Masterbatch for foam molding and its use

Abstract

The present invention provides a masterbatch for foam molding and its use. The masterbatch can inhibit adhesion to molding equipment, has excellent dispersibility, and can produce highly foamed, lightweight, and aesthetically pleasing foamed molded articles. The masterbatch comprises a matrix resin and heat-expandable microspheres, wherein the matrix resin comprises EPDM, the content of the heat-expandable microspheres being greater than 300 parts by weight and less than 750 parts by weight per 100 parts by weight of the matrix resin, and having a Mooney viscosity (ML1+4) of 15 to 90 (at 100°C).

Description

Technical Field

[0001] The present invention relates to a masterbatch for foam molding and application thereof. Background Art

[0002] In the past, when carrying out the shaping of various foams such as extrusion foaming molding, injection foaming molding, shaping was carried out after mixing foaming compositions such as heat-expandable microsphere (also referred to as heat-expandable microcapsule), various chemical foaming agents in the resin particle that becomes base material, blocky rubber.But the foaming composition used herein is easy to scatter, even mixes with base material, during supplying to forming machine, resin particle and foaming composition are also easy to separate.Therefore, carry out the method for following making foam forming masterbatch, that is, base material and foaming composition are pre-mixed at the softening temperature of above-mentioned base material and in the temperature below the temperature that foaming composition decomposes, foams, make desired shape.

[0003] For example, Patent Document 1 proposes a masterbatch for foam molding containing a matrix resin that essentially contains an EPDM resin and 40 to 300 parts by weight of thermally expandable microcapsules per 100 parts by weight of the matrix resin.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6523576 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, when using the masterbatch described in Patent Document 1 for foam molding, a large amount of masterbatch must be added to obtain a molded article with a particularly high expansion ratio. This can cause the masterbatch to adhere to the screws and rollers within the molding equipment, resulting in uneven foaming. This can lead to unstable specific gravity of the molded article and require time-consuming cleaning of the equipment used to remove the attached material. Furthermore, the increased amount of masterbatch can lead to reduced surface quality and physical properties of the molded article and poor dispersion of the masterbatch for foam molding.

[0009] As described above, there has hitherto been no masterbatch for foam molding that can suppress adhesion to molding equipment, has excellent dispersibility, and can produce a highly foamed, lightweight, and excellent-looking foam molded article.

[0010] The present invention provides a masterbatch for foam molding, which can suppress adhesion to molding equipment, has excellent dispersibility, and can produce a highly foamed, lightweight, and excellent-looking foam molded product, and its use.

[0011] Means for solving problems

[0012] The present inventors have conducted intensive studies to solve the above problems and have found that a foam molding masterbatch containing specific amounts of a specific matrix resin and heat-expandable microspheres and exhibiting specific properties can solve the above problems, thereby completing the present invention.

[0013] That is, the present invention is a masterbatch for foam molding, which includes a matrix resin and heat-expandable microspheres, wherein the matrix resin includes EPDM, and the content of the heat-expandable microspheres is greater than 300 parts by weight and less than 750 parts by weight relative to 100 parts by weight of the matrix resin, and the Mooney viscosity ML1+4 (100°C) of the masterbatch for foam molding is 15 to 90.

[0014] In the foam molding masterbatch of the present invention, it is preferred that the EPDM have an ethylene content of 45 to 72% by weight.

[0015] In the foam molding masterbatch of the present invention, it is preferred that the diene content of the EPDM is 2.2 to 10.0% by weight.

[0016] In the masterbatch for foam molding of the present invention, it is preferred that the heat-expandable microspheres are formed of an outer shell comprising a thermoplastic resin and a foaming agent enclosed in the outer shell and vaporized by heating, and the thermoplastic resin is a polymer containing at least one polymerizable component selected from acrylonitrile, methacrylonitrile, and vinylidene chloride.

[0017] The method for manufacturing a masterbatch for foam molding of the present invention includes a step of mixing a material 1 comprising a matrix resin and a liquid compound with a material 2 comprising heat-expandable microspheres, wherein the matrix resin comprises EPDM, and the content of the heat-expandable microspheres is greater than 300 parts by weight and less than 750 parts by weight relative to 100 parts by weight of the matrix resin, and the Mooney viscosity ML1+4 (100°C) of the masterbatch for foam molding is 15 to 90.

[0018] The resin composition of the present invention comprises the above-mentioned masterbatch for foam molding and a matrix resin.

[0019] The foamed molded article of the present invention is a molded product of the above-mentioned resin composition.

[0020] Effects of the Invention

[0021] The foam molding masterbatch of the present invention can suppress adhesion to molding equipment, has excellent dispersibility, and can produce a highly foamed, lightweight, and excellent-looking foamed molded article.

[0022] The method for producing a foam molding masterbatch of the present invention can produce a foam molding masterbatch that is less likely to adhere to molding equipment and has excellent dispersibility, and can produce a highly foamed, lightweight, and excellent-looking foamed molded article.

[0023] Since the resin composition of the present invention contains the above-mentioned masterbatch for foam molding, it is possible to produce a foamed molded article that has little foaming unevenness, is highly foamed, is lightweight, and has an excellent appearance.

[0024] The foamed molded article of the present invention has little foaming unevenness, is highly foamed, is lightweight, and has an excellent appearance. DETAILED DESCRIPTION

[0025] The foam molding masterbatch of the present invention (hereinafter sometimes referred to as simply a masterbatch) comprises a matrix resin and heat-expandable microspheres.

[0026] 〔Matrix resin〕

[0027] The matrix resin contained in the foam molding masterbatch of the present invention must contain EPDM (ethylene-propylene-diene copolymer rubber). This provides excellent dispersibility and enables the production of a foamed molded article with minimal foaming unevenness.

[0028] The ethylene content of EPDM (the content of the ethylene component constituting EPDM) is not particularly limited, but is preferably 45 to 72% by weight. If the ethylene content is 45% by weight or more, there is a tendency for foaming unevenness to decrease. On the other hand, if the ethylene content is 72% by weight or less, there is a tendency for dispersibility to improve. The upper limit of the ethylene content of EPDM is more preferably 70% by weight, further preferably 67% by weight, and particularly preferably 65% by weight. On the other hand, the lower limit of the ethylene content of EPDM is more preferably 47% by weight, further preferably 50% by weight, and particularly preferably 55% by weight.

[0029] The propylene content of EPDM (the content of the propylene component constituting EPDM) is not particularly limited, but is preferably 20 to 45% by weight.

[0030] The diene contained in EPDM (diene component constituting EPDM) is not particularly limited, but examples thereof include 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadiene, 4-ethylidene-1,7-undecadiene, and 1,4-hexadiene. The dienes include 1,4-hexadiene, 5-methylene-2-norbornene, 5-n-propylidene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene, 5-isobutenyl-2-norbornene, dicyclopentadiene, and norbornadiene. Among the above dienes, 1,4-hexadiene, 5-ethylidene-2-norbornene, and dicyclopentadiene are preferred.

[0031] The diene content of EPDM (the content of the diene components constituting EPDM) is not particularly limited, but is preferably 2.2 to 10% by weight. When the diene content of EPDM is within this range, moldability tends to improve. The upper limit of the diene content of EPDM is more preferably 9.5% by weight, further preferably 9% by weight, and particularly preferably 8% by weight. On the other hand, the lower limit of the diene content of EPDM is more preferably 3% by weight, further preferably 3.5% by weight, and particularly preferably 4.5% by weight.

[0032] The ratio of the ethylene content to the diene content in EPDM (ethylene content:diene content) is not particularly limited, but is preferably 80:20 to 98:2, and more preferably 85:15 to 96:4.

