TW201938673A - Styrene-based resin composition for optical applications, and optical component - Google Patents

Abstract

Provided are: a styrene-based resin composition having excellent initial uniform surface light-emission properties and excellent long-term uniform surface light-emission properties; and an optical component. A styrene-based resin composition for optical applications, which contains (a) a styrene-based resin, (b) a phosphorus-containing antioxidant agent and/or a phenol-type antioxidant agent and (c) an anthraquinone-type compound, the styrene-based resin composition being characterized in that the content of the component (b) is 0.02 to 1% by mass relative to 100% by mass of the styrene-based resin composition and the content of the component (c) is 0.1 to 90 ppb relative to the total mass of the resin components.

Description

   Optical styrene resin composition and optical component   

The present invention relates to an optical styrene resin composition and an optical component.

Styrene resins are excellent in transparency, rigidity, low water absorption, and dimensional stability, and have excellent moldability. Therefore, they are widely used in electrical products by various molding methods such as injection molding, extrusion molding, and blow molding. Various industrial materials, food packaging containers, and miscellaneous goods. In addition, it is also applied to optical members such as light guide plates for applications that exhibit transparency.

The backlight device of a liquid crystal display includes a direct type backlight device in which a light source is arranged on the front surface of the display device, and a side light type backlight device in which a light source is arranged on the side surface. The light guide plate is assembled in a side-light type backlight device, and plays a role of guiding light from the side to a liquid crystal panel, and is used in a wide range of applications such as televisions, desktop personal computer displays, notebook personal computers, mobile phones, and car navigation. As a styrene-based resin composition used for such a light guide plate, Patent Document 1 describes a styrene-based resin composition that has a small change in transmittance over a long period of time.

[Existing technical literature]

[Patent Literature]

[Patent Document 1] International Publication No. 2013/094642

However, in the prior art described in the above-mentioned literature, although the change in transmittance caused by long-term use can be suppressed, there are problems in that uniform surface light emission and long-term uniform surface light emission are insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to achieve a problem of providing a styrene-based resin composition and an optical component that are excellent in initial uniform surface light emission and excellent in long-term uniform surface light emission.

According to the present invention, there is provided a styrene-based resin composition for optics, which contains (a) a styrene-based resin, (b) a phosphorus-based antioxidant and / or a phenol-based antioxidant, and (c) an anthraquinone-based compound, benzene The content of the (b) in 100% by mass of the ethylene-based resin composition is 0.02 to 1% by mass, and the content of the (c) with respect to the total mass of the resin component is 0.1 to 90 ppb.

The present inventors have conducted intensive studies in order to achieve the above-mentioned problems, and as a result, found that the above-mentioned object can be achieved by using a specific amount of a phosphorus-based antioxidant and / or a phenol-based antioxidant and an anthraquinone-based compound, thereby completing the present invention.

The following illustrates various embodiments of the present invention. Various embodiments shown below can be combined with each other.

It is preferable that the average transmittance at a wavelength of 380nm to 780nm at an optical path length of 115mm is 80% or more (wherein the above average transmittance is measured using the following test pieces: injection molding at a barrel temperature of 230 ° C and a mold temperature of 50 ° C) To obtain a plate-shaped molded product with a thickness of 127 × 127 × 3 mm, and a test piece with a thickness of 115 × 85 × 3 mm was cut out from the molded product, and the end surface was polished and polished to make a test piece with a mirror surface on the end surface).

The ratio of the transmittance (t480) at a wavelength of 480 nm to the transmittance (t580) at a wavelength of 580 nm is preferably as follows.

0.96 <t580 / t480 <1.04

Preferably, (a) a styrene-based resin, (b) a phosphorus-based antioxidant and / or a phenol-based antioxidant, and (c) an anthraquinone-based compound, and 100% by mass of the styrene-based resin composition. The content is 0.02 to 1% by mass, and the average transmittance at a wavelength of 380nm to 780nm at a light path length of 115mm is 80% or more (where the above average transmittance is measured using the following test pieces: at a barrel temperature of 230 ° C and a mold temperature of 50 The injection molding was performed under the condition of ℃ to obtain a plate-shaped molded product with a thickness of 127 × 127 × 3 mm. A 115 × 85 × 3 mm-thick test piece was cut out from the molded product, and the end surface was polished and polished to make a mirror-shaped end surface. Test piece), the ratio of the transmittance (t480) at a wavelength of 480nm to the transmittance (t580) at a wavelength of 580nm has the following relationship.

