JP5740464B2 - Foamable composition and method for producing foamed molded article - Google Patents

Description

The present invention relates to a foamable composition that is less susceptible to particle rupture and shrinkage even when heated at high temperatures and can be used for foam molding at a high foaming ratio. Moreover, this invention relates to the manufacturing method of the foaming molding using the said foamable composition.

Plastic foam can exhibit heat insulation, heat insulation, sound insulation, sound absorption, vibration insulation, weight reduction, etc. depending on the foam material and the state of the formed bubbles, so it can be used in various applications. It is used. As a method for producing a plastic foam, for example, a resin composition containing a matrix resin such as a thermoplastic resin and a foaming agent, a masterbatch, and the like are molded using a molding method such as injection molding or extrusion molding, and then molded. The method of making a foaming agent foam by the heating of time is mentioned.

When manufacturing a plastic foam, for example, a chemical foaming agent, thermally expandable foamed particles, and the like are used as the foaming agent.
For example, Patent Document 1 describes foamable pellets obtained by kneading and molding at least an ethylene-α-olefin copolymer and a foaming agent. As the foaming agent, an azo compound, a hydrazine derivative, Carbonates and the like are mentioned. In Patent Document 1, when foamable pellets described in the same document are used, it is possible to perform injection foam molding at a high expansion ratio regardless of the type of resin, and to obtain an injection foam molded body with uniform hardness and various bubbles. It is described that

However, when such a chemical foaming agent is used, the walls of the bubbles are formed by the matrix resin, and the thin portion of the wall may rupture, resulting in open cells or variations in the wall thickness. For this reason, it is difficult to obtain a foam having uniform closed cells. Further, when the chemical foaming agent is thermally decomposed to generate decomposition gas, a foaming residue is generated at the same time, which may affect the performance of the resulting foam.

On the other hand, as the thermally expandable foam particles used as a foaming agent, for example, particles obtained by encapsulating a volatile swelling agent that becomes gaseous at a temperature below the softening point of the shell polymer in a thermoplastic shell polymer. Is mentioned. For example, in Patent Document 2, by using a masterbatch containing a thermally expandable microballoon, a thermoplastic elastomer foam having uniform and fine particle diameter cells and excellent physical property uniformity and mechanical properties is disclosed. It is described that a body is obtained.

However, the expanded particles obtained by this method can be thermally expanded at a relatively low temperature of about 80 to 130 ° C. due to the volatile expansion agent becoming a gas. The foaming ratio decreases due to the loss of the foam. Further, if the heat resistance or strength of the expanded particles is insufficient, a phenomenon called “sag” occurs, and the foamed particles may be crushed at a high temperature. Therefore, when such foamed particles are used, it is difficult to perform molding at a high expansion ratio when a molding process at a high temperature is required, and there is a problem that applicable applications are limited.

JP 2000-178372 A Japanese Patent Laid-Open No. 11-343362

An object of the present invention is to provide a foamable composition that is less likely to be ruptured and shrunk even when heated at a high temperature and can be used for foam molding at a high foaming ratio. Moreover, an object of this invention is to provide the manufacturing method of the foaming molding using the said foamable composition.

The present invention relates to a foamable composition comprising foamed particles and a curing agent capable of reacting with an epoxy group, wherein the foamed particles contain a volatile swelling agent as a core agent in a shell made of a copolymer. and it is, the copolymer has a nitrile monomer, is obtained by copolymerizing a monomer mixture containing an epoxy group-containing monomer having at least one polymerizable unsaturated bond, the nitrile monomer 100 wt It is a foamable composition containing 1 to 30 parts by weight of an epoxy group-containing monomer having at least one polymerizable unsaturated bond with respect to parts .
The present invention is described in detail below.

In the foamable composition containing foamed particles containing a volatile swelling agent as a core agent in a shell made of a copolymer, the present inventors obtain a copolymer constituting the shell from a specific monomer mixture. By adding a curing agent capable of reacting with an epoxy group, it is possible to obtain a foamable composition that can be used for foam molding at a high foaming ratio without causing particle rupture and shrinkage even when heated at a high temperature. As a result, the present invention has been completed.

The foamed particles according to the present invention include a volatile swelling agent as a core agent in a shell made of a copolymer.
Due to having such a structure, when the foamed particles according to the present invention are blended and molded into a matrix resin, the core agent becomes gaseous by heating during molding and the shell softens and expands, that is, The foamed particles according to the present invention can be foamed to produce a foamed molded article.

