阅读说明：本技术 热塑性树脂组合物、成型体、和车辆用部件 (Thermoplastic resin composition, molded article, and vehicle member ) 是由 杨井寿美 饰西佳史 兼森纮一 于 2018-07-10 设计创作，主要内容包括：本发明提供一种耐热性、透明性、成型后的外观和耐候性优异且抑制了成型加工中的着色的热塑性树脂组合物。本发明的热塑性树脂组合物为包含共聚物(P1)和下述通式(1)所表示的抗氧化剂(O)的热塑性树脂组合物,相对于所述热塑性树脂组合物的总质量,所述热塑性树脂组合物含有80质量％以上的所述共聚物(P1),且所述共聚物(P1)包含80mol％以上的源自(甲基)丙烯酸甲酯(a)的重复单元(A)、2mol％以上且7mol％以下的源自(甲基)丙烯酸(b)的重复单元(B)、和0.001mol％以上且0.15mol％以下的具有戊二酸酐结构的重复单元(C)。[式(1)中,R<Sup>1</Sup>和R<Sup>1’</Sup>各自独立地表示在苯基上的任意位置取代的单个或多个碳原子数1～8的烷基。]<Image he="119" wi="700" file="DDA0002362746560000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention provides a thermoplastic resin composition which is excellent in heat resistance, transparency, appearance after molding and weather resistance and is suppressed in coloring during molding. The thermoplastic resin composition of the present invention is a thermoplastic resin composition comprising a copolymer (P1) and an antioxidant (O) represented by the following general formula (1), wherein the thermoplastic resin composition contains the copolymer (P1) in an amount of 80 mass% or more based on the total mass of the thermoplastic resin composition, and the copolymer (P1) containsContains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.001 mol% or more and 0.15 mol% or less of a repeating unit (C) having a glutaric anhydride structure. [ in the formula (1), R 1 And R 1' Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.])

1. A thermoplastic resin composition comprising a copolymer (P1) and an antioxidant (O) represented by the following general formula (1),

the thermoplastic resin composition contains 80 mass% or more of the copolymer (P1) relative to the total mass of the thermoplastic resin composition, and

the copolymer (P1) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.001 mol% or more and 0.15 mol% or less of a repeating unit (C) having a glutaric anhydride structure,

[ solution 1]

In the formula (1), R¹And R^1'Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.

2. The thermoplastic resin composition according to claim 1, wherein the antioxidant (O) is represented by the following general formula (2),

[ solution 2]

In the formula (2), R²And R^2'Each independently represents an alkyl group having 1 to 8 carbon atoms.

3. The thermoplastic resin composition according to claim 1 or 2, which contains the antioxidant (O) in an amount of 0.01 to 0.18 mass% based on the total mass of the thermoplastic resin composition.

4. The thermoplastic resin composition according to any one of claims 1 to 3, which contains the phenolic compound represented by the following general formula (3) in an amount of 0.001 to 0.4% by mass based on the total mass of the thermoplastic resin composition,

[ solution 3]

In the formula (3), R³Represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at any position on the phenyl group.

5. The thermoplastic resin composition according to claim 4, wherein the antioxidant (O) is a compound represented by the general formula (2),

the phenolic compound is a compound represented by the following general formula (4),

[ solution 4]

In the formula (4), R⁴Represents an alkyl group having 1 to 8 carbon atoms.

6. The thermoplastic resin composition according to any one of claims 1 to 5, which contains the antioxidant (O) in an amount of 0.02 mass% or more and 0.14 mass% or less with respect to the total mass of the thermoplastic resin composition,

the copolymer (P1) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.005 mol% or more and 0.02 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

7. The thermoplastic resin composition according to any one of claims 1 to 5, which contains the antioxidant (O) in an amount of 0.03 to 0.13 mass% based on the total mass of the thermoplastic resin composition,

the copolymer (P1) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 4 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.0075 mol% or more and 0.015 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

8. The thermoplastic resin composition according to any one of claims 1 to 7, wherein the total content of the unreacted methyl (meth) acrylate (a) and the unreacted (meth) acrylic acid (b) contained in the thermoplastic resin composition is 0.5% by mass or less based on the total mass of the thermoplastic resin composition.

9. A molded article comprising the thermoplastic resin composition according to any one of claims 1 to 8.

10. A molded article comprising a copolymer (P2) and an antioxidant (O) represented by the following general formula (5),

the molded body contains 80 mass% or more of the copolymer (P2) relative to the total mass of the molded body, and

the copolymer (P2) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.01 mol% or more and 2 mol% or less of a repeating unit (C) having a glutaric anhydride structure,

[ solution 5]

In the formula (5), R⁵And R^5’Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.

11. The thermoplastic resin composition according to claim 10, wherein said antioxidant (O) is represented by the following general formula (6),

[ solution 6]

In the formula (6), R⁶And R^6’Each independently represents an alkyl group having 1 to 8 carbon atoms.

12. The molded body according to claim 10 or 11, wherein the antioxidant (O) is contained in an amount of 0.001 to 0.12 mass% based on the total mass of the molded body.

13. The molded article according to any one of claims 10 to 12, which contains the phenolic compound represented by the following general formula (7) in an amount of 0.001 to 1.0 mass% based on the total mass of the molded article,

[ solution 7]

In the formula (7), R⁷Represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at any position on the phenyl group.

14. The molded article according to claim 13, wherein the phenolic compound is a compound represented by the following general formula (8),

[ solution 8]

In the formula (8), R⁸Represents an alkyl group having 1 to 8 carbon atoms.

15. The molded body according to any one of claims 10 to 14, which contains an antioxidant (O) represented by the general formula (5) in an amount of 0.002 mass% or more and 0.03 mass% or less based on the total mass of the molded body,

the copolymer (P2) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.02 mol% or more and 1.2 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

16. The molded body according to any one of claims 10 to 14, which contains the antioxidant (O) in an amount of 0.01 to 0.025 mass% based on the total mass of the molded body,

the copolymer (P2) contains 80 mol% or more of a repeating unit (A) derived from methyl (meth) acrylate (a), 2 mol% or more and 3.5 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.03 mol% or more and 0.6 mol% or less of a repeating unit having a glutaric anhydride structure.

