Styrene resin composition and molded article

Abstract

To provide a styrenic resin composition that ensures excellent fluidity of the molten resin and gives a highly transparent molding therefrom.SOLUTION: A styrenic resin composition contains a copolymer (A) of a vinyl aromatic compound and a methacrylate, and a hydrogenated polystyrene resin (B), the styrenic resin composition having an MFR of 2.5 g / 10 min or more measured at 200°C, 49 N.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a styrenic resin composition and a molded article.

Background Art

[0002] Styrenic resins are excellent in properties such as transparency, rigidity, low water absorption, and dimensional stability, and are excellent in molding processability. Therefore, by various molding methods such as injection molding, extrusion molding, and blow molding, they are widely used as electrical products, various industrial materials, food packaging containers, sundries, etc. In addition, as a light guide plate, an acrylic resin typified by PMMA (polymethyl methacrylate) is used. However, since PMMA has high water absorption, there may be problems such as warpage in the molded article and dimensional changes. Therefore, it has been proposed to use a copolymer of an aromatic vinyl compound and a (meth)acrylate ester, which is excellent in the balance of heat resistance, transparency, and low water absorption, for example, an MS resin (methyl methacrylate-styrene resin) which is a copolymer of styrene and (meth)methyl acrylate.

[0003] As an example, Patent Document 1 discloses a styrene-(meth)acrylate copolymer resin comprising a styrenic monomer, a (meth)acrylate monomer, and a vinyl monomer copolymerizable with these monomers, wherein the styrenic monomer is 80 to 20% by mass, the (meth)acrylate monomer is 20 to 80% by mass, and the vinyl monomer copolymerizable with these monomers is 0 to 10% by mass, the weight average molecular weight (Mw) of the styrene-(meth)acrylate copolymer resin is 60,000 to 170,000, the residual monomer amount of the styrene-(meth)acrylate copolymer resin is 3000 ppm or less, and further the oligomer amount is 2% or less. An invention related to a light guide plate made of a styrene-(meth)acrylate copolymer resin is disclosed.

[0004] On the one hand, the MFR of the styrene-(meth)acrylic acid copolymer was as low as around 2 g / 10 min, for example, and there was room for improvement from the perspective of reducing the applied heat amount related to energy cost and resin deterioration. Patent Document 2 discloses, for example, a fluidity improver that is effective for a thermoplastic resin composition having an MFR of 10 or more, but it is not for a styrene-based resin composition with a low MFR, such as a copolymer of an aromatic vinyl compound and a (meth)acrylate ester containing an MS resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When applying a conventionally well-known fluidity improver to improve fluidity, there was a problem that the transparency required for the styrene-based resin was impaired due to the incompatibility between these fluidity improvers and the styrene-based resin composition and the refractive index mismatch between the two. Therefore, there has been a demand for a styrene-based resin composition capable of achieving both the fluidity of the molten resin and the transparency of the resin molded body.

[0007] The present invention has been made in view of such circumstances, and provides a styrene-based resin that is excellent in the fluidity of the molten resin, which has been difficult with conventional styrene-based resin compositions, and the molded body of the resin composition has high transparency.

Means for Solving the Problems

[0008] According to the present invention, a copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester, A styrene resin composition containing a hydrogenated polystyrene resin (B), wherein the MFR of the styrene resin composition measured at 200 ° C. and 49 N is 2.5 g / 10 min or more, is provided.

[0009] As a result of intensive studies by the present inventors to solve the above problems, a styrene resin composition containing a novel combination of a copolymer (A) of a vinyl aromatic compound and a (meth) acrylic acid ester and a hydrogenated polystyrene resin (B) It has been found that the fluidity of the styrene resin composition can be improved while maintaining the transparency of the resin molded body of the styrene resin composition, and the present invention has been completed.

[0010] Hereinafter, various embodiments of the present invention will be exemplified. The embodiments shown below can be combined with each other. It is possible. Preferably, the haze of a 2 mm thick molded body made of the styrene resin composition is 14.0% or less. Preferably, the weight average molecular weight of the styrene resin composition is 130,000 to 190,000. Preferably, the flexural modulus of the molded body made of the styrene resin composition is 3.0 GPa or more, and the flexural strength is 0.05 GPa or more. Preferably, the number average molecular weight of the hydrogenated polystyrene resin (B) is 500 to 4000, and the weight average molecular weight is 1000 to 5000. Preferably, the refractive index of the hydrogenated polystyrene resin (B) is 1.530 to 1.570.

