Resin composition

Abstract

[Problem] To provide a resin composition which is excellent in various physical properties and does not readily cause mold contamination during molding. [Solution] One embodiment of the present invention provides a resin composition containing an acrylonitrile-butadiene-styrene copolymer (ABS resin) and glycerin, wherein the glycerin content in the resin composition is less than 100 ppm.

Description

resin composition

[0001] This invention relates to a resin composition.

[0002] Acrylonitrile-butadiene-styrene copolymer (ABS resin) is used in a wide range of applications due to its excellent impact resistance and moldability (see Patent Document 1). However, depending on storage conditions, external environment, etc., mold contamination may occur during the molding of ABS resin.

[0003] Japanese Patent Application Publication No. 09-110943

[0004] In view of the above circumstances, the present invention aims to provide a resin composition that is excellent in various physical properties and less prone to mold contamination during molding.

[0005] According to one aspect of the present invention, a resin composition is provided which contains an acrylonitrile-butadiene-styrene copolymer (ABS resin) and glycerin, wherein the glycerin content in the resin composition is less than 100 ppm.

[0006] According to this embodiment, it is possible to provide a resin composition that has excellent physical properties and is less prone to mold contamination during molding.

[0007] <Resin Composition> The resin composition of this embodiment contains an acrylonitrile-butadiene-styrene copolymer (ABS resin). <<ABS Resin>> ABS resin is a general term for resins obtained by copolymerizing acrylonitrile, butadiene, and styrene as raw material monomers, and the ratio of each component can be set arbitrarily. In addition to or in place of styrene, monomers such as α-methylstyrene, vinyltoluene, dimethylstyrene, chlorostyrene, and vinylnaphthalene can be used as raw material monomers. In addition to or in place of acrylonitrile, monomers such as methacrylonitrile, ethacrylonitrile, and fumaronitrile can be used.

[0008] Furthermore, in addition to or instead of butadiene, monomers such as acrylic rubber mainly composed of (meth)acrylate, chlorinated polyethylene, and ethylene-propylene-diene rubber (EPDM), which is an ethylene-based rubber, can be used. In addition to acrylonitrile, butadiene, and styrene, other monomers can be used as raw material monomers. Examples of these other monomers include (meth)acrylic acid esters such as methyl methacrylate. Therefore, in this specification, ABS resin is a concept that includes not only acrylonitrile-butadiene-styrene copolymer (ABS resin), but also acrylonitrile-ethylene-propylene-diene-styrene copolymer (AES resin), acrylonitrile-styrene-acrylic acid ester copolymer (ASA resin), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS resin), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS resin: transparent ABS resin), etc.

[0009] Any resin can be used as the ABS resin as long as it has ABS resin as its main component. For example, ABS resin blends and ABS resin alloys can be used. Examples of resins with ABS resin as the main component include PC / ABS resin blends, which are made by blending polycarbonate (PC) and ABS resin. Furthermore, to improve the heat resistance of the ABS resin and the compatibility of PC / ABS resin blends and polyamide / ABS resin blends, for example, styrene-N-phenylmaleimide-maleic anhydride copolymers may be blended into them.

[0010] Furthermore, the resin composition of this embodiment contains glycerin (glycerol) in addition to the ABS resin, and the glycerin content in the resin composition is less than 100 ppm. In this specification, the content of X in Y (mass% or ppm) refers to the proportion of X when the total Y is considered to be 100% by mass. <<Glycerin>> As described above, mold contamination may occur when molding ABS resin depending on storage conditions, external environmental conditions, etc. The inventors diligently studied to resolve this problem and found that the glycerin content in the resin composition containing ABS resin has a significant influence. If the glycerin content in the resin composition is 100 ppm or more, mold contamination occurs frequently when molding the resin composition, regardless of storage conditions, external environmental conditions, etc. Therefore, the glycerin content in the resin composition was adjusted to less than 100 ppm.

[0011] Here, glycerin is a component that is introduced into the resin composition along with fatty acids or their salts used as emulsifiers when ABS resins are manufactured by emulsion polymerization, for example. From the viewpoint of preventing mold contamination during molding of the resin composition, it is preferable to keep the glycerin content in the resin composition as low as possible. To achieve this, it is effective to strongly heat the resin composition during the manufacturing process to volatilize the glycerin. However, in this case, the color of the resin composition may deteriorate due to the thermal history, or the mechanical strength of the molded product obtained from the resin composition may decrease. For this reason, it is not practical to have a glycerin content of 0 ppm in the resin composition, and it is preferable to leave a small amount of glycerin in the resin composition. Further investigation by the inventors has revealed that, unexpectedly, leaving a small amount of glycerin in the resin composition improves the fluidity of the resin composition and improves its moldability.

[0012] For these reasons, the glycerin content in the resin composition is preferably 0.1 ppm or more and less than 100 ppm, more preferably 0.1 ppm or more and 80 ppm or less, even more preferably 0.5 ppm or more and 60 ppm or less, particularly preferably 1 ppm or more and 40 ppm or less, and most preferably 1.5 ppm or more and 20 ppm or less. A resin composition containing glycerin within the above range can effectively prevent mold contamination during molding while improving mold processability. The glycerin content in the resin composition can be adjusted by setting manufacturing conditions in the ABS resin manufacturing process as described later, or by adding glycerin separately to the resin composition.

