JP6627097B2 - Latex composition and one-part water-based adhesive - Google Patents

Description

The present invention relates to a latex composition having (A) a chloroprene homopolymer latex, (B) a chloroprene copolymer latex, and (C) a pH adjuster, and a one-component aqueous adhesive using the same.

General adhesives are manufactured using vinyl acetate-based polymers, chloroprene-based polymers, acrylate-based polymers, natural rubber, urethane-based polymers, and the like as raw materials. Among them, chloroprene polymers are preferably used for adhesive applications such as solvent-based contact adhesives and graft adhesives because they can provide a high degree of adhesion to a wide range of adherends with low pressure bonding. However, in the case of solvent-based bonding, in addition to the risk of ignition in the work environment and the cost of special exhaust and recovery equipment taken to prevent it, volatile organic compound (VOC) regulations are required due to environmental pollution and human health concerns. And solvent regulations are becoming stricter year by year.
To respond to this regulation, water-based adhesives using chloroprene-based polymer latex have been actively developed in order to eliminate solvents, but water-based adhesives have a higher adhesive strength than conventional solvent-based adhesives. Is low.

Therefore, a two-part adhesive has been studied as a technique for improving the adhesive strength of the adhesive, particularly, the initial adhesive strength. For example, a specific polychloroprene latex is used as a main ingredient in an acrylic latex or SBR-based adhesive. 2. Description of the Related Art Two-part adhesives using a composition containing a specific amount of latex and an anionic surfactant and using a polyvalent metal salt as a curing agent (see Patent Documents 1 and 2) are known.
There is no problem when the two-component adhesive is applied to the adherend with a brush or a roller. However, when these adhesives are applied by spraying, the pot life of the adhesive and the initial adhesive strength are not balanced, the mixing ratio of the adhesive is not stable, the bonding operation is not stable, and the spray is clogged. There are many troubles such as.

In addition, by adding a specific acrylic polymer latex and a specific surfactant to the chloroprene polymer latex, a one-pack type aqueous system having an excellent balance between initial adhesive strength, contact properties, storage stability, and spray application properties. It is known that a chloroprene-based polymer latex composition suitable for use in adhesives can be obtained (see Patent Document 3).

JP-A-56-59874 JP-A-9-188860 Japanese Patent Application No. 2009-271802

The present invention provides a latex composition suitable for use in a one-part aqueous adhesive in which the initial adhesive strength is excellent, the texture of the adhesive layer, the storage stability is excellent, and the adhesive layer after drying is flexible. It is an object to provide a one-component aqueous adhesive used.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, the (A) chloroprene homopolymer latex contains (B) chloroprene copolymer latex and (C) a specific pH adjuster. It has been found that the above problem can be solved.

That is, the present invention relates to (A) a chloroprene homopolymer latex containing a chloroprene homopolymer obtained by emulsion polymerization of chloroprene, 50 to 90% by mass in terms of solid content, (B) chloroprene and 2,3-dichloromethane. Chloroprene copolymer latex containing a chloroprene copolymer obtained by emulsion polymerization of -1,3-butadiene, 100 parts by mass of a latex mixture having a solid content of 10 to 50% by mass (solid content), (C) A latex composition containing 3 to 7 parts by mass (in terms of solid content) of boric acid or at least one pH adjuster selected from amino acids having an isoelectric point of 5.5 to 6.5.

The chloroprene homopolymer has a gel content (toluene-insoluble content) of 30% by mass or less, a number-average molecular weight of the toluene-soluble component of 200,000 to 500,000, and a molecular weight distribution (Mw / Mn) of 2.0 to 4%. .0.

The chloroprene copolymer preferably has a content of a binding unit derived from 2,3-dichloro-1,3-butadiene of 5 to 50% by mass.
The durometer hardness (type A) defined by JIS K 6253-3 of the dried sheet obtained by drying the latex composition is preferably 30 to 70.
The chloroprene homopolymer and the chloroprene copolymer preferably have a monomer polymerization conversion of 65% by mass or more and less than 90% by mass.
The latex composition can be used as a one-part aqueous adhesive.

The latex composition of the present invention, while maintaining the high crystallization rate inherent to chloroprene homopolymer latex, storage stability, without lowering spray coating properties, improving the initial adhesive strength and contact properties. It is useful as a one-component aqueous adhesive composition. In particular, since the adhesive layer after drying is flexible, at least one of the two adherends to be adhered is made of a flexible material, for example, sofas, beds, furniture such as chairs, building materials, plush toys, and the like. It is suitable for one-pack type aqueous adhesive applications for foams (foams) such as toys and automobile interior parts and adherends such as wood, leather or foams.

