JP2012092196A - Chloroprene latex, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chloroprene latex that exhibits good adhesion retention at a high temperature and good adhesive strength.SOLUTION: The chloroprene latex includes a copolymer of chloroprene and 2,3-dichlorobutadiene, and the copolymer is characterized in that the amount of 2,3-dichlorobutadiene is 6-135 pts.wt. based on 100 pts.wt. chloroprene; the gel content is 1-80 wt.%; and one or more endothermic peaks are present between 30°C and 45°C and between 50°C and 100°C in a DSC measurement curve of the copolymer. The method for producing the chloroprene latex is provided.

Description

  The present invention relates to a chloroprene latex having good adhesive properties and, in particular, good adhesion retention in a high temperature atmosphere, and a method for producing the same. In addition, the high temperature atmosphere in this invention points out 80 degreeC.

  The adhesive is required to have initial adhesive strength, heat resistant adhesive strength, water resistant adhesive strength, and the like. In particular, in a line of a factory or the like, bonding is performed in a state of being heated and dried at high temperature, and therefore, adhesive holding power in a high temperature atmosphere is required so that it is not peeled off immediately after bonding.

  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, 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. Therefore, the demand for solvent removal is increasing.

  As one of the methods for removing the solvent, substitution with a latex adhesive is considered.

  Various types of chloroprene latex are known (for example, Patent Documents 1 to 4).

  However, as shown in Patent Documents 1 and 2, when a water-soluble polymer such as polyvinyl alcohol is used, the latex exhibits excellent latex stability due to its protective colloid properties, while the expected adhesive properties are obtained. In particular, the water-resistant adhesive strength is lowered. On the other hand, as shown in Patent Documents 3 and 4, there is no problem of water resistance when an emulsifier made of a metal salt of rosin acid is used, and techniques for improving heat-resistant adhesive strength have been studied (for example, Patent Documents). 5) It cannot be said that it is sufficient as compared with solvent-based adhesives, and it is extremely important to improve the adhesive retention at high temperatures.

JP-A-6-287360 JP 11-335491 A Japanese Patent Publication No.51-39262 Japanese Patent Laid-Open No. 51-136733 JP 2010-6902 A

  This invention is made | formed in view of this problem, and provides the chloroprene latex which improves the adhesive retention power of the conventional chloroprene latex at high temperature, and its manufacturing method.

  Under these circumstances, the present inventors have intensively studied to solve the above-mentioned problems. As a result, the latex contains a copolymer of chloroprene and 2,3-dichlorobutadiene, and the gel content of the copolymer is reduced. By using a chloroprene latex that is 1 to 80% by weight and has one or more endothermic peaks between 30 to 45 ° C and 50 to 100 ° C in the DSC measurement curve of the crystallized copolymer, The present inventors have found that the adhesive strength is good and that the adhesive holding strength and adhesive strength (ordinary temperature adhesive strength, heat resistant adhesive strength) particularly at high temperatures are exhibited, thereby completing the present invention. That is, the present invention includes a copolymer of chloroprene and 2,3-dichlorobutadiene, and the copolymer is 6 to 135 parts by weight of 2,3-dichlorobutadiene with respect to 100 parts by weight of chloroprene and has a gel content. A chloroprene latex characterized in that one or more endothermic peaks exist between 30 to 45 ° C. and 50 to 100 ° C. in the DSC measurement curve of the copolymer, It is a manufacturing method.

  Hereinafter, the present invention will be described in detail.

  The chloroprene latex of the present invention contains a copolymer of chloroprene and 2,3-dichlorobutadiene. By including a copolymer of chloroprene and 2,3-dichlorobutadiene, the adhesion retention at high temperatures can be improved.

  The content of chloroprene and 2,3-dichlorobutadiene in the copolymer of chloroprene and 2,3-dichlorobutadiene is 6 to 135 parts by weight, preferably 10 to 135 parts by weight, per 100 parts by weight of chloroprene. ~ 60 parts by weight. When 2,3-dichlorobutadiene is less than 6 parts by weight or more than 135 parts by weight, one or more endothermic peaks do not exist between 30 to 45 ° C. and 50 to 100 ° C., and adhesion strength and high temperature Adhesive retention strength at the time is reduced.

