Graft copolymer, thermoplastic resin composition, and molded article produced by molding the same

Abstract

A graft copolymer (B) produced by graft polymerization of a vinyl monomer mixture (m1) including an alkyl (meth)acrylate ester onto a copolymer (A), the copolymer (A) being a copolymer of an alkyl (meth)acrylate ester (Aa) and a (meth)acrylate ester (Ab) including an aromatic hydrocarbon group. A thermoplastic resin composition including the graft copolymer (B), a copolymer (C) that is the product of a polymerization reaction of a vinyl monomer mixture (m2) including an alkyl (meth)acrylate ester, and a molded article produced by molding the thermoplastic resin composition. Provided are the graft copolymer with which a thermoplastic resin composition excellent in terms of transparency, impact resistance, weather resistance, and flowability may be produced, a thermoplastic resin composition including the graft copolymer, and the molded article produced by molding the thermoplastic resin composition.

Claims

1. A graft copolymer (B) produced by graft polymerization of a vinyl monomer mixture (m1) including an alkyl (meth)acrylate ester, a vinyl cyanide compound, and an aromatic vinyl compound onto a copolymer (A), the copolymer (A) being a copolymer of an alkyl (meth)acrylate ester (Aa) and a (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, wherein, relative to 100% by mass of a total content of a unit of the alkyl (meth)acrylate ester (Aa) and a unit of the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group in the copolymer (A), a content of the unit of the alkyl (meth)acrylate ester (Aa) in the copolymer (A) is 70% to 90% by mass and a content of the unit of the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group in the copolymer (A) is 10% to 30% by mass, wherein a content of the alkyl (meth)acrylate ester in the vinyl monomer mixture (m1) is 20% to 30% by mass, a content of the vinyl cyanide compound in the vinyl monomer mixture (m1) is 10% to 20% by mass, and a content of the aromatic vinyl compound in the vinyl monomer mixture (m1) is 50% to 60% by mass, and wherein the copolymer (A) includes a unit of the alkyl (meth)acrylate ester (Aa), a unit of the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, and a unit derived from a crosslinking agent and/or a unit derived from a graft-crossing agent.

2. The graft copolymer (B) according to claim 1, wherein a content of the unit derived from a crosslinking agent and/or a graft-crossing agent in the copolymer (A) is 0.1% to 3% by mass, relative to 100% by mass of a total content of the unit of the alkyl (meth)acrylate ester (Aa), the unit of the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, and the unit derived from a crosslinking agent and/or a graft-crossing agent.

3. The graft copolymer (B) according to claim 1, wherein the copolymer (A) is produced by miniemulsion polymerization of a mixture including the alkyl (meth)acrylate ester (Aa), the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, a crosslinking agent and/or a graft-crossing agent, a hydrophobic substance, and an initiator.

4. The graft copolymer (B) according to claim 1, wherein the copolymer (A) has a volume-average particle size of 0.05 to 0.80 μm and a degree of swelling, measured according to a description, of 2 to 15 times.

5. The graft copolymer (B) according to claim 1, wherein, relative to 100% by mass of a total content of the copolymer (A) and the vinyl monomer mixture (m1), a content of the copolymer (A) is 50% to 80% by mass and a content of the vinyl monomer mixture (m1) is 20% to 50% by mass, and the graft copolymer (B) has a graft ratio, measured according to the description, of 25% to 100%.

6. A thermoplastic resin composition comprising the graft copolymer (B) according to claim 1.

7. The thermoplastic resin composition according to claim 6, further comprising, in addition to the graft copolymer (B), a copolymer (C) that is the product of a polymerization reaction of a vinyl monomer mixture (m2) including an alkyl (meth)acrylate ester.

8. The thermoplastic resin composition according to claim 7, wherein the vinyl monomer mixture (m2) includes an alkyl (meth)acrylate ester having the same structure as the alkyl (meth)acrylate ester included in the vinyl monomer mixture (m1), and a content of the alkyl (meth)acrylate ester in the vinyl monomer mixture (m2) is 60% to 100% by mass.

9. The thermoplastic resin composition according to claim 7, wherein, relative to 100% by mass of a total content of the graft copolymer (B) and the copolymer (C), a content of the graft copolymer (B) is 10% to 50% by mass and a content of the copolymer (C) is 50% to 90% by mass.

10. A molded article produced by molding the thermoplastic resin composition according to claim 6.

Description

EXAMPLES

(1) The present invention is described below further specifically with reference to Examples and Comparative examples below. The present invention is not limited to Examples below without departing from the scope of the present invention.

