JP2013173938A - Chloroprene latex and adhesive composition containing chloroprene latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chloroprene latex which has a controlled pH and is usable over a long period of time while maintaining latex stability in storage, and provide use of an adhesive composition containing the same.SOLUTION: A chloroprene latex is characterized by containing an acid of which a minus common logarithmic value (pKa) of acid dissociation constant (Ka) of its water solution at 25°C is 7 or lower, an emulsifier which is formed of a carboxylic alkali metal salt, and 1.0-2.0 pts.wt. of a stabilizer which is formed of a sulfonate alkali metal salt with respect to 100 pts.wt. of chloroprene, and having a pH 9.0-12.0 at 25°C. An adhesive composition is characterized by containing the chloroprene latex.

Description

  The present invention relates to a chloroprene latex having good latex stability even when stored for a long period of time.

  Solvent-based adhesives based on chloroprene rubber and the like have been used for various applications because of their good workability and adhesive properties. However, since the organic solvent used has an adverse effect on the global environment and the health of workers, and sometimes has a risk of causing a fire in the workplace, etc., solvent removal has been studied.

  As one of the methods of solvent removal, substitution with latex adhesive is considered.In particular, chloroprene latex is expected to show high strength immediately after bonding, but it takes time to dry water. It was a problem.

  As one method for solving this problem, a pH adjuster is added to a chloroprene latex containing sodium hydroxide and potassium hydroxide polymerized using an emulsifier composed of rosin acid and / or a metal salt of rosin acid, and pH = There is a method of using 7-10 chloroprene latex adhesive (for example, Patent Document 1). As this pH adjuster, acidic substances such as general inorganic acids and organic acids and salts thereof, and amino acids are used. In terms of adhesion performance and latex stability, amino acids such as glycine, alanine, phenylalanine, glutamic acid and the like It is stated that malonic acid is preferred.

  An emulsifier made of an alkali metal salt of a carboxylic acid such as rosin acid loses its effectiveness as an emulsifier when neutralized with an acid, thereby reducing the stability of the latex. However, it is possible to adjust the pH without precipitating rubber by using the above-mentioned amino acids, etc., and as a result, the adhesive is easy to precipitate when adhered in a wet state, and exhibits an excellent adhesive property. Can be stably produced.

  In this way, the one-pack type chloroprene latex adhesive adjusted in pH by adding a pH adjusting agent in advance is mixed with a curing agent immediately before use, or a latex adhesive (main agent) and a pH adjusting agent (flocculating agent). Unlike the two-pack type chloroprene latex adhesive, which is separately adjusted and sprayed at the time of use, it is one of the advantages that there is no complicated operation and no time restriction from adjustment to use. For this reason, storage stability by long-term storage is also considered an important performance. Since chloroprene latex generally dehydrochlorinates during storage, this one-pack type chloroprene latex adhesive has problems such as precipitation of rubber during storage due to a decrease in latex stability due to a further decrease in pH. there is a possibility. Nevertheless, at present, no investigation has been made on the storage stability of chloroprene latex to which a pH adjusting agent has been added.

JP 2001-19922 A

  The present invention has been made in view of this problem, and an object of the present invention is to maintain the stability of latex during storage in a chloroprene latex adjusted in pH and to be used for a long period of time. A composition is provided.

  Under these circumstances, the present inventors have intensively studied to solve the above-mentioned problems. As a result, the chloroprene latex composed of a specific acid, a specific emulsifier and a specific stabilizer suppresses aggregation of rubber during storage. As a result, the present invention has been completed. That is, the present invention relates to an acid having a negative common logarithm (pKa) of an acid dissociation constant (Ka) of an aqueous solution at 25 ° C. of 7 or less, an emulsifier comprising an alkali metal salt of a carboxylic acid, and 100 parts by weight of chloroprene. A chloroprene latex characterized by containing 1.0 to 2.0 parts by weight of a stabilizer comprising an alkali metal salt of sulfonic acid and having a pH of 9.0 to 12.0 at 25 ° C. It is an adhesive composition characterized by containing.

  Hereinafter, the present invention will be described in detail.

  The chloroprene latex of the present invention is a latex obtained by polymerizing a monomer of chloroprene, which is 2-chloro-1,3-butadiene, and, if necessary, other monomer that can be copolymerized with chloroprene. Two or more types of bodies may be used. Examples of other monomers copolymerizable with chloroprene include 2,3-dichloro-1,3 butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monoacrylate. , Polyethylene glycol monomethacrylate, glycerin monomethacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, 2-methacryloyloxyethyl succinic acid, etc., but these are based on 100 parts by weight of chloroprene, Used at 20 parts by weight or less.