0.96 <t580 / t480 <1.04

An optical component including the optical styrene-based resin composition.

The heat-resistant styrene-based resin composition of the present invention can obtain a styrene-based resin composition and an optical component that are excellent in initial uniform surface light emission and excellent in long-term uniform surface light emission.

The present invention is explained in detail below.

<< styrene resin >>

The styrene-based resin of the present invention can be obtained by polymerizing a styrene-based monomer. Styrene-based monomers are styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, ethylstyrene, and p-tertiary as aromatic vinyl-based monomers. One type or a mixture of two or more types, such as butylstyrene, is preferably styrene. In addition, a styrene-based monomer and a copolymerizable monomer may be copolymerized within a range not impairing the characteristics of the present invention. Examples thereof include (meth) acrylic acids such as acrylic acid and methacrylic acid, acrylonitrile, and methacrylic acid Vinyl cyanide monomers such as nitrile; α, β-ethylenically unsaturated carboxylic acids such as maleic anhydride and fumaric acid; fluorene imines such as phenylmaleimide and cyclohexylmaleimide Body class. Among them, a polymer composed of only a styrene-based monomer is preferable, and a styrene homopolymer is particularly preferable.

The styrene-based resin composition is preferably composed of a styrene-based resin and various additives. The proportion of the styrene-based resin in 100% by mass of the styrene-based resin composition is, for example, 90 to 99.96% by mass, and preferably 95 to 99.96% by mass. The specific ratio of the styrene resin is, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.96% by mass, or may be a value within a range between any two values exemplified here. .

When the styrene-based resin is a styrene- (meth) acrylic copolymer resin obtained by copolymerizing a styrene-based monomer and (meth) acrylic acid, the content of the styrene-based monomer unit in the styrene-based resin is preferably 80.0 ~ 99.9% by mass, and the content of the (meth) acrylic unit is 0.1 to 20.0% by mass. The total content of the styrene-based monomer unit and the (meth) acrylic unit is 100% by mass. (Meth) acrylic acid means acrylic acid, methacrylic acid, and the like, and methacrylic acid is preferred.

The measurement of the (meth) acrylic unit content in a styrene resin is implemented at room temperature. Weigh 0.5g of styrene resin and dissolve it in a mixed solution of toluene / ethanol = 8/2 (volume ratio), then perform neutralization titration with a 0.1mol / L ethanol solution of potassium hydroxide, and check the end point. The amount of the solution was used to calculate the mass-based content of the (meth) acrylic unit. In addition, an automatic potentiometric titrator can be used, and measurement can be performed using AT-510 manufactured by Kyoto Electronics Industry Co., Ltd. The content of the (meth) acrylic unit in the styrene-based resin can be adjusted by the composition ratio of the styrene-based monomer and the (meth) acrylic monomer as raw materials during the polymerization of the styrene-based resin. The range is adjusted by mixing a styrene resin containing a (meth) acrylic unit and a styrene resin containing no (meth) acrylic unit.

Examples of the polymerization method of the styrene resin include known styrene polymerization methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. From the aspects of quality and productivity, bulk polymerization and solution weighting are preferred, and continuous polymerization is preferred. Examples of the solvent include alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene; ketones such as acetone and methyl ethyl ketone; and aliphatic hydrocarbons such as hexane and cyclohexane.