[0013] <Method for Producing Resin Composition> The resin composition of this embodiment can be produced, for example, as follows. First, a rubbery polymer latex is obtained by emulsion polymerization. Next, monomers such as vinyl cyanide monomers and aromatic vinyl monomers are added to this latex all at once, in batches, or sequentially to carry out emulsion graft polymerization on the rubbery polymer to obtain a graft copolymer (A) latex. Next, the graft copolymer (A) is precipitated (salted out) from this latex and recovered. After that, the graft copolymer (A) is mixed with a copolymer (B) of monomers such as vinyl cyanide monomers and aromatic vinyl monomers.

[0014] <<Graft Copolymer (A)>> Examples of rubbery polymers included in graft copolymer (A) include polymers of conjugated diene monomers such as butadiene, isoprene, dimethylbutadiene, chloroprene, and cyclopentadiene; polymers of unconjugated diene monomers such as 2,5-norbornadiene, 4-ethylidenenorbornene, and 1,4-cyclohexadiene; and optionally, copolymers exhibiting rubbery elasticity obtained by copolymerizing aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; acrylic acid ester monomers such as methyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate; methacrylic acid ester monomers such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; and olefin monomers such as ethylene, propylene, 1-butene, isobutylene, and 2-butene. In one embodiment, the rubbery polymer is preferably polybutadiene.

[0015] By using emulsion polymerization to prepare rubbery polymers, the particle size, particle size distribution, and other properties can be precisely controlled. In this emulsion polymerization, various surfactants such as anionic surfactants, nonionic surfactants, and amphoteric surfactants can be used as emulsifiers, and fatty acids or their salts (preferably higher fatty acids or their salts) can also be used. That is, the resulting resin composition may further contain fatty acids or their salts. Anionic surfactants include carboxylic acid type compounds and sulfate ester type compounds, and specific examples include alkali metal salts of rosinic acid, alkyl sulfonates with 8 to 20 carbon atoms, alkylaryl sulfates, and condensates of sodium naphthalene sulfonate and formaldehyde.

[0016] Specific examples of nonionic surfactants include, for example, polyvinyl alcohol or its copolymer (e.g., copolymer with acrylamide), polyvinyl ether or its copolymer (e.g., copolymer with maleic acid), polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, etc. Specific examples of amphoteric surfactants include, for example, lauryldimethylaminoacetic acid betaine, lauramidopropyl betaine, hydroxyalkyl (12 to 14 carbon atoms) hydroxyethyl sarcosine, lauramidopropyl hydroxysulfobetaine, sodium cocoamphodiacetate, sodium lauraminopropionate, lauryldimethylamine oxide, N-[3-alkyl(12,14)oxy-2-hydroxypropyl]-L-arginine hydrochloride, etc.

[0017] Examples of fatty acids (higher fatty acids) or salts thereof include a first higher fatty acid or salt thereof having 12 to 14 carbon atoms, a second higher fatty acid or salt thereof having 16 to 18 carbon atoms, or mixtures thereof. That is, it is preferable that the fatty acid or salt thereof contains at least one of a first higher fatty acid or salt thereof having 12 to 14 carbon atoms and a second higher fatty acid or salt thereof having 16 to 18 carbon atoms. The first higher fatty acid or salt thereof is considered to be a component that affects, for example, the fluidity (melt mass flow rate: MFR) and heat resistance (mass loss temperature) of the resulting resin composition. The first higher fatty acid may be either a saturated or unsaturated fatty acid, but a saturated fatty acid is preferred. Examples of salts of the first higher fatty acid include alkali metal salts, ammonium salts, lower amine salts, etc. Among these, alkali metal salts are preferred as the salt of the first higher fatty acid, and sodium salts or potassium salts are more preferred. Furthermore, the first higher fatty acid or salt thereof may be either anhydrous or hydrated. The first higher fatty acid or its salt is preferably at least one selected from lauric acid (dodecanoic acid), tridecanoic acid, myristic acid (tetradecanoic acid), and their salts, and more preferably at least one selected from lauric acid, myristic acid, and their salts.

[0018] The content of the first higher fatty acid or its salt in the resin composition is preferably less than 5000 ppm (10 ppm or more and less than 5000 ppm), more preferably 50 ppm or more and 4000 ppm or less, even more preferably 100 ppm or more and 3000 ppm or less, particularly preferably 300 ppm or more and 2000 ppm or less, and most preferably 500 ppm or more and 1000 ppm or less. In this case, the fluidity and heat resistance of the resin composition are easily improved. Hereinafter in this specification, when the higher fatty acid is a salt or hydrate, the content of the higher fatty acid or its salt shall be the value converted to the higher fatty acid as a free acid. Also in this specification, unless otherwise specified, the content of each higher fatty acid or its salt refers to the proportion of each higher fatty acid or its salt to the whole resin composition.

[0019] The second higher fatty acid or its salt is considered to be a component that affects, for example, the fluidity and moldability (mold fouling) of the resulting resin composition. The second higher fatty acid may be either a saturated or unsaturated fatty acid. Examples of salts of the second higher fatty acid include alkali metal salts, ammonium salts, and lower amine salts. Among these, alkali metal salts are preferred as the salt of the second higher fatty acid, and sodium salts or potassium salts are more preferred. The second higher fatty acid or its salt may be either an anhydrous or a hydrated form. As such a second higher fatty acid or its salt, at least one selected from palmitic acid, stearic acid, palmitoleic acid (hexadecenoic acid), oleic acid (octadecenoic acid), linoleic acid, linolenic acid and their salts is preferred, and at least one selected from palmitic acid, stearic acid, oleic acid, linoleic acid and their salts is more preferred.