17. A part for a vehicle, comprising the molded article according to any one of claims 9 to 16.

Technical Field

The present invention relates to a thermoplastic resin composition which is excellent in heat resistance, transparency, appearance after molding and weather resistance and in which coloring during molding is suppressed; a molded body comprising the thermoplastic resin composition; and a vehicle member comprising the molded article.

The present application claims priority based on japanese patent application No. 2017-138114, which was filed in japan on 14.7.2017 and japanese patent application No. 2018-104326, which was filed in japan on 31.5.2018, and the contents of which are incorporated herein by reference.

Background

Because of their excellent transparency and dimensional stability, (meth) acrylic resins are widely used in various fields such as optical materials, vehicle parts such as automobiles, lighting materials, and building materials.

In recent years, there has been a growing demand for a material which is suitable for use in a lamp cover and a vehicle member, has excellent transparency and dimensional stability, and has optical properties as a vehicle member (patent document 1).

In recent years, higher performance has been demanded for molded articles of (meth) acrylic resins in accordance with the thinning and precision of parts. In particular, for vehicle parts such as tail lamp covers and head lamp covers, (meth) acrylic resins having excellent heat resistance are required because of requirements such as an increase in the size of the lamp, an increase in the amount of heat generated due to an increase in illuminance, a reduction in the thickness of the lamp cover due to a reduction in cost, and the like, and requirements for being able to be installed at a position where the temperature rapidly rises under direct sunlight.

Further, the number of cases in which the vehicle member is disposed in a position where it is easily exposed to direct sunlight is increased, and a (meth) acrylic resin having excellent weather resistance is required.

In addition, the vehicle parts are required to be transparent and have a low feeling of presence from the viewpoint of design. That is, a (meth) acrylic resin which is excellent in transparency and is suppressed in coloring during molding is required.

Melt molding of (meth) acrylic resins using a large extruder having a long residence time is increasing, and further, since (meth) acrylic resins having improved heat resistance need to be molded at a higher temperature than conventional ones, it is required that the appearance after molding is not impaired by thermal decomposition of the (meth) acrylic resins. That is, a (meth) acrylic resin having excellent appearance after molding is required.

As a method for improving the heat resistance of a (meth) acrylic resin, for example, patent document 1 and patent document 2 propose a copolymer having a methyl methacrylate unit, a methacrylic acid unit, and a glutaric anhydride unit.

Patent document 3 proposes a thermoplastic resin composition containing a heat-resistant acrylic copolymer, a phosphite compound and a hindered phenol compound.

Patent document 4 proposes a thermoplastic resin composition having a heat-resistant acrylic copolymer and a white pigment.

Disclosure of Invention

Problems to be solved by the invention

However, the copolymer proposed in patent document 1 has a large content of glutaric anhydride units, and is insufficient in weather resistance, and further is colored yellow to cause poor transparency. In addition, the molded appearance may be impaired by thermal decomposition of the copolymer.

The copolymer proposed in patent document 2 has a small content of glutaric anhydride units to suppress yellow coloration, but the effect is not sufficient. In addition, the weather resistance is insufficient.

The thermoplastic resin composition proposed in patent document 3 is inhibited from coloring yellow by a stabilizer, but the content of glutaric acid anhydride units is large, the weather resistance is insufficient, and further, the composition is colored yellow to cause poor transparency. In addition, the molded appearance may be impaired by thermal decomposition of the copolymer.

The thermoplastic resin composition proposed in patent document 4 has improved yellow coloration by a white pigment, but is white and therefore is limited to use in non-transparent applications such as a reflector. I.e., no transparency.

The present invention aims to solve these problems.

That is, an object of the present invention is to provide a thermoplastic resin composition which is excellent in heat resistance, transparency, appearance after molding and weather resistance and in which coloring during molding is suppressed, a molded article comprising the thermoplastic resin composition, and a vehicle member comprising the molded article.

Means for solving the problems

The present inventors have made extensive studies to solve the above problems, and as a result, the present invention has been completed.

The present invention has the following aspects.

[1] A thermoplastic resin composition comprising a copolymer (P1) and an antioxidant (O) represented by the following general formula (1),

the thermoplastic resin composition contains the copolymer (P1) in an amount of 80 mass% or more based on the total mass of the thermoplastic resin composition, and

the copolymer (P1) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.001 mol% or more and 0.15 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

[ solution 1]

[ in the formula (1), R¹And R^1’Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.]

[2] The thermoplastic resin composition according to [1], wherein the antioxidant (O) is represented by the following general formula (2).

[ solution 2]

[ in the formula (2), R²And R^2’Each independently represents an alkyl group having 1 to 8 carbon atoms.]

[3] The thermoplastic resin composition according to [1] or [2], wherein the antioxidant (O) is contained in an amount of 0.01 to 0.18 mass% based on the total mass of the thermoplastic resin composition.

[4] The thermoplastic resin composition according to any one of [1] to [3], wherein the phenolic compound represented by the following general formula (3) is contained in an amount of 0.001 to 0.4 mass% based on the total mass of the thermoplastic resin composition.

[ solution 3]

[ in the formula (3), R³Represents a single or multiple C1-8 alkyl group substituted at any position on the phenyl group]

[5] The thermoplastic resin composition according to [4], wherein the antioxidant (O) is a compound represented by the general formula (2),

the phenolic compound is a compound represented by the following general formula (4).

[ solution 4]

[ in the formula (4), R⁴Represents an alkyl group having 1 to 8 carbon atoms]

[6] The thermoplastic resin composition according to any one of [1] to [5], which contains the antioxidant (O) in an amount of 0.02 to 0.14 mass% based on the total mass of the thermoplastic resin composition,

the copolymer (P1) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.005 mol% or more and 0.02 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

[7] The thermoplastic resin composition according to any one of [1] to [5], which contains the antioxidant (O) in an amount of 0.03 to 0.13 mass% based on the total mass of the thermoplastic resin composition,

the copolymer (P1) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 4 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.0075 mol% or more and 0.015 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

[8] The thermoplastic resin composition according to any one of [1] to [7], wherein the total content of the unreacted methyl (meth) acrylate (a) and the unreacted (meth) acrylic acid (b) contained in the thermoplastic resin composition is 0.5% by mass or less based on the total mass of the thermoplastic resin composition.

