JP2015189964A - thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition in which poor appearance caused by burned resin is suppressed, and also residence heat stability upon molding is excellent.SOLUTION: Provided is a thermoplastic resin composition in which the content of iron ions is 20 ppm or lower, and further, the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions is 100 to 4,000 ppm.

Description

The present invention relates to a thermoplastic resin composition in which poor appearance due to a baked resin is suppressed, and the residence heat stability during molding is excellent.

A thermoplastic resin composition containing a graft copolymer (for example, ABS resin, AES resin, ASA resin, etc.) obtained by graft polymerization of a monomer to a rubbery polymer is a resin having an excellent balance between impact resistance and processability. It is used in a wide range of fields such as interior and exterior parts for vehicles such as automobiles, housings for various home appliances and OA equipment, and other miscellaneous goods.

However, the rubbery polymer in the graft copolymer, in particular, undergoes thermal degradation due to heat applied in the powdering process, granulation process, molding process, etc., and causes the generation of a burned resin. When this burnt resin is present in the vicinity of the surface of the molded product or film, there is a problem that an appearance defect is caused. Therefore, there is a demand for a thermoplastic resin composition that suppresses the generation of a burnt resin due to thermal history and can provide a good surface appearance when processed into a molded product or film.

As a method for suppressing the generation of burnt resin, Patent Document 1 provides excellent fluidity and eliminates the pulsation of extruded molten strands by defining the range of the Q value of the rubber-modified thermoplastic resin composition. Further, it is disclosed that the occurrence of burning and foreign matters due to resin retention is suppressed. However, in this method, the generation of the burned resin in the granulation step is suppressed, but since the generation of the burnt resin other than the granulation step cannot be suppressed, it is still not fully satisfactory.

JP 10-17627 A

The present invention relates to a thermoplastic resin composition in which poor appearance due to a baked resin is suppressed, and the residence heat stability during molding is excellent.

As a result of intensive studies to solve the problems of the prior art, the present inventors have found that the iron ion content in the thermoplastic resin composition is 20 ppm or less, and further potassium ions, sodium ions, magnesium ions, calcium ions and sulfuric acid. The inventors have found that the above object can be achieved by setting the total content of ions to 100 to 4000 ppm, and have reached the present invention.

That is, the present invention provides a thermoplastic resin composition characterized in that the iron ion content is 20 ppm or less, and the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions is 100 to 4000 ppm. It is about.

According to the present invention, it is possible to obtain a thermoplastic resin composition in which the appearance defect due to the burned resin is suppressed and the residence heat stability during molding is excellent.

The present invention will be described in detail below.
In the present invention, the baked resin refers to a thermoplastic resin composition that is generated due to thermal deterioration due to heat applied in a powdering process, a granulating process, a molding process, and the like.

In the present invention, the retention thermal stability at the time of molding refers to the effect on the appearance of the molded product molded after the molten resin has retained in the cylinder for a long time. Usually, if the molten resin stays in the cylinder for a long time, the generation of the burned resin tends to increase, and the burnt resin causes poor appearance of the molded product.

The thermoplastic resin composition of the present invention preferably contains a graft copolymer.

Examples of the rubber-like polymer constituting the graft copolymer used in the present invention include polybutadiene rubber, styrene-butadiene rubber (SBR), styrene-butadiene-styrene (SBS) block copolymer, and styrene- (ethylene-butadiene) -styrene. (SEBS) block copolymer, conjugated diene polymer such as acrylonitrile-butadiene rubber (NBR), methyl methacrylate-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-nonconjugated diene (such as ethylidene norbornene, dicyclopentadiene) rubber, etc. Acrylic rubbers such as ethylene-propylene rubbers, polybutyl acrylate rubbers, silicone rubbers, and one or more composite rubbers selected from these rubbers can be used. One or two or more rubbers can be used. . In particular, a conjugated diene polymer is preferable.

The method for polymerizing the rubbery polymer is not particularly limited, and can be produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or a combination thereof, but the emulsion polymerization method is particularly preferable.

Emulsifiers used when obtaining rubbery polymers by emulsion polymerization include sulfate esters of higher alcohols, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, nonionic Nonionic surfactants such as anionic surfactants such as sulfate salts of surfactants or alkyl ester types, alkyl phenyl ether types, alkyl ether types of polyethylene glycol, etc. are used, and one or more of these are used. can do. In particular, alkylbenzene sulfonate and aliphatic carboxylate are preferable.