The copolymer constituting the shell is obtained by copolymerizing a monomer mixture.
The monomer mixture contains a nitrile monomer.
The nitrile monomer is not particularly limited, and examples thereof include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, or a mixture thereof. Of these, acrylonitrile and methacrylonitrile are particularly preferred. These may be used independently and 2 or more types may be used together.

The monomer mixture contains an epoxy group-containing monomer having at least one polymerizable unsaturated bond.
The epoxy group-containing monomer having at least one polymerizable unsaturated bond is not particularly limited as long as it has at least one polymerizable unsaturated bond and an epoxy group in the molecule. One or two epoxy group-containing monomers are preferred.

The epoxy group-containing monomer having one polymerizable unsaturated bond is not particularly limited, and examples thereof include glycidyl methacrylate, glycidyl acrylate, and phenol type epoxy acrylate. Of these, glycidyl methacrylate is preferred. These may be used independently and 2 or more types may be used together.

The epoxy group-containing monomer having two polymerizable unsaturated bonds is not particularly limited, and is allyl alcohol type epoxy diacrylate, 1,6-hexanediol type epoxy diacrylate, bisphenol type epoxy diacrylate, phthalic acid type epoxy diester. Examples include acrylate, polypropylene glycol type epoxy diacrylate (n = 1, 3, 11), polyethylene glycol type epoxy dimethacrylate (n = 1, 2, 9), and the like. Among these, polypropylene glycol type epoxy diacrylate (n = 1, 3, 11) is preferable. These may be used independently and 2 or more types may be used together.

The content of the epoxy group-containing monomer having at least one polymerizable unsaturated bond in the monomer mixture is not particularly limited, but a preferable lower limit with respect to 100 parts by weight of the nitrile monomer is 0.5 parts by weight, and a preferable upper limit is 30. Parts by weight. When the content of the epoxy group-containing monomer having at least one polymerizable unsaturated bond is less than 0.5 parts by weight, when the foamed particles obtained are molded into a matrix resin and molded, when heated at a high temperature during molding Particle rupture and shrinkage may occur easily. When the content of the epoxy group-containing monomer having at least one polymerizable unsaturated bond exceeds 30 parts by weight, the resulting foamed particles may have a deteriorated gas barrier property of the shell and a foaming performance. As for the content of the epoxy group-containing monomer having at least one polymerizable unsaturated bond, a more preferable lower limit with respect to 100 parts by weight of the nitrile monomer is 1 part by weight, and a more preferable upper limit is 20 parts by weight.

The monomer mixture contains the nitrile monomer and another monomer that can be copolymerized with the epoxy group-containing monomer having at least one polymerizable unsaturated bond (hereinafter also simply referred to as another monomer). May be.
The other monomers are not particularly limited and can be appropriately selected according to the characteristics required for the obtained expanded particles. For example, divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate , Triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di ( (Meth) acrylate, di (meth) acrylate of polyethylene glycol having a molecular weight of 200 to 600, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide modification Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, triallyl formal tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dimethylol-tricyclodecandi ( And (meth) acrylate. Examples of the other monomers include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid, and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and citraconic acid. Acrylic acid esters such as acid, methyl acrylate, ethyl acrylate, butyl acrylate, and dicyclopentenyl acrylate; and methacrylate esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and isobornyl methacrylate; And vinyl monomers such as vinyl chloride, vinylidene chloride, vinyl acetate, and styrene.
These may be used independently and 2 or more types may be used together. Among these, acrylic acid, methacrylic acid, maleic acid or maleic anhydride, and itaconic acid are particularly preferable.

When the monomer mixture contains the other monomer, the content of the other monomer in the monomer mixture is not particularly limited, but a preferable upper limit with respect to 100 parts by weight of the nitrile monomer is 40 parts by weight. When the content of the other monomer exceeds 40 parts by weight, the content of the nitrile monomer or the epoxy group-containing monomer having at least one polymerizable unsaturated bond is decreased, and the obtained expanded particles are used. In some cases, foam molding cannot be performed at a high expansion ratio.