  The gel content in the copolymer of chloroprene and 2,3-dichlorobutadiene is 1 to 80% by weight, preferably 10 to 60% by weight. When the gel content is less than 1% by weight, the heat-resistant adhesive strength and the adhesive retention at high temperatures are poor, and when the gel content exceeds 80% by weight, the adhesive strength may be inferior due to poor adhesion. Here, the gel content refers to a high molecular weight material in which CR such as toluene is insoluble in a soluble organic solvent.

  The chloroprene latex of the present invention has one or more endothermic peaks between 30 to 45 ° C. and 50 to 100 ° C. in the DSC measurement curve of the copolymer of chloroprene and 2,3-dichlorobutadiene. . The presence of one or more endothermic peaks between 30 to 45 ° C. and 50 to 100 ° C. improves adhesion retention at high temperatures. Here, the endothermic peak in DSC is measured by extracting rubber from the latex.

  The chloroprene latex of the present invention preferably contains an emulsifier in order to obtain good stability and adhesive properties. Examples of the emulsifier include an anionic emulsifier and a nonionic emulsifier. Examples of the anionic emulsifier include an alkali metal salt of rosin acid, an alkali metal salt of fatty acid, an alkali metal salt of alkenyl succinic acid, and an alkali metal of polycarboxylic acid. Emulsifiers composed of carboxylates such as polymer compounds of metal salts, alkali metal salts of alkane sulfonic acids, emulsifiers composed of sulfonic acids such as alkylbenzene sulfonates, sulfuric acids such as alkyl sulfate esters, polyoxyethylene alkyl ether sulfates Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, glycerin fatty acid ester, and polyvinyl alcohol. Among these, an anionic emulsifier is preferable in order to obtain better stability and adhesive properties, and among them, an alkali metal salt of rosin acid is preferable.

  The chloroprene latex of the present invention may be chloroprene latex alone or a mixture of a plurality of chloroprene latexes. When mixing, it is preferable to mix so that the ratio of 2, 3- dichlorobutadiene with respect to the whole may be 10 to 60 weight%. Further, a latex containing 10% by weight or more of 2,3-dichlorobutadiene or a latex containing no 2,3-dichlorobutadiene with respect to a latex having a proportion of 2,3-dichlorobutadiene of 10% by weight or less or 60% by weight or more. It is also possible to prepare the above amount by mixing.

  In addition, the solid content of the chloroprene latex of the present invention is not particularly limited, but in order to obtain good adhesive properties by securing the thickening at the time of thickener blending and the amount of adhesive after coating and drying. It is preferable that it is 50% or more.

  The chloroprene latex of the present invention can be produced by emulsion polymerization of a chloroprene monomer and a 2,3-dichlorobutadiene monomer.

  Emulsion polymerization is carried out at a predetermined temperature by emulsifying a predetermined amount of the above monomer and emulsifier together with a predetermined amount of n-dodecyl mercaptan as a polymerization initiator and a chain transfer agent, and a predetermined conversion rate. And a polymerization terminator may be added. If necessary, it may further contain one or more other monomers copolymerizable with chloroprene. The polymerization method is not particularly limited. For example, chloroprene monomer and 2,3-dichlorobutadiene monomer, or chloroprene monomer, 2,3-dichlorobutadiene monomer and chloroprene can be copolymerized. Any other monomer may be radically copolymerized. Moreover, you may add each monomer during superposition | polymerization.

  As the chain transfer agent, n-dodecyl mercaptan is used in terms of odor and workability.

  The amount of n-dodecyl mercaptan used from the beginning of the polymerization is 0.005 to 0.1 parts by weight with respect to 100 parts by weight of the chloroprene monomer, and is preferable in order to obtain a balanced initial adhesive strength and heat resistant adhesive strength. Is 0.005 to 0.01 parts by weight. When it is less than 0.005 parts by weight or more than 0.1 parts by weight, the gel content does not become a predetermined numerical value.

  When the polymerization conversion is 60 to 90%, n-dodecyl mercaptan is added in the range of 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the chloroprene monomer. When n-dodecyl mercaptan is not added or when it is added outside the range of 0.01 to 0.3 parts by weight, the adhesive properties may be deteriorated. Preferably, it is 0.01-0.1 weight part.

