Copolymer of chloroprene monomer and unsaturated nitrile compound, composition comprising copolymer, vulcanized molded article of composition, and use of vulcanized molded article

文档序号：788745 发布日期：2021-04-09 浏览：31次中文

阅读说明：本技术 氯丁二烯单体与不饱和腈化合物的共聚物、包含共聚物的组合物、组合物的硫化成形体和硫化成形体的用途 (Copolymer of chloroprene monomer and unsaturated nitrile compound, composition comprising copolymer, vulcanized molded article of composition, and use of vulcanized molded article ) 是由石垣雄平小林直纪会泽卓大贯俊藤本光佑西野涉于 2019-07-26 设计创作，主要内容包括：提供一种可工业利用且具有充分门尼粘度的氯丁二烯与不饱和腈化合物的共聚物。具体而言,提供一种氯丁二烯单体与不饱和腈化合物的共聚物,所述共聚物的门尼粘度ML(1+4)100℃为20～80,且具有下述通式(1)或(2)所示结构的官能团。(通式(1)中,R～1表示氢、氯、取代或未取代的烷基、取代或未取代的烯基、取代或未取代的芳基、或者取代或未取代的杂环基。)(Provided is a copolymer of chloroprene and an unsaturated nitrile compound, which is industrially usable and has a sufficient Mooney viscosity. Specifically, provided is a copolymer of chloroprene monomer and unsaturated nitrile compound, the copolymer has Mooney viscosity ML (1 +)4) 20 to 80 ℃ at 100 ℃ and has a functional group having a structure represented by the following general formula (1) or (2). (in the general formula (1), R 1 Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. ))

1. A copolymer of a chloroprene monomer and an unsaturated nitrile compound, having a Mooney viscosity ML (1+4) of 20 to 80 at 100 ℃ and having a functional group having a structure represented by the following general formula (1) or (2),

in the general formula (1), R¹Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group.

2. The copolymer of claim 1, which is a statistical copolymer.

3. The copolymer according to claim 1 or 2, wherein a scorch time t5 at 125 ℃ measured according to JIS K6300 for a rubber composition produced under the following sample production conditions (I) is 15 minutes or more,

sample preparation conditions (I):

100 parts by mass of the copolymer was kneaded 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 (SRF), 5 parts by mass of a polyether ester plasticizer, 5 parts by mass of zinc oxide, 1.5 parts by mass of ethylenethiourea 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 set to 40 ℃ to obtain a rubber composition.

4. The copolymer according to any one of claims 1 to 3, wherein when a vulcanized rubber produced under the following sample production conditions (II) is evaluated,

a weight change rate Δ W measured according to JIS K6258 using IRM903 oil of less than 15%,

a compression set at 130 ℃ of 20% or less as measured according to JIS K6262,

sample preparation conditions (II):

100 parts by mass of the copolymer was kneaded 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 (SRF), 5 parts by mass of a polyether ester plasticizer, 5 parts by mass of zinc oxide, 1.5 parts by mass of ethylenethiourea and 1 part by mass of N-phenyl-N' - (1, 3-dimethylbutyl) p-phenylenediamine for 20 minutes using an 8-inch roll with a cooling water temperature set to 40 ℃ to obtain a rubber composition, and the obtained rubber composition was subjected to heat treatment at 170 ℃ for 20 minutes using electrothermal pressing based on JIS K6250 and then at 170 ℃ for 2 hours in heated air to prepare a vulcanized rubber.

5. The copolymer according to any one of claims 1 to 4, wherein the unsaturated nitrile compound has a bonding amount of 1.0 to 18.0 mass%.

6. A composition comprising the copolymer of any one of claims 1 to 5.

7. The composition of claim 6, comprising a vulcanizing agent, a vulcanization accelerator, a filler, a reinforcing agent, a plasticizer, a processing aid, a lubricant, an anti-aging agent, or a silane coupling agent.

8. The composition of claim 7, further comprising at least 1 selected from the group consisting of natural rubber, isoprene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, butadiene rubber, styrene butadiene rubber, and ethylene propylene rubber.

9. A vulcanized molded body using the composition according to any one of claims 6 to 8.

10. The vulcanization molding according to claim 9, wherein,

a breaking strength of 20MPa or more as measured according to JIS K6251,

an elongation at break of more than 300% as measured according to JIS K6251,

a weight change rate Δ W measured according to JIS K6258 using IRM903 oil of less than 15%,

the compression set at 130 ℃ measured according to JIS K6262 is 20% or less.

11. A power transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealer, a gasket, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber, a sponge article, a rubber liner or an air spring, which uses the vulcanized molded article according to claim 9 or 10.

12. A method for producing a copolymer, which comprises obtaining the copolymer according to any one of claims 1 to 5,

adding a chain transfer agent represented by the following general formula (3) or (4) to 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile compound to obtain a mass ratio [ M ] of the total monomers and the chain transfer agent at the start of polymerization]₀/[CTA]5/1-2000/1 and 100-5000 parts by mass of an aqueous solution (B) containing 0.1-10% by mass of an emulsifier are mixed and emulsified, and then radical polymerization is carried out, and when the polymerization rate reaches 5-50%, 50-5000 parts by mass of a chloroprene monomer alone or 50-5000 parts by mass of a mixture of a chloroprene monomer and an unsaturated nitrile compound is additionally added,

in the general formula (3), R²Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group; in the general formulae (3) and (4), R^3～5Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted saturated, unsaturated or aromatic groupA carbocyclic ring of a group, a substituted or unsubstituted saturated, unsaturated or aromatic heterocyclic ring, an organometallic species, or any polymer chain.

Technical Field

The present invention relates to a copolymer of a chloroprene monomer and an unsaturated nitrile compound, a composition containing the copolymer, a vulcanized molded article of the composition, and use of the vulcanized molded article.

Background

Chloroprene rubber is a general-purpose rubber used for various applications because of its excellent heat resistance, weather resistance, ozone resistance, chemical resistance, flame retardancy, and the like. The molecular weight of polychloroprene is adjusted by changing the amount of a chain transfer agent such as a mercaptan or dithioxanthogen. However, since chloroprene rubbers are produced by radical emulsion polymerization, usable chain transfer agents are limited, and it is not easy to change a terminal functional group that largely affects rubber physical properties. In recent years, attention has been paid to control of RAFT polymerization, which is one of living radical polymerization, and it has been found that it is also applicable to production of chloroprene rubber (see, for example, patent documents 1 to 3 and non-patent documents 1 and 2). These documents disclose that the control can also be performed with respect to the terminal structure.

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication No. 2002-508409

Patent document 2: japanese laid-open patent publication No. 2007-297502

Patent document 3: japanese laid-open patent publication No. 2004-115517

Non-patent document

Non-patent document 1: polymer Chemistry,2013,4,2272.

Non-patent document 2: RSC Advance,2014,4,55529.

Disclosure of Invention

Problems to be solved by the invention

However, although the above documents successfully synthesize a polymer having a narrow molecular weight distribution, they have the following problems: the obtained polymer has a small number average molecular weight, does not have a sufficient molecular weight to withstand industrial use, and is also lacking in industrial realizability with respect to an emulsification system and polymerization conditions. Further, there is a need for a chloroprene type copolymer which is not limited to a chloroprene rubber based on RAFT polymerization, but is industrially usable and has a sufficient mooney viscosity in a wide and widespread technology relating to chloroprene rubbers.

Accordingly, a main object of the present invention is to provide a copolymer of chloroprene and an unsaturated nitrile compound which is industrially usable and has a sufficient mooney viscosity.

Means for solving the problems

Specifically disclosed is a copolymer of a chloroprene monomer and an unsaturated nitrile compound, which has a Mooney viscosity ML (1+4) of 20-80 at 100 ℃ and has a functional group having a structure represented by general formula (1) or (2).

