Latex for adhesive composition and adhesive composition

Abstract

To provide an adhesive composition capable of obtaining strong adhesion within a short time.SOLUTION: Provided is an adhesive composition comprises: (1) a latex (A) for an adhesive composition comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2), and an aqueous medium, wherein the polymer (a1) of the ethylenically unsaturated monomer has a carboxyl group, and an average particle size of the polymer (a1) of the ethylenically unsaturated monomer is from 0.30 to 5.00 μm; (2) a latex (A) for an adhesive composition comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2) and an aqueous medium, the polymer (a1) of the ethylenically unsaturated monomer comprises a latex for an adhesive composition having a carboxyl group and a crosslinking structure; and (3) a latex (A) for the adhesive composition and a chloroprene-based polymer latex (B).

Description

[Technical Field]

[0001] The present invention relates to a latex for an adhesive composition and an adhesive composition. In particular, the present invention relates to a latex for an adhesive composition containing a polymer of an ethylenically unsaturated monomer, and an adhesive composition containing the latex for an adhesive composition and a chloroprene-based polymer latex. [Background technology]

[0002] Conventionally, polymers used for adhesives include vinyl acetate polymers, chloroprene polymers, acrylic ester polymers, natural rubber, and urethane polymers. Chloroprene polymers, among others, are suitable for use in adhesive applications such as solvent-based contact adhesives and graft adhesives because they can provide high adhesive strength with low pressure to a wide range of adherends. In recent years, in response to requirements for volatile organic compound (VOC) and solvent regulations, there has been active development of chloroprene rubber-based water-based adhesives using chloroprene polymer latexes.

[0003] Chloroprene polymer latex crystallizes upon drying, which has the advantage of short adhesive strength development time, i.e., contact resistance. However, the initial adhesive strength of chloroprene polymer latex alone is insufficient for use as a one-component aqueous adhesive composition. Therefore, blending with other polymers has been investigated to improve properties such as initial adhesive strength.

[0004] For example, Patent Document 1 discloses a method of blending polychloroprene latex with an acrylic resin polymer latex or a urethane resin polymer latex. Furthermore, Patent Document 2 discloses a technique in which polyoxyalkylene alkyl ether sulfate and a pH adjuster are added as additives to polychloroprene latex. Furthermore, Patent Document 3 discloses a technique in which an acrylic resin latex and a polyoxyalkylene alkyl ether sulfate as a surfactant are added to a chloroprene polymer latex. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-195406 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-332207 [Patent Document 3] International Publication No. 2011 / 065524 (European Patent No. 2508560) Summary of the Invention [Problem to be solved by the invention]

[0006] However, since each latex has a different stable pH range, the initial adhesive strength is insufficient when the latexes are simply blended as in Patent Document 1. Furthermore, when an attempt is made to ensure the stability of the latex by using a surfactant as in Patent Documents 2 and 3, the amount of surfactant used increases, which causes a problem that gelation of the chloroprene polymer during drying does not proceed easily and a sufficient initial adhesive strength cannot be ensured. In view of the above, an object of the present invention is to provide a latex for an adhesive composition which, when mixed with a chloroprene polymer latex, provides strong adhesive strength in a short period of time. Another object of the present invention is to provide an adhesive composition that can provide strong adhesive strength in a short period of time. [Means for solving the problem]

[0007] The present invention, which solves the above problems, comprises the following [1] to

[21] . [1] A latex (A) for an adhesive composition, comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2), and an aqueous medium, wherein the polymer (a1) of the ethylenically unsaturated monomer has a carboxy group, and the average particle size of the polymer (a1) of the ethylenically unsaturated monomer is 0.30 to 5.00 μm. [2] The latex for an adhesive composition according to item 1 above, wherein the polymer (a1) of the ethylenically unsaturated monomer has an average particle size of 0.50 to 3.00 μm. [3] The latex for an adhesive composition according to the above item 1 or 2, wherein the polymer (a1) of an ethylenically unsaturated monomer has a structural unit derived from an ethylenically unsaturated monomer having a carboxy group and a structural unit derived from an ethylenically unsaturated monomer having a functional group reactive to a carboxy group. [4] The latex for an adhesive composition according to any one of items 1 to 3 above, wherein the polymer (a1) of an ethylenically unsaturated monomer has a structural unit derived from a crosslinkable ethylenically unsaturated monomer having a plurality of ethylenically unsaturated bonds in the molecule.

[0008] [5] The latex for an adhesive composition according to any one of the above items 1 to 4, wherein the polymer (a1) of an ethylenically unsaturated monomer has a crosslinked structure. [6] A latex (A) for an adhesive composition, comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2), and an aqueous medium, wherein the polymer (a1) of an ethylenically unsaturated monomer has a carboxy group and a crosslinked structure. [7] The latex for an adhesive composition according to any one of items 1 to 6, wherein the polymer (a1) of an ethylenically unsaturated monomer contains at least one of a structural unit derived from an ethylenically unsaturated monomer having an epoxy group, a structural unit derived from a silane coupling agent having an ethylenically unsaturated bond, and a structural unit derived from a monomer containing two or more ethylenically unsaturated bonds. [8] The latex for an adhesive composition according to any one of items 1 to 7 above, wherein the polymer (a1) of an ethylenically unsaturated monomer contains a structural unit derived from an ethylenically unsaturated monomer having two or more carboxy groups in the molecule.

[0009] [9] The latex for an adhesive composition according to any one of items 1 to 8, wherein the polymer (a1) of an ethylenically unsaturated monomer contains a structural unit derived from an ethylenically unsaturated monomer having one or more hydroxyl groups in the molecule.

[10] The latex for an adhesive composition according to any one of items 1 to 9, wherein the polymer (a1) of an ethylenically unsaturated monomer contains at least one of (meth)acrylic acid and itaconic acid as a constituent monomer unit.

[11] The surfactant (a2) is represented by the following general formula (1): [ka] 11. The latex for an adhesive composition according to any one of items 1 to 10 above, containing a surfactant represented by the formula: (wherein R represents a hydrocarbon skeleton containing at least one selected from the group consisting of a saturated or unsaturated aliphatic skeleton having an average of 5 to 20 carbon atoms, a saturated or unsaturated alicyclic skeleton having an average of 5 to 20 carbon atoms, and an aromatic ring skeleton having an average of 1 to 10 ring structures; M represents sodium or ammonium; and n (average value) is 2 to 60).

[12] The latex for an adhesive composition according to any one of items 1 to 11 above, having a degree of neutralization of 0.3 to 1.3.

[13] An adhesive composition comprising the latex for adhesive compositions (A) according to any one of items 1 to 12 above and a chloroprene polymer latex (B).

[0010]

[14] The adhesive composition according to item 13 above, wherein the chloroprene polymer latex (B) contains an anionic surfactant having a carboxy group.

[15] The adhesive composition according to item 13 or 14, wherein the mixing ratio of the latex for adhesive compositions (A) to the chloroprene polymer latex (B) is 10:90 to 90:10 by mass ratio of solid contents.

[16] The adhesive composition according to any one of items 13 to 15, wherein a mixing ratio of the latex for adhesive compositions (A) to the chloroprene polymer latex (B) is 25:75 to 70:30 in terms of mass ratio of solid contents.

[17] The adhesive composition according to any one of items 13 to 16, further comprising a pH adjuster.

[18] An article in which porous members are bonded to each other, or a porous member and another member are bonded with the adhesive composition according to any one of items 13 to 17 above.

[19] An article in which water-absorbent members are bonded to each other, or a water-absorbent member and another member are bonded with the adhesive composition according to any one of the preceding paragraphs 13 to 17.

[20] Furniture or automobile interior components using the article described in the preceding paragraph 18 as cushioning material.

[21] Building materials whose structure includes the items set forth in the preceding paragraph 19. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a latex for an adhesive composition which, when mixed with a chloroprene polymer latex, provides strong adhesive strength in a short period of time. Furthermore, according to the present invention, it is possible to provide an adhesive composition that can provide strong adhesive strength in a short period of time. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described. In this specification, the adhesive composition means a chloroprene rubber-based adhesive. In this specification, "to" means equal to or greater than the value before "to" and equal to or less than the value after "to". In this specification, "(meth)acrylic" is a general term for acrylic and methacrylic, and "(meth)acrylate" is a general term for acrylate and methacrylate. In this specification, the term "solid content" refers to all components other than the solvent.