Polymerization initiators used for obtaining rubbery polymers by emulsion polymerization methods include water-soluble polymerization initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate, cumene hydroperoxide, benzoyl peroxide, and t-butyl hydro gen. Oil-soluble polymerization initiators such as peroxide, acetyl peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide can be used as appropriate. Redox initiators composed of a combination of these initiators and reducing agents can also be used. Examples of reducing agents include ferrous sulfate heptahydrate, sulfite, bisulfite, pyrosulfite, nitrite, nithion. Acid salts, thiosulfates, formaldehyde sulfonates, benzaldehyde sulfonates, carboxylic acids such as L-ascorbic acid, tartaric acid, citric acid, reducing sugars such as lactose, dextrose, saccharose, and dimethylaniline Examples include amines such as triethanolamine. Moreover, when using a redox-type initiator, tetrasodium pyrophosphate, disodium ethylenediaminetetraacetate (dihydrate), etc. are used as a chelating agent.

There is no particular limitation on the polymerization method for obtaining the rubbery polymer by the emulsion polymerization method, but batch polymerization, semi-batch polymerization, seed polymerization and the like can be used. Moreover, the addition method of various components is not particularly limited, and a batch addition method, a divided addition method, a continuous addition method, a power feed method, or the like can be used.

The polymerization temperature for obtaining the rubbery polymer by the emulsion polymerization method is not particularly limited, but is preferably 40 to 80 ° C.

Although there is no restriction | limiting in particular in the weight average particle diameter of a rubber-like polymer, 150-800 nm is preferable and 200-600 nm is more preferable from physical property balances, such as impact resistance, fluidity | liquidity, and coloring property. Moreover, it can also adjust by adding an acid to the rubber-like polymer whose weight average particle diameter is 50-300 nm, and making it cohesive enlargement.

The graft copolymer used in the present invention includes an aromatic vinyl monomer, a vinyl cyanide monomer, and other vinyl monomers copolymerizable therewith in the presence of the rubbery polymer described above. It is obtained by graft polymerization of at least one monomer selected from a monomer.

Examples of the aromatic vinyl monomer used for the graft polymerization include styrene, α-methylstyrene, paramethylstyrene, bromostyrene, and the like, and one or more of them can be used. In particular, styrene and α-methylstyrene are preferable.

Examples of the vinyl cyanide monomer used for the graft polymerization include acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile and the like, and one or more of them can be used. Particularly preferred is acrylonitrile.

Examples of other copolymerizable vinyl monomers used for graft polymerization include (meth) acrylic acid ester monomers, maleimide monomers, amide monomers, and the like, one or more Can be used. (Meth) acrylic acid ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl acrylate, (meth) acrylic Acid phenyl, (meth) acrylic acid 4-t-butylphenyl, (meth) acrylic acid (di) bromophenyl, (meth) acrylic acid chlorophenyl, and the like. As the maleimide monomer, N-phenylmaleimide, Examples thereof include N-cyclohexylmaleimide, and examples of the amide monomer include acrylamide and methacrylamide.

There is no particular limitation on the composition ratio of the above-mentioned monomer graft-polymerized on the rubber-like polymer, but aromatic vinyl monomer 60 to 90% by weight, vinyl cyanide monomer 10 to 40% by weight And a composition ratio of 0 to 30% by weight of another copolymerizable vinyl monomer, 30 to 80% by weight of an aromatic vinyl monomer, 20 to 70% by weight of a (meth) acrylate monomer and Composition ratio of 0 to 50% by weight of other copolymerizable monomers, 20 to 70% by weight of aromatic vinyl monomer, 20 to 70% by weight of (meth) acrylate monomer, cyan The composition ratio is preferably 10 to 60% by weight of a vinyl fluoride monomer and 0 to 30% by weight of another copolymerizable vinyl monomer (the total amount of monomers used for graft polymerization is 100% by weight). Part).

The content of the rubber-like polymer in the graft copolymer is preferably 20 to 85 parts by weight, and preferably 40 to 70 parts by weight, from the balance of physical properties such as impact resistance, fluidity and color developability. More preferable (the graft copolymer is 100 parts by weight). If the content of the rubbery polymer is less than 20 parts by weight, the graft ratio of the graft copolymer is increased and the impact resistance is inferior, and if it exceeds 85 parts by weight, the graft ratio of the graft copolymer is decreased and the color development is inferior. .

