JPH06128407A - Acrylic foam cushioning material - Google Patents

Abstract

PURPOSE:To obtain a cushioning material excellent in many characteristics including permanent compression set, recovery to compression, strength, water resistance, weather resistance, heat resistance, etc., and capable of retaining required cushioning performance over a long period even under various environments. CONSTITUTION:This cushioning material uses a crosslinked foam formed from a polymer emulsion of an acrylic acid ester and/or a methacrylic acid ester as a substrate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cushioning material based on a crosslinked foam formed from an emulsion of an acrylic polymer.

[0002]

2. Description of the Related Art Conventionally, foam has been obtained from various materials such as rubber, olefin resin, styrene resin, vinyl chloride resin, acrylic resin, urethane resin, and thermosetting resin. The foam is generally foamed using an organic foaming agent, and particularly rubber latex such as natural rubber latex, chloroprene latex, styrene butadiene rubber latex, and nitrile rubber latex is mechanically foamed to form the foam. .

However, the use of an organic foaming agent such as a volatile solvent or a Freon-based gas at the time of foaming poses a problem in terms of environment and health, and in terms of performance, foam strength,
The weather resistance was not sufficient. Further, the foam obtained by mechanically foaming the rubber latex as described above was not sufficient in water resistance, weather resistance, heat resistance, etc. due to its chemical structure.

On the other hand, foams are widely used as cushioning materials, protective materials, wrapping materials, vibration damping materials, soundproofing materials, packing materials, heat insulating / heat insulating materials, etc. In particular, cushioning materials, protective materials or wrapping materials are packaged, It is used in the fields of building materials, vehicles, furniture, rugs, footwear, and sundries. Further, plastics such as olefin resin, styrene resin, vinyl chloride resin and urethane resin, and rubber such as natural rubber and synthetic rubber are also used for cushioning material, protective material or foam for packaging material. , As described above, these are generally insufficient in weather resistance and heat resistance, and also have low compression recovery and strength,
A major problem is that the buffering performance and the elongation are deteriorated over time, and the use environment and the use place are also restricted. It is also known that an acrylic polymer emulsion is mechanically foamed to form a foam having good water resistance, weather resistance, heat resistance and the like (for example, JP-B-54-284).
No. 25, JP-A-2-264079), this foam is still not always satisfactory in terms of basic properties such as compression recovery and strength.

[0005]

Therefore, the object of the present invention is to provide various characteristics including compression set, compression recovery, strength, weather resistance, water resistance, heat resistance, etc. Another object of the present invention is to provide a cushioning material that can maintain the required cushioning performance.

[0006]

SUMMARY OF THE INVENTION That is, the present invention provides a cushioning material characterized by using a crosslinked foam formed from a polymer emulsion of acrylic acid ester and / or methacrylic acid ester as a base material. To do.

The present invention will be described in detail below, which will clarify the purpose, constitution and effect of the present invention. The cushioning material in the present invention refers to a material used for applications in which an action of absorbing or mitigating an external impact is required. Therefore, the cushioning material also includes so-called protective material or packaging material.

The polymer of acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as "acrylic polymer") used in the present invention is an acrylic acid ester or methacrylic acid ester (hereinafter referred to as acrylic acid ester and methacrylic acid ester). When collectively referred to as acid ester, it is referred to as “acrylic ester”.) Homopolymer or copolymer of two or more acrylic esters, or one or more acrylic ester and one or more other It is a copolymer with the monomer. These acrylic polymers are used alone or in admixture of two or more.

The acrylic ester in the present invention means
It means an ester of acrylic acid or methacrylic acid with an aliphatic, alicyclic or aromatic unsubstituted alcohol. The term "unsubstituted" as used herein means having no substituent other than a hydrocarbon group.

Specific examples of the acrylic ester include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-propyl methacrylate, isopropyl methacrylate, and acrylic. Acid n-butyl, isobutyl acrylate, n-butyl methacrylate,
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, acrylate Undecyl, undecyl methacrylate, dodecyl acrylate,
Dodecyl methacrylate, n-amyl acrylate, isoamyl acrylate, n-amyl methacrylate, isoamyl methacrylate, lauryl acrylate, lauryl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, etc. be able to. A preferred acrylic ester is an alkyl acrylate or an alkyl methacrylate having an alkyl group with 1 to 12 carbon atoms, and more preferably ethyl acrylate, n-butyl acrylate or isononyl acrylate.

Next, in the copolymer of the acrylic ester and another monomer used in the present invention, the other monomer is a monomer having a crosslinkable functional group or a crosslinkable functional group. Mention may be made of monomers without groups.

First, the monomer having a crosslinkable functional group is
A monomer that copolymerizes with an acrylic ester to form a crosslinked acrylic polymer, or simultaneously with or after the formation of a foam, in the presence or absence of a catalyst, and with or without heating. It is a monomer that forms a crosslinked acrylic polymer. In the present invention, it is preferable to use, as the monomer having a crosslinkable functional group, a monomer that causes a crosslinking reaction after forming a foam. Examples of the crosslinkable functional group include a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an amide group, an epoxy group, and a polyfunctional unsaturated bond.

