Thermoplastic resin composition for foam molding and foam molded product thereof

Abstract

The present invention provides a thermoplastic resin composition for foam molding, wherein the composition contains 0.1 to 10 parts by mass of a high molecular weight resin (D) having a weight average molecular weight of 2 million or more, relative to 100 parts by mass of a total of 1 to 20 parts by mass of the following component (A), 0 to 50 parts by mass of the following component (B), and 40 to 90 parts by mass of the following component (C). Component (A): a rubber-reinforced styrene resin (A) obtained by polymerizing a vinyl monomer (b1) containing an aromatic vinyl compound in the presence of a rubber polymer (a); component (B): a styrene resin (B) obtained by polymerizing a vinyl monomer (b2) containing an aromatic vinyl compound; component (C): an aromatic polycarbonate resin (C).

Description

Technical Field

[0001] The present invention relates to a thermoplastic resin composition for foam molding, which exhibits a fine foaming cell structure in injection foam molding, and the size of the foaming cells is uniform regardless of the location of the foamed molded product, and can mold a foamed molded product with excellent mechanical properties and excellent surface appearance. The present invention also relates to a foamed molded product using the thermoplastic resin composition for foam molding. Background Art

[0002] In the injection molding method using thermoplastic resin, injection foaming is well known, in which a foaming agent is added to a resin material to perform injection molding in order to reduce the amount of resin components used, reduce weight, etc. As the foaming agent used in injection foaming, thermal decomposition type chemical foaming agents such as azodicarboxamide are known (Patent Document 1). In addition, physical foaming agents that use nitrogen, carbon dioxide, etc. as foaming agents instead of chemical foaming are also known. In addition, a method using a physical foaming agent in a supercritical state has also been proposed.

[0003] As thermoplastic resin compositions for foam molding, the following compositions have been proposed.

[0004] (1) A thermoplastic resin composition for foam molding, characterized in that it contains:

[0005] 5 to 90% by weight of a rubber-reinforced styrene resin (A), which is obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a), and the amount of the hot cyclohexane solubility is 1 to 99% by weight based on the rubber polymer (a);

[0006] 0 to 85% by mass of a styrene-based resin (B), which is obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b2) copolymerizable with the aromatic vinyl compound;

[0007] 10 to 90% by mass of an aromatic polycarbonate resin (C); and

[0008] 0.1 to 5 parts by mass of a chemical foaming agent (D) based on 100 parts by mass of the total of the above components (A) to (C),

[0009] The ratio of the rubber polymer (a) is 3 to 50% by mass relative to 100% by mass of the total of the above components (A) to (C) (Patent Document 2).

[0010] (2) A thermoplastic resin composition for foam molding, characterized in that it contains:

[0011] 5 to 90% by weight of a rubber-reinforced styrene resin (A), which is obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a), and the amount of the hot cyclohexane solubility is 1 to 99% by weight based on the rubber polymer (a);

[0012] 0 to 85% by mass of a styrene-based resin (B), which is obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b2) copolymerizable with the aromatic vinyl compound;

[0013] 10 to 90% by mass of an aromatic polycarbonate resin (C); and

[0014] 0.1 to 5 parts by mass of a chemical foaming agent (D), 0.5 to 18 parts by mass of talc (E), and 0.5 to 25 parts by mass of a fibrous filler (F) are added to 100 parts by mass of the total of the above components (A) to (C).

[0015] The ratio of the rubber polymer (a) is 3 to 50% by mass in 100% by mass of the total of the above components (A) to (C) (Patent Document 3).

[0016] Patent Document 1: Japanese Patent Application Publication No. 2008-133485

[0017] Patent Document 2: Japanese Patent Application Publication No. 2010-254833

[0018] Patent Document 3: Japanese Patent Application Publication No. 2011-37925

[0019] The foam-molded article obtained by injection foam molding of the thermoplastic resin composition for foam molding requires the following (i) and (ii).

[0020] (i) It exhibits a fine foaming cell structure at a high foaming ratio. The size of the foaming cells is uniform regardless of the location of the foamed product, and the mechanical properties (especially rigidity) are excellent.

[0021] (ii) There are no surface defects such as unevenness due to swirls or uneven foaming (the swirls or uneven foaming are caused by the transfer of gas released during foaming to the unfoamed outer skin layer formed on the surface of the molded product, which deteriorates the surface properties), and the surface appearance is good

[0022] Based on such viewpoints, further improvement is desired in the thermoplastic resin compositions for foam molding of Patent Documents 2 and 3. Summary of the invention

[0023] The present invention aims to provide a thermoplastic resin composition for foam molding and a foam molded product using the same, wherein the composition exhibits a fine foam cell structure in injection foam molding, the size of the foam cells is uniform regardless of the location of the foam molded product, and a foam molded product having excellent mechanical properties and excellent surface appearance can be molded.

[0024] The present inventors have discovered that by blending a high molecular weight resin (D) into a resin component consisting of a rubber-reinforced styrene resin (A) and an aromatic polycarbonate resin (C), or a rubber-reinforced styrene resin (A), a styrene resin (B) and an aromatic polycarbonate resin (C), leakage of foaming gas during injection foam molding can be suppressed, stable foaming moldability can be exhibited, and the above-mentioned problems can be solved.

[0025] That is, the gist of the present invention is as follows.

[0026] [1] A thermoplastic resin composition for foam molding, comprising 1 to 20 parts by mass of the following component (A), 0 to 50 parts by mass of the following component (B), and 40 to 90 parts by mass of the following component (C), per 100 parts by mass in total, and further comprising 0.1 to 10 parts by mass of a high molecular weight resin (D) different from the components (A) to (C) and having a weight average molecular weight of 2,000,000 or more, relative to 100 parts by mass of the total of the components (A) to (C).

[0027] Component (A): a rubber-reinforced styrene resin (A) prepared by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a).

[0028] Component (B): a styrene resin (B) obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b2) copolymerizable with the aromatic vinyl compound.

[0029] Component (C): Aromatic polycarbonate resin (C)

[0030] [2] The thermoplastic resin composition for foam molding as described in [1], wherein the weight average molecular weight of the high molecular weight resin (D) is 2.5 million to 7 million.

[0031] [3] The thermoplastic resin composition for foam molding according to [1] or [2], further comprising 0.1 to 5 parts by mass of a chemical foaming agent (E) based on 100 parts by mass of the total of the components (A) to (C).

[0032] [4] The thermoplastic resin composition for foam molding according to any one of [1] to [3], further comprising 0.1 to 20 parts by mass of an inorganic filler (F) based on 100 parts by mass of the total amount of the components (A) to (C).

[0033] [5] The thermoplastic resin composition for foam molding according to any one of [1] to [4], which is used for core-return type injection foam molding.

[0034] [6] A foam-molded article obtained by molding the thermoplastic resin composition for foam molding according to any one of [1] to [5].

[0035] [7] A foam-molded article obtained by subjecting the thermoplastic resin composition for foam molding according to any one of [1] to [5] to core-return type injection foam molding.

[0036] Effects of the Invention

[0037] The thermoplastic resin composition for foam molding according to the present invention exhibits a fine foam cell structure in injection foam molding, and the size of the foam cells is uniform regardless of the location of the foam molded product, thereby providing a foam molded product having excellent mechanical properties and excellent surface appearance. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below.

[0039] [Thermoplastic resin composition for foam molding]

[0040] The thermoplastic resin composition for foam molding of the present invention contains 1 to 20 parts by mass of the following component (A), 0 to 50 parts by mass of the following component (B), and 40 to 90 parts by mass of the following component (C) per 100 parts by mass in total, and contains 0.1 to 10 parts by mass of a high molecular weight resin (D) (hereinafter sometimes referred to as "component (D)") different from the components (A) to (C) and having a weight average molecular weight of 2,000,000 or more, relative to 100 parts by mass of the total of the components (A) to (C).

[0041] Component (A): a rubber-reinforced styrene resin (A) prepared by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a).

[0042] Component (B): a styrene resin (B) obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b2) copolymerizable with the aromatic vinyl compound.

[0043] Component (C): Aromatic polycarbonate resin (C)

[0044] In the present invention, "(co)polymerization" means homopolymerization and copolymerization. "(Meth)acrylate" means at least one of acrylate and methacrylate. The same applies to "(meth)acrylic acid".

[0045] The thermoplastic resin composition for foam molding of the present invention may be simply referred to as “thermoplastic resin composition”.

[0046] [Component (A): rubber-reinforced styrene resin (A)]

[0047] Component (A) is a rubber-reinforced styrene resin (A) obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a).

[0048] Examples of the rubber polymer (a) include conjugated diene rubbers such as polybutadiene, polyisoprene, butadiene·styrene copolymer, butadiene·acrylonitrile copolymer, olefin rubbers such as ethylene·propylene copolymer, ethylene·propylene·non-conjugated diene copolymer, ethylene·butene-1 copolymer, ethylene·butene-1·non-conjugated diene copolymer, acrylic rubber, silicone rubber, polyurethane rubber, silicone·acrylic IPN rubber, natural rubber, conjugated diene block copolymer, hydrogenated conjugated diene block copolymer, and the like.

[0049] The olefin rubber is not particularly limited, and examples thereof include ethylene·α-olefin rubbers containing ethylene and α-olefins having a carbon number of 3 or more. When the total amount of monomers constituting the ethylene·α-olefin rubber is 100% by mass, the ethylene content is preferably 5 to 95% by mass, more preferably 50 to 90% by mass, and further preferably 60 to 88% by mass.

