JPH05311024A - Foamable acrylate composition - Google Patents

Abstract

PURPOSE:To provide a foamable compsn. which gives a foam excellent in compression recovery, strengths, water resistance, weatherability, etc. CONSTITUTION:The compsn. comprises 100 pts.wt. (solid base) emulsion of an acrylilic ester copolymer obtd. by copolymerizing 10-99.9wt.% acrylic ester, 0.1-10wt.% monomer with cross-linking groups, and 0-89.9wt.% other monomer and 0-20 pts.wt. wax.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an acrylic foam composition and an acrylic foam obtained from the composition.

[0002]

2. Description of the Related Art Conventionally, foam has been widely used as a bonding material for metals, plastics, wood, plywood, carpets, etc., building materials, interior materials, heat insulating materials, soundproofing materials, vibration damping materials, protective materials for home appliances, etc. As the material, various materials such as rubber, polyolefin, polystyrene, polyvinyl chloride, acrylic resin, polyurethane and thermosetting resin are used. These foams are generally foamed using blowing agents, and are also especially natural rubber latex,
For chloroprene latex, styrene-butadiene rubber latex, nitrile rubber latex, acrylic polymer emulsion, etc., a cross-linking agent, antioxidant, thickener, foam stabilizer, dispersant, gelling agent, filler, foaming aid, etc. A foam is formed by mixing and mechanically foaming and then heating and drying. However, the use of a foaming agent such as a volatile solvent or a Freon-based gas poses a problem in terms of environment, health, etc., and in terms of performance, foam strength, weather resistance, etc. were not sufficient. In the case of mechanically foaming the latex or emulsion as described above, a gelling agent is used, so that the balance between the stability of the foam composition and the pot life becomes poor, and further natural rubber, chloroprene latex, styrene are used. In the case of rubber latex such as butadiene rubber latex and nitrile rubber latex, weather resistance and water resistance were not sufficient. On the other hand, a foam obtained by mechanically foaming an acrylic polymer emulsion, gelling it, and heating and drying it (JP-A-63-8).
9585, JP-A-2-264079, etc.)
Has a good balance in general performance, but has practical problems such as poor compression recovery of the foam due to lack of elasticity.

[0003]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to overcome the conventional drawbacks of acrylic foams, and to form a foam excellent in compression recovery, strength, water resistance and weather resistance. A foam composition and an acrylic foam obtained from the composition.

[0004]

The present invention includes (1) and (a).
Acrylic acid ester monomer unit and / or methacrylic acid ester monomer unit 10 to 99.9% by weight, (b)
100 parts by weight of an emulsion of an acrylic copolymer consisting of 0.1 to 10% by weight of a monomer unit having a crosslinkable functional group and (c) 0 to 89.9% by weight of another monomer unit (solid content conversion). ), And (2) 0 to 20 parts by weight of a wax, and an acrylic foam obtained by foaming and cross-linking the acrylic foam composition. ..

The present invention will be described in detail below, which will clarify the purpose, constitution and effect of the present invention. (1) An acrylic copolymer emulsion used in the acrylic foam composition of the present invention,
(A) Acrylic ester monomer unit or methacrylic acid ester monomer unit, which is the main constituent unit of the acrylic copolymer (hereinafter, the acrylic acid ester monomer and the methacrylic acid ester monomer are collectively referred to In this case, the "acrylic ester monomer") is composed of an ester of acrylic acid or methacrylic acid and an aliphatic, alicyclic or aromatic unsubstituted alcohol. The term "unsubstituted" as used herein means having no groups other than hydrocarbon groups. Specific examples of such acrylic ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, isobutyl acrylate, and n methacrylate.
-Butyl, isobutyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate. , N-nonyl acrylate, isononyl acrylate, n-nonyl methacrylate, isononyl methacrylate, decyl acrylate, decyl methacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, n-amyl acrylate , Isoamyl acrylate, n-amyl methacrylate,
Examples thereof include isoamyl methacrylate, lauryl acrylate, lauryl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate. Preferred acrylic ester monomers are alkyl acrylates or methacrylic acid alkyl esters in which the alkyl group has 1 to 12 carbon atoms, more preferably ethyl acrylate, n-butyl acrylate or isononyl acrylate. Especially preferred is ethyl acrylate. These acrylic ester monomers can be used alone or in admixture of two or more.