[0033] The Mooney viscosity ML1+4 (100°C) of EPDM (hereinafter sometimes referred to as the Mooney viscosity of EPDM) is not particularly limited, but is preferably 5 to 80. If the Mooney viscosity of EPDM is 5 or more, the production stability of the masterbatch for foam molding can be improved. On the other hand, if the Mooney viscosity of EPDM is 80 or less, the handling properties of the masterbatch for foam molding can be improved. The upper limit of the Mooney viscosity of EPDM is more preferably 75, further preferably 70, and particularly preferably 65. On the other hand, the lower limit of the Mooney viscosity of EPDM is more preferably 10, further preferably 15, and particularly preferably 20.

[0034] Note that the "Mooney viscosity ML1+4 (100°C)" referred to herein is a numerical value indicating viscosity, measured according to JIS K-6300. In ML1+4 (100°C), "M" refers to the Mooney viscosity, "L" refers to the rotor shape, "1+4" refers to the preheating time of 1 minute and the rotor rotation time of 4 minutes, and "(100°C)" refers to the preheating temperature.

[0035] The matrix resin may be composed of EPDM or may contain other resins in addition to EPDM. The EPDM content in the matrix resin is not particularly limited, but is preferably 75 to 100% by weight, more preferably 85 to 100% by weight, and even more preferably 90 to 100% by weight or more.

[0036] When the matrix resin includes other resins other than EPDM, other resins, such as rubber components, include rubbers such as ethylene propylene rubber (EPR), natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR), acrylic rubber, polyurethane rubber, and silicone rubber; thermoplastic resins such as polyvinyl chloride, polypropylene, modified polypropylene, polypropylene oxide, polyethylene, low-density polyethylene, high-density polyethylene, modified polyethylene, ethylene-vinyl acetate copolymer (EVA), polystyrene, polybutylene terephthalate, nylon, polycarbonate, and polyethylene terephthalate; ionomer resins such as ethylene ionomers, urethane ionomers, styrene ionomers, and fluorine ionomers; and thermoplastic elastomers such as olefin elastomers, styrene elastomers, and polyester elastomers. These other resins may be used alone or in combination of two or more.

[0037] The specific gravity of the matrix resin is not particularly limited, but is preferably 0.80 to 1.0. When the specific gravity of the matrix resin is within this range, the specific gravity of the resulting molded article tends to be uniform. The upper limit of the specific gravity of the matrix resin is more preferably 0.98, and particularly preferably 0.96. On the other hand, the lower limit of the specific gravity of the matrix resin is more preferably 0.82, and particularly preferably 0.85.

[0038] The content of the matrix resin in the foam molding masterbatch of the present invention is not particularly limited, but is preferably 20 to 65% by weight. If the matrix resin content is less than 20% by weight, the masterbatch may not be obtained. On the other hand, if the matrix resin content exceeds 65% by weight, it may adhere to the molding equipment.

[0039] [Heat-expandable microspheres]

[0040] The foam molding masterbatch of the present invention contains heat-expandable microspheres.

[0041] Heat-expandable microspheres are formed by an outer shell (shell) comprising a thermoplastic resin and a foaming agent (core) enclosed in the outer shell and gasified by heating. Heat-expandable microspheres form a core-shell structure, and heat-expandable microspheres show thermal expansibility (property that the microspheres as a whole expand due to heating) as a microsphere.

[0042] The thermoplastic resin that constitutes the shell of heat-expandable microsphere is the polymer obtained by polymerizing polymerizable components.Polymerizable components is to take monomeric component as essential component, the composition that sometimes comprises crosslinking agent.Monomeric component refers to the monomer with 1 (free radical) polymerizable carbon-carbon double bond, is the composition that can addition polymerization.In addition, crosslinking agent refers to the monomer with at least 2 (free radical) polymerizable carbon-carbon double bonds, is the composition that can crosslinked structure be imported into thermoplastic resin.

[0043] The monomer component is not particularly limited, but examples thereof include nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; vinyl halide monomers such as vinyl chloride; vinylidene halide monomers such as vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, and chloromaleic acid; anhydrides of unsaturated dicarboxylic acids; monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; and carboxyl group-containing monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, (Meth)acrylate monomers such as 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate; (meth)acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide; maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; styrene monomers such as styrene and α-methylstyrene; ethylenically unsaturated monoolefin monomers such as ethylene, propylene, and isobutylene; vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone; N-vinyl monomers such as N-vinylcarbazole and N-vinylpyrrolidone; and vinyl naphthalene salts. Carboxyl group-containing monomers may have some or all of the carboxyl groups neutralized during or after polymerization.

[0044] Acrylic acid and methacrylic acid are sometimes collectively referred to as (meth)acrylic acid, and acrylates and methacrylates are sometimes collectively referred to as (meth)acrylates. Furthermore, (meth)acrylates refer to acrylates or methacrylates, and (meth)acrylic acids refer to acrylic acids or methacrylic acids. These monomer components may be used alone or in combination of two or more.

[0045] If the monomer component includes a nitrile monomer and vinylidene halide, the gas barrier properties of the shell of the heat-expandable microspheres can be improved, which is preferred. In addition, if the monomer component includes at least one selected from acrylonitrile, methacrylonitrile and vinylidene chloride, the gas barrier properties can be further improved.

[0046] In the case where monomer component (polymerizable component) comprises at least one selected from acrylonitrile (AN), methacrylonitrile (MAN) and vinylidene chloride, the ratio shared by the total amount of acrylonitrile, methacrylonitrile and vinylidene chloride in polymerizable component is not particularly limited, but is preferably 30~100 weight %. If the total amount of acrylonitrile, methacrylonitrile and vinylidene chloride is less than 30 weight %, the situation that the gas barrier property of the shell of heat-expandable microspheres is reduced is arranged. The upper limit of the ratio shared by the total amount of acrylonitrile, methacrylonitrile and vinylidene chloride in polymerizable component is more preferably 99.9 weight %, more preferably 99.5 weight %, particularly preferably 98.5 weight %. On the other hand, the lower limit of the ratio shared by the total amount of acrylonitrile, methacrylonitrile and vinylidene chloride in polymerizable component is more preferably 40 weight %, more preferably 50 weight %, particularly preferably 55 weight %.

[0047] When the monomer components include AN and MAN, the weight ratio of AN to MAN is not particularly limited, but preferably AN:MAN = 1:99 to 100:0, more preferably AN:MAN = 5:95 to 95:5, further preferably AN:MAN = 10:90 to 90:10, particularly preferably 30:70 to 85:15, and most preferably AN:MAN = 50:50 to 80:20. When the weight ratio of AN to MAN is within this range, the shell of the heat-expandable microspheres has a dense structure, and the gas barrier properties tend to be improved.

[0048] If the monomer component includes a carboxyl group-containing monomer, the heat-expandable microspheres obtained have excellent heat resistance and solvent resistance, so it is preferred. As the carboxyl group-containing monomer, acrylic acid and methacrylic acid are preferred because they are easy to obtain and improve heat resistance.

[0049] When the monomer component contains a monomer containing a carboxyl group, the weight ratio of the monomer containing a carboxyl group in the polymerizable component is not particularly limited, but is preferably 10 to 70% by weight. If the weight ratio of the monomer containing a carboxyl group is less than 10% by weight, there is a situation where sufficient heat resistance cannot be achieved. On the other hand, if the weight ratio of the monomer containing a carboxyl group is greater than 70% by weight, there is a situation where gas barrier properties are reduced. The upper limit of the weight ratio of the monomer containing a carboxyl group in the polymerizable component is more preferably 60% by weight, further preferably 50% by weight, particularly preferably 45% by weight, and most preferably 40% by weight. On the other hand, the lower limit of the weight ratio of the monomer containing a carboxyl group in the polymerizable component is more preferably 15% by weight, further preferably 20% by weight, particularly preferably 25% by weight, and most preferably 30% by weight.

