JP4281587B2 - Production method of chloroprene rubber - Google Patents

Description

  The present invention relates to a method for producing chloroprene rubber. More specifically, the present invention relates to a method for producing a chloroprene rubber having excellent productivity because it can increase the production amount per batch in emulsion polymerization and can be polymerized in a polymerization time substantially equal to that in the past.

  Chloroprene rubber is used in a wide range of applications because of a good balance of physical properties among various synthetic rubbers.

  The main production method of chloroprene rubber includes batch polymerization by emulsion polymerization. Chloroprene has two double bonds in the monomer, and when polymerized to a high conversion rate, it crosslinks to become a gel polymer. Therefore, in general grades, the polymerization is stopped at a conversion rate of about 70%. In addition, gelation is suppressed. Therefore, not only the unreacted monomer needs to be removed in the next step, but the production amount per batch is insufficient, and improvement has been demanded.

  On the other hand, an attempt was made to increase the production amount by reducing the amount of water, which is a medium for emulsion polymerization, and increasing the amount of monomer charged. In order to keep the latex at the set temperature, it is necessary to reduce the polymerization rate, and although the production amount is increased, the production time is extended, and as a result, the productivity is lowered.

  Further, from the difference in specific gravity between the monomer and polymer of chloroprene, the specific gravity in the system increases and the liquid volume decreases as the polymerization proceeds. For example, even when the polymerization vessel volume is completely filled at the start of polymerization, a space is generated in the polymerization vessel at the end of polymerization, so it has been considered that there is room for improvement in production per batch.

  Furthermore, use of a polymerization vessel space that expands as the polymerization progresses has been proposed by a polymerization method in which a part of the reaction medium and the monomer mixture is added during the polymerization (see Patent Document 1). However, since the reaction medium is added together with the monomer mixture, the productivity is not sufficiently improved.

  Accordingly, there has been a demand for a production method with improved productivity in which polymerization can be performed at a rate almost equal to that of a normal polymerization method, and production per batch increases when polymerization is stopped at the same conversion rate. .

JP-A-8-109210

  The present invention has been made in view of the above-mentioned problems, and its purpose is to increase the production amount per batch in emulsion polymerization and to perform polymerization at a rate substantially equal to that of a normal polymerization method. Another object is to provide a method for producing chloroprene rubber having excellent productivity.

  As a result of intensive studies in order to solve the above-mentioned problems, the present inventors, as a result of emulsion polymerization of chloroprene or a comonomer copolymerizable with chloroprene, in the middle of polymerization, a mixture of chloroprene, a chain transfer agent, and if necessary, a comonomer. It was found that by continuing the polymerization while being added, a chloroprene rubber having excellent productivity and a quality equivalent to that of a normal polymerized product can be obtained.

  That is, in the emulsion polymerization of chloroprene rubber, the present invention provides a simple substance comprising 2-chloro-1,3-butadiene and a chain transfer agent when the polymerization conversion rate relative to the monomer mixture at the start of polymerization is 15 to 60%. A monomer mixture or a monomer mixture composed of at least one comonomer copolymerizable with 2-chloro-1,3-butadiene, 2-chloro-1,3-butadiene and a chain transfer agent is added. The monomer mixture added during the polymerization is 2 to 20 parts by weight with respect to 100 parts by weight of the monomer mixture at the start of the polymerization, and is added at a rate of 0.02 to 2 parts by weight / minute. The present invention relates to a method for producing a chloroprene rubber.

  Hereinafter, the present invention will be described in detail.

  In the emulsion polymerization of chloroprene rubber, the method of the present invention is a simple process comprising 2-chloro-1,3-butadiene and a chain transfer agent when the polymerization conversion rate relative to the monomer mixture at the start of polymerization is 15 to 60%. Polymerization is carried out by adding a monomer mixture or a monomer mixture comprising at least one comonomer copolymerizable with 2-chloro-1,3-butadiene, 2-chloro-1,3-butadiene and a chain transfer agent. Is what you do.

  When the addition is started at a polymerization conversion ratio of less than 15% with respect to the monomer mixture at the start of polymerization, the increase in latex viscosity is large and it is difficult to remove the heat of polymerization. Reduction is required and productivity is reduced. Moreover, since the space in the polymerization vessel that expands from the progress of polymerization is small at a low conversion rate, the increase in production is not sufficient, which is not preferable. On the other hand, if the addition is started at a polymerization conversion rate exceeding 60%, the time until the termination of the polymerization is short. Therefore, in order to sufficiently increase the production amount, it is necessary to increase the addition rate of the monomer mixture. Since it is difficult to remove the heat of polymerization that increases with an increase in the amount of the polymer, it is not preferable because it is necessary to reduce the polymerization rate in order to maintain the polymerization at the set temperature, and the productivity is lowered. In addition, the stability of the resulting latex is impaired.