[9] A molded article comprising the thermoplastic resin composition according to any one of [1] to [8 ].

[10] A molded article comprising a copolymer (P2) and an antioxidant (O) represented by the following general formula (5),

the molded article contains the copolymer (P2) in an amount of 80 mass% or more based on the total mass of the molded article, and

the copolymer (P2) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.01 mol% or more and 2 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

[ solution 5]

[ in the formula (5), R⁵And R^5’Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.]

[11] The thermoplastic resin composition according to [10], wherein the antioxidant (O) is represented by the following general formula (6).

[ solution 6]

[ in the formula (6), R⁶And R^6’Each independently represents an alkyl group having 1 to 8 carbon atoms.]

[12] The molded article according to [10] or [11], wherein the antioxidant (O) is contained in an amount of 0.001 to 0.12 mass% based on the total mass of the molded article.

[13] The molded article according to any one of [10] to [12], wherein the molded article contains the phenolic compound represented by the following general formula (7) in an amount of 0.001 to 1.0 mass% based on the total mass of the molded article.

[ solution 7]

[ in the formula (7), R⁷Represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at any position on the phenyl group.]

[14] The molded article according to [13], wherein the phenolic compound is a compound represented by the following general formula (8).

[ solution 8]

[ in the formula (8), R⁸Represents an alkyl group having 1 to 8 carbon atoms.]

[15] The molded article according to any one of [10] to [14], which contains the antioxidant (O) represented by the general formula (5) in an amount of 0.002 mass% or more and 0.03 mass% or less based on the total mass of the molded article,

the copolymer (P2) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 7 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.02 mol% or more and 1.2 mol% or less of a repeating unit (C) having a glutaric anhydride structure.

[16] The molded article according to any one of [10] to [14], which contains the antioxidant (O) in an amount of 0.01 to 0.025 mass% based on the total mass of the molded article,

the copolymer (P2) contains 80 mol% or more of a repeating unit (a) derived from methyl (meth) acrylate (a), 2 mol% or more and 3.5 mol% or less of a repeating unit (B) derived from (meth) acrylic acid (B), and 0.03 mol% or more and 0.6 mol% or less of a repeating unit having a glutaric anhydride structure.

[17] A part for a vehicle, comprising the molded article according to any one of [9] to [16 ].

Effects of the invention

The thermoplastic resin composition of the present invention is excellent in heat resistance, transparency, appearance after molding and weather resistance, and is suppressed in coloring during molding.

The molded article of the present invention is excellent in heat resistance, transparency, appearance, and weather resistance because it contains the thermoplastic resin composition of the present invention.

The vehicle member of the present invention is excellent in heat resistance, transparency, appearance, and weather resistance because it contains the molded article of the present invention.

The thermoplastic resin composition and the molded article of the present invention are suitable for use in automotive parts such as tail lamp covers and headlight covers.

Detailed Description

The present invention will be described in detail below. In the present invention, "(meth) acrylate" and "(meth) acrylic acid" mean at least one selected from "acrylate" and "methacrylate" and at least one selected from "acrylic acid" and "methacrylic acid", respectively.

Further, "monomer" means an unpolymerized compound, and "repeating unit" means a unit derived from the above-mentioned monomer formed by polymerization of the monomer. The "repeating unit" may be a unit directly formed by polymerization, or may be a unit in which a part of the above-mentioned unit is converted into another structure by treating a polymer.

As described later, the repeating unit (a) derived from methyl (meth) acrylate (a) in the polymer does not include the repeating unit (C) having a glutaric anhydride structure. In addition, the repeating unit (B) derived from (meth) acrylic acid (B) in the polymer does not include the repeating unit (C) having a glutaric anhydride structure.

"mass%" means the content of a specific component contained in 100 mass% of the total amount.

Unless otherwise specified, the numerical range expressed by the term "to" in the present specification means a range including the numerical values described before and after the term "to" as a lower limit value and an upper limit value, and the terms "a" to "mean" a is not less than B.

< thermoplastic resin composition >

The thermoplastic resin composition of the present invention is a resin composition containing the copolymer (P1) described later and the antioxidant (O) described later.

The thermoplastic resin composition of the present invention contains the copolymer (P1) in an amount of 80 mass% or more based on the total mass of the thermoplastic resin composition.

When the copolymer (P1) is contained in an amount of 80% by mass or more, a molded article obtained by molding the thermoplastic resin composition of the present invention is excellent in transparency, heat resistance, molding coloration, molding appearance, and weather resistance. The thermoplastic resin composition of the present invention more preferably contains the copolymer (P1) in an amount of 90 mass% or more based on the total mass of the thermoplastic resin composition.

The antioxidant (O) contained in the thermoplastic resin composition of the present invention is consumed for preventing thermal decomposition and oxidative deterioration of the copolymer (P1) when the thermoplastic resin composition is heated to a molten state by an extruder, an injection molding machine, or the like to produce a molded article.

The lower limit of the content of the antioxidant (O) in the thermoplastic resin composition of the present invention is not particularly limited, but is preferably 0.01% by mass, more preferably 0.02% by mass, and even more preferably 0.03% by mass, based on the total mass of the thermoplastic resin composition, from the viewpoint of suppressing the molding coloration of a molded article obtained by molding the thermoplastic resin composition of the present invention and improving the molding appearance. The upper limit of the content of the antioxidant (O) in the thermoplastic resin composition of the present invention is not particularly limited, but is preferably 0.18 mass%, more preferably 0.14 mass%, and still more preferably 0.13 mass% based on the total mass of the thermoplastic resin composition, from the viewpoint that a molded article having a good appearance can be obtained without causing mold fouling, die fouling, or the like at the time of injection molding or extrusion molding, and further the weather resistance of the molded article is improved.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the antioxidant (O) in the thermoplastic resin composition of the present invention is preferably 0.01% by mass or more and 0.18% by mass or less, more preferably 0.02% by mass or more and 0.14% by mass or less, and further preferably 0.03% by mass or more and 0.13% by mass or less, based on the total mass of the thermoplastic resin composition.