(2) Hereinafter, the expression “part” means “part by mass”, and the expression “%” means “% by mass”.

Methods for Measuring Physical Properties of Copolymer (A), Graft Copolymer (B), and Copolymer (C)

(3) The methods for measuring the physical properties of the copolymer (A), the graft copolymer (B), and the copolymer (C) used in Examples and Comparative examples below are as follows.

Volume-Average Particle Size of Copolymer (A)

(4) The volume-average particle size of the copolymer (A) dispersed in an aqueous dispersion was measured with MICROTRAC (“NANOTRAC 150” produced by Nikkiso Co., Ltd.) using ion-exchange water as a measurement solvent.

Degree of Swelling of Copolymer (A)

(5) The copolymer (A) was dried at 80° C. for 24 hours and then dried in vacuum at 80° C. for 24 hours. Hereby, a film-like dried copolymer (A) was prepared. Hereinafter, the weight of the dried copolymer (A) is represented by W1. The dried copolymer (A) was immersed in acetone for 12 hours at normal temperature and subsequently filtered through a 200-mesh metal screen. The weight of the residue was measured. Hereinafter, the weight of the residue is represented by W2. Subsequently, the residue was dried in vacuum for 24 hours at normal temperature. The weight of the dried residue measured after vacuum drying is represented by W3. The degree of swelling of the copolymer (A) is calculated using Formula (1) below.
Degree of swelling (%)=(W2/W3)×100   (1)

Graft Ratio of Graft Copolymer (B)

(6) To 80 mL of acetone, 1 g of the graft copolymer (B) was added. The resulting mixture was heated to 65° C. to 70° C. for 3 hours to reflux. The resulting suspended acetone solution was subjected to centrifugation at 14,000 rpm for 30 minutes with a centrifugal separation apparatus (“CR21E” produced by Hitachi, Ltd.) in order to separate a precipitate component (component insoluble in acetone) and an acetone solution (component soluble in acetone) from each other.

(7) The precipitation component (component insoluble in acetone) was dried and the mass (Y(g)) of the dried precipitation component was measured. The graft ratio was calculated using Formula (2) below.

(8) In Formula (2), Y is the mass (g) of the component of the graft copolymer (B) which is insoluble in acetone; X is the total mass (g) of the graft copolymer (B) used in the measurement of Y; and the rubber proportion is the concentration of the solid component in the aqueous dispersion of the copolymer (A) which was used in the production of the graft copolymer (B).
Graft Ratio (mass %)={(Y−X×Rubber proportion)/X×Rubber proportion}×100   (2)

Mass-Average Molecular Weight of Copolymer (C)

(9) The mass-average molecular weight of the copolymer (C) was measured by gel permeation chromatography (GPC) using a sample prepared by dissolving the copolymer (C) in tetrahydrofuran (THF) in terms of polystyrene (PS) standards.

Methods for Measuring and Evaluating Thermoplastic Resin Composition

(10) The method for measuring the physical properties of the thermoplastic resin compositions prepared in Examples and Comparative examples below, the methods for evaluating the characteristics of the thermoplastic resin compositions, and the molding methods used for the evaluations are as described below.

Measurement of Melt Volume Rate (MVR)

(11) The MVR of the thermoplastic resin composition at 220° C. was measured with a load of 98 N (10 kg) in accordance with ISO 1133:1997. MVR is a measure of the flowability of the thermoplastic resin composition. The higher the MVR value, the higher the degree of flowability.

Injection Molding 1

(12) A pellet of the thermoplastic resin composition produced by melt kneading was molded into a molded article having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm using an injection molding machine (“IS55FP-1.5A” produced by Toshiba Machine Co., Ltd.) at a cylinder temperature of 200° C. to 270° C. and a mold temperature of 60° C. This molded article was used as a molded article for Charpy impact test (molded article (Ma1)).

Injection Molding 2

(13) A pellet of the thermoplastic resin composition produced by melt kneading was molded into a molded article having a length of 100 mm, a width of 100 mm, and a thickness of 3 mm using an injection molding machine (“IS55FP-1.5A” produced by Toshiba Machine Co., Ltd.) at a cylinder temperature of 200° C. to 270° C. and a mold temperature of 60° C. This molded article was used as a molded article for transparency and weather resistance evaluation (molded article (Ma2)).

Transparency Evaluation

(14) The haze (Hz) of the molded article (Ma2) was measured with a haze meter (produced by MURAKAMI COLOR RESEARCH LABORATORY CO., LTD.). The lower the haze, the higher the degree of transparency.