[0013] The adhesive composition of the present invention comprises a latex for adhesive compositions (A), a chloroprene polymer latex (B), and an aqueous medium. The initial adhesive strength and contact properties of the adhesive composition of the present invention are achieved by the promotion of gelation by the latex (A) and the crystallization of the chloroprene polymer, and the adhesive mechanism is different from that of general acrylic pressure-sensitive adhesives. Each component contained in the adhesive composition will be described below.

[0014] [Latex for adhesive composition (A)] Two embodiments of the latex (A) for an adhesive composition according to the present invention will be described below, but the present invention is not limited to these two embodiments. In the following description, the latex (A1) for an adhesive composition in Embodiment 1 and the latex (A2) for an adhesive composition in Embodiment 2 are each one of the embodiments of the latex (A) for an adhesive composition. The polymer (a11) of an ethylenically unsaturated monomer in Embodiment 1 and the polymer (a21) of an ethylenically unsaturated monomer in Embodiment 2 are each one of the embodiments of the polymer (a1) of an ethylenically unsaturated monomer. The surfactant (a12) in Embodiment 1 and the surfactant (a22) in Embodiment 2 are each one of the embodiments of the surfactant (a2).

[0015] In the above two aspects, the configuration according to one aspect does not exclude the configuration according to the other aspect, and the configuration according to one aspect may combine with the configuration according to the other aspect as long as the effects of the present invention are obtained. For example, the polymer (a11) of an ethylenically unsaturated monomer contained in the latex for an adhesive composition (A1) according to aspect 1 described below may have a structural unit derived from a crosslinkable ethylenically unsaturated monomer, which is a constituent of the polymer (a11) of an ethylenically unsaturated monomer contained in the latex for an adhesive composition (A2) according to aspect 2, and may have a crosslinked structure.

[0016] 1. Aspect 1 of latex (A) for adhesive composition A latex (A1) for an adhesive composition according to one embodiment of the present invention (sometimes referred to as "latex (A1)") comprises a polymer (a11) of an ethylenically unsaturated monomer, a surfactant (a12), and an aqueous medium, wherein the polymer (a11) of the ethylenically unsaturated monomer has a carboxy group and an average particle size of 0.3 to 5.0 μm. The polymer (a11) of the ethylenically unsaturated monomer may have a crosslinked structure (described in detail in Aspect 2 below).

[0017] The carboxyl group in the polymer (a11) of an ethylenically unsaturated monomer promotes gelation of the chloroprene polymer when the adhesive composition of the present invention, in which the latex (A1) and the chloroprene polymer latex (B) are mixed, is used, and excellent initial adhesive strength and contact properties can be achieved.

[0018] It is known that gelation of the chloroprene polymer latex (B) is promoted as the pH decreases, followed by crystallization of the chloroprene polymer, resulting in the development of initial adhesive strength. When the latex (A1) has a carboxy group, which is a weak acid, the adhesive composition obtained by mixing the latex (A1) and the chloroprene polymer latex (B) does not gel during storage and has good storage stability. On the other hand, when the adhesive composition of the present invention is used, the water-containing dispersion medium is removed, so the pH in the system is lowered, and the gelation of the chloroprene polymer proceeds rapidly, thereby developing adhesive strength.

[0019] The number of moles of carboxy groups contained per kg of solid content in the latex for adhesive composition (A1) is preferably 0.01 to 1.00 mol, more preferably 0.05 to 0.50 mol, and even more preferably 0.10 to 0.40 mol. When the number of moles of carboxy groups contained per kg of solid content in the latex for adhesive composition (A1) is 0.01 mol or more, excellent initial adhesive strength and contact property can be exhibited when mixed with the chloroprene polymer latex (B) described below. When the number of moles of carboxy groups contained per kg of solid content in the latex for adhesive composition (A1) is 1.00 mol or less, storage stability is improved when mixed with the chloroprene polymer latex (B) described below.

[0020] 1-1. Polymer of ethylenically unsaturated monomer (a11) The structural unit constituting the polymer (a11) of an ethylenically unsaturated monomer is not particularly limited as long as it is a monomer having an ethylenically unsaturated bond. Examples of monomers having an ethylenically unsaturated bond include (meth)acrylic acid, fumaric acid, maleic acid and their esters; (meth)acrylamide and its derivatives; styrene and its derivatives; vinyl esters; N-substituted maleimide compounds; itaconic acid, crotonic acid, phthalic acid and their esters, as well as their metal salts and ammonium salts. The monomers having an ethylenically unsaturated bond can be used alone or in combination of two or more.

[0021] 1-1-1. Ethylenically unsaturated monomers having a carboxy group To introduce a carboxy group into the polymer (a11) of an ethylenically unsaturated monomer, it is preferable to use an ethylenically unsaturated monomer having a carboxy group as a monomer. Examples of the ethylenically unsaturated monomer having a carboxy group include (meth)acrylic acid, itaconic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, crotonic acid, maleic acid, citraconic acid, mesaconic acid, fumaric acid, aconitic acid, and anhydrides of these acids. Among these, it is more preferable to contain at least one selected from the group consisting of (meth)acrylic acid and itaconic acid.

[0022] The total amount of structural units derived from ethylenically unsaturated monomers having a carboxy group is preferably 0.5 to 5.0 mass% and more preferably 1.0 to 4.0 mass% relative to the total amount of structural units derived from all ethylenically unsaturated monomers constituting polymer (a11). More preferably, of all structural units derived from ethylenically unsaturated monomers, structural units derived from (meth)acrylic acid and structural units derived from itaconic acid account for 1.0 to 4.0 mass%. When the structural units derived from ethylenically unsaturated monomers having a carboxy group account for 0.5 mass% or more of all structural units derived from ethylenically unsaturated monomers, the gelation rate of the adhesive composition mixed with the chloroprene polymer latex (B) described below increases, improving contact properties. On the other hand, when the structural units derived from ethylenically unsaturated monomers having a carboxy group account for 5.0 mass% or less of all structural units derived from ethylenically unsaturated monomers, the viscosity of the adhesive composition mixed with the chloroprene polymer latex (B) decreases, improving coatability.

[0023] 1-1-2. Hydrophobic ethylenically unsaturated monomers In addition to the carboxyl-containing ethylenically unsaturated monomer, the polymer (a11) may preferably contain a hydrophobic ethylenically unsaturated monomer. The hydrophobic ethylenically unsaturated monomer is an ethylenically unsaturated monomer that contains at least one group selected from aromatic groups, saturated and unsaturated alicyclic groups, and saturated and unsaturated alkyl groups having 5 or more carbon atoms, but does not contain a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfo group, or an amino group.

[0024] Examples of these hydrophobic ethylenically unsaturated monomers include styrene derivatives, (meth)acrylic acid esters, fumaric acid esters, maleic acid esters, vinyl esters, N-substituted maleimide compounds, itaconic acid esters, crotonic acid esters, and phthalic acid esters. Specific examples include 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, di-(2-ethylhexyl)fumarate, di-(2-ethylhexyl)maleate, styrene, methoxystyrene, divinylbenzene vinyl caprate, vinyl laurate, vinyl stearate, cyclohexylmaleimide, phenylmaleimide, benzylmaleimide, naphthylmaleimide, di-(2-ethylhexyl)itaconate, 2-ethylhexylcrotonate, dihexylphthalate, and di-(2-ethylhexyl)phthalate. The hydrophobic ethylenically unsaturated monomers can be used alone or in combination of two or more.

[0025] Of all the ethylenically unsaturated monomers constituting the acrylic acid polymer (a11), the hydrophobic ethylenically unsaturated monomer is preferably contained in an amount of 50.0 to 99.5% by mass, more preferably 50.0 to 98.0% by mass. When the hydrophobic ethylenically unsaturated monomer is contained in the total ethylenically unsaturated monomers in an amount of 50.0% by mass or more, the storage stability of the adhesive composition mixed with the chloroprene polymer latex (B) described below is improved. On the other hand, when the hydrophobic ethylenically unsaturated monomer is contained in the total ethylenically unsaturated monomers in an amount of 99.5% by mass or less, the gelation rate of the adhesive composition mixed with the chloroprene polymer latex (B) is increased, thereby improving the contact property.