  The monomer mixture added during the polymerization is a monomer mixture comprising 2-chloro-1,3-butadiene and a chain transfer agent, or 2-chloro-1,3-butadiene, 2-chloro-1,3- A monomer mixture comprising at least one comonomer copolymerizable with butadiene and a chain transfer agent.

  In the monomer mixture added during the polymerization, a chain transfer agent is necessary to adjust the molecular weight of the resulting chloroprene rubber, and as the chain transfer agent, if it is a compound used for general radical polymerization, Although it does not limit, For example, alkyl mercaptans, such as n-dodecyl mercaptan, t-dodecyl mercaptan, octyl mercaptan, xanthogen sulfide, benzyl iodide, iodoform, etc. are mentioned, It uses individually or in 2 or more types. The amount of the chain transfer agent is not particularly limited as long as it is an amount used in general radical polymerization for adjusting the molecular weight, but the molecular weight of the obtained polymer is set as intended. In order to prevent the formation of a crosslinked polymer structure and to enable processing and molding as a chloroprene rubber, the content is preferably 0.1 to 1 part by weight, and more preferably 0.15 to 0.3 part by weight.

  The monomer mixture added during the polymerization contains at least one comonomer copolymerizable with 2-chloro-1,3-butadiene in order to improve the performance of the resulting chloroprene rubber. Also good. The at least one comonomer copolymerizable with 2-chloro-1,3-butadiene is not particularly limited as long as it is a monomer capable of radical polymerization. For example, acrylonitrile, methacrylonitrile, vinylidene chloride, etc. Monovinyl compounds, aromatic vinyl compounds such as styrene and α-methylstyrene, unsaturated group-containing carboxylic acids such as acrylic acid and methacrylic acid, unsaturated group-containing carboxylic esters such as acrylic acid esters and methacrylic acid esters, isoprene , 1,3-butadiene, 1-chloro-1,3-butadiene, conjugated diene compounds such as 2,3-dichloro-1,3-butadiene and the like can be used, and these can be used alone or in combination of two or more. . Of these, 1-chloro-1,3-butadiene and 2,3-dichloro-1,3-butadiene are easily copolymerized with 2-chloro-1,3-butadiene, and the resulting chloroprene rubber is improved. This is particularly preferable because of its high quality effect.

  In a monomer mixture comprising 2-chloro-1,3-butadiene, at least one comonomer copolymerizable with 2-chloro-1,3-butadiene, and a chain transfer agent, 2-chloro-1,3-butadiene is used. The ratio of butadiene and at least one comonomer copolymerizable with 2-chloro-1,3-butadiene is not particularly limited as long as it is a copolymerizable amount ratio, but the characteristics as chloroprene rubber are not limited. In order to maintain, the weight ratio is preferably 25/75 to 99/1, and more preferably 80/20 to 99/1 in order to exert the characteristics of the chloroprene rubber strongly.

  In the method of the present invention, 2 to 20 parts by weight of a monomer mixture is added during polymerization at a rate of 0.02 to 2 parts by weight per 100 parts by weight of the monomer mixture at the start of polymerization. is there.

  When the addition amount of the monomer mixture is less than 2 parts by weight, the production amount is not increased sufficiently, which is not preferable. On the other hand, when the amount exceeds 20 parts by weight, the space for the polymerization vessel that expands as the polymerization progresses is not sufficient, so it is necessary to reduce the amount charged at the start of polymerization to secure the polymerization vessel space, and to improve productivity. Not efficient in terms of improvement. In addition, since the efficiency of productivity improvement is the most excellent, Preferably it is 5-15 weight part.

  When the addition rate of the monomer mixture is less than 0.02 parts by weight / minute, the amount of the monomer mixture to be added is small, which is not preferable because the production amount is not increased sufficiently. On the other hand, if it exceeds 2 parts by weight / min, it will be difficult to remove the heat of polymerization that increases with a rapid increase in monomer, and therefore it is necessary to reduce the polymerization rate in order to keep the polymerization at the set temperature. Since it falls, it is not preferable. In addition, the stability of the resulting latex is impaired. In order to facilitate the polymerization rate control, the amount is preferably 0.05 to 2 parts by weight / minute.

