JP5532580B2 - Chloroprene latex and method for producing the same - Google Patents

Description

  The present invention relates to a chloroprene latex having good adhesive properties in a wet state and excellent storage stability, a method for producing the same, and an adhesive composition using 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 Document 1 to Patent Document 2 and Non-Patent Document 1). These exhibit high adhesiveness immediately after bonding by bonding after applying and drying the adhesive.

  However, since the drying speed of water is slower than that of the solvent, it takes a long time to dry after applying the adhesive, and there is a problem that poor adhesion occurs in an undried state.

  On the other hand, there is a method in which the pH of chloroprene latex is adjusted to 7 to 10 to improve adhesive properties in a wet state (for example, Patent Documents 3 to 4). However, since the latex is destabilized by adjusting the pH to 7 to 10 and the rubber is easily precipitated, it is usually in a one-part form that can be stored for a long time, but storage stability There was a problem such as bad.

Japanese Patent Laid-Open No. 11-158327 JP-A-9-31429 JP 2001-19922 A JP 2001-19923 A JETI Vol. 44 no. 12 (88 pages)

  The present invention has been made in view of this problem, and provides an adhesive having improved adhesive strength in a wet state, and provides a chloroprene latex having good adhesive properties and storage stability.

  As a result of intensive investigations to solve the above problems under the above background, the inventor contains an alkali metal salt of rosin acid having a specific component in the latex and has a potassium content of 4000 ppm or less. And if content of sodium was 2000 ppm or less, it discovered that adhesive physical property and stability in storage were favorable, and came to complete this invention. That is, the present invention relates to an emulsifier comprising a metal salt of rosin acid having a value of (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) of 1 or more, and a chloroprene polymer and / or chloroprene copolymer. A chloroprene latex containing a polymer, having a potassium content of 4000 ppm or less and a sodium content of 2000 ppm or less.

  Hereinafter, the present invention will be described in detail.

  The chloroprene latex of the present invention contains an emulsifier composed of an alkali metal salt of rosin acid having a value of (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) of 1 or more. When an alkali metal salt of rosin acid having a value of (8,15-isopimalic acid content) / (dihydropimalic acid content) of less than 1 is used, the storage stability is poor and the adhesive strength is also low. 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.

  The content of the emulsifier is not particularly limited, but is preferably 1.5 to 3.5 parts by weight with respect to 100 parts by weight of the latex from the viewpoint of stability in the blending of the latex and adhesive properties.

  The chloroprene latex of the present invention contains a chloroprene polymer and / or a chloroprene copolymer.

  The chloroprene polymer is obtained by polymerizing a chloroprene monomer which is 2-chloro-1,3-butadiene alone. The chloroprene copolymer is obtained by polymerization using a chloroprene monomer and one or more monomers copolymerizable with chloroprene.

  Examples of monomers copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monoacrylate, Examples include polyethylene glycol monomethacrylate and glycerin monomethacrylate.

Chloroprene latex of the present invention is a content 2500~ 4000pp m of potassium and sodium content is 200~ 2000pp m. When the potassium content exceeds 4000 ppm, or when the sodium content exceeds 2000 ppm, the adhesive strength and storage stability are lowered.

  The chloroprene latex of the present invention preferably contains a strong alkaline substance in order to ensure the pH stability of the latex. Examples of the strongly alkaline substance include sodium hydroxide and potassium hydroxide.

  The chloroprene latex of the present invention may contain a stabilizer having an alkali metal salt of sulfonic acid in order to ensure the stability of the latex. Examples of the stabilizer include alkali metal salts of aliphatic sulfonic acids having an alkyl chain having 8 or less carbon atoms, such as alkali metal salts of pentane sulfonic acid and alkali metal salts of octane sulfonic acid, and compounds having these, benzene sulfone Alkali metal salts of acids, alkali metal salts of toluene sulfonic acid, alkali metal salts of butylnaphthalene sulfonic acid, alkali metal salts of aromatic sulfonic acids such as styrene sulfonate, and compounds having these aromatic sulfonates ( Alkaline metal salt of naphthalenesulfonic acid and formalin condensate, etc.) Alkyl sulfate ester salt such as alkali metal salt of lauryl sulfate, Polyoxyethylene alkyl ether sulfate alkali metal salt such as alkali metal salt of polyoxyethylene lauryl ether sulfate Unsaturated Various copolymers of alkali metal salts of sulfonic acid and copolymerizable therewith monomer having the like. Examples of the alkali metal salt of sulfonic acid 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, and an alkali metal of isoprene sulfonic acid. Examples thereof include acrylic acid, methacrylic acid, fumaric acid, maleic acid, methyl methacrylate and the like. Examples of the alkali metal salt include lithium, sodium, potassium, cesium and the like. These may be one type or two or more types. Of these, a condensate of naphthalenesulfonic acid and formaldehyde is preferable from the viewpoint of latex stability during polymerization. Although content of a stabilizer is not specifically limited, 0.5 weight part or less is preferable with respect to 100 weight part of latex from stability and adhesive physical property balance.