Hereinafter, the present invention will be described in detail.
The latex composition of the present invention comprises (A) a chloroprene homopolymer latex containing a chloroprene homopolymer obtained by emulsion polymerization of chloroprene, and (B) chloroprene and 2,3-dichloro-1,3-butadiene. A chloroprene copolymer latex containing a chloroprene copolymer obtained by emulsion polymerization, (C) boric acid or at least one pH adjuster selected from amino acids having an isoelectric point of 5.5 to 6.5 is prescribed. Characterized in that it is contained at a ratio of

(A) Chloroprene homopolymer latex A chloroprene homopolymer latex is blended in order to improve the contact property, heat resistance, and initial adhesion of a one-part aqueous adhesive using a latex composition. The chloroprene homopolymer latex is obtained by dispersing a chloroprene homopolymer in water in an emulsified state, and is obtained by emulsion polymerization of chloroprene using an emulsifier.
The chloroprene homopolymer contained in the chloroprene homopolymer latex has a gel content (toluene-insoluble content) of 30% by mass or less, a toluene-soluble number average molecular weight of 200,000 to 500,000, and a molecular weight distribution (Mw / Mn). Is preferably in the range of 2.0 to 4.0.

As the emulsifier used for the emulsion polymerization, rosin acid or an alkali metal salt thereof is used. When rosin acid or an alkali metal salt thereof is used as an emulsifier, the emulsion stability of the latex composition is easily reduced when a mechanical stimulus is applied to the latex composition. Therefore, when the latex composition is used as an adhesive, excellent initial adhesive strength can be exhibited.

The most preferred emulsifier used in the emulsion polymerization is rosin acid, and any of wood rosin acid, gum rosin acid, tall oil rosin acid, and disproportionated rosin acid obtained by disproportionating these can be used. The addition amount of rosin acid is preferably from 0.5 to 10 parts by mass, more preferably from 2 to 6 parts by mass, based on 100 parts by mass of the whole simple substance used. When the amount is less than 0.5 part by mass, emulsification failure is apt to occur, so that problems such as deterioration of polymerization heat control, generation of agglomerates, and poor product appearance tend to occur. If the amount is more than 10 parts by mass, water resistance of the polymer is deteriorated due to the remaining emulsifier, and problems such as a decrease in adhesive strength, foaming during drying, and deterioration of the color tone of the product are likely to occur.

When rosin acid is used, it is preferable to use a sulfate-based or sulfonate-based anionic emulsifier or dispersant in combination to stabilize the chloroprene homopolymer latex after adding the pH adjuster. In this case, the addition amount of the anionic emulsifier or dispersant other than rosin acid is preferably from 0.05 to 5 parts by mass, more preferably from 0.1 to 2 parts by mass, based on 100 parts by mass of all the monomers used. is there.

Examples of anionic emulsifiers and dispersants other than rosin acid include alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonate.

As the emulsifier, a nonionic emulsifier or dispersant may be used in combination. By using a nonionic emulsifier in combination, it is possible to improve the low-temperature stability of the latex composition and the adhesive properties when used as an adhesive. When a nonionic or cationic emulsifier or dispersant is used alone as an emulsifier or dispersant during emulsion polymerization, sufficient instability does not occur when a pH adjuster is added to form an aqueous adhesive. However, the expression of the initial adhesive strength may be insufficient.

At the time of emulsion polymerization of chloroprene, a chain transfer agent is used to adjust the molecular weight and molecular weight distribution of the chloroprene polymer. Examples of the chain transfer agent include long-chain alkyl mercaptans such as n-dodecyl mercaptan and t-dodecyl mercaptan, and dialkyl xanthogen disulfides such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide. From the viewpoint that the molecular weight and the gel content are easily controlled, it is preferable to use long-chain alkyl mercaptans. Two or more of these chain transfer agents may be used in combination.

The polymerization conversion of the raw material monomer in the chloroprene homopolymer latex is preferably 65% by mass or more and less than 90% by mass. When the polymerization conversion is less than 65%, the solid content of the polymer latex is reduced, and not only does the drying step after application of the adhesive impose a load or it is difficult to make the adhesive layer uniform, Problems such as deterioration of odor, adhesive strength, and adhesive strength due to residual monomers may occur. When the polymerization conversion is 90% by mass or more, the number of branches increases in the polymer or the molecular weight increases, so that the molecular weight distribution is widened, and the problems of deteriorating the contact performance and water resistance, which are important performances in the present invention. May cause. When a polymer having a conversion of 90% by mass or more is used, it is preferably used as an auxiliary component of a polymer having a conversion of less than 90% by mass. The polymerization conversion rate (% by mass) is determined by [(sum of polymer mass / monomer mass) × 100].

The chloroprene homopolymer can be polymerized in the range of 5 to 45 ° C, but is preferably polymerized at a low temperature of 5 to 20 ° C. It is known that trans-1,4-linkage accounts for 85% or more of chloroprene homopolymer, and its molecular structure is relatively rich in regularity. Chloroprene homopolymer has properties as a typical crystalline polymer due to the high regularity of the molecular structure. By setting the polymerization temperature to a low temperature of 5 to 20 ° C., the ratio of trans-1,4-bond in the polychloroprene molecule is further increased, so that a chloroprene homopolymer having a higher crystallization rate can be obtained. When this is used as a one-component water-based adhesive, a sufficient adhesive strength is achieved.

