulfonate, and 0.5 parts by mass of a third calcium phosphate, 200 parts by mass of pure water at a temperature of 95 At ° C, polymerization was carried out for 6 hours, and at a temperature of 130 ° C, polymerization was carried out for 2 hours. After completion of the reaction, the mixture was washed, dehydrated, and dried to obtain crosslinked particles (C). The crosslinked particles (C) had an average particle diameter of 4 μm and a refractive index of 1.460.

[Manufacture of styrene-MMA crosslinked particles (D) of unmelted compound]

60 parts by mass of styrene, 40 parts by mass of methyl methacrylate, 5 parts by mass of a crosslinking agent of divinylbenzene, and 0.2 parts by mass of a polymerization initiator of benzamidine peroxide are placed in an autoclave to which a stirrer is applied. 0.001 parts by mass of a suspension stabilizer sodium laurylbenzenesulfonate, and 0.5 parts by mass of calcium triphosphate and 200 parts by mass of pure water were polymerized at a temperature of 95 ° C for 6 hours, and further polymerized at a temperature of 130 ° C for 2 hours. After completion of the reaction, washing, dehydration, and drying were carried out to obtain crosslinked particles (D). The crosslinked particles had an average particle diameter of 8 μm and a refractive index of 1.555.

[Manufacture of PMMA crosslinked particles (E) of unmelted compound]

100 parts by mass of methyl methacrylate, 5 parts by mass of a crosslinking agent of divinylbenzene, 0.2 parts by mass of a polymerization initiator of benzamidine peroxide, and 0.001 parts by mass of a suspension are placed in an autoclave to which a stirrer is applied. Sodium laurylbenzenesulfonate and 0.5 parts by mass of calcium triphosphate, 200 parts by mass of pure water, polymerized at a temperature of 95 ° C for 6 hours, and further polymerized at a temperature of 130 ° C 2 hours. After completion of the reaction, washing, dehydration, and drying were carried out to obtain crosslinked particles (E-1). The crosslinked particles had an average particle diameter of 8 μm and a refractive index of 1.494.

A crosslinked particle (E-2) having an average particle diameter of 1 μm and a refractive index of 1.494 was obtained by the same method as E-1 except that 1.5 parts by mass of the third calcium phosphate was used.

Further, a crosslinked particle (E-3) having an average particle diameter of 3 μm and a refractive index of 1.494 was obtained in the same manner as in the production of E-1 except that 1.0 part by mass of the third calcium phosphate was used.

Further, 0.2 parts by mass of the third calcium phosphate was used, and after the same method as in the production of E-1, the crosslinked particles (E-4) having an average particle diameter of 13 μm and a refractive index of 1.494 were obtained.

[Colorant (F)]

As a coloring agent, a fluorescent whitening agent 2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole) (Ubtex OB manufactured by Chiba Specialty Chemicals Co., Ltd.) (F-1), An anthraquinone derivative of a resin coloring agent (Dialezin BLUE J, manufactured by Mitsubishi Chemical Corporation) (F-2).

[surfactant (G)]

As the amine-based surfactant, N-hydroxyethyl-N-(2-hydroxyalkyl)amine (Dasper 125B manufactured by Sanhao Oil Co., Ltd.) is used as (G-1). As an anionic surfactant, sodium lauryl sulfonate (G-2) is used as a non-amine nonionic surfactant to use glyceryl stearate (G-3). .

According to Table 1-2~1-3, the styrene copolymer of (A-1)~(A-4), crosslinked particles B-2, C, D, (E-1)~( Unmelted compound of E-4), hindered amine compound of bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, 2-(2H-benzotriazole-2 a benzotriazole-based compound of -4,6-di-t-pentanol, a coloring agent of (F-1), (F-2), N-hydroxyethyl-N-(2-hydroxyalkane) After mixing the amine-based surfactant of the amine (G-1), the mixture was kneaded by a uniaxial extruder having a diameter of 40 mm, a temperature of 240 ° C, and a number of spiral rotations of 100 rpm. After granulation, Table 1-2 was obtained. The particles of the styrene resin composition 1-1 to 1-23 shown in 1-3.