< shaped body >

The first embodiment of the molded article of the present invention is a molded article obtained by molding the thermoplastic resin composition of the present invention.

The second embodiment of the molded article of the present invention is a molded article comprising the copolymer (P2) described later and the antioxidant (O) described later.

The second form of the molded article of the present invention contains 80% by mass or more of the copolymer (P2) based on the total mass of the molded article.

When 80% by mass or more of the copolymer (P2) is contained, the molded article is excellent in transparency, heat resistance, molding coloration, molding appearance, and weather resistance. The second embodiment of the molded article of the present invention more preferably contains 90% by mass or more of the copolymer (P2) based on the total mass of the molded article.

The lower limit of the content of the antioxidant (O) in the second embodiment of the molded article of the present invention is not particularly limited, but is preferably 0.001 mass%, more preferably 0.002 mass%, and still more preferably 0.01 mass% based on the total mass of the molded article, from the viewpoint of suppressing molding coloration of the molded article and improving the molded appearance. The upper limit of the content of the antioxidant (O) in the second embodiment of the molded article of the present invention is not particularly limited, but is preferably 0.12% by mass, more preferably 0.03% by mass, and still more preferably 0.025% by mass, based on the total mass of the molded article, from the viewpoint of improving the molded appearance and weather resistance of the molded article.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the antioxidant (O) in the second embodiment of the molded article of the present invention is preferably 0.001 mass% or more and 0.12 mass% or less, more preferably 0.002 mass% or more and 0.03 mass% or less, and further preferably 0.01 mass% or more and 0.025 mass% or less, based on the total mass of the molded article.

< copolymer (P1) >

The copolymer (P1) is one of the components of the thermoplastic resin composition of the present invention.

When the thermoplastic resin composition of the present invention contains the copolymer (P1), the molded article has excellent heat resistance.

The copolymer (P1) of the present invention comprises a repeating unit (a) derived from methyl (meth) acrylate (a) (hereinafter, simply referred to as "unit (a)"), a repeating unit (B) derived from (meth) acrylic acid (B) (hereinafter, simply referred to as "unit (B)"), and a repeating unit (C) having a glutaric anhydride structure (hereinafter, simply referred to as "unit (C)").

Details of the methyl (meth) acrylate (a) and the (meth) acrylic acid (b) will be described later.

The unit (C) in the copolymer (P1) is a structural unit represented by the following chemical structural formula. The unit (C) in the copolymer (P2) described later is also a structural unit having the same chemical structural formula.

[ solution 9]

[ in the formula, R^AAnd R^BEach independently represents a hydrogen atom or a methyl group.]

As a conventional technique for imparting heat resistance to a (meth) acrylic resin, for example, a method of containing at least one selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide-based structural unit, and a lactone ring-based unit as described in japanese patent application laid-open No. 2017-132981 or the like is known, but there is a problem that coloring is easy because a nitrogen-based compound is used as a raw material; it is not suitable for outdoor use because it is susceptible to hydrolysis.

The thermoplastic resin composition of the present invention can improve heat resistance without being affected by coloring, hydrolysis, and the like by the copolymer (P1) containing the unit (C).

From the viewpoint of not impairing the original performance of the acrylic resin, such as excellent transparency and processability and mechanical properties of a molded article obtained by molding the thermoplastic resin composition of the present invention, the lower limit of the content of the unit (a) in the copolymer (P1) is 80 mol%, more preferably 90 mol%, relative to the total mole number of the repeating units contained in the copolymer (P1). The upper limit value of the content of the unit (a) in the copolymer (P1) is 97.999 mol%, and from the viewpoint of excellent heat resistance of a molded article obtained by molding the thermoplastic resin composition of the present invention, the upper limit value is preferably 97 mol%, and more preferably 96 mol%.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (a) in the copolymer (P1) is preferably 80 mol% or more and 97.999 mol% or less, more preferably 80 mol% or more and 97 mol% or less, and still more preferably 90 mol% or more and 96 mol% or less, based on the total number of moles of the repeating units contained in the copolymer (P1).

As described later, the repeating unit (C) having a glutaric anhydride structure is a unit which is constructed by a cyclization reaction of a methoxycarbonyl group derived from the methyl (meth) acrylate (a) and a carboxyl group derived from the (meth) acrylic acid (b) adjacent to the methoxycarbonyl group in a copolymer obtained by copolymerizing the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), and is derived from the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), but the unit (C) is not contained in the unit (a).

From the viewpoint of excellent heat resistance and mechanical properties of a molded article obtained by molding the thermoplastic resin composition of the present invention, the lower limit of the content of the unit (B) in the copolymer (P1) is 2 mol%, more preferably 2.5 mol%, based on the total mole number of the repeating units contained in the copolymer (P1). From the viewpoint of not impairing the original performance of the acrylic resin, such as molded appearance, low water absorption, and excellent moldability of a molded article obtained by molding the thermoplastic resin composition of the present invention, the upper limit of the content of the unit (B) in the copolymer (P1) is 7 mol%, and more preferably 3.5 mol%.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (B) in the copolymer (P1) is 2 mol% or more and 7 mol% or less, preferably 2.5 mol% or more and 6 mol% or less, based on the total mole number of the repeating units contained in the copolymer (P1).

As described later, the repeating unit (C) having a glutaric anhydride structure is a unit which is constructed by a cyclization reaction of a methoxycarbonyl group derived from the methyl (meth) acrylate (a) and a carboxyl group derived from the (meth) acrylic acid (B) adjacent to the methoxycarbonyl group in a copolymer obtained by copolymerizing the methyl (meth) acrylate (a) and the (meth) acrylic acid (B), and is derived from the methyl (meth) acrylate (a) and the (meth) acrylic acid (B), but the unit (C) is not contained in the unit (B).