  In the emulsion polymerization of the chloroprene rubber of the present invention, the monomer mixture at the start of polymerization is a monomer mixture comprising 2-chloro-1,3-butadiene and a chain transfer agent, or 2-chloro-1,3-butadiene. , A monomer mixture comprising at least one comonomer copolymerizable with 2-chloro-1,3-butadiene and a chain transfer agent, and those exemplified above can be applied. The comonomer or chain transfer agent added during the polymerization may be different from the comonomer or chain transfer agent at the start of polymerization.

  In the monomer mixture at the start of polymerization comprising 2-chloro-1,3-butadiene, at least one comonomer copolymerizable with 2-chloro-1,3-butadiene, and a chain transfer agent, 2-chloro- The ratio of 1,3-butadiene and at least one comonomer copolymerizable with 2-chloro-1,3-butadiene is not particularly limited as long as it is a copolymerizable amount ratio, but can be obtained. The weight ratio is preferably 70/30 to 99/1 in order to maintain the chloroprene composition ratio in the copolymer and maintain the characteristics as a chloroprene rubber, and 80/20 in order to exert the characteristics as a chloroprene rubber strongly. -99/1 is more preferred.

  In the method of the present invention, the monomer mixture is mixed with an aqueous emulsifying dispersant solution at the start of polymerization to form an emulsion, and polymerization is allowed to proceed by adding a polymerization initiator thereto. The emulsifying dispersant is not particularly limited as long as it is a surfactant generally used for emulsion polymerization, and examples thereof include anionic emulsifiers such as carboxylate type, sulfonate type, sulfate type, and nonionic type emulsifiers. Specifically, alkali metal salt of disproportionated rosin acid, alkali metal salt of rosin acid, higher fatty acid alkali metal salt, alkyl sulfonate, alkyl aryl sulfonate, alkyl sulfate, alkyl aryl sulfate , A condensate of sodium naphthalenesulfonate and formaldehyde, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sorbitan fatty acid ester, polyoxyethylene acyl ester, etc., can be used alone or in combination of two or more . The optimum range of the amount of each emulsifying dispersant added varies depending on the type, but the range in which emulsion polymerization can be carried out stably is preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the initially charged monomer. 10 parts by weight is particularly preferred. The polymerization initiator is not particularly limited as long as it is a free radical generating substance, and examples thereof include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, paramentane hydroperoxide, and t-butyl hydroperoxide. Inorganic or organic peroxides such as oxide and cumene hydroperoxide, etc. are mentioned alone or with the above compounds and ferrous sulfate, hydrosulfite sodium, sodium formaldehyde sulfoxylate, thiosulfate, thiosulfite, organic A redox system in combination with a reducing substance such as amine is used.

  In the method of the present invention, a monomer mixture is added in the middle of polymerization using the space of a polymerization vessel formed by an increase in latex specific gravity as the polymerization proceeds. Therefore, the more monomer mixture introduced before the start of polymerization, the larger the space generated by polymerization, and the addition of a large amount of monomer mixture becomes possible. However, if there is already a space in the polymerization vessel at the start of polymerization, the efficiency is poor from the viewpoint of productivity, and thus the polymerization is started from a state in which the polymerization vessel is completely filled. In this respect, in the method in which the amount of the monomer mixture charged at the start of polymerization as in Patent Document 1 is small, there is little space generated as the polymerization proceeds, and the emulsifier aqueous solution is added together with the monomer mixture. The amount of the monomer mixture that can be added is small, and the productivity improvement is not sufficient.

  The polymerization conversion rate for stopping the polymerization in the method of the present invention is not particularly limited as long as the chloroprene rubber can be obtained, but the fluidity of the obtained chloroprene rubber is maintained while maintaining the productivity. In order to maintain processability, the content is preferably 60 to 85%, particularly preferably 62 to 75%, based on the sum of the monomers at the start of polymerization and the monomers added during the polymerization. Here, the polymerization terminator added when the polymerization is terminated is not particularly limited as long as it is a compound that traps radicals. For example, phenothiazine, 2,2′-methylenebis- (4-methyl-6- 6) t-butylphenol), 2,2'-methylenebis- (4-ethyl-6-t-butylphenol), 2,6-di-t-butyl-4-methylphenol, hydroquinone, 4-methoxyhydroquinone, N, N- Examples include radical inhibitors such as diethylhydroxylamine, and one or two or more of them are used.

  The polymerization temperature in the method of the present invention can be carried out in the range of 0 to 60 ° C, preferably in the range of 5 to 50 ° C.

  The chloroprene rubber obtained by the method for producing chloroprene rubber excellent in productivity of the present invention has the same quality as the chloroprene rubber obtained by the usual polymerization method. Therefore, in the same manner as the conventionally known chloroprene rubber, it is mixed with a vulcanizing agent, a vulcanization accelerator, a reinforcing agent, a filler, a plasticizer, an anti-aging agent, etc. by a kneading machine such as a roll, a kneader or a Banbury, Further, a vulcanized product having performance equivalent to that of chloroprene rubber obtained by an ordinary polymerization method can be obtained by vulcanizing after molding into a shape suitable for the purpose.