Impact Resistance Evaluation: Charpy Impact Test

(15) The Charpy impact strength (impact direction: edgewise) of the molded article (Ma1) (Type B1, with notch: Shape A single notch) was measured in accordance with ISO 179-1:2013 at a test temperature of 23° C. The higher the Charpy impact strength, the higher the degree of impact resistance.

Weather Resistance Evaluation

(16) The molded article (Ma2) was treated with Sunshine Weather Meter (produced by Suga Test Instruments Co., Ltd.) at a black panel temperature of 63° C. under a cycle condition of 60 minutes (rainfall: 12 minutes) for 1500 hours. The haze was measured before and after the treatment with a haze meter (produced by MURAKAMI COLOR RESEARCH LABORATORY CO., LTD.), and the change (ΔHz) in haze was determined. The smaller the ΔHz value, the higher the degree of weather resistance.

Production of Copolymer (C)

Production of Copolymer (C-1)

(17) Into a pressure-resistant reaction container, 150 parts of ion-exchange water, a mixture of 99 parts of methyl methacrylate and 1 part of methyl acrylate, which was used as a vinyl monomer mixture (m2), 0.2 parts of 2,2′-azobis(isobutyronitrile), 0.45 parts of n-octyl mercaptan, 0.47 parts of calcium hydroxyapatite, and 0.003 parts of potassium alkenyl succinate were charged. Then, the internal temperature was increased to 75° C., and a reaction was conducted for 3 hours. Subsequently, the temperature was increased to 90° C., and holding was performed for 60 minutes to complete the reaction. The contents were repeatedly cleaned and dehydrated with a centrifugal dehydrator and then dried. Hereby, a copolymer (C-1) having a mass-average molecular weight of 124,000 was prepared.

Examples and Comparative Examples Where Vinyl Monomer Mixture (m1) Including Alkyl (Meth)acrylate Ester was Used

Production of Copolymers (A)

Production of Copolymer (A-I-1)

(18) A copolymer (A-I-1) having the following composition was prepared.

Composition

(19) n-Butyl acrylate (Aa): 42 parts

(20) 2-Phenoxyethyl acrylate (Ab): 18 parts

(21) Allyl methacrylate: 0.24 parts

(22) 1,3-Butylene glycol dimethacrylate: 0.12 parts

(23) Liquid paraffin: 0.6 parts

(24) Dipotassium alkenylsuccinate: 0.20 parts

(25) Dilauroyl peroxide: 0.6 parts

(26) Ion-exchange water: 406 parts

(27) Into a reaction container equipped with a reagent injection container, a cooling tube, a jacketed heater, and a stirring device, n-butyl acrylate, 2-phenoxyethyl acrylate, liquid paraffin, allyl methacrylate, dilauroyl peroxide, ion-exchange water, and dipotassium alkenylsuccinate were charged. Subsequently, an ultrasound treatment was performed with ULTRASONIC HOMOGENIZER US-600 produced by NIHONSEIKI KAISHA LTD. at an amplitude of 35 μm for 20 minutes at normal temperature to prepare a pre-emulsion. The volume-average particle size of the resulting latex was 250 nm.

(28) The pre-emulsion was heated to 60° C. to initiate radical polymerization. As a result of the polymerization reaction, the liquid temperature was increased to 78° C. The temperature was maintained at 75° C. for 30 minutes to complete the polymerization reaction. Hereby, an aqueous dispersion of a copolymer (A-I-1) having a volume-average particle size of 300 nm was prepared.

Preparation of Copolymers (A-I-2) to (A-I-17)

(29) Aqueous dispersions of copolymers (A-I-2) to (A-I-17) were prepared as in the preparation of the copolymer (A-I-1), except that the amounts of the alkyl (meth)acrylate ester (Aa), the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, the dipotassium alkenylsuccinate, and the other monomers used were changed as described in Tables 1A and 1B.

Preparation of Copolymer (A-I-18)

(30) Into a stainless steel autoclave (hereinafter, referred to simply as “SUS autoclave”), 145 parts of ion-exchange water (hereinafter, referred to simply as “water”), 1.0 parts of potassium rosinate, 1.0 parts of potassium oleate, 0.06 parts of sodium hydroxide, 0.4 parts of sodium sulfate, and 0.3 parts of t-dodecyl mercaptan were charged. After nitrogen purging had been performed, 125 parts of 1,3-butadiene was charged into the autoclave. Then, the temperature was increased to 60° C.