From the viewpoint of excellent heat resistance of a molded article obtained by molding the thermoplastic resin composition of the present invention, the lower limit of the content of the unit (C) in the copolymer (P1) is 0.001 mol%, more preferably 0.005 mol%, and still more preferably 0.0075 mol% relative to the total mole number of the repeating units contained in the copolymer (P1). From the viewpoint of suppressing the molding coloring of the obtained molded article, and of excellent molding appearance and weather resistance, the upper limit of the content of the unit (C) in the copolymer (P1) is 0.15 mol%, more preferably 0.02 mol%, and still more preferably 0.015 mol%.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (C) in the copolymer (P1) is 0.001 mol% or more and 0.15 mol% or less, preferably 0.005 mol% or more and 0.02 mol% or less, and more preferably 0.0075 mol% or more and 0.015 mol% or less, based on the total mole number of the repeating units contained in the copolymer (P1).

In the present specification, the content of each unit in the copolymer is defined by¹H-NMR measurement of the calculated value.

The specific calculation method may be the method described in the examples.

The copolymer (P1) may contain a repeating unit derived from another monomer (D) (hereinafter, simply referred to as "unit (D)") in addition to the unit (a), the unit (B) and the unit (C).

The content of the unit (D) in the copolymer (P1) is preferably not contained in the copolymer (P1) from the viewpoint that the molded article obtained by molding the thermoplastic resin composition of the present invention does not impair the original performance of the acrylic resin. Even when the unit (D) is contained in the copolymer (P1), the content of the unit (D) in the copolymer (P1) is preferably more than 0 mol% and 15 mol% or less, more preferably more than 0 mol% and 5 mol% or less, relative to the total mole number of the repeating units contained in the copolymer (P1).

Examples of the other monomer (D) constituting the unit (D) include (meth) acrylic acid esters such as ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetracyclododecyl (meth) acrylate, and cyclohexanedimethanol mono (meth) acrylate, and aromatic vinyl monomers such as styrene and α -methylstyrene.

These monomers may be used alone or in combination of two or more.

When the thermoplastic resin composition of the present invention contains the antioxidant (O) represented by the above general formula (1) in an amount of 0.02 to 0.14 mass% based on the total mass of the thermoplastic resin composition, the copolymer (P1) preferably contains 80 mol% or more of the unit (a), 2 to 7 mol% or less of the unit (B), and 0.005 to 0.02 mol% or less of the unit (C), from the viewpoint of suppressing the molding coloring of a molded article, and further improving the molded appearance and weather resistance.

In the case where the thermoplastic resin composition of the present invention contains the antioxidant (O) represented by the above general formula (1) in an amount of 0.03 to 0.13% by mass based on the total mass of the thermoplastic resin composition, the copolymer (P1) preferably contains the unit (a) in an amount of 80 mol% or more, the unit (B) in an amount of 2 to 4 mol% or less, and the unit (C) in an amount of 0.0075 to 0.015 mol% or less, from the viewpoint of suppressing molding coloring of a molded article, and further improving molding appearance and weather resistance.

< (meth) acrylic acid methyl ester (a) >

Methyl (meth) acrylate (a) is a monomer that is a source of the unit (a) contained in the copolymer (P1) and the unit (a) contained in the copolymer (P2). In addition, a part of methyl (meth) acrylate (a) is a monomer which is a source of the unit (C) contained in the copolymer (P1) and the unit (C) contained in the copolymer (P2) together with a part of (meth) acrylic acid (b).

Methyl (meth) acrylate (a) means methyl methacrylate or methyl acrylate, or a mixture thereof.

Among the methyl (meth) acrylates (a), methyl (meth) acrylate is preferably used as the main component thereof, from the viewpoint of excellent transparency of a molded article obtained by molding the thermoplastic resin composition of the present invention. In addition, from the viewpoint of improving the thermal decomposition resistance of the copolymer (P1) in the thermoplastic resin composition of the present invention and the copolymer (P2) in the molded article of the present invention, it is more preferable to use methyl acrylate together with methyl methacrylate.

In the present specification, the term "main component" means a component that is contained in an amount of 70 mass% or more based on the total mass (100 mass%).

From the viewpoint of excellent transparency of the resulting molded article, the unit (a) is preferably composed mainly of a repeating unit derived from methyl methacrylate as well. Further, from the viewpoint of improving the thermal decomposition resistance of the copolymer (P1) in the thermoplastic resin composition of the present invention and the copolymer (P2) in the molded article of the present invention, it is more preferable to contain both a repeating unit derived from methyl acrylate and a repeating unit derived from methyl methacrylate.

(meth) acrylic acid (b) >

(meth) acrylic acid (B) is a monomer which is a source of the unit (B) contained in the copolymer (P1) of the present invention and the unit (B) contained in the copolymer (P2) of the present invention. Further, a part of (meth) acrylic acid (b) is a monomer which is a source of the unit (C) contained in the copolymer (P1) and the unit (C) contained in the copolymer (P2) together with a part of methyl (meth) acrylate (a).

(meth) acrylic acid (b) means acrylic acid or methacrylic acid, or a mixture thereof.

Among (meth) acrylic acid (b), methacrylic acid is preferable because a molded article obtained by molding the thermoplastic resin composition of the present invention has excellent heat resistance.

The unit (B) is also preferably a repeating unit derived from methacrylic acid in the same manner from the viewpoint of excellent heat resistance of the obtained molded article.

< method for producing copolymer (P1) >

In order to obtain a copolymer (P1) containing 80 mol% or more of the units (a), 2 mol% or more and 7 mol% or less of the units (B), and 0.001 mol% or more and 0.15 mol% or less of the units (C), a polymerization composition containing a precursor of the copolymer (P1) (hereinafter, simply referred to as "copolymer (P1) precursor") is obtained by polymerizing a monomer composition (M) containing methyl (meth) acrylate (a) and (meth) acrylic acid (B) at an appropriate molar ratio, and then the obtained copolymer (P1) precursor is subjected to a cyclization reaction with the units (a) and (B) in the precursor to form the units (C) by using a heating mechanism such as an injection molding machine or an extruder.

