JP2016160295A - Chloroprene latex, manufacturing method thereof and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chloroprene latex good in adhesive physical property in wet state and also good in storage stability.SOLUTION: There are provided chloroprene latex containing an emulsifier of an alkali metal salt of carboxylic acid and a polyoxyalkylene derivative represented by the following general formula (1) of 0.1 to 0.5 pts.wt. based on 100 pts.wt. of the chloroprene latex, a manufacturing method and applications thereof. HO(CHCXHO)m(CHCYHO)nH (1), where X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more and n represents 1 or more of an integer.SELECTED DRAWING: None

Description

  The present invention relates to a chloroprene latex that exhibits adhesive strength without drying water and a method for producing the same.

  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 resistance was low.

  In addition, as shown in Patent Documents 3 and 4, when an emulsifier composed of a metal salt of rosin acid is used, the stability of the latex is reduced by dehydrochlorination during storage of chloroprene rubber or by lowering the pH when the adhesive is blended. Decreased, resulting in problems such as precipitation of rubber.

  There is a method of making good use of this feature and adjusting the pH with an amino acid such as glycine to improve adhesive properties in a wet state (for example, Patent Document 5).

  However, although it is in a wet state, some drying is required before bonding, and workability is inferior compared to solvent-based adhesives. Also, the adhesive properties were not sufficient.

JP-A-6-287360 JP 11-335491 A Japanese Patent Publication No.51-39262 Japanese Patent Laid-Open No. 51-136733 JP 2001-19922 A

  The present invention has been made in view of this problem, and the purpose of the chloroprene latex containing an emulsifier of an alkali metal salt of a carboxylic acid is to improve workability by improving the adhesive strength in a wet state. The present invention provides a chloroprene latex that minimizes pH drop during storage and a method for producing the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the chloroprene latex containing an emulsifier of an alkali metal salt of a carboxylic acid contains a polyoxyalkylene derivative having a specific structure. It has been found that the adhesive strength in a wet state is improved to improve workability, and further, the pH drop during storage is minimized. That is, the present invention includes a chloroprene latex characterized by containing 0.1 to 0.5 parts by weight of an emulsifier of an alkali metal salt of a carboxylic acid and a polyoxyalkylene derivative in 100 parts by weight of the chloroprene latex, An adhesive composition containing the same.

  Hereinafter, the present invention will be described in detail.

  The chloroprene latex of the present invention contains 0.1 to 0.5 parts by weight of an emulsifier of an alkali metal salt of a carboxylic acid and a polyoxyalkylene derivative represented by the following general formula (1) in 100 parts by weight of the chloroprene latex. It is a waste.

_{HO (CH 2 CXHO) m (} CH 2 CYHO) nH (1)
(In the formula, X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more, and n represents an integer of 1 or more.)
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 can be copolymerized with the chloroprene monomer as required. A mer may be used. Examples of the monomer copolymerizable with the chloroprene monomer include 2,3-dichloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol mono Examples include acrylate, polyethylene glycol monomethacrylate, glycerin monomethacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, 2-methacryloyloxyethyl succinic acid, and the like. What is obtained by using 20 weight part or less with respect to 100 weight part of a weight body is mention | raise | lifted.

  The chloroprene latex of the present invention can improve adhesive properties by adjusting pH by including an emulsifier of an alkali metal salt of a carboxylic acid. The content of this emulsifier is not particularly limited, but is preferably 1.5 to 3.5 parts by weight in 100 parts by weight of chloroprene latex in view of stability in blending of latex and balance with adhesive properties. Examples of emulsifiers for alkali metal salts of carboxylic acid include alkali metal salts of rosin acid, alkali metal salts of fatty acids, alkali metal salts of alkenyl succinic acid, and polymer compounds of alkali metal salts of polycarboxylic acid. can give. 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 polymerization stability and adhesive performance, an alkali metal salt of rosin acid is preferred.

  The polyoxyalkylene derivative represented by the following general formula (1) contained in the chloroprene latex of the present invention has a polyoxyalkylene structure, such as polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, etc. Can be given.

_{HO (CH 2 CXHO) m (} CH 2 CYHO) nH (1)
(In the formula, X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more, and n represents an integer of 1 or more.)
The molecular weight of the polyoxyalkylene derivative is not particularly limited, but it is preferably 15,000 or less because the viscosity of the latex increases and the spray coating property may decrease as the molecular weight increases.

  The chloroprene latex of the present invention needs to contain 0.1 to 0.5 parts by weight of the polyoxyalkylene derivative represented by the general formula (1) in 100 parts by weight of the latex. When the amount is less than 0.1 part by weight, the effect of addition is not observed, and when the amount exceeds 0.5 part by weight, the adhesive properties are reduced. In order to further improve the adhesive properties, it is preferable to include 0.2 to 0.4 parts by weight.

  The chloroprene latex of the present invention may contain other additives such as an antioxidant, a pH adjuster, a filler, a thickener and the like as long as the object can be achieved.

  As a method for producing the chloroprene latex of the present invention, for example, in the presence of an emulsifier of an alkali metal salt of a carboxylic acid, a chloroprene monomer or a monomer copolymerizable with this monomer is polymerized. In this case, a polyoxyalkylene derivative represented by the following general formula (1) is added.