[0050] When the monomer components include a nitrile monomer and a carboxyl group-containing monomer, the total weight ratio of the carboxyl group-containing monomer and the nitrile monomer relative to the monomer components is not particularly limited, but is preferably 50% by weight or more, more preferably 60% by weight or more, further preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more.

[0051] In addition, the ratio of the monomer that contains carboxyl in the total of nitrile monomer and carboxyl monomer is not particularly limited, yet is preferably 10~70 wt %.If the ratio that contains carboxyl monomer is less than 10 wt %, then there is the raising of thermotolerance, solvent resistance and becomes insufficient situation.On the other hand, if the ratio that contains carboxyl monomer is greater than 70 wt %, then there is the situation that the expansion performance of heat-expandable microspheres goes down.The upper limit of the ratio that contains carboxyl monomer in the total of nitrile monomer and carboxyl monomer is more preferably 60 wt %, further preferably 50 wt %, particularly preferably 45 wt %, most preferably 40 wt %.On the other hand, the lower limit of the ratio that contains carboxyl monomer is more preferably 15 wt %, further preferably 20 wt %, particularly preferably 25 wt %, most preferably 30 wt %.

[0052] In the case that monomer component comprises the monomer that contains carboxyl, heat-expandable microsphere can be carried out surface treatment by having with the reactive compound of carboxyl.Be not particularly limited as having with the reactive compound of carboxyl, yet for example can enumerate organic compound, epoxy resin, silane coupling agent etc. with metal.

[0053] When the monomer component contains a (meth)acrylate monomer or a styrene monomer, thermal expansion characteristics can be easily controlled. When the polymerizable component contains a (meth)acrylamide monomer as a monomer component, heat resistance can be improved.

[0054] When the monomer component contains at least one selected from the group consisting of an acrylate monomer, a (meth)acrylamide monomer, and a styrene monomer, the total weight ratio of the acrylate monomer, the (meth)acrylamide monomer, and the styrene monomer in the polymerizable component is not particularly limited, but is preferably 50% by weight or less, more preferably 35% by weight or less, and particularly preferably 10% by weight or less. If the total weight ratio of the acrylate monomer, the (meth)acrylamide monomer, and the styrene monomer exceeds 50% by weight, heat resistance may be reduced.

[0055] As described above, the polymerizable component may contain a crosslinking agent. By using a crosslinking agent for polymerization, the heat-expandable microspheres obtained can suppress the reduction of the retention rate (inner inclusion retention rate) of the foaming agent contained therein during thermal expansion, thereby enabling efficient thermal expansion.

[0056] The crosslinking agent is not particularly limited, but examples thereof include aromatic divinyl compounds such as divinylbenzene; allyl methacrylate, triacryloyl formal, triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, polypropylene glycol #400 di(meth)acrylate, polypropylene glycol #700 di(meth)acrylate, tripropylene glycol di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, polypropylene glycol #400 di(meth)acrylate, polypropylene glycol #700 di(meth)acrylate, tripropylene glycol di(meth)acrylate, PEG#60 ... Di(meth)acrylate compounds such as methylolpropane trimethacrylate, EO-modified trimethylolpropane trimethacrylate, glycerol dimethacrylate, dimethylol-tricyclodecane diacrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, tris(2-acryloyloxyethyl)isocyanurate, triallyl isocyanurate, triallyl cyanurate, triglycidyl isocyanurate, polybutylene glycol dimethacrylate, EO-modified bisphenol A dimethacrylate, neopentyl glycol dimethacrylate, nonanediol diacrylate, trimethylolpropane tri(meth)acrylate, and 3-methyl-1,5-pentanediol diacrylate. These crosslinking agents may be used alone or in combination of two or more.

[0057] There is no particular limitation on the amount of the cross-linking agent, and although it may be omitted, the amount of the cross-linking agent is preferably 0.01 to 6 parts by weight, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 1 part by weight relative to 100 parts by weight of the monomer component, taking into account the degree of cross-linking, the internal retention rate of the foaming agent enclosed in the shell, the heat resistance, and the thermal expansion.

[0058] The foaming agent constituting the heat-expandable microspheres is not particularly limited as long as it is a substance that vaporizes upon heating. Examples of the foaming agent include hydrocarbons having 3 to 13 carbon atoms, such as propane, (iso)butane, (iso)pentane, (iso)hexane, (iso)heptane, (iso)octane, (iso)nonane, (iso)decane, (iso)undecane, (iso)dodecane, and (iso)tridecane; hydrocarbons having a carbon number greater than 13 and less than 20, such as (iso)hexadecane and (iso)eicosane; hydrocarbons such as seudocumene, petroleum ether, and petroleum fractions such as normal alkanes and isoalkanes having an initial boiling point of 150 to 260°C and / or a distillation range of 70 to 360°C; halogenated products thereof; fluorine-containing compounds such as hydrofluoroethers; tetraalkylsilanes; compounds that generate gas upon thermal decomposition upon heating, and the like. These foaming agents may be used alone or in combination of two or more. The foaming agent may be any of linear, branched, and alicyclic, and an aliphatic foaming agent is preferred.

[0059] Blowing agent is the material that gasifies because of heating, if inner bag has the material of the boiling point below the softening point of thermoplastic resin as blowing agent, then can produce the vapor pressure that is enough to expand under the expansion temperature condition of heat-expandable microsphere, can give high expansion ratio, thereby preferred.In above-mentioned blowing agent, if comprise the hydrocarbon below carbon number 8, then heat-expandable microsphere can have high expansion performance, thereby preferred.

[0060] Alternatively, a substance having a boiling point higher than the softening point of the thermoplastic resin may be incorporated as a foaming agent. When incorporating a substance having a boiling point higher than the softening point of the thermoplastic resin as a foaming agent, the proportion of the substance having a boiling point higher than the softening point of the thermoplastic resin in the foaming agent is not particularly limited, but is preferably 95% by weight or less, more preferably 80% by weight or less, even more preferably 70% by weight or less, particularly preferably 65% by weight or less, even more preferably 50% by weight or less, and most preferably less than 30% by weight. If the proportion of the substance having a boiling point higher than the softening point of the thermoplastic resin exceeds 95% by weight, the maximum expansion temperature may increase, resulting in a decrease in the expansion ratio. However, a proportion greater than 95% by weight is acceptable.

[0061] The inner encapsulation rate of the foaming agent is defined by the percentage of the weight of the foaming agent encapsulated in the heat-expandable microspheres relative to the weight of the heat-expandable microspheres. There is no particular limitation on the inner encapsulation rate of the foaming agent, and the inner encapsulation rate can be appropriately determined according to the purposes used, but is preferably 1 to 50%, more preferably 2 to 40%, and particularly preferably 3 to 30%. If the inner encapsulation rate is less than 1%, the effect of the foaming agent cannot be obtained. On the other hand, if the inner encapsulation rate is greater than 50%, the thickness of the shell of the heat-expandable microspheres becomes thinner, thus becoming the cause of air leakage, and there is a situation in which heat resistance reduces and high expansion performance cannot be obtained.

[0062] The average particle size of the heat-expandable microspheres is not particularly limited, but is preferably 1 to 200 μm. If the average particle size of the heat-expandable microspheres is within the above range, there is a trend to obtain a lightweight, well-looking molded body. The upper limit of the average particle size of the heat-expandable microspheres is more preferably 100 μm, further preferably 75 μm, particularly preferably 50 μm, and most preferably 45 μm. On the other hand, the lower limit of the average particle size of the heat-expandable microspheres is more preferably 3 μm, further preferably 5 μm, particularly preferably 8 μm, and most preferably 10 μm.