  The polymerization method of the present invention increases the production amount per batch because a monomer mixture is added during the polymerization, and avoids a rapid increase in heat of polymerization and an increase in latex viscosity. It is clear that the productivity of chloroprene rubber can be improved because the polymerization can be carried out at a polymerization rate of 5%. Further, the quality of the chloroprene rubber obtained is equivalent to that of the chloroprene rubber obtained by the conventional polymerization method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples.

  The Mooney viscosity of the chloroprene rubber in the examples was measured and evaluated according to JIS K6388 (1995 edition). The hardness of the vulcanizate characteristic was measured according to JIS K6253 (1997 edition). The rupture elongation, rupture strength, and 100% stress of the vulcanizate were evaluated using a dumbbell-shaped No. 3 type test piece according to JIS K6251 (1993 edition) at a pulling speed of 500 mm / min.

  In the following description, “part by weight” means a weight ratio in which 100 parts by weight of all monomers charged into the polymerization vessel before the start of polymerization is represented.

Reference example 1
The following is Reference Example 1 in which chloroprene rubber was produced by a conventional polymerization method.

  In accordance with the polymerization formulation shown in Table 1, 100 parts by weight of 2-chloro-1,3-butadiene and 0.200 parts by weight of n-dodecyl mercaptan were charged into a 10 L autoclave equipped with a stirrer, 3.5 parts by weight of potassium rosinate, naphthalene sulfone. An emulsion composed of 0.7 parts by weight of a sodium acid formaldehyde condensate, 0.25 parts by weight of sodium hydroxide and 90 parts by weight of distilled water was added thereto, and after sufficiently purging with nitrogen, the mixture 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 polymerization time was 240 minutes, and the production amount was calculated from 65% to 65 parts by weight with a conversion rate of 100 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.27 parts by weight / minute.

  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.

  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. The normal physical properties of the vulcanizate were measured. Table 1 shows the characteristic values of the vulcanizates.

参考例２
以下は、従来の重合方法によりクロロプレンゴムを製造した参考例２である。

Reference example 2
The following is Reference Example 2 in which chloroprene rubber was produced by a 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 polymerization time was 240 minutes, and the production amount was calculated from 65% to 65 parts by weight with a conversion rate of 100 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.27 parts by weight / minute.

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

  The obtained chloroprene rubber was evaluated in the same manner as in Reference Example 1. Table 1 shows the characteristic values of the vulcanizates.

Example 1
In accordance with the polymerization formulation shown in Table 3, 100 parts by weight of 2-chloro-1,3-butadiene and 0.211 parts by weight of n-dodecyl mercaptan were charged into a 10 L autoclave with a stirrer, and 3.5 parts by weight of potassium rosinate and naphthalene sulfone. An emulsion composed of 0.7 parts by weight of a sodium acid formaldehyde condensate, 0.25 parts by weight of sodium hydroxide and 90 parts by weight of distilled water was added thereto, and after sufficiently purging with nitrogen, the mixture 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.

  From the time when the polymerization conversion reached 40%, a mixture of 11 parts by weight of 2-chloro-1,3-butadiene and 0.022 parts by weight of n-dodecyl mercaptan was fed into the polymerization vessel at a rate of 0.11 part by weight / minute. Polymerization was continued while adding.

  When the addition of the monomer mixture is completed, the polymerization is continued, and when the conversion rate with respect to all the monomers becomes 65%, 0.02 part by weight of phenothiazine is dissolved in toluene to make a sodium dodecylbenzenesulfonate aqueous solution. The mixture was emulsified and a mixture of 0.05 part by weight of N, N-diethylhydroxylamine was added as a terminator to terminate the polymerization. The polymerization time was 240 minutes, and the production amount was calculated to be 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.30 parts by weight / minute, which is 11% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 1. It is clear that the productivity is very excellent in comparison.

  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.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  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. When the normal physical properties of the vulcanizate were measured, they had properties that were not different from the chloroprene rubber obtained in Reference Example 1. The characteristic values of the vulcanizate are shown in Table 3.