The monomer mixture may contain a metal cation salt.
By containing the metal cation, for example, the carboxyl group of the carboxyl group-containing monomer in the monomer mixture such as methacrylic acid and the metal cation form an ionic crosslink, and the resulting expanded particles have a cross-linking efficiency of the shell. And heat resistance is improved. Therefore, when such foamed particles are blended with a matrix resin and molded, even if heated at a high temperature during molding, the particles are unlikely to burst and shrink, and foam molding can be performed at a high foaming ratio using the particles. it can. Moreover, the foamed particles obtained by forming the ionic crosslinks are less likely to have a lower elastic modulus of the shell even at high temperatures. Therefore, when such foamed particles are blended with a matrix resin and molded, even when using a molding method such as kneading molding, calender molding, extrusion molding, injection molding, or the like in which a strong shear force is applied, the particles are unlikely to burst and shrink. Using the particles, foam molding can be performed at a high expansion ratio.

The metal cation forming the metal cation salt is not particularly limited as long as it is a metal cation capable of forming an ionic bridge with the carboxyl group of the carboxyl group-containing monomer in the monomer mixture such as methacrylic acid, for example, Examples of the ions include Na, K, Li, Zn, Mg, Ca, Ba, Sr, Mn, Al, Ti, Ru, Fe, Ni, Cu, Cs, Sn, Cr, and Pb. Among these, ions of Ca, Zn, and Al, which are divalent to trivalent metal cations, are preferable, and Zn ions are particularly preferable.
The metal cation salt is preferably a hydroxide of the metal cation. These metal cation salts may be used independently and 2 or more types may be used together.

When two or more of the above metal cation salts are used in combination, for example, a salt composed of an alkali metal or alkaline earth metal ion and a salt composed of a metal cation other than the alkali metal or alkaline earth metal may be used in combination. preferable. The alkali metal or alkaline earth metal ion can activate a functional group such as a carboxyl group, and an ion between the functional group such as the carboxyl group and a metal cation other than the alkali metal or alkaline earth metal. Cross-linking can be promoted.
The alkali metal or alkaline earth metal is not particularly limited, and examples thereof include Na, K, Li, Ca, Ba, and Sr. Of these, strong basic Na and K are preferred.

When the monomer mixture contains the metal cation salt, the content of the metal cation salt in the monomer mixture is not particularly limited, but a preferred lower limit to 100 parts by weight of the nitrile monomer is 0.1 part by weight, and a preferred upper limit. Is 10 parts by weight. When the content of the metal cation salt is less than 0.1 parts by weight, the effect of improving the heat resistance of the obtained expanded particles may not be sufficiently obtained. When the content of the metal cation salt exceeds 10 parts by weight, the foamed product may have a significantly reduced foaming ratio when the foamed particles obtained are blended with a matrix resin and molded.

The monomer composition preferably contains a polymerization initiator.
The polymerization initiator is not particularly limited, and examples thereof include dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, and azo compound.
The dialkyl peroxide is not particularly limited, and examples thereof include methyl ethyl peroxide, di-t-butyl peroxide, dicumyl peroxide, isobutyl peroxide and the like.

The diacyl peroxide is not particularly limited, and examples thereof include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, and the like.
The peroxy ester is not particularly limited, and examples thereof include t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1- Cyclohexyl-1-methylethylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, cumylperoxyneodecanoate, (α, α-bis-neodecanoylper And oxy) diisopropylbenzene.
The peroxydicarbonate is not particularly limited. For example, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl-peroxydicarbonate, diisopropyl peroxydicarbonate, di (2-ethylethyl) Peroxy) dicarbonate, dimethoxybutyl peroxydicarbonate, di (3-methyl-3-methoxybutylperoxy) dicarbonate, and the like.
The azo compound is not particularly limited. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis ( 2,4-dimethylvaleronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile) and the like.

The monomer mixture may further contain a stabilizer, an ultraviolet absorber, an antioxidant, an antistatic agent, a flame retardant, a silane coupling agent, a colorant and the like, if necessary.

By copolymerizing the monomer mixture as described above, a copolymer constituting the shell of the expanded particles according to the present invention can be obtained.
The weight average molecular weight of the copolymer is not particularly limited, but a preferable lower limit is 100,000 and a preferable upper limit is 2 million. When the weight average molecular weight is less than 100,000, the foamed particles obtained have a reduced shell strength, and if the particles are used, foam molding may not be performed at a high expansion ratio. When the weight average molecular weight exceeds 2,000,000, the foamed particles obtained have a shell strength that is too high, and foaming performance may deteriorate.