[0026] 1-1-3. Surfactants with ethylenically unsaturated bonds The polymer (a11) of an ethylenically unsaturated monomer preferably contains a structural unit derived from a surfactant having an ethylenically unsaturated bond. This is because the dispersion stability of the particles is improved. Ethylenically unsaturated monomers having a carboxy group are not included in the surfactants having an ethylenically unsaturated bond. Examples of surfactants having an ethylenically unsaturated bond include compounds represented by the following chemical formulas (2) to (5). The symbols in the formulas have the same meanings as in general formula (1) described below. [ka] [ka] [ka] [ka]

[0027] 1-1-4. Other ethylenically unsaturated monomers The ethylenically unsaturated monomer in the present invention may also include ethylenically unsaturated monomers other than ethylenically unsaturated monomers having a carboxy group and hydrophobic ethylenically unsaturated monomers.Specifically, ethylene glycol di(meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, ethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polyethylene glycol polytetramethylene glycol mono(meth)acrylate, polypropylene glycol polytetramethylene glycol mono(meth)acrylate, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, ethanediol di(meth)acrylate, propanediol di(meth)acrylate, butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, Acrylate, dipropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl maleate, diethyl maleate, dibutyl maleate, methacrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-propyl(meth)acrylamide Examples of the vinyl esters include methyl vinyl benzoate, vinyl benzyl acetate, hydroxystyrene, vinyl acetate, vinyl propionate, vinyl caproate, methyl maleimide, ethyl maleimide, isopropyl maleimide, monomethyl itaconate, dimethyl itaconate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, dibutyl itaconate, methyl crotonate, ethyl crotonate, butyl crotonate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, and dibutyl phthalate. These may be used alone or in combination of two or more.

[0028] [Average particle size of polymer (a11)] The average particle size of the polymer (a11) in the latex (A1) is from 0.30 to 5.00 μm, preferably from 0.50 to 3.00 μm, and more preferably from 0.60 to 2.00 μm. The method for adjusting the average particle size within the above range is not particularly limited, but examples thereof include, and are preferred, a method in which, when obtaining a polymer (a11) of an ethylenically unsaturated monomer by emulsion polymerization, a method in which a divalent or higher salt such as a magnesium salt or an aluminum salt is allowed to coexist during polymerization, and a method in which the emulsifier concentration during polymerization is initially low and gradually increased during dropwise addition of the monomer emulsion.

[0029] When the average particle size of the polymer (a11) is 0.3 μm or more, the specific surface area is relatively small, so that the crystallization of the chloroprene polymer is less inhibited when mixed with the chloroprene polymer latex (B), resulting in high initial adhesive strength and contact strength. When the average particle size of the polymer (a11) is 5.0 μm or less, the fine particles of the polymer (a11) are less likely to settle, improving the storage stability of the latex (A1). The average particle size is the value at a cumulative frequency of 50% measured using a Microtrac "Nanotrac Wave II."

[0030] 1-2. Surfactants (a12) The surfactant (a12) contained in the latex (A1) for an adhesive composition of the present invention acts as an emulsifier. As the surfactant, commercially available anionic surfactants, nonionic surfactants, and cationic surfactants can be used. Some surfactants have an ethylenically unsaturated bond and become structural units of polymer (a11) through polymerization, but the surfactants that have undergone polymerization do not become surfactant (a12) in the present invention. However, even if a surfactant has an ethylenically unsaturated bond, the surfactant remaining after synthesis of polymer (a11) becomes surfactant (a12) in the present invention. These surfactants can be used alone or in combination of two or more.

[0031] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. Examples of cationic surfactants include ceciltrimethylammonium bromide and laurylpyridinium chloride. Examples of the anionic surfactant include alkylbenzene sulfonates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, and fatty acid salts. The amount of the surfactant used is preferably 0.01 to 10.00 parts by mass, more preferably 0.05 to 5.00 parts by mass, and even more preferably 0.10 to 2.50 parts by mass, per 100 parts by mass of the total of the ethylenically unsaturated monomers.

[0032] In addition, water-soluble polymers having nonionic, cationic, or anionic properties, such as water-soluble (meth)acrylic acid resins and water-soluble (meth)acrylic acid ester resins, can also be used as surfactants. Here, water-soluble polymers are defined as molecules having a structure obtained by polymerizing ethylenically unsaturated monomers and that are water-soluble. Water-soluble polymers can be used regardless of their degree of saponification, average degree of polymerization, or whether or not they are modified. From the viewpoints of polymerization stability and product viscosity, the average degree of polymerization is preferably 100 to 5,000, more preferably 200 to 4,000, and even more preferably 200 to 2,400. From the viewpoint of polymerization stability, the degree of saponification is preferably 50% to 100%, more preferably 60% to 100%, and even more preferably 80% to 100%.

[0033] When the surfactant used is a water-soluble polymer, the amount used is not particularly limited, but from the viewpoint of polymerization stability, it is preferably 1 to 100 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of the total of the ethylenically unsaturated monomers.

[0034] The surfactant (a12) preferably includes an anionic surfactant, more preferably a surfactant represented by the following general formula (1): [ka] (wherein R represents a hydrocarbon skeleton containing at least one selected from the group consisting of a saturated or unsaturated aliphatic skeleton having an average of 5 to 20 carbon atoms, a saturated or unsaturated alicyclic skeleton having an average of 5 to 20 carbon atoms, and an aromatic ring skeleton having an average of 1 to 10 ring structures; M represents sodium or ammonium; and n (average value) is 2 to 60). n (average value) is preferably 2 to 30, and R is preferably a hydrocarbon skeleton containing at least one selected from the group consisting of a saturated or unsaturated aliphatic skeleton having an average of 8 to 18 carbon atoms, and an aromatic ring skeleton having an average of 1 to 5 ring structures. Specific examples include polyoxyethylene oleyl cetyl ether ammonium sulfate, polyoxyethylene nonylphenyl ether sulfate sodium, and polyoxyethylene styrenated phenyl ether sulfate ammonium. More preferably, M is an ammonium surfactant. The surfactant (a12) may be added and mixed after the production of the latex.

[0035] 1-3.Aqueous medium The polymer (a11) of this embodiment exists as a latex (A1). The dispersion medium is an aqueous medium containing water as an essential component. The aqueous medium may contain a hydrophilic solvent in addition to water. The hydrophilic solvent is not particularly limited as long as it is a water-soluble solvent that functions as a medium for dispersing the polymer (a11). Examples of the hydrophilic solvent include alcohols such as methyl alcohol, ethanol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, and benzyl alcohol, and nitrogen-containing organic solvents such as N-methylpyrrolidone, which can be used alone or in combination of two or more.

[0036] The content of the hydrophilic solvent in the aqueous medium is preferably 10% by mass or less, more preferably 5% by mass or less. When the latex (A1) is used as an adhesive, the aqueous medium is preferably water alone. The content of the aqueous medium is preferably in the range of 10 to 70 mass %, more preferably 15 to 65 mass %, and even more preferably 20 to 60 mass % so that the solid content concentration of the latex (A1) is in the range of 10 to 70 mass %, more preferably 15 to 65 mass %, and even more preferably 20 to 60 mass %. When the solid content concentration of the latex (A1) is 70 mass % or less, the storage stability is high. When the solid content concentration of the latex (A1) is 10 mass % or more, the latex (A1) can be processed according to the application and is practical.

[0037] 2. Embodiment 2 of Latex (A) for Adhesive Composition Another embodiment (embodiment 2) of the latex for adhesive compositions (A2) will be described below, but a description of the contents common to embodiment 1 above will be omitted.

[0038] The latex (A2) for an adhesive composition according to the second aspect includes a polymer (a21) of an ethylenically unsaturated monomer, a surfactant (a22), and an aqueous medium, and the polymer (a21) of the ethylenically unsaturated monomer has a carboxy group and a crosslinked structure.

[0039] The polymer (a21) of an ethylenically unsaturated monomer has a carboxy group and a crosslinked structure, and when the adhesive composition of the present invention in which the latex (A2) and the chloroprene polymer latex (B) are mixed is used, the carboxy group promotes gelation of the chloroprene polymer, thereby enabling excellent initial adhesive strength and contact properties to be exhibited.