[0011] According to another aspect of the present invention, there is provided a styrene resin composition containing a copolymer (A) of a vinyl aromatic compound and a (meth) acrylic acid ester and a hydrogenated polystyrene resin (B), wherein the styrene resin composition The haze of a 2 mm thick molded body made of is 14.0% or less. Further, according to still another aspect of the present invention, there is provided a molded body made of any of the above styrene resin compositions.

Effect of the invention

[0012] According to the present invention, by adjusting the fluidity of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate with a hydrogenated polystyrene resin (B), a styrenic resin composition having excellent fluidity and a molded article thereof having high transparency can be obtained.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be illustrated and the present invention will be described in detail. The present invention is not limited in any way by these descriptions. The various characteristic matters of the embodiments of the present invention shown below can be combined with each other. In this specification, the description of "XX to YY" means "XX or more and YY or less".

[0014] The styrenic resin composition according to the present invention contains a copolymer (A) of a vinyl aromatic compound and a (meth)acrylate and a hydrogenated polystyrene resin (B). Hereinafter, each component will be described in detail.

[0015] 1. Copolymer (A) of vinyl aromatic compound and (meth)acrylate The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate according to the present invention is obtained by copolymerizing a monomer mixture containing a vinyl aromatic compound and a (meth)acrylate. Therefore, the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate according to the present invention contains at least a monomer unit derived from a vinyl aromatic compound and a monomer unit derived from a (meth)acrylate.

[0016] The vinyl aromatic compound according to the present invention is a monocyclic or polycyclic aromatic vinyl monomer. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc. can be mentioned. Preferably, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, and more preferably styrene. These vinyl aromatic compounds may be used alone or in combination of two or more.

[0017] Examples of the (meth)acrylate according to the present invention include methacrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, etc. Preferably, methyl (meth)acrylate and n-butyl acrylate, and particularly preferably methyl (meth)acrylate. These (meth)acrylates may be used alone or in combination of two or more.

[0018] The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to an embodiment of the present invention may optionally contain monomer units derived from other monomers copolymerizable with these monomers. Examples of other monomers copolymerizable with these monomers include vinyl monomers, such as acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, N-phenylmaleimide, N-cyclohexylmaleimide, and the like.

[0019] The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to an embodiment of the present invention preferably contains 10 to 80% by mass of monomer units derived from the (meth)acrylate ester, more preferably 20 to 70% by mass, and even more preferably 25 to 65% by mass. The content of the monomer units derived from the (meth)acrylate ester in the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester can be, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80% by mass, and may be within the range between any two of the values exemplified herein. By setting the content of the monomer units derived from the (meth)acrylate ester to be not less than the above lower limit, it is possible to improve the MFR, which is an index of fluidity, while maintaining the haze of the material. In addition, mechanical properties such as flexural modulus and flexural strength can also be maintained within this content range.

[0020] The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to an embodiment of the present invention preferably contains 20 to 90% by mass of monomer units derived from the vinyl aromatic compound, more preferably 30 to 80% by mass, and even more preferably 35 to 75% by mass. The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to an embodiment of the present invention may contain 0 to 10% by mass of monomer units derived from other monomers copolymerizable with the vinyl aromatic compound and the (meth)acrylate ester, or may not contain monomer units derived from other monomers.

[0021] The number average molecular weight (Mn) of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to one embodiment of the present invention is preferably from 50,000 to 100,000, more preferably from 60,000 to 90,000. The weight average molecular weight (Mw) of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to one embodiment of the present invention is preferably from 130,000 to 200,000, more preferably from 140,000 to 190,000.

[0022] The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to one embodiment of the present invention preferably has a refractive index of 1.530 to 1.570. The refractive index can be, for example, 1.530, 1.535, 1.540, 1.545, 1.550, 1.555, 1.560, 1.565, 1.570, and may be within the range between any two of the values exemplified herein. The refractive index of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester can be measured, for example, using a molded article made of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester by measurement with an Abbe refractometer (JIS K 7142). The refractive index of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester can be controlled, for example, by adjusting the amount of the monomer unit derived from the vinyl aromatic compound (the amount of the monomer unit derived from the (meth)acrylate ester) in the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester. Specifically, when the content of the monomer unit derived from the vinyl aromatic compound is increased (when the amount of the monomer unit derived from the (meth)acrylate ester is decreased), the refractive index tends to increase.

