KR20200128551A - Optical styrenic resin composition and optical parts - Google Patents

Abstract

It provides a styrenic resin composition and optical component excellent in initial uniform surface luminescence and long-term uniform surface luminescence.
(a) a styrene resin, (b) a phosphorus antioxidant and/or a phenolic antioxidant, and (c) an anthraquinone compound,
The content of (b) in 100% by mass of the styrene resin composition is 0.02 to 1% by mass,
The content of (c) relative to the total mass of the resin component is 0.1 to 90 ppb, characterized in that the optical styrenic resin composition.

Description

Optical styrenic resin composition and optical parts

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

Styrene resins have excellent properties such as transparency, stiffness, low water absorption, and dimensional stability, and excellent molding processability. Electrical products, various industrial materials, food packaging containers, and miscellaneous goods are made by various molding methods such as injection molding, extrusion molding, and blow molding. It is widely used as such. In addition, it is used for optical members such as light guide plates for the purpose of utilizing transparency.

The backlight of a liquid crystal display includes a direct type backlight in which a light source is disposed in front of the display device and an edge light type backlight in which a light source is disposed in a side surface. The light guide plate is inserted into the edge light type backlight and serves to guide the light from the side to the liquid crystal panel, and is used for various purposes such as TV, desktop personal computer monitor, notebook type personal computer, mobile phone, car navigation, etc. do. As a styrene resin composition used for such a light guide plate, a styrene resin composition having a small change in transmittance even when used for a long period of time is described in Patent Document 1.

International Publication No. 2013/094642

However, in the prior art described in the above document, a change in transmittance in long-term use can be suppressed, but there is a problem in that the uniform surface luminescence property and the long-term uniform surface luminescence property are insufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a styrenic resin composition and optical component having excellent initial uniform surface luminescence and long-term uniform surface luminescence.

According to the present invention, (a) a styrene resin, (b) a phosphorus antioxidant and/or a phenolic antioxidant, and (c) an anthraquinone compound, and the above (b) in 100% by mass of the styrene resin composition The content of (c) is from 0.02 to 1% by mass, and the content of (c) with respect to the total mass of the resin component is from 0.1 to 90 ppb. A styrene resin composition for optics is provided.

The present inventors have conducted extensive research in order to achieve the above object, and found that the above object is achieved by using a specific amount of a phosphorus antioxidant and/or a phenolic antioxidant in combination with an anthraquinone compound, The present invention has been completed.

Hereinafter, various embodiments of the present invention will be illustrated. The following various embodiments can be combined with each other.

Preferably, the average transmittance at a wavelength of 380 nm to 780 nm at a length of 115 mm is 80% or more (however, the average transmittance is 127 × 127 × 3 mm thick obtained by injection molding at a cylinder temperature of 230°C and a mold temperature of 50°C. A test piece having a thickness of 115 × 85 × 3 mm is cut out from a plate-shaped molded article, and the cross section is polished by buffing, and the resulting cross section is measured using a test piece having a mirror surface).

Preferably, the ratio of the transmittance at a wavelength of 480 nm (t480) to the transmittance at a wavelength of 580 nm (t580) is in the following relationship.

0.96 <t580/t480 <1.04

Preferably (a) a styrene resin, (b) a phosphorus antioxidant and/or a phenolic antioxidant and (c) an anthraquinone compound, and the content of (b) in 100% by mass of the styrene resin composition Is 0.02 to 1 mass%, and the average transmittance at a wavelength of 380 nm to 780 nm at a length of 115 mm is 80% or more (however, the average transmittance is 127 × obtained by injection molding at a cylinder temperature of 230°C and a mold temperature of 50°C. A test piece with a thickness of 115 × 85 × 3 mm is cut out from a 127 × 3 mm thick plate-shaped molded product, and the cross section is polished by buffing, and measured using a test piece having a mirror surface on the prepared cross section), transmittance at a wavelength of 480 nm (t480) The ratio of the transmittance (t580) to the wavelength of 580 nm is the following relationship.

0.96 <t580/t480 <1.04

An optical component preferably made of the above optical styrene resin composition.

The heat-resistant styrenic resin composition of the present invention can obtain a styrenic resin composition and an optical component having excellent initial uniform surface luminescence and long-term uniform surface luminescence.