  When the polymerization conversion is 60 to 90%, 6 to 54 parts by weight of 2,3-dichlorobutadiene monomer is added so as to satisfy the following formula with respect to 100 parts by weight of chloroprene monomer, preferably 10 Add ~ 40 parts by weight to satisfy the following formula.

(100-C) × 0.6 <X ≦ (100-C) × 1.35
(In the formula, X represents a part by weight of 2,3-dichlorobutadiene monomer to be added, and C represents a polymerization conversion rate.)
If these conditions are not met, there is no endothermic peak between 30-45 ° C and 50-100 ° C.

  Other monomers copolymerizable with chloroprene include, for example, monomers containing a carboxyl group such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, and 2-methacryloyloxyethyl succinic acid. Examples include a monomer, 2,3-dichloro-1,3 butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, and glycerin monomethacrylate. .

  The emulsifier is not particularly limited as long as it is generally used for emulsion polymerization, and examples thereof include an anionic emulsifier and a nonionic emulsifier. Examples of the anionic emulsifier include alkali metal salts of rosin acid, fatty acid It consists of emulsifiers consisting of carboxylates such as alkali metal salts, alkali metal salts of alkenyl succinic acid, alkali metal salts of polycarboxylic acids, alkali metal salts of alkane sulfonic acids, sulfonic acids such as alkylbenzene sulfonates, etc. Examples include emulsifiers, sulfates such as alkyl sulfates and polyoxyethylene alkyl ether sulfates, and examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, glycerin fatty acid esters, and polyvinyl alcohol. Examples of the alkali metal salt include lithium, sodium, potassium, cesium and the like. Among these, anionic emulsifiers are preferable from the viewpoint of polymerization stability and adhesive properties, and among these, alkali metal salts of rosin acid are preferable. The amount used is not particularly limited, but usually 3 to 7 parts by weight of these are used with respect to 100 parts by weight of the monomer.

  From the viewpoint of latex stability, it is common to use a stabilizer such as a condensate of naphthalene sulfonate and formaldehyde in combination. The amount of the stabilizer is not particularly limited.

  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.

  The polymerization temperature is not particularly limited, but is 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 80-95%.

  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.

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

  The chloroprene latex of the present invention can be used alone as an adhesive, but the adhesive properties are improved by using a chloroprene latex composition to which a tackifier resin or a crosslinking agent is added.

  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 crosslinking agent, for example, any polyfunctional compound that can be uniformly mixed with chloroprene latex, such as a polyisocyanate compound, an epoxy resin, a polyaziridine compound, and a polyoxazoline compound, can be used without any limitation.

  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. The viscosity can be adjusted to a desired level by blending an alkali-soluble thickener and a silicate compound such as hectorite.

  The chloroprene latex composition contained other additives such as a thickener, an anti-aging agent, an antiseptic, an antifreezing agent, a film-forming aid, a plasticizer, clay, and a pH adjuster as necessary. Things can be used.

  The chloroprene latex of the present invention can provide an adhesive exhibiting better adhesive strength and high-temperature adhesive retention than conventional chloroprene latex by performing the above.

  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 gel content of the polymer, DSC, the high temperature adhesive retention and adhesive strength of the adhesive formulation were measured by the following methods and conditions.

<Measurement of gel content>
The latex was mixed with methanol to precipitate the rubber, and the rubber was taken out by filtration and vacuum drying. The rubber was immersed in toluene to a concentration of 1% by weight, mixed and dissolved in a light-shielded state with a magnetic stirrer for 20 hours, filtered through a 200 mesh wire mesh, washed with toluene, and the residue was 110. It dried at 1 degreeC for 1 hour, and made ratio of the weight of the weight and melt | dissolved rubber | gum the gel part.

<DSC measurement>
After the rubber taken out of the latex was stored at 25 ° C. or lower for 24 to 72 hours, DSC (SEIKO I & E differential differential calorimeter DSC200) was measured. The measurement was performed from −100 ° C. to 200 ° C. at a heating rate of 5 ° C./min.

