JP7844962B2 - Thermoplastic resin composition and molded article obtained by molding therefrom - Google Patents

Description

This invention relates to a thermoplastic resin composition that, when molded, exhibits good light transmittance, low phase difference, reduced delamination, and excellent surface appearance, as well as a molded article formed therefrom.

Polycarbonate is generally manufactured using raw materials derived from petroleum resources. However, in recent years, concerns about the depletion of petroleum resources have led to a demand for polycarbonate made from raw materials obtained from biomass resources such as plants. Furthermore, given concerns that increased carbon dioxide emissions and accumulation will contribute to global warming and climate change, there is a need for the development of polycarbonate made from plant-derived monomers that is carbon neutral even after disposal. In particular, for applications requiring high impact resistance and low haze, such as in the building materials, electrical and electronics, automotive, optical components, and general merchandise sectors, there is a growing demand for resin compositions that exhibit excellent impact resistance and low haze when molded into products.

Conventionally, various polycarbonates have been developed using plant-derived monomers as raw materials. For example, it has been proposed to use isosorbide as a plant-derived monomer and obtain polycarbonate by transesterification with diphenyl carbonate (Patent Document 1).
When applied to fields such as office automation equipment and optical components, the resulting molded body made of thermoplastic resin exhibits a large phase difference, which may cause distortion such as double or blurred images when viewed through the molded body. Therefore, it is necessary to reduce the phase difference.
Here, a method has been proposed to reduce the phase difference by alloying isosorbide polycarbonate polymer with methacrylic resins such as methacrylic resin and phenylmethacrylic resin (Patent Document 2).

British Patent No. 1079686 Japanese Patent Publication No. 2021-088651

Incidentally, while the invention described in Patent Document 2 addresses the reduction of phase difference, it had the problem of delamination occurring when the gate portion of the molded body obtained in the injection molding process was cut. Delamination can reduce product strength. Furthermore, it also had the problem of surface appearance defects such as flow marks.

Therefore, this invention aims to solve these problems and provide a thermoplastic resin composition that uses environmentally friendly raw materials, has excellent light transmittance, low phase difference, reduced delamination, and superior surface appearance, as well as a molded article formed therefrom.

As a result of their investigations, the inventors discovered that a thermoplastic resin composition containing a polycarbonate resin (A) containing structural units derived from a specific dihydroxy compound, a compatible resin consisting of at least two specific resins that are compatible with each other, and an elastomer (D) having a core-shell structure, results in a molded article with excellent light transmittance, low phase difference, reduced delamination, and superior surface appearance. This led to the completion of the present invention.

In other words, the gist of this invention is as follows:
[1] A thermoplastic resin composition comprising a polycarbonate resin (A) containing a constituent unit derived from a dihydroxy compound represented by the following general formula (1), a resin (B) having a constituent unit (b) derived from a (meth)acrylic acid ester monomer component, a resin (C) having at least one constituent unit selected from a constituent unit (c1) derived from acrylonitrile and a constituent unit (c2) derived from an aromatic vinyl monomer, and an elastomer (D) having a core-shell structure, wherein resin (B) and resin (C) are mutually compatible, and the weight ratio of resin (B) to resin (C) is B:C = 99:1 to 1:99.

[2] The thermoplastic resin composition according to [1], wherein the resin (C) is a resin (C1) having both constituent units (c1) and constituent unit (c2).
[3] The thermoplastic resin composition according to [1] or [2], wherein the resin (C) is an acrylonitrile styrene copolymer.
[4] The thermoplastic resin composition according to any one of [1] to [3], wherein the elastomer (D) is obtained by graft copolymerizing copolymerizable monomer components with respect to a core layer as a shell layer, and the monomer components include at least one monomer selected from (meth)acrylic acid and (meth)acrylic acid esters.

[5] The thermoplastic resin composition according to any one of [1] to [4], wherein when the total amount of resin (A), resin (B), resin (C), and elastomer (D) is 100 parts by weight, the total amount of resin (B) and resin (C) is 1 part by weight or more and 50 parts by weight or less, and the amount of elastomer (D) is 1 part by weight or more and 20 parts by weight or less.
[6] The thermoplastic resin composition according to any one of [1] to [5], wherein the content ratio of resin (B) to resin (C) is B:C = 99:1 to 65:35 by weight.

[7] A thermoplastic resin composition comprising a polycarbonate resin (A) containing a structural unit derived from a dihydroxy compound represented by the following general formula (1), a resin (B) having a structural unit (b) derived from a (meth)acrylic acid ester monomer component, a resin (C1') consisting only of structural units derived from both acrylonitrile (c1) and aromatic vinyl monomers (c2), and an elastomer (D) having a core-shell structure, wherein the weight ratio of resin (B) to resin (C1') is B:C1' = 99:1 to 1:99.

A molded article obtained by molding a thermoplastic resin composition according to any one of items [8], [1], to [7].
[9] A method for producing a thermoplastic resin composition comprising the steps of mixing a polycarbonate resin (A) containing a constituent unit derived from a dihydroxy compound represented by the following general formula (1), a resin (B) having a constituent unit (b) derived from a (meth)acrylic acid ester monomer component, a resin (C) having at least one constituent unit selected from a constituent unit (c1) derived from acrylonitrile and a constituent unit (c2) derived from an aromatic vinyl monomer, and an elastomer (D) having a core-shell structure, wherein the weight ratio of resin (B) to resin (C) is B:C = 99:1 to 1:99.

[10] The resin (C) is a resin (C1') consisting only of both constituent units (c1) derived from acrylonitrile and constituent units (c2) derived from aromatic vinyl monomers, as described in [9].
[11] The method for producing the thermoplastic resin composition described in [9], wherein the resin (B) and resin (C) are mutually compatible.

According to the present invention, molded articles formed from the resulting thermoplastic resin composition exhibit excellent light transmittance, low phase difference, reduced delamination, and superior surface appearance.

The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example (representative example) of an embodiment of the present invention, and the present invention is not limited to the following unless it exceeds the gist of the invention.
The present invention relates to a thermoplastic resin composition comprising a specific polycarbonate resin (A) (hereinafter sometimes simply referred to as "polycarbonate resin (A)" or "resin (A)"), a predetermined resin (B) (hereinafter sometimes simply referred to as "resin (B)"), a resin (C) (hereinafter sometimes simply referred to as "resin (C)"), and an elastomer (D) having a core-shell structure (hereinafter sometimes simply referred to as "elastomer (D)"), and a molded article containing this thermoplastic resin composition.

<Polycarbonate resin (A)>
The polycarbonate resin (A) used in the present invention is a polycarbonate resin containing a constituent unit (a) derived from a dihydroxy compound represented by the following formula (1).

Examples of dihydroxy compounds represented by formula (1) above include isosorbide, isomannide, and isoidette, which are stereoisomers of each other. These may be used individually or in combination of two or more. Among these, isosorbide, obtained by dehydration condensation of sorbitol produced from various starches that are abundant and readily available as plant-derived resources, is most preferred in terms of ease of acquisition and production, moldability, heat resistance, impact resistance, surface hardness, and carbon neutrality.