[0050] As α-olefins having 3 or more carbon atoms, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methylbutene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-undecene, etc. can be mentioned. These α-olefins may be included alone or in combination of two or more. Among the above-mentioned α-olefins, propylene and 1-butene are preferred.

[0051] When the total amount of monomers constituting the ethylene / α-olefin rubber is 100 mass%, the content of the α-olefin is preferably 95 to 5 mass%, more preferably 50 to 10 mass%, particularly preferably 40 to 12 mass%.

[0052] The ethylene-α-olefin rubber may be a binary copolymer composed of ethylene and α-olefin, or a polymer composed of these and other compounds (a ternary copolymer, a tetraary copolymer, etc.). Examples of other compounds include non-conjugated diene compounds.

[0053] As the non-conjugated diene compound used in the olefin rubber, alkenyl norbornene, cyclic dienes, aliphatic dienes, etc. can be cited, preferably dicyclopentadiene and 5-ethylidene-2-norbornene. These non-conjugated diene compounds can be used alone or in combination of two or more. The content of the non-conjugated diene compound unit in the ethylene α-olefin rubber is usually less than 30% by mass, preferably less than 15% by mass.

[0054] The acrylic rubber is not particularly limited, but is preferably a (co)polymer of an alkyl (meth)acrylate compound having an alkyl group with 1 to 8 carbon atoms, or a copolymer of the alkyl (meth)acrylate compound and a vinyl monomer copolymerizable therewith.

[0055] Specific examples of alkyl acrylate compounds having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, pentyl acrylate, hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, etc. Specific examples of alkyl methacrylate compounds include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, etc. Among these compounds, n-butyl acrylate and 2-ethylhexyl acrylate are preferred. They can be used alone or in combination of two or more.

[0056] Examples of the vinyl monomer copolymerizable with the alkyl (meth)acrylate compound include polyfunctional vinyl compounds, aromatic vinyl compounds, and vinyl cyanide compounds.

[0057] A multifunctional vinyl compound refers to a monomer having two or more vinyl groups in one molecule of the monomer, which has the function of cross-linking the (meth) acrylic rubber and serves as a reaction starting point during graft polymerization. Specific examples of multifunctional vinyl monomers include multifunctional aromatic vinyl compounds such as divinylbenzene and divinyltoluene; (meth) acrylic acid esters of polyols such as (poly)ethylene glycol dimethacrylate and trimethylolpropane triacrylate; diallyl maleate, diallyl fumarate, triallyl cyanurate, triallyl cyanurate, diallyl phthalate, allyl methacrylate, etc. These multifunctional vinyl compounds can be used alone or in combination of two or more.

[0058] As aromatic vinyl compounds and vinyl cyanide compounds, all of the substances described below can be used. Furthermore, as other copolymerizable monomers, acrylamide, methacrylamide, vinylidene chloride, alkyl vinyl ethers having 1 to 6 carbon atoms in the alkyl group, (meth) alkyl acrylates having 9 or more carbon atoms in the alkyl group, (meth) acrylic acid, etc. can be cited. These can be used alone or in combination of two or more.

[0059] The preferred monomer composition of the acrylic rubber is 80 to 99.99 mass %, more preferably 90 to 99.95 mass % of the (meth)acrylic acid alkyl ester compound unit having 1 to 8 carbon atoms in the alkyl group, 0.01 to 5 mass %, more preferably 0.05 to 2.5 mass % of the multifunctional vinyl compound unit, and 0 to 20 mass %, more preferably 0 to 10 mass % of other vinyl monomer units copolymerizable therewith. The total monomer composition is 100 mass %.

[0060] As described below, the amount of heat cyclohexane dissolved in the rubber-reinforced styrene resin (A) is preferably 1 to 99% by mass based on the rubber polymer (a). In order to make the amount of heat cyclohexane dissolved in the rubber-reinforced styrene resin (A) more than 1% by mass based on the rubber polymer (a), when a multifunctional vinyl compound is used in the manufacture of the acrylic rubber, it is preferably carried out in the later stage of polymerization. That is, the acrylic rubber can be manufactured by the following method: in the initial stage of polymerization, the (meth) acrylate alkyl ester compound and other copolymerizable vinyl monomers (b1) are polymerized, and in the later stage of polymerization, the (meth) acrylate alkyl ester compound and the multifunctional vinyl compound and other copolymerizable vinyl monomers (b1) are polymerized.

[0061] As a method for producing the acrylic rubber of the present invention, there are the following methods (1) to (4) and the like.

[0062] (1) Method for polymerizing by adding various vinyl monomers at one time

[0063] (2) A method of adding a specific vinyl monomer at one time to polymerize, and then adding the remaining vinyl monomer at a later stage of polymerization to polymerize

[0064] (3) A method of adding a portion of various vinyl monomers for polymerization and continuously adding the remaining vinyl monomers for polymerization

[0065] (4) A method of polymerizing various vinyl monomers in two or more stages

[0066] The method (4) is preferred, and a method in which a polyfunctional vinyl compound is used in the later stage after the second stage in the method (4) is more preferred.

[0067] As the polymerization method, emulsion polymerization is particularly preferred.

[0068] The volume average particle size of the acrylic rubber is preferably 50 to 1000 nm, more preferably 40 to 700 nm, and particularly preferably 50 to 500 nm.

[0069] The conjugated diene block copolymers include, specifically, copolymers comprising at least one of the following blocks A or C, and at least one of the following blocks B or A / B, or polymers based on blocks B or A / B. They can be produced by known anionic polymerization methods, such as the methods disclosed in Japanese Patent Publication No. 47-28915, Japanese Patent Publication No. 47-3252, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 48-20038, etc.

[0070] Regarding the specific structure of the conjugated diene block copolymer,

[0071] A is defined as an aromatic vinyl compound polymer block,

[0072] B is defined as a conjugated diene polymer block,

[0073] A / B is defined as a random copolymer block of an aromatic vinyl compound / conjugated diene.

[0074] C is defined as a tapered block consisting of a copolymer of a conjugated diene and an aromatic vinyl compound, with the aromatic vinyl compound increasing gradually.

[0075] When , the following structures can be given.

[0076] AB (1)

[0077] ABA (2)

[0078] ABC (3)

[0079] A-B1-B2 (4)

[0080] (Herein, B1 is a conjugated diene polymer block or a copolymer block of a conjugated diene and an aromatic vinyl compound, and the vinyl bond content of the conjugated diene portion is preferably 20% or more, and B2 is a conjugated diene polymer block or a copolymer block of a conjugated diene and an aromatic vinyl compound, and the vinyl bond content of the conjugated diene portion is preferably less than 20%.)

[0081] AA / B (5)

[0082] AA / BC (6)

[0083] AA / BB (7)

[0084] AA / BA (8)

[0085] B2-B1-B2 (9)

[0086] (Here, B1 and B2 are the same as above.)

[0087] CB (10)

[0088] CBC (11)

[0089] CA / BC (12)

[0090] CAB (13)

[0091] The conjugated diene block copolymer may be a copolymer having these basic skeletons repeatedly, or a conjugated diene block copolymer obtained by further coupling them. The substance having the structure of the above formula (4) is shown in Japanese Patent Publication No. 2-133406, and the substances having the structures of the above formula (5) and the above formula (6) are shown in Japanese Patent Publication No. 2-305814 and Japanese Patent Publication No. 3-72512.

[0092] Examples of the conjugated diene used herein include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene, etc. In order to obtain a conjugated diene block copolymer having excellent physical properties and being industrially applicable, 1,3-butadiene, isoprene, and 1,3-pentadiene are preferred, and 1,3-butadiene is more preferred.

[0093] Examples of the aromatic vinyl compound used herein include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, hydroxystyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene, p-tert-butylstyrene, ethylstyrene, vinylnaphthalene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, etc. Styrene and α-methylstyrene are preferred, and styrene is particularly preferred.

[0094] The ratio of the aromatic vinyl compound to the conjugated diene in the conjugated diene block copolymer is 0 to 70 / 100 to 30, preferably 0 to 60 / 100 to 40, more preferably 0 to 50 / 100 to 50, and when the aromatic vinyl compound is essential, it is preferably 10 to 70 / 90 to 30. If the content of the aromatic vinyl compound exceeds 70% by mass, the copolymer becomes resinous and has a poor effect as a rubber component, which is not preferred.

[0095] The vinyl bond content of the conjugated diene portion in the conjugated diene block is usually in the range of 5 to 80%.

[0096] The number average molecular weight of the conjugated diene block copolymer is usually 10,000 to 1,000,000, preferably 20,000 to 500,000, more preferably 20,000 to 200,000.

[0097] It is preferred that the number average molecular weight of the A portion of the above structural formula is in the range of 3,000 to 150,000, and the number average molecular weight of the B portion is in the range of 5,000 to 200,000.

[0098] The number average molecular weight is a value measured by gel permeation chromatography (GPC).

[0099] The amount of vinyl bonds in the conjugated diene compound can be adjusted using amines such as N,N,N',N'-tetramethylethylenediamine, trimethylamine, triethylamine, and diazocyclo(2,2,2)octaamine, ethers such as tetrahydrofuran, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether, sulfides, phosphines, phosphoramides, alkylbenzene sulfonates, potassium or sodium alkoxides, and the like.

[0100] Examples of the coupling agent used in the present invention include diethyl adipate, divinylbenzene, methyldichlorosilane, silicon tetrachloride, butylsilicon trichloride, tin tetrachloride, butyltin trichloride, dimethylsilicon chloride, germanium tetrachloride, 1,2-dibromoethane, 1,4-chloromethylbenzene, bis(trichlorosilyl)ethane, epoxidized linseed oil, toluene diisocyanate, and 1,2,4-benzene triisocyanate.

