WO2023153405A1 - Rubber composition, vulcanizate, and vulcanized molded body - Google Patents

Abstract

Provided is a rubber composition with which it is possible to obtain a vulcanizate and a vulcanized molded body that is exceptional in terms of both elongation at break and compression permanent set after heating. According to the present invention, there is provided a rubber composition containing 100 parts by mass of chloroprene rubber, 2-100 parts by mass of silica having a BET specific surface area of 10-120 m2/g, 0.1-8 parts by mass of a maleimide compound, 0.1-5 parts by mass of an organic peroxide, and 1-15 parts by mass of a silane coupling agent per 100 parts by mass of the silica.

Description

Rubber composition, vulcanizate, and vulcanized molding

TECHNICAL FIELD The present invention relates to rubber compositions, vulcanizates, and vulcanized moldings.

Chloroprene rubber has excellent mechanical strength, weather resistance, chemical resistance, heat resistance, cold resistance, and oil resistance. , wipers, dipping products, sealing parts, adhesives, boots, rubberized fabrics, rubber rolls and other materials.

For example, in Patent Document 1, 100 parts by mass of a chloroprene rubber, 20 to 80 parts by mass of a silica filler, 0.5 to 4 parts by mass of a maleimide compound, and 0.1 to 3 parts by mass of an organic peroxide. A rubber composition having

JP 2021-95493 A

However, conventional chloroprene-based rubber compositions have room for improvement in heat resistance and compression set in vulcanized moldings of rubber compositions containing the chloroprene-based rubber. It has been difficult to obtain a rubber composition from which a vulcanized product and a vulcanized molded product can be obtained which are excellent in both compression set and compression set.

The present invention has been made in view of such circumstances, and provides a rubber composition that can obtain a vulcanized product and a vulcanized molded product that are excellent in both elongation at break and compression set after heating. It is.

According to the present invention, 100 parts by mass of a chloroprene rubber, 2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g, 0.1 to 8 parts by mass of a maleimide compound, and 0 parts by mass of an organic peroxide. and 1 to 15 parts by weight of a silane coupling agent per 100 parts by weight of said silica.

As a result of extensive studies, the present inventors found that the rubber composition contains 100 parts by mass of chloroprene rubber, 2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g, and 0.1 maleimide compound. ~ 8 parts by mass, 0.1 to 5 parts by mass of an organic peroxide, and 1 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of the silica, elongation at break and compression after heating The present inventors have found that it is possible to obtain a rubber composition from which a vulcanized product and a vulcanized molding excellent in both permanent set can be obtained, and have completed the present invention.

According to another aspect of the present invention, there is provided a vulcanizate of the rubber composition described above.
Moreover, according to another aspect of the present invention, there is provided a vulcanized molding of the rubber composition described above.
Various embodiments of the present invention are illustrated below. The embodiments shown below can be combined with each other.

[1] 100 parts by mass of chloroprene-based rubber, 2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g, 0.1 to 8 parts by mass of a maleimide compound, and 0.1 to 0.1 part of an organic peroxide A rubber composition comprising 5 parts by mass and 1 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of the silica.
[2] The chloroprene rubber is a homopolymer of 2-chloro-1,3-butadiene, or at least one monomer selected from 2,3-dichloro-1,3-butadiene and unsaturated nitrile monomers. The rubber composition according to [1], which contains a copolymer of a monomer and 2-chloro-1,3-butadiene.
[3] The silane coupling agent is at least selected from a silane coupling agent having a double bond in its structure, a silane coupling agent having an amino group, and a silane coupling agent having a double bond and an amino group The rubber composition according to [1] or [2], comprising one.
[4] The silane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth) At least one silane coupling agent selected from acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane [1] to [ 3]. The rubber composition according to any one of the above items.
[5] The rubber composition according to any one of [1] to [4], further containing 0.1 to 20 parts by mass of a hydrotalcite compound with respect to 100 parts by mass of the chloroprene rubber.
[6] The maleimide compound is N,N'-o-phenylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-(4,4' -diphenylmethane)bismaleimide, 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 4-methyl-1,3- The rubber composition according to any one of [1] to [5], which is at least one maleimide compound selected from phenylene bismaleimide and 1,6'-bismaleimide-(2,2,4-trimethyl)hexane. .
[7] The organic peroxide is dicumyl peroxide, 1,4-bis[(t-butylperoxy)isopropyl]benzene, tert-butyl α-cumyl peroxide, 2,5-dimethyl-2,5-bis selected from (t-butylperoxy)hexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne and butyl 4,4-bis[(t-butyl)peroxy]pentanoate The rubber composition according to any one of [1] to [6], which is at least one organic peroxide.
[8] The rubber composition according to any one of [1] to [7], which further contains 1 to 30 parts by mass of a compound having a thioether structure with respect to 100 parts by mass of the chloroprene rubber.
[9] A vulcanizate of the rubber composition according to any one of [1] to [8].
[10] A vulcanized molded article of the rubber composition according to any one of [1] to [8].