Hereinafter, the present invention will be described in detail.

<<Styrene resin>>

The styrenic resin of the present invention can be obtained by polymerizing a styrenic monomer. The styrene-based monomer is an aromatic vinyl-based monomer such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, ethylstyrene, pt-butylstyrene, and the like, or a mixture of two or more, preferably Is styrene. In addition, it may be copolymerized with a monomer copolymerizable with a styrene-based monomer within the range not impairing the characteristics of the present invention. For example, (meth)acrylic acids such as acrylic acid and methacrylic acid, acrylonitrile, and methacrylonitrile Vinyl cyanide monomers such as, and α,β-ethylenically unsaturated carboxylic acids such as maleic anhydride and fumaric acid, and imide-based monomers such as phenylmaleimide and cyclohexylmaleimide. In addition, among these, a polymer composed of only a styrene-based monomer is preferable, and a styrene homopolymer is particularly preferable.

The styrenic resin composition is preferably composed of a styrenic resin and various additives, and the ratio of the styrenic resin in 100% by mass of the styrenic resin composition is, for example, 90 to 99.96% by mass, preferably 95 to 99.96% by mass. Do. The proportion of the styrenic resin is specifically, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.96% by mass, and within the range between any two of the numerical values exemplified herein. You can open it.

When the styrene-based resin is a styrene-(meth)acrylic acid copolymer resin obtained by copolymerizing a styrene-based monomer and (meth)acrylic acid, the content of the styrene-based monomer unit of the styrene-based resin is 80.0 to 99.9% by mass, and the (meth)acrylic acid unit is It is preferable that the content is 0.1 to 20.0 mass%. However, the total of the content of the styrene-based monomer unit and the (meth)acrylic acid unit is set to 100% by mass. (Meth)acrylic acid is acrylic acid, methacrylic acid, etc., and methacrylic acid is preferable.

The measurement of the content of the (meth)acrylic acid unit in the styrene resin is performed at room temperature. 0.5 g of styrene resin was weighed, dissolved in a mixed solution of toluene/ethanol = 8/2 (volume ratio), neutralized and titrated with 0.1 mol/L ethanol solution of potassium hydroxide, and the end point was detected, and the potassium hydroxide ethanol solution As the amount used, the content based on the mass of the (meth)acrylic acid unit is calculated. On the other hand, an automatic potential difference titration device can be used, and measurement can be performed by AT-510 manufactured by Kyoto Electronics Co., Ltd. (Kyoto Electric Industries Co., Ltd.). The content of the (meth)acrylic acid unit in the styrene-based resin can be adjusted by the composition ratio of the styrene-based monomer and the (meth)acrylic acid monomer as a raw material at the time of polymerization of the styrene-based resin, but within a compatible range (meth) A styrene resin containing an acrylic acid unit and a styrene resin not containing a (meth)acrylic acid unit may be mixed and adjusted.

As the polymerization method of the styrene-based resin, a known styrene polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method may be mentioned. From the viewpoint of quality and productivity, the bulk polymerization method and the solution polymerization method are preferable, and continuous polymerization is preferable. As the solvent, for example, alkyl benzenes such as benzene, toluene, ethylbenzene and xylene, ketones such as acetone and methylethylketone, aliphatic hydrocarbons such as hexane and cyclohexane, and the like can be used.

In the polymerization of the styrenic resin, a polymerization initiator and a chain transfer agent may be used as necessary. As the polymerization initiator, a radical polymerization initiator is preferable, and known and common examples include 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2, Peroxy ketals such as 2-di(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-di(t-amylperoxy)cyclohexane, cumene hydroperoxide, t-butyl hydro Hydroperoxides such as peroxide, alkyl peroxides such as t-butylperoxyacetate, t-amylperoxyisononanoate, t-butylcumylperoxide, di-t-butylperoxide, dicumylperoxide, Dialkyl peroxides such as di-t-hexyl peroxide, peroxy esters such as t-butylperoxyacetate, t-butylperoxybenzoate, t-butylperoxyisopropylmonocarbonate, t-butylper Peroxy carbonates such as oxyisopropyl carbonate and polyether tetrakis (t-butyl peroxy carbonate), N,N'-azobis (cyclohexane-1-carbonitrile), N,N'-azobis (2 -Methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile), N,N'-azobis[2-(hydroxymethyl)propionitrile], etc. are mentioned, These can be used alone or in combination of two or more. Examples of the chain transfer agent include aliphatic mercaptan, aromatic mercaptan, pentaphenylethane, α-methylstyrene dimer and terpinolene.

