JP6955853B2 - Foam molding composition, foam molding, and heat-expandable microspheres for foam molding - Google Patents

Description

The present invention relates to a foam molding composition, a foam molding body, and a heat-expandable microsphere for foam molding.

Currently, products made of plastics such as thermoplastic resins are widely used all over the world, and the amount used is increasing year by year. Since thermoplastic resins are made from petroleum, there is a problem that the amount of carbon dioxide generated increases due to the depletion of petroleum and the incineration of waste materials, leading to global warming.
In order to solve the above problem, a filler is added to reduce the amount of the thermoplastic resin used, and further, in order to suppress the increase in mass due to the addition of the filler, it is considered to foam the thermoplastic resin to reduce the weight. It has been done.

Examples of the method for foaming the thermoplastic resin include a method in which the chemical foaming agent is decomposed by the heat generated when the resin is melted and foamed by the gas generated at that time. However, in this method, if the amount of the filler compounded is increased in order to reduce the amount of the thermoplastic resin used, the compounding ratio of the resin that can contain bubbles of the chemical foaming agent becomes small, and the heating during resin molding causes the resin to be compounded. Bubbles of the vaporized foaming agent easily escaped from the resin, and it was difficult to stably retain the bubbles in the molded body.

Further, Patent Document 1 discloses a foam molded product of a thermoplastic elastomer containing an inorganic filler, but when the exemplified heat-expandable microspheres are used, the heat-expandable microspheres are destroyed during the molding process. Therefore, a molded product having a sufficient coefficient of thermal expansion cannot be produced, and a dent is generated at a portion where the thermoplastic microspheres are broken, so that there is a problem that the appearance of the foamed molded product is impaired.

Japanese Unexamined Patent Publication No. 2004-217894

As described above, a foam molding composition containing an inorganic filler, which can suppress the destruction of heat-expandable microspheres and produce a foam molded product having a sufficient coefficient of thermal expansion, is the same. Not until.
An object of the present invention is a composition for foam molding containing an inorganic filler, which can suppress dents on the surface of a molded product due to destruction of heat-expandable microspheres during molding and has a high expansion coefficient for foam molding. It is an object of the present invention to provide a composition, a foam molded product obtained by molding the foam molding composition, and a heat-expandable microsphere that can be suitably used for the foam molding composition.

As a result of diligent studies to solve the above problems, the present inventors have made a foam molding composition containing a base material component excluding a vinyl chloride resin, a heat-expandable microsphere, and a predetermined amount of an inorganic filler. In the above, by using the heat-expandable microspheres in which the internal pressure of the heat-expandable microspheres is within a predetermined range at a specific temperature, a foamed molded product having an excellent appearance can be obtained and the coefficient of thermal expansion is high. We found that and arrived at the present invention.

That is, the composition for foam molding of the present invention is a group excluding heat-expandable microspheres and vinyl chloride-based resin composed of an outer shell made of a thermoplastic resin and a foaming agent contained therein and vaporized by heating. A foam molding composition containing a material component and an inorganic filler, wherein the weight ratio of the inorganic filler to the foam molding composition is 20 to 70% by weight, and the heat-expandable microspheres at 140 ° C. The internal pressure of the heat-expandable microspheres at 250 ° C. is 0.6 to 1.4 MPa, and the internal pressure of the heat-expandable microspheres is 3 to 6.2 MPa.

It is preferable that the composition for foam molding of the present invention further satisfies at least one selected from the following 1) to 5).
1) The weight ratio of the heat-expandable microspheres is 1 to 20 parts by weight with respect to 100 parts by weight of the inorganic filler.
2) The thermoplastic resin is a polymer of a polymerizable component containing a nitrile-based monomer.
3) The polymerizable component further contains a carboxyl group-containing monomer.
4) The expansion start temperature of the thermally expandable microsphere is 140 to 200 ° C.
5) The inorganic filler is magnesium hydroxide, aluminum hydroxide, calcium hydroxide, silica, alumina, titanium oxide, magnesium oxide, calcium oxide, zinc oxide, antimony trioxide, antimony pentoxide, calcium sulfate, barium sulfate, Choose from potassium carbonate, calcium carbonate, magnesium carbonate, aluminum silicate, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, calcium aluminum silicate, talc, mica, wallastnite, glass beads and carbon black At least one species.

The foam-molded product of the present invention is obtained by molding the above-mentioned foam-molding composition.
The ratio of the volume of bubbles to the volume of the inorganic filler (air bubbles: inorganic filler) in the foam molded product is preferably 0.5: 1 to 23: 1.

The heat-expandable microspheres for foam molding of the present invention are used in combination with an inorganic filler, and are composed of an outer shell made of a nitrile-based thermoplastic resin and a foaming agent contained therein and vaporized by heating. The internal pressure of the heat-expandable microspheres at 140 ° C. is 0.6 to 1.4 MPa, and the internal pressure of the heat-expandable microspheres at 250 ° C. is 3 to 6.2 MPa.

The foam molding composition of the present invention can suppress dents on the surface of the molded body due to destruction of heat-expandable microspheres during molding, and can obtain a foam molded product having a high coefficient of thermal expansion.
The foam molded product of the present invention has an excellent appearance and a high foaming ratio.
By using the heat-expandable microspheres for foam molding of the present invention, it is possible to suppress dents on the surface of the molded body due to destruction of the heat-expandable microspheres during molding, and to obtain a foamed molded product having a high coefficient of thermal expansion.

It is the schematic which shows an example of the thermal expansion microsphere for foam molding.

[Composition for foam molding]
The foam molding composition of the present invention contains specific heat-expandable microspheres, a base material component excluding vinyl chloride resin, and an inorganic filler, and the weight ratio of the inorganic filler to the foam molding composition is 20. ~ 70% by weight. This will be described in detail below.

(Inorganic filler)
The inorganic filler is an essential component of the foamed molded article of the present invention. The weight ratio of the inorganic filler to the foam molding composition is 20 to 70% by weight, preferably 30 to 68% by weight, more preferably 40 to 60% by weight, still more preferably 45 to 55% by weight. %. When the weight ratio is less than 20% by weight, it is insufficient in terms of suppressing the amount of resin used, and the rigidity of the obtained foamed molded product is also low. On the other hand, when the weight ratio exceeds 70% by weight, the foamed molded product produced from the foamable molding composition is cracked or torn.

The inorganic filler used in the present invention is magnesium hydroxide, aluminum hydroxide, calcium hydroxide, silica, alumina, titanium oxide, magnesium oxide, calcium oxide, zinc oxide, antimony trioxide, antimony pentoxide, calcium sulfate, barium sulfate. , From potassium carbonate, calcium carbonate, magnesium carbonate, aluminum silicate, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, calcium silicate aluminum, talc, mica, wallastnite, glass beads and carbon black At least one selected.
As the inorganic filler, those whose surface is treated with saturated fatty acid, unsaturated fatty acid, resin acid or the like, salts thereof, silane coupling agent or the like may be used.
The inorganic filler used in the present invention excludes inorganic fibers such as carbon fibers and glass fibers. When an inorganic fiber is used as a filler, the foamed molded product is likely to be distorted, and a preferable foamed molded product may not be obtained.

Among these inorganic fillers, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, silica, alumina, titanium oxide, magnesium oxide, calcium oxide, zinc oxide, trioxide from the viewpoint of economy and moldability of foamed molded product. Antimon, Antimon pentoxide, potassium carbonate, calcium carbonate, magnesium carbonate, talc, mica, wallastnite, glass beads are preferred, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, talc , Mica is more preferred.

The average particle size of the inorganic filler is preferably 1 to 15 μm, more preferably 1.5 to 10 μm. If the average particle size of the inorganic filler is smaller than 1 μm, it may not be sufficiently dispersed in the molded foamed molded product. On the other hand, when the average particle size of the inorganic filler is larger than 15 μm, the strength of the molded foam molded product decreases.

