阅读说明：本技术 包含氯丁二烯单体单元和不饱和腈单体单元的统计共聚物的制造方法、统计共聚物、胶乳和其用途 (Process for producing statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, statistical copolymer, latex, and use thereof ) 是由 西野涉 大贯俊 藤本光佑 石垣雄平 萩原尚吾 山岸宇一郎 于 2018-05-11 设计创作，主要内容包括：提供：耐油性良好的、包含氯丁二烯单体单元和不饱和腈单体单元的统计共聚物。提供一种包含氯丁二烯单体单元和不饱和腈单体单元的统计共聚物的制造方法,其包括如下工序：聚合反应开始后另行连续添加或间歇添加10次以上的氯丁二烯单体。使用本发明的统计共聚物的橡胶组合物、包含该橡胶组合物的硫化成型体的耐油性、机械强度、低温压缩永久变形、和抗弯曲疲劳性优异。(Providing: a statistical copolymer having excellent oil resistance and comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit. Provided is a method for producing a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, comprising the steps of: after the polymerization reaction is started, the chloroprene monomer is added continuously or intermittently 10 times or more. The rubber composition using the statistical copolymer of the present invention, a vulcanized molded product comprising the rubber composition are excellent in oil resistance, mechanical strength, low-temperature compression set, and bending fatigue resistance.)

1. A method for producing a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, comprising the steps of: after the polymerization reaction is started, the chloroprene monomer is added continuously or intermittently 10 times or more.

2. The manufacturing method according to claim 1, comprising the steps of: the time when the polymerization reaction starts is set to t (0), n is an integer of 1 or more, the amount of chloroprene monomer added during the time dt (n +1) between the time t (n) and the time t (n +1) is determined based on the total amount of the polymerization conversion amount of chloroprene monomer and unsaturated nitrile monomer during the time dt (n) between the time t (n-1) and the time t (n) and the ratio of unreacted chloroprene monomer and unsaturated nitrile monomer is kept constant.

3. The production method according to claim 1, wherein the polymerization reaction comprises the following steps:

calculating a polymerization ratio of a chloroprene monomer and an unsaturated nitrile monomer based on a specific gravity of a latex containing the chloroprene monomer and the unsaturated nitrile monomer;

calculating the amount of unreacted chloroprene monomer and the amount of unreacted unsaturated nitrile monomer based on the polymerization ratio; and the combination of (a) and (b),

separately adding a predetermined amount of the chloroprene monomer separately to the latex at a time when a difference between an amount of the chloroprene monomer obtained by multiplying an amount of the unreacted unsaturated nitrile monomer by a monomer ratio at the start of polymerization and an amount of the unreacted chloroprene monomer separately added is equal to a separately added predetermined amount obtained by dividing a total amount of the chloroprene monomer previously added in the separately intermittent addition by the number of times of separately adding.

4. The production method according to any one of claims 1 to 3, wherein a xanthate compound is added as a chain transfer agent.

5. The production process according to any one of claims 1 to 4, wherein the polymerization temperature is maintained at 5 to 20 ℃.

6. A statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, which is obtained by the production method according to any one of claims 1 to 5.

7. A statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units made by: the production method is characterized in that the time when the polymerization reaction starts is set as t (0), n is an integer of 1 or more, the addition amount of the chloroprene monomer in the time dt (n +1) between the time t (n) and the time t (n +1) is determined based on the total amount of the polymerization conversion amount of the chloroprene monomer and the unsaturated nitrile monomer in the time dt (n) between the time t (n-1) and the time t (n), and the ratio of the unreacted chloroprene monomer and the unsaturated nitrile monomer is kept constant.

8. The statistical copolymer according to claim 6 or 7, wherein the polymerization temperature is maintained at 5 to 20 ℃.

9. A statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, wherein when a vulcanized rubber produced using the statistical copolymer under the following sample production conditions (I) is evaluated, the oil resistance to IRM903 oil measured in accordance with JIS K6258 is Δ W < + 15%, the compression set at 0 ℃ after 72 hours measured in accordance with JIS K6262 is 25% or less, and the bending fatigue resistance at 40 ℃ measured in accordance with JIS K6260 is 10 ten thousand or more,

sample preparation conditions (I):

a vulcanized rubber was produced by kneading 100 parts by mass of a statistical copolymer with 2 parts by mass of 4,4 '-bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine, 4 parts by mass of magnesium oxide, 50 parts by mass of carbon black, 5 parts by mass of a polyether ester plasticizer, 5 parts by mass of zinc oxide, 1.5 parts by mass of ethylthiourea and 1 part by mass of N-phenyl-N' - (1, 3-dimethylbutyl) -p-phenylenediamine for 20 minutes using an 8-inch roll having a cooling water temperature of 40 ℃ to obtain a rubber composition, and then subjecting the rubber composition to a heat treatment at 170 ℃ for 20 minutes using an electric hot press in accordance with JIS K6250 and then to a heat treatment at 170 ℃ for 2 hours in heated air.

10. The statistical copolymer according to claim 9, wherein when the vulcanized rubber produced under the sample production condition (I) is evaluated by the statistical copolymer, mechanical properties measured according to JIS K6251 are: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

11. A statistical copolymer according to any one of claims 6 to 10, for use in a transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber or a sponge article.

12. A latex comprising the statistical copolymer of any one of claims 6 to 10.

13. The latex of claim 12 for use in adhesives.

14. The latex of claim 12 for use in dipping articles.

15. A resorcinol-formaldehyde-latex (RFL) treated article using the latex of claim 14.

16. A rubber composition comprising the statistical copolymer of any one of claims 6-10.

17. A vulcanized molded body comprising the rubber composition of claim 16.

18. The vulcanization-molded article of claim 17, which is a power transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealing member, an adhesive, a boot, a rubber cloth, a rubber roller, a vibration-proof rubber, or a sponge article.

19. A vulcanized molded product which is a vulcanized molded product of a statistical copolymer comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit, wherein the unsaturated nitrile monomer unit is 8 to 20 mass%, and which has an oil resistance to IRM903 oil measured in accordance with JIS K6258 of Δ W < + 15%.

20. The vulcanized molded article according to claim 19, wherein the compression set at 0 ℃ after 72 hours as measured according to JIS K6262 is 25% or less.

21. The vulcanized molded body according to claim 19 or 20, wherein the bending fatigue resistance at 40 ℃ measured according to JIS K6260 is 10 ten thousand or more.

22. A transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber or a sponge article, which comprises the vulcanized molded article according to any one of claims 19 to 21.

23. A vulcanized molded body comprising: a statistical copolymer of a chloroprene monomer unit and an unsaturated nitrile monomer unit in an amount of 8 to 12 mass% based on the unsaturated nitrile monomer unit, and has an oil resistance Δ W < + 15% to IRM903 oil measured according to JIS K6258 and a compression set of 20% or less after 72 hours at 0 ℃.

24. A sealing member or a hose member, which comprises the vulcanized molded article according to claim 23.

25. The vulcanized molded body according to claim 19 or 23, which has mechanical properties measured according to JIS K6251 of: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

Technical Field

The present invention relates to a process for the manufacture of a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, to a statistical copolymer, to a latex and to the use thereof.

Background

A method of copolymerizing chloroprene and an unsaturated nitrile compound has been known in the past, and for example, bulk polymerization by ultraviolet irradiation is exemplified (see patent document 1). In this method, it is difficult to increase the copolymerization amount of acrylonitrile due to the difference in reactivity between chloroprene and acrylonitrile. To overcome this problem, the following methods are known: chloroprene was added in portions to maintain the acrylonitrile concentration in the monomer high (see patent document 2). In addition, a method for producing a chloroprene copolymer containing an unsaturated nitrile blended therein is also known for the purpose of improving oil resistance (see patent document 3). These copolymers are suitably used for a transmission belt, a conveyor belt, a hose, a wiper, a dipped product, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber, and a sponge product by vulcanization molding (see patent documents 4 and 5 and non-patent document 1).

Disclosure of Invention

Problems to be solved by the invention

The oil resistance of the chloroprene copolymer obtained by the method of patent document 3 may be insufficient.

Accordingly, a primary object of the present invention is to provide: a statistical copolymer comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit, which has excellent oil resistance and further has excellent various mechanical properties.

Means for solving the problems

That is, the present invention provides a method for producing a statistical copolymer comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit, comprising the steps of: after the polymerization reaction is started, the chloroprene monomer is added continuously or intermittently 10 times or more. By the present production method, the ratio of the unreacted chloroprene monomer to the unsaturated nitrile monomer in the polymerization liquid can be kept constant during polymerization.

The above manufacturing method may include the steps of: the time when the polymerization reaction starts is set to t (0), n is an integer of 1 or more, the amount of chloroprene monomer added during the time dt (n +1) between the time t (n) and the time t (n +1) is determined based on the total amount of the polymerization conversion amount of chloroprene monomer and unsaturated nitrile monomer during the time dt (n) between the time t (n-1) and the time t (n) and the ratio of unreacted chloroprene monomer and unsaturated nitrile monomer in the polymerization liquid is kept constant.

Here, keeping the ratio of the unreacted chloroprene monomer to the unsaturated nitrile monomer in the polymerization liquid constant during the polymerization means that the mass ratio of the unsaturated nitrile monomer to the total of the chloroprene monomer and the unsaturated nitrile monomer is preferably within ± 10%, more preferably within ± 5% of the target value. For example, in the polymerization, when the mass ratio of the unsaturated nitrile monomer to the total of the unreacted chloroprene monomer and the unsaturated nitrile monomer in the polymerization liquid is maintained at 0.50, the mass ratio is preferably maintained in the range of 0.40 to 0.60, more preferably in the range of 0.45 to 0.55.

In the above production method, for example, when the mass ratio of the unsaturated nitrile monomer to the total of the unreacted chloroprene monomer and the unsaturated nitrile monomer in the polymerization solution is maintained at 0.50, the polymerization reaction may be started and then the following steps may be included: calculating a polymerization ratio of a chloroprene monomer and an unsaturated nitrile monomer based on a specific gravity of a latex containing the chloroprene monomer and the unsaturated nitrile monomer; calculating the amount of unreacted chloroprene monomer and the amount of unreacted unsaturated nitrile monomer based on the polymerization ratio; and a step of separately adding a predetermined amount of the chloroprene monomer separately to the latex at a time when the difference between the amount of the unreacted chloroprene monomer and the amount of the unreacted unsaturated nitrile monomer becomes equal to a separately added amount obtained by dividing the total amount of the chloroprene monomer previously added in the separate intermittent addition by the number of times of separate addition.