(in the general formula (1), R¹Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. )

The aforementioned copolymer may be a statistical copolymer.

The copolymer may have a scorch time t5 of 15 minutes or more at 125 ℃ measured according to JIS K6300 for a rubber composition prepared under the following sample preparation conditions (I).

Sample preparation conditions (I):

The aforementioned copolymer may be the following copolymer:

when the vulcanized rubber produced under the following sample production conditions (II) was evaluated,

a weight change rate Δ W measured according to JIS K6258 using IRM903 oil of less than 15%,

the compression set at 130 ℃ measured according to JIS K6262 is 20% or less.

Sample preparation conditions (II):

The bonding amount of the unsaturated nitrile compound in the copolymer may be 1.0 to 18.0 mass%.

The present invention provides compositions comprising the aforementioned copolymers.

The aforementioned composition may contain a vulcanizing agent, a vulcanization accelerator, a filler, a reinforcing agent, a plasticizer, a processing aid, a lubricant, an anti-aging agent or a silane coupling agent.

The aforementioned composition may further comprise at least 1 selected from the group consisting of natural rubber, isoprene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, butadiene rubber, styrene-butadiene rubber, and ethylene-propylene rubber.

The present invention provides a vulcanized molded article using the aforementioned composition.

The vulcanization molded article may be:

a breaking strength of 20MPa or more as measured according to JIS K6251,

an elongation at break of more than 300% as measured according to JIS K6251,

a weight change rate Δ W measured according to JIS K6258 using IRM903 oil of less than 15%,

the compression set at 130 ℃ measured according to JIS K6262 is 20% or less.

The present invention provides a transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a seal, a gasket, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration isolating rubber, a sponge article, a rubber lining, or an air spring, using the vulcanized molded article.

The present invention provides a method for producing a copolymer, which is a method for producing the copolymer,

adding a chain transfer agent represented by the following general formula (3) or (4) to 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile compound to obtain a mass ratio [ M ] of the total monomers and the chain transfer agent at the start of polymerization]₀/[CTA]5/1-2000/1 and 100-5000 parts by mass of an aqueous solution (B) containing 0.1-10% by mass of an emulsifier are mixed and emulsified, and then radical polymerization is performedWhen the polymerization rate reaches 5 to 50%, 50 to 5000 parts by mass of a chloroprene monomer alone or 50 to 5000 parts by mass of a mixture of a chloroprene monomer and an unsaturated nitrile compound are additionally added.

(in the general formula (3), R²Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. In the general formulae (3) and (4), R^3～5Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted saturated, unsaturated or aromatic carbocyclic ring, a substituted or unsubstituted saturated, unsaturated or aromatic heterocyclic ring, an organometallic species, or any polymer chain. )

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there is provided an industrially usable copolymer of chloroprene and an unsaturated nitrile compound having a sufficient mooney viscosity. Further, by using the copolymer, a rubber composition having a practically sufficient scorch time can be obtained. Further, by using the copolymer, a vulcanized molded article excellent in oil resistance and rubber properties can be obtained.

Drawings

FIG. 1 shows the chloroprene-acrylonitrile statistical copolymer obtained in example 1¹Graph of H-NMR spectrum.

Detailed Description

The present embodiment will be described in detail below. The present invention is not limited to the embodiments described below.

The copolymer of a chloroprene monomer and an unsaturated nitrile compound (hereinafter, sometimes simply referred to as "copolymer") according to the present embodiment is a copolymer having a mooney viscosity ML (1+4) of 20 to 80 at 100 ℃ and having a functional group having a structure represented by the following general formula (1) or (2).

In the above general formula (1), R¹Represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group.

The chloroprene monomer is 2-chloro-1, 3-butadiene. In some cases, a small amount of 1-chloro-1, 3-butadiene may be contained as an impurity in commercially available 2-chloro-1, 3-butadiene. Such 2-chloro-1, 3-butadiene containing a small amount of 1-chloro-1, 3-butadiene may also be used as the chloroprene monomer of the present embodiment.

Examples of the unsaturated nitrile compound include acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenylacrylonitrile, and 1 kind of the unsaturated nitrile compound may be used alone or two or more kinds may be used in combination. Among these, acrylonitrile is preferable from the viewpoint of ease of production and oil resistance.

The copolymer of a chloroprene monomer and an unsaturated nitrile compound described in this embodiment is more preferably a statistical copolymer.

The functional group having a structure represented by the above general formula (1) is introduced into the copolymer of the present embodiment by radical polymerization in the presence of a chain transfer agent represented by the following general formula (3). The functional group having a structure represented by the above general formula (2) is introduced into the copolymer of the present embodiment by radical polymerization in the presence of a chain transfer agent represented by the following general formula (4). In this case, R in the following general formula (4) is bonded to a functional group having a structure represented by the above general formula (2)⁴Or R⁵In the case of any one of the groups, and R⁴And R⁵Is not bonded. They are represented by R in the following general formula (4)⁴Or R⁵The group (b) varies.

In the above general formula (3), R²Represents hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstitutedThe substituted alkenyl group, the substituted or unsubstituted aryl group, or the substituted or unsubstituted heterocyclic group is R of the above general formula (1)¹And a substituent introduced into the polymer chain. In the general formulae (3) and (4), R^3～5Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted saturated, unsaturated or aromatic carbocyclic ring, a substituted or unsubstituted saturated, unsaturated or aromatic heterocyclic ring, an organometallic species, or any polymer chain.

The chain transfer agent represented by the above general formula (3) is not particularly limited, and general compounds can be used, and examples thereof include dithiocarbamates and dithioesters. Among these, preferred are benzyl 1-pyrroledithiocarbamate (common name: benzyl 1-pyrroledithiocarbamate), 1-benzyl-N, N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazolium dithiocarbamate (common name: 1-phenylethylimidazolium dithiocarbamate), benzyl 1- (2-pyrrolidinone) dithiocarbamate (common name: benzyl 1- (2-pyrrolidinone) dithiocarbamate), benzyl phthalimidyldithiocarbamate (common name: benzyl phthalimidyldithiocarbamate), and 2-cyanoprop-2-yl-1-pyrroledithiocarbamate (common name: 2-cyanoprop-2-yl-1-pyrroledicarbamate) from the viewpoint of excellent polymerization controllability -2-yl-1-pyrrole dithiocarbamate), 2-cyanobut-2-yl-1-pyrrole dithiocarbamate (common name: 2-cyanobut-2-yl-1-pyrrole dithiocarbamate), benzyl 1-imidazole dithiocarbamate (common name: benzyl 1-imidazodithiocarbamate), 2-cyanoprop-2-yl-N, N-dimethyldithiocarbamate, benzyl N, N-diethyldithiocarbamate, cyanomethyl 1- (2-pyrrolidinone) dithiocarbamate, 2- (ethoxycarbonylbenzyl) propan-2-yl-N, N-diethyldithiocarbamate, benzyl dithiocarbamate, 1-phenylethyldithiobenzoate, 2-phenylprop-2-yl dithiobenzoate, 1-acetoxy-1-yl-ethyldithiobenzoate, 1- (4-methoxyphenyl) ethyldithiobenzoate, benzyl dithioacetate, ethoxycarbonylmethyldithioacetate, methyl-N, N-diethyldithiocarbamate, benzyl 1- (2-pyrrolidinone) dithiobenzoate, benzyl-N-ethyldithiobenzoate, benzyl-N-, 2- (ethoxycarbonyl) propan-2-yldithiocarbenzoate, 2-cyanopropan-2-yldithiocarbenzoate, dithiobenzoate, tert-butyl dithiobenzoate, 2,4, 4-trimethylpentan-2-yldithiocarbenzoate, 2- (4-chlorophenyl) -propan-2-yldithiocarbenzoate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyl diethoxyphosphinyldithiocarbamate, tert-butyl trithioperoxybenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, 1-methyl-1-phenyl-ethyl naphthalene-1-carboxylate, 2-cyanophenyl-ethyl dithiobenzoate, 2-methyl-2-yl-4-chlorodithiobenzoate, and mixtures thereof, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid, dibenzyl tetrathioterephthalate, carboxymethyldithiobenzoate, poly (ethylene oxide) having a dithiobenzoate end group, poly (ethylene oxide) having a 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid end group, 2- [ (2-phenylethylthio) sulfanyl ] propanoic acid, 2- [ (2-phenylethylthio) sulfanyl ] succinic acid, potassium 3, 5-dimethyl-1H-pyrazole-1-dithiocarbamate, cyanomethyl- (phenyl) dithiocarbamate, thiobenzoic acid, thiopropionic acid, 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, 2-chloro-2-butenyl dithiobenzoate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3, 5-dimethyl-1H-pyrazole-1-dithioformate, benzyl chloride, Cyanomethyl (phenyl) dithiocarbamate.