According to the rubber composition of the present invention, it is possible to obtain a rubber composition from which a vulcanizate and a vulcanized molded article which are excellent in both elongation at break and compression set after heating can be obtained. Furthermore, the obtained vulcanizates and vulcanized moldings can be used as various members that require excellent heat resistance and/or excellent compression set by taking advantage of their properties, especially sealing materials. , gaskets, packings, and the like.

Hereinafter, the present invention will be described in detail by exemplifying embodiments of the present invention. The present invention is not limited in any way by these descriptions. Each feature of the embodiments of the invention described below can be combined with each other. In addition, the invention is established independently for each characteristic item.

1. Rubber Composition The rubber composition according to the present invention comprises 100 parts by mass of a chloroprene rubber, 2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g, and 0.1 to 8 parts by mass of a maleimide compound. , 0.1 to 5 parts by weight of an organic peroxide, and 1 to 15 parts by weight of a silane coupling agent per 100 parts by weight of the silica. Moreover, the rubber composition according to the present invention is a rubber composition from which a vulcanizate and a vulcanized molded article which are excellent in both elongation at break and compression set after heating can be obtained.

1.1 Chloroprene-based rubber The chloroprene-based rubber according to the present invention is a rubber containing a chloroprene-based polymer having chloroprene (2-chloro-1,3-butadiene) as a monomer unit (monomer unit = structural unit). indicates Examples of the chloroprene-based polymer include chloroprene homopolymers and chloroprene copolymers (copolymers of chloroprene and a monomer that can be copolymerized with chloroprene). The polymer structure of the chloroprene-based polymer is not particularly limited.

Incidentally, commercially available 2-chloro-1,3-butadiene may contain a small amount of 1-chloro-1,3-butadiene as an impurity. 2-Chloro-1,3-butadiene containing such a small amount of 1-chloro-1,3-butadiene can also be used as the chloroprene monomer in the present embodiment.

A chloroprene-based rubber according to one embodiment of the present invention is a homopolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene), or a monopolymer of 2,3-dichloro-1,3-butadiene and an unsaturated nitrile. A copolymer of at least one monomer selected from monomers and 2-chloro-1,3-butadiene can be included. A chloroprene-based rubber according to one embodiment of the present invention comprises a chloroprene homopolymer and at least one monomer selected from 2,3-dichloro-1,3-butadiene and unsaturated nitrile monomers. It may consist of a rubber containing a copolymer with chloroprene, or it may consist of a rubber containing a homopolymer of chloroprene, 2,3-dichloro-1,3-butadiene and an unsaturated nitrile. It can also be made of a rubber containing a copolymer of at least one monomer selected from monomers and chloroprene.

A chloroprene-based rubber according to one embodiment of the present invention contains a copolymer containing a monomer unit derived from a 2,3-dichloro-1,3-butadiene monomer unit and an unsaturated nitrile monomer. can be done. The chloroprene-based rubber according to one embodiment of the present invention has a total content of 2,3-dichloro-1,3-butadiene monomer units and unsaturated nitrile monomer units when the rubber is 100% by mass. can be less than 25% by mass, preferably 1% by mass or more and less than 25% by mass.
The contents of 2,3-dichloro-1,3-butadiene monomer units and unsaturated nitrile monomer units in the chloroprene-based rubber according to one embodiment of the present invention are, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 mass%, less than 25 mass% , within a range between any two of the numerical values exemplified herein.