As specific examples of the monomer having a crosslinkable functional group, examples of the monomer having a carboxyl group include ethylene such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid and crotonic acid. Unsaturated monocarboxylic acid or ethylenically unsaturated polycarboxylic acid or salts thereof;

Examples of the monomer having an acid anhydride group include the above-mentioned ethylenically unsaturated polycarboxylic acid anhydrides and the like;

Examples of the monomer having a hydroxyl group include N
-Methylol acrylamide, N-methylol methacrylamide, allyl alcohol, methallyl alcohol, hydroxymethyl acrylate, hydroxymethyl methacrylate, 1-hydroxyethyl acrylate, 1-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, methacrylic acid 2-hydroxyethyl, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Hydroxybutyl acrylate, hydroxybutyl methacrylate, etc .;

Examples of the monomer having an amino group include aminoethyl acrylate, aminoethyl methacrylate,
Dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, β-aminoethyl vinyl ether, dimethylaminoethyl vinyl ether, vinylamine, vinylmethylamine, vinylethylamine, vinyldimethylamine, vinyldiethylamine, allylamine, allyldimethylamine, methallyldiethylamine, vinyl Diphenylamine, allyldimethylamine, methallyldiethylamine, p-aminostyrene, etc .;

Examples of the amide group-containing monomer include acrylamide, methacrylamide, ethacrylamide, diacetone acrylamide, diacetone methacrylamide, crotonamide, itacone diamide, methyl itaconamide, malein diamide, N-butoxymethyl acrylamide, N-butoxymethyl acrylamide. -Butoxymethyl methacrylamide, N-butoxyethyl acrylamide, N-butoxyethyl methacrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, Nn
-Propioxymethylacrylamide, Nn-propoxymethylmethacrylamide, N-methylacrylamide, N-methylmethacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide,
N, N-diethyl acrylamide, N, N-diethyl methacrylamide, etc .;

Examples of monomers having an epoxy group include glycidyl esters of ethylenically unsaturated carboxylic acids such as glycidyl acrylate, glycidyl methacrylate, vinyl glycidyl ether, and allyl glycidyl ether, and glycidyl ethers of ethylenically unsaturated alcohols. ;

Examples of the monomer having a polyfunctional unsaturated bond include divinylbenzene, diacrylate or dimethacrylate of ethylene glycol, diacrylate or dimethacrylate of polyethylene glycol (eg, diethylene glycol), diacrylate of propylene glycol. Or dimethacrylate, diacrylate or dimethacrylate of polypropylene glycol, polyacrylate or polymethacrylate of trimethylolpropane, polyacrylate or polymethacrylate of glycerin, polyacrylate or polymethacrylate of terminal hydroxyl group-containing polyester, diallyl phthalate, etc. .

Further, the monomer having a crosslinkable functional group is
It is also possible to have two or more kinds of crosslinkable functional groups as described above. There are various combinations of crosslinkable functional groups in this case. For example, as monomers having both a carboxyl group and a hydroxyl group, mono (hydroxyethyl) itaconate, mono (hydroxyethyl) maleate, etc. may be mentioned. , Itaconic acid mono (aminoethyl) acid as a monomer having both a carboxyl group and an amino group, maleic acid mono (aminoethyl), etc., as a monomer having both a carboxyl group and an amide group, itaconic acid Monoamide, maleic acid monoamide, etc. are monomers having both a carboxyl group and an epoxy group, monoglycidyl itaconate, monoglycidyl maleate, etc. are monomers having both a hydroxyl group and an amino group, acrylic acid 1 -Amino-2-hydroxyethyl, 1-hydroxy-2-aminoethyl methacrylate, itaconic acid ( Minoethyl) (hydroxyethyl), maleic acid (aminoethyl) (hydroxyethyl), and the like are itaconic acid (hydroxyethyl) (glycidyl), maleic acid (hydroxyethyl) (as a monomer having both a hydroxyl group and an epoxy group). Glycidyl)
Etc. as N-aminoethylacrylamide, N-aminoethyl-methacrylamide, N-dimethylaminomethyl-acrylamide, N-dimethylaminomethyl-methacrylamide, N- as monomers having both an amino group and an amide group. Aminopropyl-acrylamide, N-aminopropyl-methacrylamide, N-dimethylaminopropyl-acrylamide, N-dimethylaminopropyl-methacrylamide and the like are used as a monomer having both an amino group and an epoxy group, itaconic acid (amino acid). ethyl)
Examples of (glycidyl), maleic acid (aminoethyl) (glycidyl) and the like include glycidyl itaconic acid monoamide and glycidyl maleic acid monoamide as monomers having both an amide group and an epoxy group.

These monomers having a crosslinkable functional group can be used alone or in admixture of two or more.

In the present invention, as the monomer having a crosslinkable functional group, a monomer having a single crosslinkable functional group can be used when the functional group itself can cause a crosslinking reaction. However, in other cases, a monomer having two or more functional groups capable of reacting with each other in the same molecule is used, or a functional group capable of reacting with each other is used.
One or more monomers are used in combination.

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 / a hydroxyl group, an acid. Anhydride group /
Examples thereof include an amino group, a hydroxyl group / epoxy group, and an amino group / epoxy group.