The dihydroxy compound represented by formula (1) above has a cyclic ether structure and is therefore easily oxidized by oxygen. Therefore, during storage and manufacturing, it is crucial to prevent decomposition by oxygen by ensuring that moisture is not present, using oxygen absorbers, and handling under a nitrogen atmosphere. For example, when isosorbide is oxidized, decomposition products such as formic acid may be generated. Using isosorbide containing these decomposition products as a raw material for polycarbonate resin production may lead to discoloration of the resulting polycarbonate resin and thermoplastic resin composition, significantly degrade its physical properties, and even affect the polymerization reaction, potentially preventing the acquisition of high molecular weight polymers.

The polycarbonate resin (A) used in the present invention is not particularly limited as long as it contains the constituent unit (a) derived from the dihydroxy compound represented by formula (1) above. However, it may be a homopolycarbonate resin that substantially contains only the constituent unit (a) as the constituent unit of the resin, or a copolymerized polycarbonate resin that further contains constituent units other than constituent unit (a). From the viewpoint that the molded article obtained from the thermoplastic resin has superior impact resistance, it is preferable that the polycarbonate resin (A) is a copolymerized polycarbonate resin. When the polycarbonate resin (A) is a copolymerized polycarbonate resin, the content ratio of constituent unit (a) in the polycarbonate resin (A) is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more, based on the total constituent units derived from the dihydroxy compound in the polycarbonate resin (A). Furthermore, it is preferably 90 mol% or less, more preferably 80 mol% or less, and particularly preferably 70 mol% or less. If the amount of constituent units (a1) derived from other dihydroxy compounds in the polycarbonate resin (A) is too low, the heat resistance may be insufficient; if it is too high, the impact resistance may be insufficient.

The polycarbonate resin (A) used in the present invention may be a copolymerized polycarbonate resin containing, in addition to the constituent unit (a) derived from the dihydroxy compound represented by formula (1), one or more dihydroxy compounds selected from the group consisting of aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, aromatic bisphenols, and ether group-containing dihydroxy compounds other than the dihydroxy compound represented by formula (1) (hereinafter sometimes referred to as "other dihydroxy compounds"). This copolymerized polycarbonate resin can improve impact resistance. Among these constituent units (a1), one or more dihydroxy compounds selected from the group consisting of aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, and aromatic bisphenols are preferred. Furthermore, from the viewpoint of light resistance of the polycarbonate resin, dihydroxy compounds that do not have an aromatic ring structure in their molecular structure, i.e., aliphatic dihydroxy compounds and/or alicyclic dihydroxy compounds, are preferred, and when heat resistance is also considered, alicyclic dihydroxy compounds are the most preferred.

The aforementioned aliphatic dihydroxy compound may be either a linear aliphatic dihydroxy compound or a branched aliphatic dihydroxy compound. Examples include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

Examples of the aforementioned alicyclic dihydroxy compounds include 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2,6-decalingimethanol, 1,5-decalingimethanol, 2,3-decalingimethanol, 2,3-norbornanedimethanol, 2,5-norbornanedimethanol, 1,3-adamantanedimethanol, and limonene.

The aforementioned aromatic bisphenols include 2,2-bis(4-hydroxyphenyl)propane [=bisphenol A], 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyphenyl)pentane, 2,4'-dihydroxy-diphenylmethane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-nitrophenyl)methane, and 1,1-bis(4-hydroxyphenyl) Examples include s(4-hydroxyphenyl)ethane, 3,3-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 9,9-bis(4-(2-hydroxyethoxy-2-methyl)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, and 9,9-bis(4-hydroxy-2-methylphenyl)fluorene.

Examples of the aforementioned ether group-containing dihydroxy compounds include diethylene glycol, triethylene glycol, polyethylene glycol (molecular weight 150-2000), poly-1,3-propylene glycol, and polytetramethylene glycol.

When the polycarbonate resin (A) used in the present invention contains structural units (a1) derived from the aforementioned other dihydroxy compounds, the content of these units is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more, in terms of the total dihydroxy compound-derived structural units in the polycarbonate resin (A). Furthermore, 90 mol% or less is preferred, more preferably 80 mol% or less, and particularly preferably 70 mol% or less. If the amount of structural units (a1) derived from the other dihydroxy compounds in the polycarbonate resin (A) is too low, impact resistance may be insufficient; if it is too high, heat resistance may be insufficient.

From the viewpoint of optical properties, it is preferable that the polycarbonate resin (A) used in the present invention does not contain aromatic components as constituent units. That is, it is preferable to use only compounds composed of non-aromatic structures as copolymer monomers. If aromatic components are included in the polymer's main chain, there is a concern that the weather resistance, transparency, and phase difference of the resin composition may deteriorate. By employing the aforementioned other constituent units that do not contain aromatic components, it is possible to prevent the incorporation of aromatic components into the main chain originating from those constituent units.

On the other hand, in order to ensure optical properties while balancing them with heat resistance, mechanical properties, etc., it is sometimes effective to incorporate aromatic components into the main chain or side chains of the polymer. From the viewpoint of balancing various properties, the content of constituent units containing aromatic groups in the resin is preferably 30 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, and particularly preferably 1 mol% or less.

Furthermore, the polycarbonate resin (A) of the present invention can be a mixture of two or more types. By including two types—one containing 40% by weight or more of the constituent unit (a) derived from the dihydroxy compound represented by formula (1) above, and another containing less than 40% by weight—the effect of reducing delamination during injection molding can be further enhanced. In this case, the content ratio of the other dihydroxy compound-derived constituent unit (a1) in the polycarbonate resin (A) is equally preferable as long as it is within the above range when averaged according to the content of each polycarbonate resin corresponding to polycarbonate resin (A).

The polycarbonate resin (A) used in this invention can be manufactured using generally accepted methods for producing polycarbonate resins. This method may be either a solution polymerization method using phosgene or a melt polymerization method in which a dihydroxy compound reacts with a dihydroxy carbonate. However, a melt polymerization method is preferred, in which a dihydroxy compound containing the dihydroxy compound represented by formula (1) is reacted with a dihydroxy carbonate, which has lower environmental toxicity, in the presence of a polymerization catalyst. Furthermore, known alkali metal compounds and/or alkaline earth metal compounds are used as polymerization catalysts (transesterification catalysts) in melt polymerization. It is also possible to use basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds in combination with alkali metal compounds and/or alkaline earth metal compounds as auxiliary agents.

The polycarbonate resin (A) used in this invention can be produced by transesterifying a dihydroxy compound, including the dihydroxy compound represented by formula (1), with a diphenyl carbonate or other diester, as described above. More specifically, it is obtained by transesterifying and removing by-products such as monohydroxy compounds from the system. In this case, melt polymerization is usually carried out by transesterification in the presence of a transesterification catalyst.

Examples of transesterification catalysts (hereinafter sometimes referred to as "catalysts") that can be used in the production of the polycarbonate resin (A) used in the present invention include, for example, basic compounds such as metal compounds of Group 1 or Group 2 (hereinafter simply referred to as "Group 1" or "Group 2") of the long-period periodic table (Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005), basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds. Among these, Group 1 metal compounds and/or Group 2 metal compounds are preferably used, and Group 2 metal compounds are particularly preferred from the viewpoint of transparency and weather resistance.

While it is possible to use basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds in combination with Group 1 and/or Group 2 metal compounds as auxiliary compounds, it is particularly preferable to use only Group 1 and/or Group 2 metal compounds.
Furthermore, while Group 1 and/or Group 2 metal compounds are usually used in the form of hydroxides, or salts such as carbonates, carboxylates, and phenolic salts, hydroxides, carbonates, and acetates are preferred due to their availability and ease of handling, and acetates are preferred from the viewpoint of color and polymerization activity.