The foamed particles according to the present invention may be subjected to a surface treatment with a curing agent whose surface of the shell can react with an epoxy group.
Conventionally, when foamed particles used in the production of foamed molded products are heated at a high temperature during molding, the expansion ratio is reduced due to the escape of gas from the expanded particles, or a phenomenon called so-called “sagging” occurs and the material is crushed. In some cases, it was difficult to perform foam molding at a high expansion ratio.

On the other hand, the foamed particles according to the present invention are foamed by heating at the time of molding when the shell surface is treated with a curing agent capable of reacting with the epoxy group and molded into a matrix resin. At the same time, the epoxy group present on the surface of the shell and the curing agent capable of reacting with the epoxy group present on the surface of the shell react to cure the surface of the shell and fix the foamed state. . Thereby, even if the foamed particle which concerns on this invention is heated at high temperature at the time of shaping | molding, it is hard to produce a particle burst and shrinkage | contraction, and it can foam-mold at a high foaming ratio using the foamed particle which concerns on this invention.
In addition, an epoxy group can exist on the surface of the shell by using the epoxy group-containing monomer having at least one polymerizable unsaturated bond as a monomer constituting the shell.

The method for surface treatment with the curing agent capable of reacting with the epoxy group is not particularly limited, and the treatment can be performed by a general heating and stirring method.

When the surface of the shell is surface-treated with a curing agent capable of reacting with the epoxy group, the amount of the curing agent capable of reacting with the epoxy group is not particularly limited, but the epoxy having at least one polymerizable unsaturated bond is not limited. The preferred lower limit is 0.5 times the amount and the preferred upper limit is 5 times the theoretical hardener amount relative to the epoxy equivalent of the group-containing monomer. When the amount of the curing agent capable of reacting with the epoxy group is less than 0.5 times, when foamed particles obtained are molded into a matrix resin and heated at a high temperature during molding, the particles burst and shrink. May occur easily. When the addition amount of the curing agent capable of reacting with the epoxy group exceeds 5 times, the reaction between the epoxy group present on the surface of the shell at the surface treatment stage and the curing agent capable of reacting with the epoxy group proceeds. Thus, the foamed particles may be cured at the surface treatment stage before foaming.

The expanded particles according to the present invention include a volatile swelling agent as a core agent.
In the present specification, the volatile swelling agent refers to a substance that becomes gaseous at a temperature below the softening point of the copolymer constituting the shell of the expanded particles according to the present invention.
Although the volatile swelling agent is not particularly limited, a low boiling point organic solvent is preferable, and specifically, for example, ethane, ethylene, propane, propene, n-butane, isobutane, butene, isobutene, n-pentane, isopentane, neopentane. , hexane n-, heptane, low molecular weight hydrocarbons such as petroleum _{ether, CCl 3 F, CCl 2 F} 2, CClF 3, CClF 2 -CClF 2 such chlorofluorocarbons, tetramethylsilane, trimethylethyl silane, trimethyl isopropyl silane And tetraalkylsilanes such as trimethyl-n-propylsilane. Among these, by using isobutane, n-butane, n-pentane, isopentane, n-hexane, petroleum ether, or a mixture thereof, the foaming ratio is high and the particles start to foam quickly. Can do. These volatile swelling agents may be used alone or in combination of two or more.
Further, as the volatile expansion agent, a thermally decomposable compound that is thermally decomposed by heating and becomes gaseous may be used.

Although content of the said volatile expansion | swelling agent in the expanded particle which concerns on this invention is not specifically limited, A preferable minimum is 10 weight% and a preferable upper limit is 25 weight%. When the content of the volatile swelling agent is less than 10% by weight, the foamed particles obtained may have a too thick shell and the foaming performance may deteriorate. When the content of the volatile expansion agent exceeds 25% by weight, the foamed particles obtained have a reduced shell strength, and when these particles are used, foam molding may not be performed at a high expansion ratio.

The maximum foaming temperature (Tmax) of the foamed particles according to the present invention is not particularly limited, but a preferred lower limit is 200 ° C. When the maximum foaming temperature is less than 200 ° C., the foamed particles have low heat resistance, and when heated at a high temperature during molding, the particles may easily burst and shrink. In addition, when the maximum foaming temperature is less than 200 ° C., when producing master batch pellets using foamed particles, foaming occurs due to the shearing force at the time of pellet production, which stabilizes the unfoamed master batch pellets. Cannot be manufactured. The more preferable lower limit of the maximum foaming temperature of the foamed particles is 210 ° C.
In the present specification, the maximum foaming temperature means a temperature when the diameter of the foamed particles is measured while the foamed particles are heated from room temperature and the maximum displacement is obtained.