<Creation of specimen>
After applying about 250 g / m ² of the adhesive composition with a brush on one side of each of No. 9 canvas (about 150 mm × 60 mm), it was dried at 70 ° C. for 3.5 minutes and pressure-bonded using a hand roller. A test piece for measurement was cut into a size of 150 mm × 25 mm.

<High temperature adhesion retention>
Immediately after bonding the test piece, the condition was adjusted for 5 minutes in an atmosphere of 80 ° C., and a 300 g weight was hung. The length peeled after 30 minutes was measured.

<Normal temperature adhesive strength>
Two minutes after bonding the test pieces, measurement was performed by pulling in a 180 ° direction at a peeling rate of 100 mm / min using a Tensilon-type tensile tester in an atmosphere of 23 ° C.

<Heat resistant adhesive strength>
Immediately after bonding the test pieces, the condition was adjusted for 5 minutes in an atmosphere at 80 ° C., and a tensile force in the direction of 180 ° was applied at a peeling rate of 100 mm / min in an atmosphere at 80 ° C. using a Tensilon type tensile tester. Measurements were made at

Example 1
The proportion of chloroprene monomer, n-dodecyl mercaptan, potassium rosinate (trade name: Longis K-25, Arakawa Chemical Industries, Ltd.), condensate of sodium naphthalenesulfonate and formaldehyde (trade name: Demol N, Kao Corporation), hydrosulfite sodium, and pure water were polymerized at 15 ° C. in a 10 L autoclave equipped with a stirrer. Polymerization was carried out by continuously dropping 0.35% by weight aqueous potassium persulfate in a nitrogen atmosphere, and when the polymerization conversion reached 63%, 2,3-dichlorobutadiene monomer was replaced with chloroprene monomer. 47 parts by weight and 100 parts by weight of n-dodecyl mercaptan were added to 100 parts by weight of chloroprene monomer. When the overall polymerization conversion rate including 2,3-dichlorobutadiene reached 90%, 0.05 parts by weight of 2,6-tertiarybutyl-4-methylphenol was added as a polymerization terminator to terminate the polymerization. . Thereafter, the solid content of the latex was adjusted to 55% by removing and concentrating unreacted monomers under reduced pressure to obtain Latex A.

ラテックスのゲル分は３１％であった。ラテックスＡ中のポリマーのＤＳＣ測定の結果、４１℃と８８℃に吸熱ピークがあった。また、ラテックス１００重量部に対し、樹脂エマルジョン、金属酸化物、増粘剤を配合して接着剤組成物を作製し、その高温接着保持力および接着強度を測定した。配合を表２に、結果を表３に示す。表３の結果より、高温接着保持力および接着強度は良好な値であった。

The gel content of the latex was 31%. As a result of DSC measurement of the polymer in latex A, there were endothermic peaks at 41 ° C and 88 ° C. Further, an adhesive composition was prepared by blending a resin emulsion, a metal oxide, and a thickener with 100 parts by weight of latex, and the high-temperature adhesive holding force and adhesive strength were measured. The formulation is shown in Table 2, and the results are shown in Table 3. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

実施例２
使用するクロロプレン単量体、２，３−ジクロロブタジエン単量体、ｎ−ドデシルメルカプタン、ロジン酸カリウム、ナフタレンスルホン酸ナトリウムとホルムアルデヒドの縮合物、ハイドロサルファイトナトリウム、及び純水を表１に示す量に変更した以外は実施例１に従って重合を実施してラテックスＢを得た。ゲル分、ＤＳＣ、高温接着保持力および接着強度の結果を表３に示す。表３の結果より、高温接着保持力および接着強度は良好な値であった。

Example 2
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out in accordance with Example 1 except that the latex B was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 3
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 with the exception that the latex C was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 4
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 with the exception that the latex D was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 5
Latex D was cured at 50 ° C. for 5 days in a gear oven, the gel content was 62%, and the high-temperature adhesive retention and adhesive strength were measured. The results are shown in Table 3. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 6
Latex D was cured in a gear oven at 50 ° C. for 10 days, the gel content was 78%, and the high-temperature adhesive retention and adhesive strength were measured. The results are shown in Table 3. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 7
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 except that the latex E was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 8
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 with the exception that the latex F was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Example 9
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 with the exception that the latex G was obtained. Table 3 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. From the results in Table 3, the high-temperature adhesive holding power and adhesive strength were good values.