[0023] The copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to one embodiment of the present invention preferably has an MFR (melt mass flow rate) measured at 200 °C and 49 N of 1.0 to 3.0 g / 10 min. The MFR of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester can be measured based on JIS K 7210. Further, the MFR of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester can be controlled, for example, by adjusting the molecular weight of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester.

[0024] There are no particular restrictions on the method for producing the copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester according to one embodiment of the present invention, and for example, polymerization methods such as emulsion polymerization method, suspension polymerization method, bulk polymerization method, solution polymerization method, etc. can be adopted.

[0025] 2. Hydrogenated polystyrene resin (B) The hydrogenated polystyrene resin (B) according to one embodiment of the present invention is obtained by hydrogenating a styrene resin to change at least a part of the aromatic ring into an alicyclic ring. Here, the styrene resin as the starting material of the hydrogenated polystyrene resin (B) is preferably obtained by addition polymerization of one or more styrene monomers. Examples of the styrene monomer include styrene, α-methylstyrene, β-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-phenylstyrene, and the like. The addition polymerization reaction can be carried out according to a known method. The addition polymerization can be carried out, for example, by solution polymerization using a living anionic polymerization catalyst, a method using a cationic polymerization catalyst, a method using a radical polymerization initiator, and the like.

[0026] The hydrogenated polystyrene resin (B) according to one embodiment of the present invention can be obtained by hydrogenating at least a part of the aromatic rings derived from styrenic monomers in the above styrene resin. The method of hydrogenation is a conventionally known method and is not particularly limited. For example, it can be carried out by bringing it into contact with a solution in which a styrene resin is dissolved in a solvent by blowing hydrogen in the presence of a known hydrogenation catalyst.

[0027] The hydrogenated polystyrene resin (B) according to one embodiment of the present invention preferably has a number average molecular weight of 500 to 4000, more preferably 1000 to 3000, and even more preferably 1500 to 2500. The hydrogenated polystyrene resin (B) according to one embodiment of the present invention preferably has a weight average molecular weight of 1000 to 5000, more preferably 2000 to 4000, and even more preferably 2000 to 3000. By setting it above the above lower limit, a molded article with sufficient strength can be obtained, and by setting it below the above upper limit, a hydrogenated polystyrene resin (B) excellent in fluidity improvement effect can be obtained.

[0028] The hydrogenated polystyrene resin (B) according to one embodiment of the present invention preferably has a refractive index of 1.530 to 1.570. The refractive index can be, for example, 1.530, 1.535, 1.540, 1.545, 1.550, 1.555, 1.560, 1.565, 1.570, and may be within the range between any two of the values exemplified here. The refractive index of the hydrogenated polystyrene resin (B) can be measured, for example, by measurement with an Abbe refractometer (JIS K 7142). Note that the refractive index of the hydrogenated polystyrene resin (B) can be adjusted, for example, by controlling the hydrogenation rate.

[0029] 3. Copolymer (A) of vinyl aromatic compound and (meth)acrylate The styrenic resin composition according to the present invention contains the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester described above, and the hydrogenated polystyrene resin (B) described above. In addition, the styrenic resin composition according to the present invention may use the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and the hydrogenated polystyrene resin (B) each alone, or may use a combination of two or more of each.

[0030] The styrenic resin composition according to the present invention has a novel combination of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and the hydrogenated polystyrene resin (B), and thus has excellent fluidity and high transparency in the molded article of the resin composition. Conventionally, styrenic resins containing a copolymer of a vinyl aromatic compound and a (meth)acrylate ester such as MS resin (methyl methacrylate / styrene resin) have extremely low fluidity, and there has been no fluidity improver suitable for low-fluidity styrenic resins. In addition, a styrenic resin composition containing a copolymer of a vinyl aromatic compound and a (meth)acrylate ester and a known fluidity improver do not have a compatible refractive index and have low compatibility, and the transparency of the resulting styrenic resin composition decreases when the two are combined. According to the present invention, by adding a hydrogenated polystyrene resin (B) having excellent refractive index compatibility and compatibility with respect to the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and having a fluidity improving effect suitable for a low-fluidity styrenic resin, a styrenic resin composition capable of achieving both the fluidity of the molten resin and the transparency of the resin molded article is provided.