The heating temperature at which the cyclization reaction of the precursor is carried out using a heating mechanism such as an injection molding machine or an extruder is preferably 200 ℃ to 270 ℃, and more preferably 210 ℃ to 260 ℃ in terms of excellent productivity of the copolymer or the resin composition and suppression of thermal deterioration of the copolymer. The heating time is preferably 1 to 2400 seconds, more preferably 5 to 1800 seconds, and still more preferably 10 to 1200 seconds, from the viewpoint that the copolymer (P1) can be sufficiently mixed and thermal degradation of the copolymer (P1) can be suppressed.

When the copolymer (P1) contains the unit (D), it can be produced by using a monomer composition (M) containing a monomer (D) other than the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), thereby obtaining a copolymer (P1) containing the unit (D).

< monomer composition (M) >

The monomer composition (M) is a raw material of the precursor of the above-mentioned copolymer (P1).

The monomer composition (M) is a monomer composition comprising methyl (meth) acrylate (a) and (meth) acrylic acid (b).

The lower limit of the content of the methyl (meth) acrylate (a) in the monomer composition (M) is not particularly limited, but is preferably 80 mol%, more preferably 90 mol% of 100 mol% of the monomer composition (M) from the viewpoint of the appearance, low water absorption, and moldability of a molded article obtained by molding the thermoplastic resin composition of the present invention, and the inherent performance of the acrylic resin is not impaired. The upper limit of the content of the methyl (meth) acrylate (a) in the monomer composition (M) is not particularly limited, but is preferably 99.5 mol% or less, more preferably 99 mol% or less, of 100 mol% of the monomer composition (M) in view of excellent heat resistance and mechanical properties of the resulting molded article.

The content of the methyl (meth) acrylate (a) in the monomer composition (M) is more preferably 80 mol% or more and 99.5 mol% or less, and still more preferably 90 mol% or more and 99 mol% or less.

The lower limit of the content of the (meth) acrylic acid (b) in the monomer composition (M) is not particularly limited, but is preferably 2.0 mol%, more preferably 2.5 mol% of 100 mol% of the monomer composition (M) from the viewpoint of excellent heat resistance and mechanical properties of a molded article obtained by molding the thermoplastic resin composition of the present invention. The upper limit of the content of the (meth) acrylic acid (b) in the monomer composition (M) is not particularly limited, but is preferably 7.0 mol%, more preferably 6.0 mol% in 100 mol% of the monomer composition (M) from the viewpoint of appearance, low water absorption, excellent moldability of the resulting molded article, and no deterioration in the inherent performance of the acrylic resin.

The content of (meth) acrylic acid (b) in the monomer composition (M) is preferably 2.0 mol% or more and 7.0 mol% or less, and more preferably 2.5 mol% or more and 6.0 mol% or less.

The monomer composition (M) may contain other monomer (d) in addition to the methyl (meth) acrylate (a) and the (meth) acrylic acid (b).

The other monomer (D) may be the same as the "monomer constituting the unit (D)" as long as it is copolymerizable with the methyl (meth) acrylate (a) and the (meth) acrylic acid (b).

The content of the other monomer (d) in the monomer composition (M) is preferably not contained in the monomer composition (M) from the viewpoint that the resin composition does not impair the original performance of the acrylic resin. In addition, even when the monomer composition (M) contains another monomer (d), it is preferably more than 0 mol% and 15 mol% or less, and more preferably more than 0 mol% and 5 mol% or less, in 100 mol% of the monomer composition (M).

As a method for obtaining a polymer composition containing the precursor of the copolymer (P1) by polymerizing the monomer composition (M), for example, a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization can be used. In the polymerization of the monomer composition (M), the polymerization temperature, the kind of the polymerization initiator, the amount of the polymerization initiator, and the like may be appropriately set by those skilled in the art based on known techniques.

< copolymer (P2) >

The copolymer (P2) is one of the constituents of the molded article of the invention.

When the molded article of the present invention contains the copolymer (P2), the molded article has excellent heat resistance.

The copolymer (P2) of the present invention comprises the unit (a), the unit (B), and the unit (C).

From the viewpoint of not impairing the original performance of the acrylic resin, such as excellent transparency and processability and mechanical properties of the molded article of the present invention, the lower limit of the content of the unit (a) in the copolymer (P2) is 80 mol%, more preferably 90 mol%, based on the total mole number of the repeating units contained in the copolymer (P2). The upper limit value of the content of the unit (a) in the copolymer (P1) is 97.99 mol%, and from the viewpoint of excellent heat resistance of the molded article of the present invention, it is preferably 97 mol%, and more preferably 96 mol%.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (a) in the copolymer (P2) is preferably 80 mol% or more and 97.99 mol% or less, more preferably 90 mol% or more and 97 mol% or less, based on the total number of moles of the repeating units contained in the copolymer (P2).

The repeating unit (C) having a glutaric anhydride structure is a unit which is constructed by a cyclization reaction of a methoxycarbonyl group derived from the methyl (meth) acrylate (a) and a carboxyl group derived from the (meth) acrylic acid (b) adjacent to the methoxycarbonyl group in a copolymer obtained by copolymerizing the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), and is derived from the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), but the unit (a) does not include the unit (C).

From the viewpoint of excellent heat resistance and mechanical properties of the molded article of the present invention, the lower limit of the content of the unit (B) in the copolymer (P2) is 2 mol%, more preferably 2.5 mol%, based on the total mole number of the repeating units contained in the copolymer (P2). From the viewpoint of not impairing the original performance of the acrylic resin, such as molded appearance, low water absorption, and excellent moldability of the molded article of the present invention, the upper limit of the content of the unit (B) in the copolymer (P2) is 7 mol%, more preferably 3.5 mol%.

The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (B) in the copolymer (P2) is preferably 2 mol% or more and 7 mol% or less, more preferably 2 mol% or more and 3.5 mol% or less, relative to the total number of moles of the repeating units contained in the copolymer (P2).

The repeating unit (C) having a glutaric anhydride structure is a unit which is constructed by a cyclization reaction of a methoxycarbonyl group derived from the methyl (meth) acrylate (a) and a carboxyl group derived from the (meth) acrylic acid (b) adjacent to the methoxycarbonyl group in a copolymer obtained by copolymerizing the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), and is derived from the methyl (meth) acrylate (a) and the (meth) acrylic acid (b), but the unit (a) does not include the unit (C).