In the above production method, a xanthate compound may be added as a chain transfer agent.

In the above production method, the polymerization temperature may be maintained at 5 to 20 ℃.

The present invention provides a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, which is produced as follows: after the polymerization reaction is started, the chloroprene monomer is added continuously or intermittently 10 times or more.

The present invention provides a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, which is produced as follows: the production method is characterized in that the time when the polymerization reaction starts is set as t (0), n is an integer of 1 or more, the addition amount of the chloroprene monomer in the time dt (n +1) between the time t (n) and the time t (n +1) is determined based on the total amount of the polymerization conversion amount of the chloroprene monomer and the unsaturated nitrile monomer in the time dt (n) between the time t (n-1) and the time t (n), and the ratio of the unreacted chloroprene monomer and the unsaturated nitrile monomer is kept constant.

The statistical copolymer of the present invention can be produced by maintaining the polymerization temperature at 5 to 20 ℃.

The statistical copolymers described above can be used in transmission belts, conveyor belts, hoses, wipers, dipped goods, sealing members, adhesives, protective covers, rubber cloths, rubber rollers, vibration-proof rubbers or sponge goods.

The present invention provides a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, characterized in that when a vulcanized rubber produced using the statistical copolymer under the following sample production conditions (I) is evaluated, the oil resistance to IRM903 oil measured in accordance with JIS K6258 is Δ W < 15%, the compression set at 0 ℃ for 72 hours measured in accordance with JIS K6262 is 25% or less, preferably 20% or less, and the bending fatigue resistance at 40 ℃ measured in accordance with JIS K6260 is 10 ten thousand or more.

(sample preparation Condition (I))

100 parts by mass of a statistical copolymer, 2 parts by mass of 4,4 '-bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine, 4 parts by mass of magnesium oxide, 50 parts by mass of carbon black, 5 parts by mass of a polyether ester plasticizer, 5 parts by mass of zinc oxide, 1.5 parts by mass of ethylthiourea, and 1 part by mass of N-phenyl-N' - (1, 3-dimethylbutyl) -p-phenylenediamine were kneaded for 20 minutes using an 8-inch roll having a cooling water temperature of 40 ℃ to obtain a rubber composition. The obtained rubber composition was subjected to heat treatment at 170 ℃ for 20 minutes by an electric hot press and then at 170 ℃ for 2 hours in heated air in accordance with JIS K6250 to prepare a vulcanized rubber.

In the case of evaluating the vulcanized rubber produced under the sample production condition (I), the statistical copolymer of the present invention may have the following mechanical properties measured according to JIS K6251: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

The statistical copolymers of the invention can be used in drive belts, conveyor belts, hoses, wipers, dipped goods, sealing parts, adhesives, protective covers, rubber cloths, rubber rollers, vibration-proof rubbers or sponge goods.

The present invention provides a latex comprising the statistical copolymer described above.

The latex can be used for adhesives, dipped articles, or resorcinol-formaldehyde-latex (RFL) treated articles.

The invention provides a rubber composition comprising the statistical copolymer.

The present invention provides a vulcanized molded article comprising the rubber composition.

The vulcanized molded product may be a transmission belt, a conveyor belt, a hose, a wiper, a dipped product, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber or a sponge product.

The present invention provides a vulcanized molded product which is a statistical copolymer comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit in an amount of 8 to 20% by mass, more preferably 8 to 17% by mass, and which has an oil resistance Δ W of < + 15% to IRM903 oil as measured according to JIS K6258.

In the vulcanized molded article of the present invention, the compression set after 72 hours at 0 ℃ as measured according to JIS K6262 may be 25% or less.

In the vulcanized molded article of the present invention, the bending fatigue resistance at 40 ℃ measured in accordance with JIS K6260 may be 10 ten thousand or more.

The vulcanized molded article of the present invention can be used for a transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber, or a sponge article.

The mechanical properties of the vulcanized molded article of the present invention measured according to JIS K6251 may be: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

In the present invention, there is provided a vulcanized molded body comprising: the unsaturated nitrile monomer unit is a statistical copolymer of 8-12 mass% of chloroprene monomer units and unsaturated nitrile monomer units, and has an oil resistance to IRM903 oil measured in accordance with JIS K6258 of Δ W < + 15%, and a compression set at 0 ℃ after 72 hours measured in accordance with JIS K6262 of 20% or less.

The vulcanized molded article of the present invention can be used for a sealing member or a hose member.

The mechanical properties of the vulcanized molded article of the present invention measured according to JIS K6251 may be: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

"statistical copolymer" in the present invention means a copolymer capable of describing a distribution of monomer chains by a Bernoulli statistical model or by a first or second order Markov statistical model, as described in J.C. Randall "POLYMER SEQUENCE DETERMINATION, Carbon-13NMR Method" Academic Press, New York, 1977, pages 71-78. In the case where the statistical copolymer including a chloroprene monomer unit and an unsaturated nitrile monomer unit of the present embodiment is composed of a 2-membered monomer, the reactivity ratios r1 and r2 when the chloroprene monomer is M1, r1 may be in the range of 0.3 to 3000, and r2 may be 10 in the following Mayo-Lewis formula (I)^-5A range of 3.0. From a further point of view, "statistical copolymers" in the context of the present invention mean the use of a plurality of monomers by free radical polymerizationAnd (d) synthesizing the resulting copolymer. The term "statistical copolymer" is a concept including substantially random copolymers.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a statistical copolymer comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit, which has excellent oil resistance and further has excellent various mechanical properties.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described. The embodiments described below are representative embodiments of the present invention, and the scope of the present invention is not to be construed narrowly.

<1. statistical copolymer production method >

The production method of the present embodiment includes, in the step of polymerizing the chloroprene monomer and the unsaturated nitrile monomer, a step of separately continuously or intermittently adding the chloroprene monomer 10 times or more after the start of the polymerization reaction. Thus, a statistical copolymer (hereinafter, also simply referred to as "statistical copolymer") containing a chloroprene monomer unit and an unsaturated nitrile monomer unit can be produced. Here, "after the polymerization reaction is started" means after the polymerization initiator is added.

The polymerization method is not particularly limited, and radical polymerization is preferred. Examples of the radical polymerization include solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization, and among them, emulsion polymerization is preferable.

The reaction rate of the chloroprene monomer is faster than that of the unsaturated nitrile monomer. Therefore, the chloroprene monomer is consumed more rapidly than the unsaturated nitrile monomer in the polymerization system. When the ratio of the chloroprene monomer to the unsaturated nitrile monomer varies, the oil resistance of the resulting statistical copolymer may decrease. In the production method of the present embodiment, the chloroprene monomer and the unsaturated nitrile monomer can be kept at a constant ratio in the polymerization system by adding the main chloroprene monomer, which decreases due to the polymerization reaction, separately by continuously or intermittently adding the monomer 10 times or more. This makes it possible to obtain a statistical copolymer having improved oil resistance compared to conventional ones. The statistical copolymer produced by the production method of the present embodiment is also excellent in mechanical strength as shown in examples described below.

In the production method of the present embodiment, the chloroprene monomer is preferably added continuously or intermittently so that the ratio of the unreacted chloroprene monomer to the unsaturated nitrile monomer in the polymerization system becomes constant. From the viewpoint of improving the properties of the rubber containing the statistical copolymer, the ratio of the unreacted chloroprene monomer to the unsaturated nitrile monomer (unreacted chloroprene monomer/unreacted unsaturated nitrile monomer) in the polymerization system is preferably 10/90 to 90/10 in terms of mass ratio.

In the production method of the present embodiment, a part of the chloroprene monomer may be added to the polymerization system before the start of the polymerization reaction, and the remaining chloroprene monomer may be added separately or intermittently 10 times or more after the start of the polymerization reaction. The ratio of the total of the chloroprene monomer and the unsaturated nitrile monomer before the start of the polymerization reaction to water ((chloroprene monomer + unsaturated nitrile monomer)/water) is preferably 100/50 to 100/1000 in terms of mass ratio from the viewpoint of improving productivity.

Specific examples of the method of separately continuously or intermittently adding 10 or more times the chloroprene monomer will be described below. First, an example of a method of continuously adding a chloroprene monomer will be described.

In the case of continuous addition, the production method of the present embodiment preferably includes the steps of: the time when the polymerization reaction starts is set to t (0), n is an integer of 1 or more, the amount of chloroprene monomer added during the time dt (n +1) between the time t (n) and the time t (n +1) is determined based on the total amount of the polymerization conversion amount of chloroprene monomer and unsaturated nitrile monomer during the time dt (n) between the time t (n-1) and the time t (n) and the ratio of unreacted chloroprene monomer and unsaturated nitrile monomer is kept constant.

In the above-mentioned production method, in order to keep the ratio of the unreacted chloroprene monomer to the unsaturated nitrile monomer constant, the amount of the unsaturated nitrile monomer may be smaller than that of the chloroprene monomer added during the time dt (n +1) between the time t (n) and the time t (n + 1). In the case where a smaller amount of the unsaturated nitrile monomer relative to the chloroprene monomer to be added is contained, the mass ratio thereof (unsaturated nitrile monomer/chloroprene monomer) is as follows: the mass ratio of (unsaturated nitrile monomer component/chloroprene monomer component) in the statistical copolymer polymerized under the present production conditions is set as the upper limit. For example, if the mass ratio of (unsaturated nitrile monomer component/chloroprene monomer component) in the statistical copolymer polymerized under the present production conditions is 0.1, the mass ratio of (unsaturated nitrile monomer/chloroprene monomer) added is 0.1 as the upper limit. However, if the cost such as recovery of the residual monomer is taken into consideration, it is preferable to economically use only the chloroprene monomer.

The time t (n) and the time dt (n) may be arbitrarily set, and dt (n) is preferably 3000 seconds or less in order to facilitate continuous addition.