[0101] The hydrogenated conjugated diene block copolymer is a partially or completely hydrogenated product in which at least 30% or more, preferably 50% or more, and more preferably 90% or more of the carbon-carbon double bonds of the conjugated diene portion of the conjugated diene block copolymer are hydrogenated.

[0102] The hydrogenation reaction of the conjugated diene block copolymer can be carried out using a known method. By adjusting the hydrogenation rate using a known method, the target hydrogenated conjugated diene block copolymer can be obtained. As a specific method, there are Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 63-5401, Japanese Patent Publication No. 2-133406, Japanese Patent Publication No. 1-297413, etc. disclosed methods.

[0103] The rubber polymer (a) used in the present invention preferably has a gel content of 70% by mass or less, more preferably 50% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of the foamability of the foam-molding thermoplastic resin composition.

[0104] The gel content can be determined by the method shown below.

[0105] 1 g of rubber polymer (a) is placed in 100 ml of toluene and allowed to stand at room temperature for 48 hours. It is then filtered using a 100-mesh wire mesh (mass is set to W1 grams), and the filtered toluene-insoluble component and the wire mesh are vacuum dried at a temperature of 80°C for 6 hours and weighed (mass is set to W2 grams). Substitute W1 and W2 into the following formula (14) to obtain the gel content. There are substances with ethylene crystals in ethylene-propylene rubber polymers. When such a rubber polymer is used, it is dissolved at a temperature of 80°C to obtain the gel content.

[0106] Gel content = [[W2(g)-W1(g)] / 1(g)]×100 (14)

[0107] The gel content can be adjusted by appropriately setting the type and amount of the crosslinking monomer, the type and amount of the molecular weight modifier, the polymerization time, the polymerization temperature, the polymerization conversion rate, etc. during the production of the rubber polymer (a).

[0108] Preferred rubber polymers (a) used in the present invention are polybutadiene, butadiene-styrene copolymers, ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, acrylic rubbers, silicone rubbers, conjugated diene block copolymers, and hydrogenated conjugated diene block copolymers. More preferred are ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, acrylic rubbers, conjugated diene block copolymers, and hydrogenated conjugated diene block copolymers. Particularly preferred are acrylic rubbers, ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, conjugated diene block copolymers, and hydrogenated conjugated diene block copolymers. Most preferred are acrylic rubbers having a gel content of 10% by mass or less and a volume average particle size of 50 to 500 nm, particularly 50 to 300 nm.

[0109] The rubber polymer (a) can be obtained by known methods such as emulsion polymerization, solution polymerization, bulk polymerization, suspension polymerization, etc. Among these, acrylic rubber is preferably produced by emulsion polymerization. Ethylene-propylene copolymer, ethylene-propylene-non-conjugated diene copolymer, conjugated diene block copolymer and hydrogenated conjugated diene block copolymer are preferably produced by solution polymerization, and polybutadiene and butadiene-styrene copolymer are preferably produced by solution polymerization.

[0110] Component (A) is obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and other vinyl monomers (b1) copolymerizable with the aromatic vinyl compound in the presence of the rubber polymer (a). The vinyl monomer (b1) may be a single aromatic vinyl compound or a mixture of an aromatic vinyl compound and other vinyl monomers copolymerizable with the aromatic vinyl compound.

[0111] Component (A) is preferably obtained by polymerizing 80 to 30 parts by mass of an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of 20 to 70 parts by mass of the rubber polymer (a) (wherein the total of the rubber polymer (a) and the vinyl monomer (b1) is 100 parts by mass). With regard to this ratio, it is more preferred that the rubber polymer (a) is 30 to 60 parts by mass and the vinyl monomer (b1) is 70 to 40 parts by mass.

[0112] As the aromatic vinyl compound used herein, all of those described in the rubber polymer (a) can be used. Styrene and α-methylstyrene are particularly preferred. These can be used alone or in combination of two or more.

[0113] As other vinyl monomers copolymerizable with aromatic vinyl compounds, cyanide vinyl compounds, (meth) acrylate compounds, maleimide compounds, unsaturated compounds containing other various functional groups, etc. can be cited. As unsaturated compounds containing other various functional groups, unsaturated acid compounds, unsaturated compounds containing epoxy groups, unsaturated compounds containing hydroxyl groups, unsaturated compounds containing anhydride groups, unsaturated compounds containing oxazoline groups, unsaturated compounds containing substituted or unsubstituted amino groups, etc. can be cited. These other vinyl monomers can be used alone or in combination of two or more.

[0114] Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile. They can be used alone or in combination of two or more. By using the vinyl cyanide compound, chemical resistance can be imparted. The amount of the vinyl cyanide compound is generally 0 to 60% by mass, preferably 5 to 50% by mass, based on the proportion in the total amount of the vinyl monomer (b1).

[0115] As the (meth)acrylate compound, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc. can be mentioned. They can be used alone or in combination of two or more. By using the (meth)acrylate compound, the surface hardness is improved. The amount of the (meth)acrylate compound is usually 0 to 80% by mass in terms of the proportion in the total amount of the vinyl monomer (b1).

[0116] As the maleimide compound, maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, N-cyclohexylmaleimide, etc. can be mentioned. They can be used alone or in combination of two or more. In order to introduce the maleimide unit, imidization can be carried out after copolymerization of maleic anhydride. Heat resistance can be imparted by using maleimide compounds. The amount of maleimide compound used is usually 1 to 60 mass % in terms of the proportion in the total amount of vinyl monomer (b1).

[0117] Examples of the unsaturated acid compound include acrylic acid, methacrylic acid, 2-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and cinnamic acid, etc. These may be used alone or in combination of two or more.

[0118] Examples of the epoxy group-containing unsaturated compound include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc. These may be used alone or in combination of two or more.

[0119] Examples of the unsaturated compound containing a hydroxyl group include 3-hydroxy-1-propylene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, 3-hydroxy-3-methyl-1-propylene, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, N-(4-hydroxyphenyl)maleimide, etc. These may be used alone or in combination of two or more.

[0120] Examples of the unsaturated compound containing an oxazoline group include vinyl oxazoline, etc. These may be used alone or in combination of two or more.

[0121] Examples of the unsaturated compound containing an acid anhydride group include maleic anhydride, itaconic anhydride, citraconic anhydride, etc. These may be used alone or in combination of two or more.

[0122] Examples of the unsaturated compound containing a substituted or unsubstituted amino group include aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, phenylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, acrylic amine, N-methylacrylamide, acrylamide, N-methylacrylamide, p-aminostyrene, etc. These may be used alone or in combination of two or more.

[0123] When using unsaturated compounds containing various other functional groups, the compatibility of the rubber-reinforced styrene resin (A) with the styrene resin (B) and the aromatic polycarbonate resin (C) may be improved. The amount of the unsaturated compound containing various other functional groups is usually 0.1 to 20% by mass, preferably 0.1 to 10% by mass, relative to the total amount of the unsaturated compound containing the functional group, relative to the total amount of the component (A) and the component (B).

[0124] The content of the monomers other than the aromatic vinyl compound in the vinyl monomer (b1) is usually 80% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less, when the total amount of the vinyl monomer (b1) is 100% by mass.

[0125] More preferred combinations of monomers constituting the vinyl monomer (b1) are styrene alone, styrene / acrylonitrile, styrene / methyl methacrylate, styrene / acrylonitrile / methyl methacrylate, styrene / acrylonitrile / glycidyl methacrylate, styrene / acrylonitrile / 2-hydroxyethyl methacrylate, styrene / acrylonitrile / (meth)acrylic acid, styrene / N-phenylmaleimide, styrene / methyl methacrylate / cyclohexylmaleimide, etc. More preferred are styrene alone, styrene / acrylonitrile = 65 / 45 to 90 / 10 (mass ratio), styrene / methyl methacrylate = 80 / 20 to 20 / 80 (mass ratio), and a combination of styrene / acrylonitrile / methyl methacrylate in which the amount of styrene is 20 to 80% by mass and the total amount of acrylonitrile and methyl methacrylate is 20 to 80% by mass.

[0126] The rubber reinforced styrene resin (A) can be manufactured by a known polymerization method, such as emulsion polymerization, bulk polymerization, solution polymerization, suspension polymerization, and a polymerization method formed by combining them. In the above-mentioned polymerization method, when the rubber polymer (a) is a substance obtained by emulsion polymerization, it can also be manufactured by emulsion polymerization in the manufacture of component (A). When the rubber polymer (a) is a substance obtained by solution polymerization, component (A) is usually preferably manufactured by bulk polymerization, solution polymerization, and suspension polymerization. Even if it is a rubber polymer (a) manufactured by solution polymerization, if the rubber polymer (a) is emulsified by a known method, component (A) can be manufactured by emulsion polymerization. Even if it is a rubber polymer (a) manufactured by emulsion polymerization, it can be solidified and separated, and then component (A) can be manufactured by bulk polymerization, solution polymerization, and suspension polymerization.

[0127] When the product is produced by emulsion polymerization, a polymerization initiator, a chain transfer agent, an emulsifier, etc. are used, and all of them can use known substances.

[0128] Examples of polymerization initiators include cumene hydroperoxide, terpene hydroperoxide, diisopropylbenzene hydroperoxide, tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide, potassium persulfate, azobisisobutyronitrile, etc. As polymerization initiator aids, redox agents such as various reducing agents, sugar-containing iron pyrophosphate formulations, and sulfoxylate formulations are preferably used.