実施例２
表３に示す重合処方に従い、重合開始前の単量体混合物を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０．２３４重量部に、重合途中より添加する単量体混合物を２−クロロ−１，３−ブタジエン１０．２重量部、２，３−ジクロロ−１，３−ブタジエン０．８重量部、ｎ−ドデシルメルカプタン０．０２４重量部に変更した以外は実施例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。重合時間は２４０分、生産量は全単量体１１１重量部の転化率６５％から７２．２重量部と算出した。両者の商として時間当りの生産量は０．３０重量部／分と算出され、参考例２の時間当りの生産量０．２７重量部／分よりも１１％向上しており、参考例２と比較して生産性が非常に優れていることが明らかである。

Example 2
According to the polymerization prescription shown in Table 3, the monomer mixture before the start of polymerization was 93 parts by weight of 2-chloro-1,3-butadiene, 7 parts by weight of 2,3-dichloro-1,3-butadiene, n-dodecyl mercaptan 0 234 parts by weight of the monomer mixture added during the polymerization is 10.2 parts by weight of 2-chloro-1,3-butadiene, 0.8 part by weight of 2,3-dichloro-1,3-butadiene, n- Polymerization was carried out in the same manner as in Example 1 except that the amount was changed to 0.024 parts by weight of dodecyl mercaptan to obtain chloroprene rubber. The polymerization time was 240 minutes, and the production amount was calculated to be 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated as 0.30 parts by weight / minute, which is 11% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 2. It is clear that the productivity is very excellent in comparison.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. The characteristic values of the vulcanizate are shown in Table 3.

Example 3
In accordance with the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was 97 parts by weight of 2-chloro-1,3-butadiene, 3 parts by weight of 2,3-dichloro-1,3-butadiene, and n-dodecyl mercaptan. The monomer mixture added in the middle of the polymerization to 227 parts by weight is 10 parts by weight of 2-chloro-1,3-butadiene, 1 part by weight of 2,3-dichloro-1,3-butadiene, and n-dodecyl mercaptan. Polymerization was carried out in the same manner as in Example 1 except that the amount was changed to 024 parts by weight to obtain chloroprene rubber. The polymerization time was 240 minutes, and the production amount was calculated to be 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated as 0.30 parts by weight / minute, which is 11% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 2. It is clear that the productivity is very excellent in comparison.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. The characteristic values of the vulcanizate are shown in Table 3.

Example 4
According to the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was added to 100 parts by weight of 2-chloro-1,3-butadiene and 0.205 parts by weight of n-dodecyl mercaptan, and the conversion start of addition of the monomer mixture was started. The polymerization was carried out in the same manner as in Example 1 except that the addition rate was changed to 25% and the addition rate was changed to 0.07 parts by weight / minute, to obtain chloroprene rubber. The polymerization time was 240 minutes, and the production amount was calculated to be 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.30 parts by weight / minute, which is 11% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 1. It is clear that the productivity is very excellent in comparison.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. The characteristic values of the vulcanizate are shown in Table 3.

Example 5
According to the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was added to 100 parts by weight of 2-chloro-1,3-butadiene and 0.225 parts by weight of n-dodecyl mercaptan, and the conversion start of the addition of the monomer mixture was started. Was performed in the same manner as in Example 1 except that the addition rate was changed to 0.28 parts by weight / min and the polymerization temperature was changed to 45 ° C. to obtain a chloroprene rubber. The polymerization time was 230 minutes, and the production amount was calculated to be 72.2 parts by weight from a conversion rate of 65% of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.31 parts by weight / minute, which is 15% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 1. It is clear that the productivity is very excellent in comparison.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. The characteristic values of the vulcanizate are shown in Table 3.

Example 6
In accordance with the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was 97 parts by weight of 2-chloro-1,3-butadiene, 3 parts by weight of 2,3-dichloro-1,3-butadiene, and n-dodecyl mercaptan. The monomer mixture added to 224 parts by weight during the polymerization was changed to 6 parts by weight of 2-chloro-1,3-butadiene and 0.011 parts by weight of n-dodecyl mercaptan, and the addition rate of the monomer mixture was changed. Polymerization was carried out in the same manner as in Example 1 except that the amount was changed to 0.05 parts by weight / minute, to obtain a chloroprene rubber. The polymerization time was 240 minutes, and the production amount was calculated to be 68.9 parts by weight from 65% conversion of 106 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.29 parts by weight / minute, which is 7.4% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 2. It is clear that productivity is superior to 2.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. The characteristic values of the vulcanizate are shown in Table 3.