  The chloroprene latex of the present invention includes a chloroprene monomer, or other monomer copolymerizable with chloroprene monomer and chloroprene, and (content of 8,15-isopimalic acid) / (content of dihydropimalic acid). Can be produced by using an emulsifier composed of an alkali metal salt of rosin acid having a value of 1 or more, starting with polymerization with a potassium content of 4000 ppm or less and a sodium content of 2000 ppm or less. Moreover, when content of potassium at the time of a polymerization start and content of sodium are other than the above, it can manufacture by adding water during superposition | polymerization and / or after completion | finish of superposition | polymerization. It can also be produced by mixing a chloroprene latex having a potassium content and a sodium content other than those described above with a chloroprene latex having a potassium content of 4000 ppm or less and / or a sodium content of 2000 ppm or less.

  Here, polymerization is emulsion polymerization, and the above-mentioned monomer and emulsifier are emulsified together with a polymerization initiator, a chain transfer agent, etc., carried out at a predetermined temperature, and a polymerization terminator is added at a predetermined conversion rate. What is necessary is just to add.

  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. Although the usage-amount of a chain transfer agent is not specifically limited, 0.1-0.3 weight part is normally used with respect to 100 weight part of chloroprene monomers.

  In order to ensure the pH stability of the latex, it is preferable to use a strong alkaline substance. Examples of the strongly alkaline substance include sodium hydroxide and potassium hydroxide.

  The polymerization temperature is not particularly limited, but is preferably in the range of 10 to 30 ° C. in order to obtain good adhesive properties.

  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 85-95%.

  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 the polymerization and after the polymerization.

  After completion of the polymerization, the polymer may be concentrated in order to adjust the solid content of the latex. Concentration can be achieved by evaporating water under reduced pressure using, for example, a rotary evaporator.

  Although the chloroprene latex of the present invention can be used alone as an adhesive, it can be an adhesive composition containing a tackifier resin, a crosslinking agent, a thickener and the like listed below.

  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 adhesive composition containing the chloroprene latex of the present invention can particularly improve the adhesive properties in a wet state by adjusting the pH to 7 to 10. The pH can be adjusted by adding a pH adjusting agent or adding various emulsions or latexes having a pH of less than 10, and these can be used alone or in combination of two or more. Examples of the pH regulator include organic acids such as acetic acid, citric acid, malonic acid, methacrylic acid, malic acid, maleic acid, and oxalic acid, inorganic acids such as boric acid and phosphoric acid, and amino acids such as glycine, alanine, and glutamic acid. Examples of emulsions and latex having a pH of less than 10 include acrylic emulsions such as acrylic esters and methacrylic esters, acrylic monomers such as chloroprene monomers, styrene monomers or butadiene monomers. Synthetic rubber-based latex and the like that are copolymerized with the body can be used, but any other substance that can be arbitrarily mixed with chloroprene latex and adjust the pH can be used.

  The adhesive composition containing chloroprene latex may contain additives such as anti-aging agent, preservative, anti-freezing agent, film-forming aid, plasticizer, clay, etc., if necessary.

  The chloroprene latex of the present invention has good adhesive properties when used as an adhesive composition in which the adhesive strength in a wet state is improved by destabilizing the pH by adjusting as described above, The good physical properties can be maintained for a long time.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to only these examples.

  In addition, the storage period in an Example and a comparative example was set as the storage for 1 month at 50 degreeC as acceleration conditions equivalent to the storage for 6 months at 23 degreeC.

  Further, the value of (8,15-isopimalic acid content) ÷ (dihydropimalic acid content), potassium and sodium ion content, adhesive properties in a wet state, and storage stability were measured by the following methods.

<(8,15-Isopimaric acid content) / (dihydropimalic acid content)>
After methylation of an emulsifier composed of an alkali metal salt of rosin acid to be used, measurement by gas chromatography was carried out. From the peak area of each component, the ratio of 8,15-isopimalic acid and dihydropimalic acid [(8,15-isopimalic acid (Content) ÷ (content of dihydropimaric acid)] was calculated. In the analysis of emulsifiers for ready-made latexes, the latex was dried, dissolved in chloroform, purified by reprecipitation with hydrochloric acid-methanol, the filtrate was concentrated, methylated, and measured by gas chromatography. The ratio of 8,15-isopimalic acid and dihydropimalic acid was calculated from the peak area of each component.