(31) Subsequently, an aqueous solution prepared by dissolving 0.3 parts of potassium persulfate in 5 parts of water was pressure-injected into the autoclave to initiate polymerization. In the polymerization reaction, the polymerization temperature was adjusted to be 65° C. After a lapse of 12 hours, the unreacted portion of 1,3-butadiene was collected when the internal pressure reached 4.5 kg/cm.sup.2 (gage pressure). Subsequently, the internal temperature was changed to 80° C. and then holding was performed for 1 hour. Hereby, a butadiene rubber latex having a volume-average particle size of 250 nm and a solid content of 41% was prepared.

(32) Into a 5-liter glass reaction container, 20 parts of the butadiene rubber latex was charged in terms of solid content. Subsequently, 1.0 parts of dipotassium alkenylsuccinate and 150 parts of water were added to the container, which was then purged with nitrogen. Subsequently, the internal temperature was increased to 70° C. To the container, an aqueous solution prepared by dissolving 0.12 parts of potassium persulfate in 10 parts of water was added. Subsequently, a monomer mixture including 79.5 parts of n-butyl acrylate (Aa), 0.33 parts of allyl methacrylate, and 0.17 parts of 1,3-butylene glycol dimethacrylate, which had been purged with nitrogen, was continuously added dropwise to the container over 2 hours. After the completion of the addition of the monomer mixture, the internal temperature was increased to 80° C. and holding was performed for 1 hour. Hereby, an aqueous dispersion of a copolymer (A-I-18) that was constituted by a butadiene rubber and an acrylic rubber and had a volume-average particle size of 300 nm was prepared.

(33) Tables 1A and 1B summarize the degree of swelling and volume-average particle size of each of the copolymers (A-I-1) to (A-I-18).

(34) TABLE-US-00001 TABLE 1A Copolymer (A) A-I-1 A-I-2 A-I-3 A-I-4 A-I-5 A-I-6 A-I-7 A-I-8 A-I-9 A-I-10 Raw n-Butyl acrylate 42 42 42 44.4 40.8 39.6 36.6 33 47.4 52.2 material 2-Phenoxyethyl acrylate 18 18 18 15.6 19.2 20.4 23.4 27 12.6 7.8 composition Styrene (part) Butadiene rubber Dipotassium 0.20 1.50 0.11 0.20 0.20 0.20 0.20 0.20 0.20 0.20 alkenylsuccinate 1,3-Butylene glycol 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 dimethacrylate Allyl methacrylate 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 Degree of swelling (time) 6.2 6.2 6.4 6.2 6.3 6.2 6.2 6.4 6.5 6.4 Volume-average particle size (nm) 300 120 550 300 300 300 300 300 300 300 Remark For Examples

(35) TABLE-US-00002 TABLE 1B Copolymer (A) A-I-11 A-I-12 A-I-13 A-I-14 A-I-15 A-I-16 A-I-17 A-I-18 Raw n-Butyl acrylate 54 30 60 60 60 42 48 48 material 2-Phenoxyethyl acrylate 6 3 composition Styrene 18 12 (part) Butadiene rubber 12 Dipotassium 0.20 0.20 0.20 1.5 0.11 0.20 0.20 0.60 alkenylsuccinate 1,3-Butylene glycol 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.10 dimethacrylate Allyl methacrylate 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.20 Degree of swelling (time) 6.1 6.2 6.2 6.4 6.2 6.2 6.2 6.2 Volume-average particle size (nm) 300 300 300 120 550 300 300 300 Remark For Examples For Comparative examples

Preparation of Graft Copolymers (B)

Preparation of Graft Copolymer (B-I-1)

(36) After the preparation of the copolymer (A-I-1), while the internal temperature of the reaction container was maintained to be 75° C., relative to 60 parts (in terms of solid content) of the copolymer (A-I-1), an aqueous solution containing 0.001 parts of ferrous sulfate, 0.003 parts of a disodium ethylenediaminetetraacetate salt, 0.3 parts of Rongalite, and 5 parts of ion-exchange water was added to the container. Subsequently, an aqueous solution containing 0.65 parts of dipotassium alkenylsuccinate and 10 parts of ion-exchange water was added to the container. Subsequently, a mixture of 39.6 parts of methyl methacrylate and 0.4 parts of methyl acrylate, which was used as a vinyl monomer mixture (m1), and 0.18 parts of t-butyl hydroperoxide were added dropwise to the container over 1 hour 30 minutes to cause graft polymerization.