The chain transfer agent represented by the above general formula (4) is not particularly limited, and general compounds can be used, and examples thereof include 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2- [ [ (butylthio) thiomethyl ] thio ] propanoic acid, 2- [ [ (dodecylthio) thiomethyl ] thio ] propanoic acid, 2- [ [ (butylthio) thiomethyl ] thio ] succinic acid, 2- [ [ (dodecylthio) thiomethyl ] thio ] -2-methylpropanoic acid, 2' - [ methylthiobis (thio) ] bis [ 2-methylpropanoic acid ], 2-amino-1-methyl-2-oxoethylbutyltrithiocarbonate, and the like, Trithiocarbonates such as benzyl-2- [ (2-hydroxyethyl) amino ] -1-methyl-2-oxoethyl trithiocarbonate, 3- [ [ [ (tert-butyl) thio ] thiomethyl ] thio ] propanoic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyl trithiocarbonate and dibutylaminobenzyltrithiocarbonate.

It is clear from the general literature on RAFT polymerisation (aust. j. chem.2009,62, 1402-1472): part of the structure of the chain transfer agent used is introduced into the polymer in the form of functional groups. The presence of the functional group in the copolymer of the present embodiment can be confirmed by any method, for example, by¹H-NMR method or¹³And confirmed by C-NMR method. Is difficult to pass through¹When the functional group is detected by H-NMR, a compound having higher detection sensitivity can be used¹³C-NMR method (J.Polym.Sci., Part A: Polym.Chem.,2009,47,3118-3130, etc.) by a sufficient number of accumulations¹³The presence of functional groups was confirmed by C-NMR. That is, the presence of the functional group represented by the above general formula can be confirmed by performing the same measurement by those skilled in the art and the like for the copolymer obtained by using the chain transfer agent represented by the general formula (3) or (4) containing carbon 13 in a rich state.

The number average molecular weight Mn of the copolymer of the present embodiment is preferably 5 to 30 ten thousand, more preferably 8 to 15 ten thousand, further preferably 8 to 14 ten thousand, and particularly preferably 10 to 14 ten thousand. The copolymer having a number average molecular weight Mn of 5 ten thousand or more sufficiently exhibits mechanical properties industrially practical. Further, the copolymer having a number average molecular weight Mn of 30 ten thousand or less is excellent in kneading property and molding processability, and a vulcanized rubber using the copolymer can be more easily synthesized.

The copolymer of the present embodiment preferably has a molecular weight distribution Mw/Mn, which is the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, of 1.5 to 5.0, more preferably 2.0 to 5.0. When the molecular weight distribution Mw/Mn is 1.5 or more, it is suitable for industrial use. On the other hand, it is technically difficult to adjust the molecular weight distribution Mw/Mn to more than 5.0.

The weight average molecular weight Mw and the number average molecular weight Mn are values measured by Gel Permeation Chromatography (GPC), and the details of the measurement conditions are described in the column of examples described below.

The copolymer of the present embodiment may further contain a monomer copolymerizable with the chloroprene monomer or the unsaturated nitrile compound within a range not to impair the effects of the present embodiment. Examples of such monomers include acrylic acid, methacrylic acid; esters of acrylic acid such as methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; esters of methacrylic acid such as methyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate; hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxymethyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate; 2, 3-dichloro-1, 3-butadiene, 1-chloro-1, 3-butadiene, isoprene, ethylene, styrene, and the like. In the copolymer of the present embodiment, the monomer copolymerizable with the chloroprene monomer or the unsaturated nitrile compound is preferably at least 1 selected from the group consisting of 2, 3-dichloro-1, 3-butadiene, 1-chloro-1, 3-butadiene, acrylic acid esters, methacrylic acid esters, acrylamide and aromatic vinyl compounds, more preferably 2, 3-dichloro-1, 3-butadiene and/or aromatic vinyl compounds, and still more preferably 2, 3-dichloro-1, 3-butadiene and/or styrene.

In the present specification, the copolymer is preferably a statistical copolymer. "statistical copolymer" means: the copolymer of the distribution of the monomer chains can be described by a Bernoulli statistical model or by a first or second order Markov statistical model, as described in J.C. random "POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method" Academic Press, New York, 1977, pages 71-78. In the case where the statistical copolymer including a chloroprene monomer and an unsaturated nitrile compound according to the present embodiment is composed of a binary monomer, the reactivity ratios r1 and r2 in the Mayo-Lewis formula (I) below with respect to a chloroprene monomer M1 may be in the range of 0.3 to 3000, and r2 may be 10^-5A range of 3.0. From another viewpoint, the term "statistical copolymer" as used herein refers to a copolymer obtained by radical polymerization using a plurality of monomers. This "statistics is altogetherThe term "copolymer" essentially includes the concept of random copolymers.

[ mathematical formula 1]

The copolymer of the present embodiment can exhibit advantages in rubber production processes as described later.

The scorch time t5 at 125 ℃ measured according to JIS K6300 for a rubber composition containing the copolymer of the present embodiment prepared under the following sample preparation conditions (I) is preferably 15 minutes or more, more preferably 17 minutes or more, and still more preferably 18 minutes or more. The scorch time t5 is preferably 20 minutes or less. By setting the scorch time t5 to 15 minutes or more, the vulcanization speed can be easily adjusted by the vulcanization temperature and the additive, and both the productivity and the crosslinked structure can be improved. By setting the scorch time t5 to 20 minutes or less, the efficiency of rubber production can be further improved.

Sample preparation conditions (I):

100 parts by mass of the copolymer of the present embodiment, 2 parts by mass of 4, 4' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine (NORAC CD manufactured by Dai-Neighur chemical industries Co., Ltd.), 4 parts by mass of magnesium oxide (Kyowamag #150 manufactured by Kyowa chemical industries Co., Ltd.), and 50 parts by mass of CARBON black (SRF; ASAHI #50 manufactured by ASAHI CARBON Co., Ltd.) were measured using an 8-inch roll with the cooling water temperature set to 40 ℃, a rubber composition was obtained by kneading 5 parts by mass of a polyether ester plasticizer (Adekacizer RS-735, made by ADEKA), 5 parts by mass of zinc oxide (made by Sakai chemical Co., Ltd.), 1.5 parts by mass of ethylenethiourea (Accel 22S, made by Chuakuo chemical Co., Ltd.), and 1 part by mass of N-phenyl-N' - (1, 3-dimethylbutyl) p-phenylenediamine (NORAC 6C, made by Danei Kagaku chemical Co., Ltd.) for 20 minutes.