The content of the acrylic ester monomer unit (a) in the acrylic copolymer in the present invention is 10 to 10.
It is 99.9% by weight, preferably 15 to 98.0% by weight, more preferably 17 to 97% by weight. (I)
When the content of the acrylic ester monomer unit is less than 10% by weight, the weather resistance becomes insufficient especially when it is used as an automobile molding, a soundproofing material for construction and the like. On the other hand, when it exceeds 99.9% by weight, the strength and water resistance of the foam are deteriorated, which is not preferable.

Next, the crosslinkable functional group in the monomer unit (b) which constitutes the acrylic copolymer in the present invention is used in the presence or absence of a catalyst after foaming the foam composition of the present invention. In the presence, under heating or under non-heating, is not particularly limited as long as it is a functional group capable of crosslinking the acrylic copolymer, as a specific example, a carboxyl group,
Examples thereof include an acid anhydride group, a hydroxyl group, an amino group, an amide group and an epoxy group.

In the present invention, the (b) monomer unit having a crosslinkable functional group in the acrylic copolymer is _{(i) the} monomer directly, and (i) and (c) each unit. And _{(ii) a} precursor monomer capable of forming a unit (b) is copolymerized with a monomer corresponding to each unit (a) and (c), It can be formed by a method of introducing a crosslinkable functional group into the unit composed of the precursor monomer in the copolymer, but the method _{(i )} is preferable. Therefore, the following description will be given mainly from the viewpoint of producing an acrylic copolymer using a monomer having a crosslinkable functional group.

Specific examples of the monomer having a crosslinkable functional group are as follows:
Acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid and other ethylenically unsaturated monocarboxylic acids or polycarboxylic acids or salts thereof; as the monomer having an acid anhydride group, fumaric acid, Acid anhydrides of ethylenically unsaturated polycarboxylic acids such as maleic acid; monomers having a hydroxyl group include allyl alcohol, methallyl alcohol, hydroxymethyl acrylate, hydroxymethyl methacrylate, 1-hydroxyethyl acrylate, methacrylic acid. Acid 1-hydroxyethyl, acrylic acid 2
-Hydroxyethyl, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, etc .; Examples of the monomer having an amino group include aminoethyl acrylate and aminomethacrylate. Ethyl, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, β-aminoethyl vinyl ether, dimethylaminoethyl vinyl ether, vinylamine, vinylmethylamine, vinyldimethylamine, allylamine, allyldimethylamine, methallyldiethylamine, etc .; having amide groups Examples of the monomer include acrylamide, methacrylamide, ethacrylamide, diacetone acrylamide, diacetone methacrylamide, crotonamide, and Amides of ethylenically unsaturated carboxylic acids such as condiamide, methylitaconamide, maleindiamide; as monomers having an epoxy group, ethylenically unsaturated such as glycidyl acrylate, glycidyl methacrylate, vinyl glycidyl ether, allyl glycidyl ether Examples thereof include glycidyl ester of carboxylic acid and glycidyl ether of ethylenically unsaturated alcohol.

Further, (b) the monomer unit having a crosslinkable functional group may have two or more kinds of the above-mentioned crosslinkable functional groups. In this case, there are various combinations of crosslinkable functional groups. For example, for monomers having both a carboxyl group and a hydroxyl group, mono (hydroxyethyl) itaconate, mono (hydroxyethyl) maleate, etc. However, for monomers having both a carboxyl group and an amino group, itaconic acid mono (aminoethyl) acid, maleic acid mono (aminoethyl), etc. are available as monomers having both a carboxyl group and an amide group. Itaconic acid monoamide, maleic acid monoamide, etc., Monoglycidyl itaconic acid, monoglycidyl maleate, etc., are monomers having both a carboxyl group and an epoxy group, monomers having both a hydroxyl group and an amino group. 1-amino-2-hydroxyethyl acrylate, 1-hydroxy-2-aminoethyl methacrylate, itaconic acid (aminoethyl ) (Hydroxyethyl), maleic acid (aminoethyl) (hydroxyethyl) and the like, and monomers having both a hydroxyl group and an amide group include N-methylol acrylamide, N-methylol methacrylamide and the like, and hydroxyl group and an epoxy group. Itaconic acid (hydroxyethyl) (glycidyl), maleic acid (hydroxyethyl) (glycidyl), and the like are included in the monomer having both and, and N-amino is included in the monomer having both an amino group and an amide group. Ethyl acrylamide, N-aminoethyl-methacrylamide, N-dimethylaminomethyl-acrylamide, N-dimethylaminomethyl-methacrylamide, N-aminopropyl-acrylamide, N-aminopropyl-methacrylamide, N-dimethylaminopropyl-acrylamide , N-dimethylaminopropy - methacrylamide, monomers in body itaconic acid having both an amino group and an epoxy group (aminoethyl)
(Glycidyl), maleic acid (aminoethyl) (glycidyl), and the like. Further, examples of the monomer having both an amide group and an epoxy group include glycidyl itaconic acid monoamide and glycidyl maleic acid monoamide.