[Examples 1-1 to 1-10, Comparative Examples 1-1 to 1-15]

Using a styrene-based resin composition 1-1 to 1-23, a 2-pound in-line spiral injection molding machine (manufactured by Niigata Iron Works Co., Ltd.) was used for injection molding at a cylinder temperature of 230 ° C to obtain a size of 300 mm × 300 mm × 0.5 mm thick, 300 mm × 300 mm × 2 mm thick, 300 × 300 × 10 mm thick molded body.

The optical properties, light resistance, dimensional stability (water absorption warpage), antistatic property (surface specific resistance value), and thermal stability of the obtained molded body were evaluated and shown in Tables 1-4 to 1-6.

Further, the styrene-based copolymer of (A-1) to (A-4) crosslinks the unmelted compound of the particles (B-1) to (B-3), C and D, and double (2, 2, 6,6-tetramethyl-4-piperidinyl) sebacate, benzotriazole of 2-(2H-benzotriazol-2-yl)-4,6-di-t-pentanol The compound, the coloring agent of (F-1) and (F-2), and the surfactant of (G-1)~(G-3) are mixed according to the mixing ratio shown in Table 2-2~2-3, to 40mm. The uniaxial extruder of the diameter was kneaded at a temperature of 240 ° C and a number of spiral rotations of 100 rpm, and pelletized to obtain pellets of styrene resin compositions 2-1 to 2-3 shown in Table 2-2.

[Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-15]

The styrene-based resin composition 2-1 to 2-23 was used in an in-line spiral injection molding machine (manufactured by Niigata Iron Works Co., Ltd.), and after the injection molding at a cylinder temperature of 230 ° C, a size of 300 mm × 300 mm × 0.5 mm was obtained. A molded body having a thickness of 300 mm × 300 mm × 2 mm and a thickness of 300 × 300 × 10 mm.

The optical properties, light resistance, dimensional stability (water absorption warpage), antistatic property (surface specific resistance value), and thermal stability of the molded body were evaluated, and are shown in Tables 2-3 to 2-5.

It can be judged that the haze is 99% or more, the total light transmittance is 65% or more, the diffusivity is 17% or more, the b value is 1.0 or less, and the luminance is 3500 cm/m ² or more. Moreover, in order to exhibit good light resistance, the color difference ΔE must be less than 1, so that the water absorption warpage must be 1 mm or less for good dimensional stability, and the heating deformation must be less than 1 mm for good thermal stability. In order to exhibit good antistatic properties, the surface specific resistance must be 10 ¹² Ω or less.

[Examples 1-11, 2-11]

A sheet was produced by a T-die extruder using styrene resin compositions 1-1 and 2-1. In addition, the extruder is 65mm Full-scraper spiral single-axis extruder. The temperature of each of the flaking cylinders was operated and formed at 230 °C. The optical characteristics, light resistance, water absorption warpage, thermal stability, and surface specific resistance of the obtained extruded sheet are shown in Tables 1-4 and Table 2-3.

Each measurement method of the obtained light-diffusion sheet is as follows.

(1) Total light transmittance and haze: The measurement was carried out using a HAZE meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd. based on ASTM D-1003.

(2) the diffusion rate: using Nippon Denshoku Industries Co., Ltd. goniophotometer (GC5000L), measured light-receiving angle of 0 ° light transmittance I _0, the light beam angle of 70 ° transmittance I _70, by the following equation.

Diffusion rate (%) = (I ₇₀ /I ₀ ) × 100

(3) Light resistance: The aging tester manufactured by Toyo Seiki Co., Ltd., Atras CI65A was used, and the color difference ΔE after irradiation for 400 hours was measured.