As the initiator for the emulsion polymerization, a usual radical polymerization initiator can be used, and specifically, an organic or inorganic peroxide such as benzoyl peroxide, potassium persulfate, ammonium persulfate, or azobisisobutyrate. An azo compound such as lonitrile is used. A co-catalyst such as anthraquinone sulfonate, potassium sulfite and sodium sulfite may be appropriately used in combination.

In the production of a chloroprene homopolymer, in order to obtain a polymer having a desired molecular weight and distribution, when a predetermined polymerization rate is reached, a polymerization terminator is added to stop the reaction. Examples of the polymerization terminator include phenothiazine, pt-butylcatechol, hydroquinone, hydroquinone monomethyl ether, and diethylhydroxylamine.

The solid content concentration of the chloroprene homopolymer latex is not particularly limited, but is usually 40 to 65% by mass. The proportion of the chloroprene homopolymer latex in the latex mixture is 50 to 90% by mass in terms of solid content. If the amount is less than 50% by mass, the feeling of the obtained adhesive layer is not flexible, and the synergistic effect of containing the chloroprene copolymer latex described below is not exhibited. If the amount is more than 90% by mass, the storage stability may be deteriorated or the initial adhesive strength may be reduced unless a pH adjuster described below is added.

Chloroprene homopolymer latex is generally susceptible to degradation by oxygen. In the present invention, it is desirable to appropriately use a stabilizer such as an antioxidant as long as the effects of the present invention are not impaired.

The amount of the antioxidant added to the chloroprene homopolymer latex is preferably 0.1 to 3 parts by mass based on 100 parts by mass of the solid content of the chloroprene homopolymer latex. By setting it in this range, the stability over time of the flexibility of the obtained adhesive layer can be improved. When the antioxidant is insoluble in water or destabilizes the emulsified state of the chloroprene homopolymer latex, it may be added to an aqueous dispersion before preparing it.

(B) Chloroprene copolymer latex A chloroprene copolymer latex is used to adjust the storage stability and the feel (hardness) of the adhesive layer while maintaining the initial adhesive force of the adhesive using the latex composition. It is to be blended.

The chloroprene copolymer latex is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, and the content of the binding unit derived from 2,3-dichloro-1,3-butadiene is 5 to 5. It is preferably 50% by mass. The chloroprene copolymer contained in the chloroprene copolymer latex preferably has a monomer polymerization conversion of 65% by mass or more and less than 95% by mass.

The chloroprene copolymer contained in the chloroprene copolymer latex is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene. The chloroprene copolymer may be further copolymerized with another copolymerizable monomer. Other copolymerizable monomers include 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, and methacrylic acid and its esters. Can be copolymerized within a range that does not impair the performance. The copolymerization amounts of 2,3-dichloro-1,3-butadiene and these other copolymerizable monomers are 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, Preferably, butadiene, isoprene, styrene, acrylonitrile, acrylates and methacrylates are in the range of 0.01 to 20% by mass, and acrylic acid and methacrylic acid are in the range of 0.01 to 7% by mass. Two or more monomers constituting the copolymer may be used as necessary. Further, two or more kinds of polymers may be used as a mixture. Among them, the chloroprene copolymer constituting the chloroprene copolymer latex is a chloroprene homopolymer, a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, or a chloroprene homopolymer and chloroprene and 2,3. It is preferable to use a mixture of a copolymer with -dichloro-1,3-butadiene, because the adhesive strength of the obtained one-component aqueous adhesive is increased. When another copolymerizable monomer is used in combination with chloroprene, if the content of the binding unit derived from the other copolymerizable monomer in the copolymer exceeds 20% by mass, the initial adhesive strength and contact It is not preferable because the property is lowered.

In order to obtain a chloroprene copolymer latex, these monomers may be emulsion-polymerized. Stabilizers such as an emulsifier, a chain transfer agent, a polymerization initiator, a polymerization terminator, and an antioxidant used for emulsion polymerization may be those used in emulsion polymerization of chloroprene homopolymer latex.

The polymerization conversion of the raw material monomer in the chloroprene copolymer latex is preferably 65% by mass or more and less than 90% by mass. When the polymerization conversion is less than 65%, the solid content of the polymer latex is reduced, and not only does the drying step after application of the adhesive impose a load or it is difficult to make the adhesive layer uniform, Problems such as deterioration of odor, adhesive strength, and adhesive strength due to residual monomers may occur. When the polymerization conversion is 90% by mass or more, the number of branches increases in the polymer or the molecular weight increases, so that the molecular weight distribution is widened, and the problems of deteriorating the contact performance and water resistance, which are important performances in the present invention. May cause. When a polymer having a conversion of 90% by mass or more is used, it is preferably used as an auxiliary component of a polymer having a conversion of less than 90% by mass. The polymerization conversion rate (% by mass) is determined by [(sum of polymer mass / monomer mass) × 100].