  The chloroprene latex of the present invention contains an acid whose negative common logarithm (pKa) of acid dissociation constant (Ka) at 25 ° C. of the aqueous solution is 7 or less. When pKa exceeds 7, problems such as lowering of pH and precipitation of rubber occur in the latex during storage. The acid dissociation constant Ka is the equilibrium constant of the ionization equilibrium of the acid in the ionized aqueous solution of the acid. The stronger the acid, the larger the value and the smaller the pKa. Examples of the acid having a pKa of 7 or less include hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, malonic acid, malic acid, citric acid and the like. Of these, acids having a carboxyl group such as formic acid, acetic acid, oxalic acid, malic acid, malonic acid and citric acid are preferred for the stability of pH and safety during handling in a concentrated state. Or the use of citric acid is preferred. These may be one type or may include two or more types. Moreover, content of the acid whose pKa is 7 or less is not specifically limited.

  The chloroprene latex of the present invention contains an emulsifier composed of an alkali metal salt of a carboxylic acid. By including an emulsifier composed of an alkali metal salt of carboxylic acid, it is possible to improve the adhesive properties by adjusting the pH. The content of the emulsifier is not particularly limited, but is preferably 3 to 6 parts by weight with respect to 100 parts by weight of the chloroprene monomer for polymerization control. Examples of emulsifiers composed of alkali metal salts of carboxylic acids include, for example, alkali metal salts of rosin acids, alkali metal salts of fatty acids, alkali metal salts of alkenyl succinic acids, and polymer compounds of alkali metal salts of polycarboxylic acids. Can be given. Examples of the alkali metal salt include lithium, sodium, potassium, cesium and the like. These may be one type or may include two or more types. From the viewpoint of adhesive performance, it is preferable to use an alkali metal salt of rosin acid.

  The chloroprene latex of the present invention contains 0.5 to 5 parts by weight of a stabilizer composed of an alkali metal salt of sulfonic acid with respect to 100 parts by weight of chloroprene. If the stabilizer comprising an alkali metal salt of sulfonic acid is less than 0.5 parts by weight, the neutralization stability is poor and rubber is precipitated by addition of acid, whereas if it exceeds 5 parts by weight, the adhesive properties may be adversely affected. There is sex. In order to maintain neutralization stability and good adhesive properties, the content is preferably 0.7 to 3.0 parts by weight, and more preferably 1.0 to 2.0 parts by weight. Examples of the stabilizer made of an alkali metal salt of sulfonic acid include an alkali metal salt of pentane sulfonic acid, an alkali metal salt of octane sulfonic acid, an alkali metal salt of lauryl sulfonic acid, an alkali metal salt of stearyl sulfonic acid, etc. Alkali metal salt of aliphatic sulfonic acid, alkali metal salt of toluene sulfonic acid, alkali metal salt of styrene sulfonic acid, alkali metal salt of dodecylbenzene sulfonic acid, alkali metal salt of alkyldiphenyl ether sulfonic acid, alkali metal of naphthalene sulfonic acid Polyoxyethylene salt such as alkali metal salt of aromatic sulfonic acid such as alkali metal salt of butylnaphthalene sulfonic acid salt, alkyl sulfate salt such as alkali metal salt of lauryl sulfate, alkali metal salt of polyoxyethylene lauryl ether sulfate Ethylene alkyl ether sulfates alkali metal salts, condensates of alkali metal salts of naphthalene sulfonic acid and formalin, and various copolymers of monomers copolymerizable with alkali metal salts of sulfonic acid compounds having an unsaturated bond And various compounds having an alkali metal salt of a sulfonic acid compound (specifically, a copolymer of an alkali metal salt of styrene sulfonic acid and an alkali metal salt of methacrylic acid). Examples of the sulfonic acid compound having an unsaturated bond include an alkali metal salt of vinyl sulfonic acid, an alkali metal salt of allyl sulfonic acid, an alkali metal salt of methallyl sulfonic acid, an alkali metal salt of isoprene sulfonic acid, and styrene sulfonic acid. Examples of the monomers copolymerizable therewith include acrylic acid, methacrylic acid, fumaric acid, maleic acid, methyl methacrylate, and alkali metal salts thereof. Examples of the alkali metal salt include lithium, sodium, potassium, cesium and the like. These may be one type or two or more types. Among these, in terms of polymerization stability and adhesive physical properties in a wet state, the number of carbon atoms such as an alkali metal salt of pentanesulfonic acid, an alkali metal salt of styrenesulfonic acid, an alkali metal salt of butylnaphthalenesulfonic acid, etc. is 6 or less. Preferred is an alkali metal salt of a sulfonic acid having an alkyl chain, an alkali metal salt of an aromatic sulfonic acid having no alkyl chain, and various compounds having these. It is preferable to use one or more of a copolymer of an alkali metal salt of an acid and an alkali metal salt of methacrylic acid.

