JP2014114423A - Method for producing chloroprene rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method which does not cause deterioration of productivity due to separation and removal of trans-2-chloro-2-butene whose separation is difficult because of having a boiling point close to that of chloroprene rubber, and can obtain high-quality chloroprene rubber.SOLUTION: In a method for producing chloroprene rubber, a chloroprene monomer containing 0.1-5.5 wt.% trans-2-chloro-2-butene is emulsion-polymerized.

Description

  The present invention relates to a method for producing chloroprene rubber, and more particularly to a method for producing high-quality chloroprene rubber.

  Chloroprene rubber is excellent in oil resistance, heat resistance, weather resistance, chemical resistance, flame resistance, etc., and has a good balance of mechanical properties, so it is widely used in applications such as automotive parts, hoses, wire coatings, sponges, adhesives, etc. It has been. The raw material chloroprene monomer (2-chloro-1,3-butadiene) is industrially chlorinated, isomerized and dehydrochlorinated butadiene (for example, Non-Patent Document 1).

  In the production of the chloroprene monomer, by-products other than chloroprene are generated, and thus industrially used after removing impurities by distillation or the like. However, by-products that have a boiling point close to that of chloroprene monomer and are difficult to separate (for example, trans-2-chloro-2-butene) are difficult to separate from chloroprene monomer and are accompanied by some chloroprene monomer. It has been used for the production of chloroprene rubber after being highly purified by using a great deal of loss and energy, such as being discarded on the surface or increasing the number of distillations (Patent Document 1).

Japanese Patent Publication No. 40-25329

Asai Osamu, “Synthetic Rubber Overview”, Asakura Shoten, February 25, 1971, p156-159

  The present invention has been made in view of this problem, and there is no decrease in productivity due to separation and removal of trans-2-chloro-2-butene, which has a boiling point close to that of the chloroprene monomer and is difficult to separate, and The present invention relates to a production method for providing high-quality chloroprene rubber.

  As a result of intensive studies to solve the above problems, the present inventors have found that a chloroprene monomer containing a certain range of trans-2-chloro-2-butene, which has a boiling point close to that of the chloroprene monomer and is difficult to separate. It has been found that a high-quality chloroprene rubber can be obtained when used, and the present invention has been completed. That is, the present invention is a method for producing a chloroprene rubber, which comprises emulsion polymerization of a chloroprene monomer containing 0.1 to 5.5% by weight of trans-2-chloro-2-butene.

  Hereinafter, the present invention will be described in detail.

  In the production method of the present invention, a chloroprene rubber is produced by emulsion polymerization of a chloroprene monomer containing 0.1 to 5.5% by weight of trans-2-chloro-2-butene.

  The chloroprene monomer used in the production method of the present invention is 2-chloro-1,3-butadiene. The chloroprene rubber is obtained by polymerizing a chloroprene monomer, and if necessary, another monomer copolymerizable with the chloroprene monomer may be used in combination. If trans-2-chloro-2-butene contained in the chloroprene monomer is less than 0.1% by weight, it is difficult to separate 2-chloro-1,3-butadiene and trans-2-chloro-2-butene. The purification process is complicated, and a large amount of 2-chloro-1,3-butadiene is lost. On the other hand, when 2-chloro-1,3-butadiene exceeds 5.5% by weight, the quality (particularly compound physical properties) of the obtained chloroprene polymer is critically lowered. The trans-2-chloro-2-butene contained is preferably 0.1 to 5.0% by weight in order to maintain physical properties.

  Other monomers copolymerizable with the chloroprene monomer are not particularly limited. For example, 2,3-dichloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxy Examples include propyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycerin monomethacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, and 2-methacryloyloxyethyl succinic acid. The amount of the other monomer copolymerizable with chloroprene is not particularly limited, but may be 20 parts by weight or less with respect to 100 parts by weight of the chloroprene monomer.

  The chloroprene rubber can be emulsion-polymerized using a chloroprene monomer alone or a chloroprene monomer and another monomer copolymerizable therewith using an emulsifier and a chain transfer agent.

  Emulsion polymerization may be carried out by emulsifying the above-mentioned monomer and emulsifier together with a polymerization initiator, a chain transfer agent and the like at a predetermined temperature and adding a polymerization terminator at a predetermined conversion rate. If necessary, it may further contain one or more other monomers copolymerizable with the chloroprene monomer.

  As the emulsifier, for example, an alkali metal salt of rosin acid, an alkyl sulfate salt, an alkyl sulfonate, or the like can be used, but an alkali metal salt of rosin acid is generally used.