The bonding amount (content) of the unsaturated nitrile compound in the copolymer of the present embodiment is preferably 1.0 to 18.0 mass%. When the content is 1.0% by mass or more, the oil resistance can be improved when the rubber containing the copolymer of the present embodiment or the composition containing the rubber is vulcanized (crosslinked). When the content is 18.0% by mass or less, the rubber containing the copolymer of the present embodiment or the composition containing the rubber can exhibit good high-temperature rubber physical properties (high-temperature compression set) and low-temperature rubber physical properties (low-temperature compression set) when vulcanized (crosslinked).

When a vulcanized rubber including the copolymer of the present embodiment produced under the following sample production condition (II) was evaluated, the weight change rate Δ W measured using IRM903 oil according to JIS K6258 was less than 15%, and the compression set at 130 ℃ measured according to JIS K6262 was 20% or less.

Sample preparation conditions (II):

The bonding amount (content) of the unsaturated nitrile compound in the copolymer of the present embodiment is more preferably 5.0 to 14.0 mass%. When the content is 5.0% by mass or more, the rubber containing the copolymer of the present embodiment or the composition containing the rubber can exhibit more excellent oil resistance when vulcanized (crosslinked). When the content is 14.0% by mass or less, the rubber containing the copolymer of the present embodiment or the composition containing the rubber can exhibit more excellent high-temperature rubber physical properties (high-temperature compression set) and low-temperature rubber physical properties (low-temperature compression set) when vulcanized (crosslinked).

The copolymer of the present embodiment can be produced by the following production method.

That is, the chain transfer agent represented by the above general formula (3) or (4) is added to 100 parts by mass of the total of the chloroprene monomer and the unsaturated nitrile compound, and the mass ratio [ M ] of the whole monomers to the chain transfer agent at the start of polymerization]₀/[CTA]5/1-2000/1 and 100-5000 parts by mass of an aqueous solution (B) containing 0.1-10% by mass of an emulsifier are mixed and emulsified, and then radical polymerization is carried out, and when the polymerization rate reaches 5-50%, 50-5000 parts by mass of a chloroprene monomer alone or 50-5000 parts by mass of a mixture of a chloroprene monomer and an unsaturated nitrile compound is additionally added.

By the amount of material of all monomers at the start of the polymerization [ M]₀Amount of substance with chain transfer agent [ CTA]To achieve [ M]₀/[CTA]The polymerization controllability can be improved when the molecular weight is increased by adjusting the ratio of 5/1 to 2000/1. When the monomer ratio is less than 5/1, the chain transfer agent is separated when the emulsion is prepared, and the molecular weight distribution cannot be controlled, and when the monomer ratio is more than 2000/1, the chloroprene is free-radical polymerized by thermal polymerization, and sufficient activity cannot be obtained. [ M ] A]₀/[CTA]The value of (b) is preferably 100/1 to 500/1.

When the polymerization rate of the initially added monomer reaches 5 to 50%, the monomer is additionally added according to a desired molecular weight. If the amount is less than 5%, the free radical polymerization may progress due to formation of new micelles during polymerization, and if the amount exceeds 50%, the monomer oil droplets may disappear temporarily, and thus continuous monomer supply may be interrupted, which may cause side reactions.

The polymerization rate of the monomer to be initially added can be determined by the specific gravity of the emulsion. That is, a standard curve of the polymerization rate and the specific gravity can be prepared by performing polymerization under the same conditions in advance, sampling 3 or more points, and measuring the solid content concentration and the specific gravity.

When the monomer is added additionally, the monomer is preferably cooled in order to prevent thermal polymerization of the monomer. The means for adding is not particularly limited, and it is sufficient to add the compound directly to the system by using a pump or the like.

In order to introduce 1 or more terminal structures represented by the above general formula (1) into a molecule, a known RAFT agent can be used as a chain transfer agent. These RAFT agents are described in Japanese patent laid-open Nos. 2000-515181 and 2002-508409.

The RAFT agent is preferably a compound represented by the general formula (3), and more preferably benzyl 1-pyrroledithiocarbamate (common name: benzyl pyrroledithiocarbamate), 1-phenylethylimidazole dithiocarbamate, 3-chloro-2-butenylpyrroledithiocarbamate, 1H-pyrrole-1-dithioformate-phenylenebis-methylene, or benzyl dithiobenzoate. Further preferred is benzyl 1-pyrroledithiocarbamate (common name: benzyl pyrroledithiocarbamate).

In order to introduce 1 or more terminal structures represented by the above general formula (2) into a molecule, a compound represented by the above general formula (4) may be used as the chain transfer agent. Specific examples thereof include benzylbutyl trithiocarbonate, dibenzyltrithiocarbonate, and 2-cyano-2-propyldodecyl trithiocarbonate. Among these, benzylbutyl trithiocarbonate or dibenzyl trithiocarbonate is preferable.

The radical polymerization initiator is not particularly limited, and a persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, azo-based compound, or the like can be used, and the 10-hour half-life temperature is desirably 70 ℃ or less. When the 10-hour half-life temperature of the initiator is 70 ℃ or lower, a sufficient radical can be generated at the initial stage of polymerization, and polymerization controllability can be improved.

The emulsifier used in the emulsion polymerization is not particularly limited, and an anionic emulsifier or a nonionic emulsifier is preferable from the viewpoint of emulsion stability. In particular, the alkali metal salt of abietic acid is preferably used because the copolymer according to the present embodiment in the form of a film obtained by freeze-solidification drying after completion of polymerization has adequate strength and can prevent excessive shrinkage and breakage. Rosin acids are mixtures of resin acids, fatty acids, and the like. As the resin acid, abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid, dihydropimaric acid, dihydroisopimaric acid, secodehydroabietic acid, dihydroabietic acid, and the like are included. As the fatty acid, oleic acid, linoleic acid and the like are included. The composition of these components varies depending on the method of collecting rosin classified into gum rosin, wood rosin and tall oil rosin, the origin and tree species of pine trees, distillation purification and disproportionation (asymmetric) reaction, and is not particularly limited in the present embodiment. In view of emulsion stability and ease of handling, the emulsifier is preferably a sodium rosin acid salt or a potassium rosin acid salt.

The emulsifier concentration of the aqueous solution (B) is 0.1 to 10% by mass, and more preferably 1 to 5% by mass. If the concentration is less than 0.1 mass%, the monomers cannot be sufficiently emulsified, and if it exceeds 10 mass%, the copolymer of the present embodiment may not be precipitated smoothly when it is made into a solid state.

The amount of the emulsifier added to the aqueous solution (B) is 0.1 to 10 mass%, and is 500 to 5000 parts by mass, more preferably 600 to 4000 parts by mass, based on 100 parts by mass of all the monomers at the start of polymerization. In view of the stability of the final latex, the amount of the aqueous solution (B) to be added is preferably 100 to 200 parts by mass based on 100 parts by mass of the total monomers including the additionally added monomer.

The polymerization temperature is preferably 10 to 50 ℃. By setting the polymerization temperature to 10 ℃ or higher, the thickening of the emulsion and the efficiency of the initiator can be improved. Further, since chloroprene has a boiling point of about 59 ℃, the polymerization temperature is set to 50 ℃ or lower, and therefore, even when heat is generated by abnormal polymerization or the like, it is possible to avoid the sudden boiling of the reaction solution caused by failure to promptly remove the heat. By setting the temperature to 50 ℃ or lower for the activity, there is an advantage that the influence of the hydrolysis of the chain transfer agent and the evaporation of the monomer do not need to be considered.

The final polymerization rate in the polymerization reaction is preferably 80% or less from the viewpoint of preventing side reactions. From the viewpoint of productivity, it is more preferably 50 to 75%. By setting the molecular weight to 50% or more, a copolymer having a large molecular weight and sufficient physical properties can be obtained.