(Thermal expansion microspheres for foam molding)
The heat-expandable microspheres used in the present invention are for foam molding and are used in combination with an inorganic filler. As shown in FIG. 1, the thermally expandable microspheres are thermally expanded composed of an outer shell (shell) 11 made of a thermoplastic resin and a foaming agent (core) 12 contained therein and vaporized by heating. It is a sex microsphere. The heat-expandable microspheres have a core-shell structure, and the heat-expandable microspheres exhibit thermal expansion (the property that the entire microspheres swell by heating) as a whole.

From the viewpoint of further exerting the effect of the present invention, the weight ratio of the heat-expandable microspheres is preferably 1 to 20 parts by weight, more preferably 2 to 18 parts by weight, based on 100 parts by weight of the inorganic filler. It is more preferably 3 to 15 parts by weight, and particularly preferably 4 to 13 parts by weight. When the weight ratio is less than 1 part by weight, the amount of the heat-expandable microspheres added is small, so that the weight reduction of the foamed molded product may be insufficient. On the other hand, when the weight ratio exceeds 20 parts by weight, the strength of the molded foamed molded product may decrease.

The weight ratio of the heat-expandable microspheres to the composition for foam molding is preferably 0.5 to 12% by weight, more preferably 0.7 to 10% by weight, still more preferably 1.5 to 7%. It is% by weight, particularly preferably 2 to 5% by weight. If the weight ratio is less than 0.5% by weight, the weight reduction of the obtained foamed molded product may be insufficient. On the other hand, when the weight ratio exceeds 12% by weight, the strength of the molded foamed molded product may be low.

The foaming agent is a component that evaporates when heated, and by being encapsulated in the outer shell made of the thermoplastic resin of the heat-expandable microspheres, the heat-expandable microspheres are thermally expandable (microspheres as a whole). The whole body swells when heated).
In order to exert the effect of the present application, the internal pressure of the heat-expandable microspheres at 140 ° C. needs to be 0.6 to 1.4 MPa, and the internal pressure of the heat-expandable microspheres at 250 ° C. needs to be 3 to 6.2 MPa. be. By using the heat-expandable microspheres having such a specific internal pressure, even when a predetermined amount of the inorganic filler is blended, the heat-expandable microspheres do not expand significantly during molding, so that heat is generated. The outer shell of the inflatable microspheres does not become thin, and the destruction of the heat-expandable microspheres can be suppressed. As a result, it is possible to suppress dents on the surface of the molded product due to the destruction of the heat-expandable microspheres during molding, and to obtain a foamed molded product having a high coefficient of thermal expansion.

From the viewpoint of further exerting the effects of the present invention, the internal pressure of the heat-expandable microspheres at 140 ° C. is preferably 0.7 to 1.3 MPa, more preferably 0.8 to 1.2 MPa, still more preferably 0.9. It is ~ 1.1 MPa. When the internal pressure is less than 0.6 MPa, the expansion coefficient of the thermally expandable microspheres may be low, and the expansion coefficient of the obtained foamed molded product may be low. On the other hand, when the internal pressure exceeds 1.4 MPa, the heat-expandable microspheres expand significantly during molding, the outer shell of the heat-expandable microspheres becomes thin, and is destroyed by contact with the inorganic filler. The desired lightweight foam molding may not be obtained.
Similarly, from the viewpoint of further exerting the effect of the present invention, the internal pressure of the heat-expandable microspheres at 250 ° C. is preferably 3.1 to 6 MPa, more preferably 3.6 to 5.5 MPa, still more preferably 4 to 4. It is 5.2 MPa, particularly preferably 4.2 to 5 MPa. When the internal pressure is less than 3 MPa, the expansion coefficient of the thermally expandable microspheres may be low, and the expansion coefficient of the obtained foamed molded product may be low. On the other hand, when the internal pressure exceeds 6.2 MPa, the heat-expandable microspheres expand significantly during molding, the outer shell of the heat-expandable microspheres becomes thin, and is destroyed by contact with the inorganic filler. The desired lightweight foam molding may not be obtained.

Here, the internal pressure of the heat-expandable microspheres at 140 ° C. (or 250 ° C.) in the present invention means the vapor pressure of the entire foaming agent at that temperature. When the foaming agent is composed of a plurality of components, the internal pressure of the heat-expandable microspheres at 140 ° C. (or 250 ° C.) is the vapor pressure of each component at 140 ° C. (or 250 ° C.). The value calculated by multiplying the mole fractions of and summing the multiplied values.

The foaming agent is not particularly limited as long as the above internal pressure is satisfied, but for example, propane, butane, pentane, hexane, heptane, octane, nonane, decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane and the like. Linear hydrocarbons of Branched hydrocarbons such as 4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, 2,6,10,14-tetramethylpentadecane; cyclododecane, cyclotridecane, hexylcyclohexane, heptylcyclohexane, Hydrocarbons such as n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane; petroleum ethers; their halides; fluorine-containing compounds such as hydrofluoroether; Tetraalkylsilane; examples thereof include compounds that generate gas by thermal decomposition by heating. The foaming agent may be linear, branched or alicyclic, and is preferably an aliphatic one. These foaming agents may be used alone or in combination of two or more as long as the above internal pressure is satisfied.

The foaming agent may contain a hydrocarbon having 13 or more carbon atoms from the viewpoint of adjusting the heat resistance and the internal pressure of the heat-expandable microspheres. The weight ratio of the hydrocarbon having 13 or more carbon atoms to the foaming agent is preferably 0 to 40% by weight, more preferably 5 to 33% by weight, and further preferably 10 to 25% by weight.
The foaming agent preferably contains a hydrocarbon having 11 or less carbon atoms from the viewpoint of increasing the expansion coefficient of the thermally expandable microspheres. The weight ratio of the hydrocarbon having 11 or less carbon atoms to the foaming agent is preferably 50 to 100% by weight, more preferably 55 to 90% by weight, and further preferably 60 to 85% by weight. Further, the total weight ratio of the hydrocarbon having 13 or more carbon atoms and the hydrocarbon having 11 or less carbon atoms in the foaming agent is preferably more than 70% by weight, more preferably more than 73% by weight, still more preferably more than 80% by weight. Is.
Further, from the viewpoint of adjusting the internal pressure of the heat-expandable microspheres, a hydrocarbon having 12 carbon atoms in the foaming agent may be contained. The weight ratio of the hydrocarbon having 12 carbon atoms to the foaming agent is preferably less than 30% by weight, more preferably less than 27% by weight, still more preferably less than 20% by weight.

The coefficient of encapsulation of the foaming agent is defined as a percentage of the weight of the foaming agent contained in the heat-expandable microspheres with respect to the weight of the heat-expandable microspheres. The inclusion ratio of the foaming agent is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 45% by weight, still more preferably 5 to 40% by weight, based on the weight of the heat-expandable microspheres. Particularly preferably, it is 10 to 30% by weight.

The thermoplastic resin that forms the outer shell of the heat-expandable microspheres is a polymer of a polymerizable component (obtained by polymerizing the polymerizable component). The polymerizable component is a component that requires a monomer component and may contain a cross-linking agent. The monomer component means a radically polymerizable monomer having one polymerizable double bond, and is a component capable of addition polymerization. Further, the cross-linking agent means a radically polymerizable monomer having a plurality of polymerizable double bonds, and is a component for introducing a bridging structure into a thermoplastic resin.

The polymerizable component preferably contains a nitrile-based monomer from the viewpoint of gas barrier properties of the heat-expandable microspheres. Examples of the nitrile-based monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, and the like.
The nitrile-based monomer preferably contains acrylonitrile and / or methacrylonitrile from the viewpoint of increasing the strength of the outer shell of the heat-expandable microspheres, and preferably contains methacrylonitrile indispensably.
The weight ratio of methacrylonitrile to the nitrile-based monomer is preferably 25 to 50% by weight, more preferably 30 to 45% by weight, and even more preferably 32 to 40% by weight.

The weight ratio of the nitrile-based monomer to the polymerizable component is not particularly limited, but is preferably 55% by weight or more, more preferably 60 to 99.5% by weight, still more preferably 80 to 99% by weight, and particularly preferably. Is 90-98% by weight. When the weight ratio is less than 55% by weight, the strength of the outer shell of the heat-expandable microspheres decreases, the heat-expandable microspheres are destroyed during molding, and a desired lightweight foam molded product cannot be obtained. There is.