In the case of continuous polymerization, first, a known complete mixing tank type stirring tank or tower type reactor is used in the polymerization process, and the polymerization reaction is controlled by adjusting the polymerization temperature so that the target molecular weight, molecular weight distribution, and reaction conversion rate are achieved. The polymerization solution containing the polymer that has passed through the polymerization process is transferred to a devolatilization process, and unreacted monomers and polymerization solvents are removed. The devolatilization process consists of a vacuum devolatilizer with a heater or a devolatilization extruder with a vent. The molten polymer that has gone through the devolatilization process is transferred to the granulation process. In the granulation process, the molten resin is extruded from a porous die into a strand shape, and processed into a pellet shape by a cold cut method, an air hot cut method, or an underwater hot cut method.

<<Phosphorous antioxidant/phenolic antioxidant>>

The styrenic resin composition of the present invention contains at least one of a phosphorus antioxidant and a phenolic antioxidant as an essential component. Preferably it contains both a phosphorus antioxidant and a phenolic antioxidant.

The phosphorus antioxidant is preferably contained in an amount of 0.02 to 1% by mass, more preferably 0.02 to 0.50% by mass, and still more preferably 0.02 to 0.30% by mass in 100% by mass of the styrene resin composition. In addition, the phenolic antioxidant is preferably contained in an amount of 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 resin composition. This is because when a phosphorus-based or phenol-based antioxidant is added in the above content, long-term uniform surface luminescence is excellent. The content of the phosphorus antioxidant and the phenolic antioxidant in 100% by mass of the styrene resin composition is specifically, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 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 mass%, and may be in the range between any two of the numerical values exemplified herein.

Phosphorus antioxidants are phosphorous acid esters which are trivalent phosphorus compounds. Phosphorous antioxidants are, for example, tris(2,4-di-tert-butylphenyl)phosphite, 2,2'-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2 -Ethylhexyloxy) phosphorus, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, 4,4'-biphenylenediphosphinic acid tetrakis (2,4-di-tert-butylphenyl) , 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, cyclic Neopentanetetraylbis(2,4-di-t-butylphenylphosphite), distearylpentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, bis-[2-methyl-4,6 -Bis-(1,1-dimethylethyl)phenyl]ethylphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakis(2,4-di-tert- Butyl-5-methylphenyl)-4,4'-biphenylenediphosphonite, and the like. As the phosphorus antioxidant, those excellent in hydrolysis resistance are preferable, and tris(2,4-di-tert-butylphenyl)phosphite, 2,2'-methylenebis(4,6-di-tert-butyl-1- Phenyloxy) (2-ethylhexyloxy) phosphorus, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) Si)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane is preferred. Particularly preferably, it is tris(2,4-di-tert-butylphenyl)phosphite. Phosphorus antioxidants may be used alone, but may be used in combination of two or more.

A phenolic antioxidant is an antioxidant having a phenolic hydroxyl group in a basic skeleton. Phenolic antioxidants are, for example, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,9-bis[2-[3-(3- tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, ethylenebis(oxyethylene)bis [3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 4,6-bis(octylthiomethyl)-o-cresol, 4,6-bis[(dodecylthio) Methyl]-o-cresol, 2,4-dimethyl-6-(1-methylpentadecyl)phenol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)pro Cypionate], DL-α-tocopherol, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-[1-(2- Hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenylacrylate, 4,4'-thiobis(6-t-butyl-3-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), bis- [3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid]-glycol ester, etc. are mentioned. Preferably, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,9-bis[2-[3-(3-tert-butyl-4- Hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, ethylenebis(oxyethylene)bis[3-(5- tert-butyl-4-hydroxy-m-tolyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Phenolic antioxidants may be used alone, but may be used in combination of two or more.