[0020] The content of the second higher fatty acid or its salt is preferably less than 12,000 ppm, more preferably 500 ppm to 10,000 ppm, even more preferably 1,000 ppm to 8,000 ppm, particularly preferably 1,500 ppm to 6,000 ppm, and most preferably 2,000 ppm to 4,000 ppm. In this case, the fluidity and moldability of the resin composition are easily improved. The second higher fatty acid or its salt preferably contains linoleic acid or its salt. Including linoleic acid or its salt can further improve the moldability of the resin composition. Furthermore, the first higher fatty acid or its salt preferably contains myristic acid or its salt. Including myristic acid or its salt can further improve the heat resistance of the resin composition. That is, the first higher fatty acid or its salt preferably contains myristic acid or its salt, and the second higher fatty acid or its salt preferably contains linoleic acid or its salt.

[0021] The first higher fatty acid or its salt and the second higher fatty acid or its salt may include animal-derived higher fatty acids or their salts, but it is preferable that they include plant-derived higher fatty acids or their salts. By using plant-derived higher fatty acids or their salts, carbon dioxide emissions can be reduced, thereby lowering the environmental burden. Whether or not the first higher fatty acid or its salt and the second higher fatty acid or its salt include plant-derived higher fatty acids or their salts, and / or their content, is specified in ASTM D6866. １４ This can be determined by measuring the biomass content using the 1C isotope assay method.

[0022] Furthermore, the plant-derived higher fatty acids or salts thereof preferably include higher fatty acids or salts thereof prepared from at least one vegetable oil such as palm oil, palm olein, palm kernel oil, olive oil, rapeseed oil, sesame oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, rice bran oil, corn oil, coconut oil, and linseed oil, and more preferably include higher fatty acids or salts thereof prepared from at least one vegetable oil such as palm oil, palm olein, and palm kernel oil. Specifically, plant-derived higher fatty acids or salts thereof can be obtained by appropriately mixing higher fatty acids or salts thereof prepared from two or more vegetable oils, or by adding a desired higher fatty acid or salt thereof to a higher fatty acid or salt thereof prepared from at least one vegetable oil. By using such a first higher fatty acid or salt thereof and a second higher fatty acid or salt thereof, it is easy to adjust the type and content of higher fatty acids or salts thereof contained in the resin composition to the desired range.

[0023] The volume-average particle diameter of the rubbery polymer is preferably between 250 nm and 400 nm, and more preferably between 300 nm and 500 nm. Furthermore, multiple types of rubbery polymers with different average particle diameters may be mixed and used. Such a rubbery polymer can be produced by first obtaining a rubbery polymer with a small particle diameter (for example, a volume-average particle diameter of 100 nm or less) by emulsion polymerization, and then enlarging this small-particle-diameter rubbery polymer. Methods for enlarging in this case include, for example, applying shear force to the small-particle-diameter rubbery polymer using a Manton-Gorin homogenizer to cause aggregation and enlargement, or chemically enlarging the rubbery polymer by adding an acidic substance such as an inorganic acid, organic acid, or an acid group-containing copolymer to latex. A characteristic of rubbery polymers produced by such methods is their broad particle size distribution.

[0024] Furthermore, rubbery polymers can be produced, for example, by using a method that involves emulsion polymerization and enlargement under conditions that reduce the number of particles by using a small amount of emulsifier. Rubbery polymers produced by this method are characterized by a narrow particle size distribution. The particle size of rubbery polymers can be measured by diluting the latex of the rubbery polymer with pure water and using a laser diffraction scattering particle size analyzer (Coulter LS230). In addition, the particle size distribution of graft copolymer (A) can be measured by stirring 1 g of graft copolymer (A) in 100 g of dimethylformamide (DMF) for 24 hours, then adding more DMF to dilute it to an appropriate concentration (the concentration with the best sensitivity when measured by the analyzer), and then using a laser diffraction scattering particle size analyzer.

[0025] Examples of aromatic vinyl monomers used in the graft copolymer (A) include styrene, α-methylstyrene, chlorostyrene, butylstyrene, vinyltoluene, and divinylstyrene. On the other hand, examples of vinyl cyanide monomers used in the graft copolymer (A) include acrylonitrile, methacrylonitrile, and ethacrylonitrile. Furthermore, vinyl monomers copolymerizable with these and used as needed in the graft copolymer (A) include (meth)acrylic acid ester monomers such as methyl (meth)acrylate and butyl (meth)acrylate, and maleimide monomers such as n-methylmaleimide and n-phenylmaleimide. In one embodiment, the graft copolymer (A) is preferably an acrylonitrile-butadiene-styrene copolymer (ABS resin).

[0026] Graft copolymer (A) is preferably obtained by emulsion graft polymerization of 30 to 90 parts by mass of a monomer mixture in the presence of 10 to 70 parts by mass of the above-mentioned rubbery polymer. By setting the amount of rubbery polymer within the above range, the appearance of the molded product can be improved, as well as the impact resistance and productivity of the resin composition. The monomer mixture preferably contains 10% to 40% by mass of vinyl cyanide monomers, 60% to 90% by mass of aromatic vinyl monomers, and 0% to 30% by mass of monomers copolymerizable with these. During emulsion graft polymerization, it is preferable to add, in addition to the monomer mixture, a polymerization initiator, an emulsifier, a chain transfer agent, etc., to the latex of the rubbery polymer.