The polymerizable component may further contain a carboxyl group-containing monomer from the viewpoint that a foamed molded product can be produced using a base material component having a high melting temperature or softening temperature.
The carboxyl group-containing monomer is not particularly limited as long as it has one or more free carboxyl groups per molecule, but is an unsaturated product such as acrylic acid, methacrylic acid, etacrylic acid, crotonic acid, and silicic acid. Carboxyl acid; unsaturated dicarboxylic acid such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid; anhydride of unsaturated dicarboxylic acid; monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, fumal Examples thereof include unsaturated dicarboxylic acid monoesters such as monoethyl acid, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate. These carboxyl group-containing monomers may be used alone or in combination of two or more. In the carboxyl group-containing monomer, a part or all of the carboxyl groups may be neutralized at the time of polymerization or after polymerization.

When the carboxyl group-containing monomer is contained in the polymerizable component, the weight ratio of the carboxyl group-containing monomer to the polymerizable component is not particularly limited, but is preferably 13 to 61% by weight, more preferably 20 to 60. By weight%, more preferably 25-55% by weight, particularly preferably 30-50% by weight.

When the polymerizable component contains a carboxyl group-containing monomer, the polymerization ratio of the nitrile group-containing monomer in the polymerizable component is not particularly limited, but is preferably 35 to 87% by weight, more preferably 38 to 80%. By weight%, more preferably 40 to 70 parts by weight, particularly preferably 42 to 60 parts by weight.

The polymerizable component may further contain a (meth) acrylic acid ester-based monomer from the viewpoint of facilitating control of expansion behavior. In addition, (meth) acrylic means acrylic or methacryl.
The (meth) acrylic acid ester-based monomer is not particularly limited, but is limited to methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth). ) Acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate and the like. ..

The weight ratio of the (meth) acrylic acid ester-based monomer to the polymerizable component is not particularly limited, but is preferably less than 45% by weight, more preferably 0.1 to 36% by weight, still more preferably 0.5. ~ 20% by weight, particularly preferably 0.8-10% by weight. When the weight ratio is 45% by weight or more, the strength of the outer shell of the heat-expandable microspheres decreases, the heat-expandable microspheres are destroyed during molding, and a desired lightweight foam molded product cannot be obtained. There is.

The polymerizable component may contain a monomer other than the above-mentioned nitrile-based monomer, carboxyl group-containing monomer, and (meth) acrylic acid ester-based monomer, as long as the effect of the present invention is not impaired. good. Examples of the monomer include a halogen-containing monomer, a (meth) acrylic acid amide-based monomer, a styrene-based monomer, and a monomer that reacts with a carboxyl group of a carboxyl group-containing monomer. .. Furthermore, vinyl ester-based monomers such as vinyl acetate, vinyl propionate, vinyl butyrate; maleimide-based monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; ethylene unsaturated monoolefines such as ethylene, propylene and isobutylene. Monomer; Vinyl ether monomer such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Vinyl ketone monomer such as vinyl methyl ketone; N-vinyl monomer such as N-vinylcarbazole, N-vinylpyrrolidone, etc. Monomer; vinyl naphthaline salt and the like can be mentioned.

The halogen-containing monomer is not particularly limited, and examples thereof include vinyl chloride and vinylidene chloride.
The (meth) acrylic acid amide-based monomer is not particularly limited, and examples thereof include acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide.
The styrene-based monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, p-nitrostyrene, and chloromethylstyrene.

The monomer that reacts with the carboxyl group of the carboxyl group-containing monomer is not particularly limited, but is limited to N-methylol (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylamino. Propyl (meth) acrylate, vinyl glycidyl ether, propenyl glycidyl ether, glycidyl (meth) acrylate, glycerin mono (meth) acrylate, 4-hydroxybutyl acrylate glycidyl ether, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, p-hydroxystyrene and the like can be mentioned.

As described above, the polymerizable component may contain a cross-linking agent. By polymerizing with a cross-linking agent, the obtained thermally expandable microspheres can be effectively thermally expanded by suppressing a decrease in the retention rate (encapsulation retention rate) of the encapsulated foaming agent during thermal expansion. can.
The cross-linking agent is not particularly limited, but for example, an aromatic divinyl compound such as divinylbenzene; allyl methacrylate, triacrylic formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tri. Ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polytetramethylene glycol diacrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1, 9-Nonandiol di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, trimethylpropantri (meth) acrylate, pentaerythritol Tri (meth) acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, tricyclodecanedimethanol di (meth) acrylate, etc. Examples thereof include polyfunctional (meth) acrylate compounds. These cross-linking agents may be used alone or in combination of two or more.

The cross-linking agent may be omitted, but the amount thereof is not particularly limited, and is preferably 0 to 3.0 parts by weight, more preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of the monomer component. It is by weight, particularly preferably 0.02 to 1.0 parts by weight. If the amount of the cross-linking agent is more than 3.0 parts by weight, the expandability of the heat-expandable microspheres may decrease, and the expansion ratio of the foamed molded product may decrease.

The maximum expansion coefficient of the thermally expandable microsphere is not particularly limited, but is preferably 3 times or more, more preferably 10 times or more, still more preferably 20 times or more, particularly preferably 30 times or more, still more preferably 50 times or more. Most preferably, it is 70 times or more. On the other hand, the upper limit of the maximum expansion ratio is preferably 200 times.

The expansion start temperature (Ts) of the thermally expandable microspheres is preferably 140 to 200 ° C., more preferably 144 to 199 ° C., further preferably 150 to 195 ° C., particularly preferably 160 to 190 ° C., and most preferably 170 to 170 ° C. It is 185 ° C. If the expansion start temperature of the heat-expandable microspheres is less than 140 ° C., the heat-expandable microspheres expand during molding, the outer shell of the heat-expandable microspheres becomes thin, and is destroyed by contact with an inorganic filler. In some cases, the desired lightweight foam molded product cannot be obtained. On the other hand, when the expansion start temperature of the heat-expandable microspheres exceeds 200 ° C., the heat resistance of the heat-expandable microspheres becomes high, and the heat-expandable microspheres do not expand sufficiently during molding. Insufficient weight reduction may occur.

The maximum expansion temperature (Tmax) of the thermally expandable microspheres is preferably 175 to 275 ° C, more preferably 180 to 260 ° C, still more preferably 185 to 250 ° C, and particularly preferably 190 to 240 ° C. If the maximum expansion temperature of the heat-expandable microspheres is less than 175 ° C., sufficient heat resistance cannot be obtained, and the foaming agent contained in the heat-expandable microspheres at the time of molding becomes the outer shell of the heat-expandable microspheres. It may escape from the thermoplastic resin to the outside, and the desired lightweight foamed molded product may not be obtained. On the other hand, when the maximum expansion temperature of the heat-expandable microspheres exceeds 275 ° C., the heat resistance of the heat-expandable microspheres becomes high, and the heat-expandable microspheres do not expand sufficiently during molding. Insufficient weight reduction may occur.

The average particle size of the heat-expandable microspheres is not particularly limited, but is preferably 0.5 to 200 μm, more preferably 1 to 100 μm, still more preferably 3 to 80 μm, particularly preferably 7 to 60 μm, and most preferably 10 to 10. It is 50 μm. If the average particle size is smaller than 0.5 μm, the expansion performance of the thermally expandable microspheres may be low. On the other hand, when the average particle size is larger than 200 μm, the strength of the heat-expandable microspheres decreases, and the heat-expandable microspheres may be destroyed during molding.

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 45% or less, and particularly preferably 40% or less. The coefficient of variation CV is calculated by the following formulas (1) and (2).

（式中、ｓは粒子径の標準偏差、＜ｘ＞は平均粒子径、ｘ_ｉはｉ番目の粒子径、ｎは粒子の数である。）

(Wherein, s is the standard deviation of the particle size, <x> is an average particle size, x _i is the i-th particle diameter, n is the number of particles.)