The polymerization method of the graft copolymer is not particularly limited, and can be produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or a combination thereof, but the emulsion polymerization method is particularly preferable.

As the emulsifier, the initiator, the polymerization method and the polymerization temperature used when the graft copolymer is obtained by the emulsion polymerization method, those similar to those used when the rubber-like polymer described above is obtained by the emulsion polymerization method can be used.

Graft rate of the graft copolymer (determined from the amount of acetone-soluble and insoluble components in the graft copolymer and the weight of the rubbery polymer in the graft copolymer), and the reduced viscosity of the acetone-soluble component (0.4 g / There is no particular limitation on the 100 cc, N, N dimethylformamide solution measured at 30 ° C., and any structure can be used depending on the required performance, but the balance of physical properties such as impact resistance, fluidity and color developability can be used. From the viewpoint, the graft ratio is preferably 25 to 150%, and the reduced viscosity is preferably 0.2 to 2.0 dl / g.

When the graft copolymer is obtained by an emulsion polymerization method, a powder can be obtained through steps of coagulation, washing, dehydration and drying. Examples of the coagulant used in the coagulation step include metal salts such as calcium chloride, magnesium chloride, magnesium sulfate, and aluminum sulfate, and inorganic acids and organic acids such as hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid. Two or more kinds can be used as an aqueous solution. Further, a recovery and drying method using a spray dryer or an atomizer can be used without using a coagulant.

The thermoplastic resin composition of the present invention contains one or more graft copolymers, and may further contain other resins. For example, polystyrene resin, styrene-acrylonitrile resin, α-methylstyrene-acrylonitrile resin, styrene-methyl methacrylate resin, styrene-acrylonitrile-methyl methacrylate resin, N-phenylmaleimide-styrene resin, N-phenylmaleimide-styrene-acrylonitrile resin, etc. Styrene resin; acrylic resin such as polymethyl methacrylate resin; polycarbonate resin; polyester resin such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyamide resin; biodegradable resin such as polylactic acid resin; polypropylene and polyethylene And olefin-based resins.

In the thermoplastic resin composition of the present invention, the graft copolymer is preferably contained so that the rubber-like polymer content in the thermoplastic resin composition is 5 to 50% by weight from the viewpoint of the balance of physical properties, More preferably, the content is 10 to 30% by weight.

As a method for reducing the iron ion content in the thermoplastic resin composition, for example, when the graft copolymer is obtained by an emulsion polymerization method, the amount of ferrous sulfate heptahydrate which is a reducing agent of a redox initiator is used. Reduction, change to other reducing agents, add a chelating agent to the polymerized latex to form a metal complex to increase water solubility, and when the obtained slurry is subjected to a high-speed centrifugal dehydrator, the amount of water washed It can adjust suitably by the method of passing the obtained powder, or passing the obtained powder through an iron remover.

As a method for adjusting the sodium ion and potassium ion content in the thermoplastic resin composition, for example, when the graft copolymer is obtained by an emulsion polymerization method, the use amount of the emulsifier is changed, and the fatty acid metal salt derived from the emulsifier is used. It can be appropriately adjusted by a method of returning to the fatty acid again and washing with a solvent, or a method of changing the amount of washing with water when the obtained slurry is subjected to a high-speed centrifugal dehydrator.

As a method for adjusting the content of magnesium ion, calcium ion and sulfate ion in the thermoplastic resin composition, for example, when the graft copolymer is obtained by an emulsion polymerization method, the amount of coagulant when changing the amount of powder from latex is changed. When the obtained powder is subjected to a high-speed centrifugal dehydrator, it can be appropriately adjusted by a method of changing the amount of washing.

The iron ion content in the thermoplastic resin composition of the present invention is 20 ppm or less, and the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions is 100 to 4000 ppm, and the iron ion content is 10 ppm. In the following, it is more preferable that the total content of potassium ion, sodium ion, magnesium ion, calcium ion and sulfate ion is 100 to 3000 ppm. By making the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions 100 to 4000 ppm, the iron ion content in the thermoplastic resin composition is 20 ppm or less. Thus, a thermoplastic resin composition having a good appearance of the molded product and having excellent residence heat stability during molding can be obtained.