In order to adjust the final polymerization rate, when the desired polymerization rate is reached, a polymerization inhibitor for stopping the polymerization reaction may be added to stop the polymerization.

The polymerization inhibitor may be any commonly used polymerization inhibitor, and examples thereof include, but are not particularly limited to, thiodiphenylamine, 4-tert-butylcatechol, 2-methylenebis-4-methyl-6-tert-butylphenol, and diethylhydroxylamine as a water-soluble polymerization inhibitor.

Unreacted monomer can be removed by, for example, stripping. Thereafter, the copolymer of the present embodiment is obtained by adjusting the pH and performing the steps of freeze coagulation, water washing, hot air drying, and the like, which are conventional methods.

The rubber composition according to one embodiment of the present invention comprises the above-mentioned copolymer of a chloroprene monomer and an unsaturated nitrile compound. The rubber composition of the present embodiment is used for producing a crosslinked rubber or a vulcanized rubber by crosslinking or vulcanizing. The rubber composition of the present embodiment can be suitably used for producing a vulcanized rubber.

In the rubber composition of the present embodiment, the raw materials other than the copolymer are not particularly limited and may be appropriately selected depending on the purpose and use. Examples of the raw materials that can be contained in the rubber composition include a vulcanizing agent, a vulcanization accelerator, a filler, 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, or 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 ethylene thiourea, diethyl thiourea, trimethyl thiourea, triethyl thiourea, and N, N' -diphenyl thiourea, and particularly, trimethyl thiourea and ethylene thiourea are preferable. Further, a mixture of 3-methylthiazolidinethione-2-thiazole and phenylenedimaleimide, and a vulcanizing agent such as dimethylammonium isophthalate and a 1, 2-dimercapto-1, 3, 4-thiadiazole derivative may be used. These vulcanizing agents may be used in combination of two or more of the above-listed substances. In addition, elemental metals such as beryllium, magnesium, zinc, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, bismuth, molybdenum, tungsten, tellurium, selenium, iron, nickel, cobalt, osmium, and oxides or hydroxides of these metals can be used as the vulcanizing agents. 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 two or more. The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass in total per 100 parts by mass of the rubber component in the rubber composition of the present embodiment.

Examples of the vulcanization accelerator include thiourea-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiuram-based vulcanization accelerators, and thiazole-based vulcanization accelerators. The vulcanization accelerator may be used in a single amount of 1 kind, or two or more kinds may be used in combination. The content of the vulcanization accelerator may be 0.2 to 5.0 parts by mass in total per 100 parts by mass of the rubber component in the rubber composition of the present embodiment, for example.

The filler and the reinforcing agent are added for adjusting the hardness of the rubber or improving the mechanical strength, and are not particularly limited, and examples thereof include carbon black, silica, clay, talc, and calcium carbonate. 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]And crystalline aluminosilicates containing hydrogen for correcting charge and alkali metals or alkaline earth metals, as in various zeolites. The filler and the reinforcing agent may be used alone in 1 kind, or two or more kinds may be used in combination. The amount of these fillers and reinforcing agents to be blended is not particularly limited, and may be adjusted depending on the physical properties required for the rubber composition and the crosslinked rubber or vulcanized rubber obtained from the rubber composition. The content of the filler and the reinforcing agent may be 15 to 200 parts by mass in total per 100 parts by mass of the rubber component in the rubber composition of the present embodiment, for example.

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), DOS (dioctyl sebacate), DOA (dioctyl adipate), ester plasticizers, ether ester plasticizers, thioether plasticizers, aromatic oils, naphthenic oils, lubricating oils, process oils, paraffins, liquid paraffins, vaseline, petroleum asphalt and other petroleum plasticizers. The plasticizer may be used in an amount of 1 or more, depending on the properties required for the rubber composition and the crosslinked rubber or vulcanized rubber obtained from the rubber composition. The content of the plasticizer may be 5 to 50 parts by mass in total relative to 100 parts by mass of the rubber component in the rubber composition of the present embodiment, for example.

When the rubber composition is kneaded or vulcanization molded, a processing aid or a lubricant may be added to the rubber composition in order to improve the processability and surface lubricity, for example, to facilitate separation from a roll, a molding die, or a screw of an extruder. Examples of the processing aid and the lubricant include fatty acids such as stearic acid, paraffin-based processing aids such as polyethylene, and fatty acid amides. The processing aid and the lubricant may be used alone in 1 kind or in combination of two or more kinds. The content of the processing aid and the lubricant may be 0.5 to 5 parts by mass in total relative to 100 parts by mass of the rubber component in the rubber composition of the present embodiment, for example.

As the antioxidant for improving heat resistance, a primary antioxidant for trapping radicals to prevent autoxidation, which is used in general rubber applications, and a secondary antioxidant for making hydrogen peroxide harmless can be added. The content of these antioxidants is 0.1 to 10 parts by mass, preferably 2 to 5 parts by mass, per 100 parts by mass of the rubber component in the rubber composition. These antioxidants may be used alone or in combination of two or more. Examples of the primary antioxidant include phenol antioxidants, amine antioxidants, acrylate antioxidants, imidazole antioxidants, metal carbamate salts, and waxes. Examples of the secondary antioxidant include a phosphorus antioxidant, a sulfur antioxidant, and an imidazole antioxidant. Specific 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-naphthylp-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, N-phenyl-, 4,4 ' -butylidenebis (3-methyl-6-t-butylphenol), 2-thiobis (4-methyl-6-t-butylphenol), 7-octadecyl-3- (4 ' -hydroxy-3 ', 5 ' -di-t-butylphenyl) propionate, tetrakis [ methylene-3- (3 ', 5 ' -di-t-butyl-4 ' -hydroxyphenyl) propionate ] methane, pentaerythrityl tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate ], 1, 6-hexanediol bis [3- (3, 5-di-t-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-thiodiethylene 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, tetrakis [ methylene (3, 5-di-tert-butyl-4-hydroxyhydrocinnamate) ] methane, N ' -dimethylenebis (3, 5-di-tert-butyl-4-hydroxy) hydrocinnamide, N ' -hexamethylene, Octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 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 monononylphenyl and dinonylphenyl) phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, diphenyl nonylphenyl phosphite, triphenyl phosphite, tris (tridecyl) phosphite, tris (tert-butyl-4-hydroxyphenyl) phosphite, tris (tert-butyl-5-methyl-phenyl) phosphite, tris (nonyl) phosphite, tris (ethyl-phenyl) 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 ' -ethylidenebis (4, 6-di-tert-butylphenol) fluorophosphite, 4 ' -isopropylidene-diphenylphenalkyl (C12-C15) phosphite, cycloneopentanetetraylbis (2, 4-di-tert-butylphenyl) phosphite, Cyclic neopentanetetraylbis (2, 6-di-t-butyl-4-phenyl phosphite), cyclic neopentanetetraylbis (nonylphenyl phosphite), bis (nonylphenyl) pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearyl pentaerythritol diphosphite, hydrogenated bisphenol a pentaerythritol phosphite polymer, and the like.

In order to improve the adhesion between the rubber component such as the copolymer and the filler and the reinforcing agent and to 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 two or more kinds may be used in combination. Examples of the silane coupling agent include, but are not particularly limited to, 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, silane coupling agent, and silane coupling agent, 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-benzothiazolylthio tetrasulfide, 3-trimethoxysilylpropyl methacryloylmonosulfide, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, isobutyltrimethoxysilane, N-decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, tolyltrimethoxysilane, and the like, Octadecylmethyldimethoxysilane, octadecyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, triphenylchlorosilane, heptadecafluorodecylmethyldichlorosilane, heptadecafluorodecyltrichlorosilane, triethylchlorosilane, etc.