The method for producing thermally expandable microspheres is a step of dispersing an oily mixture containing a polymerizable component, a foaming agent, and a polymerization initiator in an aqueous dispersion medium and polymerizing the polymerizable component (hereinafter, polymerization). It is a manufacturing method including a process).

The polymerization initiator is not particularly limited, and examples thereof include peroxides and azo compounds that are very commonly used.
Examples of the peroxide include peroxydicarbonates such as diisopropyl peroxy dicarbonate, di-sec-butyl peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, and dibenzyl peroxy dicarbonate; lauroyl peroxide. Diacyl peroxides such as benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 2,2-bis (t-butylperoxy) butane; cumenehydroperkiside, t-butyl Hydroperoxides such as hydroperoxides; dialkyl peroxides such as dicumyl peroxides and di-t-butyl peroxides; peroxyesters such as t-hexylperoxypivalate and t-butylperoxyisobutyrate. be able to.

Examples of the azo compound include 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 2,2'-azobis (2,4-). Dimethylvaleronitrile), 2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), etc. Can be mentioned.

The weight ratio of the polymerization initiator is preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight, and most preferably 0.2 to 5% by weight with respect to 100 parts by weight of the polymerizable component. % By weight. If the weight ratio is less than 0.05% by weight, the non-polymerizable polymerizable component remains, and the fluidity of the heat-expandable microspheres may deteriorate. If the weight ratio exceeds 10% by weight, the heat resistance is lowered.

In the method for producing thermally expandable microspheres, an aqueous suspension in which an oily mixture is dispersed in an aqueous dispersion medium is prepared, and a polymerizable component is polymerized.
The aqueous dispersion medium is a medium containing water as a main component, such as ion-exchanged water for dispersing an oily mixture, and may further contain alcohols such as methanol, ethanol and propanol, and hydrophilic organic solvents such as acetone. good. Hydrophilicity in the present invention means that it is in a state of being arbitrarily miscible with water. The amount of the aqueous dispersion medium used is not particularly limited, but it is preferable to use 100 to 1000 parts by weight of the aqueous dispersion medium with respect to 100 parts by weight of the polymerizable component.

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, sodium carbonate and the like. These electrolytes may be used alone or in combination of two or more. The content of the electrolyte is not particularly limited, but is preferably 0.1 to 50 parts by weight with respect to 100 parts by weight of the aqueous dispersion medium.

The aqueous dispersion medium is a water-soluble 1,1-substituted compound having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group and a phosphonic acid (salt) group and a hetero atom are bonded to the same carbon atom. Classes, potassium dichromate, alkali metal nitrite, metal (III) halide, boric acid, water-soluble ascorbic acid, water-soluble polyphenols, water-soluble vitamin B and water-soluble phosphonic acid (salt). It may contain at least one water-soluble compound. The water solubility in the present invention means that 1 g or more is dissolved per 100 g of water.

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 parts by weight, more preferably 0.0003 to 100 parts by weight, based on 100 parts by weight of the polymerizable component. It is 0.1 parts by weight, particularly preferably 0.001 to 0.05 parts by weight. If the amount of the water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. Further, if the amount of the water-soluble compound is too large, the polymerization rate may decrease or the residual amount of the polymerizable component as a raw material may increase.

The aqueous dispersion medium may contain a dispersion stabilizer or a dispersion stabilization aid in addition to the electrolyte and the water-soluble compound.
The dispersion stabilizer is not particularly limited, and examples thereof include tricalcium phosphate, magnesium pyrophosphate and calcium pyrophosphate obtained by the metathesis formation method, colloidal silica, alumina sol, magnesium hydroxide and the like. These dispersion stabilizers may be used alone or in combination of two or more.
The blending amount of the dispersion stabilizer 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.
The dispersion stabilizing aid is not particularly limited, but for example, an interface such as a polymer type dispersion stabilizing aid, a cationic surfactant, an anionic surfactant, an amphoteric ion surfactant, or a nonionic surfactant. Activators can be mentioned. These dispersion stabilizing aids may be used alone or in combination of two or more.

The aqueous dispersion medium is prepared, for example, by blending water (ion-exchanged water) with a water-soluble compound, and if necessary, a dispersion stabilizer and / or a dispersion stabilization aid. The pH of the aqueous dispersion medium at the time of polymerization is appropriately determined depending on the types of the water-soluble compound, the dispersion stabilizer, and the dispersion stabilization aid.

In the method for producing thermally expandable microspheres, polymerization may be carried out in the presence of sodium hydroxide, sodium hydroxide and zinc chloride.
In the production method of the present invention, the oily mixture is suspended and dispersed in an aqueous dispersion medium so that spherical oil droplets having a predetermined particle size are prepared.

Examples of the method of suspending and dispersing the oily mixture include a method of stirring with a homomixer (for example, manufactured by Tokushu Kagaku Kogyo Co., Ltd.) and a static dispersion of a static mixer (for example, manufactured by Noritake Engineering Co., Ltd.). General dispersion methods such as a method using an apparatus, a membrane suspension method, and an ultrasonic dispersion method can be mentioned.
Then, suspension polymerization is started by heating the dispersion liquid in which the oily mixture is dispersed as spherical oil droplets in an aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the dispersion liquid, and the stirring may be performed slowly so as to prevent, for example, the floating of the monomer and the sedimentation of the heat-expandable microspheres after the polymerization.

The polymerization temperature is freely set depending on the type of the polymerization initiator, but is preferably controlled in the range of 30 to 100 ° C., more preferably 40 to 90 ° C. The time for maintaining the reaction temperature is preferably about 1 to 20 hours. The initial polymerization pressure is not particularly limited, but the gauge pressure is in the range of 0 to 5 MPa, more preferably 0.1 to 3 MPa.

In the method for producing thermally expandable microspheres, a metal salt may be added to the polymerized slurry (thermally expandable microsphere-containing dispersion) to form an ionic crosslink with a carboxyl group, which is an organic compound containing a metal. The surface may be treated.
The metal salt is preferably a divalent or higher valent metal cation, and examples thereof include Al, Ca, Mg, Fe, Ti, and Cu. Water-soluble is preferable from the viewpoint of ease of addition, but water-insoluble may be used. The metal-containing organic compound is preferably water-soluble from the viewpoint of surface treatment efficiency, and an organic compound containing a metal belonging to Periodic Tables 3 to 12 is preferable because the heat resistance is further improved.

The obtained slurry is filtered by a centrifuge, a pressure press, a vacuum dehydrator or the like, and a cake-like product having a water content of 10 to 50% by weight, preferably 15 to 45% by weight, more preferably 20 to 40% by weight. The cake-like material is dried by a shelf-type dryer, an indirect heating dryer, a fluidized dryer, a vacuum dryer, a vibration dryer, an air flow dryer, etc., and has a water content of 6% by weight or less, preferably 5% by weight or less. Is.
For the purpose of reducing the content of ionic substances, the cake-like substance may be washed with water and / or redispersed, then refiltered and dried. Further, the slurry may be dried by a spray dryer, a fluidized dryer or the like to obtain a dry powder.

(Base material component)
The base material component is a component that constitutes a foamed molded product, and is a component that enables a certain shape to be imparted by molding. The base material component used in the present invention excludes vinyl chloride resin. Here, the vinyl chloride-based resin is a resin obtained by polymerizing only the vinyl chloride monomer as a polymerizable component, and the vinyl chloride monomer as the main component (the weight ratio of the vinyl chloride monomer to the polymerizable component is 50 weight by weight). % Or more and less than 100% by weight) means a resin obtained by polymerizing a polymerizable component containing a polymerizable monomer other than a vinyl chloride monomer such as a vinyl chloride monomer.