Examples of Group 1 metal compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, cesium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium phenylborohydrate, potassium phenylborohydrate, and Examples include lithium borodenoid, cesium boron phenylide, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dicesium hydrogen phosphate, disodium phenyl phosphate, dipotassium phenyl phosphate, dilithium phenyl phosphate, dicesium phenyl phosphate, sodium, potassium, lithium, and cesium alcoholates and phenolates, and disodium, dipotassium, dilithium, and dicesium salts of bisphenol A. Among these, cesium compounds and lithium compounds are preferred.

Examples of Group 2 metal compounds include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate. Among these, magnesium compounds, calcium compounds, and barium compounds are preferred, and magnesium compounds and/or calcium compounds are even more preferred.

Examples of basic boron compounds include sodium salts, potassium salts, lithium salts, calcium salts, barium salts, magnesium salts, or strontium salts of tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenylboron, tributylbenzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, and butyltriphenylboron.

Examples of basic phosphorus compounds include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, or quaternary phosphonium salts.
Examples of basic ammonium compounds include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide, and butyltriphenylammonium hydroxide.

Examples of amine compounds include 4-aminopyridine, 2-aminopyridine, N,N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, and aminoquinoline.

Among the above, it is preferable to use at least one metal compound selected from the group consisting of Group 2 metal compounds as a catalyst in order to obtain a polycarbonate resin (A) with excellent various physical properties such as transparency, hue, and light resistance.
Furthermore, in order to make the transparency, hue, and light resistance of the polycarbonate resin (A) particularly excellent, it is preferable that the catalyst is at least one metal compound selected from the group consisting of magnesium compounds, calcium compounds, and barium compounds, and it is particularly preferable that the catalyst is at least one metal compound selected from the group consisting of magnesium compounds and calcium compounds.

The amount of catalyst used is preferably 0.1 to 300 μmol, more preferably 0.1 to 100 μmol, even more preferably 0.5 to 50 μmol, and particularly preferably 1 to 25 μmol, in terms of metal equivalent, per mole of the total dihydroxy compound used in the reaction.
When using a compound containing at least one metal selected from the group consisting of Group 2 metals, the amount of metal, in terms of metal equivalent, is preferably 0.1 μmole or more, more preferably 0.5 μmole or more, and most preferably 0.7 μmole or more, per mole of total dihydroxy compound used in the reaction. The upper limit is preferably 20 μmole, more preferably 10 μmole, most preferably 3 μmole, and most preferably 2.0 μmole.

If too little catalyst is used, the polymerization activity necessary to produce the polycarbonate resin (A) with the desired molecular weight may not be obtained, potentially resulting in insufficient fracture energy. Conversely, if too much catalyst is used, not only will the color of the resulting polycarbonate resin (A) deteriorate, but by-products may be generated, leading to decreased fluidity and increased gel formation, which can cause brittle fracture and make it difficult to produce polycarbonate resin (A) of the target quality.

In the thermoplastic resin composition of the present invention, the amount of catalyst metal used is derived from the catalyst used in the production of polycarbonate resin and is included in the thermoplastic resin composition. Therefore, the amount of catalyst metal used in the thermoplastic resin composition is the same as the amount specified above.
The polymerization reaction can be carried out using any known method, including batch, continuous, or a combination of both.

Furthermore, when manufacturing the polycarbonate resin (A) used in this invention, it is desirable to install a filter to prevent contamination with foreign matter. The filter is preferably installed downstream of the extruder, and the size of the filter's mesh opening (mesh size) is generally preferred to be 100 μm or less, achieving a 99% filtration efficiency. In particular, for applications such as film where even minute foreign matter contamination is undesirable, a size of 40 μm or less is preferred, and even more preferably 10 μm or less.

The extrusion of the polycarbonate resin (A) used in the present invention is preferably carried out in a cleanroom with a cleanliness level higher than Class 7, as defined in JIS B 9920 (2002), and more preferably higher than Class 6, in order to prevent contamination of foreign matter after extrusion.
Furthermore, when cooling the extruded polycarbonate resin (A) to form chips, it is preferable to use cooling methods such as air cooling or water cooling. When using air cooling, it is desirable to use air from which foreign matter has been removed in advance using a HEPA filter or the like to prevent re-adhesion of foreign matter from the air. When using water cooling, it is desirable to use water from which metal components have been removed using an ion exchange resin or the like, and from which foreign matter has been removed using a filter. The mesh size of the filter used is preferably 10 μm to 0.45 μm to achieve a filtration accuracy of 99% removal.

The average molecular weight of the polycarbonate resin (A) used in the present invention can be expressed in terms of reduced viscosity, which is usually preferably 0.30 dL/g or more, and more preferably 0.35 dL/g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL/g or less, more preferably 1.00 dL/g or less, and even more preferably 0.80 dL/g or less.
If the reduced viscosity of polycarbonate resin (A) is too low, the toughness of the resin composition may be low. If the reduced viscosity is too high, the fluidity when molding electrical and electronic equipment components or automotive interior and exterior parts decreases, which tends to reduce productivity and moldability. In addition, the molding temperature may have to be raised above appropriate levels, which may result in a deterioration of color tone.
Furthermore, the reduced viscosity of polycarbonate resin is measured using a Ubbelohde viscous tube at a temperature of 20.0°C ± 0.1°C, after precisely adjusting the polycarbonate resin concentration to 0.6 g/dL using methylene chloride as the solvent.

The glass transition temperature of the polycarbonate resin (A) used in the present invention is preferably 70°C to 145°C, more preferably 80°C to 135°C, and particularly preferably 90°C to 125°C. If the glass transition temperature is below 70°C, the heat resistance will be insufficient, and if it is above 145°C, the fluidity during molding will be insufficient, which may result in the resin composition not filling to the end of the product or a decrease in strength at the weld joint.
The total light transmittance and haze of the polycarbonate resin (A) of the present invention can be measured by the following method.

(1) Pellet production Molten polycarbonate resin is continuously supplied to a twin-screw extruder equipped with three vents and a water injection facility. 0.1 parts by mass of Irganox 1010 (manufactured by BASF Japan Ltd., pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) as an antioxidant, 0.05 parts by mass of Adekastab 2112 (manufactured by ADEKA Corporation, tris(2,4-di-tert-butylphenyl)phosphite), and 0.3 parts by mass of Unistar E-275 (manufactured by NOF Corporation) as a mold release agent are continuously added to 100 parts by mass of the polycarbonate resin. Low molecular weight substances such as phenol are then defolantized under reduced pressure at each vent of the twin-screw extruder, and then pelletized using a pelletizer.

(2) Injection molding The pellets kneaded in a twin-screw extruder are pre-dried at 100°C for 6 hours. These pellets are then molded into 100 mm x 100 mm x 2 mm thick flat plates using a J85AD injection molding machine manufactured by Japan Steel Works Ltd., with a cylinder temperature of 240°C, a molding cycle of 40 seconds, and a mold temperature of 60°C.

(3) Measurement of Haze and Total Light Transmittance Using a NDH2000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd., the haze (%) and total light transmittance (%) of the test piece are measured with a D65 light source. The total light transmittance of the polycarbonate resin (A) of the present invention is preferably 85% or more, more preferably 88% or more, and particularly preferably 90% or more. If this total light transmittance is higher than the above lower limit, the total light transmittance when it is used as a thermoplastic resin composition will be higher. Details of the method for measuring this total light transmittance will be described in the Examples section.