Next, as the monomer having no crosslinkable functional group, there are aromatic vinyl monomers, vinyl cyanide monomers, ethylenically unsaturated ester monomers and ethylenically unsaturated monomers. Examples thereof include ether-based monomers, ethylenically unsaturated silane-based monomers, vinyl halide-based monomers, and aliphatic conjugated diene-based monomers.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, o-methylstyrene, p-
Methyl styrene, o-ethyl styrene, p-ethyl styrene, α-chloro styrene, p-chloro styrene, p-
Methoxystyrene, p-aminostyrene, p-acetoxystyrene, sodium styrenesulfonate, α-vinylnaphthalene, sodium 1-vinylnaphthalene-4-sulfonate, 2-vinylfluorene, 2-vinylpyridine, 4-vinylpyridine, etc. Of these, styrene is particularly preferable.

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 ester monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, allyl acetate, methallyl caproate, allyl laurate, allyl benzoate. , Vinyl alkyl sulfonate, allyl alkyl sulfonate, vinyl aryl sulfonate, dimethyl itaconate, diethyl itaconate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, methyl crotonate, ethyl crotonate, vinyl sulfone Examples thereof include methyl acidate, methyl isoprene sulfonate, ethyl vinyl sulfonate, and ethyl isoprene sulfonate.

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

Examples of the ethylenically unsaturated silane-based monomer include vinyltriethylsilane, methylvinyldichlorosilane, dimethylallylchlorosilane, vinyltrichlorosilane and the like.

Examples of the vinyl halide monomer include:
Vinyl fluoride, vinylidene fluoride, 1,2-difluoroethylene, vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl bromide, vinylidene bromide, 1,2-
Dibromoethylene and the like can be mentioned.

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-
1,3-Butadiene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadienes, linear and side chain conjugated hexadienes and the like can be mentioned, with 1,3-butadiene being particularly preferred.

In the present invention, a preferable combination of monomers in the copolymer of acrylic esters is as follows:
A combination of ethyl acrylate / methyl methacrylate (same below), n-butyl acrylate / methyl methacrylate,
2-ethylhexyl acrylate / methyl methacrylate,
Examples thereof include ethyl acrylate / n-butyl acrylate / methyl methacrylate.

Further, as a preferable combination of monomers in the copolymer of an acrylic ester and a monomer having a crosslinkable functional group, (i) ethyl acrylate, n-butyl acrylate and 2-acrylic acid At least one of ethylhexyl, (ii) methyl methacrylate, and (iii)
Examples thereof include at least one of a carboxyl group-containing monomer, (N-methylol) amide group-containing monomer and epoxy group-containing monomer, and more specifically, ethyl acrylate / methacrylic acid. Methyl / methacrylic acid, ethyl acrylate / methyl methacrylate / methacrylic acid / N-methylol acrylamide, ethyl acrylate / n-butyl acrylate / methyl methacrylate / N
-Methylol acrylamide, ethyl acrylate / n-butyl acrylate / methyl methacrylate / methacrylic acid / glycidyl methacrylate / N-methylol acrylamide, and the like.

Next, as a preferable combination of monomers in the copolymer comprising an acrylic ester, a monomer having a crosslinkable functional group and a monomer having no crosslinkable functional group, (i) acrylic acid At least one of ester and / or methacrylic acid ester, (ii) carboxyl group-containing monomer, hydroxyl group-containing monomer, amide group-containing monomer, N-methylolamide group-containing monomer and epoxy group-containing monomer And (iii) at least one of an aromatic vinyl-based monomer and a vinyl cyanide-based monomer, and more specifically, ethyl acrylate /
2-Hydroxyethyl acrylate / acrylamide / acrylonitrile, ethyl acrylate / methacrylic acid / N
-Methylol acrylamide / styrene / acrylonitrile, ethyl acrylate / n-butyl acrylate / methacrylic acid / N-methylol acrylamide / styrene,
Ethyl acrylate / n-butyl acrylate / methyl methacrylate / methacrylic acid / N-methylol acrylamide / acrylonitrile, ethyl acrylate / n-butyl acrylate / 2-hydroxyethyl acrylate / N-
Methylol acrylamide / acrylonitrile, ethyl acrylate / n-butyl acrylate / glycidyl methacrylate / N-methylol acrylamide / acrylonitrile, n-butyl acrylate / 2-hydroxyethyl acrylate / glycidyl methacrylate / styrene, n-butyl acrylate / Glycidyl methacrylate / N-methylol acrylamide / styrene / acrylonitrile /
Butadiene etc. are mentioned.

Further, as a preferable combination of the monomers in the copolymer consisting of the acrylic ester and the monomer having no crosslinkable functional group, (i) an acrylic ester and / or a methacrylic ester and (ii) ) Those containing at least one of an aromatic vinyl-based monomer and a vinyl cyanide-based monomer can be mentioned, and more specifically, ethyl acrylate / styrene, ethyl acrylate /
Acrylonitrile, n-butyl acrylate / styrene,
Examples thereof include n-butyl acrylate / acrylonitrile, n-butyl acrylate / methyl methacrylate / styrene, and n-butyl acrylate / methyl methacrylate / acrylonitrile.

When the acrylic polymer used in the present invention contains a monomer having a crosslinkable functional group, the content of each monomer in the acrylic polymer is usually 10 for acrylic ester. ~ 99.9% by weight, preferably 15-98
% By weight, more preferably 17 to 97% by weight,
The monomer having a crosslinkable functional group is usually 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably 1
˜5% by weight, and the amount of monomers having no crosslinkable functional group is usually 89.9% by weight or less. In the case where the acrylic polymer is a copolymer of an acrylic ester and a monomer having no crosslinkable functional group, that is, in the case of a copolymer containing no monomer having a crosslinkable functional group, ,
The content of the acrylic ester is usually 10% by weight or more, preferably 20 to 90% by weight, more preferably 30 to 80% by weight, and particularly preferably 40 to 75% by weight.