[0031] The styrene resin composition according to one embodiment of the present invention has an MFR (melt mass flow rate) measured at 200 ° C. and 49 N of 2.5 g / 10 min or more, preferably 3.0 g / 10 min or more. The upper limit of the MFR is not particularly limited, and for example, it can be 20.0 g / 10 min or less, and in some cases, less than 6 g / 10 min. The MFR (melt mass flow rate) can be, for example, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 14.5, 16.0, 17.0, 18.0, 19.0, 20.0 g / 10 min, and may be within the range between any two of the values exemplified herein. The MFR of the styrene resin composition can be measured based on JIS K 7210. In addition, the MFR of the styrene resin composition can be controlled by adjusting the blending amount of the hydrogenated polystyrene resin (B) in the styrene resin composition, the molecular weight of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate, the content of the (meth)acrylate monomer unit in the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate, the molecular weight of the hydrogenated polystyrene resin (B), etc.

[0032] The styrene resin composition according to one embodiment of the present invention preferably has a haze of 14.0% or less, more preferably 10.0% or less, even more preferably 5.0% or less, and particularly more preferably 2.0% or less for a molded body having a thickness of 2 mm made of the styrene resin composition. The haze can be, for example, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0%, and may be within the range between any two of the values exemplified herein. Note that the haze can be measured using a haze meter based on JIS K 7105 for a test piece (thickness 2 mm, dimensions 40 mm × 40 mm) prepared by injection molding styrene resin composition pellets using an injection molding machine at a cylinder temperature of 175 to 215 ° C. and a mold temperature of 45 ° C.

[0033] According to the present invention, a styrenic resin composition excellent in transparency can be obtained by adjusting the fluidity of a copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester with a hydrogenated polystyrene resin (B). The haze of a molded article of the styrenic resin composition can be controlled by adjusting the blending amount of the hydrogenated polystyrene resin (B) in the styrenic resin composition, the molecular weight of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester, the content of the (meth)acrylic acid ester monomer unit in the copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester, the molecular weight of the hydrogenated polystyrene resin (B), etc. In particular, by making the refractive indices of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester and the hydrogenated polystyrene resin (B) closer to each other, the haze value can be made lower.

[0034] In the styrenic resin composition according to one embodiment of the present invention, the difference between the refractive index of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester and the refractive index of the hydrogenated polystyrene resin (B) is preferably within 0.030, more preferably within 0.020, and even more preferably within 0.010. By making the refractive indices of the copolymer (A) of a vinyl aromatic compound and a (meth)acrylic acid ester contained in the styrenic resin composition and the hydrogenated polystyrene resin (B) closer to each other, the transparency of the obtained styrenic resin composition can be further improved.

[0035] When the total amount of the styrene resin composition according to the present invention is 100% by mass, it preferably contains 0.1 to 40% by mass of the hydrogenated polystyrene resin (B), more preferably 0.5 to 30% by mass, and even more preferably 1 to 25% by mass. The content of the hydrogenated polystyrene resin (B) can be, for example, 0.1, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0% by mass, and it may also be within the range between any two of the values exemplified here. By setting it within the above numerical range, a styrene resin composition excellent in the balance between the fluidity of the molten resin and the transparency of the resin molded body can be obtained.

[0036] The styrene resin composition according to the present invention contains the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester described above, and the hydrogenated polystyrene resin (B) described above, and may contain other components as long as the effects of the present invention are not inhibited. Examples of other components include fillers, light stabilizers, antioxidants, heat stabilizers, flame retardants, ultraviolet absorbers, dyes and pigments, fluorescent brighteners, anti-dripping agents, antistatic agents, anti-fogging agents, lubricants, antiblocking agents, fluidity improvers, plasticizers, dispersants, antibacterial agents, and the like. These components may be used alone or in combination of two or more. When these components are blended, it is preferable to adjust each of the other components within the range of 0 to 10% by mass with the total amount of the styrene resin composition being 100% by mass. The styrene resin composition according to the present invention may also consist only of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and the hydrogenated polystyrene resin (B).

[0037] The styrene resin composition according to the present invention may contain a known fluidity improver as long as the effects of the present invention are not inhibited. Examples of the known fluidity improver include higher fatty acids and their salts such as stearic acid, zinc stearate, calcium stearate, and magnesium stearate, and ethylene bisstearylamide, polyethylene wax, and the like. When the styrene resin composition according to the present invention contains a fluidity improver other than the hydrogenated polystyrene resin (B) as described above, the content thereof is preferably less than 1% by mass, and more preferably less than 0.5% by mass. The styrene resin composition according to the present invention can be one that does not contain a fluidity improver other than the hydrogenated polystyrene resin (B).