[0063] It should be noted that the average particle size of the heat-expandable microspheres was obtained by the method described in Examples.

[0064] The coefficient of variation CV of the particle size distribution of the heat-expandable microspheres is not particularly limited, but is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less.

[0065] The coefficient of variation CV was calculated using the following calculation formulas (1) and (2).

[0066] [Mathematical formula 1]

[0067] CV=(s / <x>)×100(%)···(1)

[0068]

[0069] (Where s is the standard deviation of particle size, <x> is the average particle size, xi is the size of the i-th particle, and n is the number of particles.)

[0070] The expansion starting temperature (T s ) is not particularly limited, but is preferably 60 to 250°C. s) is lower than 60 ℃, then the problem of time stability of heat-expandable microspheres is generated, and when used for resin molding, there is a situation that fluctuation is generated in the expansion ratio. On the other hand, if the expansion starting temperature is higher than 250 ℃, then the heat resistance is too high, and there is a situation that sufficient expansion performance cannot be obtained. The upper limit of the expansion starting temperature of heat-expandable microspheres is more preferably 230 ℃, further preferably 200 ℃, particularly preferably 180 ℃, and most preferably 170 ℃. On the other hand, the lower limit of the expansion starting temperature of heat-expandable microspheres is more preferably 70 ℃, further preferably 80 ℃, particularly preferably 90 ℃, and most preferably 100 ℃.

[0071] The maximum expansion temperature of heat-expandable microspheres (T max ) is not particularly limited, but is preferably 80 to 350°C. If the maximum expansion temperature is lower than 80°C, it may be difficult to use for resin molding. On the other hand, if the maximum expansion temperature is higher than 350°C, the heat resistance is too high and sufficient expansion performance may not be obtained. The upper limit of the maximum expansion temperature of the heat-expandable microspheres is more preferably 280°C, further preferably 250°C, particularly preferably 230°C, and most preferably 210°C. On the other hand, the lower limit of the maximum expansion temperature of the heat-expandable microspheres is more preferably 90°C, further preferably 100°C, particularly preferably 110°C, and most preferably 120°C.

[0072] The expansion starting temperature and the maximum expansion temperature of the heat-expandable microspheres were obtained by the method described in Examples.

[0073] The circularity of heat-expandable microsphere is not particularly limited, yet is preferably below 0.995.If the circularity of heat-expandable microsphere is greater than 0.995, then there is heat-expandable microsphere and can't be evenly dispersed in the situation in the matrix resin.The upper limit of the circularity of heat-expandable microsphere is more preferably 0.985, further preferably 0.975, particularly preferably 0.965.On the other hand, the lower limit of the circularity of heat-expandable microsphere is 0.50.

[0074] Heat-expandable microspheres can generally be obtained by a production method comprising the steps of polymerizing the polymerizable component in an aqueous dispersion medium in which an oily mixture containing the polymerizable component and a foaming agent described above is dispersed, preferably in the presence of a polymerization initiator.

[0075] The polymerization initiator is not particularly limited, but generally used peroxides, azo compounds, and the like can be mentioned.

[0076] Examples of the peroxide include peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and dibenzyl peroxydicarbonate; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 2,2-bis(tert-butylperoxy)butane; hydroperoxides such as cumene hydroperoxide and tert-butyl hydroperoxide; dialkyl peroxides such as dicumyl peroxide and di-tert-butyl peroxide; and peroxyesters such as tert-hexyl peroxypivalate and tert-butyl peroxyisobutyrate.

[0077] Examples of the azo compound include 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-methylbutyronitrile), and 1,1′-azobis(cyclohexane-1-carbonitrile).

[0078] The weight ratio of the polymerization initiator is not particularly limited, but is preferably 0.05 to 10 weight %, more preferably 0.1 to 8 weight %, and most preferably 0.2 to 5 weight % relative to 100 parts by weight of the polymerizable component.

[0079] The aqueous dispersion medium used to disperse the oily mixture is a medium primarily composed of water, such as ion-exchanged water, and may further contain an alcohol such as methanol, ethanol, or propanol, or a hydrophilic organic solvent such as acetone. Hydrophilicity, as used herein, refers to the ability to be fully miscible in water. The amount of the aqueous dispersion medium used is not particularly limited, but is preferably 100 to 1000 parts by weight per 100 parts by weight of the polymerizable component.

[0080] The aqueous dispersion medium may further contain an electrolyte. Examples of the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium carbonate. One or more of these electrolytes may be used. The content of the electrolyte is not particularly limited, but preferably contains 0.1 to 50 parts by weight relative to 100 parts by weight of the aqueous dispersion medium.

[0081] The aqueous dispersion medium may contain at least one water-soluble compound selected from the group consisting of water-soluble 1,1-substituted compounds, potassium dichromate, alkali metal nitrites, metal (III) halides, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble vitamin B compounds, and water-soluble phosphonates, wherein the water-soluble 1,1-substituted compound has a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylate group, and a phosphonate group and a heteroatom are bonded to the same carbon atom. It should be noted that water-soluble in the present invention means that at least 1 g of the compound is soluble in 100 g of water.

[0082] The amount of the water-soluble compound contained in the aqueous dispersion medium is not particularly limited, but is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 0.1 part by weight, and particularly preferably 0.001 to 0.05 part by weight, relative to 100 parts by weight of the polymerizable component.

[0083] The aqueous dispersion medium may contain a dispersion stabilizer and a dispersion stabilization auxiliary in addition to the electrolyte and the water-soluble compound.

[0084] The dispersion stabilizer is not particularly limited, but examples thereof include calcium phosphate, magnesium pyrophosphate obtained by double decomposition production, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, etc. These dispersion stabilizers may be used alone or in combination of two or more.

[0085] The amount of the dispersion stabilizer to be added is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the polymerizable component.

[0086] The dispersion stabilization auxiliary agent is not particularly limited, but examples thereof include polymeric dispersion stabilization auxiliary agents, surfactants such as cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants. These dispersion stabilization auxiliary agents may be used alone or in combination of two or more.

[0087] The aqueous dispersion medium is preferably prepared by mixing a water-soluble compound with water (ion-exchanged water) and, if necessary, a dispersion stabilizer and / or a dispersion stabilization auxiliary. The pH of the aqueous dispersion medium during polymerization can be appropriately determined depending on the types of the water-soluble compound, dispersion stabilizer, and dispersion stabilization auxiliary.

[0088] In the method for producing heat-expandable microspheres, polymerization can be carried out in the presence of sodium hydroxide, or in the presence of sodium hydroxide and zinc chloride.

[0089] Among the methods for producing heat-expandable microspheres, a method of suspending and dispersing an oily mixture in an aqueous dispersion medium so as to prepare spherical oil droplets of a predetermined particle size is preferred.

[0090] Examples of methods for suspending and dispersing the oily mixture include stirring methods using a homomixer (e.g., manufactured by Primix), methods using a static dispersing device such as a static mixer (e.g., manufactured by Noritake Engineering Co., Ltd.), membrane suspension methods, ultrasonic dispersion methods, and other general dispersion methods.

[0091] Then, by the dispersion liquid that oily mixture is scattered in the aqueous dispersion medium with the form of spherical oil droplet being heated, and begin suspension polymerization.In the polyreaction, preferably stirred dispersion liquid, this stirring for example lentamente and get final product with the degree of sedimentation of the heat-expandable microsphere that can prevent monomeric floating, polymerization.