[0040] It is known that gelation of the chloroprene polymer latex (B) is promoted as the pH decreases, followed by crystallization of the chloroprene polymer, resulting in the development of initial adhesive strength. When the latex (A2) has a carboxy group, which is a weak acid, the adhesive composition obtained by mixing the latex (A2) and the chloroprene polymer latex (B) does not gel during storage and has good storage stability. On the other hand, when the adhesive composition of the present invention is used, the pH in the system is lowered because the water-containing dispersion medium is removed, and the gelation of the chloroprene polymer proceeds rapidly, thereby developing adhesive strength.

[0041] The number of moles of carboxy groups contained per kg of solid content in latex (A2) is preferably 0.01 to 1.00 mol, more preferably 0.05 to 0.50 mol, and even more preferably 0.10 to 0.40 mol. When the number of moles of carboxy groups contained per kg of solid content in latex (A2) is 0.01 mol or more, excellent initial adhesive strength and contact property can be exhibited when mixed with chloroprene polymer latex (B) (described later), and when the number of moles of carboxy groups contained per kg of solid content in latex (A2) is 1.00 mol or less, storage stability is improved when mixed with chloroprene polymer latex (B).

[0042] 2-1. Polymer of ethylenically unsaturated monomer (a21) The structural unit constituting the polymer (a21) of an ethylenically unsaturated monomer is not particularly limited as long as it is a monomer having an ethylenically unsaturated bond. Examples of monomers having an ethylenically unsaturated bond include (meth)acrylic acid, fumaric acid, maleic acid and their esters; (meth)acrylamide and its derivatives; styrene and its derivatives; vinyl esters; N-substituted maleimide compounds; itaconic acid, crotonic acid, phthalic acid and their esters, as well as their metal salts and ammonium salts. The monomers having an ethylenically unsaturated bond can be used alone or in combination of two or more.

[0043] 2-1-1. Ethylenically unsaturated monomers having a carboxy group To introduce a carboxy group into the polymer (a21) of an ethylenically unsaturated monomer, it is preferable to use an ethylenically unsaturated monomer having a carboxy group as a monomer. Examples of the ethylenically unsaturated monomer having a carboxy group are the same as those in the above-mentioned embodiment 1. In this embodiment 2, it is preferable to use an ethylenically unsaturated monomer having two or more carboxy groups in the molecule as a monomer for the polymer (a21) of an ethylenically unsaturated monomer, and it is also possible to use an ethylenically unsaturated monomer having three or more carboxy groups in the molecule, such as aconitic acid.

[0044] The total amount of structural units derived from ethylenically unsaturated monomers having a carboxy group is preferably 0.5 to 5.0 mass% and more preferably 1.0 to 4.0 mass% based on the total amount of structural units derived from all ethylenically unsaturated monomers constituting polymer (a21), for the reasons explained in embodiment 1. More preferably, ethylenically unsaturated monomers having two or more carboxy groups in the molecule are contained in an amount of 1.0 to 4.0 mass% based on the total amount of structural units derived from all ethylenically unsaturated monomers constituting polymer (a21).

[0045] 2-1-2. Crosslinkable ethylenically unsaturated monomers The polymer (a21) of an ethylenically unsaturated monomer has a crosslinked structure, which increases the strength of the adhesive after gelation and allows it to exhibit excellent initial adhesive strength and contact properties. In order to introduce a crosslinked structure into the polymer (a21), it is preferable to use a crosslinkable ethylenically unsaturated monomer as the monomer.

[0046] The crosslinkable ethylenically unsaturated monomer is a compound having a plurality of ethylenically unsaturated bonds in which the crosslinkable ethylenically unsaturated monomers react with each other, or a compound having an ethylenically unsaturated bond and a functional group reactive with a carboxy group. Examples of the compound having a functional group reactive with a carboxy group include ethylenically unsaturated monomers having an epoxy group, such as glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate. Examples of crosslinkable ethylenically unsaturated monomers that react with each other include silane coupling agents having an ethylenically unsaturated group, such as vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropyltriethoxysilane; ethanediol di(meth)acrylate, propanediol di(meth)acrylate, butadiene dimethacrylate, and the like. and monomers containing two or more ethylenically unsaturated groups such as hexanediol di(meth)acrylate, hexanediol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, pentaerythritol tetra(meth)acrylate, and divinylbenzene. Among these, it is more preferable that the crosslinkable ethylenically unsaturated monomer includes at least one selected from the group consisting of ethylenically unsaturated monomers having epoxy groups, silane coupling agents having ethylenically unsaturated groups, and monomers containing two or more ethylenically unsaturated groups.

[0047] The content of the structural units derived from the crosslinkable ethylenically unsaturated monomer is preferably 0.01% by mass or more, and more preferably 0.10% by mass or more, based on the total amount of structural units derived from all ethylenically unsaturated monomers constituting the polymer (a21), because this increases the strength after gelation of the adhesive composition mixed with the chloroprene polymer latex (B) described below, and improves contact properties.

[0048] The content of the structural units derived from the crosslinkable ethylenically unsaturated monomer is preferably 5.00% by mass or less, and more preferably 3.00% by mass or less, based on the total amount of structural units derived from all ethylenically unsaturated monomers constituting the polymer (a21), because this improves the storage stability of the adhesive composition mixed with the chloroprene polymer latex (B).

[0049] 2-1-3. Ethylenically unsaturated monomers having a hydroxyl group The monomers constituting polymer (a1) may include, and preferably include, an ethylenically unsaturated monomer having a hydroxyl group in addition to an ethylenically unsaturated monomer having a carboxyl group and a crosslinkable ethylenically unsaturated monomer. Note that a monomer having a hydrophilic functional group other than a hydroxyl group is referred to as a "surfactant having an ethylenically unsaturated bond" rather than an "ethylenically unsaturated monomer having a hydroxyl group."

[0050] Examples of ethylenically unsaturated monomers having a hydroxyl group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, ethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polyethylene glycol polytetramethylene glycol mono(meth)acrylate, polypropylene glycol polytetramethylene glycol mono(meth)acrylate, etc. The ethylenically unsaturated monomers having a hydroxyl group can be used alone or in combination of two or more.

[0051] The content of the ethylenically unsaturated monomer having a hydroxyl group relative to the total amount of structural units derived from all ethylenically unsaturated monomers constituting the polymer (a21) is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, because this increases the rate of gelation of the adhesive composition mixed with the chloroprene polymer latex (B) described below, thereby improving contact properties.

[0052] The content of the ethylenically unsaturated monomer having a hydroxyl group relative to the total amount of structural units derived from all ethylenically unsaturated monomers constituting the polymer (a21) is preferably 20.0 mass% or less, more preferably 15.0 mass% or less, because this improves the storage stability of the adhesive composition mixed with the chloroprene polymer latex (B).

[0053] 2-1-4. Hydrophobic ethylenically unsaturated monomers The monomers constituting polymer (a21) may include, and preferably include, a hydrophobic ethylenically unsaturated monomer in addition to the carboxyl-containing ethylenically unsaturated monomer, the crosslinkable ethylenically unsaturated monomer, and the hydroxyl-containing ethylenically unsaturated monomer. The hydrophobic ethylenically unsaturated monomer is as described in embodiment 1.

[0054] The acrylic acid polymer (a21) preferably contains 50.0 to 99.4 mass% of hydrophobic ethylenically unsaturated monomers, more preferably 50.0 to 98.0 mass% of hydrophobic ethylenically unsaturated monomers, of all ethylenically unsaturated monomers. When the hydrophobic ethylenically unsaturated monomers account for 50.0 mass% or more of all ethylenically unsaturated monomers, the storage stability of an adhesive composition mixed with a chloroprene polymer latex (B) described below is improved. On the other hand, when the hydrophobic ethylenically unsaturated monomers account for 99.4 mass% or less of all ethylenically unsaturated monomers, the gelation rate of the adhesive composition mixed with a chloroprene polymer latex (B) is increased, and the contact property is improved.

[0055] 2-1-5. Surfactants with ethylenically unsaturated bonds The polymer (a21) of an ethylenically unsaturated monomer preferably contains a structural unit derived from a surfactant having an ethylenically unsaturated bond. This is because the dispersion stability of the particles is improved. Ethylenically unsaturated monomers having a carboxy group are not included in the surfactants having an ethylenically unsaturated bond. Examples of surfactants having an ethylenically unsaturated bond include the compounds represented by chemical formulas (2) to (5) described in embodiment 1.