The chloroprene copolymer can be polymerized in the range of 5 to 50 ° C, but is preferably polymerized at a high temperature of 30 to 50 ° C. By performing emulsion polymerization in this range, the ratio of trans-1,4-bonds in the chloroprene copolymer can be intentionally reduced to further reduce the crystallization rate. For this reason, the adhesive layer of the obtained one-component water-based adhesive has a soft texture. From the viewpoint of slowing down the crystallization rate, it is preferable to use a monomer other than chloroprene in combination to reduce the regularity of the molecular structure.

The solid content concentration of the chloroprene copolymer latex in the chloroprene copolymer latex is not particularly limited, but is usually 40 to 65% by mass. The proportion of the chloroprene copolymer latex in the latex mixture is 50 to 85% by mass in terms of solid content. If it is less than 50% by mass, the effect of softening the feel of the adhesive layer cannot be obtained. If the amount is more than 85% by mass, the storage stability may deteriorate or the initial adhesive strength may decrease unless a pH adjuster described below is contained.

(C) pH adjuster The pH adjuster is compounded to improve the initial adhesive strength and storage stability of the latex composition. As the pH adjuster, a weak acid or a buffer solution can be used, and boric acid or at least one compound selected from amino acids having an isoelectric point of 5.5 to 6.5 is used.
Specific examples of the amino acid having an isoelectric point of 5.5 to 6.5 include glycine (5.97), alanine (6.00), threonine (6.16), and proline (6.30). . It is preferable to use glycine, which is a kind of amino acid, from the viewpoint of cost, adhesion performance, ease of handling, and the like.

The amount of the pH adjuster is not particularly limited, but an amount that can adjust the pH of the adhesive composition to a range of 7 to 10 should be used. More preferably, it is desirable to adjust the pH range to 8 to 10.

When boric acid is used as the pH adjuster, it is preferable to use it as a 5% concentration aqueous solution because handling becomes easy. When glycine is used as the pH adjuster, it is preferably 1 to 20 parts by mass, more preferably 2 to 16 parts by mass, and still more preferably 100 parts by mass (solid content) of chloroprene homopolymer latex. 3 to 13 parts by weight are used. If the added amount of glycine is too small, sufficient adhesive strength will not be exhibited, and storage stability will decrease. If the addition amount is too large, it is disadvantageous in terms of cost, aggregates are generated at the time of addition, and storage stability decreases.

In the latex composition of the present invention, in addition to the components (A), (B), and (C), if necessary, (D) a plasticizer represented by the following general formula (1) in an amount of 1 to 20 mass%. Parts can be added.

（式中、Ｒ_１及びＲ_３は炭素原子数１〜３の脂肪族アルキル基もしくは水素原子を表し、Ｒ_１およびＲ_３は同じ構造でも異なる構造でもよい。Ｒ_２は炭素原子数５〜２０の脂肪族アルキル基を表す。）
上記記載の可塑剤を添加することで、得られる接着剤層の風合いを柔軟にしたり、乾燥時間（Ｏｐｅｎ ｔｉｍｅ、Ｏ．Ｔ．）が長くなっても接着力を維持することができる。

(Wherein, R ₁ and R ₃ represent an aliphatic alkyl group having 1 to ₃ carbon atoms or a hydrogen atom, and R ₁ and R ₃ may have the same structure or different structures. R ₂ has 5 to 20 carbon atoms. Represents an aliphatic alkyl group.)
By adding the above-described plasticizer, the texture of the obtained adhesive layer can be softened, and the adhesive strength can be maintained even when the drying time (Open time, OT) becomes long.

The amount of the plasticizer represented by the general formula (1) is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and still more preferably 5 parts by mass with respect to 100 parts by mass (solid content) of the latex composition. The range is from 10 to 10 parts by mass. If the added amount of the plasticizer is small, the adhesive strength when the drying time is extended may be reduced. When the amount of the plasticizer is large, the initial adhesive strength may be reduced, and the cost may be disadvantageous.

The latex composition of the present invention preferably contains (E) a hindered phenolic antioxidant. The hindered phenolic antioxidant has an effect of improving discoloration and hygiene of a protruding part (greenine) of the adhesive when the latex composition is used as an adhesive. Hindered phenolic antioxidants include 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'- Examples include butylidenebis (3-methyl-6-tert-butylphenol) and the butylated reaction product of p-cresol and dicyclopentadiene. The amount of the hindered phenolic antioxidant to be added is preferably 0.1 to 3% by mass, more preferably 0.5 to 2% by mass, based on 100 parts by mass of the solid content of the latex composition. If the amount of the antioxidant is less than 0.1% by mass, the antioxidant effect is not sufficient, and if it exceeds 3% by mass, the adhesive strength and the adhesive strength may be deteriorated.

In the latex composition of the present invention, as long as the effects of the present invention are not impaired, fillers, tackifiers, pigments, coloring agents, wetting agents, defoamers, thickeners, etc. It can be used as appropriate. Other resin emulsions (latex) may be supplementarily compounded up to 10% by mass (in terms of solid content) of the total composition. Specific examples include (modified) vinyl acetate, vinyl acetate / acrylic mixture, acrylic / styrene mixture, and resin emulsions such as urethane.