The haze of the polycarbonate resin (A) of the present invention, in accordance with JIS K 7105, is typically 2% or less, preferably 1.5% or less, and most preferably 1% or less. When the haze is within the above range, it is possible to achieve both high total light transmittance and high haze when used as a thermoplastic resin composition.
Furthermore, the thermoplastic resin composition of the present invention may use one type of polycarbonate resin (A) alone, or it may use a mixture of two or more types of polycarbonate resins with different types of constituent units derived from other dihydroxy compounds, copolymerization ratios, physical properties, etc.

<Resin (B)>
The resin (B) used in the present invention is a resin having a constituent unit (b) derived from a (meth)acrylic acid ester monomer component, that is, an acrylic resin.

In this invention, an acrylic resin used is a thermoplastic acrylic resin. Examples of constituent units (b) of the (meth)acrylic acid ester monomer component of this acrylic resin include methyl (meth)acrylate, (meth)acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and norbornyl Examples include (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acroyloxyethyl succinate, 2-(meth)acroyloxyethyl maleate, 2-(meth)acroyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. These may be polymerized individually or used in combination of two or more. Among these, those using at least one of alkyl methacrylate and alkyl acrylate are preferred due to their impact resistance and low haze. Furthermore, other monomers that can be polymerized with these acrylic monomers, such as polyolefin monomers and vinyl monomers, may be used in combination.

In this specification, "(meth)acrylate" means "acrylate" or "methacrylate".
The molecular weight of the acrylic resin is not particularly limited, but if it is in the range of 30,000 to 300,000 in weight-average molecular weight, it is possible to provide a multilayer body that does not produce appearance defects such as uneven flow when molded as a multilayer body, and has excellent mechanical properties and heat resistance.

<Resin (C)>
The resin (C) used in the present invention is a resin having at least one constituent unit selected from a constituent unit (c1) derived from acrylonitrile and a constituent unit (c2) derived from an aromatic vinyl monomer. As this resin (C), a resin (C1) having both constituent units (c1) and (c2) may be used, or a resin having constituent unit (c1) (C2-1) and a resin having constituent unit (c2) (C2-2) may be used in combination.

[Compatibility]
By the way, it is preferable that resin (C) and resin (B) are mutually compatible. Here, "compatible" refers to the property of mixing multiple substances together without separating when mixed.
In the present invention, since resin (B) and resin (C) are mutually compatible, it becomes easier to match the refractive index of resin (A), and the characteristic of maintaining high transparency can be achieved.
The mutual compatibility of resin (B) and resin (C) can be confirmed, for example, by the fact that the thermoplastic resin composition exhibits a glass transition temperature different from that of resin (B) and resin (C).

[Component unit (c1), Component unit (c2)]
Examples of monomers having the aforementioned structural unit (c1) include acrylonitrile. Examples of monomers having the structural unit (c2) include styrene and styrene derivatives such as α-methylstyrene, o-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromstyrene, dibromstyrene, fluorostyrene, and tribromstyrene, with styrene being particularly preferred. Furthermore, these can be used individually or in combination of two or more.

[Resin (C1)]
Resin (C1) is a resin having both constituent units (c1) derived from acrylonitrile and constituent units (c2) derived from aromatic vinyl monomers. A resin (C1) having both of these constituent units and being compatible with resin (B) as described above is a resin (C1') consisting only of constituent units (c1) derived from acrylonitrile and constituent units (c2) derived from aromatic vinyl monomers, specifically an acrylonitrile-styrene copolymer.

[Resin (C2-1), Resin (C2-2)]
The resin (C2-1) is a resin having a constituent unit (c1) derived from acrylonitrile, but not containing the aforementioned constituent unit (c2). An example of this resin (C2-1) is polyacrylonitrile, etc.
Furthermore, the resin (C2-2) is a resin having a constituent unit (c2) derived from an aromatic vinyl monomer, and is a resin that does not contain the aforementioned constituent unit (c1). Examples of this resin (C2-2) include polystyrene and poly-α-methylstyrene.

<Elastomer with a core-shell structure (D)>
The present invention is characterized by containing an elastomer (D) having a core-shell structure. In this specification, "elastomer having a core-shell structure" refers to a core-shell type graft copolymer composed of an innermost layer (core layer) and one or more layers covering it (shell layer), wherein monomer components that can be graft copolymerized with respect to the core layer are graft copolymerized as the shell layer.

In the present invention, it is preferable to use a thermoplastic elastomer (D). Various copolymer resins can be used as thermoplastic elastomers, but those with a glass transition temperature of 0°C or lower are preferred, of which -10°C or lower are preferred, more preferably -20°C or lower, and even more preferably -30°C or lower.
Of these, it is preferable to use an elastomer having a core-shell structure in which the shell contains at least one (meth)acrylic acid or (meth)acrylic acid ester.

More specifically, as the elastomer (D) of the present invention, for example, MBS (methyl methacrylate-butadiene-styrene) copolymer, MABS (methyl methacrylate-acrylonitrile-butadiene-styrene) copolymer, MS (methyl methacrylate-acrylic rubber-styrene) copolymer, alkyl acrylate-methyl methacrylate-styrene copolymer, methyl methacrylate-acrylic-butadiene rubber copolymer, butadiene rubber-methyl methacrylate-alkyl acrylate copolymer, methyl methacrylate-acrylic-butadiene rubber-styrene copolymer, methyl methacrylate-(acrylic-silicone IPN rubber) copolymer, and natural rubber can be used. In combination with the polycarbonate resin, particularly effects of reducing delamination, improving light resistance, and improving impact resistance can be obtained. More preferably, alkyl acrylate-methyl methacrylate-styrene copolymer and butadiene-methyl methacrylate-alkyl acrylate copolymer are used. For example, specific examples of alkyl acrylate-methyl methacrylate-styrene copolymers and butadiene-methyl methacrylate-alkyl acrylate copolymers are not particularly limited, but include the following:

For example, in the case of the alkyl acrylate-methyl methacrylate-styrene copolymer, examples include Kaneka Corporation's product name Kaneace M-590, Mitsubishi Chemical Corporation's products name Metabren W-341, W-377, W-341, and Acrypet IR377, IR441, IR491.
Examples of the butadiene-methyl methacrylate-alkyl acrylate copolymer include Paraloid EXL-2650J and EXL-2690, manufactured by Dow Chemical. These elastomers, consisting of a core-shell structure, may be used individually or in combination of two or more types.

The refractive index difference between the elastomer (D) of the present invention and the resin (A) is preferably ±0.012 or less. Furthermore, from the viewpoint of transparency, ±0.010 or less is more preferable, and ±0.008 or less is particularly preferable.

The elastomer (D) may contain resin (B). While not particularly limited, examples include Acrypet IRK304 and VRL40.

The average particle size of the elastomer (D) of the present invention is preferably 10 to 500 nm. More preferably 30 to 300 nm, even more preferably 50 to 200 nm, and most preferably 50 to 180 nm. An average particle size of 10 nm tends not to provide sufficient impact strength. On the other hand, an average particle size exceeding 500 nm tends to reduce the transparency of the resulting resin composition. The average particle size is measured in the latex state of the rubbery polymer and graft copolymer. The volume-average particle size can be measured using a MICROTRAC U PA150 manufactured by Nikkiso Co., Ltd.