[0056] 2-1-6. Other ethylenically unsaturated monomers The ethylenically unsaturated monomer in this embodiment can include an ethylenically unsaturated monomer other than an ethylenically unsaturated monomer having a carboxy group, a hydrophobic ethylenically unsaturated monomer, a crosslinkable ethylenically unsaturated monomer, and an ethylenically unsaturated monomer having a hydroxyl group. Specifically, ethylene glycol di(meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, ethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polyethylene glycol polytetramethylene glycol mono(meth)acrylate, polypropylene glycol polytetramethylene glycol mono(meth)acrylate, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, ethanediol di(meth)acrylate, acrylate, propanediol di(meth)acrylate, butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, pentaerythritol tetra(meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl maleate, diethyl maleate, dibutyl maleate, methacrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-propyl (meth)acrylamide, methyl vinyl benzoate, vinyl benzyl acetate, hydroxystyrene, vinyl acetate;Examples of the vinyl acrylate include vinyl propionate, vinyl caproate, methylmaleimide, ethylmaleimide, isopropylmaleimide, monomethyl itaconate, dimethyl itaconate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, dibutyl itaconate, methyl crotonate, ethyl crotonate, butyl crotonate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, and dibutyl phthalate. These may be used alone or in combination of two or more.

[0057] [Average particle size of polymer (a21)] The average particle size of the polymer (a21) in the latex (A2) is preferably 0.30 to 5.00 μm, more preferably 0.50 to 3.00 μm, and even more preferably 0.60 to 2.00 μm. The method for adjusting the average particle size to the above range, the reason for setting the average particle size within the above range, and the definition of the average particle size are as explained for the polymer (a11) in embodiment 1.

[0058] 2-2. Surfactant (a22) and aqueous medium The surfactant (a22) and the aqueous medium are the same as those described for the surfactant (a12) in embodiment 1.

[0059] 3. Method for producing latex (A) for adhesive composition The latex (A) for an adhesive composition of the present invention can be produced by a known polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization, or bulk polymerization using an ethylenically unsaturated monomer for synthesizing the polymer (a1), a surfactant (a2), and an aqueous medium. It can also be produced by a continuous polymerization method or a batch polymerization method. Among these, from the viewpoint of particle size uniformity, production by suspension polymerization or emulsion polymerization is preferred, and production by emulsion polymerization is more preferred.

[0060] The emulsion polymerization method may be, for example, a method in which the above-mentioned components are charged all at once and polymerized, or a method in which the components are polymerized while being continuously supplied. As a method in which the components are polymerized while being continuously supplied, for example, a method in which a mixed emulsion obtained by mixing and emulsifying an ethylenically unsaturated monomer, an aqueous medium, and a surfactant into a polymerization initiator solution obtained by mixing a part of the polymerization initiator, an aqueous medium, and a surfactant, and the remainder of the polymerization initiator are continuously supplied and stirred.

[0061] It is preferable to use a polymerization initiator when carrying out emulsion polymerization. Examples of polymerization initiators that can be used include well-known and commonly used persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, azo compounds, and organic peroxides. Redox initiators, which are combinations of these polymerization initiators with reducing agents, may also be used. To ensure an appropriate polymerization rate, the amount of polymerization initiator used is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.8 parts by mass, and even more preferably 0.1 to 0.5 parts by mass, per 100 parts by mass of the total ethylenically unsaturated monomers.

[0062] The temperature during emulsion polymerization varies depending on the type of polymerization initiator, but can be, for example, 30 to 85°C. When obtaining the polymer (a1), a chain transfer agent such as mercaptan, thioglycolic acid and its esters, β-mercaptopropionic acid and its esters, etc. may be used to adjust the molecular weight.

[0063] 4. pH of latex (A) for adhesive composition It is possible and preferable to adjust the pH after obtaining the polymer (a1). In this case, the degree of neutralization of the latex (A) is preferably 0.3 or more, more preferably 0.5 or more. Furthermore, the degree of neutralization of the latex (A) is preferably 0.7 to 1.3, more preferably 0.8 to 1.2, and even more preferably 0.9 to 1.1. The degree of neutralization of the latex (A) is the ratio of the amount of the basic compound added to the amount of the basic compound required to neutralize the carboxyl groups and other acidic components contained in the latex (A).

[0064] When the degree of neutralization of the latex (A) is 0.3 or more, the storage stability of the adhesive composition obtained by mixing the latex (A) and the chloroprene polymer latex (B) is improved.When the degree of neutralization of the latex is 1.3 or less, the gelation of the adhesive composition obtained by mixing the latex (A) and the chloroprene polymer latex (B) proceeds quickly, and sufficient contact properties are obtained.

[0065] The pH of the latex (A) at 25° C. is preferably 6.0 to 10.0, more preferably 6.5 to 9.5, and even more preferably 7.0 to 9.5. If the pH is 6 or higher, the storage stability of the adhesive composition obtained by mixing the latex (A) and the chloroprene polymer latex (B) is improved, and if the pH is 10 or lower, the gelation of the adhesive composition obtained by mixing the latex (A) and the chloroprene polymer latex (B) progresses quickly, and sufficient contact strength is obtained. The basic compound added for neutralization is not particularly limited, but examples include sodium hydroxide, potassium hydroxide, aqueous ammonia, etc. In particular, from the viewpoint of storage stability, it is preferable to add aqueous ammonia.

[0066] 5. Formaldehyde emission amount of latex (A) for adhesive composition The latex (A) of the present invention preferably has a formaldehyde emission amount of 0.05 mg / L or less when measured using a test piece prepared in accordance with JIS A 1902-2 by the glass desiccator method in accordance with JIS A 1460. There are no particular limitations on the method for adjusting the formaldehyde content to this range, but it can be achieved, for example, by not using formaldehyde or a material derived from formaldehyde as a raw material of the adhesive composition.

[0067] 6. Chloroprene polymer latex (B) The chloroprene polymer latex (B) according to this embodiment is a latex in which a chloroprene polymer is dispersed as fine particles in an aqueous solvent. The chloroprene polymer constituting the chloroprene polymer latex (B) is a chloroprene homopolymer or a copolymer of chloroprene and a monomer copolymerizable with chloroprene. That is, the chloroprene polymer is a polymer containing structural units derived from chloroprene. Examples of copolymerizable monomers include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, and methacrylic acid and its esters. Structural units derived from other copolymerizable monomers are contained in the chloroprene copolymer to the extent that they do not impair the performance desired by the present invention. In the chloroprene polymer, the content of structural units derived from chloroprene is 80 mol % or more.

[0068] Specific examples of the copolymerizable monomer include copolymers containing 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid esters, and methacrylic acid esters in the range of 0.01 to 20% by mass, and acrylic acid and methacrylic acid in the range of 0.01 to 7% by mass. Two or more types of monomers constituting the copolymer may be used as needed. Two or more types of polymers may also be mixed and used. When other copolymerizable monomers are used in combination with chloroprene, the adhesive composition exhibits good contact properties and initial adhesive strength if the content of the other copolymerizable monomer units in the copolymer is 20 mol % or less.

[0069] The surfactant for the chloroprene polymer latex (B) is not particularly limited, and those listed in (a2) can be used. Among these, anionic surfactants are preferred. In particular, anionic surfactants having a carboxy group are more preferred, as they can exhibit excellent initial adhesive strength and contact properties when mixed with the latex (A). In particular, surfactants that become insoluble when the pH drops below a certain level are preferred, and among these, those stabilized with an alkali salt of a rosin acid containing abietic acid as the main component are more preferred. The anionic surfactant having a carboxy group may be introduced as an emulsifier during polymerization of the chloroprene polymer latex, or may be added as an additive after polymerization.

[0070] The amount of surfactant contained in the chloroprene polymer latex (B) is preferably 1 to 8 mass% and more preferably 2 to 5 mass% based on the solid content of the chloroprene polymer latex (B). When the amount of surfactant is 1 mass% or more based on the solid content of the chloroprene polymer latex (B), sufficient stability is achieved during polymerization and storage. When the amount is 8 mass% or less, the adhesive composition has good contact properties and initial adhesive strength.