Example 7
In accordance with the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was 95 parts by weight of 2-chloro-1,3-butadiene, 5 parts by weight of 2,3-dichloro-1,3-butadiene, and n-dodecyl mercaptan. The monomer mixture added in the middle of the polymerization to 252 parts by weight is 10.4 parts by weight of 2-chloro-1,3-butadiene, 0.6 part by weight of 2,3-dichloro-1,3-butadiene, n- Polymerization was carried out in the same manner as in Example 1 except that the amount was changed to 0.024 parts by weight of dodecyl mercaptan, the conversion rate at the start of addition of the monomer mixture was changed to 50%, and the addition rate was changed to 0.73 parts by weight / minute. And chloroprene rubber was obtained. The polymerization time was calculated to be 245 minutes, and the production amount was 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.29 parts by weight / minute, which is 7.4% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 2. It is clear that productivity is superior to 2.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. The characteristic values of the vulcanizate are shown in Table 3.

Example 8
In accordance with the polymerization formulation shown in Table 3, the monomer mixture before the start of polymerization was 97 parts by weight of 2-chloro-1,3-butadiene, 3 parts by weight of 2,3-dichloro-1,3-butadiene, and n-dodecyl mercaptan. The monomer mixture added in the middle of the polymerization to 235 parts by weight was changed to 11 parts by weight of 2-chloro-1,3-butadiene and 0.023 parts by weight of n-dodecyl mercaptan. Polymerization was carried out in the same manner as in Example 1 except that the rate was changed to 50% and the addition rate was changed to 1.83 parts by weight / min to obtain chloroprene rubber. The polymerization time was calculated to be 245 minutes, and the production amount was 72.2 parts by weight from 65% conversion of 111 parts by weight of all monomers. As a quotient of both, the production amount per hour was calculated to be 0.29 parts by weight / minute, which is 7.4% higher than the production amount per hour of 0.27 parts by weight / minute in Reference Example 2. It is clear that productivity is superior to 2.

  Table 3 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. The characteristic values of the vulcanizate are shown in Table 3.

Comparative Example 1
In accordance with the polymerization formulation shown in Table 4, the monomer mixture before the start of polymerization is added to 100 parts by weight of 2-chloro-1,3-butadiene and 0.204 parts by weight of n-dodecyl mercaptan from the middle of the polymerization. Was changed to 1 part by weight of 2-chloro-1,3-butadiene and 0.002 part by weight of n-dodecyl mercaptan, the conversion of starting addition of the monomer mixture was 10%, and the addition rate was 0.06 parts by weight / minute. Polymerization was carried out in the same manner as in Example 1 except that the chloroprene rubber was obtained. Since the conversion at the start of addition of the monomer mixture was low, the space of the polymerization vessel expanding as the polymerization progressed was insufficient, and there were few monomers that could be added. The polymerization time was 240 minutes, and the production amount was calculated to be 65.7 parts by weight from 65% conversion of 101 parts by weight of all monomers. As the quotient of both, the production amount per hour is calculated to be 0.27 parts by weight / minute, which is equivalent to the production amount per hour in Reference Example 1, and that the productivity is inferior compared to the polymerization method of the present invention. it is obvious.

  Table 4 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. Table 4 shows the characteristic values of the vulcanizates.

比較例２
表４に示す重合処方に従い、重合開始前の単量体混合物を２−クロロ−１，３−ブタジエン１００重量部、ｎ−ドデシルメルカプタン０．２２１重量部に、重合途中より添加する単量体混合物を２−クロロ−１，３−ブタジエン１０重量部、２，３−ジクロロ−１，３−ブタジエン１重量部、ｎ−ドデシルメルカプタン０．０２３重量部に変更し、単量体混合物の添加開始転化率を６３％、添加速度を２．２０重量部／分に変更した以外は実施例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。単量体の添加開始転化率が高く、重合停止転化率に達するまでの時間が短いため、添加速度を非常に高く設定せざるを得なかった。それにより急激な単量体増加に伴い重合熱が著しく増加したため、重合器内ラテックスを設定温度に保つには一時的に重合速度を低減し、重合熱を抑制する必要があった。よって重合時間が２７５分と長くなった。生産量は全単量体１１１重量部の転化率６５％から７２．２重量部、両者の商として時間当りの生産量は０．２６重量部／分と算出され、本発明の重合方法に比べ生産性が劣っていることが明らかである。

Comparative Example 2
According to the polymerization prescription shown in Table 4, the monomer mixture before the start of polymerization is added to 100 parts by weight of 2-chloro-1,3-butadiene and 0.221 parts by weight of n-dodecyl mercaptan from the middle of the polymerization. Is changed to 10 parts by weight of 2-chloro-1,3-butadiene, 1 part by weight of 2,3-dichloro-1,3-butadiene, and 0.023 parts by weight of n-dodecyl mercaptan. Polymerization was carried out in the same manner as in Example 1 except that the rate was changed to 63% and the addition rate was changed to 2.20 parts by weight / min to obtain chloroprene rubber. Since the monomer addition start conversion rate was high and the time required to reach the polymerization termination conversion rate was short, the addition rate had to be set very high. As a result, the heat of polymerization markedly increased with a rapid increase in monomer, and therefore it was necessary to temporarily reduce the polymerization rate and suppress the heat of polymerization in order to keep the latex in the polymerization vessel at the set temperature. Therefore, the polymerization time was as long as 275 minutes. The production amount is calculated from 65% to 72.2 parts by weight of the conversion rate of 111 parts by weight of all monomers, and the quotient of both is calculated to be 0.26 parts by weight / minute, compared with the polymerization method of the present invention. It is clear that productivity is inferior.