  The chloroprene latex of the present invention has a pH of 9.0 to 12.0 at 25 ° C. If the pH is less than 9.0, rubber precipitates during compounding due to the precipitation of rubber, while if it exceeds 12.0, problems such as insufficient rubber precipitation during bonding and insufficient strength occur. In order to achieve both blending stability and adhesive properties, the pH is preferably 9.0 to 11.5, and more preferably pH 9.5 to 10.5.

  In the chloroprene latex of the present invention, the gel content of the chloroprene polymer contained in the latex is preferably 1% by weight or less for good contact expression.

  In the method for producing a chloroprene latex of the present invention, an acid having a negative common logarithm (pKa) of an acid dissociation constant (Ka) of an aqueous solution at 25 ° C. of 7 or less, an emulsifier comprising an alkali metal salt of a carboxylic acid, and chloroprene It is necessary to add 0.5 to 5 parts by weight of a stabilizer made of an alkali metal salt of sulfonic acid with respect to 100 parts by weight.

  The addition amount of the acid having a pKa of 7 or less is not particularly limited, and the acid is added by adjusting the amount so that the latex has an arbitrary pH. Moreover, although the addition time is not particularly limited, it is preferably carried out in a state in which the chloroprene latex is stirred in order to prevent rubber precipitation. The state of the acid at the time of addition is not particularly limited and can be added as a powder or an aqueous solution, but it is uniformly mixed in the latex and maintains the solid content of the adhesive to maintain the drying property. Addition in the form of a powder or a concentrated aqueous solution is preferred.

  The addition amount of the emulsifier composed of an alkali metal salt of carboxylic acid is not particularly limited, but is preferably 3 to 6 parts by weight with respect to 100 parts by weight of the chloroprene monomer for polymerization control. Further, not only before the polymerization but also during the polymerization, additional addition at any timing after the completion of the polymerization is possible. Moreover, in order to maintain alkalinity at the time of superposition | polymerization, it is preferable to add 0.2-0.5 weight part of water-soluble substances which show alkalinity, such as sodium hydroxide, potassium hydroxide, diethanolamine, and triethanolamine.

  The stabilizer composed of an alkali metal salt of sulfonic acid needs to be added in an amount of 0.5 to 5 parts by weight with respect to 100 parts by weight of chloroprene. If the amount is less than 0.5 parts by weight, the neutralization stability is poor and rubber is precipitated by the addition of an acid. On the other hand, if it exceeds 5 parts by weight, the adhesive properties may be adversely affected. In order to maintain neutralization stability and good adhesive properties, the content is preferably 0.7 to 3.0 parts by weight, and more preferably 1.0 to 2.0 parts by weight. Further, the addition timing is not particularly limited, and the addition can be performed at any timing before, during, or after the polymerization.

  The method for polymerizing chloroprene in the method for producing chloroprene latex is not particularly limited, and chloroprene monomer or other monomer copolymerizable with chloroprene monomer and chloroprene may be subjected to radical emulsion polymerization. . Examples of other monomers copolymerizable with chloroprene include 2,3-dichloro-1,3 butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monoacrylate. , Polyethylene glycol monomethacrylate, glycerin monomethacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, 2-methacryloyloxyethyl succinic acid, etc., for example, 100 parts by weight of chloroprene On the other hand, it is used at 20 parts by weight or less. Emulsion polymerization is not particularly limited, and the above-mentioned monomer and emulsifier are emulsified together with a polymerization initiator, a chain transfer agent, etc., performed at a predetermined temperature, and a polymerization terminator is added at a predetermined conversion rate. That's fine.

  As the polymerization initiator, a known free radical substance such as a peroxide such as potassium persulfate or ammonium persulfate, or an inorganic or organic peroxide such as hydrogen peroxide or tertiary butyl hydroperoxide may be used. it can. These may be used alone or in combination with a reducing substance, for example, a combined redox system with thiosulfate, thiosulfite, hydrosulfite, organic amine and the like.