[0071] 7. Mixing ratio of latex (A) for adhesive composition to chloroprene copolymer (B) The mixing ratio by mass of the latex (A) to the chloroprene polymer latex (B) in the adhesive composition of the present invention is preferably 1:99 to 99:1 in terms of solid content, more preferably 10:90 to 90:10, and even more preferably 25:75 to 70:30. Since the initial adhesive strength and contact properties of the adhesive composition of the present invention depend on the crystallization of the chloroprene polymer, a solid content ratio of 1:99 or more ensures that the initial adhesive strength and contact properties are exhibited, while a solid content ratio of 99:1 or less accelerates the gelation of the adhesive composition, resulting in sufficient contact properties.

[0072] The method for mixing the latex (A) and the chloroprene polymer latex (B) is not particularly limited, and examples thereof include manual mixing, a rotary tooth type agitator such as a disper, a high-pressure type, an ultrasonic type, a high-speed rotation type homogenizer, etc. In any method, it is preferable not to apply excessive shear force from the viewpoint of suppressing the generation of aggregates during mixing.

[0073] The pH of the adhesive composition of the present invention is preferably in the range of 5.0 to 12.0, more preferably 6.0 to 11.0, and even more preferably 7.0 to 10.0. If the pH of the adhesive composition is 5.0 or higher, the storage stability of the adhesive composition is improved, and if the pH is 12.0 or lower, the gelation of the adhesive composition proceeds quickly, and sufficient contact properties are obtained.

[0074] 8. Additives The adhesive composition of the present invention may contain optional additives described below in addition to the latex (A) and the chloroprene polymer latex (B). These additives can be added when mixing the latex (A) and the latex (B). Alternatively, the adhesive composition may be produced by adding the additives to the latex (A) and / or the latex (B) in advance, provided that the effects of the present invention are not impaired.

[0075] 8-1. pH adjuster The adhesive composition of the present invention can be adjusted to a desired pH using a pH adjuster, which may include common acidic substances such as inorganic acids and organic acids, their salts, and amphoteric salts of amino acids, as well as various latexes with a pH of 10 or less.

[0076] Examples of pH adjusters include organic acids such as acetic acid, formic acid, glycolic acid, malic acid, citric acid, maleic acid, fumaric acid, malonic acid, phthalic acid, isophthalic acid, lactic acid, butyric acid, ascorbic acid, succinic acid, tartaric acid, acrylic acid, methacrylic acid, crotonic acid, adipic acid, oxalic acid, and abietic acid. Examples of inorganic acids include boric acid, phosphoric acid, hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, and sulfurous acid. Further examples include salts of organic or inorganic acids with sodium, potassium, ammonia, aminoethanol, diethanolamine, and triethanolamine.

[0077] Examples of the amino acid include glycine, glycylglycine, asparagine, aspartic acid, alanine, phenylalanine, arginine, glutamine, glutamic acid, etc. Examples of the latex having a pH of 10 or less include, in addition to the latex (A), copolymer latexes of acrylic acid esters or methacrylic acid esters, styrene-butadiene copolymers copolymerized with acrylic acid, methacrylic acid, etc., and carboxyl-modified synthetic rubber latexes such as chloroprene, but are not particularly limited thereto. The pH adjuster can be used alone or in combination of two or more. From the viewpoint of the initial adhesiveness, contact strength, and storage stability of the adhesive composition, amino acids such as glycine, alanine, phenylalanine, and glutamic acid, and organic acids such as malonic acid are preferred.

[0078] 8-2. Tackifying resin The adhesive composition of the present invention may contain a tackifying resin. Specific examples include rosin resins, rosin ester resins, hydrogenated rosin resins, polymerized rosin resins, α-pinene resins, β-pinene resins, terpene phenol resins, C5 fraction petroleum resins, C9 fraction petroleum resins, C5 fraction / C9 fraction petroleum resins, dicyclopentadiene petroleum resins, alkylphenol resins, xylene resins, coumarone resins, and coumarone-indene resins. The tackifying resins may be used alone or in combination of two or more. The tackifying resin is preferably added as a latex to ensure uniform dispersion in the adhesive composition.

[0079] 8-3.Plasticizers The adhesive composition of the present invention may contain a plasticizer. Among them, dibasic acid ester plasticizers are preferred. Specific examples of dibasic acid ester plasticizers include dialkyl phthalates, dialkyl adipates, and dialkyl sebacates. The content of the dibasic acid ester plasticizer is preferably 10 parts by mass or less based on the total solid content of the latex (A) and the latex (B).

[0080] 8-4. Antioxidants The adhesive composition of the present invention may contain an antioxidant. Examples of antioxidants include hindered phenol-based antioxidants. Specific examples include 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), and butylated reaction products of p-cresol and dicyclopentadiene. The amount of antioxidant added is preferably 0.1 to 3 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the solid content of latex (A) and latex (B). When the amount of antioxidant added is 0.1 part by mass or more, sufficient antioxidant effect can be obtained, and when it is 3 parts by mass or less, sufficient initial adhesive strength and contact strength can be obtained.

[0081] 8-5. Other additives In addition to the above additives, fillers, pigments, colorants, wetting agents, antifoaming agents, thickeners, and the like may be appropriately used in the adhesive composition of the present invention, as long as the effects of the present invention are not impaired. Furthermore, other resin-based polymer latexes may be blended supplementarily in an amount up to 10% by mass (solid content equivalent) of the adhesive composition, specifically latexes of polymers composed of the group listed as ethylenically unsaturated monomers constituting polymer (a1).

[0082] 9. Method of using the adhesive composition The method for applying the adhesive composition of the present invention is not particularly limited, but examples thereof include dipping, brush coating, spraying, line coating, etc. The application conditions such as the amount applied and drying time are also not particularly limited, but for example, the amount applied to the adherend is 10 to 500 g / m 2 The adhesive composition is applied under these conditions, left to stand for 1 minute to 1 hour at 5 to 40°C, then attached to another adherend and pressed with both hands for 1 to 30 seconds, thereby obtaining sufficient initial adhesive strength and contact strength. Alternatively, in this step, the adhesive composition may be applied to the adherend and then immediately attached to the other adherend.

[0083] The adhesive composition of the present invention can be suitably used as a one-component aqueous adhesive. It is particularly useful when at least one of the two adherends to be bonded is a porous or water-absorbent material. Examples of porous materials include foams made from materials such as polyurethane, ethylene-vinyl acetate copolymer, and polyethylene, while examples of water-absorbent materials include wood, cloth, and textiles. Members in which porous materials are bonded together can be used as cushioning materials or building materials for furniture, automotive interiors, and construction. [Example]

[0084] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0085] [Measurement method] <ph> The pH was measured at 25°C using "HM-30G" manufactured by Toa DKK Corporation. <Average particle size> The average particle size was measured using a Nanotrac (registered trademark) Wave II manufactured by Microtrac, and the value at a cumulative frequency of 50% was taken as the average particle size.

[0086] <Formaldehyde emission amount> According to JIS A 1902-2, 13.5 g of latex (A) was applied to a 15 cm × 30 cm glass plate and cured at 23°C for 24 hours to prepare a test piece. Using the test piece, measurements were performed by the glass desiccator method according to JIS A 1460.

[0087] <Contactability> One side of a polyurethane foam cube with sides of 5 cm was sprayed with a spray gun W-101-131G manufactured by Anest Iwata Corporation, using an air pressure of 0.4 MPa, a latex spray volume of 120 ml / min, a spray distance of 30 cm, and a coating amount of 100 g / m. 2 The adhesive composition was applied under the conditions and left at 25°C for 1 minute. The coated surfaces were pinched with the fingers along the center line at the crease and bonded together for 5 seconds, after which the surfaces were visually inspected to see if the polyurethane foam peeled off and would not return to its original state even when the fingers were removed. If the polyurethane foam peeled off, the process of pinching the coated surfaces along the center line at the crease and bonding them together for 5 seconds was immediately repeated, and the number of times the polyurethane foam was bonded until it was adhered and would not peel off was evaluated. The fewer the number of times, the better the contact property. Five samples were evaluated, and the average value was used as the contact property evaluation value.

[0088] <Initial adhesive strength> Two 5cm square, 2.5cm thick polyurethane foam substrates were prepared, and one surface of each was sprayed with a spray gun W-101-131G manufactured by Anest Iwata Corporation at an air pressure of 0.4MPa, a latex spray volume of 120ml / min, a spray distance of 30cm, and a coating amount of 100g / m. 2 The adhesive composition was applied under these conditions, left for 1 minute at 25°C, and then the 2.5 cm x 5 cm adhesive surfaces were bonded together and pressed together with both hands for 5 seconds. After pressing, both ends of the test piece were left for 30 seconds or 2 minutes, and then clamped between the chucks of an Autograph (registered trademark) AG-X (manufactured by Shimadzu Corporation) and pulled at a pulling rate of 200 mm / min in an atmosphere of 23°C and 50% RH to measure the adhesive strength.