The emulsion of the acrylic polymer used in the present invention contains an acrylic ester, preferably together with a monomer having a crosslinkable functional group, and optionally the presence of a monomer having no crosslinkable functional group. It is preferably produced by emulsion polymerization under an aqueous medium.
Such emulsion polymerization generally uses 100 to 200 parts by weight of water per 100 parts by weight of the total amount of monomers, optionally in the presence of an emulsifier and a polymerization initiator, and optionally a chain transfer agent,
10 to 90 ° by adding various electrolytes, pH adjusters, etc.
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 the other addition components are added in advance in advance, and a part of the monomers or It is also possible to add all in portions or continuously. 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 and the like are used, and 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, Sulfate of aliphatic amine or amide, sulfonate of dibasic fatty acid ester, sulfonate of aliphatic amide, alkyl or alkenyl sulfonate, alkylaryl sulfonate, alkyl sulfosuccinate, formalin condensation Naphthalene sulfonate, a phosphate ester salt of an aliphatic alcohol, a polyoxyethylene alkyl (phenyl) ether phosphate ester salt, and the like are 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.

Specific examples of the nonionic surfactant include polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like. Can be mentioned.

Further, the fluorine-based surfactant that can be used in the emulsion polymerization includes an anionic surfactant having a hydrophilic group such as carboxylate, sulfate, sulfonate, and phosphate. There are nonionic surfactants having a polyoxyethylene group as a hydrophilic group, cationic surfactants having a group such as amine salt and quaternary ammonium salt as a hydrophilic group, and amphoteric surfactants. Fluorine-based surfactants 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. As such a fluorine-based surfactant,
Perfluoroalkyl carboxylate, perfluoroalkyl sulfonate, perfluoroalkyl phosphate ester, perfluoroalkyl trimethyl ammonium salt,
Examples thereof include perfluoroalkyl polyoxyethylene and perfluoroalkyl betaine.

The preferred amount of 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 crosslinked foam formed from the emulsion of the acrylic polymer tends to decrease. Indicates.

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 is preferably contained 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 the acrylic polymer according to the present invention has been described above. In the emulsion of the acrylic polymer, at least the last stage of the polymerization is a polymerization method other than the emulsion polymerization method, for example, It can also be produced by a method of emulsifying and dispersing an acrylic polymer obtained by bulk polymerization, solution polymerization, precipitation polymerization, suspension polymerization, bulk-suspension polymerization, etc. in an aqueous medium. As the emulsifier used in this case,
There may be mentioned various surfactants such as those used in the emulsion polymerization method described above.

The glass transition point of the acrylic polymer in the present invention is usually -60 ° C to + 25 ° C, preferably -30 ° C to + 15 ° C. Glass transition point
If the temperature is lower than 60 ° C, the foam tends to have too strong tackiness to be difficult to handle, and the crosslinked foam tends to have low strength. On the other hand, when the temperature is higher than + 25 ° C, the crosslinked foam is too hard and poor in flexibility, so that the cushioning effect may be insufficient or the use may be restricted.

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

The average particle size of the emulsion of the acrylic polymer in the present invention is usually 120 to 500 nm,
It is preferably 170 to 350 nm. Average particle size is 12
If it is less than 0 nm, the viscosity of the emulsion becomes too high, so that it becomes difficult to obtain an emulsion having a high solid content, and as a result, it becomes difficult to obtain a good molded product. On the other hand, when it exceeds 500 nm, the water resistance and solvent resistance of the crosslinked foam tend to be low. The average particle diameter is a number average of particle diameters 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 polymer emulsion can be controlled by adjusting the stirring conditions during emulsion polymerization, the amount of emulsifier used, and the like.

The emulsion of the acrylic polymer used in the present invention may be blended with a wax and / or a fluorinated silica salt, whereby the compression recovery property of the crosslinked foam and the like can be further improved. .

Specific examples of the wax include oxidized polyethylene wax, oxidized polypropylene wax, glycol-modified oxidized polypropylene wax, ethylene acrylic acid copolymer wax, and paraffin wax. A particularly preferred wax is oxidized polyethylene wax. These waxes can be used alone or in admixture of two or more. These waxes may be added by emulsifying them in advance in order to improve the miscibility of the acrylic polymer with the emulsion.

In the present invention, the amount of the wax to be used is usually 0.2 to 20 parts by weight per 100 parts by weight of the acrylic polymer emulsion (solid content conversion). When the amount of the wax compounded exceeds 20 parts by weight, the strength, water resistance, weather resistance and the like of the crosslinked foam are deteriorated.

As the silicofluoride salt, sodium silicofluoride, potassium silicofluoride, ammonium silicofluoride and the like are used, and preferred silicofluoride salts are sodium silicofluoride and potassium silicofluoride. Particularly preferred is potassium silicofluoride. These silicofluoride salts may be used alone or in admixture of two or more.

In the present invention, the amount of the silicofluoride salt used is 100 parts by weight of the acrylic polymer.
The amount is 0.05 to 10 parts by weight, preferably 0.1 to 8 parts by weight, and particularly preferably 0.5 to 5 parts by weight. If the amount of silicofluoride salt used exceeds 10 parts by weight, the emulsion for forming the foam becomes unstable and gelation easily occurs in the foaming machine, resulting in poor workability.