As the monomer having a crosslinkable functional group in the present invention, a monomer having a single crosslinkable functional group can be used when the functional group itself can cause a crosslinking reaction. However, usually, a monomer having two or more kinds of functional groups capable of reacting with each other in the molecule is used, or two or more kinds of monomers each having a functional group capable of reacting with each other are used in combination. Preferably. Examples of such a combination of functional groups capable of reacting with each other include a combination of a carboxyl group / a hydroxyl group (the same applies hereinafter), a carboxyl group / amino group, a carboxyl group / epoxy group, an acid anhydride group / hydroxyl group, an acid anhydride group. / Amino group, hydroxyl group / epoxy group, amino group / epoxy group and the like. In any of these cases, the monomers having a crosslinkable functional group can be used alone or in combination of two or more.

The content of the monomer unit (b) having a crosslinkable functional group in the acrylic copolymer in the present invention is
It is 0.1 to 10% by weight. A preferable content rate is 0.5 to
It is 7% by weight, more preferably 1 to 5% by weight. (B) When the content of the monomer unit having a crosslinkable functional group is less than 0.1% by weight, the strength and water resistance of the foam are reduced, and when it exceeds 10% by weight, the polymerization stability is generally low. In addition, the storage stability of the acrylic copolymer emulsion is impaired.

Further, (c) the other monomer unit that can constitute the acrylic copolymer in the present invention is a monomer that can be copolymerized with the monomer that provides each of the units (a) and (b). It consists of a quantity. Such other monomers include aromatic vinyl-based monomers, vinyl cyanide-based monomers, ethylenically unsaturated sulfonic acid ester monomers, ethylenically unsaturated alcohol ester monomers, ethylene One or more of unsaturated unsaturated ether monomers, ethylenically unsaturated silane monomers, vinyl halide monomers, and aliphatic conjugated diene monomers are used.

Examples of the aromatic vinyl monomers are styrene, α-methylstyrene, o-methylstyrene, p-
Methylstyrene, o-ethylstyrene, p-ethylstyrene, α-chlorostyrene, p-chlorostyrene, p-
Methoxystyrene, p-aminostyrene, p-acetoxystyrene, sodium styrenesulfonate, α-vinylnaphthalene, sodium 1-vinylnaphthalene-4-sulfonate, 2-vinylfluorene, 2-vinylpyridine, 4-vinylpyridine, etc. Yes, styrene is particularly preferred.

Examples of the vinyl cyanide-based monomer include acrylonitrile, α-chloroacrylonitrile, α-methoxyacrylonitrile, methacrylonitrile, α-chloromethacrylonitrile, α-methoxymethacrylonitrile, vinylidene cyanide and the like. And acrylonitrile is particularly preferable.

Examples of the ethylenically unsaturated sulfonic acid ester monomer include alkyl vinyl sulfonate and alkyl isoprene sulfonate.

Examples of the ethylenically unsaturated alcohol ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, allyl acetate, methallyl caproate, allyl laurate, allyl benzoate, alkyl. Examples thereof include vinyl sulfonate, allyl alkyl sulfonate, and vinyl aryl sulfonate.