[0129] Examples of the chain transfer agent include octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, n-hexyl mercaptan, and terpinolenes.

[0130] As the emulsifier, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, aliphatic sulfonates such as sodium lauryl sulfate, higher fatty acid salts such as potassium laurate, potassium stearate, potassium oleate, and potassium palmitate, and rosin acid salts such as potassium rosinate can be used.

[0131] In the emulsion polymerization, the method of using the rubber polymer (a) and the vinyl monomer (b1) is that the vinyl monomer (b1) may be added all at once in the presence of the total amount of the rubber polymer (a) for polymerization, or may be added in portions or continuously for polymerization. Alternatively, a portion of the rubber polymer (a) may be added during the polymerization.

[0132] After emulsion polymerization, the obtained emulsion is usually solidified by a coagulant. Thereafter, the powder of component (A) is obtained by washing with water and drying. At this time, the emulsions of two or more components (A) obtained by emulsion polymerization can be coagulated after being appropriately blended. It is also possible to coagulate after appropriately blending the emulsion of component (B). As a coagulant, inorganic salts such as calcium chloride, magnesium sulfate, magnesium chloride, and acids such as sulfuric acid, acetic acid, citric acid, and malic acid can be used. The powder of component (A) can also be obtained by spray drying the emulsion.

[0133] When producing component (A) by solution polymerization, the solvent that can be used is an inert polymerization solvent generally used in free radical polymerization, for example, aromatic hydrocarbons such as ethylbenzene and toluene, ketones such as methyl ethyl ketone and acetone, acetonitrile, dimethylformamide, N-methylpyrrolidone, etc.

[0134] The polymerization temperature is usually in the range of 80 to 140° C., preferably 85 to 120° C. During the polymerization, a polymerization initiator may be used, or the polymerization may be performed by thermal polymerization without using a polymerization initiator.

[0135] As the polymerization initiator, ketone peroxide, dialkyl peroxide, diacyl peroxide, peroxyester, hydrogen peroxide, azobisisobutyronitrile, benzoyl peroxide and other organic peroxides can be used appropriately. When a chain transfer agent is used, for example, mercaptans, terpinolenes, α-methylstyrene dimer and the like can be used.

[0136] When the component (A) is produced by bulk polymerization or suspension polymerization, the polymerization initiator, chain transfer agent, and the like described in the solution polymerization can be used.

[0137] The amount of the monomer remaining in the component (A) obtained by the above-mentioned polymerization methods is usually 10,000 ppm or less, preferably 5,000 ppm or less.

[0138] The component (A) obtained by polymerizing a vinyl monomer (b1) in the presence of a rubber polymer (a) includes a copolymer in which a vinyl monomer (b1) is grafted onto the rubber polymer (a), and an ungrafted component (a (co)polymer of the vinyl monomer (b1)) which is not grafted onto the rubber polymer (a).

[0139] The grafting rate of the rubber-reinforced styrene resin (A) is preferably adjusted to usually 5 to 100% by mass, preferably 10 to 90% by mass, more preferably 15 to 85% by mass, and particularly preferably 20 to 80% by mass. The grafting rate can be changed according to various factors such as the type and amount of the polymerization initiator, the type and amount of the chain transfer agent, the polymerization method, the contact time between the vinyl monomer (b1) and the rubber polymer (a) during polymerization, the type of the rubber polymer (a), and the polymerization temperature. Generally, in the direction of increasing the grafting rate, the component dissolved in the hot cyclohexane by the component (A) is reduced, but if the soluble component is not present, the foaming property of the thermoplastic resin composition of the present invention is deteriorated.

[0140] The grafting ratio can be calculated by the following formula (15).

[0141] Grafting rate (mass %) = {(TS) / S} × 100 (15)

[0142] In formula (15), T is the mass (g) of the insoluble component obtained by placing 1 g of the rubber-reinforced styrene resin (A) in 20 ml of acetone, shaking it for 2 hours using a shaker, and then centrifuging it for 60 minutes using a centrifuge (rotation speed: 23,000 rpm) to separate the insoluble component from the soluble component. S is the mass (g) of the rubber polymer (a) contained in 1 g of the rubber-reinforced styrene resin (A).

[0143] When only an aromatic vinyl compound is used as the vinyl monomer (b1), methyl ethyl ketone is used in place of acetone for measurement.

[0144] The intrinsic viscosity [η] (measured at 30° C. using methyl ethyl ketone as a solvent) of the acetone-soluble component of the rubber-reinforced styrene resin (A) is usually 0.15 to 1.2 dl / g, preferably 0.2 to 1.0 dl / g, and more preferably 0.2 to 0.8 dl / g.

[0145] The average particle size of the grafted rubber polymer particles dispersed in the rubber-reinforced styrene resin (A) is usually 50 to 3,000 nm, preferably 40 to 2,5000 nm, and particularly preferably 50 to 2,000 nm. If the rubber particle size is less than 50 nm, the impact resistance tends to deteriorate; if it is greater than 3,000 nm, the surface appearance of the molded product tends to deteriorate.

[0146] By making the refractive index of the copolymer of the rubber polymer (a) and the vinyl monomer (b1) substantially the same, and / or making the particle size of the dispersed rubber polymer (a) substantially below the wavelength of visible light (generally below 1,500 nm), a transparent component (A) can be obtained. These transparent resins can also be used as the component (A) of the present invention.

[0147] The component (A) may be used alone or as a mixture of two or more components having different copolymer compositions, physical properties, etc.

[0148] [Component (B): Styrene resin (B)]

[0149] Component (B) is a styrene resin (B) obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and other vinyl monomers (b2) copolymerizable with the aromatic vinyl compound. The vinyl monomer (b2) may be a single aromatic vinyl compound or a mixture of an aromatic vinyl compound and other vinyl monomers copolymerizable with the aromatic vinyl compound. As the aromatic vinyl compound and other vinyl monomers copolymerizable with the aromatic vinyl compound used herein, all of the substances described in the above component (A) can be used. The vinyl monomer (b2) may be the same as or different from the above vinyl monomer (b1).

[0150] The content of monomers other than aromatic vinyl compounds in the vinyl monomer (b2) is usually 80% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less, when the total amount of the vinyl monomer (b2) is 100% by mass.

[0151] Preferred component (B) is a styrene homopolymer, a styrene-acrylonitrile copolymer, a styrene-methyl methacrylate copolymer, a styrene-acrylonitrile-methyl methacrylate copolymer, a styrene-maleimide compound copolymer, and a copolymer thereof with the above-mentioned unsaturated compound having a functional group.

[0152] The component (B) can be produced by the known polymerization methods described in the production method of the component (A), such as emulsion polymerization, bulk polymerization, solution polymerization, suspension polymerization, and a combination thereof.

[0153] The weight average molecular weight of the styrene resin (B) is usually 40,000 to 300,000, preferably 60,000 to 150,000. When the weight average molecular weight of the styrene resin (B) is within the above range, mechanical strength and moldability are further improved.

[0154] The weight average molecular weight of the styrene resin (B) is a value converted into standard polystyrene measured by gel permeation chromatography (GPC).

[0155] The component (B) may be used alone or as a mixture of two or more components having different copolymer compositions, physical properties, etc.

[0156] [Component (C): aromatic polycarbonate resin (C)]

[0157] As the aromatic polycarbonate resin (C), any resin obtained by a known polymerization method such as an interfacial polycondensation method of a dihydroxyaryl compound and phosgene, or a transesterification reaction (melt polycondensation) of a dihydroxyaryl compound and a carbonate compound such as diphenyl carbonate can be used.

[0158] Examples of the dihydroxyaryl compound include bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxyphenyl ether, 4,4'-dihydroxyphenyl sulfide, 4,4'-dihydroxyphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone, hydroquinone, and resorcinol. Examples include hydroxyaryloxy-terminated polyorganosiloxanes (see, for example, U.S. Patent No. 3,419,634). These compounds may be used alone or in combination of two or more. Among these, 2,2-bis(4-hydroxyphenylpropane (bisphenol A) is preferred.

[0159] The viscosity average molecular weight of the polycarbonate resin (C) is preferably 12,000 to 40,000, more preferably 15,000 to 35,000, and particularly preferably 18,000 to 30,000. If the molecular weight is high, the mechanical strength of the obtained foamed product increases, but the fluidity decreases, uniform cells cannot be obtained, and the appearance of the foamed product tends to decrease. As component (C), two or more aromatic polycarbonate resins (C) with different molecular weights can also be used.

[0160] The viscosity average molecular weight of the aromatic polycarbonate resin (C) can be generally calculated by inserting the specific viscosity (ηsp) measured at 20°C at a concentration of 0.7 g / 100 ml (dichloromethane) using dichloromethane as a solvent into the following formula (17).

[0161] Viscosity average molecular weight = ([η] × 8130) 1.205 (17)

[0162] Here, [η] = [(ηsp × 1.12 + 1) 1 / 2 -1] / 0.56C. C represents concentration.

[0163] The aromatic polycarbonate resin (C) obtained by interfacial polycondensation sometimes contains various chlorine compounds. The chlorine compounds may have an adverse effect on the durability of the thermoplastic resin composition of the present invention. Therefore, the chlorine compound content of the aromatic polycarbonate resin (C) is usually 300 ppm or less, preferably 100 ppm or less in terms of chlorine atoms.

[0164] [Contents of components (A) to (C)]

[0165] In the foam molding thermoplastic resin composition of the present invention, the content of component (A) is 1 to 20 parts by mass, preferably 3 to 18 parts by mass, and more preferably 5 to 15 parts by mass in 100 parts by mass of the total of components (A) to (C).