The method for preparing the latex composition is not particularly limited, but if the pH is less than 9, the colloid of the latex mixture becomes unstable, so that (A) chloroprene homopolymer latex and (B) chloroprene copolymer A method is preferred in which latex is blended, and then (C) a pH adjuster is added. It is preferable that each auxiliary component is also added as an aqueous dispersion. The latex composition thus obtained can be used as it is as a one-part aqueous adhesive.

A preferable adherend of the one-component aqueous adhesive is a foam made of a material such as polyurethane, ethylene-vinyl acetate copolymer, or polyethylene, or a water-absorbent adherend such as wood, cloth, or fabric. There is.

The polymer latex composition manufactured under the above conditions has a flexible adhesive layer, and has excellent initial adhesive strength and contact properties, water resistance, spray coating properties, and storage stability. It can be suitably used as a water-based adhesive.

Hereinafter, the present invention will be specifically described with reference to examples. These examples do not limit the invention. In the following examples, parts and% are based on mass unless otherwise specified.

[Experimental example 1]
Production of Chloroprene Homopolymer Latex A-1 Using a 3 liter reactor, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.06 part of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. under a nitrogen atmosphere. When the final polymerization rate reached 65%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-1. The gel content of the chloroprene homopolymer latex A-1 was 0%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 2]
Production of Chloroprene Homopolymer Latex A-2 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate in a 3 liter reactor under a nitrogen stream. After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.06 part of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. under a nitrogen atmosphere. When the final polymerization rate reached 70%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-2. The gel content of the chloroprene homopolymer latex A-2 was 5%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 3]
Production of Chloroprene Homopolymer Latex A-3 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.06 part of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere. When the final polymerization rate reached 85%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-3. The gel content of the chloroprene homopolymer latex A-3 was 30%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 4]
Production of Chloroprene Homopolymer Latex A-4 Using a reactor having an inner volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.06 part of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure and concentration was performed, and the solid content concentration was adjusted to 55% by mass to obtain chloroprene homopolymer latex A-4. The gel content of the chloroprene homopolymer latex A-4 was 40%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 5]
Production of Chloroprene Homopolymer Latex A-5 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.14 part of n-dodecylmercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, the water was evaporated under reduced pressure to concentrate, and the concentration of the solid content was adjusted to 55% by mass to obtain chloroprene homopolymer latex A-5. The gel content of the chloroprene homopolymer latex A-5 was 15%, the Mn of the toluene-soluble component was 100,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 6]
Production of Chloroprene Homopolymer Latex A-6 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.10 part of n-dodecylmercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, the water was evaporated under reduced pressure to concentrate the solution, and the solid content concentration was adjusted to 55% by mass to obtain chloroprene homopolymer latex A-6. The gel content of the chloroprene homopolymer latex A-6 was 15%, the Mn of the toluene-soluble component was 250,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 7]
Production of Chloroprene Homopolymer Latex A-7 In a 3 liter reactor, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.10 part of n-dodecylmercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 5 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure and concentration was performed, and the solid content concentration was adjusted to be 55% by mass to obtain chloroprene homopolymer latex A-7. The gel content of the chloroprene homopolymer latex A-7 was 15%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 2.0.

[Experimental example 8]
Production of Chloroprene Homopolymer Latex A-8 In a 3 liter reactor, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium rosinate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate After 0.3 part of sodium salt and 0.3 part of sodium bisulfite were charged and dissolved, 100 parts of chloroprene monomer and 0.08 part of n-dodecylmercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, the water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-8. The gel content of the chloroprene homopolymer latex A-8 was 15%, the Mn of the toluene-soluble component was 300,000, and the molecular weight distribution (Mw / Mn) was 4.0.

[Experimental example 9]
Production of Chloroprene Homopolymer Latex A-9 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium alkyldiphenyletherdisulfonate, 0.5 part of potassium hydroxide, formaldehyde naphthalenesulfonic acid 0.3 parts of a sodium salt of a condensate and 0.3 parts of sodium bisulfite were charged, and after dissolution, 100 parts of a chloroprene monomer and 0.10 parts of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-9. The gel content of the chloroprene homopolymer latex A-9 was 15%, the Mn of the toluene-soluble component was 250,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 10]
Production of Chloroprene Homopolymer Latex A-10 Using a reactor having an inner volume of 3 L, under a nitrogen stream, 100 parts of pure water, 5 parts of sodium alkylbenzenesulfonate, 0.5 parts of potassium hydroxide, formaldehyde naphthalenesulfonic acid condensation After charging and dissolving 0.3 part of sodium salt and 0.3 part of sodium bisulfite, 100 parts of chloroprene monomer and 0.10 part of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure and concentration was performed, and the solid content concentration was adjusted to 55% by mass to obtain chloroprene homopolymer latex A-10. The gel content of the chloroprene homopolymer latex A-10 was 15%, the Mn of the toluene-soluble component was 250,000, and the molecular weight distribution (Mw / Mn) was 2.5.