The volume average particle diameter of the expanded particles according to the present invention is not particularly limited, but a preferable lower limit is 10 μm and a preferable upper limit is 50 μm. When the volume average particle diameter is less than 10 μm, when foamed particles are blended into a matrix resin and molded, the foamed molded body obtained has too small bubbles, which may result in insufficient weight reduction. If the volume average particle diameter exceeds 50 μm, when foamed particles are blended with a matrix resin and molded, the foamed foam obtained is too large, which may cause problems in terms of strength and the like. The volume average particle diameter has a more preferable lower limit of 15 μm and a more preferable upper limit of 40 μm.

The method for producing the expanded particles according to the present invention is not particularly limited. For example, the step of preparing an aqueous dispersion medium, and an oily liquid mixture containing the monomer mixture and the volatile swelling agent in the aqueous dispersion medium. And a step of copolymerizing the monomer mixture to obtain particles containing a volatile swelling agent as a core agent in a shell made of a copolymer, and then, if necessary, the particles The method of performing the process of surface-treating with the hardening | curing agent which can react with the epoxy group as mentioned above etc. is mentioned.

In the step of preparing the aqueous dispersion medium, for example, an aqueous dispersion medium containing the dispersion stabilizer is prepared by adding water, a dispersion stabilizer, and, if necessary, an auxiliary stabilizer to the polymerization reaction vessel. Moreover, you may add alkali metal nitrite, stannous chloride, stannic chloride, potassium dichromate, etc. to the said aqueous dispersion medium as needed.

The dispersion stabilizer is not particularly limited. For example, silica, calcium phosphate, magnesium hydroxide, aluminum hydroxide, ferric hydroxide, barium sulfate, calcium sulfate, sodium sulfate, calcium oxalate, calcium carbonate, calcium carbonate, carbonate Examples include barium and magnesium carbonate.

The auxiliary stabilizer is not particularly limited, and examples thereof include a condensation product of diethanolamine and an aliphatic dicarboxylic acid, a condensation product of urea and formaldehyde, a water-soluble nitrogen-containing compound, polyethylene oxide, tetramethylammonium hydroxide, gelatin, Examples include methyl cellulose, polyvinyl alcohol, dioctyl sulfosuccinate, sorbitan ester, and various emulsifiers.
The water-soluble nitrogen-containing compound is not particularly limited, for example, polyvinyl pyrrolidone, polyethyleneimine, polyoxyethylene alkylamine, polydialkylaminoalkyl (meth) acrylate represented by polydimethylaminoethyl methacrylate and polydimethylaminoethyl acrylate, Examples thereof include polydialkylaminoalkyl (meth) acrylamide, polyacrylamide, polycationic acrylamide, polyamine sulfone, polyallylamine and the like typified by polydimethylaminopropyl acrylamide and polydimethylaminopropyl methacrylamide. Of these, polyvinylpyrrolidone is preferred.

The combination of the dispersion stabilizer and the auxiliary stabilizer is not particularly limited. For example, a combination of colloidal silica and a condensation product, a combination of colloidal silica and a water-soluble nitrogen-containing compound, magnesium hydroxide or calcium phosphate and an emulsifier. And the like. Among these, a combination of colloidal silica and a condensation product is preferable, and the condensation product is preferably a condensation product of diethanolamine and an aliphatic dicarboxylic acid, a condensation product of diethanolamine and adipic acid, diethanolamine and A condensation product with itaconic acid is particularly preferred.

When colloidal silica is used as the dispersion stabilizer, the amount of colloidal silica added is not particularly limited and can be appropriately determined depending on the particle diameter of the desired foamed particles, but the preferred lower limit for 100 parts by weight of the total monomer component is 1 Part by weight, a preferred upper limit is 20 parts by weight, a more preferred lower limit is 2 parts by weight, and a more preferred upper limit is 10 parts by weight.
In addition, when the condensation product or the water-soluble nitrogen-containing compound is used as the auxiliary stabilizer, the addition amount of the condensation product or the water-soluble nitrogen-containing compound is not particularly limited, and depends on the particle diameter of the target expanded particles. Although it can be suitably determined, the preferable lower limit with respect to 100 parts by weight of all monomer components is 0.05 part by weight, and the preferable upper limit is 2 parts by weight.