[0092] The polymerization temperature can be freely set depending on the type of polymerization initiator, but is preferably controlled within the range of 30 to 100°C, more preferably 40 to 90°C. The reaction temperature is preferably maintained for approximately 1 to 20 hours. The initial polymerization pressure is not particularly limited, but is preferably within the range of 0 to 5 MPa, more preferably 0.1 to 3 MPa, in terms of gauge pressure.

[0093] Foam molding masterbatch of the present invention can comprise liquid compound.If comprise liquid compound, then can improve the dispersibility of heat-expandable microsphere, thereby preferably.In addition, if liquid compound does not make the thermoplastic resin dissolving or swelling of the shell constituting heat-expandable microsphere then preferably.

[0094] The liquid compound is not particularly limited, but examples thereof include plasticizers such as dibutyl phthalate, diisooctyl phthalate, diisononyl phthalate, dioctyl adipate, tricresyl phosphate, triethyl citrate, acetyl tributyl citrate, and octanol; nonionic surfactants; polyols such as alkylene glycol, polyalkylene glycol, and glycerol; process oils; silicone oils; liquid paraffin; naphthenic oils; aromatic oils; plant oils such as palm oil, soybean oil, rapeseed oil, sunflower oil, corn oil, and linseed oil; and oils and fats. These liquid compounds may be used alone or in combination of two or more.

[0095] The boiling point of the liquid compound is not particularly limited, but is preferably 80° C. to 300° C., more preferably 90° C. to 270° C., and particularly preferably 100° C. to 250° C. When the boiling point of the liquid compound is within the above range, volatilization during storage of the masterbatch tends to be suppressed.

[0096] The content of the liquid compound in the masterbatch for foam molding is not particularly limited, but is preferably 70 to 1000 parts by weight relative to 100 parts by weight of the matrix resin. If the content of the liquid compound is less than 70 parts by weight, the dispersibility of the heat-expandable microspheres may be reduced. On the other hand, if the content of the liquid compound is greater than 1000 parts by weight, the handling properties of the masterbatch may be reduced. The upper limit of the content of the liquid compound is more preferably 800 parts by weight or less, further preferably 600 parts by weight or less, and particularly preferably 500 parts by weight or less. The lower limit of the content of the liquid compound is preferably in the order of (1) greater than 100 parts by weight, (2) greater than 150 parts by weight, (3) greater than 200 parts by weight, (4) greater than 205 parts by weight, and (5) greater than 250 parts by weight (the larger the number in the brackets, the more preferred).

[0097] When the masterbatch for foam molding contains a liquid compound, oil-extended EPDM can be used as the EPDM contained in the matrix resin.

[0098] The foam molding masterbatch of the present invention may contain a lubricant. The lubricant is not particularly limited as long as it softens or melts at the temperature during masterbatch production or molding of the molded article. Examples thereof include fatty acid lubricants such as stearic acid, fatty acid amides such as stearic acid amide, esters such as butyl stearate, alcohols such as stearyl alcohol, and compounds or mixtures thereof, as well as metal soaps.

[0099] The foam molding masterbatch of the present invention may contain a chemical foaming agent. Examples of the chemical foaming agent include inorganic chemical foaming agents such as sodium bicarbonate, and organic chemical foaming agents such as azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, p,p'-oxybisbenzenesulfonylhydrazine, and p-toluenesulfonylhydrazine.

[0100] The masterbatch for foam molding of the present invention is not particularly limited as long as the effects of the present invention are not impaired, but may contain a stabilizer, a filler, a pigment, a liquid rubber, and the like.

[0101] Examples of the stabilizer include phenolic stabilizers such as pentaerythritol-tetrakis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]; phosphorus stabilizers such as tris(monononylphenyl)phosphite and tris(2,4-di-tert-butylphenyl)phosphite; and sulfur stabilizers such as dilauroyl dipropionate.

[0102] Examples of fillers include inorganic fillers such as calcium carbonate, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, talc, clay, glass beads, and glass microspheres; and organic fillers such as high styrene resins, coumarone-indene resins, phenolic resins, lignin, modified melamine resins, and petroleum resins.

[0103] Examples of the pigment include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, and carbon black; and organic pigments such as azo pigments, phthalocyanine pigments, quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, anthrapyrimidine pigments, anthraquinone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, perone pigments, dionepyrrolopyrrole pigments, quinonaphthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, and isoindoline pigments.

[0104] Examples of the liquid rubber include liquid polybutadiene and modified products thereof.

[0105] [Masterbatch for foam molding and its manufacturing method]

[0106] The foam molding masterbatch of the present invention comprises a matrix resin that essentially contains EPDM and heat-expandable microspheres. The content of the heat-expandable microspheres is greater than 300 parts by weight and less than 750 parts by weight based on 100 parts by weight of the matrix resin.

[0107] If the content of heat-expandable microsphere is below 300 weight parts, then masterbatch is attached to forming equipment.On the other hand, if the content of heat-expandable microsphere is greater than 750 weight parts, then the poor dispersibility of heat-expandable microsphere, can't obtain high-foamed formed body.The upper limit of the content of heat-expandable microsphere is preferably 730 weight parts, more preferably 700 weight parts, further preferably 680 weight parts, particularly preferably 650 weight parts, most preferably 600 weight parts.On the other hand, the lower limit of the content of heat-expandable microsphere is preferably 301 weight parts, more preferably 305 weight parts, further preferably 310 weight parts, particularly preferably 325 weight parts, most preferably 350 weight parts.

[0108] The Mooney viscosity ML1+4 (100°C) of the masterbatch for foam molding of the present invention is 15 to 90. If the Mooney viscosity of the masterbatch is outside the above range, the dispersibility of the masterbatch is poor, uneven foaming occurs, and the appearance of the resulting molded product is poor. The upper limit of the Mooney viscosity ML1+4 (100°C) of the masterbatch for foam molding is preferably 88, more preferably 85, further preferably 80, particularly preferably 75, and most preferably 70. On the other hand, the lower limit of the Mooney viscosity ML1+4 (100°C) of the masterbatch for foam molding is preferably 20, more preferably 25, further preferably 30, particularly preferably 35, and most preferably 40.

[0109] The specific gravity of the masterbatch for foam molding of the present invention is not particularly limited, but is preferably 0.60 to 1.5. If the specific gravity of the masterbatch is outside the above range, part of the heat-expandable microspheres will expand or be destroyed, and there may be a case where a lightweight molded body cannot be obtained. The upper limit of the specific gravity of the masterbatch is more preferably 1.3, further preferably 1.2, and particularly preferably 1.1. On the other hand, the lower limit of the specific gravity of the masterbatch is more preferably 0.65, further preferably 0.70, and particularly preferably 0.75. The specific gravity of the masterbatch for foam molding is obtained by the method described in the examples.

[0110] The expansion ratio of the masterbatch of the present invention is not particularly limited, but is preferably 5 to 150 times. If the expansion ratio of the masterbatch is less than 5 times, the expansion ratio of the resulting molded body becomes low, and there is a case where it does not become lightweight. On the other hand, if the expansion ratio of the masterbatch is greater than 150 times, the heat-expandable microspheres not only expand inside the molded body, but also expand to near its surface layer, so that the appearance is damaged. The upper limit of the expansion ratio of the masterbatch is more preferably 120 times, further preferably 100 times, and particularly preferably 80 times. On the other hand, the lower limit of the expansion ratio of the masterbatch is more preferably 10 times, further preferably 15 times, and particularly preferably 20 times. The expansion ratio of the masterbatch for foam molding is obtained by the method described in the examples.

[0111] The masterbatch for foam molding of the present invention may be in any of various shapes such as powder, granular, block, string, pellet, or sheet.