[Experimental example 11]
Production of Chloroprene Homopolymer Latex A-11 Using a 3 liter internal volume reactor under a nitrogen stream, 100 parts of pure water, 5 parts of sodium polyoxyethylene sulfate, 0.5 part of potassium hydroxide, formaldehyde naphthalene sulfonic acid 0.3 parts of a sodium salt of a condensate and 0.3 parts of sodium bisulfite were charged, and after dissolution, 100 parts of a chloroprene monomer and 0.10 parts of n-dodecyl mercaptan were added with stirring. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 10 ° C. in a nitrogen atmosphere, and when the final polymerization rate reached 80%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 55% by mass to obtain a chloroprene homopolymer latex A-11. The gel content of the chloroprene homopolymer latex A-11 was 15%, the Mn of the toluene-soluble component was 250,000, and the molecular weight distribution (Mw / Mn) was 2.5.

The gel content, Mn (number average molecular weight) and molecular weight distribution (Mw / Mn) of these chloroprene homopolymer latexes A-1 to A-11 are values measured by the following methods.
[Gel content]
After freeze-drying each sample, the sample was precisely weighed and designated as X. This was dissolved in toluene (adjusted to 0.6%), and after using a centrifugal separator, a gel component was separated using a 200-mesh wire net. After the separated gel component was air-dried, it was dried in an atmosphere of 110 ° C. for 1 hour, and its mass was precisely weighed to be Y.

The gel content was calculated by the following equation (1).

[Mn and molecular weight distribution of soluble matter in toluene (Mw / Mn)]
GPC measurement was performed under the following conditions to measure the molecular weight in terms of polystyrene, and the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were evaluated. The measurement was performed by preparing a toluene-soluble component (sol) separated by the gel component content measurement in a 0.1% tetrahydrofuran (THF) solution.

Measurement device: Tosoh HLC-8120GPC
Analytical column: TSK-GEL GMH _HR- H (5 μm) × 3, manufactured by Tosoh Corporation, size 7.8 mmφ × 300 mm
Guard Column: Guard column TSK- Guard Column TSK- guard column _H HR -H _(5μm), size diameter: 6 mm × 40 mm, column temperature: 40 ° C.
Solvent: THF special grade, flow rate: 1 ml / min

[Experimental example 12]
Production of Chloroprene Copolymer Latex B-1 Using a 3 liter reactor, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium rosinate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate 0.5 part of sodium salt and 0.5 part of sodium bisulfite were charged, and after dissolution, 99 parts of chloroprene, 1 part of 2,3-dichloro-1,3-butadiene and 0.04 part of n-dodecylmercaptan were stirred. Was added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-1.

[Experimental example 13]
Production of Chloroprene Copolymer Latex B-2 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium rosinate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate 0.5 part of sodium salt and 0.5 part of sodium bisulfite were charged and dissolved, and after stirring, 95 parts of chloroprene, 5 parts by mass of 2,3-dichloro-1,3-butadiene and 0.04 part of n-dodecyl mercaptan were added. Parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-2.

[Experimental example 14]
Production of Chloroprene Copolymer Latex B-3 Using a reactor having an inner volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium rosinate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate 0.5 part of sodium salt and 0.5 part of sodium bisulfite were charged, and after dissolution, 90 parts of chloroprene, 10 parts by mass of 2,3-dichloro-1,3-butadiene, and 0.04 part of n-dodecyl mercaptan were stirred. Parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-3.

[Experimental example 15]
Production of Chloroprene Copolymer Latex B-4 Using a reactor having an inner volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium rosinate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate 0.5 part of a sodium salt and 0.5 part of sodium bisulfite were charged, and after dissolving, 50 parts by mass of chloroprene, 50 parts by mass of 2,3-dichloro-1,3-butadiene and 0.04 part of n-dodecyl mercaptan were stirred. Parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-4.

[Experimental example 16]
Production of Chloroprene Copolymer Latex B-5 Using a reactor having an inner volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium rosinate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid condensate 0.5 part of sodium salt and 0.5 part of sodium bisulfite were charged, and after dissolving, 40 parts of chloroprene, 60 parts by mass of 2,3-dichloro-1,3-butadiene and 0.04 part of n-dodecyl mercaptan were stirred. Parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-5.

[Experimental example 17]
Production of Chloroprene Copolymer Latex B-6 Using a reactor having an inner volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium alkyldiphenyletherdisulfonate, 1.5 parts of potassium hydroxide, formaldehyde naphthalenesulfonic acid 0.5 part of a sodium salt of a condensate and 0.5 part of sodium bisulfite were charged and dissolved. After stirring, 90 parts of chloroprene, 10 parts by mass of 2,3-dichloro-1,3-butadiene, and 0 part of n-dodecylmercaptan were added. .04 parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-6.