  Examples of the chain transfer agent include molecular weight regulators such as alkyl mercaptans, halogen hydrocarbons, alkyl xanthogen disulfides, and sulfur. Among these, n-dodecyl mercaptan is preferable from the viewpoint of odor and workability.

  The polymerization temperature is not particularly limited and can be carried out in the range of 0 to 80 ° C, preferably in the range of 10 to 50 ° C.

  Although the completion | finish time of superposition | polymerization is not specifically limited, In order to obtain productivity and favorable adhesive property, it is preferable to superpose | polymerize until the conversion rate of a monomer is 60-100%.

  The polymerization terminator is not particularly limited as long as it is a commonly used terminator, and for example, phenothiazine, 2,6-tert-butyl-4-methylphenol, hydroxylamine and the like can be used.

  Further, in order to further improve the stability of the latex, one or more of the above emulsifiers may be added during and after the polymerization.

  The adhesive containing the chloroprene latex of the present invention can be used alone as an adhesive by adjusting the pH, but a tackifying resin, a crosslinking agent, etc. can be added depending on the required physical properties.

  The tackifying resin is not particularly limited, and examples thereof include phenol resins, terpene resins, rosin derivative resins, petroleum hydrocarbons, and the like, such as polymerized rosin, rosin modified resin, rosin modified phenol resin, rosin. Esters, alkylphenol resins, terpene resins, terpene phenols, hydrogenated rosins, hydrogenated rosin pentaerythritol esters, petroleum resins, coumarone resins, and the like are used.

  As the cross-linking agent, for example, a metal oxide such as magnesium oxide, calcium oxide, zinc oxide, an epoxy resin, a polyaziridine compound, a polyoxazoline compound, a polyisocyanate compound, or the like can be used as long as it is a compound that can be uniformly mixed with chloroprene latex. it can.

  The viscosity of the adhesive mainly composed of chloroprene latex is composed of various thickeners, for example, water-soluble polymers such as polyalkylene oxide, polyvinyl alcohol, hydrophobic cellulose, associative nonionic surfactants, and carboxyl group-containing polymers. It can be adjusted to a desired value by blending an alkali-soluble thickener and a silicate compound such as hectorite. Moreover, you may mix | blend various fillers, such as anti-aging agent, antiseptic | preservative, antifreezing agent, film-forming aid, a plasticizer, clay, as needed.

  The chloroprene latex of the present invention does not aggregate rubber during long-term storage, and as a result, the adhesive composition containing it exhibits stable physical properties.

  The chloroprene latex of the present invention has an effect that the pH is stable during long-term storage and there is no precipitation of rubber, and the adhesive composition containing the same exhibits stable physical properties.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to only these examples. The storage period in Examples and Comparative Examples was one month at 25 ° C., or 7 days or more at 50 ° C. as the corresponding acceleration condition. Each physical property was measured by the following method.

<Polymer gel content>
The latex was cast to produce a rubber film, which was weighed after 24 hours or more in a vacuum dryer, and thereafter weighed repeatedly every 8 hours until the weight change was 1% or less. Thereafter, the rubber is dissolved in toluene so as to have a concentration of 0.6% in terms of weight, mixed and dissolved in a ball mill for 16 hours, and the resulting solution is filtered through a 200 mesh wire net and washed with toluene. Thereafter, the residue was dried at 170 ° C. for 10 minutes, and the ratio of the weight to the weight of the dissolved rubber was taken as the gel content.

<PH>
It was measured with a pH meter (manufactured by Horiba, Ltd.).

<Neutralization stability>
The presence or absence of rubber precipitation during acid addition was observed.

<Compounding stability>
The presence or absence of rubber precipitation during the blending of the adhesive was observed.

<Blending viscosity>
After immersing the adhesive container in a thermostatic bath at 25 ° C. for 1 hour, No. Measurement was performed at 6 rpm using 3 rotors, and the value after 60 seconds was used.

<Adhesive strength>
About 690 g / m ² of adhesive was applied to one side of each of No. 9 canvas (150 mm × 25 mm), dried at 23 ° C. for 5 minutes, and then pressure-bonded using a hand roller to obtain a test specimen for measurement. The room temperature peel strength was measured by using a Tensilon-type tensile tester and pulling in a 180 ° direction at a peeling rate of 100 mm / min in an atmosphere at 23 ° C. The measurement was performed 2 minutes after the pressure bonding.