As described above, there are a wide variety of phosphorus antioxidants and phenolic antioxidants, but among them, phosphorus antioxidants are at least one selected from (B1-1) to (B1-4) shown below, and phenolic antioxidants It is particularly preferably one or more 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-phenyloxy)(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-tetraoxa-3,9-diphosphaspiro[5.5] Cannes

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

(B2-2) 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8 ,10-tetraoxaspiro[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]

As a method of adding a phosphorus antioxidant and a phenolic antioxidant, a method of adding and mixing a styrene resin in a polymerization process, a devolatilization process, a granulation process, an extruder or injection molding machine during molding processing, and a high concentration of a hydrophilic additive. A method of diluting and mixing the resin composition adjusted to at a desired content with an additive-free styrene resin, etc. are mentioned, and it is not particularly limited.

<<Anthraquinone compound>>

The styrenic resin composition of the present invention contains an anthraquinone compound as an essential component. The content of the anthraquinone compound relative to the total mass of the resin component in the styrene resin composition 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. This is because when the anthraquinone-based compound is added in the above content, the initial and long-term uniform surface luminescence is excellent. The content of the anthraquinone compound is specifically, 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, and may be within the range between any two of the numerical values exemplified herein .

As an anthraquinone compound, the following are mentioned, for example. In addition, the name exemplified 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, Solvent Violet37, Disperse Violet26, Disperse Violet28, Disperse Violet31, Disperse Violet31 Green3, Solvent Green20, Solvent Green28.

<<Other additives>>

The styrenic resin composition may contain mineral oil within a range that does not impair the colorless transparency of the present invention. Further, additives such as internal lubricants such as stearic acid and ethylenebis stearylamide, sulfur-based antioxidants, lactone-based antioxidants, ultraviolet absorbers, hindered amine stabilizers, antistatic agents, and external lubricants may be contained. Further, as the external lubricant, ethylenebis stearylamide is preferable, and the content is preferably 30 to 200 ppm in the resin composition.

The ultraviolet absorber has a function of suppressing deterioration or coloring caused by ultraviolet rays, for example, benzophenone-based, benzotriazole-based, triazine-based, benzoate-based, salicylate-based, cyanoacrylate-based, oxalic anilide Ultraviolet absorbers, such as a system, a malonic acid ester system, and a formamidine system, are mentioned. These can be used alone or in combination of two or more, and a light stabilizer such as hindered amine may be used in combination.

The styrenic resin composition of the present invention may be molded by a molding method according to a purpose such as injection molding, extrusion molding, compression molding, and blow molding, and the shape is not limited. For example, if it is a plate-shaped molded article, it can be processed into a light guide plate or the like. The obtained molded article is used as a member for optics that functions by transmitting light into a molded article such as a light guide plate. An optical member such as a light guide plate has a long transmission distance (optical path length) of light, so it is preferable to have excellent uniform light emission properties. Here, excellent uniform light emission means that the material has excellent transmittance and a small wavelength dependence of light absorption.

The transmittance is preferably 80% or more, more preferably 82.5% or more, and even more preferably 84% or more, with an average transmittance of 380 nm to 780 nm in the optical path length of 115 mm. However, the above average transmittance is obtained by injection molding at a cylinder temperature of 230°C and a mold temperature of 50°C. From a 127 × 127 × 3 mm thick plate-shaped molded product, a 115 × 85 × 3 mm thick specimen is cut out and the cross section is polished by buffing It is to be measured using a test piece having a mirror surface on the prepared cross section. Further, the absolute value of the difference between the average transmittance after storage at 80°C for 1000 hours and the initial period is preferably 2.0% or less, more preferably 1.5% or less, and further preferably 1.2% or less.

The wavelength dependence of the absorption rate of light can be evaluated by, for example, a ratio (t580/t480) of a transmittance of 480 nm (t480) and a transmittance of 580 nm (t580). 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 even more preferably 0.98 <t580/t480 <1.02. Here, the small wavelength dependence of the absorption rate of light means that the ratio (t580/t480) is in principle close to 1. Specifically, the ratio (t580/t480) is, for example, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, and may be within a range between any two of the numerical values exemplified herein.