[Experimental example 18]
Production of Chloroprene Copolymer Latex B-7 100 parts of pure water, 4 parts of sodium alkylbenzenesulfonate, 1.5 parts of potassium hydroxide, 1.5 parts of formaldehyde naphthalene sulfonic acid condensation in a nitrogen gas stream using a reactor having a volume of 3 liters Of sodium chloride and 0.5 part of sodium bisulfite, and after dissolution, 90 parts of chloroprene, 10 parts by weight of 2,3-dichloro-1,3-butadiene and 0.1 part of n-dodecylmercaptan were stirred. 04 parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, the water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-7.

[Experimental example 19]
Production of Chloroprene Copolymer Latex B-8 Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of pure water, 4 parts of sodium polyoxyethylene sulfate, 1.5 parts of potassium hydroxide, formaldehyde naphthalene sulfonic acid 0.5 part of a sodium salt of a condensate and 0.5 part of sodium bisulfite were charged and dissolved. After stirring, 90 parts of chloroprene, 10 parts by mass of 2,3-dichloro-1,3-butadiene, and 0 part of n-dodecylmercaptan were added. .04 parts were added. Using 0.1 part by weight of potassium persulfate as an initiator, polymerization was carried out at 40 ° C. under a nitrogen atmosphere, and when the final polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing unreacted monomers under reduced pressure, 0.3 parts of a polyoxyalkylene alkyl ether as a low-temperature stabilizer was added to 100 parts of solids with stirring. Further, water was evaporated under reduced pressure to concentrate the solution, and the solid content was adjusted to 60% by mass to obtain a chloroprene copolymer latex B-8.

The following emulsifiers or dispersants were used in the production of the chloroprene homopolymer latex and the chloroprene copolymer latex in Examples and Comparative Examples.
Sodium rosinate: 3R-70N manufactured by Arakawa Chemical Industries, Ltd.
Alkyl diphenyl ether disulfonic acid sodium: Perex SSH manufactured by Kao Corporation
Sodium alkylbenzene sulfonate: NEOPEREX G-15 manufactured by Kao Corporation
Sodium polyoxyethylene sulfate: Latemul E-118B manufactured by Kao Corporation
Naphthalenesulfonic acid formaldehyde condensate sodium salt: Demol N manufactured by Kao Corporation

[PH regulator]
The following pH adjusters C-1 to C-7 were used in the aqueous adhesive compositions of Examples and Comparative Examples.
C-1. Glycine (isoelectric point: 5.97)
C-2. Alanine (isoelectric point: 6.00)
C-3. Threonine (isoelectric point: 6.16)
C-4.5% boric acid aqueous solution (prepared by dissolving 5 g of boric acid (powder) in 95 g of pure water)
C-5. Proline (isoelectric point: 6.30)
C-6. Phenylalanine (isoelectric point: 5.48)
C-7. Histidine (isoelectric point: 7.59)

[Other reagents]
The following reagents were used in the aqueous adhesive compositions of Examples and Comparative Examples.
Dibutyl sebacate: Plasticizer Nipol LX820A, manufactured by Taoka Chemical Industry Co., Ltd. Acrylic latex, manufactured by Zeon Corporation

[Preparation of one-component aqueous adhesive]
The pH regulators C-1 to C-7 were added to 100 parts by mass (in terms of solid content) of the chloroprene homopolymer latex A-1 to A-11 and the chloroprene copolymer latex B-1 to B-8 in total. In addition, the one-component aqueous adhesives of Examples 1 to 21 and Comparative Examples 1 to 34 were prepared in addition to the amounts shown in Tables 1 to 5.
The initial adhesive strength, the texture of the adhesive layer, the durometer hardness of the dried sheet, and the storage stability of the obtained one-component aqueous adhesive were measured by the following methods. The measurement results are shown in Tables 1 to 5.

[Initial adhesive strength]
Using a polyurethane foam having a density of 30 kg / m ³ (thickness 20 mm × length 50 mm × width 50 mm) as an adherend, a one-component aqueous adhesive was spray-coated so as to be 70 g / m ^{2 in} a 23 ° C. atmosphere. . After the application, the adhesive is left for 10 seconds or 1 minute in an atmosphere of 23 ° C., and the adhesive surfaces of the two polyurethane foams are overlapped with each other while the one-component aqueous adhesive is not dried, and the thickness is reduced from 40 mm to 10 mm. Hold for 5 seconds. Immediately thereafter, a tensile test was performed in a direction perpendicular to the adhesive surface with a tensile tester (Autograph manufactured by Shimadzu Corporation: tensile speed: 200 mm / min), and the initial adhesive force (N / cm ² ) was measured.
The case where the initial adhesive strength was 3.0 N / cm ² or more was regarded as acceptable.