When the styrene resin is polymerized, a polymerization initiator or a chain transfer agent can be used as necessary. The polymerization initiator is preferably a radical polymerization initiator, and examples of known and commonly used polymerization initiators include 1,1-bis (t-butylperoxy) cyclohexane and 2,2-bis (t-butylperoxy). Peroxidation ketals such as butane, 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, 1,1-bis (tert-amylperoxy) cyclohexane; peroxides Hydrogen peroxides such as cumene hydroperoxide and tert-butyl hydroperoxide; alkyl peroxides such as tert-butyl peroxyacetate and tert-butyl perisonononanoate; tert-butyl cumene peroxide, Di-tert-butyl peroxide, dicumyl peroxide, di-tert-butyl peroxide and other dialkyl peroxides; tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxide Peroxy esters such as isopropyl monocarbonate; peroxy esters such as t-butylperoxy isopropyl carbonate; peroxy carbonates such as polyether tetrakis (t-butylperoxycarbonate); N, N'-azo Bis (cyclohexane-1-nitrile), N, N'-azobis (2-methylbutyronitrile), N, N'-azobis (2,4-dimethylvaleronitrile), N, N'-azobis [2- (hydroxymethyl) propionitrile], etc., one of these can be used or 2 Or more thereof. Examples of the chain transfer agent include aliphatic thiols, aromatic thiols, pentaphenylethane, α-methylstyrene dimer, and terpinene.

In continuous polymerization, a well-known complete mixing tank-type stirred tank, a tower reactor, and the like are used in the first polymerization step, and the polymerization reaction is controlled by adjusting the polymerization temperature to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate. The polymerization solution containing the polymer obtained in the polymerization step is transferred to a devolatilization step to remove unreacted monomers and a polymerization solvent. The devolatilization step includes a vacuum devolatilization tank with a heater, a devolatilization extruder with a vent, and the like. The polymer in a molten state obtained in the devolatilization step is transferred to a granulation step. In the granulation step, the molten resin is extruded linearly from the porous die, and processed into a pellet shape by a cold cutting method, an aerial hot cutting method, or an underwater hot cutting method.

<< Phosphorus-based antioxidant / phenol-based antioxidant >>

The styrene-based resin composition of the present invention contains at least one of a phosphorus-based antioxidant and a phenol-based antioxidant as an essential component. It is preferable to contain both a phosphorus-type antioxidant and a phenol-type antioxidant.

The phosphorus-based antioxidant preferably contains 0.02 to 1% by mass, more preferably 0.02 to 0.50% by mass, and even more preferably 0.02 to 0.30% by mass in 100% by mass of the styrene-based resin composition. The phenol-based antioxidant preferably contains 0.02 to 1% by mass, more preferably 0.02 to 0.50% by mass, and even more preferably 0.02 to 0.30% by mass in 100% by mass of the styrene-based resin composition. When a phosphorus-based or phenol-based antioxidant is added at the above content, long-term uniform surface luminescence is excellent. The specific content of the phosphorus-based antioxidant and the phenol-based antioxidant in 100% by mass of the styrene-based resin composition is, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08, respectively. , 0.09, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1% by mass, can also be any exemplified here Value between two values.

Phosphorus antioxidants are phosphites which are trivalent phosphorus compounds. Examples of the phosphorus-based antioxidant include tris (2,4-di-tert-butylphenyl) phosphite and 2,2'-methylenebis (4,6-di-tert-butyl-1-phenoxy). (2-ethylhexyloxy) phosphorus, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, 4,4'-diphenylene secondary phosphonic acid tetra (2,4-di-tert Butylphenyl) ester, 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxo-3,9-diphosphine [5.5] Undecane, cyclic neopentane tetrayl bis (2,4-di-tert-butylphenyl phosphite), distearyl pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol di Phosphite, bis [2-methyl-4,6-bis (1,1-dimethylethyl) phenyl] ethyl phosphite, 9,10-dihydro-9-oxy-10-phosphorus Heterophenanthrene-10-oxide, tetra (2,4-di-tert-butyl-5-methylphenyl) -4,4'-diphenylene diphosphinate and the like. As the phosphorus-based antioxidant, an antioxidant excellent in hydrolysis resistance is preferred, and tris (2,4-di-tert-butylphenyl) phosphite and 2,2'-methylenebis (4,6-di-tert-tertiary) are preferred. Butyl-1-phenoxy) (2-ethylhexyloxy) phosphorus, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, 3,9-bis (2,6-di-tert-yl Butyl-4-methylphenoxy) -2,4,8,10-tetraoxy-3,9-diphosphospiro [5.5] undecane. Tris (2,4-di-t-butylphenyl) phosphite is particularly preferred. The phosphorus-based antioxidant may be used alone or in combination of two or more kinds.