The chloroprene-based rubber according to one embodiment of the present invention preferably contains a copolymer containing monomer units derived from unsaturated nitrile monomers. The content of unsaturated nitrile monomer units in the chloroprene-based rubber according to one embodiment of the present invention is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24% by mass, less than 25% by mass and within a range between any two of the numerical values exemplified here There may be. By setting the unsaturated nitrile monomer unit content to less than 25% by mass, the obtained rubber composition has sufficient cold resistance. In particular, by setting the content of the unsaturated nitrile monomer unit to 1% by mass or more, the obtained rubber composition has sufficient oil resistance, and the tensile strength and cold resistance are well balanced. It is possible to obtain a vulcanized molded article excellent in

Unsaturated nitriles include acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and the like. An unsaturated nitrile can be used individually by 1 type or in combination of 2 or more types. The unsaturated nitrile may contain acrylonitrile from the viewpoint of easily obtaining excellent moldability, and from the viewpoint of easily obtaining excellent breaking strength, breaking elongation, hardness, tear strength, and oil resistance in the vulcanized molded product. preferable.

The content of unsaturated nitrile monomer units contained in the chloroprene-based rubber can be calculated from the content of nitrogen atoms in the chloroprene-based rubber. Specifically, the content of nitrogen atoms in 100 mg of chloroprene-based rubber is measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Service, Ltd.), and the content of structural units derived from unsaturated nitrile monomers You can calculate the amount. Elemental analysis can be measured under the following conditions. For example, the electric furnace temperature is set to 900° C. for the reactor, 600° C. for the reduction furnace, the column temperature is 70° C., and the detector temperature is 100° C., oxygen as the combustion gas is 0.2 mL/min, and helium is 80 mL/min as the carrier gas. to flow. A calibration curve can be constructed using aspartic acid (10.52%) with a known nitrogen content as a standard.

The chloroprene-based rubber according to one embodiment of the present invention preferably contains 60 to 100% by mass of chloroprene monomer units when the chloroprene-based rubber is taken as 100% by mass. The content of chloroprene monomer units in the rubber is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 99, 100% by mass, and any two of the numerical values exemplified here may be within the range. By setting the content of the chloroprene monomer unit within the above numerical range, it is possible to obtain a rubber composition that can give a molded article having an excellent balance of hardness, tensile strength, and cold resistance.

A chloroprene-based rubber according to one embodiment of the present invention shall have monomer units other than a chloroprene monomer, a 2,3-dichloro-1,3-butadiene monomer and an unsaturated nitrile monomer. can also Monomer units other than chloroprene monomer, 2,3-dichloro-1,3-butadiene monomer and unsaturated nitrile monomer include chloroprene monomer, 2,3-dichloro-1,3- Although there is no particular limitation as long as it can be copolymerized with butadiene monomers and unsaturated nitrile monomers, esters of (meth) acrylic acid (methyl (meth) acrylate, butyl (meth) acrylate, (meth) ) 2-ethylhexyl acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 1-chloro-1 , 3-butadiene, butadiene, isoprene, ethylene, styrene, sulfur and the like.

The chloroprene-based rubber according to one embodiment of the present invention can contain 0 to 20% by mass of monomer units other than the chloroprene monomer and the unsaturated nitrile monomer when the rubber is 100% by mass. . The content of monomer units other than the chloroprene monomer and the unsaturated nitrile monomer in the rubber is, for example, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20% by mass. Yes, and may be in a range between any two of the values exemplified here. By adjusting the copolymerization amount of the monomer other than the chloroprene monomer and the unsaturated nitrile monomer to this range, these monomers were copolymerized without impairing the properties of the resulting rubber composition. The effect of this can be expressed.
In addition, the chloroprene-based rubber according to one embodiment of the present invention may consist of only chloroprene monomer units and unsaturated nitrile monomer units, and may consist of only chloroprene monomer units. can also

The rubber composition according to the present invention can use chloroprene-based rubbers singly or in combination of two or more.
When the rubber composition according to one embodiment of the present invention contains two or more chloroprene-based rubbers, unsaturated nitrile monomer units contained in the two or more chloroprene-based rubbers contained in the rubber composition and 2, The total content of 3-dichloro-1,3-butadiene is preferably less than 25% by weight.