(Polymerization method)
As a polymerization method for the elastomer (D) of the present invention, general polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used. As an example, a polymerization method for butyl acrylate/methyl methacrylate/styrene copolymer will be described. As a method for producing butyl acrylate/methyl methacrylate/styrene copolymer, any of bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization may be used, but emulsion polymerization, i.e., emulsion graft polymerization, is preferred. Specifically, latex is added to a reaction vessel equipped with a stirrer, and then a vinyl monomer, polymerization initiator, and water are added, and if necessary, a chain transfer agent and an oxidation-reduction agent are charged, and the mixture is heated and stirred.

There are no particular restrictions on the types of polymerization initiators, chain transfer agents, and redox agents used here; known agents can be used. Furthermore, there are no particular restrictions on the method of adding each raw material to the reaction vessel; they may be added all at once before polymerization begins, or in stages. Graft polymerization may be carried out in one or more stages, and the monomer composition of each stage may be the same or different. The monomers may also be added all at once, sequentially, or in combination.

When employing emulsion polymerization, known polymerization initiators, namely thermal decomposition type polymerization initiators such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used. Alternatively, a redox type polymerization initiator can be used, combining peroxides such as organic peroxides (e.g., t-butyl peroxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-hexyl peroxide) or inorganic peroxides (e.g., hydrogen peroxide, potassium persulfate, ammonium persulfate), with, if necessary, reducing agents such as sodium formaldehyde sulfoxylate and glucose, transition metal salts such as iron(II) sulfate, chelating agents such as disodium ethylenediaminetetraacetate, and phosphorus-based flame retardants such as sodium pyrophosphate.

When using a redox-type polymerization initiator system, polymerization can be carried out even at low temperatures where the peroxide does not substantially decompose thermally, which is preferable because it allows for a wide range of polymerization temperatures to be set. In particular, it is preferable to use aromatic ring-containing peroxides such as cumene hydroperoxide and dicumyl peroxide as redox-type polymerization initiators. The amount of polymerization initiator used, and the amounts of reducing agents, transition metal salts, chelating agents, etc., used when a redox-type polymerization initiator is used, can be used within known ranges.

When synthesizing butyl acrylate/methyl methacrylate/styrene copolymer by emulsion polymerization, conventionally known polymerization emulsifiers can be used, such as alkali metal salts of higher fatty acids like disproportionated rosinic acid, oleic acid, and stearic acid, or alkali metal salts of phosphoric acid compounds, as well as alkali metal salts of sulfonic acid and sulfuric acid compounds.

When a butyl acrylate/methyl methacrylate/styrene copolymer is obtained by emulsion polymerization, for example, the latex of the butyl acrylate/methyl methacrylate/styrene copolymer can be mixed with an acid such as hydrochloric acid, or a divalent or higher metal salt such as calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, or calcium acetate to solidify the copolymer. After solidification, the copolymer can be separated from the aqueous medium by heat treatment, dehydration, washing, and drying according to a known method (also called the solidification method). Alternatively, the butyl acrylate/methyl methacrylate/styrene copolymer can be precipitated by adding an alcohol such as methanol, ethanol, or propanol, or a water-soluble organic solvent such as acene, to the latex. After separating it from the solvent by centrifugation or filtration, it can be dried and isolated. Alternatively, a method can be used in which a latex containing the impact-resistant agent used in the present invention is mixed with a slightly water-soluble organic solvent such as methyl ethyl ketone to extract the impact-resistant agent component from the latex into the organic solvent layer. After separating the organic solvent layer, the impact-resistant agent component is precipitated by mixing it with water or the like. Furthermore, the latex can also be directly powdered by spray drying.

<Mixing ratio of resin (B) and resin (C)>
The mixing ratio (weight ratio) of resin (B) and resin (C) is preferably 99/1 or less, and more preferably 95/5 or less, in the B/C ratio. If there is too much resin (B), the total light transmittance may decrease and the haze may increase. The lower limit of B/C is preferably 1/99 or more, and more preferably 65/35 or more. If there is too much resin (C), the total light transmittance may decrease and the haze may increase.

<Mixing ratio of resin (A), resin (B), resin (C), and elastomer (D)>
The mixing ratio (weight ratio) of resin (A), resin (B), resin (C), and elastomer (D) is such that, when the total amount of resin (A), resin (B), resin (C), and elastomer (D) is 100 parts by weight, the total amount of resin (B) and resin (C) is preferably 1 part by weight or more, more preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and particularly preferably 20 parts by weight or more. If the total amount of resin (B) and resin (C) is too small, there is a risk that the reduction of the phase difference will be insufficient. Furthermore, the upper limit of the total amount of resin (B) and resin (C) is preferably 50 parts by weight or less, preferably 45 parts by weight or less, and more preferably 40 parts by weight or less. If the total amount of resin (B) and resin (C) is too large, there is a risk that the impact resistance will decrease. Furthermore, the elastomer (D) content is preferably 1 part by weight or more, preferably 3 parts by weight or more, and more preferably 5 parts by weight or more. If the elastomer (D) content is too low, delamination and surface appearance defects may occur. The upper limit for the elastomer (D) content is preferably 20 parts by weight or less, more preferably 18 parts by weight or less, and more preferably 15 parts by weight or less. If the elastomer (D) content is too high, problems such as reduced heat resistance may occur.

<Difference between the refractive index of resin (A) and the refractive index of the mixed resin of resins (B) and (C)>
The difference between the refractive index of resin (A) and the refractive index of the mixed resin of resins (B) and (C), i.e., (refractive index of resin (A)) - (refractive index of the mixed resin of resins (B) and (C)), is preferably within the range of ±0.009, and more preferably within the range of ±0.007. If this difference in refractive index is too large, the total light transmittance may decrease or the haze may increase.

<Method for producing the thermoplastic resin composition according to the present invention>
The thermoplastic resin composition of the present invention can be produced by mixing the above-mentioned resin (A), resin (B), resin (C), and elastomer (D) simultaneously or in any order in predetermined proportions using a mixer such as a tumbler, V-type blender, Nauter mixer, Banbury mixer, kneading roll, or extruder.

<Additives>
The thermoplastic resin composition of the present invention may optionally contain antioxidants, light stabilizers, ultraviolet absorbers, mold release agents, colorants, neutralizing agents, antistatic agents, lubricants, plasticizers, flame retardants, fillers, and the like.

(Release agent)
The thermoplastic resin composition of the present invention may contain a release agent to the extent that it does not impair the objectives of the present invention, for example, to further improve roll separation from the cooling roll during sheet molding, or release from the mold during injection molding.
Examples of such release agents include higher fatty acid esters of monohydric or polyhydric alcohols, higher fatty acids, paraffin wax, beeswax, olefin wax, olefin wax containing carboxyl groups and/or carboxylic acid anhydride groups, silicone oil, organopolysiloxane, and the like. The release agent may be used alone or in combination of two or more types.