[0166] If the content of the component (A) is less than 1 part by mass, the impact strength decreases, and if it is more than 20 parts by mass, the moldability decreases.

[0167] In the foam molding thermoplastic resin composition of the present invention, the content of component (B) is 0 to 50 parts by mass, preferably 0 to 40 parts by mass, and more preferably 0 to 30 parts by mass in 100 parts by mass of the total of components (A) to (C).

[0168] In order to impart various functionalities to the thermoplastic resin composition of the present invention by changing the copolymerization components of the styrene resin (B), or to improve compatibility with other resins, component (B) may be used as required. If the content of component (B) is higher than 50 parts by mass, the foamability is impaired and the appearance of the obtained foamed molded product deteriorates.

[0169] In particular, it is preferred that the component (B) is blended so that the content of the rubber polymer (a) is 3 to 50 mass % in 100 mass % of the total of the components (A) and (B), because the balance between mechanical strength and fluidity is good.

[0170] In the foam molding thermoplastic resin composition of the present invention, the content of component (C) is 40 to 90 parts by mass, preferably 45 to 85 parts by mass, more preferably 50 to 80 parts by mass, based on 100 parts by mass of the total of components (A) to (C).

[0171] If the content of the component (C) is less than 40 parts by mass, it is difficult to obtain a foamed molded product having a uniform cell diameter. If it is greater than 90 parts by mass, the appearance of the obtained foamed molded product is deteriorated.

[0172] [Component (D): high molecular weight resin (D)]

[0173] The thermoplastic resin composition for foam molding of the present invention is characterized in that, in addition to the above-mentioned components (A) to (C), it also contains a high molecular weight resin (D) different from these components (A) to (C) and having a weight average molecular weight of 2,000,000 or more. The thermoplastic resin composition for foam molding of the present invention can solve the problem of the present invention by containing the high molecular weight resin (D) in a predetermined ratio.

[0174] As long as the weight average molecular weight of the high molecular weight resin (D) of component (D) is 2 million or more, there is no particular limitation on the type of resin, and preferably a thermoplastic resin. For example, there can be mentioned a (co)polymerized resin containing a structural unit derived from an aromatic vinyl compound (hereinafter referred to as "resin (D1)"), a (co)polymerized resin containing a structural unit derived from a (meth)acrylic acid alkyl ester compound having an alkyl group with 1 to 4 carbon atoms (hereinafter referred to as "resin (D2)"), a (co)polymerized resin of an α-olefin having 2 to 6 carbon atoms (hereinafter referred to as "resin (D3)"), polytetrafluoroethylene, polycarbonate, etc. Among these, resin (D1) and resin (D2) are preferred.

[0175] If the weight average molecular weight of the high molecular weight resin (D) is less than 2 million, the problem of the present invention cannot be solved, and the improvement of the appearance of the foamed molded product, the miniaturization and homogenization of the foaming pores cannot be achieved. From these aspects, the weight average molecular weight of the high molecular weight resin (D) is preferably more than 2.5 million, more preferably more than 3 million. If the weight average molecular weight of the high molecular weight resin (D) is too large, the thermoplastic resin composition for foam molding of the present invention is uneven, so the weight average molecular weight of the high molecular weight resin (D) is preferably less than 7 million, more preferably less than 5 million.

[0176] The weight average molecular weight of the high molecular weight resin (D) can be measured by gel permeation chromatography (GPC) using standard polystyrene and dimethylformamide as a solvent.

[0177] In the component (D), the aromatic vinyl compound forming the resin (D1) includes the aromatic vinyl compounds exemplified in the components (A) and (B). Among them, styrene and α-methylstyrene are preferred.

[0178] The resin (D1) may have structural units derived from other polymerizable compounds other than aromatic vinyl compounds. For example, it may have structural units derived from vinyl cyanide compounds, (meth)acrylate compounds, maleimide compounds, acid anhydrides, and vinyl compounds having functional groups such as hydroxyl, amino, epoxy, amide, carboxyl, and oxazoline. Other structural units may include one alone or a combination of two or more.

[0179] As the other polymerizable compound, various vinyl monomers exemplified in the above components (A) and (B) may also be mentioned.

[0180] As the vinyl cyanide compound, acrylonitrile is preferred.

[0181] As the (meth)acrylate compound, methyl methacrylate and n-butyl acrylate are preferred.

[0182] As the maleimide compound, N-phenylmaleimide and N-cyclohexylmaleimide are preferred.

[0183] As the acid anhydride, maleic anhydride is preferred.

[0184] As the vinyl compound containing a hydroxyl group, 2-hydroxyethyl methacrylate is preferred.

[0185] As the epoxy group-containing vinyl compound, glycidyl methacrylate is preferred.

[0186] As the amide group-containing vinyl compound, acrylamide is preferred.

[0187] As resin (D1), from the aspect of the molding processability of the thermoplastic resin composition for foam molding of the present invention, it is preferably a styrene copolymer containing an aromatic vinyl compound unit and a cyanide vinyl compound unit. The styrene copolymer may be a binary copolymer, or a ternary copolymer, a tetrapolymer, etc. further containing other structural units.

[0188] When the resin (D1) has the following structure, a foamed molded product having a high expansion ratio, and having an excellent balance between molded appearance and heat resistance can be obtained without reducing molding processability.

[0189] When the resin (D1) is a binary copolymer obtained by using an aromatic vinyl compound and a cyanide vinyl compound, the content ratio of the aromatic vinyl compound unit and the cyanide vinyl compound unit is preferably 50 to 95% by mass and 5 to 50% by mass, respectively, when the total of the aromatic vinyl compound unit and the cyanide vinyl compound unit is 100% by mass, more preferably 55 to 85% by mass and 15 to 45% by mass, and further preferably 65 to 75% by mass and 25 to 35% by mass. If the content of the cyanide vinyl compound unit is too much, the heat resistance of the obtained foamed product is reduced, and the foamed product may be colored; if it is too little, the ductility may be reduced.

[0190] When the resin (D1) contains other structural units in addition to the aromatic vinyl compound unit and the cyanide vinyl compound unit, the upper limit of the amount of the polymerizable compound forming the other structural units is preferably 50% by mass, more preferably 25% by mass, relative to 100% by mass of the total monomer components containing the aromatic vinyl compound and the cyanide vinyl compound. However, the lower limit is usually 16% by mass. If the above amount exceeds 50% by mass, the processability of the thermoplastic resin composition for foam molding tends to decrease.

[0191] When the resin (D1) is composed of an aromatic vinyl compound unit, a vinyl cyanide compound unit and other structural units, the proportions thereof are preferably 55 to 85 mass %, 15 to 45 mass % and 0 to 20 mass % respectively based on 100 mass % of the total of these structural units.

[0192] The resin (D2) is a (co)polymer of an alkyl (meth)acrylate compound unit containing an alkyl group having 1 to 4 carbon atoms, and is preferably polymethyl methacrylate.

[0193] The resins (D1) and (D2) can be produced by the same method as the above-mentioned components (A) and (B).

[0194] The resin (D3) is a homopolymer or copolymer of an α-olefin having 2 to 6 carbon atoms, namely, ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, etc., and is preferably polyethylene.

[0195] In the foam molding thermoplastic resin composition of the present invention, the content of component (D) is 0.1 to 10 parts by mass, preferably 0.3 to 8 parts by mass, and more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of the total of components (A) to (C).

[0196] If the content of the component (D) is less than 0.1 parts by mass, the effect of the present invention by compounding the component (D) cannot be sufficiently obtained, while if it exceeds 10 parts by mass, moldability decreases.

[0197] In the thermoplastic resin composition of the present invention, the component (D) may be used alone or two or more components different in resin type, physical properties, etc. may be mixed.

[0198] [Ingredient (E): chemical foaming agent (E)]

[0199] The thermoplastic resin composition for foam molding of the present invention preferably further contains a chemical foaming agent (E) (hereinafter sometimes referred to as "component (E)").

[0200] The chemical foaming agent (E) is not particularly limited, but since the thermoplastic resin composition of the present invention contains the aromatic polycarbonate resin (C), an amine foaming agent that degrades the aromatic polycarbonate resin (C) is not preferred. Preferred chemical foaming agents (E) include, for example, thermal decomposition-type inorganic foaming agents (such as sodium bicarbonate) that generate carbon dioxide upon decomposition, thermal decomposition-type foaming agents that generate nitrogen upon decomposition, and known thermal decomposition-type foaming compounds such as 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH), azobisisobutyronitrile, p-toluenesulfonylhydrazide, and 5-phenyltetrazole.

[0201] In order to obtain the desired expansion ratio, the content of the chemical foaming agent (E) is appropriately selected according to the type of chemical foaming agent (E) and resin used. Relative to a total of 100 parts by mass of components (A) to (C), the chemical foaming agent (E) is usually 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass, and more preferably 0.3 to 3 parts by mass. When the content of the chemical foaming agent (E) is less than 0.1 parts by mass, the content of the chemical foaming agent (E) is too small, and it is difficult to make the pore size of each foam uniform. When the content of the chemical foaming agent (E) is greater than 5 parts by mass, the content of the chemical foaming agent (E) is too much, and mold contamination occurs due to the residue of the chemical foaming agent (E), making it difficult to obtain a foamed molded product with excellent appearance.

[0202] [Component (F): Inorganic filler (F)]

[0203] The thermoplastic resin composition for foam molding of the present invention may be mixed with an inorganic filler (F) (hereinafter sometimes referred to as "component (F)") as needed. By mixing the inorganic filler (F), a foam molded product having fine and uniform foaming cells can be stably obtained. In addition, the rigidity, heat resistance and dimensional stability of the foam molded product can be improved.