[0112] The present invention provides a method for producing a masterbatch for foam molding, comprising the steps of mixing a material 1 comprising a matrix resin and a liquid compound with a material 2 comprising heat-expandable microspheres, wherein the matrix resin comprises EPDM, the content of the heat-expandable microspheres being greater than 300 parts by weight and less than 750 parts by weight relative to 100 parts by weight of the matrix resin, and the Mooney viscosity ML1+4 (100° C.) of the masterbatch for foam molding being 15 to 90. This method can produce a masterbatch for foam molding that is capable of suppressing adhesion to molding equipment, exhibits excellent dispersibility, and can produce a highly foamed, lightweight, and aesthetically pleasing foamed molded article.

[0113] The matrix resin contained in the material 1 includes EPDM, and the aforementioned matrix resin was used. In addition, the aforementioned liquid compound was used as the liquid compound.

[0114] The content of the liquid compound contained in Material 1 may be the entire amount of the liquid compound that can be used, or may be a portion thereof. The content of the liquid compound contained in Material 1 is not particularly limited, but is preferably 40 to 1000 parts by weight relative to 100 parts by weight of the matrix resin. If the content of the liquid compound is less than 40 parts by weight, the dispersibility of the heat-expandable microspheres may be reduced when mixed with Material 2. On the other hand, if the content of the liquid compound is less than 1000 parts by weight, the yield of the masterbatch may be reduced. The upper limit of the content of the liquid compound is more preferably 800 parts by weight, further preferably 600 parts by weight, and particularly preferably 500 parts by weight. On the other hand, the lower limit of the content of the liquid compound is preferably in the order of (1) 80 parts by weight, (2) 100 parts by weight, (3) 150 parts by weight, (4) 180 parts by weight, and (5) 200 parts by weight (the larger the number in the brackets, the more preferred).

[0115] Furthermore, the material 1 may contain the aforementioned lubricant, chemical foaming agent, stabilizer, filler, pigment, liquid rubber, etc. in addition to the matrix resin and the liquid compound.

[0116] The method for producing the material 1 is not particularly limited, but an example thereof includes mixing (kneading) a matrix resin comprising EPDM having a predetermined Mooney viscosity with a liquid compound and, if necessary, the aforementioned lubricant. Furthermore, oil-extended EPDM may be used when producing the material 1.

[0117] When producing the material 1, for example, a mixer such as a roll, a kneader, a pressure kneader, or a Banbury mixer can be used. The temperature when obtaining the material 1 is preferably 50 to 100°C.

[0118] Material 2 comprises above-mentioned heat-expandable microsphere, can also comprise above-mentioned liquid compound, lubricant, chemical foaming agent, stabilizing agent, weighting agent, pigment, liquid rubber etc. beyond this.As heat-expandable microsphere, can use the wet powdered heat-expandable microsphere that comprises liquid things such as liquid compound.In addition, material 2 can not comprise matrix resin.

[0119] When producing the material 2, for example, a mixer such as a ribbon mixer, a counter rotor mixer, a Henschel mixer, a tumble mixer, a planetary mixer, a super mixer, a high-speed mixer, or an SV mixer can be used.

[0120] The shared part by weight of heat-expandable microsphere in material 2 is not particularly limited, yet is preferably more than 30 % by weight.If the shared part by weight of heat-expandable microsphere in material 2 is less than 30 % by weight, the situation that the manufacturing efficiency of masterbatch reduces is arranged.The upper limit of the shared part by weight of heat-expandable microsphere in material 2 is preferably 100 % by weight, more preferably 98 % by weight, further preferably 95 % by weight, particularly preferably 90 % by weight.On the other hand, the lower limit of the shared part by weight of heat-expandable microsphere in material 2 is more preferably 40 % by weight, further preferably 45 % by weight, particularly preferably 50 % by weight.

[0121] The method for producing a masterbatch for foam molding of the present invention includes a step of mixing material 1 and material 2. The step of mixing material 1 and material 2 may be performed by adding material 2 to material 1 or by adding material 1 to material 2. Furthermore, the above-mentioned mixer can be used in the step of mixing material 1 and material 2.

[0122] As the temperature when material 1 is mixed with material 2, if do not carry out under the temperature that is lower than the expansion starting temperature of heat-expandable microsphere, heat-expandable microsphere will expand.Usually, in order not to make heat-expandable microsphere expand, preferably carry out the manufacturing of masterbatch at the temperature (being preferably low temperature more than 5 ℃) that is lower than the expansion starting temperature.

[0123] In addition, the material 1 obtained in the above-mentioned process and the mixture of the material 2 can be made into a given shape using a roller, a granulator, an extruder, a pelletizer, etc. according to the use form of the masterbatch for foam molding. When the mixture is made into a masterbatch of a given shape, it is also the same as the above-mentioned process. Usually, in order not to expand the heat-expandable microspheres, it is best to manufacture the masterbatch at a temperature lower than the expansion starting temperature (preferably a temperature lower than 5° C. or more).

[0124] [Resin composition, foamed molded article, and method for producing the same]

[0125] A foamed molded article is obtained by molding a resin composition containing a masterbatch for foam molding and a matrix resin.

[0126] The matrix resin is not particularly limited, but examples thereof include polyvinyl chloride; polyvinylidene chloride; polyvinyl alcohol; ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-butyl (meth)acrylate copolymer and other ethylene copolymers; ionomers; polyolefin resins such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, polyisobutylene, polystyrene, and polyterpene; styrene copolymers such as styrene-acrylonitrile copolymer and styrene-butadiene-acrylonitrile copolymer; polyacetal; polymethyl methacrylate; cellulose acetate; polycarbonate; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as nylon 6 and nylon 66; thermoplastic polyurethane; tetrafluoroethylene; ethylene ionomers; Ionomer resins such as polyurethane, urethane ionomers, styrene ionomers, and fluorine ionomers; polyacetal; thermoplastic resins such as polyphenylene sulfide; thermoplastic elastomers such as polyurethane elastomers, styrene elastomers, olefin elastomers, polyamide elastomers, and polyester elastomers; bioplastics such as polylactic acid (PLA), cellulose acetate, PBS, PHA, and starch resin; rubbers such as EPDM (ethylene-propylene-diene copolymer rubber), ethylene-propylene rubber (EPR), natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR), acrylic rubber, polyurethane rubber, fluororubber, and silicone rubber, and the like, can be used alone or in combination of two or more.

[0127] The weight part shared for heat-expandable microsphere in resin combination is not particularly limited, yet is preferably 0.01~60 wt %.If the weight part of heat-expandable microsphere is less than 0.01 wt %, then the foaming molding of gained is arranged to be difficult to become the situation of lightweight.On the other hand, if the weight part of heat-expandable microsphere is greater than 60 wt %, though then the foaming molding of gained becomes lightweight, yet has the situation that mechanical strength significantly reduces.The upper limit of the weight part of heat-expandable microsphere is more preferably 50 wt %, more preferably 20 wt %, particularly preferably 10 wt %.The lower limit of the weight part of heat-expandable microsphere is more preferably 0.1 wt %, more preferably 0.5 wt %, particularly preferably 1 wt %.

[0128] There is no particular limitation on the weight ratio of the matrix resin in the resin composition, but it is preferably 40 to 99.99% by weight. If the weight ratio of the matrix resin is less than 40% by weight, although the resulting foaming molded body becomes lightweight, there is a situation where the mechanical strength is significantly reduced. On the other hand, if the weight ratio of the matrix resin is greater than 99.99% by weight, there is a situation where the resulting foaming molded body is difficult to become lightweight. The upper limit of the weight ratio of the matrix resin is more preferably 99.9% by weight, more preferably 99.5% by weight, and particularly preferably 99% by weight. The lower limit of the weight ratio of the matrix resin is more preferably 50% by weight, more preferably 80% by weight, and particularly preferably 90% by weight.