In the present invention, the silicofluoride salt is added before and / or during the foaming of the acrylic polymer emulsion. At that time, it is preferable to add a part or all of the silicofluoride salt to the foaming of the emulsion. When the silicofluoride salt is added during foaming, the whole amount can be added at once, or a part or the whole amount thereof can be added in a divided or continuous manner.

In the present invention, a preferred method of forming a foam by foaming an acrylic polymer emulsion in the presence of a silicofluoride salt is as follows: when the foaming state of the acrylic polymer emulsion becomes uniform, For example, when the specific gravity of the foaming system reaches about 0.3 to 0.5, a silica fluoride salt is added, and then the temperature is usually set to 80 ° C or higher, preferably about 100 to 130 ° C, and the heating time is set. It is a method of gelling by heating for 10 minutes or more, preferably about 20 to 40 minutes.

In the present invention, ammonium salts such as ammonium acetate, ammonium chloride, ammonium carbonate and ammonium hydrogencarbonate, alkylphenol alkylene oxide adducts, polyvinyl methyl ether,
Polypropylene glycol, polyether polyformal, methyl cellulose, hydroxyethyl cellulose,
A sensitizer such as an alkylene oxide adduct of an alkylphenol formalin condensate, an organopolysiloxane, nitroparaffin, trypsin, or a protein may be used in combination with the silicofluoride salt.

Further, in the present invention, a polyurethane emulsion can be blended with an acrylic polymer emulsion. This polyurethane emulsion is a polyurethane resin and / or polyurethane elastomer finely emulsified and dispersed in an aqueous medium. The polyurethane emulsion is, for example, (a)
A method for obtaining a polyurethane emulsion by emulsifying a diisocyanate component in an aqueous medium in the presence of an emulsifier or a protective colloid, and reacting with addition of a diol component while vigorously stirring. (B) Obtained from a diisocyanate component and a diol component After dispersing a solution of NCO-terminated prepolymer in an organic solvent (such as toluene) in an aqueous medium,
A method of synthesizing polyurethane by adding a diamine component to extend the chain and then emulsifying and dispersing in the presence of a large amount of emulsifier, (c) reacting a diol component with an excess diisocyanate component in an organic solvent By synthesizing the NCO-terminated prepolymer, a hydrophilic group (eg, anionic group, nonionic group, cationic group, etc.) and an NCO-reactive group (eg, hydroxyl group, amino group, etc.) are formed in the molecule. It can be produced by a method of reacting an internal emulsifier contained therein to synthesize an ionomer, emulsifying and dispersing the ionomer in an aqueous medium, and removing the solvent.

Examples of the diisocyanate component include toluene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, xylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate. Examples of the diol component include polyethylene glycol, polypropylene glycol, polyether glycol, polyester glycol, and polyether polyester glycol. These diisocyanate components and diol components may be used alone or in admixture of two or more.

When a polyurethane emulsion is blended in the present invention, the mixing ratio of the acrylic polymer emulsion and the polyurethane emulsion is usually 95/5 to 5/95 in terms of solid content.

Further, in the present invention, if necessary,
An alkoxysilane compound may be added to the acrylic polymer emulsion. Specific examples of the alkoxysilane compound include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and n-propyltrisilane. Methoxysilane, n
-Propyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, isopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyl Triethoxysilane, 3,3,3-tolufluoropropyltrimethoxysilane, 3,3,3-tolufluoropropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysila Amine, phenyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3,4-
Epoxycyclohexylethyltrimethoxysilane,
Examples include 3,4-epoxycyclohexylethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane and the like. Preferred silane compounds are tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane and dimethyldiethoxysilane. These alkoxysilane compounds can be used alone or in combination of two or more.

In the present invention, the amount of the alkoxysilane compound used is usually 0.1 per 100 parts by weight of the total solid content of the acrylic polymer emulsion.
~ 80 parts by weight.

In the emulsion of the acrylic polymer in the present invention, if necessary, a flame retardant, a filler, a gelling agent, a foaming aid, a foam stabilizer, a thickener, a dispersant, a wetting agent, and a defoaming agent. Additives such as an agent, an antiaging agent, an ultraviolet absorber and an antiseptic can be further mixed.

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 filler include calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, barium hydroxide, basic zinc carbonate, basic lead carbonate, ferric hydroxide, silica sand, clay and diatomaceous earth. Is 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 aid include sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium polyoxyethylene alkylphenol ether sulfate and the like.

Examples of the foam stabilizer include ammonium stearate, alkylsulsuccinate, quaternary alkylammonium chloride and the like. Examples of the bubble stabilizer include ammonium stearate, alkyl sulfosuccinate, Nopco DC-100A (trade name, manufactured by San Nopco), ALCOPOL-FA (trade name, manufactured by Allied Colloid in the United States) and the like.

Examples of the thickener include sodium polyacrylate, polyvinyl alcohol, sodium alginate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, casein, starch, Aron-20L (trade name, manufactured by Toagosei Chemical Industry Co., Ltd.) and the like. To be

Examples of the dispersant include sodium tripolyphosphate and sodium hexametaphosphate.