The chloroprene-based polymer (chloroprene homopolymer, chloroprene copolymer, etc.) contained in the chloroprene-based rubber according to the present invention includes sulfur-modified chloroprene polymer, mercaptan-modified chloroprene polymer, xanthogen-modified chloroprene polymer, dithiocarbohydrate It may be a nato-based chloroprene polymer, a trithiocarbonate-based chloroprene polymer, a carbamate-based chloroprene polymer, or the like.

1.2 Method for producing chloroprene-based rubber The method for producing the chloroprene-based rubber according to the present invention is not particularly limited. can.
In the emulsion polymerization step according to one embodiment of the present invention, a chloroprene monomer, optionally a monomer containing 2,3-dichloro-1,3-butadiene and an unsaturated nitrile monomer, is added as an emulsifier or A latex containing a chloroprene-based polymer containing chloroprene monomer units by emulsification polymerization using an appropriate dispersant, catalyst, chain transfer agent, etc., and adding a polymerization terminator when the desired final conversion is reached. can be obtained.
Next, unreacted monomers can be removed from the polymerization liquid obtained by the emulsion polymerization step. The method is not particularly limited, and includes, for example, a steam stripping method.
Thereafter, the pH is adjusted, and the chloroprene-based rubber containing the chloroprene-based polymer can be obtained through conventional steps such as freezing and coagulation, washing with water, and drying with hot air.

The polymerization initiator used for emulsion polymerization is not particularly limited, and known polymerization initiators generally used for emulsion polymerization of chloroprene can be used. Examples of polymerization initiators include potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and organic peroxides such as t-butyl hydroperoxide.

The emulsifier used for emulsion polymerization is not particularly limited, and known emulsifiers generally used for emulsion polymerization of chloroprene can be used. Examples of emulsifiers include alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, alkali metal salts of rosin acid or disproportionated rosin acid (eg, potassium rosinate), and formalin condensates of β-naphthalenesulfonic acid. and alkali metal salts (for example, sodium salts) of.

The molecular weight modifier used for emulsion polymerization is not particularly limited, and known molecular weight modifiers generally used for emulsion polymerization of chloroprene can be used. compounds, trithiocarbonate-based compounds and carbamate-based compounds. Xanthogen-based compounds, dithiocarbonate-based compounds, trithiocarbonate-based compounds and carbamate-based compounds can be suitably used as the molecular weight modifier for the chloroprene-based rubber according to one embodiment of the present invention.

Although the polymerization temperature and the final conversion rate of the monomers are not particularly limited, the polymerization temperature may be, for example, 0 to 50°C or 10 to 50°C. The polymerization may be carried out so that the final conversion of monomer is in the range of 40-95% by weight. In order to adjust the final conversion, the polymerization may be terminated by adding a polymerization terminator for terminating the polymerization reaction when the desired conversion is achieved.

The polymerization terminator is not particularly limited, and known polymerization terminator generally used for emulsion polymerization of chloroprene can be used. Examples of the polymerization terminator include phenothiazine (thiodiphenylamine), 4-t-butylcatechol, 2,2-methylenebis-4-methyl-6-t-butylphenol and the like.

The chloroprene-based rubber according to one embodiment of the present invention can be prepared, for example, by removing unreacted monomers by a steam stripping method, adjusting the pH of the latex, freezing and coagulating by a conventional method, washing with water, drying with hot air, etc. can be obtained through the process of

Chloroprene-based rubbers are classified into mercaptan-modified type, xanthogen-modified type, sulfur-modified type, dithiocarbonate-based type, trithiocarbonate-based type and carbamate-based type according to the type of molecular weight modifier.