Column used: DB-5 0.25 mmφ × 30 m (film thickness 1 μm)
Column temperature: 150 ° C. → 300 ° C. (30 min hold)
Temperature increase rate: 5 ° C / min
Inlet temperature: 250 ° C
Detector temperature: 250 ° C
Injection volume: 1 μl
<Ion content of potassium and sodium>
The latex was decomposed with sulfuric acid and quantified with an inductively coupled plasma emission spectrometer (ICP-AES: Optima3000DV, manufactured by PerKinElmer).

<PH>
The pH at 25 ° C. was measured with a pH meter (manufactured by Horiba, Ltd.).

<Adhesive properties in wet condition>
The latex was stirred with a magnetic stirrer, and the pH was adjusted by adding a pH adjusting agent while confirming the pH. The adherend used was a high-quality polyurethane foam (density 40 kg / m ³ ) processed into a cubic shape with 5 cm sides. This one surface (25 cm ² ) was coated with latex adjusted to have a pH of 40-80 g / m ² with a spray gun (manufactured by Anest Iwata Corporation; W-101-101G). Bonding was performed after a lapse of seconds. Bonding was performed so that the coated surface was folded in two, and whether or not the state could be maintained was determined.

<Storage stability>
The pH-adjusted latex was stored in a glass container with a lid, sealed, and stored in a gear oven at 50 ° C., and the state was periodically observed.

Example 1
Chloroprene monomer, n-dodecyl mercaptan, potassium rosinate (trade names: Bandis T-25KP, Harima Kasei Co., Ltd.) (content of 8,15-isopimalic acid) / (dihydropimalic acid) in the proportions shown in Table 1 Content) = 6.7), condensate of sodium naphthalenesulfonate and formaldehyde (trade name: Demol N, Kao Corporation), sodium hydroxide, hydrosulfite sodium, and pure water in a 10 L autoclave with a stirrer Polymerization was carried out at 15 ° C. Polymerization was carried out by continuously dropping 0.35% by weight potassium persulfate aqueous solution under a nitrogen atmosphere. The polymerization conversion was 90% and 2,6-tertiarybutyl-4-methylphenol as a polymerization terminator was added in an amount of 0.1%. The polymerization was stopped by adding 05 parts by weight. Thereafter, the solid content of the latex was adjusted to 50% by removing and concentrating unreacted monomers under reduced pressure to obtain Latex A.

ラテックスＡのｐＨをｐＨ調節剤であるホウ酸にて９に調節し、湿潤状態での接着物性の測定、および保管安定性の確認等を実施した。結果を表２に示す。表２の結果より、接着物性は良好であり、保管によるラテックスの状態変化は無かった。

The pH of latex A was adjusted to 9 with boric acid as a pH adjusting agent, and measurement of adhesive properties in a wet state and confirmation of storage stability were performed. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

実施例２
使用するロジン酸カリウムを（商品名：バンディスＴ−３４Ｋ、ハリマ化成（株）；（８，１５−イソピマル酸の含有量）÷（ジヒドロピマル酸の含有量）＝４．２）に変更しラテックスＢを得た以外は実施例１に従い接着物性および保管安定性の評価を行った。結果を表２に合わせて示す。表２の結果より、接着物性は良好であり、保管によるラテックスの状態変化は無かった。

Example 2
Latex B was obtained by changing the potassium rosinate to be used (trade name: Bandis T-34K, Harima Kasei Co., Ltd .; (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) = 4.2). The adhesive properties and storage stability were evaluated according to Example 1 except that the above was obtained. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 3
Adhesive properties and storage stability were evaluated according to Example 1 except that the pH adjuster used was changed from boric acid to glycine. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 4
The adhesive properties and storage stability were evaluated according to Example 1 except that the pH adjuster used was changed to chloroprene latex (Skyprene (registered trademark) GFL-820 (pH 2.5, manufactured by Tosoh Corporation)). The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 5
The amount of sodium hydroxide used was changed to the amount shown in Table 1 and latex C was obtained, and the adhesive properties and storage stability were evaluated according to Example 1. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 6
The amount of sodium hydroxide to be used was changed to the amount shown in Table 1 and latex D was obtained, and the adhesive properties and storage stability were evaluated according to Example 1. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 7
Evaluation of adhesive properties and storage stability according to Example 1 except that latex E was obtained by changing the monomer used from chloroprene monomer alone to chloroprene monomer and 2,3-dichlorobutadiene monomer. Went. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 8
Adhesive properties and storage stability were evaluated in accordance with Example 1 except that the amount of potassium hydroxide shown in Table 1 was used and latex F was obtained. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 9
The adhesive properties and storage stability were evaluated according to Example 1 except that sodium hydroxide was changed to the amount of potassium hydroxide shown in Table 1 and latex G was obtained. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 10
The amount of pure water was changed to the amount shown in Table 1 and latex H was obtained by adding 20 parts by weight of pure water to 100 parts by weight of chloroprene monomer charged at a polymerization conversion rate of about 30%. Adhesive properties and storage stability were evaluated. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 11
Latex I was obtained by changing the amounts of sodium naphthalene sulfonate and formalin condensate, sodium hydroxide, potassium hydroxide and pure water to the amounts shown in Table 1. The solid content when the polymerization was stopped was about 50%. Thereafter, 15 parts by weight of pure water was added to 100 parts by weight of the charged chloroprene monomer (solid content: about 47%), and adhesive properties and storage stability were evaluated. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Example 12
Latex E and Latex I were blended at 70:30, and the adhesive properties and storage stability were evaluated according to Example 1. The results are shown in Table 2. From the results shown in Table 2, the adhesive properties were good and there was no change in the latex state due to storage.