[0129] The resin composition of the present invention may contain the above-mentioned liquid compound, lubricant, stabilizer, lubricant, filler, pigment, liquid rubber, etc., in addition to the masterbatch for foam molding and the matrix resin, as needed.

[0130] As a molding method for the resin composition, various molding methods can be used, such as injection molding, extrusion molding, blow molding, calendar molding, press molding, vacuum molding, and kneading molding. In the case of injection molding, for example, there are the short shot method in which a portion of the resin material is added to a mold and then foamed, and the core-back method in which a mold is filled with the resin material and then expanded to the desired foaming position.

[0131] Furthermore, since the heat-expandable microspheres thermally expand during molding to obtain heat-expanded microspheres, that is, hollow particles, the foamed molded article contains the hollow particles.

[0132] There is no particular limitation on the average particle size of the hollow particles contained in the foaming molded article, but it is preferably 1 to 1000 μm. If the average particle size of the hollow particles is less than 1 μm, the lightweight effect may be insufficient. On the other hand, if the average particle size of the hollow particles is greater than 1000 μm, the strength of the foaming molded article may be reduced. The upper limit of the average particle size of the hollow particles contained in the foaming molded article is more preferably 500 μm, further preferably 300 μm, and particularly preferably 200 μm. On the other hand, the lower limit of the average particle size of the hollow particles contained in the foaming molded article is more preferably 2 μm, further preferably 5 μm, and particularly preferably 10 μm.

[0133] The expansion ratio (expansion ratio of foaming molded article) when utilizing the shaping of resin composition to obtain foaming molded article is not particularly limited, but is preferably 1.1 times or more, more preferably 1.2 to 5 times, particularly preferably 1.4 to 4 times, and most preferably 1.5 to 3 times. If the expansion ratio of foaming molded article is within the above range, there is a tendency to form a foaming molded article that is lightweight and has sufficient strength.

[0134] Examples of uses of the foamed molded article of the present invention include automotive components such as door moldings, instrument panels, windshield strips, glass runs, bumpers, and tires; building materials such as shoe soles, wood powder plastics, and flooring materials; and artificial cork.

[0135] Example

[0136] Below, the embodiment of foaming molding masterbatch of the present invention is specifically described.It should be noted that the present invention is not limited to these embodiments.In the following examples and comparative examples, as long as not particularly pointed out, so-called "parts" are exactly "parts by weight", and so-called "%" are exactly "% by weight".For the foaming masterbatch and the foaming molding etc. that are cited in the heat-expandable microspheres, embodiments and comparative examples of following manufacture example, measure physical property according to the essentials shown below, and then evaluate performance.Below, for the sake of simplicity, sometimes heat-expandable microspheres are referred to as "microballoons".

[0137] <Average Particle Size of Heat-Expandable Microspheres>

[0138] A MICROTRAC particle size distribution analyzer (Model 9320-HRA) manufactured by Nikkiso Co., Ltd. was used as a measuring apparatus, and the D50 value measured on a volume basis was defined as the average particle size.

[0139] <Expansion starting temperature (T s ) and maximum expansion temperature (T max ) determination>

[0140] As a measuring device, DMA (DMA Q800 type, TA instruments company system) is used. 0.5mg of heat-expandable microspheres are put into an aluminum cup with a diameter of 6.0mm (inner diameter 5.65mm) and a depth of 4.8mm, and an aluminum cover (diameter 5.6mm, thickness 0.1mm) is placed on the upper part of the heat-expandable microsphere layer to prepare a sample. The sample height is measured under a state where a pressurizer is applied with a force of 0.01N from above. Under a state where a pressurizer is applied with a force of 0.01N, the sample is heated from 20°C to 300°C at a heating rate of 10°C / min, and the displacement in the vertical direction of the pressurizer is measured. The displacement starting temperature in the positive direction is set as the expansion starting temperature (T s ), the maximum displacement (H m扒 ) is set as the maximum expansion temperature of the heat-expandable microspheres (T max ).

[0141] <Measurement of Specific Gravity of Foam Molding Masterbatch>

[0142] The specific gravity of the foam molding masterbatch was measured using a Shimadzu upper plate electronic analytical balance (AX200, manufactured by Shimadzu Corporation) in a solid specific gravity measurement mode.

[0143] <Measurement of Mooney Viscosity ML(1+4) at 100°C of Foam Molding Masterbatch>

[0144] The Mooney viscosity of the obtained masterbatch at 100° C. was measured using a Mooney viscometer (SMV-301, manufactured by Shimadzu Corporation) by a method in accordance with JIS-K6300.

[0145] <Evaluation of Dispersibility of Foam Molding Masterbatch>

[0146] Regarding the dispersibility of the masterbatch for foam molding, the masterbatch was placed in a mold with a thickness of 0.35 mm and a size of 70 mm. Using a desktop proofer (SA-302, manufactured by Tester Industrial Co., Ltd.), it was thinly stretched to a width of 10 mm × a length of 10 cm × a thickness of 0.35 mm, and the presence of agglomerates was visually confirmed.

[0147] The dispersibility of the foam molding masterbatch was determined based on the following evaluation criteria, and a value of Δ or greater was considered acceptable.

[0148] ⊚: No aggregates were confirmed.

[0149] ○: 1 to 3 aggregates were observed.

[0150] Δ: 4 to 5 aggregates were observed.

[0151] ×: Six or more aggregates were observed.

[0152] <Evaluation of Adhesion of Foam Molding Masterbatch to Equipment>

[0153] A Labo Plastomill (a single-screw extruder ME-25 manufactured by Toyo Seiki Co., Ltd.) and a T-die (lip width 150 mm, thickness 2 mm) were used. The set temperature of the extruder and T-die was set to 80°C, and the screw speed was set to 40 rpm. A foaming masterbatch prepared as square pellets (3-4 mm in width, 3-4 mm in length, and 3-4 mm in depth) was placed into the Labo Plastomill and extruded for 10 minutes to evaluate whether extrusion could be performed with a stable discharge rate without the masterbatch adhering to the screw below the hopper.

[0154] Adhesion of the foam molding masterbatch to the equipment was evaluated based on the following evaluation criteria, and a score of ○ or higher was considered acceptable.

[0155] ◎: The screw does not stick to the bottom of the hopper, and the discharge volume is stable.

[0156] ○: Although a very small amount of it adheres to the screw under the hopper, the discharge amount is stable.

[0157] ×: The screw attached to the bottom of the hopper stops discharging on the way.

[0158] <Measurement of Specific Gravity of Foamed Molded Article>

[0159] The specific gravity of the foamed molded article was measured using a Shimadzu upper plate electronic analytical balance (AX200, manufactured by Shimadzu Corporation) in a solid specific gravity measurement mode.

[0160] <Evaluation of Appearance of Foamed Molded Article>

[0161] The appearance of the foamed molded article was evaluated by measuring the surface roughness (Rz) of the molded article surface using a 3D shape measuring machine (VR-3000, manufactured by KEYENCE Corporation). The evaluation was based on the following criteria, and samples with a score of ◯ or higher were considered acceptable.

[0162] ◎: Rz<30μm

[0163] ○: 30μm<Rz<50μm

[0164] Δ: 50μm≤Rz≤100μm

[0165] ×: Rz>100μm

[0166] <Evaluation of Dispersibility of Foam Molded Article>

[0167] The dispersibility of the foamed molded article was evaluated by visually observing a cross section of the foamed molded article using an electron microscope (VE-8800, manufactured by KEYENCE Corporation), and judging was performed based on the following criteria.

[0168] ○: Bubbles are uniformly dispersed.

[0169] ×: The bubbles are not uniformly dispersed.