Examples of the wetting agent include sodium salt of di (2-ethylhexyl) sulfosuccinate, 2
-A mixture of ethylhexanol and urea, Nopco Wet 50 (trade name, manufactured by San Nopco Ltd.) and the like can be mentioned.

As the defoaming agent, for example, an emulsion in which a white filler is mixed with dimethylpolysiloxane, KM
-71 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

Examples of the antiaging agent include 4,4 '
-Dioctyldiphenylamine, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, triethyleneglycol-bis [3- (3-t-butyl-5) -Methyl-4-hydroxyphenyl) propionate], tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, triphenylphosphite,
Examples include tris (2-ethylhexyl) phosphite, tetraphenyldipropylene glycol diphosphite, cyclic neopentanetetraylbis (nonylphenylphosphite), and the like.

Examples of the ultraviolet absorber include pt
-Butylphenyl salicylate, 2-hydroxy-4-
Methoxybenzophenone, 2,2'-dihydroxy-4
-Methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,2 ',
4,4'-tetrahydroxybenzophenone, 2-
(2'-Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy) -3 ', 5'-di-t
-Amylphenyl) benzotriazole, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3-diphenylacrylate, 2-hydroxy-4-benzyloxybenzophenone, bis (2,2) , 6,6-Tetramethyl-4-piperidyl) sebacate, 8-benzyl-7,7,9,9-
Tetramethyl-3-octyl-1,2,3-triazaspiro [4,5] -undecane-2,4-dione, tetraxy (2,2,6,6-tetramethyl-4-piperidyl) -1,2, 3,4-butane tetracarboxylate and the like can be mentioned.

Examples of the preservatives include dihydroxydichlorodiphenylmethane, sodium pentachlorophenate, 2,3,4,6-tetrachloro-4- (methylsulfanyl) pyridine, 2,3,5,6-tetrachloro- 4- (methylsulfonyl) pyridine, bis (tributyltin) oxide, hexahydro-1,3,5-triethyl-s-triazine, 10,10'-oxybisphenoxyarsine, 1,2-benzisothiazoline-
3-one, dithio-2,2'-bis (benzmethylamide), N-dimethyl-N'-phenyl (N'-florodichloromethylthio) -sulfamide and the like can be mentioned.

The amount of these additives used is usually 2 to 50 parts by weight of the flame retardant and 2 to 20 parts by weight of the filler per 100 parts by weight of the acrylic polymer emulsion (calculated as total solids).
0 parts by weight, 0.05 to 5 parts by weight of gelling agent, 0.1 to 10 parts by weight of foaming aid, 0.1 to 10 parts by weight of foam stabilizer, and 0.05 to 10 parts by weight of thickener. Parts, 0.1 to 5 parts by weight of a dispersant, 0.1 to 3 parts by weight of a wetting agent, and 0.01 to an antifoaming agent.
0.5 parts by weight, 0.05-5 parts by weight of anti-aging agent, 0.05-5 parts by weight of ultraviolet absorber, 0.01-1 of preservative
It is about part by weight.

Further, in the present invention, a rubber latex such as natural rubber latex, styrene butadiene rubber latex, acrylonitrile butadiene rubber latex, chloroprene rubber latex, a vinyl chloride resin emulsion or a styrene resin emulsion is added to the acrylic polymer emulsion. It is also possible to mix a resin emulsion such as a silicone-based resin emulsion or the like, whereby the characteristics of the buffer material of the present invention can be balanced.

The total solid content of the acrylic polymer emulsion in the present invention is preferably 55 to 85% by weight, more preferably 60% to 85% by weight. Also,
When a foam formed from the emulsion is expanded by a volume of 2 times, the viscosity of the uncrosslinked foam is 2,000.
˜70,000 cps (however, measured under conditions of BM type viscometer, rotor No. 4 and rotation speed 6 rpm).

The cushioning material of the present invention comprises an acrylic polymer,
It is based on a crosslinked foam formed from an emulsion, which optionally contains the above-mentioned various components and additives. The cushioning material having a crosslinked foam as a base material here means a cushioning material having a crosslinked foam as a main material. Therefore, the cushioning material of the present invention can be composed of a crosslinked foam alone formed from an emulsion of an acrylic polymer, or can be a composite or combination of the crosslinked foam with another material.

In the present invention, the crosslinked foam can be produced at the time of producing the acrylic polymer, or at the same time as forming the foam from the emulsion of the acrylic polymer or at the same time after the formation of the foam, by introducing a crosslinked structure. However, it is particularly preferable to crosslink the foam after formation.

In this case, when the constituent unit of the acrylic polymer contains a monomer having a crosslinkable functional group, a crosslinked foam can be formed by a crosslinking reaction by the crosslinkable functional group. When the system polymer does not contain the above-mentioned monomer having a crosslinkable functional group, a crosslinking agent must be further added to the acrylic polymer emulsion. In this latter case, the acrylic polymer itself does not crosslink, but as a result of the molecular chain of the acrylic polymer being constrained by the crosslinked structure formed by the crosslinker, the foam as a whole has a crosslinked form. It is possible to exhibit the characteristics. As the cross-linking agent, other than the one which causes the cross-linking reaction by itself, one which reacts with the functional group in the acrylic polymer to form a cross-linking bond can be used.

Examples of the cross-linking agent include phenol resin, urea resin, amino resin, aniline resin, melamine resin, epoxy resin, azo compound, isocyanate compound, peroxide and zinc.