Comparative Example 1
Other than changing the potassium rosinate used to (Londis K-25, Arakawa Chemical Co., Ltd .; (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) = 0) Were evaluated for adhesive properties and storage stability according to Example 1. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior, and the latex was solidified by storage.

比較例２
使用する水酸化ナトリウムの量を表１に示す割合に変更し、ラテックスＫを得た以外は実施例１に従い接着物性および保管安定性の評価を行った。結果を表３に合わせて示す。表３の結果より、接着物性は劣り、保管によりラテックスが固化した。

Comparative Example 2
The amount of sodium hydroxide used was changed to the ratio shown in Table 1 and latex physical properties K were obtained, and the adhesive properties and storage stability were evaluated according to Example 1. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior, and the latex was solidified by storage.

Comparative Example 3
Adhesive properties and storage stability were evaluated according to Example 1 except that the sodium hydroxide used was potassium hydroxide and the amount was changed to the ratio shown in Table 1 to obtain latex L. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior, and the latex was solidified by storage.

Comparative Example 4
The latex used is chloroprene latex (Skyprene (registered trademark) LA-660 (content of 8,15-isopimalic acid) ÷ (content of dihydropimalic acid) = 0, sodium ion 1500 ppm, potassium ion 2100 ppm, manufactured by Tosoh Corporation)) The adhesive properties and storage stability were evaluated in accordance with Example 1 except that the change was made. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior, and the latex was solidified by storage.

Comparative Example 5
Latex I was evaluated for adhesive properties and storage stability according to Example 1. The results are shown in Table 3. From the results in Table 3, the adhesive properties were inferior, and the latex was solidified by storage.

Claims (6)

A chloroprene latex obtained by polymerization at a polymerization temperature of 10 to 30 ° C., and an alkali of rosin acid having a value of (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) of 1 or more 1.5 to 3.5 parts by weight of an emulsifier comprising a metal salt with respect to 100 parts by weight of the latex, and contain chloroprene polymer and / or chloroprene copolymer, the content of potassium is 2500~ 4000pp m, and, chloroprene latex, wherein the content of sodium is 200~ 2000pp m. The value of chloroprene monomer or other monomer copolymerizable with chloroprene monomer and chloroprene and (content of 8,15-isopimalic acid) ÷ (content of dihydropimalic acid) is 1 or more. using emulsifiers consisting of alkali metal salts of rosin acids, with the content of potassium 2500~ 4000pp m, and the content of sodium to initiate the polymerization at 200~ 2000pp m, polymerization at a polymerization temperature of 10 to 30 ° C. The method for producing a chloroprene latex according to claim 1. The value of chloroprene monomer or other monomer copolymerizable with chloroprene monomer and chloroprene and (content of 8,15-isopimalic acid) ÷ (content of dihydropimalic acid) is 1 or more. Using an emulsifier composed of an alkali metal salt of rosin acid, the polymerization is started under the condition that the potassium content exceeds 4000 ppm and / or the sodium content exceeds 2000 ppm . The method for producing a chloroprene latex according to claim 1 , wherein the polymerization is performed at a polymerization temperature, and water is added during and / or after the completion of the polymerization. An emulsifier composed of an alkali metal salt of rosin acid having a value of (8,15-isopimalic acid content) / (dihydropimalic acid content) of 1 or more, and a potassium content exceeding 4000 ppm, and / or Alternatively, an emulsifier comprising a chloroprene latex having a sodium content exceeding 2000 ppm and an alkali metal salt of rosin acid having a value of (8,15-isopimalic acid content) ÷ (dihydropimalic acid content) of 1 or more. and the content of potassium 2500~ 4000pp m, and / or method for producing a chloroprene latex according to claim 1 in which the content of sodium is characterized by mixing a chloroprene latex 200~ 2000pp m. An adhesive composition comprising the chloroprene latex according to claim 1. pH is 7-10, The adhesive composition of Claim 5 characterized by the above-mentioned.