[Handle of adhesive layer]
Using a polyurethane foam having a density of 30 kg / m ³ (thickness: 20 mm × length: 50 mm × width: 50 mm) as an adherend in the same manner as in the method of evaluating the initial adhesive force, 70 g of a one-component aqueous adhesive was used at 23 ° C. in an atmosphere. / M ² . After the application, the mixture was allowed to stand in an atmosphere at 23 ° C. for 1 minute. Then, the adhesive surfaces of the two polyurethane foams were overlapped with each other while the one-component aqueous adhesive was not dried, and the thickness was reduced from 40 mm to 10 mm and held for 5 seconds. . Then, after leaving at 23 ° C. for 24 hours, the feel of the adhesive layer was evaluated by touch of a finger. A sample in which the texture of the polyurethane foam and the adhesive layer were equal was evaluated as ○, a sample in which the texture of the adhesive was slightly harder than the polyurethane foam was evaluated as △, and a sample in which the adhesive layer was harder than the polyurethane foam was evaluated as ×.

[Durometer hardness of dried sheet (Type A)]
An adhesive compounded so as to have a thickness of about 3.5 mm is poured into a Teflon (registered trademark) petri dish, dried at 23 ° C. for 5 days, and volatile components are evaporated to obtain a dry sheet. Further, the dried sheet was dried using a vacuum dryer (DP-41, manufactured by Yamato Scientific Co., Ltd.) at 23 ° C. for 2 days, and then the durometer hardness (type A) specified in JIS K 6253-3 was measured.
A case where the durometer hardness (type A) was in the range of 30 to 70 was regarded as acceptable.

[Storage stability]
After heat-treating 250 g of the one-component aqueous adhesive at 40 ° C. for 7 days, the presence or absence and the state of the increase in viscosity were observed. A sample in which the viscosity of the one-component aqueous adhesive did not change was evaluated as ○, and a sample in which coagulation or coagulation occurred was evaluated as ×.

As shown in the evaluation results of Tables 1 to 5, the one-part aqueous adhesives of Examples 1 to 21 having the composition within the specified range according to the present invention have an initial adhesive strength, a feeling of an adhesive layer, and a durometer hardness of a dry sheet. (Type A) and storage stability were all good.

In contrast, Comparative Examples 2 to 4 and 13 to 24, which did not use a rosinate or its alkali metal salt during emulsion polymerization and used an emulsifier other than the above, had an initial adhesive strength of 3.0 N / cm. It was not good at ² or less.

In Comparative Examples 1 to 5, 9, 13, 17 and 21 containing the regulation according to the present invention, but the blending ratio was out of the prescribed range, the feeling of the adhesive layer was not good.

Furthermore, Comparative Examples 25 and 27 in which the amount of the pH adjuster according to the present invention was out of the specified range had an initial adhesive strength, and Comparative Examples 26 and 28 did not have good storage stability of the adhesive. In addition, when a pH adjusting agent other than the specified type was used as in Comparative Examples 29 and 30, agglomeration and coagulation occurred when the adhesive was compounded, and the physical properties of adhesion could not be evaluated. Was.

As in Comparative Examples 5 to 12, when the content of the monomer unit of 2,3-dichloro-1,3-butadiene in the chloroprene copolymer latex is out of the specified range, the texture of the adhesive layer, Durometer hardness was not good.

When dibutyl sebacate (plasticizer) was added to the chloroprene homopolymer latex as in Comparative Example 31, good initial adhesive strength was obtained, but the feel of the adhesive layer was not good.

As in Comparative Examples 32 to 34, when an adhesive was prepared by mixing the chloroprene homopolymer latex with the acrylic latex in the composition shown in Table 5, the texture of the adhesive layer was good, but the initial adhesive strength was not good. The storage stability of the adhesive was not good.

Claims (5)

(A) A chloroprene homopolymer latex containing a chloroprene homopolymer obtained by emulsion polymerization of chloroprene using rosin acid or an alkali metal salt thereof is 50 to 90% by mass in terms of solid content; A chloroprene copolymer latex containing a chloroprene copolymer obtained by emulsion polymerization of 2,3-dichloro-1,3-butadiene using rosin acid or an alkali metal salt thereof is 10 to 50 mass in terms of solid content. % Of a latex mixture having 100% by weight (in terms of solid content);
(C) 3 to 7 parts by mass (in terms of solid content) of boric acid or at least one pH adjuster selected from amino acids having an isoelectric point of 5.5 to 6.5;
Contain,
A latex composition wherein the (B) chloroprene copolymer has a content of a binding unit derived from 2,3-dichloro-1,3-butadiene of 5 to 50% by mass .   The chloroprene homopolymer has a gel content (toluene-insoluble content) of 30% by mass or less, a toluene-soluble component having a number average molecular weight of 200,000 to 500,000, and a molecular weight distribution (Mw / Mn) of 2.0 to 4 2. The latex composition according to claim 1, wherein the latex composition is 1.0. The latex composition according to claim 1 or 2 , wherein a durometer hardness (type A) defined by JIS K 6253-3 of the dried sheet obtained by drying the latex composition is 30 to 70. The latex composition according to any one of claims 1 to 3, wherein the chloroprene homopolymer and the chloroprene copolymer have a monomer polymerization conversion of 65% by mass or more and less than 95% by mass. One-aqueous adhesive comprising a latex composition according to any one of claims 1-4.