Example 1
For 100 parts by weight of chloroprene monomer, 0.15 part of n-dodecyl mercaptan, 5 parts by weight of potassium rosinate (trade name: Longis K-25, Arakawa Chemical Co., Ltd.), 0.4 part by weight of sodium hydroxide, A chloroprene latex was prepared by polymerizing 0.01 parts by weight of hydrosulfite sodium and 80 parts by weight of pure water at 20 ° C. in a 10 L autoclave equipped with a stirrer. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached 90% or more, a polymerization terminator was added to stop the reaction. Unreacted monomer was removed under reduced pressure to obtain chloroprene latex. The solid content of the chloroprene latex was 50%, and the gel content of the chloroprene polymer in the latex was 0% by weight.

  To the obtained chloroprene latex, 0.7 parts by weight of sodium naphthalene sulfonate and formalin condensate (trade name: Demol N, Kao Co., Ltd.) in terms of solid content of chloroprene latex was added as a stabilizer, and then latex. 150 g is weighed and 2.1 g of 30% aqueous citric acid solution (pKa1 = 3.2, pKa2 = 4.7, pKa3 = 6.4 at 25 ° C. of citric acid) is used to form a latex having a pH of 9.7. Obtained. The pH change of this latex during storage at 50 ° C. was measured. Also, 40 parts by weight of resin emulsion and 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industry Co., Ltd.) An adhesive composition was prepared by blending 2 parts by weight of a thickener (trade name: Adecanol UH-420, ADEKA Corporation), and blending stability and adhesive strength were confirmed. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

実施例２
安定剤としてナフタレンスルホン酸ナトリウムとホルマリンの縮合物（商品名：デモールＮ、花王（株））の添加量をクロロプレンラテックスの固形分換算で１．５重量部に変更した以外は実施例１に従ってラテックスを得て、評価を実施した。結果を表１に示す。表１の結果より、酸によるｐＨ調節時にゴムの析出は無く中和安定性は良好で、５０℃保管によるｐＨも安定でありゴムの析出も無かった。また、配合安定性および接着物性も良好であった。

Example 2
Latex according to Example 1 except that the amount of sodium naphthalene sulfonate and formalin condensate (trade name: Demol N, Kao Co., Ltd.) added as a stabilizer was changed to 1.5 parts by weight in terms of solid content of chloroprene latex. And evaluated. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

Example 3
A latex was obtained and evaluated in accordance with Example 1 except that sodium pentanesulfonate was added as a stabilizer in place of the condensate of sodium naphthalenesulfonate and formalin in an amount of 1.5 parts by weight in terms of solid content of chloroprene latex. did. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

Example 4
A latex was obtained and evaluated in accordance with Example 1 except that sodium styrenesulfonate was added as a stabilizer in place of the condensate of sodium naphthalenesulfonate and formalin in an amount of 1.5 parts by weight in terms of the solid content of the chloroprene latex. did. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

Example 5
According to Example 1, except that 0.7 parts by weight of a copolymer of sodium styrenesulfonate and sodium methacrylate was added as a stabilizer in place of the condensate of sodium naphthalenesulfonate and formalin in terms of solid content of chloroprene latex. Latex was obtained and evaluated. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

Example 6
According to Example 1 except that a copolymer of sodium styrene sulfonate and sodium methacrylate was added as a stabilizer in place of the condensate of sodium naphthalene sulfonate and formalin in an amount of 1.7 parts by weight in terms of solid content of chloroprene latex. Latex was obtained and evaluated. The results are shown in Table 1. From the results shown in Table 1, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, the pH was stable after storage at 50 ° C., and there was no rubber precipitation. In addition, blending stability and adhesive properties were good.

Comparative Example 1
A latex was obtained and evaluated according to Example 1 except that the amount of sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) added as a stabilizer was changed to 0.3 parts by weight. did. The results are shown in Table 1. From the results in Table 1, rubber was precipitated during pH adjustment with acid.

Comparative Example 2
A latex was obtained according to Example 1 and evaluated, except that the amount of the copolymer of sodium styrenesulfonate and sodium methacrylate added was changed to 0.3 parts by weight as a stabilizer. The results are shown in Table 1. From the results in Table 1, rubber was precipitated during pH adjustment with acid.