The method for calculating the total amount of the polymerization conversion amounts of the chloroprene monomer and the unsaturated nitrile monomer in the time dt (n) is not particularly limited. For example, the total amount of the respective polymerization conversion amounts of the chloroprene monomer and the unsaturated nitrile monomer can be determined by gas chromatography based on the amount of the chloroprene monomer and the amount of the unsaturated nitrile monomer at time t (n-1), the amount of the chloroprene monomer and the amount of the unsaturated nitrile monomer at time t (n), and the amount of the chloroprene monomer added at time dt (n). Further, the total amount of the respective polymerization conversion amounts of the chloroprene monomer and the unsaturated nitrile monomer can be determined by considering the specific gravities of the chloroprene monomer and the unsaturated nitrile monomer from the specific gravity of the polymerization liquid.

The step of determining the amount of the chloroprene monomer to be added in the time dt (n +1) based on the total amount of the above-mentioned amount of polymerization conversion is not particularly limited. For example, the ratio of the sum of the amount of chloroprene monomer at time t (n) and the amount of chloroprene monomer added at time dt (n +1) to the amount of unsaturated nitrile monomer at time t (n) may be calculated so as to match the ratio of the amount of chloroprene monomer to the amount of unsaturated nitrile monomer at time t (0).

Next, another example of a method of continuously adding a chloroprene monomer will be described by taking a case of using an acrylonitrile monomer as an unsaturated nitrile monomer as an example.

The manufacturing method of the present embodiment is as follows: the time when the polymerization reaction starts is set to t (0), n is set to an integer of 1 or more, and the change in heat quantity Q of the refrigerant is based on the time dt (n) between the time t (n-1) and the time t (n)_(n)The amount of chloroprene monomer added during the time dt (n +1) between the times t (n) and t (n +1) is determined. The above-mentioned refrigerant is used to cool the reaction vessel for the purpose of removing the heat of reaction.

First, the polymerization exotherm q during the period dt (n)_CP+AN(n)[kcal]Change in heat quantity with separately added chloroprene monomer Q_{Additional CP (n)}[kcal]Total heat quantity Qp defined by the sum of_(n)Heat variation with refrigerant Q_(n)The cumulative value of (B) is proportional to the total value of (C), and can be represented by the following general formula (II). In addition, "CP" means chloroprene and "AN" means acrylonitrile.

Qp_(n)＝σ×Q_(n)···(II)

Here, σ takes a different value depending on the polymerization recipe and the production conditions, and can be determined by performing the following experiment, for example.

(Experimental method)

In the polymerization in which all chloroprene monomers are initially charged at once, the change in heat quantity Q of the refrigerant at an arbitrary polymerization rate of at least 3 points is plotted_(n)Integral value of (a), (b), (c), (d) dt) and integral value of polymerization exotherm { (q { (n) } { (q }_cp(n) dt, σ can be obtained from the slope of the approximate line by the least square method.

Run at 16.0[ kg ]]In the case of polymerization of the chloroprene monomer (b), the heat quantity of the refrigerant changes Q at a polymerization rate of 35%_(n)1362[ kcal ]]When it is used, the total heat quantity is 1024 kcal]At a polymerization rate of 50%, the heat quantity of the refrigerant changes Q_(n)1922[ kcal ]]When it is used, the total heat quantity is 1463 kcal]At a polymerization rate of 65%, the heat quantity of the refrigerant changes Q_(n)2511[ kcal ]]When it is used, the total heat quantity is 1902 kcal]σ is 1.32 in terms of the slope of their approximate lines.

The heat quantity Q of chloroprene monomer added separately at time dt (n) changes with temperature_{Additional addition of cp (n)}[kcal]The following is obtained: specific heat (. gamma.) of chloroprene monomer is used_cp)0.385[kcal/(kg·K)]The amount W of chloroprene monomer added separately_{Additional addition of cp (n)}[kg]Measured value T of the internal temperature of the polymerization tank_in(n)[K]And an actual measurement value T of the temperature of a separately added chloroprene monomer_{Additional addition of cp (n)}[K]The molecular weight distribution was determined from the following general formula (III).

Q_{Additional CP (n)}＝γ_cp·W_{Additional addition of cp (n)}·(T_{Additional addition of cp (n)}-T_in(n))···(III)

Polymerization exotherm q in time dt (n)_(CP+AN)(n)According to the amount of chloroprene monomer polymerized during the time dt (n) (. DELTA.)_CP(n)[kg]Thermal polymerization of chloroprene monomer_cpThe amount of acrylonitrile monomer polymerized during the time dt (n) (. DELTA.)_AN(n)[kg]Heat of polymerization with acrylonitrile monomer_ANThe compound is represented by the following general formula (IV).

R is_cpAnd Γ_ANThe method is not particularly limited, and a value in known data may be used or may be experimentally obtained. Here, Γ_cpCitation 183[ kcal/kg]Gamma (Acta chem. stand., 4, 126(1950)) is used_ANCitation 343[ kcal/kg](J.Polym, Sci., 56, 313(1962)) was used.

q_(CP+AN)(n)＝183·Δ_CP(n)+343·Δ_AN(n)···(IV)

The acrylonitrile bonding rate α [ wt% ] in the statistical copolymer produced over time dt (n) was determined from the ratio of chloroprene monomer to acrylonitrile monomer at the start of polymerization and the reactivity ratios r1 to 14.75 and r2 to 0.014 when the chloroprene monomer was M1 defined by the following Mayo-Lewis formula (I))]. In the production method of the present embodiment, the amount W of chloroprene monomer added during the time dt (n +1) is controlled_{Additional CP (n)}Thus, α in the polymerization can be made constant.

Of chloroprene monomers added at times dt (n)Quantity W_{Additional CP (n)}Amount of polymerized chloroprene monomer_CP(n)Acrylonitrile monomer amount delta_AN(n)The amount R of the chloroprene monomer in the polymerization system in dt (n +1) of the reaction_CP(n+1)And the amount of acrylonitrile monomer R_AN(n+1)The following general formulae (V) and (VI) are established.

R_CP(n+1)＝R_CP(n)-Δ_CP(n)+W_{Additional CP (n)}···(V)

R_AN(n+1)＝R_AN(n)-Δ_AN(n)···(VI)

Here, if it is R_CP(0)/R_AN(0)＝R_CP(1)/R_AN(1)＝···＝R_CP(n)/R_AN(n)＝R_CP(n+1)/R_AN(n+1)Thus, the amount W of the chloroprene monomer added for the time dt (n +1) was determined based on the following general formula (VII)_{CP (n +1) is additionally added}。

R_CP(0)/R_AN(0)＝{R_CP(n)-Δ_CP(n)+W_{CP (n +1) is additionally added}}/{R_AN(n)-Δ_AN(n)}···(VII)

That is, the following general formula (VIII) holds.

W_{CP (n +1) is additionally added}＝R_CP(0)/R_AN(0)·(R_AN(n)-Δ_AN(n))-(R_CP(n)-Δ_CP(n))···(VIII)

Here, the amount of the chloroprene monomer polymerized in the time dt (n) (. DELTA.)_CP(n)And the amount of acrylonitrile monomer Delta_AN(n)The heat quantity Q (n) of the chloroprene monomer added separately in the period dt (n) and the heat quantity Q (n) of the refrigerant can be measured_{Additional CP (n)}The values were obtained by the following general formulae (IX) and (X), respectively.

Δ_CP(n)＝(100/α-1)·(σ·Q_(n)-Q_{Additional CP (n)})/{343+183·(100/α-1)}···(IX)

Δ_AN(n)＝(σ·Q_(n)-Q_{Additional CP (n)})/{343+183·(100/α-1)}···(X)

Substituted with the above general formula (IX) anddelta obtained by (X)_AN(n)And Δ_CP(n)Calculating W_{CP (n +1) is additionally added}The opening degree of the electromagnetic valve is adjusted so that the flow rate of the chloroprene monomer at the time of continuous addition becomes W_{CP (n +1) is additionally added}/dt。

Next, an example of a method of intermittently adding the chloroprene monomer 10 times or more will be described.

When the separate batch addition is performed, the same method as the above-mentioned separate continuous addition can be used. Specifically, the chloroprene monomer can be added intermittently by completing the addition of the chloroprene monomer at the time dt (n +1) before the time dt (n +1) elapses, with the time dt (n) set to be long and the rate of addition of the chloroprene monomer set to be fast. The addition of the chloroprene monomer may be repeated 10 or more times.

The time dt (n) is preferably 0.1 to 3000 seconds. The addition rate of the chloroprene monomer is preferably 2 parts by mass/min or less based on 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile monomer.

Next, another example of the method of separately adding intermittently will be described.

When the separate intermittent addition is performed, for example, when the mass ratio of the unsaturated nitrile monomer to the total of the unreacted chloroprene monomer and the unsaturated nitrile monomer in the polymerization liquid is maintained at 0.50, the production method of the present embodiment preferably includes the following steps after the start of the polymerization reaction: a step (1) for calculating the polymerization rate of a chloroprene monomer and an unsaturated nitrile monomer based on the specific gravity of a latex containing the chloroprene monomer and the unsaturated nitrile monomer; a step (2) of calculating the amount of unreacted chloroprene monomer and the amount of unreacted unsaturated nitrile monomer based on the polymerization rate; and (3) separately adding a predetermined amount of the separately added chloroprene monomer to the latex at a time when the difference between the amount of the unreacted chloroprene monomer and the amount of the unreacted unsaturated nitrile monomer becomes equal to a predetermined separate addition amount obtained by dividing the total amount of the chloroprene monomer to be added in the separate intermittent addition by the number of times of separate addition.

In this method, in the step (1), in order to calculate the polymerization rate, it is preferable to include the steps of: the correlation between the specific gravity of the latex and the polymerization rate of the chloroprene monomer and the unsaturated nitrile monomer was determined by preliminary experiments.

The preliminary test is performed by, for example, the following procedure. In the following examples, the case of using an acrylonitrile monomer as an unsaturated nitrile monomer is exemplified.

The monomer ratio of acrylonitrile monomer/chloroprene monomer is defined as a/b, the number of separate additions is defined as n, the amount of chloroprene monomer added separately per 1 time when the total amount of acrylonitrile monomer and chloroprene monomer is 100 parts by mass is defined as m parts by mass, and the amount of residual acrylonitrile monomer at specific gravity r is defined as C_rANMass part, residual chloroprene monomer amount is C_rCPAnd (4) parts by mass. Polymerizing the initially charged monomers, confirming r and C_rAN、C_rCPThe specific gravity R to be added is determined as the specific gravity R of the following general formula (XI)_b1. Then, similarly, the initially charged monomers are polymerized until the specific gravity R is reached_b1Then, m parts by mass of a chloroprene monomer was added to confirm that r and C were_rAN、C_rCPThe specific gravity R to be added is determined as the specific gravity R of the following general formula (XI)_b2. The same operation was performed n times to determine the additional specific gravity until the polymerization was completed.