(37) After the completion of the addition of the mixture, the internal temperature was maintained to be 75° C. for 10 minutes. Subsequently, cooling was performed. When the internal temperature reached 60° C., an aqueous solution prepared by dissolving 0.2 parts of an antioxidant (ANTAGE W500 produced by YOSHITOMI PHARMACEUTICAL INDUSTRIES, LTD.) and 0.2 parts of dipotassium alkenylsuccinate in 5 parts of ion-exchange water was added to the container. The aqueous dispersion obtained as a reaction product was solidified using an aqueous sulfuric acid solution, cleaned with water, and then dried. Hereby, a graft copolymer (B-I-1) was prepared. The graft copolymer (B-I-1) had a graft ratio of 40%.

Preparation of Graft Copolymers (B-I-2) to (B-I-18)

(38) Graft copolymers (B-I-2) to (B-I-18) were prepared as in the preparation of the graft copolymer (B-I-1), except that the type of the copolymer (A) used was changed as described in Tables 2A and 2B.

(39) Tables 2A and 2B describe the graft ratios of the graft copolymers (B-I-2) to (B-I-18).

(40) TABLE-US-00003 TABLE 2A Graft copolymer (B) B-I-1 B-I-2 B-I-3 B-I-4 B-I-5 B-I-6 B-I-7 B-I-8 B-I-9 B-I-10 Copolymer A-I-1 60 (A) (part) A-I-2 60 A-I-3 60 A-I-4 60 A-I-5 60 A-I-6 60 A-I-7 60 A-I-8 60 A-I-9 60 A-I-10 60 Vinyl monomer Methyl methacrylate 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6 mixture (m1) Methyl acrylate 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 (part) Graft ratio (%) 40 41 40 39 40 39 40 41 40 40 Remark Invention example

(41) TABLE-US-00004 TABLE 2B Graft copolymer (B) B-I-11 B-I-12 B-I-13 B-I-14 B-I-15 B-I-16 B-I-17 B-I-18 Copolymer A-I-11 60 (A) (part) A-I-12 60 A-I-13 60 A-I-14 60 A-I-15 60 A-I-16 60 A-I-17 60 A-I-18 60 Vinyl monomer Methyl methacrylate 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6 mixture (m1) Methyl acrylate 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 (part) Graft ratio (%) 41 40 40 40 40 40 40 40 Remark Invention example Comparative example

Examples I-1 to I-12 and Comparative Examples I-1 to I-6

(42) The components were mixed with each other in the amounts (mass parts) described in Tables 3A and 3B. The resulting mixture was further mixed with 0.8 parts of carbon black. The mixture was then melt-kneaded at 240° C. with a twin-screw extruder (“PCM30” produced by Ikegai Corp) having a vacuum vent with a diameter of 30 mm to form a pellet-like thermoplastic resin composition. The melt volume rate of the thermoplastic resin composition was determined by the above-described method. The transparency, impact resistance, and weather resistance of a molded article prepared by injection-molding of the thermoplastic resin composition were evaluated by the above-described methods.

(43) Tables 3A and 3B describe the evaluation results.

(44) TABLE-US-00005 TABLE 3A Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple ple ple ple ple I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8 I-9 I-10 I-11 I-12 Graft B-I-1 28 copolymer B-I-2 28 (B) (part) B-I-3 28 B-I-4 28 B-I-5 28 B-I-6 28 B-I-7 28 B-I-8 28 B-I-9 28 B-I-10 28 B-I-11 28 B-I-12 28 Copolymer C-1 72 72 72 72 72 72 72 72 72 72 72 72 (C)(part) Charpy impact strength at 7.5 7.5 7.5 7.6 7.4 7.4 7.2 7 7.7 7.9 7.9 6.2 23° C. (kJ/m.sup.2) 220° C. MVR(cm.sup.3/10 min) 8.4 8.1 8.6 8.3 8.4 8.3 8.4 9.1 8.2 8.1 8.2 8.1 Transparency (Hz) 1.5 1.5 1.5 1.5 1.5 1.5 4.1 8.1 4.7 9.1 12 15 Weather resistance (ΔHz) 1.2 0.8 0.9 0.9 1.1 0.9 0.8 1.1 0.9 0.7 1.1 0.8

(45) TABLE-US-00006 TABLE 3B Comparative Comparative Comparative Comparative Comparative Comparative example I-1 example I-2 example I-3 example I-4 example I-5 example I-6 Graft B-I-13 28 copolymer B-I-14 28 (B) (part) B-I-15 28 B-I-16 28 B-I-17 28 B-I-18 28 Copolymer (C)(part) C-1 72 72 72 72 72 72 Charpy impact strength at 7.5 2.8 6.5 2.9 3.1 7.8 23° C. (kJ/m.sup.2) 220° C. MVR(cm.sup.3/10 min) 8.4 8.0 9.1 8.2 8.2 8.1 Transparency (Hz) 95 35 95 15 1.8 1.5 Weather resistance (ΔHz) 0.9 1.0 0.9 14 10 25

(46) The results obtained in Examples I-1 to I-12 described in Table 3A confirm that, in Examples, a thermoplastic resin composition and a molded article that had excellent impact resistance, excellent flowability, excellent transparency, and excellent weather resistance were prepared.