(4) Dimensional stability (absorption warping): The light-diffusing sheet cut into a size of 180 mm × 180 mm was placed in an atmosphere of 50 ° C and a humidity of 80% for 7 days, and the amount of deformation of the four corners before and after the placement was measured by a cursor. The average value is made into the value of water absorption warping, and this value is used as a measure of dimensional stability.

(5) Yellowness and chromatic aberration: L, a, and b were measured by a color difference meter (Σ-80) manufactured by Nippon Denshoku Co., Ltd., and the b value represents a yellowness scale. Further, the color difference ΔE of the light resistance evaluation was obtained by the following formula.

△E=((L-L') ² +(a-a') ² (b-b') ² ) ^1/2

Here, L, a, and b are the hue before the light resistance evaluation, and L', a', and b' are the hue after the light resistance evaluation (after 400 hours of irradiation).

(6) Heat deformation: The light diffusion sheet cut into 300 mm × 300 mm size is placed in an atmosphere of 80 ° C for 7 days, and the deformation amount of the four corners after the placement is measured by a cursor, and the average value is taken as the value of the heating deformation. The value is a measure of thermal stability.

(7) Antistatic property: The surface resistivity of the molded body was measured by a surface natural resistance measuring machine (R503) manufactured by KAWAGUCHI Co., Ltd. at a temperature of 23 ° C and a humidity of 50% RH based on JIS K-6911. Value, this value is used as a measure of antistatic properties.

(8) Brightness: 9 cold cathode tubes with a diameter of 5 mm and a length of 200 mm were placed on the reflective sheet, and a light diffusion sheet cut into a size of 180 mm × 180 mm was placed at 5 mm on the cold cathode tube, and placed thereon. Diffusion film, prism sheet, and brightness enhancement film. The cold cathode tube was turned on in a dark room, and a total of 36 points were measured at a distance of 30 mm from a position of 1000 mm of the light-diffusing sheet using a topcon company brightness meter (BM-7), and an average value was obtained.

The evaluation other than the light diffusion sheet was carried out as follows.

(9) Refractive index: The unmelted compound was measured in an atmosphere of a wavelength of 589 nm and 23 ° C in an Abbe refractometer. Further, the styrene-based copolymer was measured at a temperature of 25 ° C using a digital refractometer (RX-2000, manufactured by ATAGO Co., Ltd.) using a saturated aqueous solution of potassium iodide in a contact liquid.

(10) Determination of the unit content of methacrylic acid monomer in the styrene copolymer: I. Determination of the total amount of methacrylic monomer units and residual methacrylic acid in the styrene copolymer 1) in 2 g of styrene To the copolymer, 100 ml of a chloroform:ethanol mixed solution (2:1) was added to dissolve. 2) Add 0.5% phenolphthalein here. The indicator of the ethanol solution was titrated with a 0.1 N potassium hydroxide solution. The indicator color is the end point when it disappears in 30 seconds. 3) As a blank test, chloroform: ethanol mixed solution (2:1) and 100 ml of 2) were carried out in the same manner. 4) The methacrylic acid content in the styrene-based copolymer was determined by the following formula.

Methyl propylene content (%) = [{(A-B) × M} / (S × 1000)] × 100 A: 1) required titration (ml) B: 3) required titration ( M) S: mass of styrene copolymer (g) M: mass of methacrylic acid (8.6 (mg)) equivalent to 0.1 ml of 0.1 N potassium hydroxide and ethanol solution

II. Measurement of the amount of residual methacrylic acid in the styrene-based copolymer 0.5 g of the styrene-based copolymer was dissolved in 10 ml of chloroform, and N,N-dimethylformamide was used as an internal standard to determine the following The GC measurement conditions were measured.