In the production method of the present embodiment, when 10 or more separate intermittent additions are made, the amount of chloroprene monomer added after the start of the polymerization reaction is preferably 10 parts by mass or less per 1 addition per 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile monomer. When the addition is carried out intermittently, the addition rate is preferably 2 parts by mass/minute or less. By setting the amount to such a range, a statistical copolymer excellent in oil resistance and mechanical strength can be obtained.

In the production method of the present embodiment, the chloroprene monomer or the unsaturated nitrile monomer to be used may contain 1 or 2 or more kinds of other monomers. The monomer that can be used in the present embodiment is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include: 2, 3-dichloro-1, 3-butadiene, 1-chloro-1, 3-butadiene, sulfur, methyl methacrylate and salts thereof, ethyl methacrylate and salts thereof, propyl methacrylate and salts (all isomers) thereof, butyl methacrylate and salts (all isomers) thereof, 2-ethylhexyl methacrylate and salts thereof, isobornyl methacrylate and salts thereof, methacrylic acid and salts thereof, benzyl methacrylate and salts thereof, phenyl methacrylate and salts thereof, ethyl acrylate and salts thereof, propyl acrylate and salts (all isomers) thereof, butyl acrylate and salts (all isomers) thereof, 2-ethylhexyl acrylate and salts thereof, isobornyl acrylate and salts thereof, acrylic acid and salts thereof, benzyl acrylate and salts thereof, phenyl acrylate and salts thereof, styrene, and glycidyl methacrylate and salts thereof, and mixtures thereof, 2-hydroxyethyl methacrylate and salts thereof, hydroxypropyl methacrylate and salts thereof (all isomers), hydroxybutyl methacrylate and salts thereof (all isomers), N-dimethylaminoethyl methacrylate and salts thereof, N-diethylaminoethyl methacrylate and salts thereof, triethylene glycol methacrylic acid and salts thereof, itaconic anhydride and salts thereof, itaconic acid and salts thereof, glycidyl acrylate and salts thereof, 2-hydroxyethyl acrylate and salts thereof, hydroxypropyl acrylate and salts thereof (all isomers), hydroxybutyl acrylate and salts thereof (all isomers), N-dimethylaminoethyl acrylate and salts thereof, N-diethylaminoethyl acrylate and salts thereof, triethylene glycol acrylic acid and salts thereof, methacrylamide, N-methylacrylamide, N-methyla, N, N-dimethylacrylamide, N-butylmethacrylamide (all isomers), N-hydroxymethylmethacrylamide, N-hydroxyethylmethacrylamide, N-butylacrylamide (all isomers), N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, vinylbenzoic acid and salts thereof (all isomers), diethylaminostyrene (all isomers), alpha-ethylvinylbenzoic acid (all isomers), diethylaminoalpha-methylstyrene (all isomers), p-vinylbenzenesulfonic acid and salts thereof, p-vinylbenzenesulfonic acid sodium salt, trimethoxysilylpropyl methacrylate and salts thereof, triethoxysilylpropyl methacrylate and salts thereof, tributoxysilylpropyl methacrylate and salts thereof, and mixtures thereof, Dimethoxymethylsilylpropyl methacrylate and salts thereof, diethoxymethylsilylpropyl methacrylate and salts thereof, dibutoxymethylsilylpropyl methacrylate and salts thereof, diisopropoxymethylsilylpropyl methacrylate and salts thereof, dimethoxyethylsilylpropyl methacrylate and salts thereof, diethoxyethyldisilylpropyl methacrylate and salts thereof, dibutoxyethylsilylpropyl methacrylate and salts thereof, diisopropoxyethylsilylpropyl methacrylate and salts thereof, trimethoxysilylpropyl acrylate and salts thereof, triethoxysilylpropyl acrylate and salts thereof, tributoxysilylpropyl acrylate and salts thereof, dimethoxymethylsilylpropyl acrylate and salts thereof, diethoxymethylsilylpropyl acrylate and salts thereof, and mixtures thereof, Dibutoxymethylsilylpropyl acrylate and salts thereof, diisopropoxymethylsilylpropyl acrylate and salts thereof, dimethoxysilylpropyl acrylate and salts thereof, diethoxysilylpropyl acrylate and salts thereof, dibutoxysilylpropyl acrylate and salts thereof, diisopropoxysilylsilylpropyl acrylate and salts thereof, vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl chloride, vinyl fluoride, vinyl bromide, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, N-vinylpyrrolidone, N-vinylcarbazole, butadiene, isoprene, ethylene, propylene, and the like. In the above case, the content of the monomer in the chloroprene monomer or the unsaturated nitrile monomer is not particularly limited as long as the effect of the present invention is not impaired, and may be 20 parts by mass or less in total.

Examples of the unsaturated nitrile monomer used in the production method of the present embodiment include acrylonitrile, methacrylonitrile, acetonitrile, and phenylacetonitrile, and 1 kind thereof may be used alone or 2 or more kinds thereof may be used in combination. Among them, acrylonitrile is preferred from the viewpoint of ease of production and oil resistance.

The emulsifying/dispersing agent used in the emulsion polymerization is not particularly limited, and various anionic, nonionic, cationic and the like substances used in the emulsion polymerization of general chloroprene can be used. From the viewpoint of stability of the latex obtained, anionic emulsifiers are preferred, and examples thereof include rosin acid salts, alkyl sulfonates having 8 to 20 carbon atoms, alkylaryl sulfates, condensates of sodium naphthalenesulfonate and formaldehyde, and sodium alkyldiphenyloxide disulfonates. Among anionic emulsifiers, alkali metal salts of abietic acid are particularly preferably used because a statistical copolymer in the form of a film obtained by freeze-drying after completion of polymerization has an appropriate strength and can be prevented from excessive shrinkage and breakage. Rosin acids are mixtures of resin acids, fatty acids, and the like. The resin acids include abietic acid, neoabietic acid, palustric acid, palmitic acid, isopalmitic acid, dehydroabietic acid, dihydropalmitic acid, dihydroisopalmitic acid, dehydroabietic acid, dihydroabietic acid, etc., and the fatty acids include oleic acid, linoleic acid, etc. The composition of these components varies depending on the method of collecting rosin classified into gum rosin, wood rosin and oil rosin, the origin and species of pine, distillation purification and disproportionation (asymmetric) reaction, and is not limited in the present invention. In view of emulsion stability and ease of handling, it is preferable to use a sodium salt or a potassium salt. The concentration of the emulsifying/dispersing agent is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass. When the amount is 0.1% by mass or more, the monomers can be sufficiently emulsified, and when the amount is 10% by mass or less, the statistical copolymer is more likely to precipitate when it becomes a solid.

The polymerization initiator used in the emulsion polymerization is not particularly limited, and examples thereof include: potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctanoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutyrate, t-amyl peroxypivalate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium peroxydisulfate, ammonium peroxydisulfate, di-t-butyl nitrite, and dicumyl nitrite, organic peroxides such as 2, 2-azobis (isobutyronitrile), 2 ' -azobis (2-cyano-2-butane), 2 ' -azobisdimethylisobutyrate, 4 ' -azobis (4-cyanopentanoic acid), 1,1 ' -azobis (cyclohexanecarbonitrile), 2- (tert-butylazo) -2-cyanopropane, 2 ' -azobis [ 2-methyl-N- (1,1) -bis (hydroxymethyl) -2-hydroxyethyl ] propionamide, 2 ' -azobis [ 2-methyl-N-hydroxyethyl) ] -propionamide, 2 ' -azobis (N, N ' -dimethyleneisobutylamidine) dihydrochloride, 2 ' -azobis (2-amidinopropane) dihydrochloride, 2 ' -azobis (N, N ' -dimethyleneisobutylamine), 2 ' -azobis (2-methyl-N- [1, 1-bis (hydroxymethyl) -2-hydroxyethyl ] propionamide), Azo initiators such as 2,2 '-azobis (2-methyl-N- [1, 1-bis (hydroxymethyl) ethyl ] propionamide, 2' -azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ], 2-azobis (isobutylamide) dihydrate), 2 '-azobis (2,2, 4-trimethylpentane), and 2, 2' -azobis (2-methylpropane).

In the emulsion polymerization, a polymerization co-catalyst may be used. The polymerization co-catalyst to be used in the present embodiment is not particularly limited as long as the effects of the present invention are not impaired, and 1 or 2 or more kinds of known polymerization co-catalysts can be freely used. Examples thereof include L-ascorbic acid, tartaric acid, sodium bisulfite, zinc formaldehyde sulfoxylate or sodium formaldehyde sulfoxylate, methylenediamine sulfinic acid, glucose, formalin, anthraquinone β -sodium sulfonate, ferrous sulfate, copper sulfate, sodium bisulfite, thiourea and the like.