The thermoplastic resin composition of the present invention is an antioxidant such as a hindered amine-based light stabilizer, a hindered phenol-based compound, a sulfur-containing organic compound-based compound, or a phosphorus-containing organic compound-based compound as long as it does not depart from the object of the present invention. , Heat stabilizers such as phenol-based and acrylate-based, benzoate-based, benzotriazole-based, benzophenone-based, salicylate-based UV absorbers, organic nickel-based, lubricants such as higher fatty acid amides, plasticizers such as phosphate esters, Flame retardants and flame retardants such as polybromophenyl ether, tetrabromobisphenol-A, brominated epoxy oligomers, halogenated compounds such as bromination, phosphorus compounds, antimony trioxide, odor masking agents, carbon black, oxidation Titanium, pigments, dyes, and the like can also be added. Furthermore, reinforcing agents and fillers such as talc, calcium carbonate, aluminum hydroxide, glass fiber, glass flake, glass bead, carbon fiber, and metal fiber can be added.

The thermoplastic resin composition of the present invention can be obtained by mixing the above-described components. In order to mix, well-known kneading apparatuses, such as an extruder, a roll, a Banbury mixer, a kneader, can be used, for example.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” are based on weight.

Manufacture of small particle size styrene-butadiene rubber latex After replacing the inside of a 10 liter pressure vessel with nitrogen, 95 parts by weight of 1,3-butadiene, 5 parts by weight of styrene, 0.23 parts by weight of n-dodecyl mercaptan, potassium persulfate 0.29 parts by weight, disproportionated sodium rosinate 1.98 parts by weight (solid content), sodium hydroxide 0.05 parts by weight (solid content), 158 parts by weight of deionized water were charged at 69 ° C. with stirring. The reaction was allowed for 8 hours. Thereafter, 0.24 parts by weight (sodium content) of disproportionated sodium rosinate, 0.08 parts by weight (solid content) of sodium hydroxide and 7 parts by weight of deionized water were added. Further, stirring was continued for 5 hours while maintaining the temperature at 69 ° C. to complete the reaction. Thereafter, the remaining 1,3-butadiene was removed under reduced pressure to obtain a small particle size styrene-butadiene rubber latex. The obtained small particle size styrene-butadiene rubber latex was dyed with osmium tetroxide (OsO ₄ ), dried and photographed with a transmission electron microscope. As a result of measuring the area of 800 rubber particles using an image analysis processing device (device name: IP-1000PC manufactured by Asahi Kasei Co., Ltd.), obtaining the equivalent circle diameter (diameter), and calculating the weight average particle diameter, It was 99 nm.

Production of agglomerated styrene-butadiene rubber latex (a-1) In a 10 liter pressure vessel, 177 parts by weight of deionized water, 100 parts by weight of a small particle size styrene-butadiene rubber latex (solid content), sodium dodecylbenzenesulfonate After adding 0.022 parts by weight (solid content) and stirring and mixing for 8 minutes, 18 parts by weight of 5% aqueous phosphoric acid solution was added over 8 minutes. Subsequently, 9 weight part of 10% potassium hydroxide aqueous solution was added, and the agglomerated enlarged styrene-butadiene rubber latex (a-1) was obtained.
It was 425 nm as a result of calculating the weight average particle diameter of a cohesive enlarged styrene-butadiene rubber (a-1) with the above-mentioned method.

Production of agglomerated styrene-butadiene rubber latex (a-2) In a 10-liter pressure vessel, 192 parts by weight of deionized water, 100 parts by weight of small particle size styrene-butadiene rubber latex (solid content), sodium dodecylbenzenesulfonate After adding 0.052 parts by weight (solid content) and stirring and mixing for 8 minutes, 18 parts by weight of 5% aqueous phosphoric acid solution was added over 7 minutes. Subsequently, 9 weight part of 10% potassium hydroxide aqueous solution was added, and the agglomerated enlarged styrene-butadiene rubber latex (a-2) was obtained.
It was 267 nm as a result of calculating the weight average particle diameter of the aggregation-enlarged styrene-butadiene rubber (a-2) by the above-mentioned method.