[0027] As polymerization initiators, at least one of the following can be used: organic hydroperoxides such as cumene hydroperoxide and diisopropylbenzene hydroperoxide; organic peroxyesters such as t-butyl peroxyacetate, t-hexyl peroxybenzoate, and t-butyl peroxybenzoate; persulfates such as potassium persulfate and ammonium persulfate; and diazo compounds such as azobisbutyronitrile. In addition to these polymerization initiators, reducing agents such as iron ions, secondary reducing agents such as sodium formaldehyde sulfoxylate, and chelating agents such as tetrasodium ethylenediaminetetraacetate can also be used in combination.

[0028] Various surfactants such as anionic surfactants, nonionic surfactants, and amphoteric surfactants can be used as emulsifiers, but it is preferable to use a first higher fatty acid or its salt, a second higher fatty acid or its salt, or a mixture thereof, as described above. In the latter case, the content of the first higher fatty acid or its salt in the mixture is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less. On the other hand, the content of the second higher fatty acid or its salt in the mixture is preferably 60% by mass or more and 95% by mass or less, more preferably 65% ​​by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less.

[0029] Examples of chain transfer agents that can be used include n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, α-methylstyrene dimer, ethyl thioglycolate, limonene, and terpinolene. In this embodiment, sulfur-containing chain transfer agents such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and ethyl thioglycolate are preferably used as chain transfer agents. By using sulfur-containing chain transfer agents, it is easier to adjust the balance of various physical properties of the resulting resin composition.

[0030] The amount of emulsifier added when performing emulsion graft polymerization is preferably 0.1 parts by mass to 10 parts by mass, more preferably 0.5 parts by mass to 7.5 parts by mass, and even more preferably 1 part by mass to 5 parts by mass, per 100 parts by mass of the rubbery polymer. Furthermore, the precipitating agent used for precipitation (salting out) of the graft copolymer (A) can be at least one selected from the group consisting of sulfuric acid, acetic acid, magnesium sulfate, hydrochloric acid, and calcium chloride. The temperature in emulsion graft polymerization is not particularly limited, but is preferably 30°C to 90°C, more preferably 40°C to 80°C, and even more preferably 50°C to 70°C.

[0031] The graft copolymer (A) can be recovered by, for example, (i) dewatering the slurry (latex after the addition of a precipitating agent) using a centrifugal dewatering machine or press dewatering machine, and then drying it with an air-flow dryer, etc., or (ii) simultaneously dewatering and drying using a compression dewatering machine or extruder, etc. The bulk density of the graft copolymer (A) can be measured by placing the thoroughly dried graft copolymer (A) in a cylindrical container and heating it to 100 cm³. ３ This can be done by filling the container and measuring its mass. In this specification, the measurement of bulk density shall be carried out in accordance with JIS K 6721:1977.

[0032] The content of the rubbery polymer in the graft copolymer (A) is preferably 40% to 70% by mass, and more preferably 45% to 65% by mass. In this case, the impact resistance of the graft copolymer (A) can be improved. The content of the rubbery polymer in the graft copolymer (A) can be adjusted, for example, by the ratio of aromatic vinyl monomers and vinyl cyanide monomers used to the rubbery polymer during emulsion graft polymerization. Furthermore, the constituent units of the graft copolymer (A), excluding the rubbery polymer, preferably consist of aromatic vinyl monomer units at 65% to 85% by mass and vinyl cyanide monomer units at 15% to 35% by mass. With this configuration, the impact resistance and chemical resistance of the graft copolymer (A) can be further improved.

[0033] The graft copolymer (A) is preferably in particulate form. The graft copolymer (A) is a rubbery polymer particle formed by graft copolymerization of aromatic vinyl monomers, vinyl cyanide monomers, etc., and is insoluble in organic solvents such as methyl ethyl ketone (MEK) and toluene, and is separated by centrifugation. Such particles are also called gel components. The graft copolymer (A) may also form an occlusion structure in which aromatic vinyl-vinyl cyanide copolymer is encapsulated in particulate form within the rubbery polymer particles. In a resin composition obtained by melt-blending graft copolymer (A) and copolymer (B), the gel components exist as a dispersed particulate phase within the continuous phase of copolymer (B).

[0034] The volume-average particle diameter of the graft copolymer (A), i.e., the volume-average particle diameter of the gel portion, is preferably about 0.1 μm to 1 μm, and more preferably about 0.15 μm to 0.5 μm. In this case, the impact resistance of the graft copolymer (A) is increased, and the appearance of the molded product tends to be good. In this specification, the volume-average particle diameter is a value calculated from image analysis of particles dispersed in a continuous phase by cutting an ultrathin section from a pellet of a resin composition obtained by melt-blending graft copolymer (A) and copolymer (B), and observing it with a transmission electron microscope (TEM). The volume-average particle diameter can be adjusted, for example, by the particle diameter of the rubbery polymer used during emulsion graft polymerization. The particle diameter of the rubbery polymer can be adjusted by the method of adding the emulsifier and the amount of water used during emulsion polymerization.

[0035] The grafting rate of the graft copolymer (A) is preferably 10% by mass or more and 100% by mass or less, and more preferably 20% by mass or more and 70% by mass or less. In this case, the impact resistance of the graft copolymer (A) can be further improved. In this specification, the grafting rate is a value calculated based on the gel content (G) and rubbery polymer content (RC) of the graft copolymer (A) using the formula: grafting rate (mass%) = [(G - RC) / RC] × 100. The grafting rate represents the amount of aromatic vinyl-vinyl cyanide copolymer and aromatic vinyl-vinyl cyanide copolymer encapsulated in the particles of the rubbery polymer, to which the rubbery polymer particles are bonded by grafts contained per unit mass of the rubbery polymer. The grafting rate can be adjusted, for example, by setting the ratio of monomers to rubbery polymers, the type and amount of polymerization initiator, the amount of chain transfer agent, the amount of emulsifier, the polymerization temperature, the charging method (all at once / multi-stage / continuous), the monomer addition rate, etc., when performing emulsion graft polymerization.