1.3 Silica The rubber composition according to the present invention contains 2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g with respect to 100 parts by mass of chloroprene rubber. Silica is commonly added to rubber compositions as a filler. Silica forms a covalent bond with a chloroprene-based polymer through a surface functional group (e.g., OH group) present on the surface of silica and a silane coupling agent. It is thought that the system polymer is strongly restrained, the elasticity is improved, and the compression set is improved.

Although not particularly limited, as silica, for example, a wet silica filler (silicic acid hydrate), a dry silica filler (anhydrous silicic acid), and a colloidal silica filler can be used, and a wet silica filler is preferable. As silica, surface unmodified silica can be used. As silica, surface-modified silica can also be used.

The silica contained in the rubber composition according to the present invention has a BET specific surface area of 10 to 120 m ² /g. The BET specific surface area is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120 m ² /g, and within the range between any two of the numerical values exemplified here may be By setting the BET specific surface area of silica to a specific range, the rubber composition according to the present invention can obtain a vulcanized product and a vulcanized molding that are excellent in both elongation at break and compression set after heating. It becomes a rubber composition. By setting the BET specific surface area of silica to the above upper limit or less, the number per unit mass of surface functional groups present on the surface of silica is defined, and specific surface functional groups (e.g., OH groups) present on the surface of silica It is presumed that the increase in reactivity with the chloroprene-based rubber, the decrease in compatibility between silica and the chloroprene-based rubber, and the aggregation of silica particles caused by heating are suppressed. In addition, by setting the BET specific surface area of silica to the above upper limit or less, the amount of surface functional groups per silica particle increases, the number of reaction points with the silane coupling agent possessed by one particle of silica increases, and the vicinity of silica increases. It is thought that the chloroprene-based polymer can be strongly restrained and the compression set is improved. Further, by making the BET specific surface area of silica equal to or higher than the above lower limit, the processability of the rubber composition can be maintained.

The specific surface area of silica can be measured by a vapor-phase adsorption method using nitrogen gas as the adsorption gas using, for example, a rapid surface area measuring device SA-1000 manufactured by Shibata Kagaku Kikai Kogyo Co., Ltd.

The rubber composition according to the present invention contains 2 to 80 parts by mass of silica with respect to 100 parts by mass of chloroprene rubber. The content of silica is, for example, 95 and 100 parts by mass, and may be within a range between any two of the numerical values exemplified here. By setting the amount of silica to be added to the above upper limit or more, the reinforcing effect and wear resistance can be maintained. In addition, by setting the amount of silica to be added to the above upper limit or less, aggregation and scorch are suppressed, and vulcanization proceeds sufficiently.

Silica can be used individually by 1 type or in combination of 2 or more types. When the rubber composition according to the present invention contains two or more types of silica, the specific surface area in a state in which multiple types of silica contained in the rubber composition of the present invention are mixed satisfies the above numerical range.

1.4 Silane Coupling Agent The rubber composition according to the present invention contains 1 to 15 parts by mass of a silane coupling agent per 100 parts by mass of silica. A silane coupling agent is added to improve the dispersibility of silica in rubber and the reinforcing effect between rubber and silica.

The silane coupling agent is not particularly limited, and those used in commercially available rubber compositions can be used. Examples include vinyl coupling agents, epoxy coupling agents, styryl coupling agents, methacrylic coupling agents. Ring agents, acrylic coupling agents, amino coupling agents, polysulfide coupling agents, and mercapto coupling agents can be mentioned.
A silane coupling agent according to one embodiment of the present invention includes a silane coupling agent having a double bond in the structure, a silane coupling agent having an amino group, and a silane coupling agent having a double bond and an amino group. It is preferable to include at least one selected.
A silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

The silane coupling agent having a double bond in its structure is not particularly limited except that it has a double bond in its structure. Examples include vinyl coupling agents, styryl coupling agents, and methacrylic coupling agents. , and acrylic coupling agents. In particular, vinyl coupling agents, methacrylic coupling agents, and acrylic coupling agents are preferable from the viewpoint of processability and reinforcing effect. A silane coupling agent having a double bond in its structure preferably has a (meth)acrylic group in its structure, and even more preferably has a methacrylic group.
Examples of the silane coupling agent having a double bond in its structure include vinyltrimethoxysilane, vinyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyl Mention may be made of trimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyltriethoxysilane, vinyltriacetoxysilane, allyltrimethoxysilane.