(47) In contrast, as described in Table 3B, the resin compositions and the molded articles prepared in Comparative examples I-1 to I-6 were significantly poor in terms of any of impact resistance, flowability, transparency, and weather resistance.

Examples and Comparative Examples Where Vinyl Monomer Mixture (m1) Including Alkyl (Meth)acrylate Ester, Vinyl Cyanide Compound, and Aromatic Vinyl Compound Was Used

Production of Copolymers (A)

Production of Copolymer (A-II-1)

(48) A copolymer (A-II-1) having the following composition was prepared.

Composition

(49) n-Butyl acrylate (Aa): 54 parts

(50) 2-Phenoxyethyl acrylate (Ab): 6 parts

(51) Allyl methacrylate: 0.24 parts

(52) 1,3-Butylene glycol dimethacrylate: 0.12 parts

(53) Liquid paraffin: 0.6 parts

(54) Dipotassium alkenylsuccinate: 0.20 parts

(55) Dilauroyl peroxide: 0.6 parts

(56) Ion-exchange water: 406 parts

(57) Into a reaction container equipped with a reagent injection container, a cooling tube, a jacketed heater, and a stirring device, n-butyl acrylate, 2-phenoxyethyl acrylate, liquid paraffin, allyl methacrylate, dilauroyl peroxide, ion-exchange water, and dipotassium alkenylsuccinate were charged. Subsequently, an ultrasound treatment was performed with ULTRASONIC HOMOGENIZER US-600 produced by NIHONSEIKI KAISHA LTD. at an amplitude of 35 μm for 20 minutes at normal temperature to prepare a pre-emulsion. The volume-average particle size of the resulting latex was 250 nm.

(58) The pre-emulsion was heated to 60° C. to initiate radical polymerization. As a result of the polymerization reaction, the liquid temperature was increased to 78° C. The temperature was maintained at 75° C. for 30 minutes to complete the polymerization reaction. Hereby, an aqueous dispersion of a copolymer (A-II-1) having a volume-average particle size of 300 nm was prepared.

Preparation of Copolymers (A-II-2) to (A-II-15)

(59) Aqueous dispersions of copolymers (A-II-2) to (A-II-15) were prepared as in the preparation of the copolymer (A-II-1), except that the amounts of the alkyl (meth)acrylate ester (Aa), the (meth)acrylate ester (Ab) including an aromatic hydrocarbon group, the dipotassium alkenylsuccinate, and the other monomers used were changed as described in Tables 4A and 4B.

Preparation of Copolymer (A-II-16)

(60) Into a stainless steel autoclave (hereinafter, referred to simply as “SUS autoclave”), 145 parts of ion-exchange water (hereinafter, referred to simply as “water”), 1.0 parts of potassium rosinate, 1.0 parts of potassium oleate, 0.06 parts of sodium hydroxide, 0.4 parts of sodium sulfate, and 0.3 parts of t-dodecyl mercaptan were charged. After nitrogen purging had been performed, 125 parts of 1,3-butadiene was charged into the autoclave. Then, the temperature was increased to 60° C.

(61) Subsequently, an aqueous solution prepared by dissolving 0.3 parts of potassium persulfate in 5 parts of water was pressure-injected into the autoclave to initiate polymerization. In the polymerization reaction, the polymerization temperature was adjusted to be 65° C. After a lapse of 12 hours, the unreacted portion of 1,3-butadiene was collected when the internal pressure reached 4.5 kg/cm.sup.2 (gage pressure). Subsequently, the internal temperature was changed to 80° C. and then holding was performed for 1 hour. Hereby, a butadiene rubber latex having a volume-average particle size of 250 nm and a solid content of 41% was prepared.