The aforementioned higher fatty acid esters are preferably partial or total esters of a monohydric or polyhydric alcohol having 1 to 20 carbon atoms and a saturated fatty acid having 10 to 30 carbon atoms. Examples of such partial or total esters of a monohydric or polyhydric alcohol and a saturated fatty acid include monoglyceride stearate, diglyceride stearate, triglyceride stearate, monosorbite stearate, stearyl stearate, monoglyceride behenic acid, behenyl behenic acid, pentaerythritol monostearate, pentaerythritol tetrastearate, pentaerythritol tetrapelargonate, propylene glycol monostearate, stearyl stearate, palmityl palmitate, butyl stearate, methyl laurate, isopropyl palmitate, biphenyl biphenate, sorbitan monostearate, and 2-ethylhexyl stearate. Among these, monoglyceride stearate, triglyceride stearate, pentaerythritol tetrastearate, and behenyl behenate are preferably used as release agents. From the viewpoint of release properties and transparency, stearic acid esters are more preferable as release agents.

As the stearic acid ester, partial or total esters of stearic acid with substituted or unsubstituted monohydric or polyhydric alcohols having 1 to 20 carbon atoms are preferred. More preferred as such partial or total esters of monohydric or polyhydric alcohols with stearic acid are ethylene glycol distearate, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, stearic acid monosorbite, stearic acid stearyl, pentaerythritol monostearate, pentaerythritol tetrastearate, propylene glycol monostearate, stearyl stearate, butyl stearate, sorbitan monostearate, and 2-ethylhexyl stearate. Among these, stearic acid monoglyceride, stearic acid triglyceride, pentaerythritol tetrastearate, and stearyl stearate are even more preferred, and ethylene glycol distearate and stearic acid monoglyceride are particularly preferred.

As the aforementioned higher fatty acids, saturated fatty acids having 10 to 30 carbon atoms, whether substituted or unsubstituted, are preferred. Among these, unsubstituted saturated fatty acids having 10 to 30 carbon atoms are more preferred. Examples of such higher fatty acids include myristic acid, lauric acid, palmitic acid, stearic acid, and behenic acid. Among these, saturated fatty acids having 16 to 18 carbon atoms are even more preferred. Examples of such saturated fatty acids include palmitic acid and stearic acid, with stearic acid being particularly preferred.

When a mold release agent is used, its amount is usually 0.001 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and usually 2 parts by weight or less, preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, based on 100 parts by weight of the total amount of resin (A), resin (B), and resin (C). If the mold release agent content is excessively high, mold adhesion may increase during molding, potentially requiring more effort to maintain the mold when molding in large quantities, and may also result in defective appearance of the resulting molded product. When the mold release agent content in the thermoplastic resin composition is above the above lower limit, the molded product becomes easier to release from the mold during molding, which has the advantage of making it easier to obtain the molded product.

(Antioxidant)
While general antioxidants used in resins can be used as the aforementioned antioxidant, phosphite-based antioxidants, sulfur-based antioxidants, and phenol-based antioxidants are preferred from the viewpoint of oxidation stability, thermal stability, and jet blackness.

When an antioxidant is added to the thermoplastic resin composition of the present invention, the amount added is usually preferably 0.001 parts by mass or more, more preferably 0.002 parts by mass or more, even more preferably 0.005 parts by mass or more, usually 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of resin (A).
If the amount of antioxidant added is greater than 5 parts by mass, it may contaminate the mold during molding, resulting in a molded product with an inferior surface appearance. On the other hand, if it is less than 0.001 parts by mass, it tends not to provide sufficient improvement in weather resistance testing.

<Phosphite-based antioxidants>
Examples of the phosphite-based antioxidants include triphenyl phosphite, tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, bis(nonylphenyl) pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and distearyl pentaerythritol diphosphite.

Among these, trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite are preferred.
These compounds may be used individually or in combination of two or more.

<Sulfur-based antioxidants>
Examples of the sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, laurylstearyl-3,3'-thiodipropionate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-laurylthiopropionate), glycerol-3-stearylthiopropionate, bis[2-methyl-4-(3-laurylthiopropionyloxy)-5-tert-butylphenyl] sulfide, octadecyl disulfide, mercaptobenzimidazole, 2-mercapto-6-methylbenzimidazole, and 1,1'-thiobis(2-naphthol).
Among these, pentaerythritol tetrakis(3-laurylthiopropionate) is preferred.
These compounds may be used individually or in combination of two or more.

<Phenol-based antioxidants>
Examples of the phenolic antioxidants include triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzyl Examples of compounds include zen, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, tetrakis(2,4-di-tert-butylphenyl)biphenylenediphosphinate, 3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane, 2,6-di-tert-butyl-p-cresol, and 2,6-di-tert-butyl-4-ethylphenol.

Among these compounds, aromatic monohydroxy compounds substituted with one or more alkyl groups having five or more carbon atoms are preferred. Specifically, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene are preferred, and pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is even more preferred.
These compounds may be used individually or in combination of two or more.

(Light stabilizer)
Examples of light stabilizers include hindered amine-based light stabilizers, with a molecular weight of 5000 or less, and more preferably 3000 or less. If the molecular weight exceeds 5000, sufficient weather resistance may not be obtained when the molded product is formed. Furthermore, a molecular weight of 300 or more is preferred, and more preferably 400 or more. If the molecular weight is less than 300, the heat resistance is poor, which may contaminate the mold during molding and prevent the acquisition of molded products with excellent surface appearance.

Furthermore, compounds having a piperidine structure are preferred. The piperidine structure as defined herein is a saturated six-membered ring amine structure, and includes those in which part of the piperidine structure is substituted with substituents. Examples of substituents include alkyl groups having four or fewer carbon atoms, with methyl groups being particularly preferred.
As hindered amine-based light stabilizers, compounds having multiple piperidine structures are particularly preferred, and compounds in which these multiple piperidine structures are linked by ester structures are particularly preferred.

Examples of such light stabilizers include 4-piperidinol, 2,2,6,6-tetramethyl-4-benzoate, bis(2,2,6,6-tetramethyl-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis(2,2,6,6-tetramethylpiperidine-4-carboxylic acid) 1,2,3,4-butanetetrayl, a condensate of 2,2,6,6-tetramethyl-pyreridinol, tridecyl alcohol, and 1,2,3,4-butanetetracarboxylic acid, and 2,2,6,6-tetramethyl-pyreridinol, methanol, and 1,2,3,4-butanetetracarboxylic acid. Condensates of benzoic acid, bis(1,2,3,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester of decandioate, reaction product of 1,1-dimethylethyl hydroperoxide and octane, 1-[2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-(3,5-di-tert-butyl-4,4-hydroxyphenyl)propionyloxy]ethyl]-2, 2,6,6-tetramethylpiperidine, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexanediamine polymer and 2,4,6-trichloro-1,3,5-triazine, Examples include condensates of 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol, and β,β,β,β-tetramethyl-3,9-(2,4,8,10-tetraoxaspiro[5,5]undecane-diethanol; condensates of N,N'-bis(3-aminopropyl)ethylenediamine and 2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine; and condensates of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine.

When a light stabilizer is added to the thermoplastic resin composition of the present invention, the amount added is usually 0.001 parts by mass or more and 5 parts by mass or less, preferably 0.001 parts by mass, per 100 parts by mass of resin (A).
The amount is 0.05 parts by mass or more and 3 parts by mass or less, more preferably 0.01 parts by mass or more and 1 part by mass or less.
If the amount of light stabilizer added is greater than 5 parts by mass, discoloration tends to occur, and even if a coloring agent is added, it is difficult to obtain, for example, a deep and clear jet black. On the other hand, if it is less than 0.001 parts by mass, sufficient weather resistance may not be obtained when used as an interior or exterior part for automobiles.