In the production method of the present embodiment, a chain transfer agent may be used to control the molecular weight. Without particular limitation, the following may be used: xanthate compounds such as N-dodecylmercaptan, t-dodecylmercaptan, N-octylmercaptan and the like, diisopropyl xanthogen disulfide, diethyl xanthogen disulfide and the like, iodoformaldehyde, benzyl 1-pyrroledithiocarbamate (alternatively referred to as benzyl 1-pyrroledithiocarbamate), benzylphenyldithiocarbamate, 1-benzyl-N, N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazole dithiocarbamate (alternatively referred to as benzyl 1-phenylethylimidazole dithiocarbamate), benzyl 1- (2-pyrrolidone) dithiocarbamate (alternatively referred to as benzyl 1- (2-pyrrolidone) dithiocarbamate), benzyl phthalimidyldithiocarbamate (alternatively referred to as benzyl phthalimidyldithiocarbamate) 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate (also known as 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate), 2-cyanobut-2-yl-1-pyrrole dithiocarbamate (also known as 2-cyanobut-2-yl-1-pyrrole dithiocarbamate), benzyl 1-imidazole dithiocarbamate (also known as benzyl 1-imidazole dithiocarbamate), 2-cyanoprop-2-yl-N, N-dimethyldithiocarbamate, benzyl N, N-diethyldithiocarbamate, cyanomethyl-1- (2-pyrrolidone) dithiocarbamate, 2- (ethoxycarbonylbenzyl) propan-2-yl-N, n-diethyldithiocarbamate, 1-phenylethyldithiobenzoate, 2-phenylpropan-2-yldithiocarbamate, 1-acetoxy-1-yl-ethyldithiobenzoate, 1- (4-methoxyphenyl) ethyldithiobenzoate, benzyldithioacetate, ethoxycarbonylmethyldithioacetate, 2- (ethoxycarbonyl) propan-2-yldithiocarbamate, 2-cyanoprop-2-yldithiocarbamate, tert-butyldithiobenzoate, 2,4, 4-trimethylpent-2-yldithiocarbamate, 2- (4-chlorophenyl) -propan-2-yldithiocarbamate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphinyldithiocarbamate, tert-butyltrithioperoxybenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, 1-methyl-1-phenyl-ethyl naphthalene-1-carboxylate, 4-cyano-4-methyl-4-thiobenzylsulfanylbutanoic acid, dibenzyl tetrathioterephthalate, carboxymethyldithiobenzoate, poly (ethylene oxide) having a dithiobenzoate end group, poly (ethylene oxide) having a 4-cyano-4-methyl-4-thiobenzylsulfanylbutanoic acid end group, 2- [ (2-phenylethylthio) sulfanyl ] propanoic acid, and mixtures thereof, 2- [ (2-Phenylethylthio) sulfanyl ] succinic acid, potassium 3, 5-dimethyl-1H-pyrazole-1-dithiocarbamate, cyanomethyl- (phenyl) dithiocarbamate, benzyl 4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano-1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, sodium, potassium, sodium, potassium, 2-chloro-2-butenyldithiocarbonate, benzyldithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobut-2-yl-4-chloro-3, 5-dimethyl-1H-pyrazole-1-dithioformate, cyanomethyl (phenyl) aminodithioformate, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2- [ [ (butylthio) thiomethyl ] thio ] propanoic acid, 2- [ [ (dodecylthio) thiomethyl ] thio ] propanoic acid, 2- [ [ (butylthio) thiomethyl ] thio ] succinic acid, benzyldithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanomethyl (phenyl) aminodithioformate, 2-cyano-2-propyltrithiocarbonate, dibenzyltrithiocarbonate, 2- [ [ (dodecylthio) thiomethyl ] thio ] succinic acid, 2- [ [ (dodecylthio) thiomethyl ] thio ] -2-methylpropionic acid, 2' - [ methylthiobis (thio) ] bis [ 2-methylpropionic acid ], 2-amino-1-methyl-2-oxoethylbutyl trithiocarbonate, benzyl-2- [ (2-hydroxyethyl) amino ] -1-methyl-2-oxoethyl trithiocarbonate, and thiocarbonyl compounds such as 3- [ [ [ (tert-butyl) thio ] thiomethyl ] thio ] propionic acid, cyanomethyldodecyltrithiocararbonate, diethylaminobenzyl trithiocarbonate and dibutylaminobenzyltrithiocarbonate. Among them, a xanthate compound is particularly preferably added. In the method for producing a chloroprene-acrylonitrile copolymer described in patent document 2, a thiol compound is used as a chain transfer agent, and a thiol-ene reaction generates a viscous by-product, and therefore, an operation of removing the by-product is required. However, by adding a xanthate compound as a chain transfer agent, the generation of by-products is suppressed, and therefore, the removal work of the by-products is not required, and the production efficiency of the statistical copolymer can be improved.

Further, the xanthogen-based compound has higher reactivity than other chain transfer agents, and therefore, a statistical copolymer having a high crosslinking density at the time of vulcanization can be obtained. It is believed that the high crosslink density contributes to the improvement in oil resistance of the statistical copolymer.

Examples of the xanthate-based compound include dialkyl xanthogen disulfides such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide, and dibutyl xanthogen disulfide. Further, there may be mentioned dialkyl xanthogenates trisulfide such as diethyl xanthogenate trisulfide, diisopropyl xanthogenate trisulfide and dibutyl xanthogenate trisulfide. Further, dialkyl xanthogen esters having 4 or more atoms or more of the sulfur atom to which the xanthogen group is bonded, such as dialkyl xanthogen polysulphide esters, for example, diethyl xanthogen polysulphide, diisopropyl xanthogen polysulphide, dibutyl xanthogen polysulphide, and the like, can also be used. The number of carbon atoms in the alkyl group of the sulfurized dialkyl xanthate compound is preferably 1 to 10, more preferably 1 to 6, in terms of solubility in chlorobutadiene monomer.

The amount of the chain transfer agent to be added is not particularly limited, but is preferably 0.002 to 20 parts by mass based on 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile monomer. By setting the range as above, the control of the polymerization reaction can be easily performed.

The polymerization temperature in the emulsion polymerization is not particularly limited, but is preferably 0 to 59 ℃ and particularly preferably 5 to 55 ℃. By setting the polymerization temperature to 5 ℃ or higher, the emulsion can be prevented from thickening, and the efficiency of the initiator can be further improved. Further, since chloroprene has a boiling point of about 59 ℃ under normal pressure, when heat is generated by abnormal polymerization or the like by setting the polymerization temperature to 55 ℃ or lower, the phenomenon of bumping of the reaction solution can be avoided without additional heat removal. It is further preferable that the polymerization temperature is kept at 5 to 20 ℃ to obtain a statistical copolymer having excellent mechanical properties and containing a chloroprene monomer unit and an unsaturated nitrile monomer unit.

The final polymerization rate in the emulsion polymerization is not particularly limited, but is preferably 80% or less in order to prevent gelation. For the purpose of modifying a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit, a gel may be produced in a constant amount, and the polymerization rate in this case is not particularly limited, but is preferably 70% or more, preferably 80% or more, from the viewpoint of economy. For example, a latex of a statistical copolymer having a high gel content and containing a chloroprene monomer unit and an unsaturated nitrile monomer unit is excellent in mechanical strength, heat resistance and chemical resistance. Further, the composition containing the statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit, which contains a gel component, is excellent in dimensional stability at sheet processing and discharge property at extrusion processing. The polymerization rate can be adjusted by adding a polymerization inhibitor to stop the polymerization reaction. The polymerization inhibitor is not particularly limited, and examples thereof include: oil-soluble polymerization inhibitors, i.e., thiodiphenylamine, 4-tert-butylcatechol, 2-methylenebis-4-methyl-6-tert-butylphenol, water-soluble polymerization inhibitors, i.e., diethylhydroxylamine, and the like.

The removal of the unreacted monomer can be carried out by a known method such as heating under reduced pressure. Thereafter, the solid statistical copolymer can be recovered by adjusting the pH, and subjecting the resulting mixture to freezing, water washing, hot air drying, and the like.

However, in the examples of patent document 3, a chloroprene copolymer produced by adding monomers such as a chloroprene monomer and an acrylonitrile monomer together is described. In this example, the oil resistance of the vulcanizate was evaluated by measuring the volume increase (%) after immersing the vulcanizate of the chloroprene copolymer in oil at 100 ℃ for 72 hours. Table 3 of patent document 3 shows that the oil resistance of the vulcanizate is 45.0% or more.

On the other hand, as shown in examples described later, the results of the oil resistance test of sulfides including the statistical copolymer were 19% and 5%. In the oil resistance test of this example, the volume increase (%) after immersing the sulfide in 135 ℃ oil for 72 hours was measured. The temperature of the oil in the oil resistance test of this example is higher than that of patent document 3, and although it is a severe condition, the volume increase rate is significantly small.

<2 > statistical copolymer >

A second embodiment is a statistical copolymer having a specific composition comprising chloroprene monomer units and unsaturated nitrile monomer units. The statistical copolymer including the chloroprene monomer unit and the unsaturated nitrile monomer unit of the present embodiment can be obtained by the above-described production method, but is not limited to the present production method.

The amount of unsaturated nitrile bonded in the statistical copolymer is preferably 5 to 40 mass%. By setting the amount to such a range, a vulcanized rubber having practically useful oil resistance and mechanical strength can be obtained, and therefore a suitable statistical copolymer can be obtained. The amount of the unsaturated nitrile bonded to the statistical copolymer is more preferably 8 to 20% by mass, and further preferably 8 to 17% by mass in view of low-temperature characteristics. When the amount of the unsaturated nitrile incorporated is more than 20% by mass or more than 17% by mass, the low-temperature characteristics (low-temperature compression set) of the statistical copolymer may be lowered.

From the viewpoint of particularly excellent oil resistance and mechanical properties of the vulcanized rubber, it is particularly preferably 12 to 20% by mass, and from the viewpoint of low-temperature characteristics, it is more preferably 12 to 17% by mass. On the other hand, from the viewpoint of satisfying both excellent oil resistance and particularly excellent low-temperature properties (low-temperature compression set), 8 to 12% by mass is preferable.

The number average molecular weight (Mn) of the statistical copolymer is not particularly limited, and is preferably in the range of 8 to 30 ten thousand. When the amount is less than 8 ten thousand, mechanical properties of the vulcanized molded article may be deteriorated, and when the amount is more than 30 ten thousand, moldability of the resulting rubber composition may be deteriorated. Similarly, the molecular weight distribution, i.e., the mass average molecular weight/number average molecular weight (Mw/Mn), is not particularly limited, but is generally in the range of 1.5 to 5.0.

Examples of the statistical copolymer of the present embodiment include a chloroprene-acrylonitrile statistical copolymer, a chloroprene-methacrylonitrile statistical copolymer, a chloroprene-ethacrylonitrile statistical copolymer, and a chloroprene-phenylacrylonitrile statistical copolymer. Among them, chloroprene-acrylonitrile statistical copolymers are preferred from the viewpoint of ease of production, oil resistance and mechanical strength.

The statistical copolymer of the present embodiment is a statistical copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, and is characterized in that when a vulcanized rubber produced according to the sample production condition (I) is evaluated, the conditions that the oil resistance to IRM903 oil measured according to JISK6258 is preferably Δ W < + 15%, more preferably Δ V < + 20% or less are satisfied, the compression set at 0 ℃ after 72 hours measured according to JIS K6262 is 25% or less, more preferably 20% or less, and the bending fatigue resistance at 40 ℃ measured according to JIS K6260 is 10 ten thousand or more are satisfied. Further, in the case of evaluating the vulcanized rubber produced under the sample production condition (I), the statistical copolymer of the present embodiment may have the following mechanical properties measured according to JIS K6251: the breaking strength is more than 20MPa, and the breaking elongation is more than 300%.