[0038] The styrene resin composition according to one embodiment of the present invention preferably has a number average molecular weight of 60,000 to 110,000, and more preferably 70,000 to 100,000. The hydrogenated polystyrene resin (B) according to one embodiment of the present invention preferably has a weight average molecular weight of 130,000 to 190,000, and more preferably 140,000 to 180,000. By setting the numerical range as described above, a styrene resin composition having an excellent balance between fluidity and strength can be obtained. The molecular weight of the styrene resin composition can be controlled by adjusting the blending amount of the hydrogenated polystyrene resin (B) contained in the styrene resin composition, and the molecular weights of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and the hydrogenated polystyrene resin (B).

[0039] The styrene resin composition according to one embodiment of the present invention preferably has a flexural modulus of 3.0 GPa or more, more preferably 3.1 GPa or more, and even more preferably 3.2 GPa or more for a molded article made of the styrene resin composition. The flexural modulus can be evaluated based on JIS K 7171. Further, in the styrene resin composition according to an embodiment of the present invention, it is preferable that the flexural strength of the molded body made of the styrene resin composition is 0.05 GPa or more. The flexural strength can be evaluated based on JIS K 7171. The flexural modulus and flexural strength of the styrene resin composition can be controlled by adjusting the molecular weight of the styrene resin composition, the blending amount of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate, the content of the (meth)acrylate monomer unit, and the molecular weight of the hydrogenated polystyrene resin (B).

[0040] 3. Method for producing styrene resin composition The styrene resin composition of the present invention can be produced by adding a hydrogenated polystyrene resin (B) to a copolymer (A) of a vinyl aromatic compound and a (meth)acrylate. Examples of the addition method include a method of adding and mixing in the polymerization step, devolatilization step, and granulation step of the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate, and a method of adding and mixing with an extruder or an injection molding machine during the molding process, etc., and it is not particularly limited.

[0041] 4. Molded body containing styrene resin composition The molded body according to an embodiment of the present invention contains the above-mentioned styrene resin composition. The styrene resin composition of the present invention can be made into a molded product by a molding method according to the purpose, such as injection molding, extrusion molding, compression molding, blow molding, etc., and its shape is not limited. For example, if it is a plate-shaped molded product, it can be processed into a light guide plate or the like.

Examples

[0042] The present invention will be further specifically described by way of examples, but the present invention is not limited thereto in any way.

[0043] <Example> As the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate, the following methyl methacrylate·styrene resin was prepared. Methacrylate-styrene resin (A-1): manufactured by Toyo Styrene Co., Ltd., MFR 2.8 g / 10 min, refractive index 1.565, Methacrylate-styrene resin (A-2): manufactured by Toyo Styrene Co., Ltd., MFR 1.8 g / 10 min, refractive index 1.551, Methacrylate-styrene resin (A-3): manufactured by Toyo Styrene Co., Ltd., MFR 1.0 g / 10 min, refractive index 1.535

[0044] Also, the following were prepared as hydrogenated polystyrene resins (B). Hydrogenated polystyrene resin (B-1): number average molecular weight 1.8×10 3 , weight average molecular weight 2.7×10 3 , refractive index 1.565 Hydrogenated polystyrene resin (B-2): number average molecular weight 1.8×10 3 , weight average molecular weight 2.7×10 3 , refractive index 1.551 Hydrogenated polystyrene resin (B-3): number average molecular weight 1.8×10 3 , weight average molecular weight 2.7×10 3 , refractive index 1.543

[0045] Also, the following were prepared as other commercially available additives. · Zinc stearate · Polyethylene wax

[0046] With the formulations shown in Table 1 and Table 2, methacrylate-styrene resins (A-1) to (A-3), hydrogenated polystyrene resins (B-1) to (B-3), and other additives were melt-kneaded using a twin-screw kneading extruder with a screw diameter of 26 mm at a cylinder temperature of 230°C, a screw rotation speed of 300 rpm, and a discharge rate of 25 to 30 kg per hour to obtain pellets.

[0047] The following evaluations were performed on the obtained styrene resin composition. The results are shown in Table 1 and Table 2.