In addition to the dispersion stabilizer and the auxiliary stabilizer, an inorganic salt such as sodium chloride or sodium sulfate may be further added to the aqueous dispersion medium. By adding such an inorganic salt, expanded particles having a more uniform particle shape can be obtained.
The amount of the inorganic salt added is not particularly limited, but the preferable upper limit with respect to 100 parts by weight of all monomer components is 100 parts by weight.

The aqueous dispersion medium is prepared by blending the dispersion stabilizer and the auxiliary stabilizer with deionized water, and the pH of the deionized water is appropriately determined according to the type of the dispersion stabilizer and auxiliary stabilizer used. Can do. For example, when silica such as colloidal silica is used as the dispersion stabilizer, an acid such as hydrochloric acid is added as necessary to adjust the pH of the system to 3 to 4, and polymerization can be performed under acidic conditions in the steps described later. Done. When magnesium hydroxide or calcium phosphate is used as the dispersion stabilizer, the system is adjusted to be alkaline, and polymerization is performed under alkaline conditions in the steps described later.

In the method for producing expanded particles according to the present invention, a step of dispersing an oily mixed solution containing the monomer mixture and the volatile swelling agent in the aqueous dispersion medium is then performed.
In the step of dispersing the oily mixture containing the monomer mixture and the volatile swelling agent in the aqueous dispersion medium, the monomer mixture and the volatile swelling agent are separately added to the aqueous dispersion medium. The oily mixed solution may be prepared in the aqueous dispersion medium, but usually, both are mixed in advance to obtain an oily mixed solution, and then added to the aqueous dispersion medium. At this time, the oil-based mixed liquid and the aqueous dispersion medium are prepared in separate containers in advance, and the oil-based mixed liquid is dispersed in the aqueous dispersion medium by mixing with stirring in another container, and then the polymerization reaction container. It may be added.
A polymerization initiator is used to polymerize the monomers in the monomer mixture. However, the polymerization initiator may be added to the oily mixture in advance, and the aqueous dispersion medium and the oily mixture are combined in a polymerization reaction vessel. It may be added after stirring and mixing.

The method of emulsifying and dispersing the oily mixture in an aqueous dispersion medium with a predetermined particle size is not particularly limited. For example, a method of stirring with a homomixer (for example, manufactured by Tokushu Kika Kogyo Co., Ltd.) or the like, a line mixer, an element type Examples thereof include a method of passing through a static dispersion device such as a static dispersion device.
The aqueous dispersion medium and the oily mixed liquid may be separately supplied to the static dispersion apparatus, or a dispersion liquid that has been mixed and stirred in advance may be supplied.

In the method for producing expanded particles according to the present invention, a step of copolymerizing the monomer mixture is then performed. The method for copolymerization is not particularly limited, and examples thereof include a method for copolymerizing the monomer mixture by heating.
The particles encapsulating the volatile swelling agent as the core agent in the thus obtained copolymer shell are then subjected to a surface treatment with a curing agent capable of reacting with epoxy groups on the surface of the shell of the particles. You may pass through the process of dehydration, the process of drying, etc. before performing.

In the method for producing expanded particles according to the present invention, the surface of the shell of the expanded particles is then subjected to a surface treatment with a curing agent capable of reacting with an epoxy group, if necessary.
The method of surface-treating with the curing agent capable of reacting with the epoxy group is not particularly limited, and for example, as described above, the surface can be treated by a general heating and stirring method.

The foamable composition of the present invention contains a curing agent capable of reacting with an epoxy group.
The curing agent capable of reacting with the epoxy group is not particularly limited, and examples thereof include amine compounds, acid anhydrides, novolak curing agents, and the like.
The amine compound is not particularly limited, and examples thereof include aliphatic amines, alicyclic amines, aromatic amines, and modified products thereof.
The aliphatic amine is not particularly limited, and examples thereof include ethylenediamine and its adduct, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, hexamethylenediamine. And modified products thereof, N-aminoethylpiperazine, bis-aminopropylpiperazine, trimethylhexamethylenediamine, bis-hexamethylenetriamine, dicyandiamide, diacetacrylamide, various modified aliphatic polyamines, polyoxypropylenediamine, and the like.