From the viewpoint of excellent heat resistance of the molded article of the present invention, the lower limit of the content of the unit (C) in the copolymer (P2) is 0.01 mol%, more preferably 0.02 mol%, and still more preferably 0.03 mol% relative to the total mole number of the repeating units contained in the copolymer (P2). From the viewpoint of suppressing the molding coloration of the molded article of the present invention, and of excellent molding appearance and weather resistance, the upper limit of the content of the unit (C) in the copolymer (P2) is 2 mol%. More preferably 1.2 mol%, and still more preferably 0.6 mol%. The above-described preferable upper limit value and preferable lower limit value may be arbitrarily combined, and a preferable combination of the upper limit value and the lower limit value is constituted. For example, the content of the unit (C) in the copolymer (P2) is 0.01 mol% or more and 2 mol% or less, preferably 0.02 mol% or more and 1.2 mol% or less, and more preferably 0.03 mol% or more and 0.6 mol% or less, based on the total mole number of the repeating units contained in the copolymer (P2).

The copolymer (P2) may contain the unit (D) in addition to the unit (a), the unit (B), and the unit (C).

The content of the unit (D) in the copolymer (P2) is preferably not contained in the copolymer (P2) from the viewpoint that the molded article does not impair the original performance of the acrylic resin. Even when the unit (D) is contained in the copolymer (P2), the content of the unit (D) in the copolymer (P2) is preferably more than 0 mol% and 15 mol% or less, more preferably more than 0 mol% and 5 mol% or less, relative to the total mole number of the repeating units contained in the copolymer (P2).

In the case where the molded article of the present invention contains the antioxidant (O) represented by the above general formula (5) in an amount of 0.002% by mass or more and 0.03% by mass or less with respect to the total mass of the molded article, the copolymer (P2) preferably contains 80 mol% or more of the unit (a), 2 mol% or more and 7 mol% or less of the unit (B), and 0.02 mol% or more and 1.2 mol% or less of the unit (C), from the viewpoint of suppressing the molding coloring of the molded article, and further improving the molded appearance and weather resistance.

In the case where the molded article of the present invention contains the antioxidant (O) represented by the above general formula (5) in an amount of 0.01 to 0.025 mass% based on the total mass of the molded article, the copolymer (P2) preferably contains 80 mol% or more of the unit (a), 2 mol% or more and 3.5 mol% or less of the unit (B), and 0.03 mol% or more and 0.6 mol% or less of the unit (C), from the viewpoint of further improving the molding coloration of the molded article, the molded appearance, and the weather resistance.

< antioxidant (O) >

The antioxidant (O) is one of the components of the thermoplastic resin composition of the present invention and the molded article of the present invention.

The thermoplastic resin composition of the present invention contains the antioxidant (O) represented by the following general formula (1), and therefore, the molded article obtained by molding the thermoplastic resin composition of the present invention is excellent in the suppression of molding coloring, molding appearance, and weather resistance.

[ solution 10]

[ in the formula (1), R¹And R^1’Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.]

The antioxidant (O) is more preferably a compound having a structure represented by the following general formula (2).

[ solution 11]

[ in the formula (2), R²And R^2’Each independently represents an alkyl group having 1 to 8 carbon atoms.]

When the thermoplastic resin composition of the present invention contains the copolymer (P1) and the antioxidant (O) having the above structure, the coloration of the thermoplastic resin composition during molding can be greatly suppressed, and a molded article obtained by molding the thermoplastic resin composition can be suppressed in coloration and exhibit excellent transparency. Further, by melt-kneading the components using the antioxidant (O), the content of the unreacted methyl (meth) acrylate (a) and the unreacted (meth) acrylic acid (b) (hereinafter, simply referred to as "residual monomer") contained in the particulate thermoplastic resin composition obtained is reduced, and a molded article obtained by molding the thermoplastic resin composition of the present invention is less likely to cause appearance defects such as silver streaks, and a molded article having a good appearance can be obtained.

Further, the molded article of the present invention contains an antioxidant (O) represented by the following general formula (5), whereby the coloring in molding can be suppressed, and the molded appearance and weather resistance can be improved.

[ solution 12]

[ in the formula (5), R⁵And R^5’Each independently represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at an arbitrary position on the phenyl group.]

The antioxidant (O) is more preferably a compound having a structure represented by the following general formula (6).

[ solution 13]

[ in the formula (6), R⁶And R^6’Each independently represents an alkyl group having 1 to 8 carbon atoms.]

< phenolic Compound >

The thermoplastic resin composition of the present invention may contain a phenol compound having a structure represented by the following general formula (3) as a constituent component.

[ solution 14]

[ in the formula (3), R³Represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at any position on the phenyl group.]

The phenolic compound contained in the thermoplastic resin composition of the present invention contains a compound derived from a decomposition product of the antioxidant (O) blended in the precursor of the copolymer (P1).

Here, the "compound substantially derived from a decomposition product of the antioxidant (O) blended in the precursor of the copolymer (P1)" does not originate from a compound previously contained as an additive such as a stabilizer in a monomer raw material, but means a compound generated by thermal decomposition of the antioxidant (O) blended in the precursor of the copolymer (P1). More specifically, the term "means a compound in which 90% by mass or more of the phenolic compound contained in the thermoplastic resin composition of the present invention is derived from the thermal decomposition of the antioxidant (O) blended in the precursor of the copolymer (P1).

By including the phenolic compound in the thermoplastic resin composition of the present invention, the coloring of a molded article obtained by molding the thermoplastic resin composition of the present invention is suppressed, and the molded appearance and weather resistance are improved.

The phenolic compound contained in the thermoplastic resin composition of the present invention is more preferably a compound having a structure represented by the following general formula (4).

[ solution 15]

[ in the formula (4), R⁴Represents an alkyl group having 1 to 8 carbon atoms.]