Production of Styrene-Butadiene Rubber Latex (a-3) After replacing the inside of a 10-liter pressure vessel with nitrogen, 95 parts by weight of 1,3-butadiene, 5 parts by weight of styrene, 0.25 parts by weight of n-dodecyl mercaptan, excess 653 parts by weight of potassium sulfate, 0.25 part by weight of disproportionated sodium rosinate (solid content), 0.12 part by weight of sodium hydroxide (solid content) and 67 parts by weight of deionized water were added and stirred while stirring. The reaction was carried out at ° C. Disproportionated sodium rosinate 0.33 parts by weight (solid content), sodium hydroxide 0.11 parts by weight (solid content) and deionized water 7 at 11 hours, 22 hours, 33 hours and 44 hours, respectively .7 parts by weight was added and reacted for 51 hours. Thereafter, 0.19 parts by weight (sodium content) of disproportionated sodium rosinate, 0.1 parts by weight (solid content) of sodium hydroxide and 4 parts by weight of deionized water were added. Further, stirring was continued for 8 hours while maintaining the temperature at 70 ° C. to complete the reaction. Thereafter, the remaining 1,3-butadiene was removed under reduced pressure to obtain a styrene-butadiene rubber latex (a-3). It was 435 nm as a result of calculating a weight average particle diameter with the above-mentioned method.

Production of graft copolymer (A-1) A glass reactor was charged with 50 parts by weight (solid content) of agglomerated and enlarged styrene-butadiene rubber latex (a-1), followed by nitrogen substitution. After nitrogen substitution, when the temperature inside the tank reached 62.5 ° C., 0.5 parts by weight of acrylonitrile, 5.5 parts by weight of styrene and 0.2 parts by weight of lactose, 0.1 part by weight of tetrasodium pyrophosphate and An aqueous solution in which 0.007 parts by weight of ferrous sulfate heptahydrate was dissolved in 17 parts by weight of deionized water was added. After reaching 70 ° C., 1.1 parts by weight of potassium oleate (solid content) in a mixture of 12.0 parts by weight of acrylonitrile, 32 parts by weight of styrene, 0.07 parts by weight of tarsia decyl mercaptan and 20 parts by weight of deionized water An aqueous emulsifier solution in which 0.13 parts by weight (solid content) of t-butyl hydroperoxide was dissolved was continuously added dropwise over 4.5 hours. After the dropping, the mixture was maintained for 3.3 hours to obtain a graft copolymer latex (A-1). Thereafter, 0.1 part of disodium ethylenediaminetetraacetate (dihydrate), which is a chelating agent, was added, followed by dehydration and drying with the number of coagulants, washing water amount and centrifugal dehydration shown in Table 1, and the graft polymer (A- The powder of 1) was obtained.

Production of graft copolymer (A-2) A glass reactor was charged with 40 parts by weight (solid content) of coagulated and enlarged styrene-butadiene rubber latex (a-1), followed by nitrogen substitution. After nitrogen substitution, when the temperature in the tank was raised to 66 ° C., 1.0 part by weight of acrylonitrile and 6.0 parts by weight of styrene were added. After reaching 70 ° C., 0.23 part of sodium persulfate was added, and 0.82 part by weight of potassium oleate (solid content) was dissolved in 17.0 parts by weight of acrylonitrile, 36 parts by weight of styrene, and 20 parts by weight of deionized water. The emulsifier aqueous solution was continuously added dropwise over 3.3 hours. After dripping, it was kept for 4.2 hours to obtain a graft copolymer latex (A-2). Thereafter, the solidifying agent shown in Table 1, the amount of washing water, and the number of centrifugal dehydration were dehydrated and dried, and the iron content in the powder was removed using an iron remover to obtain a graft polymer (A-2) powder. .

Production of graft copolymer (A-3) A glass reactor was charged with 60 parts by weight (solid content) of agglomerated and enlarged styrene-butadiene rubber latex (a-1), followed by nitrogen substitution. After nitrogen substitution, when the temperature inside the tank reached 60 ° C., 3 parts by weight of styrene, 0.22 parts by weight of lactose, 0.11 part by weight of tetrasodium pyrophosphate and 0.021 weight of ferrous sulfate heptahydrate An aqueous solution having a part dissolved in 14 parts by weight of deionized water was added. After reaching 69 ° C., 0.95 parts by weight of potassium oleate (solid content) in a mixture of 12.0 parts by weight of acrylonitrile, 25 parts by weight of styrene, 0.13 parts by weight of terrestrial decyl mercaptan and 17 parts by weight of deionized water An aqueous emulsifier solution in which 0.22 parts by weight (solid content) of t-butyl hydroperoxide was dissolved was continuously added dropwise over 3.7 hours. After dropping, the mixture was held for 2.9 hours to obtain a graft copolymer latex (A-3). Thereafter, 0.05 part of disodium ethylenediaminetetraacetate (dihydrate) as a chelating agent was added, followed by dehydration and drying with the coagulant, washing water amount, and centrifugal dehydration number shown in Table 1, and the graft polymer (A- The powder of 3) was obtained.