  Table 4 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 2. Table 4 shows the characteristic values of the vulcanizates.

Comparative Example 3
According to the polymerization prescription shown in Table 4, the monomer mixture before the start of polymerization was 93 parts by weight of 2-chloro-1,3-butadiene, 7 parts by weight of 2,3-dichloro-1,3-butadiene, n-dodecyl mercaptan 0 The monomer mixture added in the middle of the polymerization to 234 parts by weight was 23.3 parts by weight of 2-chloro-1,3-butadiene, 1.7 parts by weight of 2,3-dichloro-1,3-butadiene, n- Polymerization was carried out in the same manner as in Example 1 except that the content was changed to 0.056 parts by weight of dodecyl mercaptan and the addition rate of the monomer mixture was changed to 0.25 parts by weight / min. Since an attempt was made to add more monomer than the space corresponding to the expanding polymerization vessel, the latex overflowed from the polymerization vessel, and it was impossible to add the total amount of the monomer, and the polymerization was stopped.

Comparative Example 4
In accordance with the polymerization formulation shown in Table 4, the monomer mixture before the start of polymerization is added to 100 parts by weight of 2-chloro-1,3-butadiene and 0.204 parts by weight of n-dodecyl mercaptan from the middle of the polymerization. Polymerization was carried out in the same manner as in Example 1 except that 1 part by weight of 2-chloro-1,3-butadiene and 0.001 part by weight of n-dodecyl mercaptan were changed to obtain chloroprene rubber. Since the polymerization time was 240 minutes and the amount of the monomer mixture added during the polymerization was small, the production amount was calculated as 65% to 65.7 parts by weight with a conversion rate of 101% by weight of all monomers. As the quotient of both, the production amount per hour is calculated to be 0.27 parts by weight / minute, which is equivalent to the production amount per hour in Reference Example 1, and that the productivity is inferior compared to the polymerization method of the present invention. it is obvious.

  Table 4 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. Table 4 shows the characteristic values of the vulcanizates.

Comparative Example 5
According to the polymerization formulation shown in Table 4, the monomer mixture before the start of polymerization was changed to 100 parts by weight of 2-chloro-1,3-butadiene and 0.216 parts by weight of n-dodecyl mercaptan, and added in the middle of the polymerization. Polymerization was carried out in the same manner as in Example 1 except that the addition rate of the body mixture was changed to 2.20 parts by weight / min to obtain chloroprene rubber. The monomer addition rate is very high, and the heat of polymerization significantly increases with rapid monomer increase. To keep the latex in the polymerization vessel at the set temperature, the polymerization rate is temporarily reduced to suppress the heat of polymerization. There was a need to do. Therefore, the polymerization time was as long as 280 minutes. The production amount is calculated from 65% to 72.2 parts by weight of the conversion rate of 111 parts by weight of all monomers, and the quotient of both is calculated to be 0.26 parts by weight / minute, compared with the polymerization method of the present invention. It is clear that productivity is inferior.

  Table 4 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. Table 4 shows the characteristic values of the vulcanizates.

Comparative Example 6
According to the polymerization prescription shown in Table 4, the monomer mixture before the start of polymerization was 93 parts by weight of 2-chloro-1,3-butadiene, 7 parts by weight of 2,3-dichloro-1,3-butadiene, n-dodecyl mercaptan 0 The monomer mixture added in the middle of the polymerization to 234 parts by weight was changed to 6 parts by weight of 2-chloro-1,3-butadiene and 0.003 parts by weight of n-dodecyl mercaptan. Polymerization was carried out in the same manner as in Example 1 except that the rate was changed to 25% and the addition rate was changed to 0.01 parts by weight / min. Even after reaching, a large amount of unadded monomer remained, so the polymerization was stopped.