Example 7
100 parts by weight of chloroprene monomer, 0.15 parts by weight of n-dodecyl mercaptan, 5 parts by weight of potassium rosinate (trade name: Longis K-25, Arakawa Chemical Co., Ltd.), condensation of sodium naphthalenesulfonate and formalin (Product name: Demol N, Kao Co., Ltd.) 0.3 parts by weight, sodium hydroxide 0.4 parts by weight, hydrosulfite sodium 0.01 parts by weight, and pure water 80 parts by weight in a 10 L autoclave with a stirrer Polymerization was carried out at 20 ° C. to prepare a chloroprene latex. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached 90% or more, a polymerization terminator was added to stop the reaction. Unreacted monomers were removed under reduced pressure and water was concentrated to obtain a chloroprene latex having a solid content of 55%. The gel content of the chloroprene polymer in the latex was 0% by weight.

  To the obtained chloroprene latex, a condensate of sodium naphthalene sulfonate and formalin (trade name: Demol N, Kao Co., Ltd.) as a stabilizer was added in an amount of 1.1 parts by weight in terms of solid content of the chloroprene latex to give a total of 1.4. After setting to parts by weight, 150 g of latex was weighed and 2.9 g of 20% aqueous acetic acid solution (pKa of acetic acid at 25 ° C .: 4.8) was used to obtain a latex having a latex pH of 9.7. The latex was stored at 50 ° C. and the change in pH was measured. Also, 40 parts by weight of resin emulsion and 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industry Co., Ltd.) An adhesive composition was prepared by blending 2 parts by weight of a thickener (trade name: Adecanol UH-420, ADEKA Co., Ltd.), and blending stability, blending viscosity change at 50 ° C. storage and adhesive properties were confirmed. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good.

実施例８
実施例７に従って重合を行い、安定剤としてナフタレンスルホン酸ナトリウムとホルマリンの縮合物（商品名：デモールＮ、花王（株））をクロロプレンラテックスの固形分換算で１．１重量部を加え合計１．４重量部とした後、ラテックス１５０ｇを秤量し、２０％酢酸水溶液の代わりに１０％のマロン酸水溶液４．８ｇ（マロン酸の２５℃におけるｐＫａ１＝２．８，ｐＫａ２＝５．７）を用いてラテックスのｐＨを９．７とした以外は実施例５に従ってラテックスｐＨおよび接着剤組成物の粘度変化を測定した。結果を表２に示す。表２の結果より、酸によるｐＨ調節時にゴムの析出は無く中和安定性は良好で、５０℃保管によるゴムの析出も無かった。また、配合安定性も良好で、配合粘度も比較的安定な値であり、接着物性も良好であった。配合粘度も比較的安定な値であった。

Example 8
Polymerization was carried out in accordance with Example 7, and a sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer was added in an amount of 1.1 parts by weight in terms of the solid content of chloroprene latex. After 4 parts by weight, 150 g of latex was weighed and 4.8 g of 10% malonic acid aqueous solution (pKa1 = 2.8, pKa2 = 5.7 at 25 ° C. of malonic acid) was used instead of 20% acetic acid aqueous solution. Then, the latex pH and the viscosity change of the adhesive composition were measured according to Example 5 except that the pH of the latex was 9.7. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good. The compounding viscosity was also a relatively stable value.

Example 9
Polymerization was carried out in accordance with Example 7, and a sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer was added in an amount of 1.1 parts by weight in terms of the solid content of chloroprene latex. After 4 parts by weight, 150 g of latex was weighed, and 2.1 g of 30% aqueous citric acid solution instead of 20% aqueous acetic acid (pKa1 = 3.2, pKa2 = 4.7 at 25 ° C. of citric acid = pKa3 = The latex pH and the viscosity change of the adhesive composition were measured according to Example 5 except that the pH of the latex was changed to 9.7 using 6.4). The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good. The compounding viscosity was also a relatively stable value.

Example 10
Polymerization was carried out according to Example 7, and 1.1 parts by weight of a sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer in terms of solid content of chloroprene latex was added to give a total of 1.4. After the weight was adjusted, 150 g of latex was weighed, and 9.7 g of 3.5% hydrochloric acid (pKa of 25 ° C. or less of hydrochloric acid at 1 ° C .: 1 or less) was used in place of the 20% acetic acid aqueous solution. Except that, the latex pH and the viscosity change of the adhesive composition were measured according to Example 5. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good.

Example 11
100 parts by weight of chloroprene monomer, 0.15 parts by weight of n-dodecyl mercaptan, 5 parts by weight of potassium rosinate (trade name: Longis K-25, Arakawa Chemical Co., Ltd.), sodium styrenesulfonate and sodium methacrylate A chloroprene latex was prepared by polymerizing 0.3 parts by weight of a copolymer, 0.4 parts by weight of sodium hydroxide, 0.01 parts by weight of hydrosulfite sodium, and 80 parts by weight of pure water in a 10 L autoclave with a stirrer at 20 ° C. Produced. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached 90% or more, a polymerization terminator was added to stop the reaction. Unreacted monomers were removed under reduced pressure and water was concentrated to obtain a chloroprene latex having a solid content of 55%. The gel content of the chloroprene polymer in the latex was 0% by weight.