The base material component is not particularly limited, but for example, natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber, etc. Rubbers such as silicon rubber, acrylic rubber, urethane rubber, fluororubber, ethylene-propylene-diene rubber (EPDM); thermoplastic resins such as epoxy resin, phenol resin, unsaturated polyester resin, polyurethane; polyethylene wax, paraffin wax, etc. Waxes; ethylene-vinyl acetate copolymer (EVA), polyethylene, modified polyethylene, polypropylene, modified polypropylene, modified polyolefin, acrylic resin, thermoplastic polyurethane, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene- Thermoplastic resins such as styrene copolymer (ABS resin), polystyrene (PS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyacetal (POM); ethylene-based ionomer, urethane-based ionomer, styrene-based ionomer, etc. Ionomer resin; thermoplastic elastomers such as olefin-based elastomers, styrene-based elastomers, and polyester-based elastomers; bioplastics such as polylactic acid (PLA), PBS, PHA, and starch resins; modified silicon-based, urethane-based, polysulfide-based, acrylic-based, Sealing materials such as silicon-based, thermoplastic-based, and butyl rubber-based; urethane-based, ethylene-vinyl acetate copolymer-based, vinyl chloride-based, acrylic-based coating components and the like can be mentioned.
Among these, rubbers, waxes, thermoplastic resins, ionomer resins, thermoplastic elastomers, and bioplastics are preferable from the viewpoint of moldability of the foamed molded product containing the inorganic filler.

The melting point or softening point of the base material component is preferably 50 to 250 ° C., more preferably 100 to 200 ° C. from the viewpoint of moldability of the foam molded product containing the inorganic filler. When the melting point or softening point of the base material component is lower than 50 ° C., the produced foamed molded products are likely to adhere to each other. If the melting point or softening point of the base material component is higher than 250 ° C., it may be difficult to prepare a foam molded product containing an inorganic filler.

The weight ratio of the base material component to the composition for foam molding is preferably 25 to 78% by weight, more preferably 35 to 70% by weight, still more preferably 40 to 60% by weight, and particularly preferably 40 to 60% by weight. It is 45 to 55% by weight. If the weight ratio is less than 25% by weight, cracks or tears may occur in the obtained foamed molded product. On the other hand, when the weight ratio exceeds 78% by weight, it is insufficient in terms of suppressing the amount of resin used, and the rigidity of the obtained foamed molded product may be lowered.

(Other ingredients)
In addition to the heat-expandable microspheres and base material components, various additives such as organic fillers, plasticizers, lubricants, antioxidants, colorants, antistatic agents, and stabilizers are contained as required. You may. In that case, various additives may be added as a third component to the heat-expandable microspheres and the base material component.

Examples of the organic filler include cellulosic fibers such as cotton fiber, hemp fiber and kenaf fiber, cellulosic powder such as paper flour, wood flour, bamboo flour, rice husk flour and fruit husk flour, and starch.

The plasticizer is not particularly limited, but is diisononyl flalate (DINP), dioctylphthalate (DOP), dibutylphthalate (DBP), butyloctylphthalate (BOP), diisononyl adipate (DINA), trioctyl trimetate (TOTM). , Tricresyl phosphate (TCP), tributyl acetylcitrate (ATBC), epoxidized soybean oil, epoxidized flaxseed oil and the like.

The stabilizer is not particularly limited, but is a phenol-based stabilizer, a sulfur-based stabilizer, a phosphorus-based stabilizer, an organic tin-based stabilizer, a lead-based stabilizer, a calcium-zinc-based stabilizer, and a calcium-zinc-based stabilizer. Antioxidants such as; UV absorbers, light stabilizers such as hindered amine stabilizers; hydrotalcites; and the like.

The lubricant is not particularly limited, but is a metal soap such as calcium stearate, magnesium stearate, barium stearate, lead stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, calcium ricinolate; paraffin wax. , Hydrocarbon waxes such as liquid paraffin; amide waxes such as stearic acid amide, oleic acid amide, erucic acid amide, methylene bisstearic acid amide, ethylene bisstearic acid amide; stearic acid monoglyceride, stearyl stearate, butyl stearate. Etc.; ester-based waxes such as; fatty acid-based waxes such as stearic acid; higher alcohol-based waxes such as stearyl alcohol; and the like.
Examples of the colorant include carbon black, titanium oxide, kaolin, chromium yellow, phthalocyanine blue, and chrome yellow.
The antistatic agent is not particularly limited, and examples thereof include an anionic antistatic agent and a nonionic antistatic agent.

(Manufacturing method of composition for foam molding)
The method for producing the composition for foam molding is as follows: 1) The above-mentioned inorganic filler, heat-expandable microspheres and base material component are equal to or higher than the melting point or softening point of the base material component and lower than the expansion start temperature of the heat-expandable microspheres. A method for producing a compound (composition for foam molding) of an inorganic filler, a heat-expandable microsphere and a base material component by melting and kneading at a temperature, and 2) melting or softening the base material component of the inorganic filler and the base material component. A master batch of inorganic filler is produced by melt-kneading at a temperature above the point, and separately, the heat-expandable microspheres and the base material component are added to the heat-expandable microspheres above the melting point or softening point of the base material component. In a method of melt-kneading at a temperature equal to or lower than the expansion start temperature to produce a master batch of thermally expandable microspheres, and uniformly mixing and producing a master batch of an inorganic filler and thermally expandable microspheres, 3) 1). , A method for producing a compound (composition for foam molding) by changing the inorganic filler to the master batch of the inorganic filler described in 2), and in 4) 1), the thermally expandable microspheres are described in 2). Examples thereof include a method of producing a compound (composition for foam molding) instead of a master batch of thermally expandable microspheres.
The method for producing the compound or masterbatch is not particularly limited, but it is preferable to mix by a kneader, a roll, a mixing roll, a mixer, a single-screw extruder, a twin-screw extruder, a multi-screw extruder or the like.

As a method for producing the above compound, an inorganic filler, a thermoplastic microsphere, a base material component and other necessary components are mixed in advance with a ribbon mixer, and a Banbury mixer is used to heat the base material component above the melting point or softening point. Examples thereof include a method of melt-kneading at a temperature equal to or lower than the expansion start temperature of the expandable microspheres to prepare a compound of an inorganic filler, a thermally expandable microspheres and a base material component.
A foam molded product can be produced by supplying the produced compound to a single-screw extruder, a twin-screw extruder, or the like and heat-molding the compound. In addition, the manufactured compound is granulated using a kneader, a single-screw extruder, a twin-screw extruder, etc., supplied to a single-screw extruder, a twin-screw extruder, an injection molding machine, etc., and foamed by heat molding. It is possible to manufacture a molded product.

An example of how to make a masterbatch of inorganic fillers is to mix the inorganic fillers, substrate components and other necessary components in advance with a ribbon mixer and then use biaxial extrusion with a die. At a temperature above the melting point or softening point of the base material, the inorganic filler and other necessary components are melt-kneaded, extruded into an appropriate shape with a die, and the obtained kneaded product is air-cooled to a more appropriate shape to be inorganic. Create a masterbatch of filler. Further, the masterbatch of the heat-expandable microspheres is also melt-kneaded at a temperature equal to or higher than the melting point or softening point of the base material component and lower than the expansion start temperature of the heat-expandable microspheres, as in the method for producing the masterbatch of the inorganic filler. Then, it is extruded into an appropriate shape, and the obtained kneaded product is air-cooled and then processed into an appropriate shape to prepare a masterbatch of heat-expandable microspheres. The prepared masterbatch of the inorganic filler and the heat-expandable microspheres and, if necessary, the base material components are added and uniformly mixed with a ribbon mixer.
A foam molded product is formed by supplying a foam molding composition, which is a mixture of the produced inorganic filler and a masterbatch of heat-expandable microspheres, to a single-screw extruder, a twin-screw extruder, an injection molding machine, or the like and heat-molding the mixture. It is possible to manufacture.

The weight ratio of the inorganic filler in the master batch of the inorganic filler is preferably 25 to 80% by weight, more preferably 50 to 75% by weight.
The weight ratio of the heat-expandable microspheres in the masterbatch of the heat-expandable microspheres is preferably 25 to 75% by weight, more preferably 40 to 70% by weight.