[0204] Specific examples of the inorganic filler (F) used in the present invention include inorganic compound powders such as talc, wollastonite, calcium carbonate, mica, silica, and titanium dioxide, and glass fibers. In the present invention, talc is particularly preferred from the viewpoint of improving foamability and rigidity.

[0205] Talc is generally known as hydrous magnesium silicate (4SiO2·3MgO·H2O), and is a mineral containing about 60% by mass of SiO2 and about 30% by mass of MgO as main components. Surface-treated talc may be used.

[0206] When an inorganic filler (F) is added, the content of the inorganic filler (F) in the thermoplastic resin composition of the present invention is preferably 0.1 to 20 parts by mass, more preferably 3 to 15 parts by mass, and even more preferably 5 to 10 parts by mass, relative to 100 parts by mass of the total of components (A) to (C). By adding the inorganic filler (F) in such a ratio, the rigidity, heat resistance and dimensional stability of the obtained foamed molded product can be improved.

[0207] The particle size of the inorganic filler (F) is not particularly limited, but is preferably 0.5 to 50 μm, particularly preferably 2 to 20 μm, based on the central particle size of the volume cumulative particle size measured by laser diffraction method or the like, i.e., the 50% average particle size (hereinafter also referred to as "D50"). If the particle size is less than 0.5 μm, it is difficult to obtain the effect as a nucleating agent, and the foaming pore size increases, which is not preferred. If the particle size is greater than 50 μm, the foaming pores become coarse and small in number, and the strength and appearance of the foamed molded product deteriorate, which is not preferred.

[0208] [Other ingredients]

[0209] <Heat aging resistance>

[0210] The thermoplastic resin composition of the present invention may be mixed with a heat aging inhibitor. Examples of the heat aging inhibitor include phenolic, phosphorus, and sulfur-based agents, and preferably a mixture of phenolic, phosphorus, and sulfur-based agents. When the three mixed systems are used as heat aging inhibitors, the effect of maintaining tensile elongation when exposed to high temperatures for a long time can be obtained.

[0211] Among the heat aging inhibitors, examples of phenolic agents include 2,6-di-tert-butylphenol derivatives, 2-methyl-6-tert-butylphenol derivatives, octadecyl 3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4'-butylene-bis(6-tert-butyl-m-cresol), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2[1-(2-hydroxy-3,5-di-tert-pentylphenyl)-ethyl]-4,6-di-tert-pentylphenyl acrylate, and 2-tert-butyl-6(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate.

[0212] Examples of the phosphorus-based phosphite include tris(2,4-di-tert-butylphenyl)phosphite, cycloneopentanatetraylbis(2,4-di-tert-butylphenylphosphite), distearylpentaerythritol diphosphite, sodium dihydrogen phosphate, and disodium monohydrogen phosphate.

[0213] Examples of the sulfur-based compounds include didodecyl 3,3'-thiodipropionate, dioctadecyl 3,3'-thiodipropionate, pentaerythritol-tetrakis(3-lauryl propionate), and dilauryl 3,3'-thiodipropionate.

[0214] The content of the heat aging inhibitor in the thermoplastic resin composition of the present invention is usually 0 to 5% by mass, preferably 0 to 3% by mass. In the thermoplastic resin composition of the present invention, by adding the heat aging inhibitor, the heat aging characteristics of the rubber reinforced styrene resin (A) and the styrene resin (B) other than the aromatic polycarbonate resin (C) can be improved, but in the aromatic polycarbonate resin (C), the heat aging inhibitor sometimes acts as a catalyst to promote hydrolysis, and tends to inhibit deterioration when the heat aging inhibitor is not added. In view of these opposite effects, if the above-mentioned heat aging inhibitor is added with 5% by mass as the upper limit, the best heat aging resistance effect can be obtained.

[0215] <Other additives>

[0216] The thermoplastic resin composition of the present invention may be mixed with known additives such as weathering agents, lubricants, colorants, flame retardants, flame retardant aids, antistatic agents, silicone oils, etc. Among them, as weathering agents, benzotriazole series, triazine series, benzophenone series, etc. are preferred. As lubricants, ethylene bis stearamide, hydrogenated castor oil, etc. are preferred. As colorants, carbon black, red iron oxide, etc. can be cited. As antistatic agents, polyethers, sulfonates with alkyl groups, etc. can be cited.

[0217] <Other resins>

[0218] In the thermoplastic resin composition of the present invention, other thermoplastic resins other than components (A) to (D) may be mixed within a range that does not impair the performance of the purpose of the present invention, for example, within a range of 20 parts by mass or less in a total of 100 parts by mass of components (A) to (D) and other resins. As thermoplastic resins that can be mixed in the thermoplastic resin composition of the present invention, rubber reinforced styrene resins (which do not include component (A)), polyolefin resins, vinyl chloride resins, acrylic resins, polyester resins, polyamide resins, polyacetal resins, polyphenylene ether resins, polyarylene sulfide resins, etc. can be cited. These thermoplastic resins can be used alone or in combination of two or more.

[0219] [Production of Thermoplastic Resin Composition for Foam Molding]

[0220] The thermoplastic resin composition for foam molding of the present invention can be produced by kneading the components using various extruders, Banbury mixers, kneaders, rolls, and the like.

[0221] For example, pellets of the thermoplastic resin composition for foam molding of the present invention can be obtained by kneading components (A) to (D) and chemical foaming agents (E), inorganic fillers (F), and other additives used as needed. Specifically, a method in which components (A) to (D) and other additives used as needed are melted using a twin-screw extruder can be cited. The heating temperature during the melt kneading can be appropriately selected according to the ratio of the thermoplastic resin composition for foam molding, and is usually 220 to 260°C.

[0222] As a method for mixing the chemical foaming agent (E) into the molten plastic resin, the following method is preferably used: after dry mixing the pellets of the thermoplastic resin composition and the pellets of the foaming agent masterbatch, the pellets are supplied to a molding machine, and the resin is plasticized in the molding machine to be foamed in the mold. In addition, a physical foaming agent can also be used in combination. As a physical foaming agent, specifically, propane, butane, water, carbon dioxide, etc. can be cited.

[0223] [Foam molding products]

[0224] The foam-molded article of the present invention is obtained by foam-molding the thermoplastic resin composition for foam molding of the present invention.

[0225] As a method for molding the foam-molded article of the present invention using the thermoplastic resin composition for foam molding of the present invention, a known method such as injection foam molding and extrusion foam molding can be used.

[0226] In the injection foam molding method, a foamed molded product can be obtained by a so-called core-retracting injection molding method, in which the thermoplastic resin composition of the present invention is injected into a molding cavity space formed in a mold of an injection molding machine, and immediately or after a predetermined time, the movable mold or the movable core provided in the movable mold is retracted to a predetermined position at a predetermined speed to expand the molding cavity space and foaming is performed. The temperature of the injection molding mold is usually much lower than the temperature of the thermoplastic resin composition during injection, so that a dense outer skin layer that is hardly foamed is formed on the surface of the foamed molded product formed in contact with the molding cavity surface.

[0227] The foam molded product of the present invention can also be formed integrally in a manner of contacting the surface of a substrate made of resin or the like. Such a laminate can be formed by pre-arranging the substrate in a molding cavity space and injecting the thermoplastic resin composition for foam molding of the present invention onto its surface. In addition, an injection molding machine equipped with two injection units can be used, first injecting a resin as a substrate to form a substrate, then retreating the movable core in the movable mold to form a molding cavity space for injecting the thermoplastic resin composition for foam molding of the present invention, then injecting the thermoplastic resin composition for foam molding of the present invention, then retreating the movable core further to expand the molding cavity space for foaming, and making a laminated product with a foam molding layer stacked on the surface of the substrate.

[0228] In the injection foam molding of the present invention, the retreat speed of the movable mold or the retreat speed of the movable mold core provided in the movable mold, i.e., the above-mentioned "mold opening speed" is preferably 0.05 to 20 mm / sec. The mold opening speed is more preferably 0.1 to 10 mm / sec. By using such a mold opening speed, a moderately fine and uniform foamed molded product with an average pore size of 50 to 500 μm can be produced.

[0229] If the mold opening speed is less than 0.05 mm / sec, foaming is insufficient due to cooling, and unevenness may occur on the surface. If the mold opening speed is greater than 20 mm / sec, the pore diameter increases, and an uneven foamed product may be produced.

[0230] The temperature of the injected thermoplastic resin composition for foam molding is preferably 200 to 280° C., more preferably 220 to 270° C. If the temperature is lower than 200° C., the fluidity of the thermoplastic resin composition for foam molding is insufficient, and poor filling may occur, especially at the end portion. If the temperature is higher than 280° C., thermal degradation may occur depending on the composition of the thermoplastic resin composition for foam molding.

[0231] The mold temperature is preferably 20 to 80° C., particularly preferably 30 to 70° C. If the mold temperature is lower than 20° C., the thermoplastic resin composition for foam molding in contact with the inner surface of the mold is rapidly cooled, and a uniform foam molded product cannot be formed, and poor filling may occur at the end. If the mold temperature is higher than 80° C., a uniform outer skin layer may not be formed in the portion formed by contacting the surface of the molding cavity of the foam molded product, which is not preferred.