Production of graft copolymer (A-4) A glass reactor was charged with 50 parts by weight (solid content) of coagulated and enlarged styrene-butadiene rubber latex (a-1), and nitrogen substitution was performed. After nitrogen substitution, when the temperature in the tank was increased to 63.5 ° C., 5 parts by weight of styrene, 0.18 part by weight of lactose, 0.05 part by weight of tetrasodium pyrophosphate, and ferrous sulfate heptahydrate An aqueous solution having 013 parts by weight dissolved in 15 parts by weight of deionized water was added. After reaching 70 ° C., 1.25 parts by weight of potassium oleate (solid content) in a mixed solution of 15 parts by weight of acrylonitrile, 30 parts by weight of styrene, 0.22 parts by weight of tertiary decyl mercaptan and 15 parts by weight of deionized water, t -An aqueous emulsifier solution in which 0.32 parts by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 4.25 hours. After the dropping, the mixture was held for 3.2 hours to obtain a graft copolymer latex (A-4). Thereafter, 0.1 part of disodium ethylenediaminetetraacetate (dihydrate), which is a chelating agent, was added, followed by dehydration and drying with the number of coagulants, washing water amount and centrifugal dehydration shown in Table 1, and the graft polymer (A- The powder of 4) was obtained.

Production of graft copolymer (A-5) A glass reactor was charged with 50 parts by weight (solid content) of agglomerated and enlarged styrene-butadiene rubber latex (a-2) and purged with nitrogen. After nitrogen substitution, when the temperature inside the tank reached 60 ° C., 6 parts by weight of styrene, 0.25 parts by weight of lactose, 0.09 parts by weight of tetrasodium pyrophosphate and 0.012 parts by weight of ferrous sulfate heptahydrate An aqueous solution having a part dissolved in 16 parts by weight of deionized water was added. After reaching 70 ° C., 1.05 parts by weight (solid content) of potassium oleate in a mixed solution of 15 parts by weight of acrylonitrile, 29 parts by weight of styrene, 0.25 parts by weight of terrestrial decyl mercaptan and 16 parts by weight of deionized water, t -An aqueous emulsifier solution in which 0.39 parts by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 4.0 hours. After dripping, the copolymer was retained for 4.0 hours to obtain a graft copolymer latex (A-5). Thereafter, after adding 0.001 part of ethylenediaminetetraacetic acid disodium (dihydrate), which is a chelating agent, dehydration and drying were performed using the coagulant, washing water amount, and centrifugal dehydration number shown in Table 1, and the graft polymer (A- The powder of 5) was obtained.

Production of graft copolymer (A-6) A glass reactor was charged with 50 parts by weight (solid content) of styrene-butadiene rubber latex (a-3) and purged with nitrogen. After nitrogen substitution, when the temperature inside the tank reached 66 ° C., 5 parts by weight of styrene, 0.31 part by weight of lactose, 0.14 part by weight of tetrasodium pyrophosphate and 0.019 part by weight of ferrous sulfate heptahydrate An aqueous solution in which a part was dissolved in 17 parts by weight of deionized water was added. After reaching 71 ° C., 1.15 parts by weight of potassium oleate (solid) in a mixture of 12.5 parts by weight of acrylonitrile, 32.5 parts by weight of styrene, 0.14 parts by weight of terrestrial decyl mercaptan and 18 parts by weight of deionized water Min), an aqueous emulsifier solution in which 0.25 parts by weight (solid content) of t-butyl hydroperoxide was dissolved was continuously added dropwise over 4.5 hours. After the dropping, the mixture was held for 3.5 hours to obtain a graft copolymer latex (A-6). Then, it dehydrated and dried by the coagulant | flocculant shown in Table 1, the amount of washing water, and the frequency | count of centrifugal dehydration, and obtained the powder of the graft polymer (A-6).