[Effervescent molded product and its manufacturing method]
The foam molded product of the present invention is obtained by molding the above-mentioned foam molding composition. Since the foam molded product of the present invention uses the composition for foam molding of the present invention, it can suppress dents on the surface of the molded product due to the destruction of heat-expandable microspheres during molding, and thus has an excellent appearance. It also has a high foaming ratio.

The method for producing a foam molded product includes a step of heat-molding the above-mentioned foam molding composition at a temperature close to the maximum expansion temperature of the thermally expanded microspheres contained in the foam molding composition. The method for thermoforming is not particularly limited, and includes injection molding, extrusion molding such as irregular molding, calendar molding, inflation molding, hollow molding, kneading molding, compression molding, vacuum molding, thermoforming, and the like.
A method for producing a foam molded product will be described by taking as an example a step of producing a foam molded product by extrusion molding. The extrusion molding machine to be used is equipped with a heater and a thermocouple in the cylinder portion, and is equipped with a raw material supply port for supplying the composition for foam molding. Inside the cylinder, a screw is installed to move the foam molding composition from the raw material supply port in the extrusion direction while further melting and kneading.

The foam molding composition supplied into the cylinder has a temperature close to the maximum expansion temperature of the thermally expanded microspheres contained in the rotating cylinder of the screw at or above the melting point or softening point of the base material component (molding of the foam molded product). When heated to (temperature), it becomes a melt-kneaded product, can be molded into a desired shape, and is extruded through a die equipped with a heater and a thermocouple to obtain a foam molded product.
Here, the molding temperature of the foam molded product means the temperature of the melt-kneaded product when the melt-kneaded product moves in the cylinder of the molding machine.

The molding temperature of the foamed molded product is preferably 160 to 250 ° C., more preferably 170 to 240 ° C., still more preferably 180 to 230 ° C. from the viewpoint of the foaming ratio of the foamed molded product. If the temperature is less than 160 ° C., the expansion of the thermally expandable microspheres becomes insufficient, and the target expansion coefficient may not be obtained. On the other hand, when the temperature exceeds 250 ° C., the vaporized foaming agent escapes from the outer shell of the heat-expandable microspheres to the outside, causing a phenomenon of “settling” in which the heat-expandable microspheres contract, and the target expansion coefficient is set. It may not be obtained.

Further, when the extrusion molding machine is provided with a vent in the manufacturing process of the foam molded product, it is desirable to perform molding with the vent closed. When the vent is open, the melt-kneaded product is extruded from the vent, and it may be difficult to obtain a lightweight foamed molded product.
Further, in extrusion molding, it is also possible to connect a vacuum pump or the like to a vent provided immediately before the die and discard it to remove voids generated during kneading.

In the process of manufacturing a foam molded product, the time from when the foam molding composition is charged into the raw material supply port until it is extruded from the die can be adjusted by the number of rotations of the screw. The number of rotations of the screw may be appropriately set depending on the equipment, the type of base material component, etc., but the time (residence time) from when the foam molding composition is put into the raw material supply port until it is extruded from the die is 0. It is preferably 2 to 30 minutes, more preferably 0.3 to 20 minutes, still more preferably 0.5 to 15 minutes, and particularly preferably 0.7 to 5 minutes. If the residence time is less than 0.2 minutes, heating may be insufficient and the expandable microspheres may not expand sufficiently, and a foamed molded product having a desired expansion ratio may not be obtained. On the other hand, if the residence time is longer than 30 minutes, the work efficiency may decrease and a problem may occur in productivity.
The foamed molded product extruded from the die is usually cooled by cooling equipment such as air cooling, water cooling, and a roll to obtain a desired foamed molded product. In the present invention, general equipment such as cooling equipment and take-back equipment can be used.

In the foam molded product of the present invention, the proportion of uniformly independent bubbles (closed cell ratio) is not particularly limited, but is preferably 50% or more, more preferably 60% or more, particularly preferably 65% or more, and most preferably. Is 80% or more. The upper limit of the closed cell ratio is 100%. If the closed cell ratio is less than 50%, the number of communicating bubbles increases, the strength of the obtained foamed molded product becomes weak, and there is also a problem of water absorption, which is not preferable. On the other hand, a foam molded product having a high closed cell ratio is preferable because it has excellent strength and excellent heat insulating properties. The method for evaluating the closed cell ratio will be described in Examples.

The surface dents of the foam molded product of the present invention are preferably 15 or less, more preferably less than 5. If the number of dents on the surface is more than 15 places, the appearance of the obtained foamed molded product may be poor and the strength may be weakened, which is not preferable. When the number of recesses on the surface of the foamed molded product is less than 5, the appearance of the obtained foamed molded product is good and the strength is also excellent, which is preferable. The method for evaluating the surface state will be described in Examples.

The foaming ratio of the foamed molded product of the present invention is preferably 1.2 to 3 times, more preferably 1.3 to 2.7 times. If the foaming ratio is more than 3 times, the strength of the obtained foamed molded product may be low. The method for evaluating the foaming ratio will be described in Examples.

In the foamed molded product of the present invention, the diameter of the bubbles formed inside the foamed molded product by the heat-expanded microspheres is preferably 30 to 400 μm, more preferably 50 to 300 μm, and further preferably 70 to 250 μm. When the bubble diameter of the foamed molded product is smaller than 30 μm, the foaming ratio of the obtained foamed molded product may be low. On the other hand, when the bubble diameter of the foamed molded product is larger than 400 μm, the strength of the obtained foamed molded product may be low. The method for evaluating the bubble diameter will be described in Examples.

The ratio of the volume of bubbles to the volume of the inorganic filler (bubbles: inorganic filler) in the foam molded body is preferably 0.5: 1 to 23: 1, more preferably 0.7: 1 to 20: 1, and further. It is preferably 1.4: 1 to 15: 1. If the ratio is less than 0.5: 1, the foaming ratio of the obtained foamed molded product may be low. On the other hand, if the ratio is larger than 23: 1, the blending amount of the inorganic filler becomes low, which is insufficient in terms of suppressing the amount of resin used, and the rigidity of the obtained foam molded product may also be low. A method for evaluating the ratio of the volume of air bubbles to the volume of the inorganic filler in the foamed molded product will be described in Examples.

Since the foam molded product of the present invention is lightweight, has heat insulating properties, and has excellent rigidity, for example, building materials such as flooring materials, wall materials, embedded panel materials, interior / exterior materials such as automobile bumpers and instrument panels, etc. It is particularly suitable for applications such as electric appliance parts and food containers compatible with microwave ovens.

Hereinafter, examples of the method for producing a foamed molded article of the present invention will be specifically described. The present invention is not limited to these examples. In the following examples and comparative examples, "%" means "% by weight" unless otherwise specified.
In addition, the physical properties of the heat-expandable microspheres used below and the foamed molded products molded in Examples and Comparative Examples were evaluated as follows. The heat-expandable microsphere may be simply referred to as a microsphere, and the foam molded product may be simply referred to as a molded product.
Further, Examples 1-12, 1-13, 2-12 and 2-13 are used as reference examples, respectively.

[Measurement of average particle size and particle size distribution]
A laser diffraction type particle size distribution measuring device (HEROS & RODOS manufactured by SYMPATEC) was used. The dispersion pressure of the dry dispersion unit was 5.0 bar, the degree of vacuum was 5.0 mbar, and the measurement was performed by the dry measurement method, and the D50 value was taken as the average particle diameter.

[Measurement of water content]
The measurement was performed using a Karl Fischer titer (MKA-510N type, Kyoto Denshi Kogyo Co., Ltd.) as a measuring device.