[0036] The toluene swelling degree of the graft copolymer (A) is preferably between 5 and 20 times. This further enhances the impact resistance of the graft copolymer (A) and makes it easier to obtain a good appearance for the molded product. In this specification, the toluene swelling degree represents the degree of crosslinking of the rubbery polymer particles and is a value calculated from the ratio of the mass of the swollen state with toluene to the mass of the dry state after removing toluene by vacuum drying, after dissolving the graft copolymer (A) in toluene and separating the insoluble matter by centrifugation or filtration. The toluene swelling degree is influenced, for example, by the degree of crosslinking of the rubbery polymer used in emulsion graft polymerization, and this can be adjusted by selecting the polymerization initiator and / or emulsifier during emulsion polymerization of the rubbery polymer, setting the polymerization temperature, adding a polyfunctional monomer such as divinylbenzene, etc.

[0037] <<Copolymer (B)>> Copolymer (B) is a copolymer comprising an aromatic vinyl monomer, a vinyl cyanide monomer, and a vinyl monomer copolymerizable with these as needed. Examples of aromatic vinyl monomers used in copolymer (B) include styrene, α-methylstyrene, and vinyltoluene. Examples of vinyl cyanide monomers used in copolymer (B) include acrylonitrile, methacrylonitrile, and ethacrylonitrile. Examples of vinyl monomers copolymerizable with these and used as needed in copolymer (B) include (meth)acrylic acid ester monomers such as methyl (meth)acrylate and butyl (meth)acrylate, and maleimide monomers such as n-methylmaleimide and n-phenylmaleimide. In one embodiment, copolymer (B) is preferably an acrylonitrile-styrene copolymer (AS resin or SAN resin).

[0038] The copolymer (B) preferably contains 10% by mass or more and 40% by mass or less of a vinyl cyanide-based monomer, 60% by mass or more and 90% by mass or less of an aromatic vinyl-based monomer, and 0% by mass or more and 30% by mass or less of a vinyl-based monomer copolymerizable therewith. By setting the content of the vinyl cyanide-based monomer within the above range, the molding processability of the resin composition is improved, and chemical resistance, impact resistance and heat resistance can be enhanced. Furthermore, by setting the content of the aromatic vinyl-based monomer within the above range, the molding processability of the resin composition is improved, and impact resistance and chemical resistance can be enhanced. Furthermore, by setting the content of the copolymerizable vinyl-based monomer within the above range, the balance of molding processability, impact resistance, heat resistance and the like of the resin composition can be improved.

[0039] The resin composition is preferably composed of 10 parts by mass or more and 50 parts by mass or less of the graft copolymer (A) and 50 parts by mass or more and 90 parts by mass or less of the copolymer (B), and the content of the rubbery polymer in the resin composition is 3% by mass or more and 35% by mass or less. More preferably, the resin composition is composed of 15 parts by mass or more and 45 parts by mass or less of the graft copolymer (A) and 55 parts by mass or more and 85 parts by mass or less of the copolymer (B), and the content of the rubbery polymer in the resin composition is 5% by mass or more and 30% by mass or less. By setting the content of the graft copolymer (A) and the content of the rubbery polymer in the resin composition within the above respective ranges, the impact strength of the resin composition can be improved, the molding processability and rigidity can be enhanced, and the appearance of a molded article can be improved.

[0040] The resin composition is preferably used in pellet form by melt-kneading a graft copolymer (A) and copolymer (B) in an extruder or the like. Suitable extruders include, for example, twin-screw extruders, single-screw extruders, multi-screw extruders, and continuous kneaders with twin rotors. Multiple such extruders can also be used in combination. The extruder has, for example, a kneading section for melt-kneading the graft copolymer (A) and copolymer (B), and at least one defoliation section. The graft copolymer (A) and copolymer (B) supplied to the extruder are first melted in the kneading section and kneaded to a uniform composition. The kneading section is composed of a combination of mixing elements such as a kneading disc. Downstream of the kneading section, it is preferable to use an element that pushes the molten resin back to the upstream side, filling the kneading section, from the viewpoint of kneadability. Examples of such elements include reverse lead full flight, reverse offset kneading, and seal rings.

[0041] The resin composition, melt-kneaded in the kneading section, is transported in a molten state to the defoliation section, where volatile components are defoliated by vacuum venting. The defoliated molten resin composition is extruded in a strand shape from a porous die and cut using methods such as cold-cut, air-hot-cut, or underwater-hot-cut to obtain a pellet-shaped resin composition. As a method of defoliation extrusion, the water-addition defoliation method, in which water is added before the defoliation section, is preferred because it offers excellent defoliation efficiency. For example, a method can be used in which graft copolymer (A) and copolymer (B) are melt-kneaded in the kneading section, then a further kneading section is provided to uniformly knead and disperse water into the molten resin composition, and the volatile components are defoliated together with the water in the downstream defoliation section. It is also preferable that the kneading section where water is added and kneaded be filled to capacity. The amount of water added is preferably 0.05% by mass or more and 2% by mass or less relative to the resin composition.