Examples of the ethylenically unsaturated ether monomer include methyl vinyl ether, ethyl vinyl ether,
Examples include n-propyl vinyl ether, isopropyl vinyl ether, methyl allyl ether and ethyl allyl ether.

Examples of the ethylenically unsaturated silane include vinyltriethylsilane, methylvinyldichlorosilane,
Examples include dimethylallylchlorosilane and vinyltrichlorosilane.

Examples of the vinyl halide monomer include:
There are vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl bromide, vinylidene bromide, 1,2-dibromoethylene and the like.

Examples of the aliphatic conjugated diene-based monomer include
1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-neopentyl-1,3-butadiene, 2-chloro-1,3-
Butadiene, 1,2-dichloro-1,3-butadiene,
2,3-dichloro-1,3-butadiene, 2-bromo-
There are 1,3-butadiene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadienes, linear and side chain conjugated hexadienes, etc., and 1,3-butadiene is particularly preferable.

The other preferable monomers in the present invention are aromatic vinyl type monomers and vinyl cyanide type monomers.

The content of the other monomer unit (c) in the acrylic copolymer in the present invention is 0 to 89.9% by weight, preferably 5 to 84.5% by weight, more preferably 10%. ~ 81 wt%. (C) When the content of the other monomer units exceeds 89.9% by weight, the weather resistance of the acrylic foam decreases.

A preferred combination of the monomers constituting units (a) to (c) of the acrylic ester copolymer in the present invention is ethyl acrylate / methyl methacrylate / methacrylic acid / N-methylol acrylamide. Combination (same below), (meth) acrylic acid ester /
(Meth) acrylic acid / amide group-containing monomer, (meth) acrylic acid ester / (meth) acrylic acid / amide group-containing monomer / aromatic vinyl-based monomer / vinyl cyanide-based monomer, ( Examples thereof include (meth) acrylic acid ester / (meth) acrylic acid / amide group-containing monomer / vinyl cyanide-based monomer, and a more preferable combination is ethyl acrylate / methacrylic acid / N-methylol acrylamide / Examples include styrene / acrylonitrile, n-butyl acrylate / methyl methacrylate / methacrylic acid / N-methylol acrylamide / acrylonitrile.

The emulsion of the acrylic copolymer (1) in the present invention is preferably produced by emulsion-polymerizing the monomers corresponding to the units (a) to (c). Such emulsion polymerization is usually carried out with a total of 100 monomers.
100 to 200 parts by weight of water is used with respect to parts by weight, and in the presence of an emulsifier and a polymerization initiator, optionally a chain transfer agent, various electrolytes, a pH adjusting agent, etc. are added to give 10 to 90 parts by weight.
It is carried out by polymerizing at a temperature of ° C, preferably 40 to 80 ° C for 5 to 15 hours. In emulsion polymerization, the monomers to be used can be added by an appropriate method such as batch addition, divided addition or continuous addition. In the divided addition or continuous addition, the monomer can be added together with other addition components such as a polymerization initiator, or
It is also possible to add all the above-mentioned other additive components in advance and add only the monomer in divided or continuous manners. Further, the monomers to be added in portions or continuously can be emulsified in advance.

As the emulsifier in the emulsion polymerization, one or more kinds of anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. are used. These surfactants have a lipophilic group of fluorine. It is also possible to use a modified fluorosurfactant. Examples of the anionic surfactant include alkali metal salts of fatty acids, sulfuric acid ester salts of higher alcohols, polyoxyethylene / alkyl ether sulfates, polyoxyethylene / alkylphenyl ether sulfates, fatty acid sulfuric acid ester salts, and aliphatic amines. Or aliphatic amide sulfate, dibasic fatty acid ester sulfonate, aliphatic amide sulfonate, alkyl or alkenyl sulfonate, alkylaryl sulfonate, alkyl sulfosuccinate, formalin-condensed naphthalene sulfonate A salt, a phosphate ester salt of an aliphatic alcohol, a polyoxyethylene alkyl (phenyl) ether phosphate ester salt, or the like is used. Specific examples of the anionic surfactant include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium diphenyl ether disulfonate, sodium succinate dialkyl ester sulfonate, and the like, and particularly sodium lauryl sulfate and sodium diphenyl ether disulfonate should be used. Thereby, the effect of the present invention is remarkably exhibited.