[0048] <Weight average molecular weight (Mw) and number average molecular weight (Mn)> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured under the following conditions using gel permeation chromatography (GPC). GPC model: Shodex GPC-101 manufactured by Showa Denko K.K. Column: PLgel 10μm MIXED-B manufactured by Polymer Laboratories Mobile phase: Tetrahydrofuran Sample concentration: 0.2 mass% Temperature: Oven 40°C, injection port 35°C, detector 35°C Detector: Differential refractometer The molecular weight was calculated as the molecular weight at each elution time from the elution curve of monodisperse polystyrene and was calculated as the molecular weight in terms of polystyrene.

[0049] <Measurement of Haze> Pellets of the styrene resin composition were injection-molded at a cylinder temperature of 175 to 215°C and a mold temperature of 45°C using an injection molding machine (IS130FII-3A) manufactured by Toshiba Machine Co., Ltd. Using the obtained test pieces (thickness 2 mm, dimensions 40 mm × 40 mm), Haze (unit: %) was measured in accordance with JIS K 7105 using a haze meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.).

[0050] <Measurement of MFR> The MFR (melt mass flow rate) of the styrene resin composition was measured in accordance with JIS K 7210 under the conditions of 200°C and a load of 49 N.

[0051] <Flexural strength> Pellets of the styrene resin composition were injection-molded at a cylinder temperature of 175 to 215°C and a mold temperature of 45°C using an injection molding machine (IS130FII-3A) manufactured by Toshiba Machine Co., Ltd. Using the obtained test pieces, the flexural strength (MPa) was evaluated in accordance with JIS K 7171 using a ventograph manufactured by Toyo Seiki Seisaku-sho, Ltd.

[0052] <Flexural modulus> Pellets of the styrene resin composition were injection-molded using an injection molding machine (IS130FII-3A) manufactured by Toshiba Machine Co., Ltd. at a cylinder temperature of 175 to 215°C and a mold temperature of 45°C. Using the obtained test pieces, the flexural modulus (MPa) was evaluated in accordance with JIS K 7171 using a ventograph manufactured by Toyo Seiki Co., Ltd.

[0053] [Table 1]

[0054] [Table 2]

Claims

1. A styrenic resin composition comprising a copolymer (A) of a vinyl aromatic compound and a (meth)acrylate, and a hydrogenated polystyrene resin (B), wherein the hydrogenated polystyrene resin (B) is obtained by hydrogenating a styrene resin obtained by addition polymerization of one or more styrenic monomers, the MFR of the styrenic resin composition measured at 200 °C and 49 N is 2.5 g / 10 min or more, the styrenic resin composition contains 0.1 to 40% by mass of the hydrogenated polystyrene resin (B) based on 100% by mass of the entire styrenic resin composition, the styrenic resin composition contains 0 to 10% by mass of other components other than the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate and the hydrogenated polystyrene resin (B) based on 100% by mass of the entire styrenic resin composition, A styrenic resin composition.

2. The styrenic resin composition according to claim 1, wherein the haze of a molded article having a thickness of 2 mm made of the styrenic resin composition is 14.0% or less.

3. The styrenic resin composition according to claim 1 or 2, wherein the weight average molecular weight of the styrenic resin composition is 130,000 to 190,000.

4. The styrenic resin composition according to any one of claims 1 to 3, wherein the flexural modulus of a molded article made of the styrenic resin composition is 3.0 GPa or more and the flexural strength is 0.05 GPa or more.

5. The styrenic resin composition according to any one of claims 1 to 4, wherein the number average molecular weight of the hydrogenated polystyrene resin (B) is 500 to 4000 and the weight average molecular weight is 1000 to 5000.

6. The styrenic resin composition according to any one of claims 1 to 5, wherein the refractive index of the hydrogenated polystyrene resin (B) is 1.530 to 1.

570.

7. A copolymer (A) of a vinyl aromatic compound and a (meth)acrylate ester, and A styrenic resin composition containing a hydrogenated polystyrene resin (B), wherein the hydrogenated polystyrene resin (B) is obtained by hydrogenating a polystyrene resin obtained by addition polymerization of one or more styrenic monomers, the haze of a molded article having a thickness of 2 mm made of the styrenic resin composition is 14.0% or less, when the total amount of the styrenic resin composition is 100% by mass, the hydrogenated polystyrene resin (B) is contained in an amount of 0.1 to 40% by mass, when the total amount of the styrenic resin composition is 100% by mass, the content of other components other than the copolymer (A) of the vinyl aromatic compound and the (meth)acrylate ester and the hydrogenated polystyrene resin (B) is 0 to 10% by mass, A styrenic resin composition.

8. A molded article made of the styrenic resin composition according to any one of claims 1 to 7.

Images