(sample preparation Condition (I))

A statistical copolymer (100 parts by mass), 4 '-bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine (e.g., "NORAC CD" manufactured by Nippon Kogyo chemical industries Co., Ltd.), 2 parts by mass of magnesium oxide (e.g., "Kyowamag # 150" manufactured by Kyowa chemical industries Co., Ltd.), 50 parts by mass of carbon black (e.g., "SRF"; ASAHI CARBON., LTD. "ASAHI # 50") 5 parts by mass of a polyether ester plasticizer (e.g., "AdekacizerRS-735" manufactured by ADEKA Co., Ltd.), 5 parts by mass of zinc oxide (e.g., made by Sakai chemical industries Co., Ltd.), 1.5 parts by mass of ethylthiourea (e.g., "Accel 22S" manufactured by Kakoo chemical industries Co., Ltd.), 1.5 parts by mass of N-phenyl-N' - (1, 3-dimethylbutyl) -p-phenylenediamine (e.g., "RAC 6C" manufactured by Nippon Kogyo chemical industries Co., Ltd.) was kneaded for 20 minutes using an 8-inch roll, a rubber composition was obtained. The obtained rubber composition was subjected to heat treatment at 170 ℃ for 20 minutes by an electric hot press and then at 170 ℃ for 2 hours in heated air in accordance with JIS K6250 to prepare a vulcanized rubber.

<3. latex >

The latex of the third embodiment is a latex containing a statistical copolymer having a specific composition comprising chloroprene monomer units and unsaturated nitrile monomer units. In addition, the latex comprises: a latex containing the above-mentioned statistical copolymer produced by the emulsion polymerization described in the above-mentioned method for producing a statistical copolymer. The unreacted monomer contained in the latex after the polymerization reaction is preferably removed by a known method such as heating under reduced pressure.

The solid content concentration of the latex of the present embodiment is preferably 30 to 70% by mass in the total amount of the latex. By setting the content in such a range, a latex which is suitable for production and has excellent storage stability can be obtained. The method for measuring the solid content concentration is not particularly limited, and can be calculated from the mass change before and after drying when the latex containing the statistical copolymer is dried in a hot air dryer for 3 hours.

The latex of the present embodiment is suitably used for adhesives and dipped goods (see patent documents 6 and 7 and non-patent document 1). Rubber latex containing synthetic rubber such as natural rubber, CR, IR (isoprene rubber), NBR and the like is used as a raw material for dip-molded products such as medical surgical gloves, examination gloves, industrial gloves, balloons, catheters, rubber boots, reinforcing fibers and the like. In particular, synthetic rubbers such as CR, IR, NBR and the like are preferable as the rubber latex for medical surgical gloves, examination gloves, industrial gloves and household gloves, in order to avoid the problem of shock symptoms (allergic reaction) caused by allergy to natural rubber. Among them, CR gloves are used in food factories, machinery factories, and the like because they are excellent in balance between flexibility and mechanical strength and exhibit high oil resistance. In recent years, thin gloves have been demanded vigorously from the viewpoint of workability, but there is a problem that strength and oil resistance are reduced along with this. In addition, in order to reduce allergy derived from a vulcanization accelerator, development of gloves free from a vulcanization accelerator has been advanced, and reduction in strength and oil resistance has been a technical problem. In addition, in order to improve adhesion to rubber, CR is also used in RFL which is impregnated with reinforcing fibers and surface-treated. In the belt applications as the application field of the reinforcing fiber, as described above, the demand for mechanical strength and oil resistance is high. Therefore, development of a polychloroprene latex having further excellent mechanical strength and oil resistance has been desired. The latex contains the statistical copolymer, and therefore, the mechanical strength and oil resistance of the adhesive and dipped article can be improved. This enables production of an adhesive and an impregnated product superior to those of conventional CR.

<4 > rubber composition

The rubber composition of the fourth embodiment contains: a statistical copolymer having a specific composition comprising chloroprene monomer units and unsaturated nitrile monomer units. The statistical copolymer contained in the rubber composition can be obtained by dehydrating and drying the latex. In the rubber composition of the present embodiment, the raw materials other than the statistical copolymer are not particularly limited and may be appropriately selected depending on the purpose and the application. Examples of the raw materials that can be contained in the rubber composition include a vulcanizing agent, a vulcanization accelerator, a filler or a reinforcing agent, a plasticizer, a processing aid, a lubricant, an antioxidant, a silane coupling agent, and the like.

As the vulcanizing agent that can be added, sulfur, thiourea-based, guanidine-based, thiuram-based, and thiazole-based organic vulcanizing agents generally used for vulcanizing chloroprene rubber can be used, and thiourea-based vulcanizing agents are preferred. Examples of the thiourea-based vulcanizing agent include ethylthiourea, diethylthiourea, trimethylthiourea, triethylthiourea, and N, N' -diphenylthiourea, and trimethylthiourea and ethylthiourea are particularly preferable. Further, a vulcanizing agent such as 3-methylthiazolidinethione, dimethylammonium hydrogen isophthalate, 1, 2-dimercapto-1, 3, 4-thiadiazole derivative, or N-cyclohexylthiophthalimide may be used. These vulcanizing agents may be used in combination of 2 or more of those listed above. As the vulcanizing agent, simple metals such as beryllium, magnesium, zinc, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, bismuth, molybdenum, tungsten, tellurium, selenium, iron, nickel, cobalt, and osmium, and oxides and hydroxides of these metals can be used. Among these vulcanizing agents which can be added, calcium oxide, zinc oxide, antimony dioxide, antimony trioxide and magnesium oxide are particularly preferable because of their high vulcanizing effect. These vulcanizing agents may be used in combination of 2 or more. The vulcanizing agent is preferably added in a range of 0.1 parts by mass or more and 10 parts by mass or less in total with respect to 100 parts by mass of the rubber component.

The filler or reinforcing agent is added for adjusting the hardness of the rubber or improving the mechanical strength, and is not particularly limited, and examples thereof include furnace carbon blacks such as SAF, ISAF, HAF, EPC, XCF, FEF, GPF, HMF, and SRF, modified carbon blacks such as hydrophilic carbon blacks, channel carbon blacks, soot blacks, thermal cracking carbons such as FT and MT, acetylene blacks, Ketjen blacks, silica, clay, talc, and carbonic acidCalcium. The other inorganic filler is not particularly limited, and alumina (Al) such as γ -alumina and α -alumina can be used₂O₃) Aluminum oxide monohydrate (Al) such as boehmite and diaspore₂O₃·H₂Aluminum hydroxide [ Al (OH) ] such as O), gibbsite and bayerite₃]Aluminum carbonate [ Al ]₂(CO₃)₂]Magnesium hydroxide [ Mg (OH) ]₂]Magnesium carbonate (MgCO)₃) Talc (3 MgO.4SiO)₂·H₂O), attapulgite (5 MgO.8SiO)₂·9H₂O), titanium white (TiO)₂) Titanium black (TiO)_2n-1) Calcium oxide (CaO), calcium hydroxide [ Ca (OH) ]₂]Aluminum magnesium oxide (MgO. Al)₂O₃) Clay (Al)₂O₃·2SiO₂) Kaolin (Al)₂O₃·2SiO₂·2H₂O), pyrophyllite (Al)₂O₃·4SiO₂·H₂O), bentonite (Al)₂O₃·4SiO₂·2H₂O), aluminum silicate (Al)₂SiO₅、Al₄·3SiO₄·5H₂O, etc.), magnesium silicate (Mg)₂SiO₄、MgSiO₃Etc.), calcium silicate (Ca)₂SiO₄Etc.), calcium aluminum silicate (Al)₂O₃·CaO·2SiO₂Etc.), calcium magnesium silicate (CaMgSiO)₄) Calcium carbonate (CaCO)₃) Zirconium oxide (ZrO)₂) Zirconium hydroxide [ ZrO (OH) ]₂·nH₂O]Zirconium carbonate [ Zr (CO) ]₃)₂]Crystalline aluminosilicates containing hydrogen for correcting charge, such as hydrotalcite and various zeolites, and alkali metal or alkaline earth metal. The filler and the reinforcing agent may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The amount of these fillers and reinforcing agents to be blended may be adjusted depending on the physical properties of the rubber composition and the vulcanized molded product thereof required, and is not particularly limited, and may be added in a range of usually 15 parts by mass or more and 200 parts by mass or less in total to 100 parts by mass of the rubber component in the rubber composition of the present embodiment.

The plasticizer is not particularly limited as long as it is a plasticizer having compatibility with rubber, and examples thereof include: vegetable oils such as rapeseed oil, linseed oil, castor oil, and coconut oil, phthalate plasticizers, DUP (di (undecyl) phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DOTP (dioctyl terephthalate), DOS (dioctyl sebacate), DBS (dibutyl sebacate), DOA (dioctyl adipate), DINCH (1, 2-cyclohexane dicarboxylic acid diisononyl ester), TOP (trioctyl phosphate), TBP (tributyl phosphate), ester plasticizers, ether ester plasticizers, thioether plasticizers, aromatic oils, naphthenic oils, lubricating oils, process oils, paraffin waxes, liquid paraffin, vaseline, and petroleum pitches, 1 or more may be used depending on the properties required for the rubber composition of the present embodiment, the vulcanization molded product of the composition. The amount of the plasticizer to be blended is not particularly limited, and may be added in a range of usually 5 parts by mass or more and 50 parts by mass or less in total to 100 parts by mass of the rubber component in the rubber composition of the present embodiment.

When the rubber composition is kneaded or vulcanization molded, examples of the processing aid and lubricant to be added for improving processing characteristics and surface lubricity such as easy peeling from a roll, a molding die, a screw of an extruder, and the like include fatty acids such as stearic acid, paraffin-based processing aids such as polyethylene, fatty acid amides, and the like. The processing aid and the lubricant may be used in a single amount of 1 or in combination of 2 or more. The amount of addition is not particularly limited, and is usually 0.5 parts by mass or more and 5 parts by mass or less in total to 100 parts by mass of the rubber component in the rubber composition of the present embodiment.