[0170] <Production Example 1>

[0171] To 600 g of ion-exchanged water were added 150 g of sodium chloride, 80 g of colloidal silica containing 20% by weight of active ingredient, 1.5 g of polyvinyl pyrrolidone, and 0.5 g of ethylenediaminetetraacetic acid tetrasodium salt. The pH of the resulting mixture was adjusted to 2.0 to 3.5 to prepare an aqueous dispersion medium.

[0172] Separately, 140 g of acrylonitrile, 56 g of methacrylonitrile, 2 g of methyl methacrylate, 2 g of PEG#200 diacrylate, 30 g of 2-methylpropane, 20 g of 2-methylbutane, and 3 g of 2,2'-azobis(2,4-dimethylvaleronitrile) were mixed to prepare an oily mixture.

[0173] Aqueous dispersion medium is mixed with oily mixture, the mixed solution of gained is dispersed with homomixer, prepares suspension.This suspension is transferred in the pressure reactor of capacity 1.5L and carries out nitrogen replacement after making reaction initial pressure be 0.3MPa, while stirring 60 ℃ of polymerizations 20 hours, the resultant of gained is filtered, dried, obtain heat-expandable microsphere 1 (microsphere 1).The physical property of the heat-expandable microsphere of gained is shown in Table 1.

[0174] <Production Examples 2 and 3>

[0175] In Production Examples 2 and 3, heat-expandable microspheres 2 and 3 (microspheres 2 and 3) were obtained in the same manner as in Production Example 1, except that the reaction conditions were changed as shown in Table 1. The physical properties were evaluated and are shown in Table 1.

[0176] [Table 1]

[0177]

[0178] <Example 1>

[0179] 200 parts by weight of EPDM1 (the amount of EPDM used is 100 parts by weight, and the amount of oil filling is 100 parts by weight), 150 parts by weight of PW-90 (processing oil, manufactured by Idemitsu Kosan Co., Ltd.), and 10 parts by weight of stearic acid were kneaded in a kneader until the material temperature reached 60°C to obtain Material 1. Microspheres 1 were added to the resulting Material 1 and kneaded in a kneader at 60°C for 3 minutes to obtain a mixture containing the matrix resin and heat-expandable microspheres. The resulting mixture was mixed in a roll mill at a roll temperature of 60°C, a roll speed of 20 rpm, and a roll gap of 1 cm for 3 minutes to produce a masterbatch for foam molding with a thickness of 1 cm. The resulting masterbatch for foam molding had a Mooney viscosity of 71 and a specific gravity of 0.89.

[0180] Then, a matrix composition was prepared in advance by mixing 100 parts by weight of EPDM (ethylene content 63% by weight, diene content 4.4% by weight), 250 parts by weight of heavy calcium carbonate, 64 parts by weight of paraffin oil, 15 parts by weight of stearic acid, 5 parts by weight of zinc oxide, 1 part by weight of carbon black, 1 part by weight of sulfur, and 4 parts by weight of a vulcanization accelerator.

[0181] 2 parts by weight of the obtained foaming masterbatch was mixed with 100 parts by weight of a pre-prepared matrix composition to obtain a resin composition. The obtained resin composition was supplied to the hopper of an extruder and extruded while being mixed to obtain a plate-shaped molded body. It should be noted that the extrusion temperature was set to 80°C. The plate-shaped molded body obtained by extrusion molding was vulcanized in a vulcanizing furnace under vulcanization conditions of 200°C × 5 minutes to produce a foamed molded body. The physical properties of the foamed molded body produced are shown in Table 2.

[0182] <Examples 2 to 12, Comparative Examples 1 to 4>

[0183] In Examples 2 to 8, a masterbatch for foam molding and a foam molded article were produced in the same manner as in Example 1, except that the compounding conditions in Example 1 were changed as shown in Table 2. The physical properties of each were measured and evaluated. The results are shown in Tables 2 and 3.

[0184] [Table 2]

[0185]

[0186] [Table 3]

[0187]

[0188] Table 4 shows the details of the raw materials used in Examples and Comparative Examples of the present invention.

[0189] [Table 4]

[0190]

[0191] It can be clearly seen from Tables 2 and 3 that the matrix resin comprises EPDM, the content of the above-mentioned heat-expandable microspheres is greater than 300 parts by weight and less than 750 parts by weight relative to 100 parts by weight of the matrix resin, and the Mooney viscosity ML1+4 (100°C) is 15 to 90. The masterbatch for foam molding of the embodiment can suppress adhesion to the molding equipment, has excellent dispersibility, and can produce highly foamed, lightweight and excellent-looking foamed moldings.

[0192] On the other hand, it can be seen that the masterbatch for foam molding of Comparative Examples 1 to 3, in which the amount of heat-expandable microspheres contained and the Mooney viscosity ML1+4 (100°C) are outside the above range, cannot solve at least one of the problems of the present invention, that is, it can inhibit adhesion to the molding equipment, has excellent dispersibility, and can produce highly foamed, lightweight and excellent-looking foamed molded products.

[0193] Furthermore, it was found that, in the method that does not include the step of mixing the material 1 and the material 2, a masterbatch could not be produced as in Comparative Example 4.

[0194] Industrial applicability

[0195] The foam molding masterbatch of the present invention can be used for foam molding such as injection molding, extrusion molding, and press molding, and can be used to produce foamed molded products having excellent sealing properties, sound insulation properties, heat insulation properties, heat insulating properties, sound absorbing properties, and the like.

Claims

1. A masterbatch for foam molding, comprising a matrix resin, heat-expandable microspheres and a liquid compound, The matrix resin comprises EPDM, and the content of the EPDM in the matrix resin is 90 wt% to 100 wt%. The heat-expandable microspheres are formed of an outer shell comprising a thermoplastic resin and a foaming agent enclosed in the outer shell and vaporized by heating. The thermoplastic resin is a polymer comprising at least one polymerizable component selected from acrylonitrile and methacrylonitrile, and the total amount of acrylonitrile and methacrylonitrile in the polymerizable component accounts for 50% to 100% by weight. The liquid compound is at least one selected from dibutyl phthalate, diisooctyl phthalate, diisononyl phthalate, dioctyl adipate, tricresyl phosphate, triethyl citrate, acetyl tributyl citrate, silicone oil, liquid paraffin, naphthenic oil, aromatic oil, palm oil, soybean oil, rapeseed oil, sunflower oil, corn oil and linseed oil, The content of the heat-expandable microspheres is 305 to 750 parts by weight relative to 100 parts by weight of the matrix resin. The content of the liquid compound is 205 to 1000 parts by weight relative to 100 parts by weight of the matrix resin. The masterbatch for foam molding has a Mooney viscosity ML1+4 at 100° C. of 15 to 90.

2. The masterbatch for foam molding according to claim 1, wherein The ethylene content of the EPDM is 45 wt% to 72 wt%.

3. The foam molding masterbatch according to claim 1 or 2, wherein The diene content of the EPDM is 2.2 wt% to 10.0 wt%.

4. The foam molding masterbatch according to claim 1 or 2, wherein The matrix resin is composed of the EPDM.

5. The foam molding masterbatch according to claim 1 or 2, wherein The content of the heat-expandable microspheres is 325 to 750 parts by weight relative to 100 parts by weight of the matrix resin.

6. The masterbatch for foam molding according to claim 1 or 2, wherein The liquid compound is at least one selected from silicone oil, liquid paraffin, naphthenic oil, aromatic oil, palm oil, soybean oil, rapeseed oil, sunflower oil, corn oil, and linseed oil.

7. A resin composition comprising the masterbatch for foam molding according to claim 1 or 2 and a matrix resin. A foamed molded product, which is a molded product of the resin composition according to claim 7.

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