The transmittance of the optical path length of 115 mm was measured in the following steps. Using the pellets of the styrenic resin composition, injection molding was performed at a cylinder temperature of 230°C and a mold temperature of 50°C, and a plate-shaped molded article having a thickness of 127 × 127 × 3 mm was molded. Here, samples for evaluating long-term thermal stability were stored in an oven at 80° C. for 1000 hours. Next, a test piece having a thickness of 115 × 85 × 3 mm was cut out from the plate-shaped molded article, the cross-section was polished by buffing, and a plate-shaped molded article having a mirror surface in the cross-section was created. For the plate-shaped molded article after polishing, using a UV-visible spectrophotometer V-670 manufactured by Nippon Bunko Co., Ltd., for incident light with a diffusing angle of 0° with a size of 20 × 1.6 mm and a wavelength of 350 nm at an optical path length of 115 mm The spectral transmittance of ~ 800 nm was measured.

The light guide plate is a member that has a function of injecting light from the end face (side) of a plate-shaped molded product and guiding light to the front (light emitting surface) of the molded product by a reflective pattern formed on the rear (non-luminous surface) of the molded product to emit light. . The reflection pattern can be formed by a method such as a screen printing method, an injection molding method, a laser method, or an ink jet method. When processing from a plate-shaped molded article to a light guide plate, it is preferable to polish the incident surface or the entire end surface of the light to make it a mirror surface. Further, in order to increase the uniformity of the outgoing light, a prism pattern or the like can be formed on the entire surface (light emitting surface) of the plate-shaped molded article. The pattern on the front or rear surface of the plate-shaped molded article can be formed at the time of molding the plate-shaped molded article. For example, the pattern can be formed by a mold shape in injection molding and a roll transfer in extrusion molding.

[Example]

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

(Production of styrene resin)

A polymerization process was formed by connecting the first reactor, which is a completely mixed stirring tank, the second reactor, and the third reactor, which is a plug flow reactor having a static mixer, in series, and the conditions shown in Table 1 Manufacturing was carried out. The capacity of each reactor was 39 liters for the first reactor, 39 liters for the second reactor, and 16 liters for the third reactor. A raw material solution was prepared with the raw material composition shown in Table 1, and the raw material solution was continuously supplied to the first reactor at the flow rate shown in Table 1. The polymerization initiator was added to the raw material solution so that the concentration (concentration based on mass relative to the total amount of raw styrene and methacrylic acid) shown in Table 1 was added at the inlet of the first reactor, and uniformly mixed. The polymerization initiators listed in Table 1 are as follows.

Polymerization initiator: 2,2-di(4,4-t-butylperoxycyclohexyl)propane (PERTETRA A manufactured by Nichiyu Corporation was used.)

On the other hand, in the 3rd reactor, a temperature gradient was given along the flow direction, and it adjusted so that it might become the temperature of Table 1 at the middle part and the outlet part.

Subsequently, the solution containing the polymer continuously taken out from the third reactor was introduced into a vacuum devolatilization tank equipped with a preheater consisting of two stages in series, and the temperature of the preheater was adjusted to the resin temperature shown in Table 1. By adjusting and adjusting to the pressure shown in Table 1, unreacted styrene and ethylbenzene were separated, then extruded into a strand shape with a porous die, and the strand was cooled and cut by a cold cut method to pelletize.

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

In the content shown in Table 2, (a) a styrene resin PS-1, (b) a phosphorus antioxidant/phenolic antioxidant, and (c) an anthraquinone compound were mixed at a cylinder temperature of 230°C using a single screw extruder having a screw diameter of 40 mm. And melt-kneading at a screw rotation speed of 100 rpm to obtain a pellet. The phosphorus antioxidant and phenolic antioxidant of (b) used in Table 2, respectively, 2,2'-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phos Porous (ADEKA STAB HP-10 manufactured by ADEKA Corporation), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate (Irganox 1076 manufactured by BASF Japan Corporation), and (c) The anthraquinone compound of is Solvent Violet 33 (Mitsubishi Chemical Co., Ltd. Blue J).