Comparative Example 7
In this comparative example, there is little monomer charged into the polymerization vessel at the start of polymerization, and in the description of 100 parts by weight of the monomer charged at the start of polymerization as in the previous examples and comparative examples, it is added during the polymerization. The weight ratio of the other components including the monomer mixture increases, making it difficult to grasp the situation. Therefore, the weight ratio with the total amount of monomers added at the start of polymerization and during the polymerization as 100 parts by weight was described as parts by weight. In addition, in order to compare productivity with the examples of the present invention, the weight ratio in Example 1 with the amount of monomers charged at the start of polymerization being 100 parts by weight is also shown.

  According to the polymerization prescription shown in Table 5, the monomer mixture at the start of polymerization was 8.7 parts by weight of 2-chloro-1,3-butadiene (the monomer amount at the start of polymerization in Example 1 was 100 parts by weight). The weight ratio is 9.1 parts by weight, the same applies hereinafter), n-dodecyl mercaptan 0.020 part by weight (0.021 part by weight), and the emulsion is 0.52 part by weight potassium rosinate (0.55 part by weight). Part), 0.098 part by weight (0.10 part by weight) of formaldehyde condensate of sodium naphthalenesulfonate, 0.084 part by weight (0.09 part by weight) sodium hydroxide, 61 part by weight (64 parts by weight) distilled water The polymerization was started in the same manner as in Example 1. From the time when the conversion rate reached 15%, 91.3 parts by weight (95.9 parts by weight) of 2-chloro-1,3-butadiene and 0.235 parts by weight (0.247 parts by weight) of n-dodecyl mercaptan A monomer mixture consisting of 2.09 parts by weight (2.19 parts by weight) of potassium rosinate, 0.388 parts by weight (0.41 parts by weight) of a formaldehyde condensate of sodium naphthalenesulfonate, 0.445 parts by weight of sodium hydroxide The emulsion previously mixed and emulsified with an emulsion composed of parts by weight (0.47 parts by weight) and 19 parts by weight (20 parts by weight) of distilled water was 0.46 parts by weight per minute (0 Polymerization was continued while adding at a rate of .48 parts by weight), and the polymerization was stopped in the same manner as in Example 1. The total amount of monomers combined at the start of polymerization and during the addition was 105 parts by weight relative to the total amount of monomers charged at the start of polymerization in Example 1, and the emulsion was added together with the monomer mixture during the polymerization. The total amount of monomers in Example 1 could not be increased as much as 111 parts by weight. The production amount was calculated to be 68.3 parts by weight from a conversion rate of 65 parts by weight of 65%. In addition, since there are few monomers and emulsions to be charged in the initial stage of polymerization, the heat conduction performance of the polymerization vessel is lowered, and it is difficult to remove the polymerization heat of the monomer added during the polymerization. In order to keep the latex in the polymerization vessel at the set temperature, it was necessary to reduce the polymerization rate, and the polymerization time was 250 minutes. The production amount per hour, which is the quotient of the production amount and the polymerization time, is calculated to be 0.27 parts by weight / minute, and it is clear that the productivity is inferior to the polymerization method of the present invention.

  Table 5 shows the raw rubber Mooney viscosity of the obtained chloroprene rubber. Since a large amount of chain transfer agent was used, the value was smaller than in each example of the present invention, but it was in the category of chloroprene rubber, and it was determined that adjustment was possible by reducing the amount of chain transfer agent.

  When the obtained chloroprene rubber was evaluated in the same manner as in Example 1, it had physical properties that were not different from those of the chloroprene rubber obtained in Reference Example 1. Table 5 shows the characteristic values of the vulcanizates.

Claims (3)

In the emulsion polymerization of chloroprene rubber, when the polymerization conversion rate relative to the monomer mixture at the start of polymerization is 15 to 60%, a monomer mixture comprising 2-chloro-1,3-butadiene and a chain transfer agent, or 2 A monomer mixture comprising at least one comonomer copolymerizable with chloro-1,3-butadiene, 2-chloro-1,3-butadiene and a chain transfer agent, and during polymerization The monomer mixture to be added is 2 to 20 parts by weight with respect to 100 parts by weight of the monomer mixture at the start of polymerization, and is added at a rate of 0.02 to 2 parts by weight / minute. A method for producing chloroprene rubber. 2-chloro- in a monomer mixture comprising 2-chloro-1,3-butadiene, at least one comonomer copolymerizable with 2-chloro-1,3-butadiene and a chain transfer agent added during polymerization The ratio of 1,3-butadiene to at least one comonomer copolymerizable with 2-chloro-1,3-butadiene is 25/75 to 99/1 by weight. The manufacturing method of chloroprene rubber of description. The method for producing a chloroprene rubber according to claim 1 or 2, wherein the polymerization is stopped at a polymerization conversion ratio of 60 to 85% with respect to all monomers.