In the cushioning material of the present invention, since the foam as the base material has a crosslinked structure, the compression recovery property,
It has excellent properties such as strength.

In the present invention, when a foam is formed from an acrylic polymer emulsion, a gas (preferably air or the like) is introduced and the mixture is foamed by mechanically stirring it with an Oaks mixer, a whipper or the like. It is preferable. This foaming operation can be carried out continuously or discontinuously. The expansion ratio is usually 1.5
It is 10 times, preferably 2 to 7 times. The bulk specific gravity of this foam is usually in the range of 0.05 to 0.9 immediately after foaming.

The foam formed as described above is
After being applied to another substrate as necessary, it is usually at a temperature of 80 ° C or higher, preferably 100 to 170 ° C, and usually 10
It is heated and dried for a minute or more, preferably about 15 to 40 minutes. In a preferred embodiment of the present invention, a crosslinked structure is introduced into the foam during the heating / drying step. The foam density after drying is preferably about 0.05 to 0.8 g / cm ³ .

The cell structure of the crosslinked foam formed as described above is composed of closed cells and communicating cells (a plurality of cells communicating with each other). Such a cell structure has various types of acrylic polymer, average particle size and total solid content of emulsion of acrylic polymer, stirring conditions, amount of input gas, type and amount of foaming aid or foam stabilizer, and By adjusting the viscosity and the like of the crosslinked foam, the cushioning material is adjusted so as to have desired properties.

The shape, thickness, dimensions, etc. of the cushioning material of the present invention are as follows.
It is appropriately selected according to the purpose of use. For example, regarding the shape, it is possible to appropriately select a film, a sheet, a tape, a block, a line, a trapezoid, a cylinder, a prism, a hollow body, a special shape, or a container shape such as a box, a bottle, a case, a tray, a container, or a pallet. it can. The cushioning material having these shapes can be directly formed in the step of forming a foam from an emulsion of an acrylic polymer, or cutting, cutting, or the like of a crosslinked foam formed in a wide width or a thick wall, or formed in advance. It can also be formed by secondary processing such as fixing and joining of parts.

When the cushioning material of the present invention is made into a composite or combination of the above crosslinked foam and another material, a two-layer structure of the crosslinked foam and another material, or the crosslinked foam with another material. It can be a sandwiched structure, or it can be pre-disposed in another structural material or pre-assembled in another structural part. Further, the cushioning material of the present invention can be incorporated into a paint in the form of particles to be used as a buffering protective paint.

Other materials to be combined with or combined with the cushioning material of the present invention include wood materials (for example, veneer, plywood, particle board, etc.) and inorganic materials (for example, stone, natural), depending on the purpose of use. Minerals, glass, ceramics,
Concrete, etc.), metal (eg iron / steel, aluminum, various alloys, reinforced metals, etc.), plastic (eg thermoplastics, thermosetting plastics, reinforced plastics, etc.), rubber (eg natural rubber, synthetic rubber, thermoplastic elastomer) Etc.), fibrous materials (eg woven, knitted,
Styrene resins such as non-crosslinked acrylic resins, olefin resins, ABS resins, etc. other than non-foams such as paper) and leather (for example, natural leather, synthetic leather, etc.) and cross-linked foams made of acrylic polymers. In addition to foams such as vinyl chloride resin, urethane resin, epoxy resin, urea resin and phenol resin, foams such as sintered metal and cork can be appropriately selected and used. If necessary, the cushioning material of the present invention may be coated with a pressure-sensitive adhesive to impart bondability, or may be subjected to surface treatment such as embossing, printing, painting or the like.

The cushioning material of the present invention is excellent in various properties such as compression recovery, elasticity, strength, water resistance, weather resistance, heat resistance, solvent resistance, and the like, and is subjected to high load or repeated load, wet environment or water environment. ,
Even under conditions such as a non-aqueous environment, an oxidizing environment, a warm environment or a thermal environment, an excellent buffering effect can be effectively exhibited for a long period of time. The secondary workability is also good.

The cushioning material of the present invention is a general packaging in various shapes such as a film, a sheet, a tape, a box, a bottle, a case, a tray, a container, a pallet, a lining for packaging,
Packing materials such as fillers or pads, automobile interiors (eg floors, armrests, headrests, seat cushions, bumpers, etc.), chair upholstery, carpet lining, tatami mats, sports protectors and supporters, ski cases, ships Fenders, vehicle and ship dampers, footwear soles, insoles, bicycle saddles, etc., as well as skin materials such as chairs, sofas, mats, duvets, pillows, hats, belts, bags, Boston bags, handbags, and footwear. It can be suitably used as a core material.

The cushioning material of the present invention has a damping function, a soundproofing function, a heat retaining / heat insulating function, etc. in addition to the cushioning function, and these various functions are comprehensively exhibited in the above-mentioned applications.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it will be apparent to those skilled in the art that the present invention is not limited to these Examples.
Here, parts are based on weight.

EXAMPLES Production of Polymer Emulsion (1) 200 parts of distilled water and potassium carbonate of 0.
Polymer emulsion shown in Table 1 was prepared by charging 8 parts, 0.03 part of acidic sodium sulfite, 0.3 part of potassium persulfate, and the monomer and emulsifier shown in Table 1 and polymerizing at 70 ° C for 5 hours. A to C were produced. Polymerization conversion rate is 98
Reached over%.