The rubber composition of the present embodiment may additionally include at least 1 raw rubber (uncrosslinked or unvulcanized rubber) selected from the group consisting of natural rubber, isoprene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, butadiene rubber, styrene-butadiene rubber and ethylene-propylene rubber. The rubber composition of the present embodiment is preferably used in the form of a vulcanized rubber for practical use by vulcanization. The vulcanization can be carried out by a known method, generally using a thiourea-based vulcanizing agent, at a vulcanization temperature of 120 to 230 ℃.

The rubber composition of the present embodiment has a longer scorch time and a better moldability as a rubber than a rubber composition containing a copolymer obtained by a conventional radical polymerization method. Specifically, the scorch time t5 at 125 ℃ measured according to JIS K6300 for the rubber composition containing the copolymer of a chloroprene monomer and an unsaturated nitrile compound prepared under the sample preparation conditions (I) is 15 minutes or more.

The vulcanized molded article according to one embodiment of the present invention is produced by vulcanizing a rubber composition containing the copolymer. The vulcanized molded article of the present embodiment can simultaneously have the following features by using the copolymer: good molding processability and excellent oil resistance, high-temperature rubber physical properties (high-temperature compression set), low-temperature rubber physical properties (low-temperature compression set), and mechanical strength (breaking strength and elongation at break). The vulcanization temperature may be appropriately set depending on the composition, and is, for example, 130 to 230 ℃. The vulcanization time may be appropriately set depending on the composition and shape, and is, for example, 10 to 90 minutes. 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 the step of producing the vulcanized molded article of the present embodiment, secondary vulcanization may be performed at 150 to 200 ℃ as necessary. The compression set of the vulcanized molded article can be improved by the secondary vulcanization.

In the copolymer of a chloroprene monomer and an unsaturated nitrile compound used for the vulcanized molded article of the present embodiment, the content (bonding amount) of the unsaturated nitrile compound is preferably 1.0 to 18.0% by mass, and more preferably 5.0 to 14.0% by mass.

The vulcanized molded article of the present embodiment has better high-temperature rubber physical properties (i.e., lower high-temperature compression set) than vulcanized molded articles obtained using a composition containing a copolymer obtained by a conventional radical polymerization method. Specifically, the compression set at 130 ℃ for 72 hours measured according to JIS K6262 can be 20% or less when the vulcanized rubber produced under the above-mentioned sample production conditions (II) is evaluated.

The vulcanized molded product of the present embodiment is excellent in oil resistance. That is, the weight change rate Δ W of the vulcanized molded article of the present embodiment measured by using IRM903 oil in accordance with JIS K6258 can be set to less than 15%. The vulcanized molded product of the present embodiment is excellent in low-temperature rubber properties. That is, the compression set of the vulcanized molded article of the present embodiment after 72 hours at 0 ℃ as measured according to JIS K6262 can be 25% or less. The vulcanized molded article of the present embodiment is excellent in mechanical strength (breaking strength and elongation at break). That is, the vulcanized molded body of the present embodiment preferably has a breaking strength of 20MPa or more, and an elongation at break of more than 300%, as measured according to JIS K6251.

The vulcanization molded article of the present embodiment is particularly preferably a vulcanization molded article comprising a statistical copolymer of a chloroprene monomer and an unsaturated nitrile compound having a content (bonding amount) of the unsaturated nitrile compound of 5.0 to 14.0 mass%. The vulcanized molded article may have the above excellent high-temperature rubber properties, oil resistance and mechanical strength, and may have particularly excellent low-temperature rubber properties in which the compression set after 72 hours at 0 ℃ as measured according to JIS K6262 is 20% or less. Further, the vulcanized molded article can exhibit particularly excellent low-temperature rubber physical properties at-15 ℃ or lower in the Gieman torsion test (T10).

Generally, when the scorch time of the rubber composition is long, vulcanization is delayed, and therefore, the vulcanization density may be low. Further, generally, a vulcanized molded body having a low vulcanization density has a large compression set. Therefore, a vulcanized molded product produced using a rubber composition having a long scorch time and a delayed vulcanization tends to have a low vulcanization density and a large compression set. However, the vulcanized molded article of the present embodiment exhibits an excellent effect of reducing compression set at low temperatures and high temperatures, despite the use of a rubber composition having a long scorch time.

The above-mentioned vulcanized molded article can be suitably used for a power transmission belt, a conveyor belt, a hose, a wiper, a dipped article, a sealer, a gasket, an adhesive, a protective cover, a rubber cloth, a rubber roller, a vibration-proof rubber, a sponge article, a rubber liner and an air spring. The method for producing these products comprising the vulcanized molded article is not particularly limited as long as the vulcanized molded article is blended.

(Transmission belt and conveyer belt)

Specific examples of the transmission belt and the conveying belt include a flat belt, a conveying belt, a timing belt, a V-belt, a ribbed belt, and a circular belt. The vulcanized molded article of the present embodiment can improve the mechanical strength, oil resistance and bending fatigue resistance of a transmission belt and a conveyor belt. This makes it possible to manufacture a belt that can be used even when exposed to an environment of scattered oil, which has been difficult to achieve with conventional materials.

(Flexible pipe)

The hose is a bendable pipe, and specifically, there are high/low pressure hoses for water, oil, gas, steam, and oil pressure. The vulcanized molded article of the present embodiment can improve the mechanical strength, oil resistance and sagging 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 has been difficult to achieve with conventional materials.

(wiper)

The wiper is used for a windshield, a rear view glass, and the like of an automobile, an electric car, an airplane, a ship, a construction machine, and the like. The vulcanized molded article of the present embodiment can improve mechanical strength, oil resistance, endurance fatigue resistance, and permanent set resistance (low compression set) of a wiper. This makes it possible to manufacture a wiper that can be used even in an environment with a large amount of oil stains, which has been difficult to achieve with conventional materials.

(seals and gaskets)

The seal is a member for preventing leakage of liquid and gas, and intrusion of dust and foreign matter such as rainwater and dust into a machine or a device, and specifically, a gasket for fixing use and a gasket for a movable portion or a movable portion are used. As the gasket to which the seal part is fixed by a bolt or the like, various materials suitable for the purpose are used for a soft gasket such as an O-ring or a rubber sheet. The gasket is used for a shaft of a pump or an engine, a rotating portion such as 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 vulcanized molded article of the present embodiment can improve the mechanical strength and oil resistance of the seal. This makes it possible to manufacture a seal for a nonpolar fluid such as engine oil or gear oil, which has been difficult to realize with conventional materials. Further, the vulcanized molded article of the present embodiment has good sag resistance (low compression set) in addition to the above, and therefore, it is possible to obtain good sealing performance in which the shape of the sealing material is not easily changed even after long-term use.

(protective cover)

The boot is a member having a corrugated shape in which the outer diameter gradually increases from one end to the other end, and specifically 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. The vulcanized molded article of the present embodiment can improve the mechanical strength, oil resistance and fatigue resistance of the boot. Thus, a protective cover having excellent reliability with respect to a nonpolar liquid such as oil or grease contained therein can be manufactured as compared with conventional materials. Further, since the sagging resistance (low compression set) is also excellent, a caulked portion such as a metal strip for preventing leakage of oil contained therein is less likely to be deformed.

(rubber cloth)

The rubber cloth is a composite material of rubber and cloth fabric (fiber) obtained by bonding rubber to cloth, and is particularly widely used for clothing such as rubber boats, tent materials, raincoats, etc., waterproof sheets for buildings, cushioning materials, etc. The vulcanized molded article of the present embodiment can improve the mechanical strength and oil resistance of the blanket. This makes it possible to manufacture a blanket that can be used even in an environment where oil is scattered, which has been difficult to achieve with conventional materials.