As the nonionic surfactant, polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, etc. are used. ..

Further, the fluorine-based surfactant that can be used in the emulsion polymerization has basically the same chemical structure as that of an ordinary surfactant, and examples thereof include a carboxyl group as a hydrophilic group. Salts, sulfates, sulfonates, phosphates and other groups of anionic surfactants, hydrophilic groups of polyoxyethylene groups of nonionic surfactants, hydrophilic groups of amine salts, quaternary ammonium salts There are cationic surfactants and amphoteric surfactants having groups such as. Fluorosurfactants generally have high surface activity, and many of them exhibit a sufficient emulsifying action even if the lipophilic group has a smaller number of carbon atoms than general surfactants. Examples of such fluorine-based surfactants include perfluoroalkylcarboxylic acid salts, perfluoroalkylsulfonic acid salts, perfluoroalkylphosphoric acid esters, perfluoroalkyltrimethylammonium salts, perfluoroalkylpolyoxyethylenes, perfluoroalkylbetaines. Etc.

The preferable amount of the emulsifier used is usually 0.5 to 10% by weight, particularly 1 to 10% by weight, based on the total amount of the monomers.
8% by weight is preferred. If the amount of the emulsifier used is too small, the stability of the emulsion tends to decrease such as coagulation, and if it is too large, the water resistance of the acrylic foam formed from the emulsion tends to decrease.

As the polymerization initiator which can be used in the emulsion polymerization, inorganic initiators such as potassium persulfate, ammonium persulfate and hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, paramenthane hydroper Organic compounds such as oxide, benzoyl peroxide, di-t-butyl peroxide, dilauroyl peroxide, azobisisobutyronitrile, asobisisovaleronitrile, azobisisocapronitrile, azobis (phenylisobutyronitrile) A system initiator can be mentioned. The amount of the polymerization initiator used is preferably 0.03 to 2% by weight, more preferably 0.05 to 1% by weight, based on the total amount of the monomers.

Further, a reducing agent, a chelating agent or the like may be added to accelerate emulsion polymerization. Examples of the reducing agent, sodium pyrobisulfite, sodium sulfite, sodium bisulfite, ferrous sulfate, glucose,
Formaldehyde sodium sulfoxylate, L-ascorbic acid and salts thereof, sodium bisulfite and the like can be mentioned, and examples of the chelating agent include glycine, alanine, sodium ethylenediaminetetraacetate and the like.

As the chain transfer agent which can be used in the emulsion polymerization, α-methylstyrene dimer, terpinolene, α containing 2,4-diphenyl-4-methyl-1-pentene component preferably in an amount of 60% by weight or more.
-Terpinene, γ-terpinene, dipentene, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, dimethylxanthogen disulfide, diethylxanthogen disulfide, diisopropylxanthogen disulfide, tetremethylthiuram disulfide, tetraethylthiuram disulfide, Examples thereof include tetrabutyl thiuram disulfide and dipentamethyl thiuram disulfide. The amount of the chain transfer agent used is usually 15% by weight or less based on the total amount of the monomers.

The emulsion polymerization method for producing the emulsion of (1) acrylic copolymer in the present invention has been described above. The emulsion of (1) acrylic copolymer is emulsified at least at the final stage of the polymerization. It can also be produced by a method other than the polymerization method, for example, a method of emulsifying and dispersing an acrylic copolymer obtained by bulk polymerization, solution polymerization, precipitation polymerization, suspension polymerization, bulk-suspension polymerization, etc. in an aqueous medium. Can be done. Examples of the emulsifier used in this case include various surfactants used in the emulsion polymerization method described above.

Further, the monomer unit having a (b) crosslinkable functional group in the present invention is prepared by introducing the crosslinkable functional group into a unit composed of its precursor monomer by the method _(ii) . When forming, the acrylic copolymer containing the precursor monomer units is substantially emulsion, solution, finely suspended in a suitable medium, swollen with a suitable solvent, etc. It is preferable to use it in a form that can be carried out uniformly. After the reaction, if necessary, the generated acrylic copolymer is emulsified and dispersed in an aqueous medium.