A phenolic antioxidant is an antioxidant which has a phenolic hydroxyl group in a basic skeleton. Examples of the phenolic antioxidant include stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 3,9-bis [2- [3- (3-tert- Butyl-4-hydroxy-5-methylphenyl) propanyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxocyclo [5.5] undecane, Ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], 4,6-bis (octylthiomethyl) -o-methyl Phenol, 4,6-bis [(dodecylthio) methyl] -o-cresol, 2,4-dimethyl-6- (1-methylpentadecyl) phenol, pentaerythritol tetra [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], DL-α-tocopherol, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5- (Methylbenzyl) -4-methylphenylacrylate, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl Acrylate, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) Butane, 4,4'-butylenebis (3-methyl-6-tert-butylphenol), bis [3,3-bis (4'-hydroxy-3'-tert-butylphenyl) -butyric acid ] -Glycol esters and the like. Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy- 5-methylphenyl) propanyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxocyclo [5.5] undecane, ethylenebis (oxyethylene) Ethyl) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ester]. The phenolic antioxidant may be used alone or in combination of two or more.

As described above, there are many phosphorus-based antioxidants and phenol-based antioxidants. Among them, it is particularly preferred that the phosphorus-based antioxidant is at least one selected from the following (B1-1) to (B1-4). The oxidizing agent is at least one selected from (B2-1) to (B2-4) shown below.

(B1-1) Tris (2,4-di-tert-butylphenyl) phosphite

(B1-2) 2,2'-Methylenebis (4,6-di-tert-butyl-1-phenoxy) (2-ethylhexyloxy) phosphorus

(B1-3) bis (2,4-dicumylphenyl) pentaerythritol diphosphite

(B1-4) 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxo-3,9-diphosphinospiro [5.5 Undecane

(B2-1) Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate

(B2-2) 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propanyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxocyclo [5.5] undecane

(B2-3) ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate]

(B2-4) Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]

Examples of the method for adding the phosphorus-based antioxidant and the phenol-based antioxidant include a method of adding and mixing in a polymerization step, a devolatilization step, and a granulation step of a styrene resin; an extruder and an injection molding during the molding process are used. A method of adding and mixing by a machine or the like; after adjusting the hydrophilic additive of the resin composition to a high concentration, diluting and mixing to a target content with a non-added styrene resin is not particularly limited.

<< Anthraquinones >>

The styrene-based resin composition of the present invention contains an anthraquinone-based compound as an essential component. The content of the anthraquinone-based compound in the styrene-based resin composition with respect to the total mass of the resin component is preferably 0.1 to 90 ppb, more preferably 1 to 70 ppb, still more preferably 5 to 50 ppb, and particularly preferably 15 to 45 ppb. When an anthraquinone-based compound is added at the above content, both initial and long-term uniform surface luminescence are excellent. The specific content of the anthraquinone-based compound is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 ppb, or any value between any two of the values exemplified here.

Examples of the anthraquinone-based compound include the following. In addition, the name given below is COLOR INDEX GENERIC NAME. Disperse Blue14, Disperse Blue60, Disperse Blue197, Disperse Blue198, Disperse Blue334, Disperse Blue72, Solvent Blue11, Solvent Blue35, Solvent Blue36, Solvent Blue45, Solvent Blue59, Solvent Blue63, Solvent Blue67, Solvent Blue78, Solvent Blue83, Solvent Blue87, Solvent Blue94, Solvent Blue95, Solvent Blue97, Solvent Blue104, Solvent Blue105, Solvent Blue122, Solvent Violet13, Solvent Violet33, Solvent Violet34, Solvent Violet14, Solvent Violet31, Solvent Violet36, SolventViolet37, Disperse Violet26, Disperse Violet28, Disperse Violet31 Solvent Green20, Solvent Green28.