[0042] The cylinder temperature of the kneading section and devolatilization section of the extruder is not particularly limited, but is preferably about 150°C or higher and 280°C or lower, more preferably about 170°C or higher and 260°C or lower, and further preferably about 190°C or higher and 240°C or lower. Setting a higher cylinder temperature tends to increase the devolatilization efficiency of volatile components from the resin composition. In addition, the pressure in the devolatilization section is preferably set to about 10 mmHg or less when water is not added, and about 40 mmHg or less when water is added. Here, the volatile components include monomers derived from the graft copolymer (A) and the copolymer (B), substances derived from solvent components, substances derived from monomer components generated by thermal decomposition, surfactants added as emulsifiers, substances derived from fatty acids (higher fatty acids) or salts thereof, and impurities mixed in emulsifiers (e.g., glycerin), etc.

[0043] During kneading, additives such as lubricants, pigments, dyes, antioxidants, ultraviolet absorbers, and reinforcing agents such as glass fiber and talc may be added to the resin composition as needed. In the present embodiment, silicone oil is suitably used as the lubricant. By using silicone oil, it is easy to adjust the balance of various physical properties of the obtained resin composition. In the method for producing a resin composition as described above, the content of glycerin in the resin composition can be adjusted, for example, by changing at least one of conditions in the precipitation step of the graft copolymer (A), conditions in the extrusion step of the resin composition, and separate addition of glycerin. In particular, when the graft copolymer (A) is produced by emulsion polymerization, if a fatty acid or a salt thereof is used as an emulsifier, glycerin generated when the fatty acid or a salt thereof is prepared from fats and oils can be utilized as glycerin contained in the resin composition without highly removing the glycerin.

[0044] <Characteristics of the Resin Composition> The resin composition preferably has a melt mass flow rate (MFR) of approximately 5 g / 10 min or more, more preferably 10 g / 10 min or more, and even more preferably 15 g / 10 min or more, measured under conditions of 220°C and 10 kg load in accordance with JIS K 7210:1999 (ISO 1133:1997). The upper limit of the MFR of the resin composition is usually 30 g / 10 min. The MFR of the resin composition can be, for example, between 5 g / 10 min and 30 g / 10 min or less. A resin composition having such a melt mass flow rate can be evaluated as having excellent fluidity and good moldability.

[0045] The resin composition preferably has a bending strength of approximately 62 MPa or more, more preferably 72 MPa or more, and even more preferably 82 MPa or more, measured at a density of 2 mm / min in accordance with JIS K 7171:2016 (ISO 178:2010). The upper limit of the bending strength of the resin composition is usually around 100 MPa. The bending strength of the resin composition can be, for example, between 62 MPa and 100 MPa. Molded articles obtained from a resin composition having such bending strength can be judged to have excellent mechanical strength.

[0046] The resin composition has a Charpy impact strength of 8 kJ / m², measured at 23°C using a notched test specimen in accordance with JIS K 7111-1:2012. ２ It is preferable that it be around 13 kJ / m ２ 35kJ / m or more ２ It is more preferable that it be approximately 18 kJ / m ２ 30kJ / m or more ２ It is even more preferable that the Charpy impact strength is within the following range. Molded articles obtained from such resin compositions can be evaluated as having high toughness.

[0047] Furthermore, the resin composition preferably has a glossiness of 92% or higher, more preferably 94% or higher, even more preferably 96% or higher, and may be 100%, as measured at a 60° measuring angle in accordance with JIS Z 8741:1997. Molded articles obtained from such a resin composition can be evaluated as having extremely high glossiness. The resin composition preferably has a load deflection temperature of 75°C or higher, more preferably 77.5°C to 95°C, and even more preferably 80°C to 90°C, as measured under flatwidth and 1.8 MPa conditions in accordance with JIS K 7191-1, -2:2015. Molded articles obtained from such a resin composition can be evaluated as having extremely high mechanical strength.

[0048] Furthermore, for a 2 mm thick sample prepared using the resin composition, the yellowness (YI) measured in accordance with JIS K 7373:2006 is preferably about 50 or less, more preferably about 35 to 47.5, even more preferably about 36 to 45, and particularly preferably about 37 to 42.5. Molded articles obtained from such resin compositions can be evaluated as having good hue. Furthermore, they may be provided in the embodiments described below.

[0049] (1) A resin composition comprising an acrylonitrile-butadiene-styrene copolymer (ABS resin) and glycerin, wherein the glycerin content in the resin composition is less than 100 ppm.

[0050] (2) The resin composition described in (1) above, wherein the content of glycerin in the resin composition is 0.1 ppm or more and less than 100 ppm.

[0051] (3) A resin composition according to (1) or (2) above, further comprising a fatty acid or a salt thereof.

[0052] (4) The resin composition described in (3) above, wherein the fatty acid or salt thereof comprises at least one of a first higher fatty acid having 12 or more carbon atoms and 14 or less carbon atoms, and a second higher fatty acid having 16 or more carbon atoms and 18 or less carbon atoms, or a salt thereof.

[0053] (5) The resin composition described in (4) above, wherein the first higher fatty acid or a salt thereof comprises myristic acid or a salt thereof, and the second higher fatty acid or a salt thereof comprises linoleic acid or a salt thereof.

[0054] (6) A resin composition according to any one of (1) to (5) above, wherein the melt mass flow rate (MFR) measured in accordance with JIS K 7210:1999 at a temperature of 220°C and a load of 10 kg is 5 g / 10 min or more.

[0055] (7) In the resin composition described in any one of (1) to (6) above, the Charpy impact strength measured at 23°C using a notched test piece in accordance with JIS K 7111-1:2012 is 8 kJ / m ２ The above is the resin composition.