The content of the phenolic compound in the thermoplastic resin composition of the present invention is not particularly limited, but is preferably 0.001 mass% or more and 0.4 mass% or less, more preferably 0.005 mass% or more and 0.2 mass% or less, and further preferably 0.008 mass% or more and 0.1 mass% or less, from the viewpoints of suppressing coloring of a molded article obtained by molding the thermoplastic resin composition of the present invention and improving molding appearance and weather resistance.

The content of the phenolic compound in the thermoplastic resin composition of the present invention can be controlled by adjusting the amount of the antioxidant (O) blended, the temperature and time at the time of melt-kneading, and the like in the method for producing a thermoplastic resin composition described later.

The molded article of the present invention may contain a phenolic compound having a structure represented by the following general formula (7) as a constituent component.

[ solution 16]

[ in the formula (7), R⁷Represents a single or multiple alkyl groups having 1 to 8 carbon atoms substituted at any position on the phenyl group.]

The phenolic compound contained in the molded article of the present invention includes a compound derived from a decomposition product of the antioxidant (O) blended in the precursor of the copolymer (P1) or a decomposition product of the antioxidant (O) contained in the thermoplastic resin composition of the present invention.

Here, the phrase "compound substantially derived from a decomposition product of the antioxidant (O) blended in the precursor of the copolymer (P1) or a decomposition product of the antioxidant (O) contained in the thermoplastic resin composition of the present invention" does not originate from a compound contained in advance as an additive such as a stabilizer in a monomer raw material, but means a compound generated by thermally decomposing the antioxidant (O) blended in the precursor of the copolymer (P1) or the antioxidant (O) contained in the thermoplastic resin composition of the present invention. More specifically, the term "means a compound in which 90% by mass or more of the phenolic compound contained in the molded article of the present invention is derived from the thermal decomposition of the antioxidant (O) blended in the precursor of the copolymer (P1) or the antioxidant (O) contained in the thermoplastic resin composition of the present invention.

The molded article of the present invention contains the above phenolic compound, whereby coloration is suppressed, and the molded appearance and weather resistance are improved.

The phenolic compound contained in the molded article of the present invention is more preferably a compound having a structure represented by the following general formula (8).

[ solution 17]

[ in the formula (8), R⁸Represents an alkyl group having 1 to 8 carbon atoms.]

The content of the phenolic compound in the molded article of the present invention is preferably 0.001 mass% or more and 0.4 mass% or less, more preferably 0.005 mass% or more and 0.2 mass% or less, and still more preferably 0.01 mass% or more and 0.1 mass% or less, from the viewpoint of suppressing molding coloration of the molded article of the present invention and improving the molded appearance.

< method for producing thermoplastic resin composition >

The thermoplastic resin composition of the present invention can be produced by the following methods (1) and (2).

(1) A method of melt-mixing the precursor of the copolymer (P1) and the antioxidant (O) by a known melt-kneading means (formation of the unit (C) by melt-mixing)

(2) A method in which the copolymer (P1) and the antioxidant (O) are melt-mixed by a known melt-kneading means (the unit (C) is further formed by melt-mixing)

The details are as described in the above-mentioned method for producing the copolymer (P1).

Examples of the known melt kneading means include a single screw extruder, a twin screw extruder, a banbury mixer, a Brabender (Brabender), and a roll mill. The molding may be performed directly by extrusion molding, sheet molding, or the like while melt kneading. Among them, melt kneading by a twin-screw extruder is particularly preferable from the viewpoint of excellent mixing efficiency.

< other additives >

The thermoplastic resin composition of the present invention may further contain other additives in addition to the copolymer (P1) and the antioxidant (O).

Examples of the other additives include ultraviolet absorbers, antioxidants, light stabilizers, plasticizers, light diffusers, delustering agents, lubricants, mold release agents, antistatic agents, impact strength modifiers, fluidity modifiers, slip agents, pigments, colorants such as dyes, and the like. These other additives may be used alone or in combination of two or more.

The above-mentioned other additives may be added when the precursor of the copolymer (P1) of the present invention and the antioxidant (O) are mixed, or may be added or mixed to the thermoplastic resin composition of the present invention.

Since the deflection temperature under load (HDT) of a molded article obtained by molding the thermoplastic resin composition of the present invention is 105 ℃ or higher, the obtained molded article has excellent heat resistance. In the present specification, the deflection temperature under load is a value measured according to ISO 75-1.2.

The content of the residual monomer in the thermoplastic resin composition of the present invention is preferably 0.5% by mass or less with respect to the total mass of the thermoplastic resin composition.

When the residual monomer content is 0.5% by mass or less, appearance defects such as silver streaks can be suppressed from occurring in the molded article when the thermoplastic resin composition of the present invention is molded, and the resulting molded article is further excellent in thermal stability and weather resistance.

The upper limit of the content of the residual monomer in the thermoplastic resin composition of the present invention is more preferably 0.4% by mass, still more preferably 0.3% by mass, and particularly preferably no residual monomer is contained. In the present specification, the term "residual monomer" refers to the unreacted methyl (meth) acrylate (a) and the unreacted (meth) acrylic acid (b) contained in the thermoplastic resin composition. Further, in the case where the copolymer (P1) contains the unit (D), "residual monomer" further contains the other unreacted monomer (D) contained in the thermoplastic resin composition.

< method for producing molded article >

The molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention.

The method for obtaining the molded article of the present invention is not particularly limited, and examples thereof include a method of molding the thermoplastic resin composition of the present invention by a known molding means such as an injection molding method, an extrusion molding method, or a press molding method. The molded article obtained may be further subjected to secondary molding by a known molding method such as a press-air molding method or a vacuum molding method.

The molded article of the present invention can be obtained by molding the thermoplastic resin composition of the present invention. Therefore, when the deflection temperature under load (HDT) of the obtained molded article is 105 ℃ or more and measured as a flat molded article having a thickness of 3mm, the total light transmittance can be 90% or more, the haze value can be 1.0% or less, and the yellowness index value can be 0.6 or less. Therefore, the molded article of the present invention is excellent in heat resistance, transparency, and molding coloring. For the above reasons, the molded article has excellent appearance and weather resistance.