The glass transition point of the acrylic copolymer in the present invention is usually -50 ° C to + 25 ° C, preferably -30 ° C to + 15 ° C. When the glass transition point is lower than -50 ° C, the foam tends to have too strong tackiness to be difficult to handle, and tends to have low strength. Meanwhile +
If the temperature is higher than 25 ° C, the foam becomes too hard and poor in flexibility, so that when it is used as a bonding material, for example, the shear strength tends to be insufficient.

The glass transition point of the acrylic copolymer in the present invention is determined by the differential scanning calorimeter (DS) manufactured by Rigaku Denki.
C) was used and measured under the following conditions. About 5 g of the acrylic copolymer emulsion is thinly spread on a glass plate and dried at 25 ° C. for 7 days to form a film. About the obtained film, temperature rising rate: 20 ° C /
The glass transition point is measured under measurement conditions of minutes, atmosphere: nitrogen, and sample amount: 20 mg.

Further, the average particle size of the emulsion of the acrylic copolymer (1) in the present invention is usually 120-5.
00 nm, preferably 170-350 nm. If the average particle size is less than 120 nm, the viscosity of the emulsion becomes too high, making it difficult to obtain a high solid content emulsion, and as a result, it becomes difficult to obtain a good film. On the other hand, when it exceeds 500 nm, the water resistance and solvent resistance of the foam tend to be low. The average particle size is a number average of particle sizes of 100 or more emulsion particles from an electron micrograph of an emulsion treated with uranyl acetate and osmic acid. The average particle size of the acrylic copolymer emulsion can be controlled by adjusting stirring conditions such as emulsion polymerization and the amount of the emulsifier used.

The wax (2) used in the acrylic foam composition of the present invention has a function of imparting a releasing effect to the individual foams of the foam and improving the compression recovery of the resulting acrylic foam. Have. Specific examples of such waxes include oxidized polyethylene wax, oxidized polypropylene wax, glycol-modified oxidized polypropylene wax, ethylene acrylic acid copolymer wax, and paraffin wax. A preferred wax is oxidized polyethylene wax.

These waxes (2) may be added by emulsifying them in advance in order to improve the miscibility of the acrylic copolymer (1) with the emulsion.

The compounding amount of the wax (2) in the present invention is 0 to 20 parts by weight, preferably 0.2 to 20 parts, per 100 parts by weight (in terms of solid content) of the emulsion of the acrylic copolymer (1). Parts by weight. When the amount of the wax added is more than 20 parts by weight, the strength, water resistance, weather resistance and the like of the foam deteriorate.

In order to improve various properties, the acrylic foam composition of the present invention contains, if necessary, a flame retardant, a crosslinking agent, a filler, a dye / pigment, a gelling agent, a foaming agent, a foam stabilizer, A compounding agent such as a thickener and an aromatic may be further added.

Examples of the flame retardant include phosphoric acid ester type, halogen-containing phosphoric acid ester type, ammonium polyphosphate, antimony trioxide, zinc borate, barium metaborate, aluminum hydroxide, magnesium hydroxide and the like.

Examples of the cross-linking agent include phenol resin, urea resin, amino resin, aniline resin, melamine resin, epoxy resin, azo compound, isocyanate compound and zinc. The strength of the acrylic foam can be further improved by using these crosslinking agents.

Examples of the filler include calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, barium hydroxide, basic zinc carbonate, basic lead carbonate, ferric hydroxide, silica sand and clay. Be done.

Examples of the dyes and pigments include inorganic pigments such as titanium white, aniline black and phthalocyanine blue,
Organic pigments or dyes may be mentioned.

Examples of the gelling agent include ammonium salts such as ammonium acetate, ammonium chloride and ammonium carbonate, alkylphenol alkylene oxide adducts, polyvinyl methyl ether, polypropylene glycol, polyether polyformal, methyl cellulose, hydroxyethyl cellulose, and silicone-based heat-sensitive materials. Agents and the like can be mentioned.

Examples of the foaming agent include sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium polyoxyethylene alkylphenol ether sulfate and the like.

Examples of the foam stabilizers include ammonium stearate and alkylsulsuccinate.

Examples of the thickener include sodium polyacrylate, polyvinyl alcohol, sodium alginate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, casein, starch and the like.