Production of graft copolymer (A-7) A glass reactor was charged with 40 parts by weight (solid content) of styrene-butadiene rubber latex (a-3) and purged with nitrogen. After nitrogen substitution, when the temperature inside the tank reached 67 ° C., 3 parts by weight of styrene, 0.29 parts by weight of lactose, 0.11 part by weight of tetrasodium pyrophosphate and 0.099 weight of ferrous sulfate heptahydrate An aqueous solution having a part dissolved in 16 parts by weight of deionized water was added. After reaching 70 ° C., 15 parts by weight of acrylonitrile, 42 parts by weight of styrene, 0.18 parts by weight of terrestrial decyl mercaptan and 18 parts by weight of deionized water were added to 1.0 part by weight of potassium oleate (solid content), t -An aqueous emulsifier solution in which 0.27 part by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 5.5 hours. After dripping, the copolymer was retained for 4.2 hours to obtain a graft copolymer latex (A-7). Then, it dehydrated and dried with the coagulant | flocculant shown in Table 1, the amount of washing water, and the frequency | count of centrifugal dehydration, and obtained the powder of the graft polymer (A-7).

Production of graft copolymer (A-8) A glass reactor was charged with 60 parts by weight (solid content) of styrene-butadiene rubber latex (a-3) and purged with nitrogen. After nitrogen substitution, when the temperature in the tank reached 67 ° C., 8 parts by weight of styrene, 0.25 parts by weight of lactose, 0.12 parts by weight of tetrasodium pyrophosphate and 0.021 weight of ferrous sulfate heptahydrate An aqueous solution in which a part was dissolved in 17 parts by weight of deionized water was added. After reaching 70 ° C., a mixture of 12 parts by weight of acrylonitrile, 20 parts by weight of styrene, 0.17 part by weight of tarlead decyl mercaptan and 17 parts by weight of deionized water, 1.0 part by weight of potassium oleate (solid content), t -An aqueous emulsifier solution in which 0.31 part by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 5.0 hours. After dripping, it was kept for 4.0 hours to obtain a graft copolymer latex (A-8). Then, it dehydrated and dried with the coagulant | flocculant shown in Table 1, the amount of washing water, and the frequency | count of centrifugal dehydration, and the powder of the graft polymer (A-8) was obtained.

Production of graft copolymer (A-9) A glass reactor was charged with 40 parts by weight (solid content) of coagulated and enlarged styrene-butadiene rubber latex (a-2), and nitrogen substitution was performed. After nitrogen substitution, when the temperature inside the tank reached 65 ° C, 5 parts by weight of styrene, 0.21 parts by weight of lactose, 0.15 parts by weight of tetrasodium pyrophosphate and 0.018 parts by weight of ferrous sulfate heptahydrate An aqueous solution having a part dissolved in 15 parts by weight of deionized water was added. After reaching 68 ° C., a mixture of 15 parts by weight of acrylonitrile, 40 parts by weight of styrene, 0.23 parts by weight of tarlead decyl mercaptan and 15 parts by weight of deionized water, 1.0 part by weight of potassium oleate (solid content), t -An aqueous emulsifier solution in which 0.33 parts by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 6.0 hours. After dripping, it was kept for 3.5 hours to obtain a graft copolymer latex (A-9). Then, it dehydrated and dried with the coagulant | flocculant shown in Table 1, the amount of washing water, and the frequency | count of centrifugal dehydration, and obtained the powder of the graft polymer (A-9).

Production of graft copolymer (A-10) A glass reactor was charged with 60 parts by weight (solid content) of agglomerated and enlarged styrene-butadiene rubber latex (a-2), followed by nitrogen substitution. After nitrogen substitution, when the temperature in the tank was increased to 65 ° C., 5 parts by weight of styrene, 0.21 part by weight of lactose, 0.15 part by weight of tetrasodium pyrophosphate, 0.2 part by weight of potassium persulfate and sulfuric acid An aqueous solution in which 0.034 parts by weight of ferrous heptahydrate was dissolved in 15 parts by weight of deionized water was added. After reaching 69 ° C., a mixture of 12 parts by weight of acrylonitrile, 23 parts by weight of styrene, 0.18 parts by weight of terrestrial decyl mercaptan and 15 parts by weight of deionized water, 1.1 parts by weight of potassium oleate (solid content), t An aqueous emulsifier solution in which 0.24 parts by weight (solid content) of butyl hydroperoxide was dissolved was continuously added dropwise over 3.8 hours. After the dropping, the mixture was maintained for 3.5 hours to obtain a graft copolymer latex (A-10). Then, it dehydrated and dried by the coagulant | flocculant shown in Table 1, the amount of washing water, and the frequency | count of centrifugal dehydration, and obtained the powder of the graft polymer (A-10).