As the antioxidant for improving heat resistance, a primary antioxidant which is used in general rubber applications and which captures radicals to prevent autoxidation and a secondary antioxidant which makes hydroperoxides harmless may be added. These antioxidants may be added in a proportion of 0.1 part by mass or more and 10 parts by mass or less, preferably 2 parts by mass or more and 5 parts by mass or less, with respect to 100 parts by mass of the rubber component in the rubber composition. These antioxidants may be used alone, or in combination of 2 or more. Examples of the primary antioxidant include phenol antioxidants, amine antioxidants, acrylate antioxidants, imidazole antioxidants, metal carbamates, and waxes. Examples of the secondary antioxidant include a phosphorus antioxidant, a sulfur antioxidant, and an imidazole antioxidant. Examples of the antioxidant include, but are not particularly limited to, N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4 ' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine, p- (p-toluenesulfonylamide) diphenylamine, N ' -di-2-naphthyl-p-phenylenediamine, N ' -diphenyl-p-phenylenediamine, N-phenyl-N ' -isopropyl-p-phenylenediamine, N-phenyl-N ' - (1, 3-dimethylbutyl) -p-phenylenediamine, N-phenyl-N ' - (3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, 1, 3-tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, N-phenylthionylamine, N-phenyldiamine, N-methyl-N ' - (3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, 4,4 ' -butylidenebis- (3-methyl-6-tert-butylphenol), 2-thiobis (4-methyl-6-tert-butylphenol), 7-octadecyl-3- (4 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) propionate, tetrakis [ methylene-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate ] methane, pentaerythritol-tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate ], 1, 6-hexanediol-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2, 4-bis (N-octylthio) -6- (4-hydroxy-3, 5-di-tert-butylanilino) -1,3, 5-triazine, tris- (3, 5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, 2-thio-diethylene bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxy) -hydrocinnamide, 2, 4-bis [ (octylthio) methyl ] -o-cresol, 3, 5-di-tert-butyl-4-hydroxybenzyl-phosphonate-diethyl ester, and mixtures thereof, Tetrakis [ methylene (3, 5-di-tert-butyl-4-hydroxyhydrocinnamate) ] methane, octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate and 3, 9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy } -1, 1-dimethylethyl ] -2,4,8, 10-tetraoxaspiro [5.5] undecane, tris (nonylphenyl) phosphite, tris (mixed mono-and di-nonylphenyl) phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, diphenyl monotridecyl phosphite, Diphenyl nonylphenyl phosphite, triphenyl phosphite, tris (tridecyl) phosphite, triisodecyl phosphite, tris (2-ethylhexyl) phosphite, tris (2, 4-di-tert-butylphenyl) phosphite, tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite, 1, 3-tris (2-methyl-4-ditridecyl phosphite-5-tert-butylphenyl) butane, 4 ' -butylidenebis (3-methyl-6-tert-butyl-ditridecyl phosphite), 2 ' -ethylidene bis (4, 6-di-tert-butylphenol) fluorophosphite, 4 ' -isopropylidene-diphenylphenalkyl (C12-C15) phosphite, tri (iso-decyl) phosphite, tri (2-ethylhexyl) phosphite, tris (2-methyl-4-ditridecyl) phosphite, tri (2-ethyl-butyl-phenyl) phosphite, tri (2-tert-butylphenyl) phosphite, Cyclic neopentane-tetraylbis (2, 4-di-t-butylphenyl phosphite), cyclic neopentane-tetraylbis (2, 6-di-t-butyl-4-phenyl phosphite), cyclic neopentane-tetraylbis (nonylphenyl phosphite), bis (nonylphenyl) pentaerythritol diphosphite, dibutyl hydrogen phosphate, distearyl pentaerythritol diphosphite, hydrogenated bisphenol a pentaerythritol phosphite polymer, 2-mercaptobenzimidazole, and the like.

In order to improve the adhesion between the rubber component such as the statistical copolymer and the natural rubber and the filler and the reinforcing agent and improve the mechanical strength, a silane coupling agent may be further added. The silane coupling agent may be added at the time of kneading the rubber composition, or may be added in the form of a surface treatment of the filler or reinforcing agent in advance. The silane coupling agent may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The following are not particularly limited, and examples thereof include: bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (3-trimethoxysilylpropyl) tetrasulfide, bis- (3-methyldimethoxysilylpropyl) tetrasulfide, bis- (2-triethoxysilylethyl) tetrasulfide, bis- (3-triethoxysilylpropyl) disulfide, bis- (3-trimethoxysilylpropyl) disulfide, bis- (3-triethoxysilylpropyl) trisulfide, 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, the like, 3-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropyl-benzothiazoletetrasulfide, 3-trimethoxysilylpropyl-methacryloylmonosulfide, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, isobutyltrimethoxysilane, N-decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, phenyltrimethoxysilane, dimethyltrimethoxysilane, dimethylmethoxysilane, dimethyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, octadecylmethyldimethoxysilane, octadecyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, triphenylchlorosilane, pentadecylfluorodecylmethyldichlorosilane, pentadecylfluorodecyltrichlorosilane, triethylchlorosilane and the like.

The rubber composition can be produced by a conventional method using a known machine or apparatus.

The rubber composition of the present embodiment contains the statistical copolymer, and therefore, is excellent in oil resistance, low-temperature compression set, and bending fatigue resistance. In addition, it may have excellent mechanical strength.

<5. vulcanized molded article >

The vulcanized molded article of the fifth embodiment is produced by vulcanizing the composition containing the rubber composition. The vulcanized molded product of the present embodiment is excellent in oil resistance because the statistical copolymer is used. In addition, it may have excellent mechanical strength.

The vulcanization temperature may be appropriately set depending on the composition, and may be set to 130 to 230 ℃. The vulcanization time may be appropriately set depending on the composition and shape, and may be set to 10 to 90 minutes, for example. The molding method is also not particularly limited, and known methods such as press molding, extrusion molding, injection molding, and calender molding can be used. In addition, the second vulcanization is carried out at 150 to 200 ℃ as required, whereby the compression set can be improved.

The vulcanized molded article of the present embodiment is a vulcanized molded article using a statistical copolymer of a chloroprene monomer unit and an unsaturated nitrile monomer unit, the content of the unsaturated nitrile monomer unit (in the present specification, sometimes referred to as a bonding amount) being 8 to 20 mass%.

Further, the vulcanized molded product of the present embodiment has an oil resistance Δ W < 15% against IRM903 oil as measured in accordance with JIS K6258.

The vulcanized molded product of the present embodiment has a compression set of 25% or less after 72 hours at 0 ℃ as measured according to JIS K6262.

The vulcanized molded product of the present embodiment has a bending fatigue resistance at 40 ℃ of 10 ten thousand or more as measured according to JIS K6260.

Further, the mechanical properties of the vulcanized molded article according to the present embodiment may be such that the strength at break is >20MPa and the elongation at break is > 300%, as measured according to JIS K6251.

The most preferred vulcanized molded article of the present embodiment is a vulcanized molded article comprising a statistical copolymer of a chloroprene monomer unit and an unsaturated nitrile monomer unit having a content of the unsaturated nitrile monomer unit (in this specification, sometimes referred to as a bonding amount) of 8 to 12 mass%. The vulcanized molded article can have particularly excellent low-temperature properties such that the oil resistance to IRM903 oil measured in accordance with JIS K6258 is Δ W < + 15%, and the compression set after 72 hours at 0 ℃ measured in accordance with JIS K6262 is 20% or less. Therefore, the present invention can be suitably used for the following applications, and can be suitably used as a sealing member or a hose.

The statistical copolymer, the latex and the rubber composition containing the statistical copolymer, and the vulcanized molded article obtained by vulcanizing the composition containing the rubber composition according to the present embodiment can be suitably used for a transmission belt, a conveyor belt, a hose, a wiper, a dipped product, a sealing member, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber, and a sponge product.

(conveyor belt and Transmission Belt)

The conveyor belt is a wide belt used for a belt conveyor or the like, and is used for conveying articles or the like. The transmission belt is a mechanical element for winding the transmission device, and is a member for transmitting power from the driving pulley to the driven pulley. A transmission belt is often used by being applied to a pulley attached to a shaft. The transmission belt is excellent in lightweight property, quietness, freedom of shaft angle, and the like, and therefore is widely used in the entirety of machines for automobiles, general industries, and the like. The types of transmission belts have also been diversified, and flat belts, timing belts, V-belts, ribbed belts, circular belts, and the like are used in different ways depending on the mechanical use. In order to transmit power efficiently, a belt applied with high tension repeats rotational deformation, and therefore, an elastomer material such as NR (natural rubber), SBR (styrene butadiene rubber), CR (chloroprene rubber), NBR (nitrile rubber), HNBR (hydrogenated nitrile rubber) is used for the conveyor belt and the transmission belt. Since CR has excellent rubber properties and oil resistance, it is used for various conveyor belts, automobiles, general industrial transmission belts, and the like, and it is a technical problem to improve mechanical properties in order to withstand high tension. Further, in some cases, a transmission belt of a working machine used in a construction site is used in an environment exposed to scattered oil, and further improvement in oil resistance is required. Further, since the belt is continuously used in a dynamic environment, a material having excellent bending fatigue resistance is required for improving the reliability of the product.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance, and bending fatigue resistance of the conveyor belt and the transmission belt. This makes it possible to manufacture a belt that is difficult to use with conventional CR and that can be used even in an environment exposed to scattered oil.

(Flexible pipe)

The flexible pipe is a bendable pipe, and is used for operations such as watering and the like which are free to bend and require portability and mobility. Further, since fatigue failure due to deformation is less likely to occur than in a hard pipe such as a metal pipe, it is used for piping in a portion accompanied by vibration such as piping of an automobile. Among these, the most common is a rubber hose. The rubber hose comprises: high/low pressure hoses for water supply, oil supply, air supply, steam supply, and oil pressure, and the like, made of NR, CR, EPDM (ethylene propylene diene rubber), SBR, NBR, ACM (acrylic rubber), AEM (ethylene acrylic rubber), HNBR, ECO (epichlorohydrin rubber), FKM (fluororubber), and the like. CR is mainly used for a high-pressure hose for hydraulic use because of its good mechanical properties capable of withstanding the pressure of a high-pressure fluid, but the inner layer is generally NBR because of insufficient oil resistance. However, it is difficult to bond CR and NBR having significantly different chemical structures, and there is a problem that if the bonding is insufficient, peeling occurs at the interface. Therefore, a material having good mechanical strength, oil resistance, and adhesiveness is desired. Further, the joint portion of the hose is tightly fitted with a hose clamp to prevent leakage of fluid, but there is a problem that the hose sags and fluid leaks due to long-term installation.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance and sag resistance (low compression set) of the hose. This makes it possible to manufacture a hose that is in direct contact with a nonpolar fluid, which is difficult with conventional CR.