[Calculation method of internal pressure of thermally expandable microspheres]
For the internal pressure of the heat-expandable microspheres at 140 ° C. or 250 ° C., the mole fraction of each hydrocarbon constituting the foaming agent is calculated from the blending amount of each hydrocarbon constituting the foaming agent, and each hydrocarbon constituting the foaming agent is calculated. Multiply the vapor pressures of hydrogen at 140 ° C and 250 ° C by the calculated mole fractions of each hydrocarbon, and add up the multiplied values to calculate the vapor pressures of the foaming agent at 140 ° C and 250 ° C. The internal pressure of the expanding microspheres at 140 ° C. or 250 ° C. was used.
Isopentane: vapor pressure at 140 ° C. 1.5 MPa, vapor pressure at 250 ° C. 6.4 MPa, molecular weight 72
Isohexane: vapor pressure at 140 ° C. 0.73 MPa, vapor pressure at 250 ° C. 3.8 MPa, molecular weight 86
Isooctane: vapor pressure at 140 ° C. 0.28 MPa, vapor pressure at 250 ° C. 1.8 MPa, molecular weight 114
Isododecan: Vapor pressure 0.45 MPa at 250 ° C., molecular weight 170
Isohexadecane: molecular weight 226
Since the vapor pressure of isododecane at 140 ° C and the vapor pressure of isohexadecane at 140 ° C and 250 ° C are very low, the vapor pressure of isododecane at 140 ° C and the vapor pressure of isohexadecane at 140 ° C and 250 ° C are set to substantially 0 MPa for thermal expansion. The vapor pressure of the inclusion component of sex microspheres was calculated.

[Measurement of expansion start temperature (Ts) and maximum expansion temperature (Tmax)]
As a measuring device, DMA (DMA Q800 type, manufactured by TA instruments) was used. Place 0.5 mg of microspheres in an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and place an aluminum lid (diameter 5.6 mm, 0.1 mm) on the top of the microsphere layer to place the sample. Got ready. The height of the sample was measured with a force of 0.01 N applied to the sample from above with a pressurizer. With a force of 0.01 N applied by the pressurizer, the pressurizer was heated from 20 ° C. to 300 ° C. at a heating rate of 10 ° C./min, and the amount of displacement of the pressurizer in the vertical direction was measured. The displacement start temperature in the positive direction was defined as the expansion start temperature (Ts), and the temperature when the maximum displacement amount was indicated was measured as the maximum expansion temperature (Tmax).

[Expansion magnification]
A value obtained by dividing the specific gravity of the molded product formed without containing the thermally expanded microspheres by the specific gravity of the foamed molded product was calculated and used as the expansion ratio. The specific gravity of the molded product was measured by a method based on the K-7112 A method (underwater substitution method).

[State of bubbles]
Using an electron microscope (SEM) device, the state of bubbles in the cross section of the obtained molded product was confirmed. The ratio of closed cells to the unit area is calculated from the SEM photograph taken at 30 times, and the judgment is made based on the following evaluation criteria.
⊚: Uniformly independent (closed cell ratio 80% or more)
◯: Almost uniformly independent (closed cell ratio is 50% or more and less than 80%)
X: Non-uniform (closed cell ratio is less than 50%)

[Bubble diameter]
It was calculated by a method according to ASTM D3576-77 from an SEM photograph of the cross section of the obtained molded product taken at 100 times.

[Surface condition]
The obtained foamed molded product was prepared to have a width of 15 cm and a length of 50 cm, and the prepared foamed molded product was visually confirmed and judged based on the following evaluation criteria.
◯: Good (there are less than 5 dents due to the destruction of thermally expandable microspheres, and there is no surface roughness.)
Δ: Slightly defective (a state in which there are 5 or more and less than 15 dents due to the destruction of thermally expandable microspheres, and some surface roughness is observed).
X: Defective (a state in which there are 5 or more and less than 15 dents due to the destruction of the heat-expandable microspheres, and the surface is rough as a whole).

[Ratio of bubble volume to inorganic filler volume]
The weight of the base material component (including the base material component contained in the master batch of the inorganic filler and the heat-expandable microspheres) and the inorganic filler to be blended in the resin composition for foam molding is determined by the base material component and the inorganic filler. The value divided by each density was calculated as the volume of the base material component and the inorganic filler, and the calculated volume values were added up. The value of the volume of bubbles in the foamed molded product was calculated by multiplying the value of the total volume by the value obtained by subtracting 1 from the foaming magnification of the foamed molded product calculated by the above method. Taking the calculated volume value of the inorganic filler as 1, and dividing the calculated volume value of the bubbles by the volume value of the inorganic filler, the calculated value is the volume of the bubbles and the volume of the inorganic filler in the foamed molded product. It was the ratio of. The densities of the base material components and the inorganic filler are as follows.
Ethylene-vinyl acetate (EVA) resin: density 0.93 g / cm ³
Polyethylene resin: Density 0.94 g / cm ³
Acid-modified polyethylene resin: Density 0.94 g / cm ³
Polypropylene resin: Density 0.90 g / cm ³
Acid-modified polypropylene resin: Density 0.90 g / cm ³
Calcium carbonate: Density 2.7 g / cm ³
Talc: Density 2.7 g / cm ³

[Preparation of thermally expandable microspheres]
[Manufacturing Example 1]
To 600 g of ion-exchanged water, 120 g of sodium chloride, 50 g of colloidal silica which is 20% by weight of the silica active ingredient, 3 g of diethanolamine-azipic acid condensate and 0.1 g of ethylenediaminetetraacetic acid / 4Na salt in a 5% aqueous solution were added, and the pH was adjusted to 2. The composition was adjusted to 8 to 3.2 to prepare an aqueous dispersion medium.
Separately, 155 g of acrylonitrile, 79 g of methacrylonitrile, 15 g of methyl methacrylate, 1 g of ethylene glycol dimethacrylate, 1.5 g of 2-2'-azobis (2-methylpropionitrile), 30 g of isopentane, 25 g of isooctane, and isododecane. 15 g was mixed to prepare an oily mixture.
The aqueous dispersion medium and the oily mixture were mixed, and the obtained mixture was dispersed by a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension. This suspension was transferred to a pressure reactor having a capacity of 1.5 liters for nitrogen substitution, and then the initial reaction pressure was 0.5 MPa, and the mixture was polymerized at a polymerization temperature of 60 ° C. for 20 hours while stirring at 80 rpm. The heat-expandable microspheres obtained by filtering and drying the polymerization liquid obtained after the polymerization were designated as microspheres 1. Table 1 shows the physical characteristics of the obtained microspheres 1.

[Production Examples 2 to 20]
Microspheres 2 to 20 were obtained in the same manner as in Production Example 1 except that the various components and amounts used in Production Example 1 were changed to those shown in Tables 1 and 2. The physical characteristics of the obtained microspheres 2 to 20 are shown in Tables 1 and 2. The details of the abbreviations of the various components in Tables 1 and 2 are shown in Table 3.

[Preparation of masterbatch of heat-expandable microspheres]
50 parts by weight of heat-expandable microspheres 1 and 2 parts by weight of fluid paraffin oil (P-200) and 48 parts by weight of ethylene-vinyl acetate (EVA) resin are blended with a ribbon mixer, and Labplast Mill (Toyo Seiki) Manufactured by the company; the cylinder temperature and the die temperature were all 100 ° C., and the screw rotation speed was 30 rpm), and the mixture was extruded into a strand shape having a diameter of 2 mm. The obtained strands were air-cooled, and then pelletized into bale-shaped pellets having a length of 4 mm with a pelletizer to obtain a master batch 1 (MB1) containing 50% by weight of heat-expandable microspheres 1.
Further, master batches 2 to 20 (MB2 to 20) were obtained in the same manner as in the preparation of MB1 except that the heat-expandable microspheres 1 were changed to the heat-expandable microspheres 2 to 20.

[Adjustment of masterbatch of inorganic filler]
75 parts by weight of calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., PO-120-B-10, average particle size 1.8 μm), 5 parts by weight of polyethylene resin (manufactured by Japan Polyethylene Corporation, Novatec LL UJ960, melting point: 126 ° C.) and 20 parts by weight of acid-modified polyethylene resin (manufactured by Japan Polyethylene Corporation, Lexpearl ET230X, melting point: 99 ° C) is blended with a ribbon mixer, and Labplast Mill (manufactured by Toyo Seiki Co., Ltd .; cylinder temperature and die temperature are all 165 ° C, screw. It was extruded into a strand shape having a diameter of 2 mm using a rotation speed of 20 rpm). The obtained strands were air-cooled, and then pelletized into bale-shaped pellets having a length of 4 mm with a pelletizer to obtain an inorganic filler masterbatch 1 containing 75% by weight of calcium carbonate, which is an inorganic filler.