  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. Usually, these are mixed together with the monomer to be polymerized and reacted, but they may be added alone during the reaction. When an alkali metal salt of rosin acid is used as the emulsifier, it is generally used in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer.

  The polymerization temperature is not particularly limited, but is generally in the range of 10 to 55 ° C.

  Although the completion | finish time of superposition | polymerization is not specifically limited, In order to obtain productivity and favorable adhesive property, it is common that the polymerization conversion rate of a monomer shall be 50 to 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.

  Since the chloroprene rubber obtained by the production method of the present invention is as high quality as the chloroprene rubber obtained by the usual polymerization method, the vulcanizing agent and vulcanization are carried out by a kneader such as a roll, kneader or Banbury as in the conventional case. It can be mixed with accelerators, reinforcing agents, fillers, plasticizers, anti-aging agents, etc. to create a compound, and after molding into a shape according to the purpose, it can be obtained by a normal polymerization method. A vulcanizate having performance equivalent to that of the chloroprene rubber to be obtained can be obtained.

  In the production method of the present invention, energy and waste can be reduced. Further, the chloroprene rubber obtained by the production method of the present invention can obtain a vulcanized rubber in the same manner as the conventional chloroprene rubber. Sulfur rubber has almost the same mechanical properties as conventional chloroprene rubber.

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

<Raw rubber properties>
The Mooney viscosity of the chloroprene polymer (rubber) in the examples was measured and evaluated according to JIS K6388 (1995 edition).

<Compound properties>
To confirm the properties of the unvulcanized compounded rubber, mill shrinkage and extrusion characteristics were measured. Mill shrinkage was obtained by winding 750 g of a chloroprene rubber compound around an 8-inch open roll adjusted to a guide width of 20 cm and 40 ° C., cutting out when the gap became uniform 2 mm, and before and after standing at 23 ° C. for 3 hours. It was calculated as a change rate (%) of the sheet length. Extrusion characteristics were measured with a capillary rheometer (ARC2020, manufactured by Alpha Technologies) using a die with L / D = 1.5 mm / 1.5 mm and a shear rate of 300 (1 / sec) at a temperature of 70 ° C. Judgment was made from the die swell value (%).

<Vulcanized properties>
The hardness of the vulcanizate characteristic was measured according to JIS K6253 (1997 edition). The elongation at break, rupture strength, and 100% stress of the vulcanizate were evaluated according to JIS K6251 (1993 edition) using a dumbbell-shaped No. 3 type test piece at a pulling speed of 500 mm / min.

Reference Example 1 (Production of chloroprene rubber by conventional polymerization method)
According to the polymerization formulation shown in Table 1, 2-chloro-1,3-butadiene 100 parts by weight (trans-2-chloro-2-butene content: less than 0.1% by weight), n-dodecyl mercaptan 0.2 parts by weight Was added to a 10 L autoclave equipped with a stirrer, and an emulsion of 3.5 parts by weight of potassium rosinate, 0.7 parts by weight of a formaldehyde condensate of sodium naphthalene sulfonate, 0.25 parts by weight of sodium hydroxide, and 100 parts by weight of distilled water was added. It was added thereto, and after sufficiently purging with nitrogen, it was emulsified by stirring. Polymerization was started by continuous addition of a 0.2 wt% potassium persulfate aqueous solution while adding a 3 wt% sodium hydrosulfite aqueous solution and controlling the jacket temperature so that the inside of the polymerization vessel was kept constant at 40 ° C.

  When the conversion ratio to all monomers reaches 65%, 0.02 part by weight of phenothiazine is dissolved in toluene and emulsified with an aqueous sodium dodecylbenzenesulfonate solution, and 0.05 weight of N, N-diethylhydroxylamine Part of the mixture was added as a terminator to terminate the polymerization.

  The remaining unreacted monomer was removed by a vacuum steam stripping method, the polymer was precipitated by freeze-coagulation of the obtained latex, washed with water, and dried with hot air to obtain chloroprene rubber.

  The raw rubber Mooney viscosity of the obtained chloroprene rubber is shown in Table 1.

得られたクロロプレンゴムを表２に示す配合に従い３．６Ｌバンバリーで混練を行い、コンパウンドを作製した。そのコンパウンドを１６０℃にて２０分間プレス加硫することにより加硫ゴムシートを得て、加硫物特性を測定した。その結果を表１に示す。

The obtained chloroprene rubber was kneaded in a 3.6 L Banbury according to the formulation shown in Table 2 to prepare a compound. The compound was press vulcanized at 160 ° C. for 20 minutes to obtain a vulcanized rubber sheet, and the vulcanizate characteristics were measured. The results are shown in Table 1.