(UV absorber)
The thermoplastic resin composition of the present invention may contain an ultraviolet absorber to the extent that it does not impair the objectives of the present invention. Examples include 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl-5-chlorobenzotriazole, 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 2,2'-p-phenylenebis(1,3-benzoxazine-4-one). The content of such an ultraviolet absorber is preferably 0.01 to 2 parts by weight per 100 parts by weight of resin (A).

<Physical properties of thermoplastic resin compositions>
The thermoplastic resin composition of the present invention preferably has the following physical properties.
• Total Light Transmittance The thermoplastic resin composition of the present invention preferably has a total light transmittance of 75% or more. In this case, the transparency of the polycarbonate resin composition is even better. From a similar viewpoint, a total light transmittance of 85% or more is particularly preferred. The total light transmittance is measured by the method described below.

• Haze The thermoplastic resin composition of the present invention preferably has a haze of 45% or less, more preferably 25% or less, particularly preferably 15% or less, and most preferably 5% or less. In this case, the transparency of the thermoplastic resin composition is even better. The haze is measured by the method described below.

Phase difference The thermoplastic resin composition of the present invention preferably has a phase difference of 150 nm or less, more preferably 130 nm or less, and particularly preferably 125 nm or less. In this case, the molded article formed from the thermoplastic resin composition has a smaller phase difference, and therefore the effect of suppressing distortion such as double or blurring of the image seen through the molded article is better. The phase difference is measured by the method described later.

<Molded product>
When molding molded articles using the thermoplastic resin composition of the present invention, any molding method can be used, but injection molding, injection compression molding, and injection press molding are preferably used. In addition to the usual cold runner method, a hot runner method can also be used for the runners used. Furthermore, insert molding, in-mold coating molding, two-color molding, sandwich molding, etc., are also possible. In addition, insulated mold molding and rapid heating and cooling mold molding can be used to obtain design advantages.

Next, the present invention will be described in more detail with reference to examples. The present invention is not limited in any way by these examples. First, the evaluation method will be described.

[Evaluation Method]
(1) Refractive Index The pellets were dried at 80°C for 6 hours using a vacuum dryer. Next, the dried pellets were pressed into a press-formed plate (7 mm wide x 15 mm long x 1 mm thick) at 230°C using a mini test press (MP-2FH, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The resulting press-formed plate was cut to the specified dimensions (160 mm wide x 160 mm long x 1 mm thick), and the refractive index nD was measured using an Abbe refractometer (DR-M4, manufactured by Atago Corporation) with a 589 nm (D-line) interference filter.

(2) Measurement of total light transmittance The obtained thermoplastic resin composition pellets were dried in a hot air dryer at 100°C for 6 hours. Next, the dried thermoplastic resin composition pellets were supplied to an injection molding machine (manufactured by Japan Steel Works Ltd.: J85AD type), and an injection-molded plate (width 100 mm × length 100 mm × thickness 2 mm) was molded under the conditions of resin temperature 240°C, mold temperature 60°C, and molding cycle of 40 seconds. The total light transmittance of the obtained injection-molded plate was measured in accordance with JIS K7361-1 using an NDH-7000II manufactured by Nippon Denshoku Industries Ltd.

(3) Haze Measurement Using the same test piece as the total light transmittance measurement described above, the haze of the test piece was measured using the NDH-7000II manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7136.

(4) Pencil hardness measurement Using the same test pieces as in the haze measurement described above, the pencil hardness was measured using a pencil hardness tester manufactured by Mize Testing Machine Co., Ltd. in accordance with JIS K5600-5-4.

(5) Phase difference measurement Using the same test piece as in the pencil hardness measurement described above, the phase difference with respect to a wavelength of 590 nm was measured using the phase difference measuring device "KOBRA WWR/XY" manufactured by Oji Instruments Co., Ltd. The measurement was performed by dividing the sample into a 10 mm x 10 mm mesh, and the average of the phase differences of each divided mesh was taken as the average phase difference.

(6) Delamination Evaluation Using the same test piece as the phase difference measurement described above, the gate portion was visually inspected to check for the presence or absence of delamination, and evaluated in the following three stages. If the degree of delamination is slight, it is possible to design the mold in a way that does not affect the reduction in strength of the molded product, so "◎" or "○" was considered acceptable.
◎: No delamination observed ○: Slight delamination observed (distance of delamination in the MD direction is less than 2 mm)
×: Delamination is observed (the distance of delamination in the MD direction is 2 mm or more).

(7) Surface appearance evaluation Using the same test piece as the phase difference measurement described above, the surface was visually observed to check for the presence or absence of streaky patterns, and evaluated in the following two stages.
○: No streaky pattern observed ×: Streaky pattern observed, resulting in a defective surface appearance

(6) Hue Measurement Using the same test piece as in the phase difference measurement described above, the lightness L* value was measured using the Konica Minolta CM-5 color chromatograph. The measurement was performed using the reflection method with a D65/10 light source and a reflection measurement diameter of φ30 mm to measure the L* value.

Those who met all of the following conditions were considered to have passed.
• Total light transmittance: 75% or higher • Haze: 45% or lower • Pencil hardness: F or higher • Average phase difference: 170 nm or lower • Delamination: ◎ or ○ • Surface appearance: ○

[raw materials]
<Raw materials for polycarbonate resin (A)>
Isosorbide... Manufactured by Rocket Fleuret: POLYSORB, hereinafter referred to as "ISB".
• Cyclohexanedimethanol…Manufactured by Eastman, hereinafter referred to as "CHDM".
• Diphenyl carbonate… Manufactured by Mitsubishi Chemical Corporation, hereinafter referred to as "DPC".

<Resin (B)>
- Polymethyl methacrylate... Manufactured by Mitsubishi Chemical Corporation, product name: Acrypet VH, refractive index: nd = 1.492, hereinafter referred to as "PMMA".
<Resin (C)>
- Acrylonitrile-styrene copolymer resin... Manufactured by Techno UMG, refractive index: nd = 1.569, trade name: Sunrex, hereinafter referred to as "AS".
<Elastomer with a core-shell structure (D)>
• Alkyl acrylate-methyl methacrylate-styrene copolymer… Manufactured by Mitsubishi Chemical Corporation, product name: Acrypet IR-491, refractive index: nd = 1.494, hereinafter referred to as "D-1".
- Alkyl acrylate-methyl methacrylate-styrene copolymer... Manufactured by Kaneka Corporation, product name: Kaneace M-590, refractive index: nd = 1.50, hereinafter referred to as "D-2".
Butadiene-methyl methacrylate-alkyl acrylate copolymer... Manufactured by Dow Chemical Company, trade name Paraloid EXL-2650J, refractive index: nd = 1.51, hereinafter referred to as "D-3".

[Manufacturing of polycarbonate resin (A-1)]
(Manufacturing example 1)
In a polymerization reactor equipped with a stirring blade and a reflux condenser controlled to 100°C, ISB, CHDM, DPC (distilled and purified to a chloride ion concentration of 10 ppb or less), and calcium acetate monohydrate were charged in a molar ratio of ISB/CHDM/DPC/calcium acetate monohydrate = 0.70/0.30/1.00/1.3 × ^10⁻⁶ , and the reactor was thoroughly purged with nitrogen to adjust the oxygen concentration to 0.0005 to 0.001 volume percent.
Next, the mixture was heated with a heat transfer medium, and when the internal temperature reached 100°C, stirring was started, and the contents were melted and homogenized while controlling the internal temperature to maintain 100°C. After that, the heating was increased, and the internal temperature was raised to 210°C in 40 minutes. Once the internal temperature reached 210°C, the pressure was controlled to maintain this temperature, and at the same time, the pressure was reduced to 13.3 kPa (absolute pressure, the same applies below) 90 minutes after reaching 210°C, and this pressure was maintained for another 60 minutes.