[Example 1-1]
100 parts by weight of inorganic filler masterbatch 1 (containing 75% by weight of calcium carbonate), 40 parts by weight of polyethylene resin (manufactured by Japan Polyethylene Corporation, Novatec LL UJ960), 5 parts by weight of heat-expandable microspheres 1 masterbatch ( MB1) was mixed in advance with a ribbon mixer to obtain a foam molding composition. The content of the inorganic filler in the obtained composition for foam molding was 52% by weight, and the content of the heat-expandable microspheres with respect to 100 parts by weight of the inorganic filler was 3.3 parts by weight.
The obtained mixture of the foam molding composition is supplied from the raw material supply port of Labo Plast Mill (manufactured by Toyo Seiki Co., Ltd.), which is an extrusion molding machine, and the temperature of the kneaded product in the cylinder (molding temperature of the foam molding product) is adjusted. The temperature of the T-die (width 150 mm, lip thickness 1.7 mm) was set to 190 ° C., and the melt mixture was extruded at a screw rotation speed of 40 rpm to obtain a plate-shaped foam molded product (width 148 mm, thickness 1.7 mm).
The bubble state, bubble diameter, surface condition, foaming ratio, and ratio of bubble volume to inorganic filler volume (bubble: inorganic filler) of the obtained foamed molded product were evaluated. The results are shown in Table 4.

[Examples 1-2 to 1-14, Comparative Examples 1-1 to 1-6]
In Example 1-1, the masterbatch of the heat-expandable microspheres to be used and the blending amount thereof, the blending amount of the polyethylene resin, the temperature of the kneaded product in the cylinder (molding temperature of the foam molded product), and the temperature of the T die were determined. Each foam molding composition and each foam molding body were obtained in the same manner as in Example 1-1 except that the changes were changed to those shown in Tables 4 and 5. For each of the obtained foamed molded products, the bubble state, bubble diameter, surface condition, foaming ratio, and the ratio of the volume of bubbles to the volume of the inorganic filler (bubbles: inorganic filler) were evaluated. The results are shown in Tables 4 and 5.

[Adjustment of masterbatch of inorganic filler]
75 parts by weight of talc (manufactured by Nippon Tarku, Micro Ace P-3, average particle size 5.0 μm), 5 parts by weight of polypropylene resin (manufactured by Japan Polypropylene, Novatec PP MA3H, softening point: 110 ° C) and 20 weight The acid-modified polypropylene resin (manufactured by Sanyo Kasei Co., Ltd., Umex 1010, softening point: 145 ° C) is blended with a ribbon mixer, and Labplast Mill (manufactured by Toyo Seiki Co., Ltd .; cylinder temperature and die temperature are all 220 ° C., screw rotation speed. It was extruded into a strand shape having a diameter of 2 mm using 20 rpm). The obtained strands were air-cooled and then pelletized into bale-shaped pellets having a length of 4 mm with a pelletizer to obtain an inorganic filler masterbatch 2 containing 75% by weight of talc, which is an inorganic filler.

[Example 2-1]
100 parts by weight of inorganic filler masterbatch 2 (containing 75% by weight of talc), 40 parts by weight of polypropylene resin (manufactured by Japan Polypropylene Corporation, Novatec PP MA3H, softening point: 110 ° C.), 5 parts by weight of thermally expandable microspheres The master batch (MB7) of No. 7 was mixed in advance with a ribbon mixer to obtain a foam molding composition. The content of the inorganic filler in the obtained composition for foam molding was 52% by weight, and the content of the heat-expandable microspheres with respect to 100 parts by weight of the inorganic filler was 3.3 parts by weight.
The obtained mixture of the foam molding composition is supplied from the raw material supply port of Labo Plast Mill (manufactured by Toyo Seiki Co., Ltd.), which is an extrusion molding machine, and the temperature of the kneaded product in the cylinder (molding temperature of the foam molding product) is adjusted. The temperature of the T-die (width 150 mm, lip thickness 1.7 mm) was set to 230 ° C., and the melt mixture was extruded at a screw rotation speed of 40 rpm to obtain a plate-shaped foam molded product (width 149 mm, thickness 1.7 mm).
For each of the obtained foamed molded products, the bubble state, bubble diameter, surface condition, foaming ratio, and the ratio of the volume of bubbles to the volume of the inorganic filler (bubbles: inorganic filler) were evaluated. The results are shown in Table 6.

[Examples 2-2 to 2-14, Comparative Examples 2-1 to 2-6]
In Example 2-1 the masterbatch of the heat-expandable microspheres to be used and the blending amount thereof, the blending amount of polypropylene resin, the temperature of the kneaded product in the cylinder (molding temperature of the foam molded product), and the temperature of the T die were determined. Each foam molding composition and each foam molding body were obtained in the same manner as in Example 2-1 except for the changes to those shown in Tables 6 and 7. The moldability, air bubble state, surface state, and foaming ratio of each of the obtained foamed molded products were evaluated. The results are shown in Tables 6 and 7.

As can be seen from Tables 4 to 7, the content of the inorganic filler is 20 to 70% by weight, the internal pressure of the heat-expandable microspheres contained at 140 ° C. is 0.6 to 1.4 MPa, and the internal pressure at 250 ° C. is 3 to 3. The foamed molded product of the example obtained by using the foam molding composition having a value of 6.2 MPa has an inorganic filler content of 20 to 70% by weight, and the internal pressure of the heat-expandable microspheres contained at 140 ° C. Compared with the foamed molded product of the comparative example obtained under the condition that the internal pressure at 0.6 to 1.4 MPa and 250 ° C. does not satisfy any of 3 to 6.2 MPa, the bubble state, surface state, and expansion coefficient It can be seen that both are excellent.

11 Outer shell made of thermoplastic resin 12 Foaming agent

Claims (8)

For foam molding containing a heat-expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent contained therein and vaporized by heating, a base material component excluding a vinyl chloride resin, and an inorganic filler. It ’s a composition,
The weight ratio of the inorganic filler to the foam molding composition is 40 to 70% by weight.
The thermoplastic resin is a polymer of a polymerizable component containing a nitrile-based monomer.
The nitrile-based monomer contains acrylonitrile and / or methacrylonitrile.
The internal pressure of the heat-expandable microspheres at 140 ° C. is 0.6 to 1.4 MPa, and the internal pressure of the heat-expandable microspheres at 250 ° C. is 3 to 6.2 MPa.
Composition for foam molding. The foam molding composition according to claim 1, wherein the weight ratio of the heat-expandable microspheres is 1 to 20 parts by weight with respect to 100 parts by weight of the inorganic filler. The composition for foam molding according to claim 1 or 2 , wherein the polymerizable component further contains a carboxyl group-containing monomer. The foam molding composition according to claim 1 or 2, wherein the polymerizable component further contains a carboxyl group-containing monomer and / or a (meth) acrylic acid ester-based monomer . The composition for foam molding according to any one of claims 1 to 4, wherein the expansion start temperature of the heat-expandable microspheres is 140 to 200 ° C. The inorganic filler is magnesium hydroxide, aluminum hydroxide, calcium hydroxide, silica, alumina, titanium oxide, magnesium oxide, calcium oxide, zinc oxide, antimony trioxide, antimone pentoxide, calcium sulfate, barium sulfate, potassium carbonate. , Calcium carbonate, magnesium carbonate, aluminum silicate, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, calcium aluminum silicate, talc, mica, wallastnite, glass beads and carbon black. The composition for foam molding according to any one of claims 1 to 5, which is one type. A foam molded product obtained by molding the foam molding composition according to any one of claims 1 to 6. The foamed molded product according to claim 7, wherein the ratio of the volume of bubbles to the volume of the inorganic filler (bubbles: inorganic filler) in the foamed molded product is 0.5: 1 to 23: 1.

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