Examples of the fragrance include acetophenone, vanillin, coumarin, citral, organic carboxylic acid, methyl salicylate, geranyl acetate, geraniol,
Eugenol, terpineol, linalool, lavender oil and the like can be mentioned.

The amount of these compounding agents used is usually 2 to 50 parts by weight of the flame retardant and 0.1% by weight of the crosslinking agent to 100 parts by weight (in terms of solid content) of the emulsion of the acrylic copolymer (1). 1 to 10 parts by weight, fillers 2 to 200 parts by weight, dyes and pigments 0.1 to 10 parts by weight, gelling agents 0.05 to 5 parts by weight, foaming agents 0.1 to 10 parts by weight, Foaming agent is 0.1
About 10 parts by weight, about 0.05 to 10 parts by weight of the thickener and about 0.5 to 10 parts by weight of the fragrance.

Further, in the acrylic foam composition of the present invention, a rubber latex such as natural rubber latex, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, chloroprene rubber latex, polyurethane emulsion, poly, etc., as long as the characteristics thereof are not impaired. It is also possible to mix a resin emulsion such as a vinyl chloride emulsion or a polystyrene emulsion, which may further improve various properties of the acrylic foam of the present invention.

In the acrylic foam composition of the present invention, the total solid content is 55 to 85% by weight, and the viscosity of the uncrosslinked foam when double-foamed by volume is 2,000 to 70,000 cps ( However, a BM type viscometer, a rotor No. 4 and a rotation speed of 6 rpm were used for the measurement), it is possible to form a foam having various properties such as compression recovery, water resistance and weather resistance. it can.

For forming a foam using the acrylic foam composition of the present invention, a gas (preferably air or the like) is introduced and mechanically stirred by an Oaks mixer, a whipper or the like to form a continuous or discontinuous material. Can be carried out. The expansion ratio varies depending on the use and characteristics of the foam, but is usually 1.5 to 10 times, preferably 2 to 7 times. The bulk specific gravity of a foam formed from the acrylic foam composition of the present invention is usually 0.0 immediately after foaming.
It is in the range of 8 to 0.9.

A foam formed by using the acrylic foam composition of the present invention is applied to a base material if necessary, and then 80 ° C. or higher, preferably 120 to 170 ° C.
It is heated and dried at a temperature of C, usually for 10 minutes or longer, preferably for 15 to 40 minutes. The shape, thickness, size and the like of the foam are appropriately selected according to the purpose of use, and in some cases, it is possible to repeatedly apply to form a thick foam body. Further, the formed foam can be subjected to various secondary processing such as surface treatment such as embossing and printing, and mechanical processing such as cutting and cutting.

The foam formed from the acrylic foam composition of the present invention has a beautiful skin based on a uniform foam structure, is soft and can achieve a sufficient cosmetic effect, and has a good appearance. Is excellent in Moreover, in addition to compression recovery, elasticity, strength, water resistance and weather resistance, it has excellent properties such as solvent resistance and air permeability. Therefore,
Structural materials, surface materials, intermediate layer materials, etc., such as building materials, interior materials (for floors, ceilings, walls, etc.), damping materials (for automobiles, audio, etc.), heat insulation / heat insulation materials (for automobiles, Audio, home appliances, construction, etc., soundproofing materials (automobiles, audios, etc.), protective materials (automobiles, aircraft, audio, home appliances, OA equipment, etc.), cushion materials (carpets, baths) Mats), automobile moldings, joining materials (wood plywood, inorganic boards, wood, metals, plastics, etc.). Furthermore, a foam formed using the acrylic foam composition of the present invention can be used as an adhesive foam sheet, an adhesive foam tape or the like by applying an adhesive to the surface thereof.

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Here, parts are by weight.

EXAMPLES _(I) Production of Copolymer Emulsions A to F In a reaction vessel, 200 parts of distilled water, 0.8 parts of potassium carbonate, 0.03 part of sodium acid sulfite, and 0.3 parts of potassium persulfate are placed.
Part and the monomer and emulsifier shown in Table 1 were charged, and the mixture was heated to 70 °
Polymerization was carried out at C for 5 hours to prepare copolymer emulsions A to F shown in Table 1. The polymerization conversion rates reached 98% or more in all cases.