(62) Into a 5-liter glass reaction container, 20 parts of the butadiene rubber latex was charged in terms of solid content. Subsequently, 1.0 parts of dipotassium alkenylsuccinate and 150 parts of water were added to the container, which was then purged with nitrogen. Subsequently, the internal temperature was increased to 70° C. To the container, an aqueous solution prepared by dissolving 0.12 parts of potassium persulfate in 10 parts of water was added. Subsequently, a monomer mixture including 79.5 parts of n-butyl acrylate (Aa), 0.33 parts of allyl methacrylate, and 0.17 parts of 1,3-butylene glycol dimethacrylate, which had been purged with nitrogen, was continuously added dropwise to the container over 2 hours. After the completion of the addition of the monomer mixture, the internal temperature was increased to 80° C. and holding was performed for 1 hour. Hereby, an aqueous dispersion of a copolymer (A-II-16) that was constituted by a butadiene rubber and an acrylic rubber and had a volume-average particle size of 300 nm was prepared.

(63) Tables 4A and 4B summarize the degree of swelling and volume-average particle size of each of the copolymers (A-II-1) to (A-II-16).

(64) TABLE-US-00007 TABLE 4A Copolymer (A) A-II-1 A-II-2 A-II-3 A-II-4 A-II-5 A-II-6 A-II-7 A-II-8 Raw n-Butyl acrylate 54 48 48 51.6 49.2 48 48 48 material 2-Phenoxyethyl acrylate 6 12 12 8.4 10.8 12 12 12 composition Styrene (part) Butadiene rubber Dipotassium 0.20 1.50 0.11 0.20 0.20 0.20 0.20 0.20 alkenylsuccinate 1,3-Butylene glycol 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 dimethacrylate Allyl methacrylate 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 Degree of swelling (time) 6.2 6.1 6.3 6.3 6.2 6.2 6.2 6.1 Volume-average particle size (nm) 300 120 550 300 300 300 300 300 Remark For Examples

(65) TABLE-US-00008 TABLE 4B Copolymer (A) A-II-9 A-II-10 A-II-11 A-II-12 A-II-13 A-II-14 A-II-15 A-II-16 Raw n-Butyl acrylate 46.8 44.4 42 55.8 39 60 42 48 material 2-Phenoxyethyl acrylate 13.2 15.6 18 4.2 21 composition Styrene 12 (part) Butadiene rubber 12 Dipotassium 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.60 alkenylsuccinate 1,3-Butylene glycol 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.10 dimethacrylate Allyl methacrylate 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.20 Degree of swelling (time) 6.2 6.1 6.2 6.4 6.1 6.2 6.2 6.2 Volume-average particle size (nm) 300 300 300 300 300 300 300 300 Remark For Examples For Comparative examples

Preparation of Graft Copolymers (B)

Preparation of Graft Copolymer (B-II-1)

(66) After the preparation of the copolymer (A-II-1), while the internal temperature of the reaction container was maintained to be 75° C., relative to 60 parts (in terms of solid content) of the copolymer (A-II-1), an aqueous solution containing 0.001 parts of ferrous sulfate, 0.003 parts of a disodium ethylenediaminetetraacetate salt, 0.3 parts of Rongalite, and 5 parts of ion-exchange water was added to the container. Subsequently, an aqueous solution containing 0.65 parts of dipotassium alkenylsuccinate and 10 parts of ion-exchange water was added to the container. Subsequently, a mixture of 8 parts of methyl methacrylate, 8 parts of acrylonitrile, and 24 parts of styrene, which was used as a vinyl monomer mixture (m1), and 0.18 parts of t-butyl hydroperoxide were added dropwise to the container over 1 hour 30 minutes to cause graft polymerization.

(67) After the completion of the addition of the mixture, the internal temperature was maintained to be 75° C. for 10 minutes. Subsequently, cooling was performed. When the internal temperature reached 60° C., an aqueous solution prepared by dissolving 0.2 parts of an antioxidant (ANTAGE W500 produced by YOSHITOMI PHARMACEUTICAL INDUSTRIES, LTD.) and 0.2 parts of dipotassium alkenylsuccinate in 5 parts of ion-exchange water was added to the container. The aqueous dispersion obtained as a reaction product was solidified using an aqueous sulfuric acid solution, cleaned with water, and then dried. Hereby, a graft copolymer (B-II-1) was prepared. The graft copolymer (B-II-1) had a graft ratio of 40%.

Preparation of Graft Copolymers (B-II-2) to (B-II-16)

(68) Graft copolymers (B-II-2) to (B-II-16) were prepared as in the preparation of the graft copolymer (B-II-1), except that the type of the copolymer (A) used was changed as described in Tables 5A and 5B.

(69) Tables 5A and 5B describe the graft ratios of the graft copolymers (B-II-2) to (B-II-16).