[0089] <Storage stability> The adhesive composition was sealed in a glass bottle and left at 70°C for 7 days, and the viscosity was measured before and after the storage to evaluate storage stability. The viscosity was measured at 23°C using a BL-type viscometer with a No. 19 rotor at 60 rpm.

[0090] [Production of latex (A)] Synthesis example 1: 12.4 g of methacrylic acid, 84.6 g of methyl methacrylate, 384.6 g of 2-ethylhexyl acrylate, 8.7 g of 2-hydroxyethyl acrylate, 0.9 g of glycidyl methacrylate, 1.78 g of Hitenol 08E, 4.2 g of Eleminol JS-20, and 130 g of ion-exchanged water were uniformly emulsified using a homogenizer to obtain a monomer emulsion. 125 g of ion-exchanged water, 0.32 g of Hitenol® 08E (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene oleyl cetyl ether ammonium sulfate, solids concentration 100% by mass), 0.3 g of Eleminol® JS-20 (manufactured by Sanyo Chemical Industries, Ltd., sodium alkylaryl sulfosuccinate, solids concentration 40% by mass), 0.6 g of magnesium nitrate, and 1.7 g of 2-ethylhexyl thioglycolate were placed in a 1 L five-neck separable flask and heated to 80°C with stirring. 0.25 g of potassium persulfate (5% by mass of the monomer emulsion) was added to the separable flask, and the remaining monomer emulsion was then added dropwise to initiate the reaction. The monomer emulsion was added to the separable flask over 4 hours, and simultaneously, an aqueous solution prepared by dissolving 1.65 g of potassium persulfate in 60 g of ion-exchanged water was added over 4.5 hours. After the addition of the aqueous potassium persulfate solution was completed, the mixture was stirred at 80°C for 1 hour to terminate the reaction. The separable flask was cooled, and 9.8 g of 25% by mass ammonia water was added to neutralize the system. 173.1 g of ion-exchanged water was then added to dilute the mixture to a solids content of 50% by mass, yielding latex (A-1). Its composition, average particle size, pH, and formaldehyde emission are shown in Table 1.

[0091] Synthesis examples 2-11: Latexes (A-2) to (A-8) and (X-1) to (X-3) were obtained in the same manner as in Synthesis Example 1, except that the compositions were as shown in Table 1. The compositions, average particle sizes, pH values, and formaldehyde emissions are shown in Table 1.

[0092] The details of each surfactant component in Table 1 are as follows: (1) Trax N-200: manufactured by NOF Corporation, polyoxyethylene nonylphenyl ether sodium sulfate, aqueous solution with a solids concentration of 26% by mass, (2) Hitenol (registered trademark) NF-13: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene styrenated phenyl ether ammonium sulfate, solid content 100% by mass, (3) Adeka Reasoap (registered trademark) SE-11: manufactured by ADEKA Corporation, ammonium salt of α-sulfo-ω-(1-(nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy)poly(oxy-1,2-ethanediyl), solid content 100% by mass, (4) Emulgen (registered trademark) 147: manufactured by Kao Corporation, polyoxyethylene lauryl ether, solid content 100% by mass, (5) Eleminol (registered trademark) RS-3000: manufactured by Sanyo Chemical Industries, Ltd., an aqueous solution of methacryloyloxypolyoxypropylene sulfate sodium salt, with a solid content of 50% by mass, (6) Hitenol (registered trademark) 08E: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene oleyl cetyl ether ammonium sulfate, solid content concentration 100% by mass, (7) Hitenol (registered trademark) NF-13: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyethylene styrenated phenyl ether ammonium sulfate, solid content 100% by mass, (8) Eleminol (registered trademark) JS-20: (manufactured by Sanyo Chemical Industries, Ltd., sodium alkylaryl sulfosuccinate, solid content concentration 40 mass%.

[0093] [Production of adhesive composition] Example 1: 31.8 g of Shopren (registered trademark) SD130 (a chloroprene homopolymer latex manufactured by Showa Denko K.K., containing sodium rosinate and potassium rosinate, with a surfactant concentration of 2% by mass relative to the solid content and a solid content of 55% by mass) was mixed as latex (B-1), 35 g of latex (A-1), and 0.3 g of glycine as a pH adjuster to obtain composition 1. The composition and evaluation results are shown in Tables 2 and 3.

[0094] Examples 2 to 15 and Comparative Examples 1 to 6: Compositions 2 to 21 were obtained by the same production method as in Example 1, except that the compositions were as shown in Tables 2 and 3. The compositions and evaluation results are shown in Tables 2 and 3. The details of each component in Tables 2 and 3 are as follows: Showpren (registered trademark) SD77S: chloroprene polymer latex manufactured by Showa Denko K.K., containing sodium rosinate and potassium rosinate, solid content 55% by mass, surfactant concentration relative to solid content 2% by mass

[0095] [Table 1]

[0096] [Table 2]

[0097] [Table 3]

[0098] The results in Tables 2 and 3 show that the adhesive compositions of the present invention (Examples 1 to 15) exhibit excellent contact properties and initial adhesive strength, i.e., they can obtain strong adhesive strength in a short time. On the other hand, the adhesive compositions containing latexes with an average particle size of less than 0.3 μm (Comparative Examples 1 to 4) were found to be inferior in contact properties and initial adhesive strength. Furthermore, it was found that latex (A) or latex (B) alone did not exhibit contact properties and had extremely low initial adhesive strength (Comparative Examples 5 and 6).

[0099] Preparation of latex (A): The components used in Synthesis Examples 101 to 111 are as follows.

[0100] [Ethylenically unsaturated monomers constituting polymer (a1)] (1) Methacrylic acid: manufactured by Nippon Shokubai Co., Ltd. (2) Itaconic acid: manufactured by Fuso Chemical Co., Ltd. (3) Aconitic acid: manufactured by Tokyo Chemical Industry Co., Ltd.

[0101] (4) Styrene: manufactured by Idemitsu Kosan Co., Ltd. (5) Methyl methacrylate: manufactured by Mitsubishi Rayon Co., Ltd. (6) 2-Ethylhexyl acrylate: manufactured by Nippon Shokubai Co., Ltd. (7) 2-hydroxyethyl acrylate: manufactured by Kyoeisha Chemical Co., Ltd.

[0102] (8) Glycidyl methacrylate: manufactured by The Dow Chemical Company, (9) Methacryloyloxytrimethoxysilane: manufactured by Shin-Etsu Silicone Co., Ltd. (10) Divinylbenzene: manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

[0103] [Surfactants] (1) Hitenol (registered trademark) 08E: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene oleyl cetyl ether ammonium sulfate, solid content concentration 100% by mass, (2) Hitenol (registered trademark) NF-13: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene styrenated phenyl ether ammonium sulfate, solid content 100% by mass, (3) Eleminol (registered trademark) JS-20: (manufactured by Sanyo Chemical Industries, Ltd., sodium alkylaryl sulfosuccinate, solid content concentration 40 mass %)

[0104] [Other ingredients] (1) Magnesium nitrate: manufactured by Ako Kasei Co., Ltd. (2) 2-Ethylhexyl thioglycolate: manufactured by Daicel Corporation (3) Potassium persulfate: manufactured by ADEKA Corporation (4) 25% ammonia water (5) Potassium hydroxide: manufactured by Osaka Soda Co., Ltd.