_(II) Preparation of Foam Composition Copolymer emulsions A to F shown in Table 1 (100 parts each) (solid content conversion), oxidized polyethylene wax (the amount used is shown in Table 2).
Shown in. ) And the following compounding agents (the amount used is 100 parts of the copolymer emulsion (solid content equivalent)) were thoroughly mixed to prepare a foam composition. Compounding agent Ammonium stearate (foam stabilizer) 2 parts Melamine resin (crosslinking agent) 2 parts Sodium polyacrylate (thickener) 1 part

[0059]_(III)Formation of Foam Air is added to the foam composition prepared as described above.
Put it in, stir foam using a whipper, and
After applying it to the base material, it is heated at 135 ° C for 30 minutes,
Dried to a density of 0.30 g / cm3 , 2mm thick fo
Formed a membrane sheet.

[0060]_(IV)Foam characteristic evaluation Regarding the foam formed as described above, the following
Each property was evaluated according to the standard. The evaluation results are shown in Table 2.Compression recovery 4kg / cm2 for foam sheet Pressure of 10
After applying pressure for 10 minutes and releasing the pressure 10 seconds after the original thickness
The compression recovery was evaluated by the ratio (%). This value is large
The higher the value, the better the compression recovery.Foam strength Normal strength: For foam sheets, JIS K630
According to 1, pulling 500 mm / min using No. 2 dumbbell
A tensile test was performed at a tension rate. Water resistance: Foam sheets in normal temperature water at 24:00
After soaking for a while, perform a tensile test in the same manner as normal strength.
It was. The larger this value, the better the water resistance.Weatherability Accelerated carbon arc weather resistance for foam sheets
Foam table after 48 hours exposure at 63 ° C using a tester
Visually observe the condition of the surface and weather resistance according to the following criteria.
The sex was evaluated. ○: No change, △: slightly yellowing, ×: yellowingFoam viscosity Unexpanded when the foaming composition is doubled in volume
The viscosity of the bridge foam was measured using a BM type viscometer, a rotor No. 4 o
And a rotation speed of 12 ppm.

[0061]

[Table 1]

[0062]

[Table 2]

As is clear from Table 2, the foam obtained from the acrylic foam composition of the present invention is excellent in compression recovery, normal strength, water resistance and weather resistance. On the other hand, when the acrylic ester monomer is not contained in a predetermined amount (Comparative Example 1), the monomer having a crosslinkable functional group is not contained in a predetermined amount (Comparative Example 2), and the crosslinkable functional group is added. When the amount of the monomer contained is too large (Comparative Example 3), the compression recovery property is significantly lowered and other properties are also insufficient. On the other hand, when the amount of wax is too large (Comparative Example 4), the normal strength, the water resistance and the weather resistance are all significantly reduced, and the compression recovery property is rather low. Thus, the composition for an acrylic foam of the present invention, in particular, the content of the acrylic ester monomer unit in the acrylic copolymer and the content of the monomer unit having a crosslinkable functional group, By combining the specific conditions, it is possible to form an acrylic foam having excellent properties.

[0064]

The acrylic foam composition of the present invention is comprehensively excellent in various properties such as compression recovery, strength, water resistance and weather resistance as compared with the conventional acrylic foam compositions. It is possible to form a foam which does not lose its shape even after being used for various purposes for a long period of time and which can maintain the original performance of the foam. Therefore, the foam formed from the acrylic foam composition of the present invention can be suitably used as a structural material, a surface material, a material for an intermediate layer, and the like in a wider field as compared with a conventional acrylic foam. ..

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhisa Watanabe 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (2)

[Claims] 1. (1) (a) Acrylic acid ester monomer unit and / or methacrylic acid ester monomer unit 1
Acrylic copolymer consisting of 0 to 99.9% by weight, (B) 0.1 to 10% by weight of a monomer unit having a crosslinkable functional group, and (C) another monomer unit of 0 to 89.9% by weight. An acrylic foam composition comprising 100 parts by weight of a polymer emulsion (converted to solid content) and (2) 0 to 20 parts by weight of a wax. 2. An acrylic foam obtained by foaming and crosslinking the composition for acrylic foam according to claim 1.