[0232] The time from the injection of the thermoplastic resin composition for foam molding until the movable mold or the movable mold core provided in the movable mold starts to retreat (mold retreat delay time) varies depending on the mold opening speed, but is preferably less than 3 seconds, and may also start retreating immediately after the injection is completed. The mold retreat delay time is preferably 0.1 to 2.5 seconds, particularly preferably 0.1 to 1.5 seconds. If the mold retreat delay time is longer than 3 seconds, a uniform foamed molded product may not be produced due to the progress of cooling.

[0233] The amount of mold retreat can be set according to the specified foaming ratio, and there is no limitation on it. Especially in the casing of the equipment, it is preferred to retreat the mold, that is, open the mold, in such a way that the final thickness of the foamed product is 1.1 to 3.0 times the initial thickness of the raw material filled in the molding cavity space in the mold. If this thickness ratio is used as the foaming ratio, the foaming ratio is preferably 1.1 to 3 times, and more preferably 1.5 to 2 times. Considering that there are many foamed products with a thickness of 5 to 30 mm, especially 5 to 25 mm, the amount of mold retreat is usually 2.5 to 30 mm.

[0234] The cooling time depends on the size of the foamed product or the cooling method. The temperature of the foamed product during demolding can be reduced to about 40 to 80°C. The cooling time is usually 30 seconds or more, and 100 seconds is sufficient even for large products.

[0235] In the method for molding a foamed molded article of the present invention, a fabric or a film may be inserted into a mold during injection filling.

[0236] The foamed molded product of the present invention has a fine foamed cell structure, and is a foamed molded product with uniform foamed cell size and excellent mechanical properties regardless of the location of the foamed molded product. Specifically, the average diameter of the foamed cell diameter is preferably 50 to 500 μm, more preferably 70 to 450 μm, and further preferably 100 to 400 μm, and the foamed cell diameter is preferably uniform and the particle size distribution is narrow. It is particularly preferred that the foamed molded product has a uniform foamed cell diameter of 400 μm or less in most cases.

[0237] The foamed molded article of the present invention can further have a desired expansion ratio of 1.01 to 3.0 times, preferably 1.1 to 2.7 times, more preferably 1.5 to 2.5 times.

[0238] The shape of the foamed molded article of the present invention can be selected according to the purpose, application, etc., and may be in the form of a plate (sheet), a cylinder, a semi-cylindrical shape, a rod, a string, a block, or the like.

[0239] [use]

[0240] The foamed molded article of the present invention can be used as the following components: display panels, concrete panels, roof insulation materials, tatami cores, sliding doors, wood substitute materials for modular kitchens; civil engineering and construction related materials such as bathtub lids and workbench boards; interior and exterior vehicle related materials such as side moldings, sound absorbing materials, bumpers, door handles, operation boxes, ceiling materials, columns, lower instrument panel trim panels, fairing side trims, center sockets, door linings, ashtrays, footrests, steering column covers, lower inserts, lower door handle panels, wheel covers, spoilers, etc.; daily sundries such as containers, trays, and decorative boxes; electrical and electronic components such as the housings of televisions, video recorders, air conditioners, parabolic antennas, and outdoor air conditioner units; sports goods such as floating boards and protective gear; interior and exterior decoration materials for houses and offices such as walls, floors, casings, furniture, decorative boards, partitions, lattice windows, fences, eaves, exterior wall panels, and carports; casings, cushioning materials, reinforcing materials, insulation materials, core materials, plywood substitutes, etc. for toys and gaming machines.

[0241] In addition, the foamed molded article of the present invention can be used, according to the intended use, as an article integrated or compounded with other molded articles, components, etc.

[0242] Examples

[0243] Examples and comparative examples are given below to more specifically illustrate the present invention. The present invention is not limited by any of the following examples as long as the gist is not exceeded.

[0244] Hereinafter, "parts" means "parts by mass", and "%" means "% by mass".

[0245] [Raw Materials]

[0246] In the following examples and comparative examples, the raw materials of the thermoplastic resin composition used are the resin components manufactured by the following method and the following commercially available products.

[0247] [Component (A): Manufacture of Rubber-Reinforced Styrene-Based Resin (A)]

[0248] <Manufacture of ABS Resin (Butadiene-Based Rubber Polymer / Styrene / Acrylonitrile Copolymer) (A-1)>

[0249] In a nitrogen stream, polybutadiene [manufactured by JSR Corporation, "BR51", high cis type, Mooney viscosity (ML 1+4, 33 at 100 °C, 15 parts with a gel content of 0%, 64 parts of styrene, 21 parts of acrylonitrile, and 140 parts of toluene. The internal temperature was raised to 75 °C, and the contents of the autoclave were stirred for 1 hour to form a homogeneous solution. Subsequently, 0.45 parts of tert-butyl peroxyisopropyl monocarbonate was added, and the internal temperature was further raised. After reaching 100 °C, while maintaining this temperature, the stirring speed was set to 100 rpm for the polymerization reaction.

[0250] After the start of the polymerization reaction, the internal temperature was raised to 120 °C starting from the 4th hour, and the reaction was further carried out for 2 hours while maintaining this temperature, and then the reaction was terminated. After cooling the internal temperature to 100 °C, 0.2 parts of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added. The polymerization conversion rate was 95%. The reaction mixture was withdrawn from the autoclave, and the unreacted substances and solvents were distilled off by steam distillation. Using an extruder with a vacuum exhaust port, the barrel temperature was adjusted to 220 °C and the vacuum degree was adjusted to 770 mmHg to substantially remove the volatile components, and pellets were made to obtain ABS resin (A-1).

[0251] The polymerization conversion rate of ABS resin (A-1) was 91%, the grafting rate was 68%, the intrinsic viscosity [η] of the acetone-soluble component was 0.39 dl / g, the thermal cyclohexane solubility was 2%, and the weight-average molecular weight was 48,000.

[0252] <Manufacture of ASA resin (acrylic rubber / styrene / acrylonitrile copolymer) (A-2)>

[0253] In a nitrogen stream, 160 parts of ion-exchanged water, 1 part of sodium dodecylbenzenesulfonate, 0.002 parts of cumene hydroperoxide, 0.004 parts of tetrasodium ethylenediaminetetraacetate, 0.001 parts of ferrous sulfate heptahydrate, 10 parts of n-butyl acrylate, and 0.02 parts of allyl methacrylate were put into a glass flask equipped with a stirrer, and the temperature was raised with stirring. At the moment when 60 °C was reached, 0.75 parts (20% aqueous solution) of sodium formaldehyde sulfoxylate was added. The internal temperature was maintained at 60 °C. After 80 minutes, 40 parts of n-butyl acrylate, 0.65 parts of allyl methacrylate, 0.01 parts of cumene hydroperoxide, 0.3 parts of sodium dodecylbenzenesulfonate, and 7 parts of ion-exchanged water were continuously added over 180 minutes. After the addition was completed, the polymerization was continued for another 60 minutes. After 60 minutes, a part of the acrylic rubber emulsion was sampled for evaluation, and the results showed that the volume average particle size was 0.1 μm and the gel content was 6%.

[0254] Subsequently, 5.2 parts (4% aqueous solution) of sodium dodecylbenzenesulfonate and 3 parts (20% aqueous solution) of sodium formaldehyde sulfoxylate were added. Styrene (38 parts), acrylonitrile (12 parts), 0.2 part of tert-butyl hydroperoxide, 0.3 part of sodium dodecylbenzenesulfonate, and 20 parts of ion-exchanged water were continuously added over 5 hours. After the addition was completed, polymerization was further continued for 45 minutes. Then, 0.2 part of 2,2'-methylenebis(4-ethyl-6-tert-butylphenol) was added to terminate the polymerization. The polymerization conversion rate was 99%. The emulsion of the reaction product was coagulated with an aqueous magnesium sulfate solution, washed with water, and then dried to obtain an ASA resin (A-2).

[0255] The grafting rate of the ASA resin (A-2) was 65%, the intrinsic viscosity [η] of the acetone-soluble component was 0.38 dl / g, the thermal cyclohexane solubility was 5%, and the weight-average molecular weight was 47,000.

[0256] <Manufacture of AES resin (ethylene·propylene rubber polymer / styrene / acrylonitrile copolymer) (A-3)>

[0257] In a nitrogen stream, 30 parts of an ethylene·propylene rubber polymer [ethylene content 63%, non-conjugated diene component is dicyclopentadiene, iodine value 10, Mooney viscosity (ML 1+4 、100 °C) 33, gel content 0%], 45 parts of styrene, 25 parts of acrylonitrile, and 140 parts of toluene were charged into a stainless-steel autoclave equipped with a helical ribbon-type stirrer. The internal temperature was raised to 75 °C, and the contents of the autoclave were stirred for 1 hour to form a homogeneous solution. Subsequently, 0.45 part of tert-butyl peroxyisopropyl monocarbonate was added, and the internal temperature was further raised. After reaching 100 °C, the polymerization reaction was carried out while maintaining this temperature and setting the stirring speed at 100 rpm.

[0258] After the polymerization reaction started, the internal temperature was raised to 120 °C from the 4th hour, and the reaction was further continued for 2 hours while maintaining this temperature, and then the reaction was terminated. After cooling the internal temperature to 100 °C, 0.2 part of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added. The polymerization conversion rate was 95%. The reaction mixture was withdrawn from the autoclave, and unreacted substances and solvents were distilled off by steam distillation. The barrel temperature was adjusted to 220 °C and the vacuum degree was adjusted to 770 mmHg using an extruder with a vacuum exhaust port to substantially remove volatile components and form pellets, obtaining an AES resin (A-3).