<< Other additives >>

The styrene-based resin composition may contain mineral oil within a range that does not impair the colorless transparency of the present invention. In addition, it may contain internal lubricants such as stearic acid and ethylenebisstearylamine; sulfur-based antioxidants, lactone-based antioxidants, ultraviolet absorbers, hindered amine-based stabilizers, antistatic agents, external lubricants, etc. additive. In addition, as the external lubricant, ethylenebisstearylamine is preferable, and the content is preferably 30 to 200 ppm in the resin composition.

The ultraviolet absorber has a function of suppressing deterioration and coloration due to ultraviolet rays, and examples thereof include benzophenone-based, benzotriazole-based, triazine-based, benzoate-based, salicylate-based, and cyanoacrylate UV absorbers, such as based, aniline oxalate, malonate, and formazan. These can be used alone or in combination of two or more kinds, and a light stabilizer such as a hindered amine can also be used in combination.

The styrene-based resin composition of the present invention can be molded by a molding method corresponding to a target such as injection molding, extrusion molding, compression molding, blow molding, and the like, and its properties are not limited. For example, if it is a plate-shaped molded article, it can be processed into a light-guide plate, etc. The obtained molded article is used as an optical member such as a light guide plate that functions by projecting light into the molded article. For optical members such as a light guide plate, since the projection distance (light path length) of light is long, a material having excellent uniform surface luminescence is preferred. Here, the term “excellent uniform surface light emission property” refers to a material that is excellent in transmittance and has a small wavelength dependence of light absorption.

As for the transmittance, the average transmittance at a wavelength of 380 nm to 780 nm at an optical path length of 115 mm is preferably 80% or more, more preferably 82.5% or more, and still more preferably 84% or more. The average transmittance was measured using the following test pieces: injection molding was performed under the conditions of a barrel temperature of 230 ° C and a mold temperature of 50 ° C to obtain a plate-shaped molded product having a thickness of 127 × 127 × 3 mm, and cut from the molded product. A test piece with a thickness of 115 × 85 × 3 mm was obtained, and its end surface was polished and ground to make a test piece with a mirror surface on the end surface. The absolute value of the difference from the initial average transmittance after storage at 80 ° C. for 1,000 hours is preferably 2.0% or less, more preferably 1.5% or less, and even more preferably 1.2% or less.

The wavelength dependence of the light absorbance can be evaluated, for example, by the ratio (t580 / t480) of the transmittance (t480) at a wavelength of 480 nm to the transmittance (t580) at a wavelength of 580 nm. In the present invention, the ratio (t580 / t480) is preferably 0.96 <t580 / t480 <1.04, more preferably 0.97 <t580 / t480 <1.03, and still more preferably 0.98 <t580 / t480 <1.02. Here, the wavelength dependence of the light absorption means that the above ratio (t580 / t480) is close to 1 in principle. The above ratio (t580 / t480) is specifically, for example, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, or a value between any two values exemplified here.

The transmittance measurement at an optical path length of 115 mm was performed in the following procedure. Using pellets of a styrene-based resin composition, injection molding was performed at a cylinder temperature of 230 ° C and a mold temperature of 50 ° C to form a plate-shaped molded article having a thickness of 127 × 127 × 3 mm. The samples used for evaluating the long-term thermal stability and qualitative properties were stored in an oven at 80 ° C. for 1000 hours. Next, a 115 × 85 × 3 mm thick test piece was cut out of the plate-shaped molded product, and the end surface was polished and ground to produce a plate-shaped molded product having a mirror surface on the end surface. For the plate-shaped molded product after grinding, the wavelength at a light path length of 115 mm was measured using an ultraviolet-visible spectrophotometer V-670 manufactured by JASCO Corporation under the condition of incident light having a size of 20 × 1.6 mm and a divergence angle of 0 °. 350nm ~ 800nm spectral transmittance.

The light guide plate is a member having a function of incident light from an end surface (side surface) of a plate-shaped molded product, and guiding light to a front surface (light-emitting surface) of the molded product by a reflection pattern formed on the rear surface (non-light-emitting surface) of the molded product. Perform surface light emission. The reflection pattern can be formed by a screen printing method, an injection molding method, a laser method, or an inkjet method. When processing from a plate-shaped molded product into a light guide plate, it is preferable to polish the entire light incident surface or end surface to form a mirror surface. In order to improve the uniformity of the emitted light, a prism pattern or the like may be provided on the front surface (light emitting surface) of the plate-shaped molded product. The pattern on the front or the back of the plate-shaped molded product can be formed during the molding of the plate-shaped molded product. For example, a pattern is formed using a mold shape during injection molding, and a pattern is formed by roll transfer during extrusion molding.