Device name: GC14B FID detector cylinder made by Shimadzu Corporation: glass cylinder 3mm × 3m filler: diethylene glycol succinate carrier: nitrogen temperature: cylinder 110 ° C, injection port 180 ° C

III. The total amount of methacrylic monomer units and residual methacrylic acid in the styrene-based copolymer measured by I minus the amount of residual methacrylic acid in the styrene-based copolymer measured by II. It is the unit content of the methacrylic monomer in the styrene copolymer. When the measured value of the residual methacrylic acid in the styrene-based copolymer is less than 0.1% by mass, the amount of residual methacrylic acid is 0% by mass, and the methacrylic monomer unit in the styrene-based copolymer is obtained. content.

(11) Resin composition of a styrene-based copolymer: A styrene-based copolymer was dissolved in heavy chloroform, and a 2% solution was prepared to prepare a measurement sample, which was measured by FT-NMR (Model FX-90Q, manufactured by JEOL Ltd.). ¹³ C-NMR, calculated from the peak area of styrene and methyl methacrylate.

[Industrial Applicability]

The multi-layer sheet of the invention has good dimensional stability, light resistance, light diffusibility, antistatic property and brightness, and is particularly suitable for a screen lens such as a light-transmissive screen which projects a picture such as a television.

In addition, the contents of the patent application, the scope of the patent application, and the summary of the Japanese Patent Application No. 2006-209, filed on Jan. 19, 2006, and the Japanese Patent Application No. 2006-209984, filed on Jan. 1, 2006, are incorporated by reference. Make a disclosure of the cost of the invention, and extract it.

Claims (12)

A styrene resin composition characterized by being styrene based on 100 parts by mass of 91 to 97% by mass of a styrene monomer unit and 9 to 3% by mass of a (meth)acrylic monomer unit. The copolymer contains 2 to 10 parts by mass of a crosslinked copolymer having a refractive index difference of 0.05 to 0.15 to the styrene copolymer and an average particle diameter of 2 to 10 μm, and contains (meth)acrylic acid. The ester monomer is a crosslinked copolymer of a monomer unit, or a crosslinked copolymer containing methyl methacrylate and n-butyl acrylate as a monomer unit, or an average particle diameter of 0.5 to 2.5 parts by mass. 10 μm of polyorganosiloxane crosslinked particles and 0.1 to 2 parts by mass of a hindered amine compound, 0.1 to 2 parts by mass of a benzotriazole compound, and 0.0005 to 0.5 part by mass of a benzoxazole compound. The styrenic resin composition according to claim 1, wherein the hindered amine compound is bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate. A styrenic resin composition as claimed in claim 1, wherein the benzotriazole compound is 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetra Methyl butyl) phenol. The styrene resin composition according to any one of claims 1 to 3, wherein the benzoxazole compound is 2,5-thiophenediyl (5-t-butyl-1,3-) Benzooxazole). The styrene resin composition according to any one of the items 1 to 3, wherein the styrene resin composition further contains 0.1 to 3 parts by mass of the amine per 100 parts by mass of the styrene copolymer. Department interface A surfactant, or an anionic surfactant, and a non-amine nonionic surfactant. A styrenic resin composition according to claim 5, wherein the amine-based surfactant is N-hydroxyethyl-N-(2-hydroxyalkyl)amine. The styrene resin composition according to claim 5, wherein the mixing ratio of the anionic surfactant and the non-amine nonionic surfactant is an anionic surfactant/non-amine nonionic surfactant=0.5 /99.5~15/85 (mass ratio). The styrene resin composition according to claim 5, wherein the anionic surfactant is an organic sulfonic acid metal salt having 10 to 14 carbon atoms, and the non-amine nonionic surfactant is a glycerin fatty acid ester. A molded article obtained by the styrene resin composition according to any one of claims 1 to 8, which has a thickness of 1 to 7 mm. The molded article of claim 9, wherein the molded body is an injection molded body. The molded article of claim 9, wherein the formed body is an extruded body. A light-diffusing sheet characterized by using the formed body according to any one of the items 9 to 11.