The silane coupling agent having an amino group is not particularly limited as long as it has an amino group in its structure, and those used in commercially available rubber compositions can be used. A silane coupling agent having an amino group can be an amino-based coupling agent. The silane coupling agent having an amino group can be a silane coupling agent having a primary amino group and/or a secondary amino group, and is more preferably a silane coupling agent having a secondary amino group. Silane coupling agents having an amino group include N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3 -aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. .

The rubber composition according to one embodiment of the present invention can also contain a silane coupling agent that has neither double bonds nor amino groups in its structure. The content of silane coupling agents having neither double bonds nor amino groups in their structures includes silane coupling agents having double bonds in their structures, silane coupling agents having amino groups in their structures, and double bonds and amino groups. It is preferably less than the total content of silane coupling groups. The rubber composition according to one embodiment of the present invention includes a silane coupling agent having a double bond in the structure and an amino group, when the total amount of silane coupling agents contained in the rubber composition is 100% by mass. and the silane coupling agent having a double bond and an amino group. It is even more preferred to have A rubber composition according to an embodiment of the present invention may not contain a silane coupling agent having neither double bonds nor amino groups in its structure.

The rubber composition according to the present invention contains 1 to 15 silane coupling agents per 100 parts by mass of silica. The content of the silane coupling agent can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, where It may be in a range between any two of the numerical values given. By using the silane coupling agent within this range, necessary and sufficient effects can be obtained and the occurrence of scorch can be suppressed.

5. Maleimide Compound The chloroprene-based rubber composition according to one embodiment of the present invention contains 0.1 to 8 parts by mass of a maleimide compound with respect to 100 parts by mass of the chloroprene-based rubber. A maleimide compound can be used individually by 1 type or in combination of 2 or more types.

The maleimide compound can contribute to vulcanization of the rubber composition as a co-crosslinking agent. Examples of maleimide compounds include N,N'-o-phenylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-(4,4' -diphenylmethane) bismaleimide, 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, bisphenol A diphenyl ether bismaleimide, 3, 3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl) Hexane can be mentioned. N,N'-m-phenylenebismaleimide (also known as m-phenylenedimaleimide) is particularly preferably used from the viewpoint of improving the heat resistance and compression set resistance of the resulting vulcanized molded product.

A rubber composition according to one embodiment of the present invention contains 0.1 to 8 parts by mass of a maleimide compound with respect to 100 parts by mass of a chloroprene rubber. The content of the maleimide compound is, for example, 0.1, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8 parts by mass, and the numerical values exemplified here may be in the range between any two of By making the content of the maleimide compound equal to or higher than the above lower limit, the vulcanization of the obtained rubber composition proceeds more sufficiently, and a vulcanized molded article having good compression set resistance and elongation at break after heating is obtained. be able to. Moreover, by making the content of the maleimide compound equal to or less than the above upper limit, the rubber elasticity of the obtained vulcanized molded product can be sufficiently maintained, and deterioration of resistance to compression set can be suppressed.

1.6 Organic Peroxide The rubber composition according to the present invention contains 0.1 to 5 parts by mass of an organic peroxide.
Organic peroxides can be used as vulcanizing agents. An organic peroxide can be used individually by 1 type or in combination of 2 or more types.