[Example]

The following examples illustrate the present invention in detail, but the present invention is not limited to these examples.

(Manufacture of styrene resin)

The first reactor, the second reactor as a complete mixing type stirred tank, and the third reactor as a plug flow reactor with a static mixer were connected in series to constitute a polymerization step, and styrene was carried out under the conditions shown in Table 1. Manufacture of resin. The capacity of each reactor was set to 39 liters in the first reactor, 39 liters in the second reactor, and 16 liters in the third reactor. A raw material solution was prepared according to the raw material composition described in Table 1, and the raw material solution was continuously supplied to the first reactor at the flow rate described in Table 1. The polymerization initiator was added to the raw material solution so that the addition concentration (concentration based on the mass basis of the total amount of raw materials styrene and methacrylic acid) described in Table 1 at the inlet of the first reactor was uniformly mixed. The polymerization initiators described in Table 1 are as follows.

Polymerization initiator: 2,2-bis (4,4-tert-butylcyclohexyl peroxide) propane (Pertetra A manufactured by Nippon Oil Co., Ltd. was used.)

It should be noted that a temperature gradient was provided in the third reactor along the flow direction, and the middle portion and the outlet portion were adjusted to the temperatures in Table 1.

Next, the polymer-containing solution continuously taken from the third reactor was introduced into a vacuum devolatilization tank with a preheater composed of two stages in series. The temperature of the preheater was adjusted according to the resin temperature described in Table 1, and adjusted. The unreacted styrene was separated from ethylbenzene at the pressures shown in Table 1, and then linearly extruded from the porous die, and the strand was cooled by a cold cutting method and cut into pellets.

(Examples 1 to 4, Comparative Examples 1 to 3)

Using a single-screw extruder with a screw diameter of 40 mm, a barrel temperature of 230 ° C. and a screw revolution of 100 rpm were applied to (a) a styrene-based resin PS-1 and (b) a phosphorus-based antioxidant / The phenol-based antioxidant and (c) anthraquinone-based compound are melt-kneaded to obtain pellets. The (b) phosphorus-based antioxidant and phenol-based antioxidant used in Table 2 are 2,2'-methylenebis (4,6-di-tert-butyl-1-phenoxy) (2-ethylhexyl), respectively. (Oxy) phosphorus (ADKSTAB HP-10 by ADEKA), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox by BASF Japan) 1076); (c) The anthraquinone-based compound is Solvent Violet33 (Blue J manufactured by Mitsubishi Chemical Corporation).

In addition, using the obtained pellets, injection molding was performed at a cylinder temperature of 230 ° C. and a mold temperature of 50 ° C. to form a plate-shaped molded product having a thickness of 127 × 127 × 3 mm. In order to evaluate the long-term thermal stability, the obtained molded article was kept in an oven at 80 ° C. for 1000 hours. In order to evaluate the optical characteristics of the initial molded product before storage and the molded product after storage, a 115 × 85 × 3 mm thick test piece was cut from the plate-shaped molded product, and the end surface was polished and polished to produce a plate-shaped molding with a mirror surface on the end surface. Product. The polished plate-shaped molded article was measured with a wavelength of 350 nm to 800 nm at an optical path length of 115 mm under an incident light having a size of 20 × 1.6 mm and a divergence angle of 0 ° using an ultraviolet-visible spectrophotometer V-670 manufactured by JASCO Corporation. Spectral transmission.

【Table 2】

Table 2 shows the evaluations based on the following criteria. In addition, X, △, ○, and ◎ were set, and X was the worst and ◎ was the most excellent. The evaluation was sequentially increased in the order of X, △, ○, and ◎.

Permeability

：: The transmittance is 84% or more.

○: The transmittance is 82.5% or more and less than 84%.

Δ: The transmittance is 80% or more and less than 82.5%.

×: The transmittance is less than 80%.