[0105] Synthesis Example 101: 12.4 g of methacrylic acid, 84.6 g of methyl methacrylate, 384.8 g of 2-ethylhexyl acrylate, 8.7 g of 2-hydroxyethyl acrylate, 0.9 g of glycidyl methacrylate, 1.78 g of Hitenol 08E, 4.2 g of Eleminol JS-20, and 130 g of ion-exchanged water were uniformly emulsified using a homogenizer to obtain a monomer emulsion. 125 g of ion-exchanged water, 0.32 g of Hitenol 08E, 0.3 g of Eleminol JS-20, 0.6 g of magnesium nitrate, and 1.7 g of 2-ethylhexyl thioglycolate were placed in a 1 L five-neck separable flask and heated to 80 °C with stirring. 0.25 g of potassium persulfate and 5% by mass of the monomer emulsion were added to the separable flask, and the reaction was initiated by starting the dropwise addition of the remaining monomer emulsion. The monomer emulsion was added to the separable flask over 4 hours, while an aqueous solution of 1.65 g of potassium persulfate dissolved in 60 g of ion-exchanged water was also added over 4.5 hours. After the addition of the potassium persulfate aqueous solution was completed, the mixture was stirred at 80 °C for 1 hour to terminate the reaction. The separable flask was cooled, and 9.8 g of 25% by mass ammonia water was added to neutralize the system. Thereafter, 173.1 g of ion-exchanged water was added to dilute the mixture to a solid content of 50% by mass, thereby obtaining latex (A-101). The composition, average particle size, pH, and formaldehyde emission amount of the latex (A-101) are shown in Table 4.

[0106] Synthesis Examples 102-111: Latexes (A-102) to (A-109) and (X-101) to (X-102) were obtained in the same manner as in Synthesis Example 101, except that the compositions were as shown in Table 4. Table 4 shows the compositions, average particle sizes, pH values, and formaldehyde emissions.

[0107] Preparation of the adhesive composition: In the following Examples 101 to 117 and Comparative Examples 101 to 104, A101 to A109 and X-101 to X102 prepared in Synthesis Examples 101 to 111 were used as latexes (A) for adhesive compositions, and the following chloroprene polymer latexes ((B-1), (B-2)) and pH adjusters were used. Chloroprene polymer latex (B-1): Showpren (registered trademark) SD130 (a chloroprene homopolymer latex manufactured by Showa Denko K.K., containing sodium rosinate and potassium rosinate, surfactant concentration relative to solid content: 2% by mass, solid content: 55% by mass) (abbreviated as SD130 in Tables 5 and 6), Chloroprene polymer latex (B-2): Showpren (registered trademark) SD77S, a chloroprene polymer latex manufactured by Showa Denko K.K., containing sodium rosinate and potassium rosinate, solid content 55% by mass, surfactant concentration relative to solid content 2% by mass (abbreviated as SD77S in Tables 5 and 6), pH adjuster: Glycine (Showa Denko K.K.)

[0108] Example 101: 31.8 g of chloroprene polymer latex (B-1), 35 g of latex (A-101), and 0.3 g of glycine as a pH adjuster were mixed to obtain adhesive composition 101. The composition and evaluation results are shown in Tables 5 and 6.

[0109] Examples 102 to 117, Comparative Examples 101 to 104 Adhesive compositions 102 to 121 were obtained in the same manner as in Example 101, except that the compositions were as shown in Tables 5 and 6. The compositions and evaluation results are shown in Tables 5 and 6.

[0110] [Table 4]

[0111] [Table 5]

[0112] [Table 6]

[0113] The results in Tables 5 and 6 indicate that the adhesive compositions of the present invention (Examples 101 to 117) exhibit excellent contact properties and initial adhesive strength, i.e., they can obtain strong adhesive strength in a short time. On the other hand, adhesive composition 118 of Comparative Example 101, which used a latex for adhesive compositions (X-101) that did not contain a structural unit derived from an ethylenically unsaturated monomer having a carboxy group in the polymer (a1), gelled, making it impossible to measure the viscosity, contact properties, and initial adhesive strength. Furthermore, adhesive composition 119 of Comparative Example 102, which used a latex for adhesive compositions (X-102) that did not contain a structural unit derived from a crosslinkable ethylenically unsaturated monomer in the polymer (a1), had high viscosity and insufficient contact properties and initial adhesive strength. It was also found that latex (A) or latex (B) alone did not exhibit contact properties and had extremely low initial adhesive strength (Comparative Examples 103 to 104).< / ph>

Claims

1. A latex (A) for an adhesive composition comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2), an aqueous medium, and a divalent or higher valent salt, wherein the polymer (a1) of the ethylenically unsaturated monomer has a carboxy group, and the average particle size of the polymer (a1) of the ethylenically unsaturated monomer measured with a Nanotrac (registered trademark) Wave II is 0.30 to 5.00 μm; The divalent or higher valent salt is a magnesium salt or an aluminum salt. Latex for adhesive compositions.

2. 2. The latex for an adhesive composition according to claim 1, wherein the polymer (a1) of the ethylenically unsaturated monomer has an average particle size of 0.50 to 3.00 μm.

3. 3. The latex for an adhesive composition according to claim 1 or 2, wherein the polymer (a1) of an ethylenically unsaturated monomer has a structural unit derived from an ethylenically unsaturated monomer having a carboxy group and a structural unit derived from an ethylenically unsaturated monomer having a functional group reactive to a carboxy group.

4. The latex for an adhesive composition according to any one of claims 1 to 3, wherein the polymer (a1) of an ethylenically unsaturated monomer has a structural unit derived from a crosslinkable ethylenically unsaturated monomer having a plurality of ethylenically unsaturated bonds in the molecule.

5. The latex for an adhesive composition according to any one of claims 1 to 4, wherein the polymer (a1) of the ethylenically unsaturated monomer has a crosslinked structure.

6. 6. A latex (A) for an adhesive composition according to any one of claims 1 to 5, comprising a polymer (a1) of an ethylenically unsaturated monomer, a surfactant (a2), and an aqueous medium, wherein the polymer (a1) of the ethylenically unsaturated monomer has a carboxy group and a crosslinked structure. latex.

7. 7. The latex for an adhesive composition according to claim 1, wherein the polymer (a1) of an ethylenically unsaturated monomer contains at least one of a structural unit derived from an ethylenically unsaturated monomer having an epoxy group, a structural unit derived from a silane coupling agent having an ethylenically unsaturated bond, and a structural unit derived from a monomer containing two or more ethylenically unsaturated bonds.

8. The latex for an adhesive composition according to any one of claims 1 to 7, wherein the polymer (a1) of an ethylenically unsaturated monomer contains a structural unit derived from an ethylenically unsaturated monomer having two or more carboxy groups in the molecule.

9. The latex for an adhesive composition according to any one of claims 1 to 8, wherein the polymer (a1) of an ethylenically unsaturated monomer contains a structural unit derived from an ethylenically unsaturated monomer having one or more hydroxyl groups in the molecule.

10. The latex for an adhesive composition according to any one of claims 1 to 9, wherein the polymer (a1) of an ethylenically unsaturated monomer contains at least one of (meth)acrylic acid and itaconic acid as a constituent monomer unit.

11. The surfactant (a2) is represented by the following general formula (1): 【Chemistry 1】 (wherein R represents a hydrocarbon skeleton containing at least one selected from the group consisting of a saturated or unsaturated aliphatic skeleton having an average of 5 to 20 carbon atoms, a saturated or unsaturated alicyclic skeleton having an average of 5 to 20 carbon atoms, and an aromatic ring skeleton having an average of 1 to 10 ring structures; M represents sodium or ammonium; and n (average value) is 2 to 60).

12. 12. The latex for an adhesive composition according to claim 1, wherein the degree of neutralization is 0.3 to 1.

3.

13. An adhesive composition comprising the latex for adhesive compositions (A) according to any one of claims 1 to 12 and a chloroprene polymer latex (B).

14. The adhesive composition according to claim 13, wherein the chloroprene polymer latex (B) contains an anionic surfactant having a carboxy group.

15. The adhesive composition according to claim 13 or 14, wherein a mixing ratio of the latex for adhesive compositions (A) to the chloroprene polymer latex (B) is 10:90 to 90:10 in terms of a mass ratio of solid contents.

16. The adhesive composition according to any one of claims 13 to 15, wherein a mixing ratio of the latex for adhesive compositions (A) to the chloroprene polymer latex (B) is 25:75 to 70:30 in terms of a mass ratio of solid contents.

17. The adhesive composition according to any one of claims 13 to 16, further comprising a pH adjuster.

18. An article in which porous members are bonded to each other, or a porous member and another member, with the adhesive composition according to any one of claims 13 to 17.

19. An article in which water-absorbent members are bonded to each other, or a water-absorbent member and another member, with the adhesive composition according to any one of claims 13 to 17.

20. 20. Furniture or an automobile interior member using the article according to claim 18 or 19 as a cushioning material.

21. 20. A building material comprising in its structure the article of claim 18 or 19.

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