[0259] The grafting rate of the AES resin (A-3) was 60%, the intrinsic viscosity [η] of the acetone-soluble component was 0.45 dl / g, the thermal cyclohexane solubility was 35%, and the weight-average molecular weight was 72,000.

[0260] [Component (B): Manufacture of styrene resin (B)]

[0261] <Manufacture of AS resin (styrene / acrylonitrile copolymer) (B-1)>

[0262] Two stainless steel autoclaves equipped with helical ribbons were connected. After purging with nitrogen, 75 parts of styrene, 25 parts of acrylonitrile, and 20 parts of toluene were continuously added to the first reaction vessel. A solution of 0.16 parts of tert-dodecyl mercaptan as a molecular weight regulator and 5 parts of toluene, and a solution of 0.1 part of 1,1'-azobis(cyclohexane-1-carbonitrile) as a polymerization initiator and 5 parts of toluene were continuously supplied. The polymerization temperature in the first vessel was controlled at 110 °C, the average residence time was 2.0 hours, and the polymerization conversion was 57%. The resulting polymer solution was continuously withdrawn by a pump installed outside the first reaction vessel in an amount equal to the supply amounts of styrene, acrylonitrile, toluene, the molecular weight regulator, and the polymerization initiator, and supplied to the second reaction vessel. The polymerization in the second reaction vessel was carried out at 130 °C, and the polymerization conversion was 75%. For the copolymer solution obtained from the second reaction vessel, devolatilization of unreacted monomers and solvents was directly carried out using an extruder with a twin-screw and three-stage vents to obtain AS resin (B-1) having an intrinsic viscosity [η] of 0.64 dl / g and a weight-average molecular weight of 122,000.

[0263] [Component (C): Aromatic polycarbonate resin (C)]

[0264] As the aromatic polycarbonate resin: PC resin (C-1), "NOVAREX 7022PJ" (viscosity-average molecular weight: 20,900) manufactured by Mitsubishi Engineering Plastics Corporation was used.

[0265] [Component (D): High molecular weight resin (D)]

[0266] As the high molecular weight resin (D), the following commercially available products were used.

[0267] (D-1): High molecular weight acrylonitrile / styrene copolymer "Blendex 869" (weight-average molecular weight: 3.8 million) manufactured by General Electric Specialty Chemicals

[0268] (D-2): High molecular weight acrylic resin "METABLEN (registered trademark) P-531A" (weight-average molecular weight: 4.5 million) manufactured by Mitsubishi Chemical Corporation

[0269] [Component (E): Chemical blowing agent (E)]

[0270] As the chemical foaming agent (E), a masterbatch (ADCA (azodicarbonamide) / ABS = 10 / 90 (mass ratio)) of "Polythlene EB106" manufactured by Eiwa Chemical Industry Co., Ltd. was used. The compounding amount of the chemical foaming agent was 0.35 parts by mass per 100 parts by mass of the resin component (the total of components (A) to (C)).

[0271] [Ingredient (F): Inorganic filler (F)>

[0272] (F-1): Micro ACE SG-200, a micronized talc manufactured by Nippon Talc Co., Ltd.

[0273] (D50 based on laser diffraction method: 1μm)

[0274] (F-2): Wollastonite "NYGLOS 4W" manufactured by IMERYS

[0275] (Average particle size based on electron microscope observation: 7 μm)

[0276] [Examples 1 to 12, Comparative Examples 1 to 4]

[0277] [Production of Thermoplastic Resin Composition for Foam Molding]

[0278] The raw materials shown in Tables 1 and 2 were mixed in the ratio shown in Table 1, blended with a Henschel mixer, and then extruded at 250° C. using a twin-screw extruder TEX44 manufactured by Nippon Steel Works, Ltd. to obtain thermoplastic resin pellets before foam molding.

[0279] [Injection Foam Molding]

[0280] As a foaming molding machine, a 110 (t) electric molding machine (J110AD) manufactured by Nippon Steel Works was used. The obtained thermoplastic resin pellets were dry-mixed with a foaming agent masterbatch (chemical foaming agent (E)), supplied to the foaming molding machine, and core-retracting injection foam molding was performed to obtain a foamed molded product (a plate-shaped product of 100 mm×100 mm×3.7 mm thickness) as a test piece for evaluation.

[0281] In the injection foam molding, the filling time was 1 second, the mold opening speed was 0.5 mm / second, the injection temperature was 250° C., the mold temperature was 80° C., the mold retreat delay time was 0 seconds, and the foaming ratio was 1.5 times.

[0282] [Evaluation of Foam Molded Products]

[0283] The obtained foamed molded products were evaluated as follows. The results are shown in Tables 1 and 2.

[0284] <Appearance Observation>

[0285] (Swirl pattern)

[0286] The outer surface of the foamed product was visually observed, and the degree of surface deterioration due to swirls was evaluated according to the following criteria.

[0287] ◎: There are no swirls at all, and the surface appearance is very excellent.

[0288] ○: Slightly visible swirls, but the surface appearance is good.

[0289] △: Swirls were observed and the surface appearance was slightly poor.

[0290] ×: The swirl pattern is noticeable and the surface appearance is poor.

[0291] (Surface bumps)

[0292] The outer surface of the foamed product was visually observed, and the degree of surface deterioration due to the occurrence of surface dents was evaluated according to the following criteria.

[0293] ◎: There are no surface dents at all, and the surface appearance is very excellent.

[0294] ○: Surface dents are slightly visible, but the surface appearance is good.

[0295] △: Surface dents were observed and the surface appearance was slightly poor.

[0296] ×: The surface has significant dents and the surface appearance is poor.

[0297] <Cross-section observation>

[0298] (Break the bubble)

[0299] The foamed product was cut in the thickness direction, the cross section was observed, and the degree of breakage of foamed cells and the degree of cell bonding due to breakage were evaluated according to the following criteria.

[0300] ◎: There is no breakage of cells or bonding of cells due to breakage, and the cells are uniform over the entire cross-section.

[0301] ○: Breakage of foamed cells and bonding of cells due to breakage are slightly observed, but the cells are relatively uniform over the entire cross-section.

[0302] △: Breakage of foamed cells and bonding of cells due to breakage were observed, and a small amount of cell non-uniformity existed in the cross section.

[0303] ×: Uneven cell portions due to breakage of foamed cells and bonding of cells due to breakage were observed at many locations on the cross section.

[0304] (Cell shape)

[0305] The foamed product was cut in the thickness direction, the cell shape of the cross section was observed, and the fineness of the cells was evaluated according to the following criteria.

[0306] ⊚: Fine foamed cells with a cell diameter of about 100 μm exist uniformly, and the cell shape is very excellent.

[0307] ○: Most of the cells are fine cells with a cell diameter of about 100 μm, and the cell shape is excellent.

[0308] △: There are a few foamed cells with a cell diameter of about 100 to 300 μm among the fine foamed cells with a cell diameter of about 100 μm, and the uniformity is slightly poor.

[0309] ×: The cell diameter of the foamed cells is 100 to 300 μm, which is uneven and has poor uniformity.

[0310]

[0311]

[0312] [Investigation]

[0313] As can be seen from Tables 1 and 2, in Examples 1 to 12 in which the high molecular weight resin (D) was blended in the foam-molding thermoplastic resin composition, excellent foam-molded products having good surface appearance and fine and uniform foam cell structures were obtained.

[0314] On the other hand, in Comparative Examples 1 to 3 in which the high molecular weight resin (D) was not compounded, the foamed cell structure was particularly poor.

[0315] In Comparative Example 4, a high molecular weight resin (D) was used, but since the amount of the aromatic polycarbonate resin (C) blended was small, the melt viscosity characteristics were unstable, resulting in a slightly inferior foam cell structure.

[0316] Although the present invention has been described in detail using specific embodiments, it will be apparent to one skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention.

[0317] This application is based on Japanese patent application 2021-026367 filed on February 22, 2021, the entire contents of which are incorporated by reference.

Claims

1. A thermoplastic resin composition for foam molding, comprising 1 to 20 parts by mass of the following component (A), 0 to 50 parts by mass of the following component (B), and 40 to 90 parts by mass of the following component (C), per 100 parts by mass in total, and further comprising 0.1 to 10 parts by mass of a high molecular weight resin (D) different from the components (A) to (C) and having a weight average molecular weight of 2.5 million to 7 million, based on 100 parts by mass in total of the components (A) to (C), Component (A): a rubber-reinforced styrene resin (A) prepared by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b1) copolymerizable with the aromatic vinyl compound in the presence of a rubber polymer (a); Component (B): a styrene resin (B) obtained by polymerizing an aromatic vinyl compound or an aromatic vinyl compound and another vinyl monomer (b2) copolymerizable with the aromatic vinyl compound; Component (C): aromatic polycarbonate resin (C).

2. The thermoplastic resin composition for foam molding according to claim 1, wherein The weight average molecular weight of the high molecular weight resin (D) is 2.5 million to 5 million.

3. The thermoplastic resin composition for foam molding according to claim 1 or 2, wherein The composition further contains 0.1 to 5 parts by mass of a chemical foaming agent (E) based on 100 parts by mass of the total of the components (A) to (C).

4. The thermoplastic resin composition for foam molding according to claim 1 or 2, wherein The inorganic filler (F) is further contained in an amount of 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the components (A) to (C).

5. The thermoplastic resin composition for foam molding according to claim 1 or 2, which is used for core-return type injection foam molding. 6 . A foam-molded product obtained by molding the thermoplastic resin composition for foam molding according to claim 1 . 7 . A foam-molded product, which is obtained by subjecting the thermoplastic resin composition for foam molding according to claim 1 to core-return type injection foam molding.

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