Wavelength dependence

◎: 0.98 <t580 / t480 <1.02

○: 0.97 <t580 / t480 ≦ 0.98 or 1.02 ≦ t580 / t480 <1.03

△: 0.96 <t580 / t480 ≦ 0.97 or 1.03 ≦ t580 / t480 <1.04

×: t580 / t480 ≦ 0.96 or t580 / t480 ≧ 1.04

Uniform surface luminosity

This project is a combined evaluation of transmittance and wavelength dependence.

：: Both transmittance and wavelength dependence are ◎.

○: Both transmittance and wavelength dependence are ○ or more and at least one is ○.

Δ: Both transmittance and wavelength dependence are Δ or more and at least one is Δ.

×: At least one of transmittance and wavelength dependence is ×.

Long-term uniform surface luminosity

This project is a comprehensive evaluation of the initial uniform surface luminescence and surface uniform luminescence after a long-term thermal stability test (80 ° C, after 1000 hours).

：: The initial uniform surface luminescence is ◎ and the uniform surface luminescence after a long-term thermal stability test is ○ or more.

○: The initial uniform surface light emission is ○ and the uniform surface light emission after a long-term thermal stability test is Δ or more.

Δ: The initial uniform surface luminosity was Δ and the uniform surface luminescence after a long-term thermal stability test was Δ.

×: The initial uniform surface luminescence is ×, or the uniform surface luminescence after a long-term thermal stability test is ×.

The molded article of the example is excellent in initial uniform surface light emission and excellent in long-term uniform surface light emission.

[Industrial availability]

The optical styrene resin composition and molded article of the present invention are excellent in initial uniform surface luminescence and excellent in long-term uniform surface luminescence, and can be applied to, for example, a television, a desktop personal computer display, a notebook personal computer, a mobile phone, Widely used in car navigation.

Claims (5)

    A styrene-based resin composition for optics, comprising (a) a styrene-based resin, (b) a phosphorus-based antioxidant and / or a phenol-based antioxidant, and (c) an anthraquinone-based compound, said styrene-based resin The content of the (b) in 100 mass% of the resin composition is 0.02 to 1 mass%, and the content of the (c) to the total mass of the resin component is 0.1 to 90 ppb.         The optical styrene resin composition according to claim 1, wherein the average transmittance at a wavelength of 380 to 780 nm at a light path length of 115 mm is 80% or more, and the average transmittance is measured using the following test piece : Injection molding is performed under the conditions of a barrel temperature of 230 ° C and a mold temperature of 50 ° C to obtain a plate-shaped molded product having a thickness of 127 × 127 × 3 mm, and a test piece having a thickness of 115 × 85 × 3 mm is cut out from the plate-shaped molded product. , Polishing and grinding the end surface of the test piece to make a test piece with a mirror surface on the end face.         The optical styrene resin composition according to claim 1 or 2, wherein the ratio of the transmittance (t480) at a wavelength of 480nm to the transmittance (t580) at a wavelength of 580nm satisfies the following relationship: 0.96 <t580 / t480 <1.04 .         A styrene-based resin composition for optics, comprising (a) a styrene-based resin, (b) a phosphorus-based antioxidant and / or a phenol-based antioxidant, and (c) an anthraquinone-based compound, said styrene-based resin The content of (b) in 100% by mass of the resin composition is 0.02 to 1% by mass, and the average transmittance at a wavelength of 380nm to 780nm at an optical path length of 115mm is 80% or more. The average transmittance is as follows: Measurement of the test piece: injection molding was performed under the conditions of a barrel temperature of 230 ° C and a mold temperature of 50 ° C to obtain a plate-shaped molded product having a thickness of 127 × 127 × 3 mm, and 115 × 85 × 3 mm was cut out from the plate-shaped molded product. For a thick specimen, the end surface of the specimen is polished and polished to produce a specimen with a mirror surface on the end surface. The ratio of the transmittance (t480) at a wavelength of 480nm to the transmittance (t580) at a wavelength of 580nm satisfies the following relationship: 0.96 < t580 / t480 <1.04.         An optical component containing the styrene-based resin composition for optics according to any one of claims 1 to 4.