Comparative Example 1
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 except that the latex a was obtained. Table 4 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. As a result of DSC measurement, there were peaks between 30-45 ° C. and 50-100 ° C., but the gel content was 0.2% by weight, the high-temperature adhesion retention was weak, and the weight dropped.

比較例２
使用するクロロプレン単量体、２，３−ジクロロブタジエン単量体、ｎ−ドデシルメルカプタン、ロジン酸カリウム、ナフタレンスルホン酸ナトリウムとホルムアルデヒドの縮合物、ハイドロサルファイトナトリウム、及び純水を表１に示す量に変更した以外は、実施例１に従って重合を実施してラテックスｂを得た。ゲル分、ＤＳＣ、高温接着保持力および接着強度の結果を表４に示す。ＤＳＣ測定の結果、３０〜４５℃、および５０〜１００℃の間にピークを有するが、ゲル分が８９重量％であり、接着強度が低かった。

Comparative Example 2
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out in accordance with Example 1 except that the latex b was obtained. Table 4 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. As a result of DSC measurement, there were peaks between 30 to 45 ° C. and 50 to 100 ° C., but the gel content was 89% by weight and the adhesive strength was low.

Comparative Example 3
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 except that the latex c was obtained. Table 4 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. As a result of DSC measurement, it has a peak at 30 to 45 ° C. and the gel content is in the range of 1 to 80% by weight (12% by weight), but there is no peak between 50 to 100 ° C., and high temperature adhesion retention Was weak and the weight dropped.

Comparative Example 4
Table 1 shows the amounts of chloroprene monomer, 2,3-dichlorobutadiene monomer, n-dodecyl mercaptan, potassium rosinate, sodium naphthalenesulfonate-formaldehyde condensate, hydrosulfite sodium and pure water used Polymerization was carried out according to Example 1 except that the latex d was obtained. Table 4 shows the results of gel content, DSC, high-temperature adhesive retention and adhesive strength. As a result of DSC measurement, there is a peak at 30 to 45 ° C., but there is no peak between 50 and 100 ° C., and the gel content is in the range of 1 to 80 wt% (18 wt%), but the adhesive strength is low. It was.

  The chloroprene latex of the present invention is widely used as a solvent-free adhesive that does not use a solvent that has an adverse effect on the global environment and the health of workers, sometimes causing a fire in the workplace, etc. Adhesive holding power and adhesive strength are good.

Claims (8)

A copolymer of chloroprene and 2,3-dichlorobutadiene, the copolymer being 6 to 135 parts by weight of 2,3-dichlorobutadiene and 1 to 80% by weight of gel based on 100 parts by weight of chloroprene. A chloroprene latex characterized in that one or more endothermic peaks exist between 30 to 45 ° C. and 50 to 100 ° C. in the DSC measurement curve of the copolymer. The chloroprene latex according to claim 1, wherein the copolymer has a gel content of 10 to 60% by weight. The chloroprene latex according to claim 1 or 2, comprising an anionic emulsifier. The chloroprene latex according to claim 3, wherein the anionic emulsifier is an alkali metal salt of rosin acid. Polymerization was started using 100 parts by weight of chloroprene monomer and 0.005 to 0.1 part by weight of n-dodecyl mercaptan. Thereafter, the polymerization conversion was 60 to 90%, with respect to 100 parts by weight of chloroprene monomer. In addition, 0.01 to 0.3 parts by weight of n-dodecyl mercaptan is added, and 6 to 54 parts by weight of 2,3-dichlorobutadiene monomer is added so as to satisfy the following formula. The manufacturing method of the chloroprene latex in any one of Claims 4-5.
(100-C) × 0.6 <X ≦ (100-C) × 1.35
(In the formula, X represents a part by weight of 2,3-dichlorobutadiene monomer to be added, and C represents a polymerization conversion rate.) 6. The method for producing a chloroprene latex according to claim 5, wherein after the latex is polymerized, the gel content is adjusted by aging by applying heat of 30 [deg.] C. or higher. A chloroprene latex composition comprising the chloroprene latex according to any one of claims 1 to 4. An adhesive composition comprising the chloroprene latex according to any one of claims 1 to 4.