(rubber roll)

The rubber roller is a roller manufactured by bonding and covering a metal core such as an iron core with rubber, and specifically, there are rubber rollers that meet required characteristics for various applications such as papermaking, various metal manufacturing, printing, general industrial use, agricultural equipment such as rice husking, food processing, and the like. The rubber roll is used in an environment where oil adheres when manufacturing industrial materials and products for iron making or paper making, and is exposed to acid or alkali when plating the products with gold, silver, nickel, chromium, zinc, or the like. The vulcanized molded article of the present embodiment can improve the mechanical strength, oil resistance and sagging resistance (low compression set) of the rubber roller. This makes it possible to manufacture a rubber roller used in an environment where oil adheres, which is difficult to realize with conventional materials.

(vibration-proof rubber)

The vibration-proof rubber is rubber for preventing transmission of vibration, and specifically, there are a torsional vibration damper, an engine mount, a muffler bracket, and the like for absorbing vibration during driving of an engine for an automobile or various vehicles to prevent noise. The vulcanized molded product of the present embodiment can improve the mechanical strength, oil resistance, and bending fatigue resistance of the vibration damping material. This makes it possible to manufacture a vibration damping rubber that can be used even in an environment where oil is scattered, which is difficult to achieve with conventional materials.

(sponge product)

The sponge is a porous substance having numerous pores opened therein, and specifically, there are vibration-proof materials, sponge seal members, diving suits, shoes, and the like. The vulcanized molded product of the present embodiment can improve the mechanical strength and oil resistance of the sponge product. This makes it possible to produce a sponge product that is not easily swollen, deformed, or discolored by oil, which has been difficult to achieve with conventional materials.

(rubber lining)

The rubber lining is a technique for preventing metal corrosion by bonding a rubber sheet to a metal surface of a pipe, a tank, or the like. In addition, rubber linings are also used in places where electrical resistance and abrasion resistance are required. The vulcanized molded article of the present embodiment can improve the oil resistance of the rubber lining. This can prevent corrosion of the piping and the tank due to oil, which has been difficult to achieve with conventional materials.

(air spring)

An air spring is a spring device using elasticity of compressed air, and is used for an air suspension of an automobile, a bus, a truck, or the like. The vulcanized molded article of the present embodiment can improve the mechanical strength, oil resistance, endurance fatigue resistance, and sagging resistance (low compression set) of the air spring. This makes it possible to manufacture an air spring that can be used even in an environment with a large amount of oil stains, which has been difficult to achieve with conventional materials.

Examples

The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to these examples.

< production of copolymer >

[ example 1]

To a polymerization reactor having an internal volume of 10 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.12 part by mass of benzylbutyl trithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 1.8 parts by mass of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 50%, 0.0065 parts by mass of phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer (dry up))

The chloroprene-acrylonitrile statistical copolymer latex obtained was adjusted to pH7.0, and frozen and coagulated on a metal plate cooled to-20 ℃ to thereby carry out emulsion breaking. The resulting sheet was washed with water and dried at 130 ℃ for 15 minutes, whereby a chloroprene-acrylonitrile statistical copolymer was obtained in a solid state.

(analysis conditions and analysis results of chloroprene-acrylonitrile statistical copolymer)

The polymerization rate of the chloroprene-acrylonitrile statistical copolymer was calculated from the dry weight (solid content concentration) by air-drying the chloroprene-acrylonitrile statistical copolymer latex. Specifically, the calculation is performed by the following equation. In the formula, the solid content concentration is a solid content concentration (mass%) obtained by heating 2g of the emulsion at 130 ℃ and removing volatile components from the weight change before and after heating. The total charge and the evaporation residue are calculated from the polymerization recipe. The evaporation residue represents: among the chemicals charged at the time of polymerization, the weight of the chemicals remaining as a solid component together with the copolymer without volatilization at 130 ℃.

Polymerization rate [% ] { (total charge amount [ g ] × solid content concentration [ mass% ]/100) - (evaporation residual amount [ g ]) }/monomer charge amount [ g ] × 100

The number average molecular weight Mn, weight average molecular weight Mw and molecular weight distribution (Mw/Mn) (in terms of standard polystyrene) of the copolymer were measured by using TOSOH HLC-8320GPC after the dry sample was sampled at an adjusted concentration of 0.1 mass% with THF. In this case, TSK Guard Colomn HHR-H was used as a pre-column, 3 HSK gel GMHHR-H was used as an analytical column, and the flow was measured by a differential refractometer under conditions of a sample pump pressure of 8.0 to 9.5MPa, a flow rate of 1ml/min, and 40 ℃. The flow-out time and the molecular weight were measured using calibration curves prepared by measuring 9 points in total of standard polystyrene samples having known molecular weights listed below.

Mw＝8.42×10⁶、1.09×10⁶、7.06×10⁵、4.27×10⁵、1.90×10⁵、9.64×10⁴、3.79×10⁴、1.74×10⁴、2.63×10³

The acrylonitrile bonding amount (content) in the copolymer was determined from the nitrogen content of the copolymer. The content of nitrogen atoms in the copolymer was determined by using a 100mg dry sample and an element analyzer (Sumigraph 220F: manufactured by Suxibo chemical analysis center). Regarding the temperature of the electric furnace, the temperature of the reaction furnace was set to 900 deg.C, the temperature of the reduction furnace was set to 600 deg.C, the temperature of the column was set to 70 deg.C, and the temperature of the detector was set to 100 deg.C, and oxygen gas was flowed at 0.2ml/min as a combustion gas, and helium gas was flowed at 80ml/min as a carrier gas. A standard curve was made by using aspartic acid (10.52%) with a known nitrogen content for the standard. As a result, the number average molecular weight (Mn) was 11.0X 10⁴g/mol, weight average molecular weight (Mw) 25.3X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.3. Further, the acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was 9.3 mass%.

(based on¹Analysis of functional groups derived from chain transfer agent by H-NMR measurement)

Analysis of the chain transfer agent-derived functional groups in the resulting chloroprene-acrylonitrile statistical copolymer was carried out as follows. The chloroprene-acrylonitrile statistical copolymer thus obtained was purified with benzene and methanol, and freeze-dried again to obtain a sample for measurement. 30mg of a chloroprene-acrylonitrile statistical copolymer was dissolved in 1ml of deuterated chloroform, and the solution was measured at 30 ℃ using ECX400(400MHz) manufactured by JEOL¹H-NMR. Preparation of statistical copolymer of chloroprene and acrylonitrile obtained in example 1¹The H-NMR spectrum is shown in FIG. 1. A peak (peak indicated by a in fig. 1) derived from the chain transfer agent (benzylbutyl trithiocarbonate) used was clearly observed. The structures of the identified functional groups are shown in table 1 below. The following examples and comparative examples are also the same.

[ example 2]

To a polymerization reactor having an internal volume of 10 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.11 part by mass of benzyl 1-pyrrolyldithiocarbamate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 1.8 parts by mass of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 50%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 14.0X 10⁴g/mol, weight average molecular weight (Mw) 33.6X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer, and was 8.9 mass%.

[ example 3]

To a polymerization reactor having an internal volume of 10 liters, 26 parts by mass of a chloroprene monomer, 36 parts by mass of an acrylonitrile monomer, 0.12 part by mass of benzylbutyl trithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 1.8g of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 50%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.8X 10⁴g/mol, weight average molecular weight (Mw) of 31.7X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.3. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer and was 13.0 mass%.

[ example 4]

To a polymerization reactor having an internal volume of 10 liters, 20 parts by mass of a chloroprene monomer, 47 parts by mass of an acrylonitrile monomer, 0.15 part by mass of benzylbutyl trithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 2.25 parts by mass of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 65%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.6X 10⁴g/mol, weight average molecular weight (Mw) 32.6X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer and was 16.0 mass%.