_{HO (CH 2 CXHO) m (} CH 2 CYHO) nH (1)
(In the formula, X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more, and n represents an integer of 1 or more.)
The amount of the emulsifier composed of an alkali metal salt of carboxylic acid is not particularly limited, but in order to ensure the stability of the polymerization and latex, 3.0 to 6.0 parts by weight with respect to 100 parts by weight of the monomer. preferable.

  The polyoxyalkylene derivative represented by the general formula (1) may be used in an amount such that the amount in the latex is 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the latex. A method of adding the amount after completion of the polymerization can be mentioned. Moreover, when adding a solid thing at normal temperature, you may dilute with water and add after adding it.

  The polymerization method is not particularly limited, and for example, chloroprene monomer, or chloroprene monomer and another monomer copolymerizable with this monomer may be subjected to radical emulsion polymerization. Emulsion polymerization may be carried out by emulsifying the above-mentioned monomer and emulsifier together with a polymerization initiator, a chain transfer agent, etc. at a predetermined temperature, and adding a polymerization terminator at a predetermined conversion rate.

  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, sulfur, etc. Among these, n-dodecyl mercaptan is preferable from the viewpoint of odor and workability, and its use The amount is preferably 0.01 to 0.2 parts by weight with respect to 100 parts by weight of the chloroprene monomer.

  The polymerization temperature is not particularly limited and can be carried out in the range of 0 to 60 ° 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, the above-mentioned emulsifier may be further added during the polymerization and after the completion of the polymerization.

  The chloroprene latex of the present invention can be used as an adhesive that can be adhered in a wet state by adjusting the pH to 8.0 to 10.0. The adhesive composition of the present invention contains the chloroprene latex, and in addition, a tackifier resin and a crosslinking agent may be added.

  The tackifying resin is not particularly limited, and examples thereof include phenol resins, terpene resins, rosin derivative resins, acrylic esters, methacrylic esters, petroleum hydrocarbons, and the like, for example, polymerized rosin, rosin modified Resin, rosin modified phenolic resin, rosin ester, alkylphenol resin, terpene resin, terpene phenol, hydrogenated rosin, pentaerythritol ester of hydrogenated rosin, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic Acid 2-dimethylaminoethyl, petroleum resin, coumarone resin and the like are mixed.

  As the cross-linking agent, any compound that can be uniformly mixed with chloroprene latex can be used. For example, an epoxy resin, a polyisocyanate compound, or the like can be used.

  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. 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 improves the workability by improving the adhesive strength in a wet state, and further minimizes the pH drop during storage.

  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 pH, storage stability and adhesive properties of the latex were measured by the following methods.

<PH>
The pH of the latex at 23 ° C. was measured with a pH meter (manufactured by Horiba, Ltd.).

<Adhesive properties ((Adhesive strength in wet condition)>
Stir the latex with a magnetic stirrer, mix 20 parts by weight of acrylic emulsion (Acronal YS511ap, manufactured by BASF Japan) as a tackifier resin with respect to 100 parts by weight of the latex, add pH adjuster while checking the pH, and adjust the pH. Adjusted. The adherend used was a polyurethane foam (density 40 kg / m ³ ) processed into a cubic shape with sides of 5 cm. Apply a latex with pH adjusted to 40-100 g / m ² by spray gun (Anest Iwata Co., Ltd .; W-101-101G) on one surface (25 cm ² ) of each of the ^two foams. Was pasted together. Bonding was performed by overlapping the application surfaces of the two foams and pressing them by hand for 5 seconds. Immediately after that, it was confirmed whether or not the weight could be kept hanging.

Example 1
The proportion of chloroprene monomer, n-dodecyl mercaptan, PEG400 (polyethylene glycol, molecular weight 400: manufactured by Daiichi Kogyo Seiyaku), potassium rosinate (trade name: Longis K-25, manufactured by Arakawa Chemical Industries, Ltd.) ), Sodium naphthalene sulfonate and formaldehyde condensate (trade name: Demol N, manufactured by Kao Corporation), sodium hydroxide, hydrosulfite sodium, and pure water are polymerized at 20 ° C. in a 10 L autoclave with a stirrer, and chloroprene Latex was made. Polymerization was carried out by continuously dropping a 0.35% by weight aqueous potassium persulfate solution under a nitrogen atmosphere, and 2,6-tertiarybutyl-4 as a polymerization terminator when the polymerization conversion reached about 90%. -The polymerization was stopped by adding 0.05 parts by weight of methylphenol. Thereafter, the solid content of the latex was adjusted to 50% by removing and concentrating unreacted monomers under reduced pressure to obtain Latex A.