The alicyclic amine is not particularly limited. For example, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane, 3-amino-1-cyclohexylaminopropane, 4,4′-diaminodicyclohexylmethane, isophoronediamine. 1,3-bis (aminomethyl) cyclohexane, N-dimethylcyclohexylamine and the like.

The aromatic amine is not particularly limited. For example, 4,4′-diaminodiphenylmethane (methylenedianiline), 4,4′-diaminodiphenyl ether, diaminodiphenylsulfone, m-phenylenediamine, 2,4′-toluylenediamine , M-toluylenediamine, o-toluylenediamine, metaxylylenediamine, xylylenediamine and the like.

In addition, as the amine compound, tertiary amines, imidazoles, hydrazides, amidoamines, ketimines, polyamide amines such as amino polyamide resins, amino group-containing prepolymers such as amino adducts of epoxy resins, and other special amine modified products May be used.
The tertiary amines are not particularly limited. For example, dimethylaminomethylphenol, 2,4,6-tri (dimethylaminomethyl) phenol, tri-2ethylhexane salt of tri (dimethylaminomethyl) phenol, and these And the like.

The imidazoles are not particularly limited. For example, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole. 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2undecylimidazole, 1-cyanoethyl-2-isopropylimidazole, 1-cyanoethyl 2-phenylimidazole, 1-cyanoethyl-2-methylimidazole trimellitate, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate 2,4-diamino-6- [2'-methylimidazolyl- (1) ']-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1)']- Ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1) ′]-ethyl-s-triazine, 1-dodecyl-2-methyl-3-benzylimidazo Rium chloride, 1,3-dibenzyl-2-methylimidazolium chloride, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-cyanoethyl-2-phenyl- 4,5-di (cyanoethoxymethyl) imidazole, composite of 2-methylimidazole and triazine, 2-phenylimidazole and triazine Composite products of the gin and the like.

The hydrazides are not particularly limited, and examples thereof include isophthalic acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide.

The acid anhydride is not particularly limited. For example, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic acid, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride, trialkyl Tetrahydrophthalic anhydride, methylcyclohexenetetracarboxylic dianhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, ethylene glycol bisanhydrotrimellitate, glycerin bis (anhydro) Trimellitate) monoacetate, dodecenyl succinic anhydride, aliphatic dibasic acid polyanhydride, chlorendic anhydride and the like.

The novolak curing agent is not particularly limited, and examples thereof include phenol novolak, xylylene novolak, bis A novolak, triphenylmethane novolak, biphenyl novolak, dicyclopentadienephenol novolak, and terpene phenol novolak.

The use of the foamable composition of the present invention is not particularly limited, and for example, by blending with a matrix resin and molding using a molding method such as injection molding or extrusion molding, heat insulation, heat insulation, sound insulation, sound absorption It can be used to produce a foamed molded article having properties, vibration proofing, weight reduction and the like. Since the foamable composition of the present invention is less likely to cause particle rupture and shrinkage even when heated at high temperatures, the foamable composition of the present invention can be used even when a high temperature molding step is required during production. Using the product, foam molding can be performed at a high expansion ratio.

A method for producing a foamed molded article comprising a step of producing a foamable resin composition containing the foamable composition of the present invention and a matrix resin, and a step of molding the foamable resin composition, It is one of the present inventions.

The matrix resin is not particularly limited, and examples thereof include general thermoplastic resins such as polyvinyl chloride, polystyrene, polypropylene, polypropylene oxide, and polyethylene, engineering plastics such as polybutylene terephthalate, nylon, polycarbonate, and polyethylene terephthalate, and ethylene. And thermoplastic elastomers such as vinyl chloride, vinyl chloride, olefin, urethane, and ester. These may be used independently and 2 or more types may be used together.

The method for molding the foam molding resin composition is not particularly limited, and examples thereof include kneading molding, calendar molding, extrusion molding, and injection molding. In the case of injection molding, the construction method is not particularly limited, and a short shot method in which a part of the foam molding resin composition is put in a mold and foamed, or after the mold is fully filled with the foam molding resin composition. The core back method etc. which open to the place which wants to make a mold foam are mentioned.