[0056] (8) A resin composition according to any one of (1) to (7) above, wherein the temperature of deflection under load measured flatwise at 1.8 MPa in accordance with JIS K 7191-1, -2:2015 is 75°C or higher. Of course, this is not limited to this.

[0057] Finally, while various embodiments relating to this disclosure have been described, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0058] The resin composition will be described in more detail below based on the examples, but is not limited to these examples. 1. Production of polybutadiene (rubber-like polymer) First, 153 parts by mass of ion-exchanged water was added to an autoclave, and while stirring, 15 parts by mass of an 18% by mass aqueous solution of plant-derived higher fatty acid potassium (emulsifier), 0.08 parts by mass of divinylbenzene (crosslinking agent), 0.2 parts by mass of t-dodecyl mercaptan (chain transfer agent), 0.1 parts by mass of potassium persulfate (polymerization initiator), 0.3 parts by mass of potassium chloride, and 0.001 parts by mass of ethylenediaminetetraacetate tetrahydrate (chelating agent) were added and dissolved.

[0059] Subsequently, 100 parts by mass of butadiene were added, and the temperature was raised to 62°C for 8 hours of polymerization. Then, the temperature was raised to 70°C for a further 7 hours of polymerization. After polymerization was complete, the pressure was removed to remove the remaining butadiene and obtain polybutadiene latex with small particle size. This polybutadiene latex was then enlarged using a Manton-Gorin homogenizer (pressure-assisted flocculant) to obtain polybutadiene latex. The obtained polybutadiene latex had a solid content of 38% by mass and a volume-average particle size of polybutadiene of 320 nm.

[0060] 2. Production of grafted ABS resin (grafted copolymer (A)) First, 100 parts by mass of polybutadiene latex was added to an autoclave, and while stirring, 5 parts by mass of acrylonitrile, 12 parts by mass of styrene, 0.1 parts by mass of t-dodecyl mercaptan (chain transfer agent), and 48 parts by mass of deionized water were added and the temperature was raised. After reaching 50°C, 0.06 parts by mass of ferrous sulfate (reducing agent), 0.2 parts by mass of tetrasodium ethylenediaminetetraacetate tetrahydrate (chelating agent), and 4 parts by mass of sodium formaldehyde sulfoxylate dihydrate (secondary reducing agent: rongalit dihydrate) were added and polymerization was started. Forty minutes after reaching 50°C, an additional 0.06 parts by mass of ferrous sulfate (reducing agent), 0.2 parts by mass of tetrasodium ethylenediaminetetraacetate tetrahydrate (chelating agent), and 4 parts by mass of sodium formaldehyde sulfoxylate dihydrate (secondary reducing agent: Longalit dihydrate) were added.

[0061] Furthermore, a mixture of 0.1 parts by mass of diisopropylbenzene hydroperoxide (polymerization initiator: manufactured by Nippon Oil & Fats Co., Ltd., "Parkmil P"), 0.2 parts by mass of t-butyl peroxyacetate (polymerization initiator: manufactured by Arkema Yoshitomi Co., Ltd., "Lupazol-70"), 3 parts by mass of an 18% aqueous solution of plant-derived higher fatty acid potassium (emulsifier), 9 parts by mass of acrylonitrile, 21 parts by mass of styrene, 0.4 parts by mass of t-dodecyl mercaptan (chain transfer agent), and 13 parts by mass of ion-exchanged water was continuously added over 4 hours from the start of polymerization. After the addition was completed, the mixture was stirred at 70°C for 2 hours to complete the polymerization. This latex was added to saline solution prepared with 203 parts by mass of ion-exchanged water, 2.2 parts by mass of magnesium sulfate heptahydrate (precipitating agent), and 0.9 parts by mass of 20% sulfuric acid (precipitating agent) to precipitate (salt out) and obtain grafted ABS resin.

[0062] 3. Production of AS resin (polymer (B)) The feed solution to be supplied to a 50 L reaction vessel was prepared with 54 parts by mass of styrene, 20 parts by mass of acrylonitrile, 26 parts by mass of ethylbenzene, 0.02 parts by mass of t-butyl peroxyisopropyl carbonate (polymerization initiator) as a polymerization initiator, and 0.06 parts by mass of n-dodecyl mercaptan (chain transfer agent) as a chain transfer agent. After bubbling this feed solution with nitrogen gas and passing through a mixer, it was continuously supplied to the reaction vessel at a rate of 10 L / hour into the liquid phase of the polymerization solution. The polymerization temperature was maintained at 144°C, and the filling rate of the reaction solution in the reaction vessel was maintained at 60 vol%, and the same amount of reaction solution as the feed solution was continuously withdrawn. The evaporated gas generated in the reaction vessel was condensed in a heat exchanger outside the reaction vessel, and the condensed liquid was returned to the liquid phase of the reaction vessel. The extracted reaction solution was introduced into a volatile matter removal device maintained at 250°C and a high vacuum of 11 mmHg, where unreacted monomers and organic solvents were devolved and recovered to obtain pelletized AS resin.

[0063] 4. Production of Resin Composition (Example 1) A pelletized resin composition was produced by blending 22 parts by mass of grafted ABS resin and 78 parts by mass of AS resin and melt-kneading them at a temperature of 225°C using a twin-screw extruder. In order to remove residual volatile matter, defloration was performed by vacuum venting and water injection defloration.