  Glycine was added to adjust the pH of latex A to 9.0, and the adhesive properties and storage stability were evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 2
Adhesion was carried out in the same manner as in Example 1 except that the monomers used were chloroprene monomer and 2,3-dichloro-1,3 butadiene monomer, and the polymerization temperature was changed to 15 ° C. to obtain latex B. The physical properties and storage stability were evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 3
The adhesive properties and storage stability were evaluated in the same manner as in Example 1 except that the acid to be added was changed from glycine to boric acid and the pH was 8.5. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 4
The adhesive properties and storage stability were evaluated in the same manner as in Example 1 except that the amount of PEG 400 used was changed to the amount shown in Table 1 to obtain Latex C. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 5
The adhesive properties and storage stability were evaluated in the same manner as in Example 1 except that the amount of PEG 400 used was changed to the amount shown in Table 1 and latex D was obtained. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 6
Polymerization was carried out without using PEG 400 (latex a). Adhesive properties and storage stability were evaluated according to Example 1 except that 0.25 part by weight of PEG 400 was added to obtain latex E after completion of the polymerization. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 7
Adhesive properties and storage stability were the same as in Example 6 except that the polyoxyalkylene derivative added was changed to 0.3 parts by weight of PEG200 (polyethylene glycol, molecular weight 200: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to obtain latex F. Was evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 8
The adhesive properties and storage stability were the same as in Example 1 except that the polyoxyalkylene derivative used was changed to 0.3 parts by weight of PEG1000 (polyethylene glycol, molecular weight 1000: manufactured by Daiichi Kogyo Seiyaku) and latex G was obtained. Was evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 9
Adhesive properties and storage stability were the same as in Example 6 except that the polyoxyalkylene derivative to be added was changed to 0.3 parts by weight of PEG2000 (polyethylene glycol, molecular weight 2000: manufactured by Daiichi Kogyo Seiyaku) and latex H was obtained. Sexuality was evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 10
Adhesive properties and storage stability were the same as in Example 1 except that latex I was obtained by changing the polyoxyalkylene derivative used to 0.3 parts by weight of PEG 11000 (polyethylene glycol, molecular weight 11000: manufactured by Daiichi Kogyo Seiyaku). Was evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 11
Except that the polyoxyalkylene derivative used was changed to 0.3 parts by weight of Emulgen PP-290 (polyoxyethylene polyoxypropylene ether, average molecular weight of about 10,000: manufactured by Kao Corporation), and latex J was obtained. In the same manner as in No. 1, the adhesive properties and storage stability were evaluated. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Example 12
Except that the polyoxyalkylene derivative to be added was changed to 0.25 parts by weight of Emulgen PP-290 (polyoxyethylene polyoxypropylene ether, average molecular weight of about 10,000: manufactured by Kao Corporation), and latex K was obtained. The adhesive properties and storage stability were evaluated in the same manner as in 6. The results are shown in Table 2. From the results in Table 2, the adhesive properties were good.

Comparative Example 1
Latex a was evaluated for adhesive properties and storage stability in the same manner as in Example 1. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

Comparative Example 2
The adhesive properties and storage stability were evaluated in the same manner as in Example 1 except that the amount of PEG 400 used was changed to the amount shown in Table 1 and latex b was obtained. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

Comparative Example 3
The amount of PEG 400 to be added was changed to the amount shown in Table 1 and latex physical properties were evaluated in the same manner as in Example 1 except that latex c was obtained. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

Comparative Example 4
The polyoxyalkylene derivative used was changed to PEG 20000 (polyethylene glycol, molecular weight 20,000: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), changed to the amount shown in Table 1, and latex d was obtained in the same manner as in Example 6. The adhesive properties and storage stability were evaluated. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

Comparative Example 5
The adhesive properties and storage stability were evaluated in the same manner as in Example 6 except that the polyoxyalkylene derivative used was changed to Emulgen PP-290 and latex e was obtained. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

Comparative Example 6
The amount of emulgen PP-290 to be added was changed to the amount shown in Table 3, and latex physical properties were evaluated in the same manner as in Example 6 except that latex e was obtained. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior.

  The chloroprene latex of the present invention is used for adhesive applications and widely used in the rubber product field.

Claims (4)

A chloroprene latex comprising 0.1 to 0.5 parts by weight of an emulsifier of an alkali metal salt of a carboxylic acid and a polyoxyalkylene derivative represented by the following general formula (1) in 100 parts by weight of chloroprene latex .
_{HO (CH 2 CXHO) m (} CH 2 CYHO) nH (1)
(In the formula, X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more, and n represents an integer of 1 or more.) The chloroprene latex according to claim 1, wherein the emulsifier of the alkali metal salt of carboxylic acid is an alkali metal salt of rosin acid. When polymerizing a chloroprene monomer or a chloroprene monomer and a monomer copolymerizable with the monomer in the presence of an emulsifier of an alkali metal salt of a carboxylic acid, The chloroprene according to claim 1 or 2, wherein the polyoxyalkylene derivative represented by the following general formula (1) is added at least once from the start to the end of the polymerization or after the end of the polymerization. A method for producing latex.
_{HO (CH 2 CXHO) m (} CH 2 CYHO) nH (1)
(In the formula, X and Y represent hydrogen or an alkyl chain having 1 to 2 carbon atoms, m represents 0 or more, and n represents an integer of 1 or more.) An adhesive composition comprising the chloroprene latex according to claim 1 or 2 and having a pH of 8 to 10.