(70) TABLE-US-00009 TABLE 5A Graft copolymer (B) B-II-1 B-II-2 B-II-3 B-II-4 B-II-5 B-II-6 B-II-7 B-II-8 Copolymer A-II-1 60 (A) (part) A-II-2 60 A-II-3 60 A-II-4 60 A-II-5 60 A-II-6 60 A-II-7 60 A-II-8 60 Vinyl monomer Methyl methacrylate 8 8 8 8 8 8 12 4 mixture (m1) Acrylonitrile 8 8 8 8 8 8 8 8 (part) Styrene 24 24 24 24 24 24 5 28 Graft ratio (%) 40 41 40 39 40 39 40 41 Remark Invention example

(71) TABLE-US-00010 TABLE 5B Graft copolymer (B) B-II-9 B-II-10 B-II-11 B-II-12 B-II-13 B-II-14 B-II-15 B-II-16 Copolymer A-II-9 60 (A) (part) A-II-10 60 A-II-11 60 A-II-12 60 A-II-13 60 A-II-14 60 A-II-15 60 A-II-16 60 Vinyl monomer Methyl methacrylate 8 8 8 8 8 8 8 8 mixture (m1) Acrylonitrile 8 8 8 8 8 8 8 8 (part) Styrene 24 24 24 24 24 24 24 24 Graft ratio (%) 40 40 41 40 40 40 40 40 Remark Invention example For Comparative examples

Examples II-1 to II-13 and Comparative Examples II-1 to II-3

(72) The components were mixed with each other in the amounts (mass parts) described in Tables 6A and 6B. The resulting mixture was further mixed with 0.8 parts of carbon black. The mixture was then melt-kneaded at 240° C. with a twin-screw extruder (“PCM30” produced by Ikegai Corp) having a vacuum vent with a diameter of 30 mm to form a pellet-like thermoplastic resin composition. The melt volume rate of the thermoplastic resin composition was determined by the above-described method. The transparency, impact resistance, and weather resistance of a molded article prepared by injection-molding of the thermoplastic resin composition were evaluated by the above-described methods.

(73) Tables 6A and 6B describe the evaluation results.

(74) TABLE-US-00011 TABLE 6A Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple ple ple ple ple ple II-1 II-2 II-3 II-4 II-5 II-6 II-7 II-8 II-9 II-10 II-11 II-12 II-13 Graft B-II-1 28 copolymer B-II-2 28 (B) (part) B-II-3 28 B-II-4 28 B-II-5 28 B-II-6 28 B-II-7 28 B-II-8 28 B-II-9 28 B-II-10 28 B-II-11 28 B-II-12 28 B-II-13 28 Copolymer C-1 72 72 72 72 72 72 72 72 72 72 72 72 72 (C)(part) Charpy impact strength 8.4 8.2 8.2 8.3 8.1 8.1 8.1 8.1 8.1 7.9 7.7 8.4 6.2 at 23° C. (kJ/m.sup.2) 220° C. MVR(cm.sup.3/ 12.9 13.0 13.1 13.1 13.2 13.1 11.2 14.1 12.4 12.9 12.8 12.9 13.1 10 min) Transparency (Hz) 6.9 1.5 1.5 4.7 1.5 1.5 3.1 3.9 1.5 4.9 6.9 12 13 Weather resistance 3.1 3.2 2.9 3.1 3.0 3.0 2.5 3.5 3.1 3.1 3.1 3.1 3.1 (ΔHz)

(75) TABLE-US-00012 TABLE 6B Comparative Comparative Comparative example II-1 example II-2 example II-3 Graft copolymer (B) B-II-14 28 (part) B-II-15 28 B-II-16 28 Copolymer (C)(part) C-1 72 72 72 Charpy impact strength at 8.2 3.8 7.8 23° C. (kJ/m.sup.2) 220° C. MVR(cm.sup.3/10 min) 13.2 12.9 12.1 Transparency (Hz) 95 19 35 Weather resistance (ΔHz) 3.2 10.0 28

(76) The results obtained in Examples II-1 to II-13 described in Table 6A confirm that, in Examples, a thermoplastic resin composition and a molded article that had excellent impact resistance, excellent flowability, excellent transparency, and excellent weather resistance were prepared.

(77) In contrast, as described in Table 6B, the resin compositions and the molded articles prepared in Comparative examples II-1 to II-3 were significantly poor in terms of any of impact resistance, flowability, transparency, and weather resistance.

(78) Although the present invention has been described in detail with reference to particular embodiments, it is apparent to a person skilled in the art that various modifications can be made therein without departing from the spirit and scope of the present invention.

(79) The present application is based on Japanese Patent Applications Nos. 2018-208252 and 2018-208253 filed on Nov. 5, 2018, which are incorporated herein by reference in their entirety.