[0064] (Example 2) A pellet-shaped resin composition was produced in the same manner as in Example 1, except that 250 ppm of glycerin was added based on 100 parts by mass in total of the graft ABS resin and the AS resin. (Example 3) A pellet-shaped resin composition was produced in the same manner as in Example 1, except that the brine used for precipitation (salting out) of the graft ABS resin was changed to brine prepared with 406 parts by mass of ion-exchanged water, 4.4 parts by mass of magnesium sulfate heptahydrate (precipitating agent) and 1.8 parts by mass of 20 mass% sulfuric acid (precipitating agent), and the temperature at the time of melt-kneading the graft ABS resin and the AS resin was changed to 260°C.

[0065] (Example 4) A pellet-shaped resin composition was produced in the same manner as in Example 1, except that 42 parts by mass of the graft ABS resin and 58 parts by mass of the AS resin were blended. (Comparative Example) A pellet-shaped resin composition was produced in the same manner as in Example 1, except that 500 ppm of glycerin was added based on 100 parts by mass in total of the graft ABS resin and the AS resin.

[0066] 5. Measurement and Evaluation 5-1. Measurement of Higher Fatty Acid Content The higher fatty acid content in each resin composition was measured by the following procedure. The freeze-pulverized resin composition was extracted with ethanol for 1.5 hours using an Exfat extractor. Thereafter, the extract was concentrated and filtered through a membrane filter to obtain a measurement sample. This was measured using LC-10 CLASS-VP manufactured by Shimadzu Corporation (detector: RID-10A, column: YMC ODS-A, mobile phase: MeOH: 1000 mL / H ２ O (0.5% H ３ PO ４ / H ２ O): 80 mL).

[0067] 5-2. Measurement of Glycerin Content The glycerin content in each resin composition was measured by the following procedure. First, 5 mL of acetone was added to 0.5 g of the resin composition and allowed to stand for 12 hours, then shaken in a shaker for 12 hours to dissolve. Next, 5 mL of methanol was added to reprecipitation, and the supernatant was filtered through a 0.45 μm membrane filter to obtain the measurement sample. Then, 1.0 μL of the sample to be measured and 0.2 μL of a 10% by mass tetramethylammonium hydroxide / methanol solution were simultaneously injected into a JEOL Ltd. JMS-Q1500GC (column: DB-WAX 0.25 mm 0.50 μm 30 m, column temperature: 70°C HOLD 5 min, heating rate 10°C / min, 200°C HOLD 12 min, split ratio 30:1, column flow rate 1 mL / min, measurement range: m / z = 29 to 550, quantitative ion: m / z = 59 (reference ions m / z = 45, 89)) and measured.

[0068] 5-3. Measurement of Melt Mass Flow Rate (MFR) The melt mass flow rate (MFR) of the resin compositions of each example and comparative example was measured in accordance with JIS K 7210:1999, under conditions of a temperature of 220°C and a load of 10 kg. 5-4. Measurement of Charpy Impact Strength The Charpy impact strength of the resin compositions of each example and comparative example was measured in accordance with JIS K 7111-1:2012, using notched test specimens at 23°C.

[0069] 5-5. Measurement of Load Deflection Temperature The load deflection temperature of the resin compositions of each example and comparative example was measured flatwise at 1.8 MPa in accordance with JIS K 7191-1, -2:2015. 5-6. Evaluation of Mold Fouling The degree of mold fouling due to the adhesion of low molecular weight components from the resin was visually evaluated during injection molding of the resin compositions of each example and comparative example according to the following criteria: A: No fouling occurred even after 1500 shots. B: Fouling occurred between 1000 and 1500 shots. C: Fouling occurred in less than 1000 shots.

[0070] 5-7. Measurement of Yellowness (YI) The yellowness (YI) of 2 mm thick samples prepared using the resin compositions of each example and comparative example was measured in accordance with JIS K 7373:2006. These results are shown in Table 1 below.

[0071] As shown in Table 1, the resin compositions of each example exhibited superior mold fouling properties compared to the comparative example's resin composition, due to the appropriate adjustment of the glycerin content. Furthermore, it was confirmed that various physical properties of the resin compositions could be controlled by adjusting the glycerin content in each example's resin composition.

Claims

1. A resin composition comprising an acrylonitrile-butadiene-styrene copolymer (ABS resin) and glycerin, wherein the glycerin content in the resin composition is less than 100 ppm.

2. The resin composition according to claim 1, wherein the content of glycerin in the resin composition is 0.1 ppm or more and less than 100 ppm.

3. A resin composition according to claim 1 or claim 2, further comprising a fatty acid or a salt thereof.

4. The resin composition according to claim 3, wherein the fatty acid or salt thereof comprises at least one of a first higher fatty acid or salt thereof having 12 to 14 carbon atoms, and a second higher fatty acid or salt thereof having 16 to 18 carbon atoms.

5. The resin composition according to claim 4, wherein the first higher fatty acid or a salt thereof comprises myristic acid or a salt thereof, and the second higher fatty acid or a salt thereof comprises linoleic acid or a salt thereof.

6. A resin composition according to claim 1 or claim 2, wherein the melt mass flow rate (MFR), measured in accordance with JIS K 7210:1999 at a temperature of 220°C and a load of 10 kg, is 5 g / 10 min or more.

7. In the resin composition according to claim 1 or claim 2, the Charpy impact strength measured at 23°C using a notched test piece in accordance with JIS K 7111-1:2012 is 8 kJ / m ２ The above is the resin composition.

8. A resin composition according to claim 1 or claim 2, wherein the temperature of deflection under load measured flatwise at 1.8 MPa in accordance with JIS K 7191-1, -2:2015 is 75°C or higher.

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