(wiper)

A wiper is generally provided to wipe off and remove rainwater, muddy water, oil stains, seawater, ice, snow, dust, and the like attached to the surface of a windshield, a rear glass, and the like of an automobile, an electric car, an aircraft, a ship, a construction machine, and the like, to improve the field of view, and to ensure the safety of operation. A scraper is attached to a portion of the wiper that contacts the glass surface, and NR, CR, or the like is generally used as a material of the scraper. CR is excellent in mechanical strength capable of withstanding repeated deformation, endurance fatigue, wiping properties, and the like, and is therefore used for an automobile wiper. However, the oil resistance is insufficient, and therefore, if the rubber material swells due to oil stain, there is a problem that the wiping property is lowered. Therefore, a blade having excellent oil resistance is required in an environment with many oil stains. Since the wiper is attached by being pressed against the window, if the wiper is not operated for a long time, there is a problem that the wiper droops and wiping performance is deteriorated.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance, endurance fatigue resistance, and sagging resistance (low compression set) of the wiper. Thus, a wiper which can be used even in an environment where oil stain is large and which is difficult to use by conventional CR can be manufactured.

(dipped article)

Rubber latex containing synthetic rubber such as natural rubber, CR, IR (isoprene rubber), NBR and the like is used as a raw material for dip-molded products such as medical surgical gloves, examination gloves, industrial gloves, balloons, catheters, rubber boots, reinforcing fibers and the like. In order to avoid the problem of shock symptoms (allergic reaction) caused by natural rubber allergy, synthetic rubbers such as CR, IR, NBR and the like are particularly preferable as the rubber latex for medical surgical gloves, examination gloves, industrial gloves and household gloves. Among them, CR gloves are used in food factories, machinery factories, and the like because they are excellent in balance between flexibility and mechanical strength and exhibit high oil resistance. In recent years, thin gloves have been strongly demanded from the viewpoint of workability, but there is a problem that strength and oil resistance are reduced. In addition, gloves without vulcanization accelerators have been developed to reduce allergy derived from vulcanization accelerators, but among them, reduction in strength and oil resistance has become a technical problem. In addition, in order to improve adhesion to rubber, CR is also used in RFL which is impregnated with reinforcing fibers and surface-treated. In the belt applications as the application field of the reinforcing fiber, as described above, the demand for mechanical strength and oil resistance is high. Therefore, development of a polychloroprene latex having further excellent mechanical strength and oil resistance has been desired.

The statistical copolymer of the present embodiment can improve the mechanical strength and oil resistance of the dipped article. Thus, a thin glove and a dipped article without a vulcanization accelerator, which are difficult to use in conventional CR, can be manufactured.

(sealing Member)

The sealing member is a member for preventing leakage of liquid and gas, and intrusion of dust such as rainwater and dust and foreign matter into a machine or a device, and plays an important role in maintaining mechanical performance. The sealing component is provided with a gasket for fixing; and, a seal for the moving part/movable part. For a gasket to which a seal portion is fixed by a bolt or the like, various elastic bodies according to purposes are used for a soft gasket such as an O-ring or a rubber sheet. Further, the seal is used for a rotating portion such as a shaft of a pump or a motor or a movable portion of a valve, a reciprocating portion such as a piston, a connecting portion of a coupler, a water stop portion of a faucet, and the like. The sealing property is ensured by the elasticity of the oil sealing elastic body used for sealing a low-pressure hydraulic machine or lubricating oil. Among these elastomer sealing members, CR has good mechanical strength, and is therefore used for sealing members for polar gases and liquids. On the other hand, in order to use the sealing member for nonpolar fluid such as engine oil and gear oil, the oil resistance of CR is insufficient, and improvement is essential.

The statistical copolymer of the present embodiment can improve the mechanical strength and oil resistance of the seal member. This makes it possible to manufacture a seal member for a nonpolar fluid such as engine oil or gear oil, which is difficult to use in conventional CR. In addition to the above, the statistical copolymer of the present embodiment can provide good sag resistance (low compression set), and can provide good sealing performance, since the shape of the sealing member is not easily changed even after long-term use. In particular, sag resistance (low compression set) at low temperatures is important for the present application.

Specific examples of the seal member to which the present embodiment can be applied include an engine head gasket, an oil pan gasket, an oil seal, a lip seal, an O-ring, a transmission seal, a crankshaft, a camshaft seal, a valve stem, a power steering seal with a head seal, and the like.

(Adhesives)

CR is used as an adhesive for a wide range of materials such as civil engineering and construction, plywood, furniture, shoes, diving suits, and automobile interior materials because of its characteristics of contact property and excellent initial adhesive strength. Among them, CR is excellent in initial adhesion strength and heat-resistant adhesion strength, and thus has been greatly demanded as a one-pack type adhesive for polyurethane foam which is generally used as a raw material for furniture and automobile interior materials. High aesthetic quality is required for automobile interior trim, but since the oil resistance of CR is insufficient, when various oils and fuels used in automobiles adhere to an adherend, interfacial peeling or the surface of the adherend may be curved. Therefore, an adhesive material having high oil resistance is strongly desired.

The statistical copolymer of the present embodiment can improve the mechanical strength and oil resistance of the adhesive. This enables production of an adhesive superior to conventional CR.

(boots)

The boot is a corrugated member having an outer diameter gradually increasing from one end to the other end, and includes: a boot for a constant velocity joint boot, a boot for a ball joint boot (dust-proof boot), a boot for a rack and pinion, and the like for protecting a drive unit of an automobile drive system and the like. Since the boot is required to have physical strength capable of withstanding large deformation and oil resistance, CR is often used. In recent years, with the progress of light-weight and compact technology for vehicles, the operating space of the protective cover is reduced, and therefore, the heat removal efficiency is reduced and the thermal environment is increasingly severe. Therefore, improvement in reliability under a high-temperature atmosphere with respect to a nonpolar liquid such as oil or grease contained in the shield case is required.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance, and endurance fatigue of the boot. This makes it possible to manufacture a protective cover that is more reliable than conventional CR with respect to nonpolar liquids such as oil and grease contained therein. Further, since the sag resistance (low compression set) is also excellent, deformation of the caulking portion such as a metal band for preventing leakage of oil contained therein is less likely to occur.

(rubber cloth)

The rubber sheet is a composite material of rubber and a cloth fabric (fiber) in which rubber is bonded to the cloth, and has higher strength, water resistance, air tightness, and the like than a rubber sheet. These characteristics are utilized for various purposes, such as rubber boats, tent materials, clothes such as raincoats, waterproof sheets for buildings, and cushioning materials. As the rubber material used for the rubber blanket, CR, NBR, EPDM, and the like are generally used. Among them, CR is widely used for outdoor rubber cloths such as rubber boats because of its excellent mechanical strength and weather resistance. On the other hand, in order to use the rubber blanket sheet in an environment where oil is scattered such as in an automobile or a construction site, the oil resistance is insufficient, and improvement is required.

The statistical copolymer of the present embodiment can improve the mechanical strength and oil resistance of the blanket. This makes it possible to manufacture a rubber blanket that can be used even in an environment where oil is scattered, which is difficult with conventional CR.

(rubber roll)

The rubber roller is a roller manufactured by bonding and covering a metal core such as an iron core with rubber, and is generally manufactured by winding a rubber sheet spirally around a metal iron core. Rubber materials such as NBR, EPDM, and CR are used for the rubber roll according to the required characteristics for various applications such as paper making, iron making, and printing. CR has good mechanical strength capable of withstanding the friction of conveyed objects, and is therefore used for a wide range of roller applications. On the other hand, the rubber roller which can be used in an environment where oil adheres, such as in the production of industrial materials for iron making and paper making, and products, is insufficient in oil resistance, and improvement is required. Further, a rubber roller for conveying a heavy object has a problem of deformation due to a load, and improvement is required.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance and sag resistance (low compression set) of the rubber roller. Thus, a rubber roller usable in an environment where oil adheres thereto, which is difficult in conventional CR, can be manufactured.

(vibration-proof rubber)

The vibration-proof rubber is a rubber for preventing transmission of vibration, and is used for, for example, sound insulation, buffering of impact, and the like, and for preventing vibration waves generated from a machine from reaching the outside. For example, in automobiles and various vehicles, vibration-proof rubber is used as a constituent material of a torsional damper, an engine mount, a muffler bracket, and the like, in order to absorb vibration during driving of an engine and prevent noise. While natural rubber having excellent vibration-damping characteristics is widely used as the vibration-damping rubber, CR is used because oil resistance is required for vibration-damping rubber used in environments where oil is scattered such as for construction and heavy machinery. When the vibration-proof rubber swells due to adhesion of oil thereto, there is a problem that the mechanical strength is reduced and the rubber breaks early. In addition, in order to be used under a sports environment, improvement in durability against repeated deformation is required.

The statistical copolymer of the present embodiment can improve the mechanical strength, oil resistance, and bending fatigue resistance of the vibration-proof rubber. This makes it possible to produce a vibration damping rubber that can be used even in an environment where oil is scattered, which is difficult with conventional CR.

(sponge product)

The sponge is a porous material having numerous fine pores in the interior. The pores may take any of the forms of continuous bubbles and individual bubbles. When the pores are sufficiently large and continuous, the liquid is sucked in the pores in a manner of being replaced with air in the pores when the pores are immersed in the liquid, and the liquid is easily released when a force is applied from the outside. When the pores are small, the porous material can be used as an excellent cushioning material or heat insulator. CR has excellent mechanical strength and rubber elasticity, and is widely used for sponges, and specific examples thereof include vibration-proof members, sponge seal members, diving suits, shoes, and the like. In any applications, improvement of oil resistance is required in order to prevent swelling deformation and discoloration caused by oil.

The statistical copolymer of the present embodiment can improve the mechanical strength and oil resistance of the sponge product. Thus, a sponge product which is difficult to use in conventional CR and which is less likely to undergo swelling deformation or discoloration due to oil can be produced.