  To the obtained chloroprene latex, 1.1 parts by weight of a sodium phthalene sulfonate and formalin condensate as a stabilizer in terms of solid content of the chloroprene latex was added to a total of 1.4 parts by weight, and then 150 g of latex was weighed. A latex having a latex pH of 9.7 was obtained using 2.8 g of a 20% acetic acid aqueous solution (pKa of acetic acid at 25 ° C .: 4.8). The latex was stored at 50 ° C. and the change in pH was measured. Also, 40 parts by weight of resin emulsion and 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industry Co., Ltd.) An adhesive composition was prepared by blending 2 parts by weight of a thickener (trade name: Adecanol UH-420, ADEKA Co., Ltd.), and blending stability, blending viscosity change at 50 ° C. storage and adhesive properties were confirmed. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good.

Example 12
For 100 parts by weight of chloroprene monomer, 0.15 parts by weight of n-dodecyl mercaptan, 5 parts by weight of potassium rosinate (trade name: Longis K-25, Arakawa Chemical Co., Ltd.), styrene sulfonic acid and sodium methacrylate Polymerize 1.4 parts by weight of copolymer, 0.4 parts by weight of sodium hydroxide, 0.01 parts by weight of hydrosulfite sodium, and 80 parts by weight of pure water in a 10 L autoclave with a stirrer at 20 ° C. to prepare chloroprene latex. did. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached 90% or more, a polymerization terminator was added to stop the reaction. Unreacted monomers were removed under reduced pressure and water was concentrated to obtain a chloroprene latex having a solid content of 55%. The gel content of the chloroprene polymer in the latex was 0.1% by weight.

  150 g of the obtained chloroprene latex was weighed, and a latex having a latex pH of 9.7 was obtained using 2.9 g of a 20% aqueous acetic acid solution (pKa of acetic acid at 25 ° C .: 4.8). The latex was stored at 50 ° C. and the change in pH was measured. Also, 40 parts by weight of resin emulsion and 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industry Co., Ltd.) An adhesive composition was prepared by blending 2 parts by weight of a thickener (trade name: Adecanol UH-420, ADEKA Co., Ltd.), and blending stability, blending viscosity change at 50 ° C. storage and adhesive properties were confirmed. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and there was no rubber precipitation when stored at 50 ° C. Also, the blending stability was good, the blending viscosity was a relatively stable value, and the adhesive properties were also good.

Comparative Example 3
After performing the polymerization according to Example 7, without adding a stabilizer, 4.8 g of 10% malonic acid aqueous solution instead of 20% acetic acid aqueous solution (pKa1 = 2.8, pKa2 = 25 ° C. of malonic acid at 25 ° C.) The latex pH and the viscosity change of the adhesive composition were measured according to Example 5 except that the pH of the latex was changed to 9.7 using 5.7). The results are shown in Table 2. From the results in Table 2, rubber was precipitated during pH adjustment with acid.

Comparative Example 4
After performing the polymerization according to Example 7, 150 g of latex was weighed without adding a stabilizer, and 0.7 g of glycine powder (pKa of glycine at 25 ° C .: 9.8) was used instead of a 20% aqueous acetic acid solution. The latex pH and the viscosity change of the adhesive composition were measured according to Example 5, except that the latex pH was 9.7. The results are shown in Table 2. From the results shown in Table 2, rubber was not precipitated when pH was adjusted with acid and the neutralization stability was good, but rubber was precipitated when stored at 50 ° C.

Comparative Example 5
Polymerization was carried out in accordance with Example 7, and a sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer was added in an amount of 1.1 parts by weight in terms of the solid content of chloroprene latex. After 4 parts by weight, 150 g of latex was weighed, and the pH of the latex was adjusted to 9.7 using 0.7 g of glycine powder (pKa at 25 ° C .: 9.8) instead of 20% acetic acid aqueous solution. The latex pH and the viscosity change of the adhesive composition were measured according to Example 5 except for the above. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, and the neutralization stability was good. However, there was a tendency for the rubber to precipitate and the compounding viscosity to increase when stored at 50 ° C.