参考例２（従来の重合方法によるクロロプレンゴムの製造）
表１に示す重合処方に従い、２−クロロ−１，３−ブタジエン９３重量部、２，３−ジクロロ−１，３−ブタジエン７重量部、ｎ−ドデシルメルカプタン０．２２２重量部に変更した以外は参考例１と同様の方法にて重合を行い、クロロプレンゴムを得た。

Reference Example 2 (Production of chloroprene rubber by conventional polymerization method)
According to the polymerization formulation shown in Table 1, except that it was changed to 93 parts by weight of 2-chloro-1,3-butadiene, 7 parts by weight of 2,3-dichloro-1,3-butadiene, and 0.222 parts by weight of n-dodecyl mercaptan. Polymerization was carried out in the same manner as in Reference Example 1 to obtain a chloroprene rubber.

  The raw rubber Mooney viscosity of the obtained chloroprene rubber and the results of the vulcanizate properties evaluated by the same method as in Reference Example 1 are shown in Table 1.

Example 1
Polymerization was carried out according to the polymerization formulation shown in Table 1 according to Reference Example 1, except that 100 parts by weight of 2-chloro-1,3-butadiene (trans-2-chloro-2-butene content: 1% by weight) was obtained. Got rubber.

  The raw rubber Mooney viscosity of the obtained chloroprene rubber and the results of the vulcanizate properties evaluated by the same method as in Reference Example 1 are shown in Table 1. The physical properties were almost the same as in Reference Example 1.

Example 2
Polymerization was carried out according to the polymerization formulation shown in Table 1 according to Reference Example 1, except that 100 parts by weight of 2-chloro-1,3-butadiene (trans-2-chloro-2-butene content: 4.5% by weight) was used. A chloroprene rubber was obtained.

  The raw rubber Mooney viscosity of the obtained chloroprene rubber and the results of the vulcanizate properties evaluated by the same method as in Reference Example 1 are shown in Table 1. The physical properties were almost the same as in Reference Example 1.

Example 3
Reference was made except that 93 parts by weight of 2-chloro-1,3-butadiene (trans-2-chloro-2-butene content: 5% by weight) and 7 parts by weight of 2,3-dichloro-1,3-butadiene were used. Polymerization was carried out according to the polymerization formulation shown in Table 1 according to Example 2 to obtain chloroprene rubber.

  Table 1 shows the raw material rubber Mooney viscosity of the obtained chloroprene rubber and the results of vulcanizate properties evaluated by the same method as in Reference Example 2. The physical properties were almost the same as in Reference Example 2.

Comparative Example 1
Polymerization was carried out according to the polymerization formulation shown in Table 1 according to Reference Example 1, except that 100 parts by weight of 2-chloro-1,3-butadiene (trans-2-chloro-2-butene content: 6% by weight) was obtained. Got rubber.

  The raw rubber Mooney viscosity of the obtained chloroprene rubber and the results of the vulcanizate properties evaluated by the same method as in Reference Example 1 are shown in Table 1. Compared to Reference Example 1, the polymerization time was slightly longer, the compound shrinkage and die swell were large, and the strength of the vulcanizate was inferior.

Comparative Example 2
Reference was made except that 93 parts by weight of 2-chloro-1,3-butadiene (trans-2-chloro-2-butene content: 7% by weight) and 7 parts by weight of 2,3-dichloro-1,3-butadiene were used. Polymerization was carried out according to the polymerization formulation shown in Table 1 according to Example 2 to obtain chloroprene rubber.

  Table 1 shows the raw material rubber Mooney viscosity of the obtained chloroprene rubber and the results of vulcanizate properties evaluated by the same method as in Reference Example 2. Compared with Reference Example 2, the polymerization time was slightly longer, the compound shrinkage and die swell were large, and the strength of the vulcanizate was inferior.

  The chloroprene rubber of the present invention has a performance equivalent to that of a chloroprene rubber obtained by a normal polymerization method, and thus is widely used in the rubber product field.

Claims (4)

A method for producing a chloroprene rubber, comprising emulsion-polymerizing a chloroprene monomer containing 0.1 to 5.5% by weight of trans-2-chloro-2-butene. The method for producing a chloroprene rubber according to claim 1, wherein the chloroprene monomer is 2-chloro-1,3-butadiene. The method for producing chloroprene rubber according to claim 1 or 2, wherein another monomer copolymerizable with chloroprene monomer is used in an amount of 20 parts by weight or less based on 100 parts by weight of chloroprene. The method for producing a chloroprene rubber according to claim 3, wherein the other monomer copolymerizable with the chloroprene monomer is 2,3-dichlorobutadiene.