[ example 5]

To a polymerization reactor having an internal volume of 10 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.16 part by mass of benzylbutyl trithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 2.4 parts by mass of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 65%, phenothiazine as a polymerization terminator was added to stop the polymerization. And, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 10.9X 10⁴g/mol, weight average molecular weight (Mw) 26.2X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer, and was 10.0 mass%.

[ example 6]

To a polymerization reactor having an internal volume of 10 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.10 part by mass of benzylbutyl trithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 1.5 parts by mass of a 2% potassium persulfate aqueous solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 65%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.2X 10⁴g/mol, weight average molecular weight (Mw) of 31.7X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer, and was 9.6 mass%.

[ example 7]

To a polymerization reactor having an internal volume of 10 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.13 part by mass of dibenzyltrithiocarbonate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid-formaldehyde condensate (manufactured by Kao corporation) were added. 1.8 parts by mass of a 2% aqueous potassium persulfate solution was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the final polymerization rate reached 50%, 0.0065 parts by mass of phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.9X 10⁴g/mol, weight average molecular weight (Mw) 36.1X 10⁴g/mol, molecular weight distribution (Mw/Mn) 2.6. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer, and was 9.9 mass%.

Comparative example 1

(preparation of chloroprene-Acrylonitrile statistical copolymer latex)

To a polymerization reactor having an internal volume of 3 liters, 28 parts by mass of a chloroprene monomer, 28 parts by mass of an acrylonitrile monomer, 0.5 part by mass of diethyl dithioxanthogenate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid formaldehyde condensate (manufactured by Kao corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the polymerization rate reached 50%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.0X 10⁴g/mol、The weight average molecular weight (Mw) was 44.2X 10⁴g/mol, molecular weight distribution (Mw/Mn) 3.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer was determined by elemental analysis of nitrogen atoms in the polymer, and was 8.9 mass%.

Comparative example 2

(preparation of chloroprene-Acrylonitrile statistical copolymer latex)

To a polymerization reactor having an internal volume of 3 liters, 20 parts by mass of a chloroprene monomer, 47 parts by mass of an acrylonitrile monomer, 0.5 part by mass of diethyl dithioxanthogenate, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by HARIMA chemical Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of a sodium salt of a β -naphthalenesulfonic acid formaldehyde condensate (manufactured by Kao corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40 ℃ under a nitrogen gas flow. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the flow rates were adjusted by solenoid valves in accordance with the change in the heat amount of the refrigerant in 10 seconds from the start of polymerization, and then the flow rates were adjusted again every 10 seconds, thereby continuing the polymerization. When the polymerization rate reached 50%, phenothiazine as a polymerization terminator was added to stop the polymerization. Then, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile statistical copolymer latex.

(drying of chloroprene-Acrylonitrile statistical copolymer)

(analysis of chloroprene-Acrylonitrile statistical copolymer)

As a result of analysis by the foregoing method, the number average molecular weight (Mn) was 13.8X 10⁴g/mol, weight average molecular weight (Mw) 46.9X 10⁴g/mol, molecular weight distribution (Mw/Mn) 3.4. The acrylonitrile bonding amount in the chloroprene-acrylonitrile statistical copolymer is determined by carrying out element of nitrogen atom in the polymerThe content was determined by analysis to be 16.2% by mass.

< preparation of rubber composition >

100 parts by mass of the copolymer of examples 1 to 7 or comparative examples 1 and 2 was kneaded with 2 parts by mass of 4,4 '-bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine (NORAC CD manufactured by NORAC chemical Co., Ltd.) 4 parts by mass of magnesium oxide (Kyowamag #150 manufactured by Kyowa chemical Co., Ltd.), 50 parts by mass of CARBON black (SRF; ASAHI #50 manufactured by ASAHI CARBON Co., Ltd.), 5 parts by mass of a polyether ester plasticizer (Adekacizer RS-735 manufactured by ADEKA Co., Ltd.), 5 parts by mass of zinc oxide (manufactured by Sakai chemical Co., Ltd.), 1.5 parts by mass of ethylenethiourea (Accel 22S manufactured by Chuan chemical Co., Ltd.), and 1 part by mass of N-phenyl-N' - (1, 3-dimethylbutyl) p-phenylenediamine (RAC 6C manufactured by NORAC chemical industry Co., Ltd.) for 20 minutes using an 8-inch roll having a cooling water temperature set to 40 ℃, a rubber composition was obtained.

< measurement of scorch time of rubber composition >

The rubber composition obtained by the above method was subjected to Mooney scorch test at 125 ℃ in accordance with JIS K6300, and the scorch time t5 was measured. The scorch time t5 refers to: the scorch time was measured as the time (minutes) taken for the viscosity of the rubber composition to increase from the minimum viscosity to 5%.

< preparation of vulcanized rubber >

The rubber composition was heat-treated at 170 ℃ for 20 minutes and then at 170 ℃ for 2 hours in heated air by using electrothermal pressure in accordance with JIS K6250, to prepare a vulcanized rubber.

< measurement of mechanical Strength of vulcanized rubber >

The mechanical strength (breaking strength and elongation at break) of the vulcanized rubbers using the copolymers of examples 1 to 7 or comparative examples 1 and 2 was measured in accordance with JIS K6251. The product is judged to be qualified when the breaking strength is more than or equal to 20MPa and the breaking elongation is more than 300 percent.

< hardness of vulcanized rubber >

The hardness of the vulcanized rubber using the copolymers of examples 1 to 7 or comparative examples 1 and 2 was measured in accordance with JIS K6253.

< measurement of oil resistance of vulcanized rubber >

The oil resistance of the vulcanized rubbers using the copolymers of examples 1 to 7 or comparative examples 1 and 2 was measured in accordance with JIS K6258. The oil type was IRM903 oil, and the oil resistance was evaluated from the volume change rate (Δ V) and weight change rate (Δ W) after immersion at 135 ℃ for 72 hours. And judging that the delta V is less than 20% and the delta W is less than 15% as qualified.

< implementation of Gieman torsion test (T10) on vulcanized rubber >

The Gieman torsion test (T10) for vulcanized rubbers using the copolymers of examples 1 to 7 and comparative examples 1 and 2 was carried out in accordance with JIS K6261. T10 is a temperature at which the torsional modulus is 10 times higher than that at normal temperature (23 ℃), and a lower number indicates better cold resistance. The sample was qualified at 0 ℃ or lower, excellent at-10 ℃ or lower, and extremely excellent at-15 ℃ or lower.

< measurement of Low-temperature compression set of vulcanized rubber >

The low-temperature compression set of the vulcanized rubbers using the copolymers of examples 1 to 7 or comparative examples 1 and 2 was measured at 0 ℃ for 72 hours in accordance with JIS K6262. The steel sheet is acceptable when the Compression Set (CS) is 25% or less, and excellent when the CS is 20% or less.

< measurement of high-temperature compression set of vulcanized rubber >

The high temperature compression set of the vulcanized rubbers using the copolymers of examples 1 to 7 or comparative examples 1 and 2 was measured at 130 ℃ for 72 hours in accordance with JIS K6262. The steel sheet is acceptable when the Compression Set (CS) is 22% or less, and excellent when the CS is 20% or less.

The results of examples 1 to 7 and comparative examples 1 and 2 are shown in table 1 below.

[ Table 1]

The rubber compositions of examples 1 to 7 had a long scorch time and good moldability as rubbers. The vulcanized rubbers of examples 1 to 7 were excellent in mechanical strength (breaking strength and elongation at break) and oil resistance, and had good rubber physical properties (compression set) at low temperatures and high temperatures.

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Copolymer of chloroprene monomer and unsaturated nitrile compound, composition comprising copolymer, vulcanized molded article of composition, and use of vulcanized molded article

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