Comparative Example 6
Polymerization was carried out in accordance with Example 7, and a sodium naphthalene sulfonate-formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer was added in an amount of 1.1 parts by weight in terms of the solid content of chloroprene latex. After 4 parts by weight, 150 g of latex was weighed, and 0.8 g of β-alanine powder (pKa at 25 ° C. at 10.degree. C. at 10.2) was used instead of 20% acetic acid aqueous solution to adjust the pH of the latex to 9.7. Except that, the pH of the latex was adjusted according to Example 5, and the latex pH and the viscosity change of the adhesive composition were measured. The results are shown in Table 2. From the results shown in Table 2, there was no rubber precipitation when the pH was adjusted with acid, and the neutralization stability was good, but the pH dropped to less than 9 after storage at 50 ° C.

Example 13
For 100 parts by weight of chloroprene monomer, 0.15 parts by weight of n-dodecyl mercaptan, 5 parts by weight of potassium rosinate (trade name: Longes K-25, Arakawa Chemical Co., Ltd.), condensation of sodium naphthalenesulfonate and formalin (Product name: Demol N, Kao Co., Ltd.) 0.3 parts by weight, sodium hydroxide 0.4 parts by weight, hydrosulfite sodium 0.01 parts by weight, and pure water 80 parts by weight in a 10 L autoclave with a stirrer Polymerization was carried out at 20 ° C. to prepare a chloroprene latex. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached 90% or more, a polymerization terminator was added to stop the reaction. Unreacted monomer was removed under reduced pressure to obtain chloroprene latex. The solid content of the chloroprene latex was 50%, and the gel content of the chloroprene polymer in the latex was 0%.

  To the obtained chloroprene latex, 1.1 parts by weight of sodium naphthalene sulfonate and formalin condensate (trade name: Demol N, Kao Co., Ltd.) as a stabilizer in terms of solid content of chloroprene latex was added. % Acetic acid aqueous solution 2.3 g, 2.6 g, and 3.3 g (pKa of acetic acid at 25 ° C .: 4.8) were added to obtain latexes having pHs of 11.5, 10.5, and 9.3, respectively.

  40 parts by weight of resin emulsion and 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industries, Ltd.) An adhesive composition was prepared by blending 2 parts by weight of a sticking agent (trade name: Adecanol UH-420, ADEKA Co., Ltd.), stored at 50 ° C. for 10 days, and change in viscosity of the adhesive composition during storage. Was measured. The results are shown in Table 3. From the results shown in Table 3, there was no rubber precipitation when the pH was adjusted with acid, the neutralization stability was good, and the adhesive properties were also good. Moreover, the compounding viscosity by storage at 25 ° C. for 30 days was a relatively stable value.

比較例７
２０％酢酸水溶液を加えなかった以外は実施例１３に従ってラテックスを製造し、評価を実施した。結果を表３に示す。表３の結果より、圧着２分後の強度が低く、また、配合粘度も増加する傾向がみられた。

Comparative Example 7
A latex was produced according to Example 13 and evaluated, except that no 20% aqueous acetic acid solution was added. The results are shown in Table 3. From the results shown in Table 3, the strength after 2 minutes of pressure bonding was low and the blending viscosity tended to increase.

Comparative Example 8
A latex was produced and evaluated according to Example 13 except that 3.8 g of a 20% aqueous acetic acid solution was added to adjust the pH at 25 ° C. to 8.7. The results are shown in Table 3. From the results shown in Table 3, there was no problem in the neutralization stability and the adhesive strength, but rubber was precipitated when the adhesive was blended, and the blending stability was poor. Further, rubber was precipitated and solidified during storage.

Claims (4)

An acid having a negative common logarithm (pKa) of an acid dissociation constant (Ka) of an aqueous solution at 25 ° C. of 7 or less, an emulsifier comprising an alkali metal salt of a carboxylic acid, and an alkali metal of sulfonic acid with respect to 100 parts by weight of chloroprene A chloroprene latex comprising 1.0 to 2.0 parts by weight of a stabilizer comprising a salt and having a pH of 9.0 to 12.0 at 25 ° C. The chloroprene latex according to claim 1, wherein the emulsifier comprising an alkali metal salt of a carboxylic acid is potassium rosinate or sodium rosinate. The stabilizer comprising an alkali metal salt of sulfonic acid is a condensate of an alkali metal salt of naphthalene sulfonic acid and formalin and / or a copolymer of an alkali metal salt of styrene sulfonic acid and an alkali metal salt of methacrylic acid. The chloroprene latex according to claim 1 or 2. An adhesive composition comprising the chloroprene latex according to any one of claims 1 to 3.