Further, using the obtained pellets, injection molding was performed at a cylinder temperature of 230°C and a mold temperature of 50°C, and a plate-shaped molded article having a thickness of 127 × 127 × 3 mm was molded. In order to evaluate long-term thermal stability, the obtained molded article was stored in an oven at 80°C for 1000 hours. In order to evaluate the optical properties of the initial molded product before storage and the molded product after storage, a 115 × 85 × 3 mm thick test piece is cut out of a plate-shaped molded product, the cross section is polished by buffing, and a plate-shaped molded product having a mirror surface in the cross section. I wrote. For the plate-shaped molded article after polishing, using a UV-visible spectrophotometer V-670 manufactured by Nippon Bunko Co., Ltd., in incident light with a size of 20 × 1.6 mm and a spreading angle of 0°, the optical path The spectral transmittance at a wavelength of 350 nm to 800 nm at 115 mm in length was measured.

In Table 2, each evaluation is indicated by the following criteria. In addition, ×, △, ○, ◎ are set, and × is the lowest, ◎ is the most excellent, and evaluation increases in the order of ×, △, ○, ◎.

Permeability

◎: transmittance of 84% or more

○: transmittance of 82.5% or more and less than 84%

△: transmittance of 80% or more and less than 82.5%

×: 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 luminescence

It is an item in which two evaluations of transmittance and wavelength dependence were evaluated together.

◎: Both transmittance and wavelength dependence are ◎

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

△: Both transmittance and wavelength dependence are △ or more, and at least one is △

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

Long-term uniform surface luminescence

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

◎: Initial uniform surface luminance ◎ In addition, uniform surface luminance after a long-term thermal stability test is greater than or equal to ○

○: Initial uniform surface luminescence ○ In addition, uniform surface luminescence after a long-term thermal stability test is △ or more

△: Initial uniform surface luminance △ In addition, uniform surface luminance after long-term thermal stability test △

×: 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 has excellent initial uniform surface luminescence and long-term uniform surface luminescence.

[Industrial availability]

The optical styrenic resin composition and molded article of the present invention have excellent initial uniform surface luminescence and long-term uniform surface luminescence, for example, a light guide plate for TVs, desk PCs, notebook PCs, mobile phones, car navigation systems, etc. It can be used suitably for the purpose.

Claims (5)

(a) a styrene resin, (b) a phosphorus antioxidant and/or a phenolic antioxidant, and (c) an anthraquinone compound,
The content of (b) in 100% by mass of the styrene resin composition is 0.02 to 1% by mass,
The content of (c) relative to the total mass of the resin component is 0.1 to 90 ppb, characterized in that the optical styrenic resin composition. The method of claim 1,
Optical styrenic resin composition, characterized in that the average transmittance at a wavelength of 380 nm to 780 nm at a length of 115 mm is 80% or more (however, the average transmittance is 127 obtained by injection molding at a cylinder temperature of 230°C and a mold temperature of 50°C. A test piece having a thickness of 115 × 85 × 3 mm was cut out of a plate-shaped molded article having a thickness of × 127 × 3 mm, and the cross-section was polished by buffing, and the resulting cross-section was measured using a test piece having a mirror surface). The method according to claim 1 or 2,
A styrenic resin composition for optics, characterized in that the ratio of the transmittance at a wavelength of 480 nm (t480) and the transmittance at a wavelength of 580 nm (t580) has the following relationship:
0.96 <t580/t480 <1.04. (a) a styrene resin, (b) a phosphorus antioxidant and/or a phenolic antioxidant, and (c) an anthraquinone compound,
The content of (b) in 100% by mass of the styrene resin composition is 0.02 to 1% by mass,
The average transmittance at a wavelength of 380nm to 780nm at a length of 115mm is 80% or more (however, the average transmittance is 127 × 127 × 3 mm thick plate-shaped molded product obtained by injection molding at a cylinder temperature of 230°C and a mold temperature of 50°C. A test piece with a thickness of 115 × 85 × 3 mm is cut out and the cross section is polished by buffing, and the resulting cross section is measured using a test piece having a mirror surface),
A styrenic resin composition for optics, characterized in that the ratio of the transmittance at a wavelength of 480 nm (t480) and the transmittance at a wavelength of 580 nm (t580) has the following relationship:
0.96 <t580/t480 <1.04. An optical component comprising the styrene-based resin composition for optics according to claim 1.