The phenol vapor produced as a by-product during the polymerization reaction was guided to a reflux condenser using vapor as a refrigerant, with the inlet temperature controlled to 100°C. The small amounts of dihydroxy compounds and diester carbonates contained in the phenol vapor were returned to the polymerization reactor, and the uncondensed phenol vapor was subsequently guided to a condenser using 45°C hot water as a refrigerant to recover it. The oligomerized contents were then restored to atmospheric pressure, and then transferred to another polymerization reactor equipped with a stirring blade and a reflux condenser controlled in the same manner as described above. Heating and depressurization were started, and the internal temperature reached 220°C and the pressure 200 Pa in 60 minutes.
Subsequently, the internal temperature was reduced to 230°C and the pressure to 133 Pa or less over 20 minutes. Once the predetermined stirring power was reached, the pressure was restored to atmospheric pressure, and the contents were extracted in strand form and processed into carbonate copolymer pellets using a rotary cutter. The obtained resin (A-1) was used in the following examples and comparative examples. The refractive index (nD) of resin (A-1) was 1.50.

[Manufacturing of polycarbonate resin (A-2)]
(Manufacturing example 2)
The resin (A-2) was manufactured in the same manner as in Manufacturing Example 1, except that the molar ratio of ISB and CHDM was set to ISB/CHDM = 0.30/0.70. The obtained resin (A-2) was used in the following examples and comparative examples. The refractive index (nD) of resin (A-2) was 1.50.

[Manufacturing of polycarbonate resin (A-3)]
(Manufacturing example 3)
The resin was manufactured in the same manner as in Manufacturing Example 1, except that CHDM was replaced with TCDDM. The obtained resin (A-3) was used in the following examples and comparative examples. The refractive index (nD) of resin (A-3) was 1.511.

(Examples 1-13, Comparative Examples 1-4, Reference Examples 1-3)
Using resins A (A-1, A-2, A-3), B (PMMA), C (AS), and D (D-1, D-2, D-3) produced in Manufacturing Examples 1 to 3, each component was blended according to the polycarbonate resin composition formulation shown in Table 1. The mixture was extruded in strand form using a twin-screw extruder (LABOTEX30HSS-32) manufactured by Japan Steel Works Ltd., which has two vents, so that the resin temperature at the extruder outlet reached 250°C. After cooling and solidifying with water, it was pelletized using a rotary cutter. At this time, the vents were connected to a vacuum pump and the pressure at the vents was controlled to 500 Pa. Reference Example 3 is based on the formulation of Example 5 and colored black.
The obtained thermoplastic resin compositions were evaluated using the method described above, and the results are shown in Table 1.
The phase difference between PMMA and AS is shown in Reference Examples 1 and 2, and the differences from each embodiment were confirmed.

[result]
From the results described above, it was found that in Examples 1 to 13, sufficiently high transparency and low average phase difference were obtained, interlayer delamination was reduced, and the surface appearance was excellent. In particular, it was found that no interlayer delamination was observed in Examples 1 to 4 and 6 to 10, which contained resin (A-2). Furthermore, as is clear from Reference Examples 1 to 2, although the average phase difference of resin (C) alone was remarkably high, Examples 1 to 13, which contained resin (B) and a compatibilized resin of resin (C), obtained a low average phase difference while maintaining higher transparency than Comparative Example 1, which contained only resin (A-1) and resin (B).
On the other hand, in Comparative Example 2, the transparency of the sample was too poor to measure the average phase difference. In Comparative Example 3, while sufficiently high transparency was obtained, similar to Examples 1 to 13, it became clear that a higher average phase difference was obtained than in Examples 1 to 13. In Comparative Example 4, while sufficiently high transparency and a low average phase difference were obtained, similar to Examples 1 to 13, it became clear that delamination was observed, resulting in a poor surface appearance.
In Reference Example 3, the L* value was 0.79, demonstrating that sufficient transparency can be achieved to produce jet blackness.

Claims (10)

A polycarbonate resin (A) containing a constituent unit derived from a dihydroxy compound represented by the following general formula (1),
A resin (B) having a constituent unit (b) derived from (meth)acrylic acid ester monomer components,
The present invention comprises a resin (C) having both acrylonitrile-derived structural units (c1) and aromatic vinyl monomer-derived structural units (c2) , and an elastomer (D) having a core-shell structure.
The aforementioned resin (B) and resin (C) are mutually compatible.
A thermoplastic resin composition in which the weight ratio of resin (B) to resin (C) is B:C = 99:1 to 1:99.
The thermoplastic resin composition according to claim 1 , wherein the resin (C) is an acrylonitrile styrene copolymer. The thermoplastic resin composition according to claim 1 or 2, wherein the elastomer (D) is obtained by graft copolymerizing copolymerizable monomer components with respect to a core layer as a shell layer, and this monomer component contains at least one monomer selected from (meth)acrylic acid and (meth)acrylic acid esters. The thermoplastic resin composition according to any one of claims 1 to 3, wherein when the total amount of the aforementioned resin (A), resin (B), resin (C), and elastomer (D) is 100 parts by weight, the total amount of resin (B) and resin (C) is 1 part by weight or more and 50 parts by weight or less, and the amount of elastomer (D) is 1 part by weight or more and 20 parts by weight or less. The thermoplastic resin composition according to any one of claims 1 to 4 , wherein the content ratio of resin (B) to resin (C) is B:C = 99:1 to 65:35 by weight. A polycarbonate resin (A) containing a constituent unit derived from a dihydroxy compound represented by the following general formula (1),
A resin (B) having a constituent unit (b) derived from (meth)acrylic acid ester monomer components,
The present invention comprises a resin (C1') consisting solely of structural units derived from acrylonitrile (c1) and structural units derived from aromatic vinyl monomers (c2), and an elastomer (D) having a core-shell structure.
A thermoplastic resin composition in which the weight ratio of resin (B) to resin (C1') is B:C1' = 99:1 to 1:99.
A molded article obtained by molding a thermoplastic resin composition according to any one of claims 1 to 6 . A polycarbonate resin (A) containing a constituent unit derived from a dihydroxy compound represented by the following general formula (1),
A resin (B) having a constituent unit (b) derived from a (meth)acrylic acid ester monomer component,
A resin (C) consisting of a resin (C1) having both constituent units derived from acrylonitrile (c1) and constituent units derived from aromatic vinyl monomers (c2),
Elastomer (D) consisting of a core-shell structure
A method for producing a thermoplastic resin composition, comprising the step of mixing resin (B) and resin (C), wherein the weight ratio of resin (B) to resin (C) is B:C = 99:1 to 1:99.
A method for producing a thermoplastic resin composition according to claim 8 , wherein the resin (C) is a resin (C1') consisting only of both constituent units (c1) derived from acrylonitrile and constituent units (c2) derived from aromatic vinyl monomers. A method for producing a thermoplastic resin composition according to claim 8 , wherein the resin (B) and resin (C) are mutually compatible.