Copolymer (B)
A styrene-acrylonitrile copolymer (B) comprising 70 parts of styrene and 30 parts of acrylonitrile was obtained by a known bulk polymerization method. The copolymer (B) had an iron ion, potassium ion, sodium ion, magnesium ion, calcium ion and sulfate ion content of 0 ppm.

Table 1

<Examples 1-5 and Comparative Examples 1-5>
After mixing the graft copolymer (A) and copolymer (B) shown in Table 2, Examples 1-5 and Comparative Examples were melt kneaded at 240 ° C. using a Toshiba TEM-35B twin screw extruder. 1-5 pellets were obtained. The pellets obtained in each Example and Comparative Example were used for the following analysis and evaluation. The results are shown in Table 2.

Method for quantifying iron ion After ashing the sample and dissolving the acid, iron was quantified by ICP emission spectroscopy.

Method for quantifying potassium ion, sodium ion, magnesium ion and calcium ion After ashing the sample and dissolving the acid, potassium ion, sodium ion, magnesium ion and calcium ion were quantified by flame atomic absorption spectrometry.

Sulfate ion quantification method Samples were extracted with pressurized hot water and sulfate ions were quantified by ion chromatography.

Appearance evaluation 70 to 90 g of the pellets, which had been sufficiently dried, were sandwiched between two stainless plates and placed in a hot press machine heated to 230 ° C., and the hot plate of the hot press machine was applied to the extent that no pressure was applied. Preheat for 6 minutes. After the preheating is completed, the press pressure is increased to 9.8 MPa, the molten resin protruding from between the stainless steel plates is grasped by hand, and drawn out to about 1 m into a film shape so that it does not slowly break (the thickness of the film is about 0.01 to 0). .10 mm).
Three circles having a diameter of 10 cm are drawn on the film, the number of burnt resin in each circle is counted (thickness of about 0.2 mm or more), and an average value is used.
A: 0 to 5 ○: 6 to 10 Δ: 11 to 20 ×: 21 or more

Measurement of oxidation heat generation start temperature The oxidation heat generation start temperature was measured using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Tech Science Co., Ltd.).
A higher oxidation heat generation start temperature suppresses the generation of a baked resin and is excellent in stagnant heat stability.
A: 220 ° C. or higher ○: 210 ° C. or higher and lower than 220 ° C. Δ: 200 ° C. or higher and lower than 210 ° C. x: Less than 200 ° C.

Table 2

As shown in Table 2, Examples 1 to 5 are examples of the thermoplastic resin composition of the present invention, which has a high oxidation heat generation start temperature, which is an index of generation of burnt resin and stagnant heat stability. There was also little and it was the favorable external appearance.

As shown in Table 2, Comparative Example 1 has a higher iron ion content in the thermoplastic resin composition than the prescribed amount of the present invention, and Comparative Example 2 has a higher iron ion content than Comparative Example 1. In Comparative Example 3, the total content of ions other than iron ions is less than the lower limit of the specified amount of the present invention, and in Comparative Example 4, the total content of ions other than iron ions is higher than the upper limit of the specified amount of the present invention. In Comparative Example 5, the iron ion content is greater than the specified amount of the present invention, and the total content of ions other than iron ions is greater than the upper limit of the specified amount of the present invention. For this reason, the oxidation heat generation start temperature, which is an index of generation of burnt resin and stagnant heat stability, is low, and there are many generations of burnt resin, resulting in poor appearance.

Since the thermoplastic resin composition of the present invention provides a good molded product appearance in which poor appearance due to the burnt resin is suppressed, the interior and exterior parts for vehicles such as automobiles, housings of various home appliances and OA equipment, It can be used in a wide range of other miscellaneous goods fields.

That is, the present invention provides a thermoplastic resin composition characterized in that the iron ion content is 20 ppm or less, and the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions is 100 to 4000 ppm. The rubber-like polymer relates to a thermoplastic resin composition containing a graft copolymer containing a conjugated diene polymer .

Claims (4)

A thermoplastic resin composition having an iron ion content of 20 ppm or less and a total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions of 100 to 4000 ppm. A thermoplastic resin composition, wherein the iron ion content is 10 ppm or less, and the total content of potassium ions, sodium ions, magnesium ions, calcium ions and sulfate ions is 100 to 4000 ppm. The thermoplastic resin composition according to claim 1, wherein a graft copolymer is contained. 4. The thermoplastic resin composition according to claim 3, wherein the rubbery polymer used for the graft copolymer is a conjugated diene polymer.