The use of the foam molded article obtained by using the method for producing a foam molded article of the present invention is not particularly limited. For example, automobile interior materials such as door trims and instrument panels (instrument panels), automobile exterior materials such as bumpers, Application of building materials such as wood powder plastic, shoe soles, artificial cork and the like.

ADVANTAGE OF THE INVENTION According to this invention, even if it heats at high temperature, the bursting and shrinkage | contraction of particle | grains are hard to produce, and the foamable composition which can be used for foam molding by a high foaming ratio can be provided. Moreover, according to this invention, the manufacturing method of the foaming molding using the said foamable composition can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1, Comparative Example 1)
In a polymerization reaction vessel, 8 L of water, 10 parts by weight of colloidal silica (manufactured by Asahi Denka) as dispersion stabilizer, 0.3 part by weight of polyvinylpyrrolidone (manufactured by BASF) as auxiliary stabilizer, 0.7 weight of 1N hydrochloric acid The aqueous dispersion medium was prepared. Next, an oily mixture was prepared with the formulation shown in Table 1, and this oily mixture was added to the aqueous dispersion medium to prepare a dispersion.
The obtained dispersion was stirred and mixed with a homogenizer, then charged into a pressure polymerizer (20 L) purged with nitrogen, and reacted at 60 ° C. for 20 hours while being pressurized (0.2 MPa).

About the obtained reaction product, as a curing agent capable of reacting with an epoxy group with respect to the theoretical curing agent amount with respect to the epoxy equivalent of an epoxy group-containing monomer having at least one polymerizable unsaturated bond in the oily mixture used. Surface treatment was performed with a curing agent capable of reacting with an epoxy group by reacting at a temperature of 50 ° C. for 12 hours using a 1-fold amount of isophoronediamine. The obtained reaction product was repeatedly filtered and washed with water, and then dried to obtain expanded particles surface-treated with a curing agent capable of reacting with an epoxy group.

(Evaluation)
The following evaluation was performed about the expanded particle obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Evaluation of expansion ratio About 0.1 g of expanded particles was weighed and placed in a 10 mL measuring cylinder. This graduated cylinder was put into an oven heated to 160 ° C, 180 ° C, 200 ° C or 220 ° C for 5 minutes, and the volume of the expanded particles in the graduated cylinder was measured.
When the volume of the expanded particles in the graduated cylinder is less than 2 mL, “X”, when the volume is 2 mL or more and less than 5 mL, “△”, and when the volume is 5 mL or more and less than 8 mL, “◯” The case of 8 mL or more was evaluated as “と し て”.

(2) Evaluation of heat resistance The sample after the measurement of (1) was put into an oven heated to 220 ° C. for 10 minutes, and the volume of the expanded particles in the graduated cylinder was measured.
When the volume in the graduated cylinder of the expanded particles immediately after the measurement of (1) is performed is L, and the volume in the graduated cylinder of the expanded particles after treatment at 220 ° C. for 10 minutes is H, The case where H / L is less than 0.4 is “x”, the case where it is 0.4 or more and less than 0.6 is “Δ”, and the case where it is 0.6 or more and less than 0.8 is “ The case where it was 0.8 or more was evaluated as “と し て”.

ADVANTAGE OF THE INVENTION According to this invention, even if it heats at high temperature, the bursting and shrinkage | contraction of particle | grains are hard to produce, and the foamable composition which can be used for foam molding by a high foaming ratio can be provided. Moreover, according to this invention, the manufacturing method of the foaming molding using the said foamable composition can be provided.

Claims (4)

A foamable composition comprising foamed particles and a curing agent capable of reacting with an epoxy group,
The foamed particles contain a volatile swelling agent as a core agent in a shell made of a copolymer,
The copolymer is obtained by copolymerizing a monomer mixture containing a nitrile monomer and an epoxy group-containing monomer having at least one polymerizable unsaturated bond ,
A foamable composition comprising 1 to 30 parts by weight of an epoxy group-containing monomer having at least one polymerizable unsaturated bond based on 100 parts by weight of the nitrile monomer . The foamable composition according to claim 1, wherein the epoxy group-containing monomer having at least one polymerizable unsaturated bond is glycidyl methacrylate. The foaming composition according to claim 1 or 2, wherein the curing agent capable of reacting with an epoxy group is an amine compound. Producing a foam molding resin composition comprising the foamable composition according to claim 1, 2 or 3, and a matrix resin;
And a step of molding the foam molding resin composition.