(2) 200 parts of distilled water, 0.8 part of potassium carbonate, 0.03 part of sodium acid sulfite,
0.3 parts of potassium persulfate, and the monomer and emulsifier shown in Table 2 were charged and polymerized at 70 ° C. for 5 hours to produce polymer emulsions DG shown in Table 2. The polymerization conversion rate reached 98% or more in all cases.

(3) 200 parts of distilled water, 0.2 part of potassium carbonate, 0.03 part of sodium acid sulfite in a reaction vessel,
0.3 parts of potassium persulfate, and the monomer and emulsifier shown in Table 3 were charged and polymerized at 70 ° C. for 5 hours to produce polymer emulsions HM shown in Table 3. The polymerization conversion rate reached 98% or more in all cases.

Preparation of Foam Composition To 100 parts by weight of each of the polymer emulsions A to M shown in Tables 1 to 3 (as solid content), the compounding ingredients and additives shown in Tables 4 to 5 (see below) were added. By thoroughly mixing, foam compositions (A) to (S) were prepared (where (S) is a foam composition comprising an emulsion of a non-crosslinked acrylic polymer for comparison). Further, for comparison, a foam composition (C) in which the polymer emulsion consisted only of polyurethane emulsion was prepared in the same manner.

Additives Foaming aid: Sodium lauryl sulfate or alkyl sulfosuccinate Foam stabilizer: Ammonium stearate or potassium oleate Thickener: Sodium polyacrylate

Preparation of Foam Sheet Air was added to each of the foam compositions shown in Tables 4 to 5 to mechanically stir with a whipper to foam, and then applied to a substrate made of a non-woven fabric, and then 120 ~ 135 ° C
Heat and dry for 30 minutes at a foam density of 0.3 g / c
Crosslinked foam sheets (Examples 1 to 12) and uncrosslinked foam sheets (Comparative Examples 1 and 2) having m ³ thicknesses of 2 mm and 5 mm were prepared.

Evaluation of Characteristics of Foam Sheet Each property of the foam sheet produced as described above was evaluated in the following manner. The evaluation results are shown in Tables 6 to 8.

Compression set: A 5 mm thick foam sheet is compressed to 50% of its original thickness with compression plates parallel to both sides,
After standing still in a gear oven maintained at a temperature of 70 ± 1 ° C. for 22 hours, it was taken out and the thickness was measured after 30 minutes. The compression set (%) is expressed by 100 × (T ₁ −T ₂ ) / T ₁ (where T _{1 is} the thickness before the test and T _{2 is} the thickness after the test), and the smaller this value is, , Shows that the foam has excellent elasticity. Compression recovery: 4 for a 2mm thick foam sheet
The pressure of kg / cm ² was applied for 10 minutes, and the compression recovery property was evaluated by the ratio (%) of the thickness 10 seconds after the pressure was released to the original thickness. The larger this value is, the better the compression recovery is.

Foam strength: Normal strength: For a 2 mm thick foam sheet, JI
500 according to SK6301 using No. 2 dumbbell
Tensile tests were performed at a pull rate of mm / min. Water resistance strength: A foam sheet having a thickness of 2 mm was immersed in normal temperature water for 24 hours and then subjected to a tensile test in the same manner as the normal strength. The larger this value, the better the water resistance.

Weather resistance: A foam sheet having a thickness of 2 mm was measured with a carbon arc type weather resistance accelerating tester to obtain 63
The state of the foam surface after 48 hours of exposure at ° C was visually observed, and the weather resistance was evaluated according to the following criteria. ○: No change, △: slightly yellowing, ×: yellowing

Viscosity of uncrosslinked foam: The viscosity of the uncrosslinked foam when the foam composition is expanded by a volume of 2 times, the viscosity of the BM type viscometer, rotor No. 4 and rotation speed 6
It was measured in ppm.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

[Table 3]

[0107]

[Table 4]

[0108]

[Table 5]

[0109]

[Table 6]

[0110]

[Table 7]

[0111]

[Table 8]

As is clear from Tables 6 and 7, the cushioning material of the present invention uses a cross-linked foam formed from an emulsion of an acrylic polymer as a base material, so that the compression set, compression recoverability, Strength, water resistance, weather resistance,
Various characteristics such as vibration damping are extremely excellent. On the contrary,
As shown in Table 8, when the foam base material made of an acrylic polymer does not have a crosslinked structure (Comparative Example 1), the compression set is large and the compression recovery property, the strength and the water resistance are significantly reduced. In addition, the weather resistance is insufficient, and in the case of a foam substrate made of non-crosslinked polyurethane (Comparative Example 2), compression set, strength, water resistance, weather resistance are extremely low, and compression recovery is also poor. It is enough.

[0113]

INDUSTRIAL APPLICABILITY The cushioning material of the present invention has a small compression set and excellent elasticity, and further has compression recovery, strength, water resistance, and
It has excellent general properties such as weather resistance, heat resistance and solvent resistance, and can be suitably used in a wide range of fields with different environments. Moreover, the cushioning material of the present invention, together with its excellent compression recovery, water resistance, weather resistance, heat resistance, solvent resistance, etc., can stably maintain the required cushioning performance for a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhisa Watanabe 2-11-21 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A cushioning material, which is based on a crosslinked foam formed from a polymer emulsion of acrylic acid ester and / or methacrylic acid ester.