Examples of organic peroxides include dicumyl peroxide, benzoyl peroxide, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, diisobutyryl peroxide, and cumylperoxy neodeca. noate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4 -t-butyl cyclohexyl)peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxyneohepta noate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, t-butylperoxy-2-ethylhexanoate, di(3-methylbenzoyl) peroxide, benzoyl(3-methylbenzoyl) peroxide, dibenzoyl peroxide, 1, 1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy) cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropyl monocarbonate, t-butyl peroxy maleic acid, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxy laurate, t-butyl peroxy isopropyl monocarbonate, t-butyl peroxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-di-methyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, 2,2-di-(t-butylperoxy) Butane, t-butylperoxybenzoate, n-butyl 4,4-di-(t-butylperoxy)valerate, 1,4-bis[(t-butylperoxy)isopropyl]benzene, di-t-hexylper oxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl- 2,5-bis(t-butylperoxy)hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 4, butyl 4-bis[(t-butyl)peroxy]pentanoate, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne and the like. Among these, dicumyl peroxide, 1,4-bis[(t-butylperoxy)isopropyl]benzene, tert-butyl α-cumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy ) be at least one selected from hexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, and butyl 4,4-bis[(t-butyl)peroxy]pentanoate is preferred, and 1,4-bis[(t-butylperoxy)isopropyl]benzene is particularly preferred.

The rubber composition according to the present invention can contain 0.1 to 5 parts by mass of an organic peroxide with respect to 100 parts by mass of the chloroprene rubber. The amount of organic peroxide added is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2 , 3, 4, 5 parts by weight, and may be within a range between any two of the values exemplified herein. By setting the content of the organic peroxide within the above numerical range, processing safety is ensured and a good vulcanizate can be obtained.

1.7 Hydrotalcite Compound The rubber composition according to the present invention may contain 0.1 to 20 parts by mass of a hydrotalcite compound per 100 parts by mass of the chloroprene rubber. A hydrotalcite compound can function as an acid acceptor.
As the hydrotalcite compound, those represented by the following formula can be used.
[M ²⁺ _1−x M ³⁺ _x (OH) ₂ ] ^x+ [A _n−x/n ·mH ₂ O] ^x−

In the above formula,
M ²⁺ : at least one divalent metal ion selected from Mg ²⁺ , Zn ²⁺ etc. M ³⁺ : at least one trivalent metal ion selected from Al ³⁺ , Fe ³⁺ etc. A ⁿ⁻ : CO ₃ ²⁻ , Cl ⁻ , At least one n-type anion selected from NO ₃ ^2- , etc. X: 0<X≦0.33.

Examples of hydrotalcite _{compounds include Mg4.3Al2 (} OH) _{12.6CO3.3.5H2O , Mg3ZnAl2 (} OH _{) 12CO3.3H2O} , _{Mg4.5Al2 (} OH _{) 13CO3.3.5H2O , Mg4.5Al2} ( _{OH ) 13CO3 , Mg4Al2} (OH _{) 12CO3.3.5H2O} , _{Mg6Al2 (} OH _{) 16 CO3.4H2O , Mg5Al2 ( OH ) 14CO3.4H2O , Mg3Al2 ( OH} ) _10CO3.1.7H2O , _{Mg0.7Al0.3O 1 . 15} , and particularly preferably _{Mg4.3Al2 ( OH ) 12.6CO3.3.5H2O , Mg3ZnAl2 ( OH} ) _12CO3.3H2O , _Mg0.7 Al _0.3 O _1.15 .

When a hydrotalcite compound is used, the amount of the hydrotalcite compound added can be 0.1 to 20 parts by mass with respect to 100 parts by mass of the chloroprene rubber. The amount of the hydrotalcite compound added is, for example, 0.1, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 , 13, 14, 15, 16, 17, 18, 19, 20 parts by weight, and may be within a range between any two of the numerical values exemplified herein. A hydrotalcite compound can be used individually by 1 type or in combination of 2 or more types.

1.8 Compound Having Thioether Structure The chloroprene-based rubber composition according to one embodiment of the present invention can contain 1 to 30 parts by mass of a compound having a thioether structure with respect to 100 parts by mass of the chloroprene-based rubber. By using a compound having a thioether structure together with an organic peroxide, the vulcanization can be sufficiently progressed within the specified vulcanization time, and a vulcanizate with excellent compression set resistance and heat resistance can be obtained. In addition, the organic peroxide remaining after crosslinking and the hydroperoxide generated by thermal deterioration are decomposed, and the heat resistance of the obtained vulcanized molding is further improved.

A compound having a thioether structure according to one embodiment of the present invention can be represented, for example, by the following formula (1), or can have a structural unit represented by formula (2). Here, R ¹ , R ² , R ³ and R ⁴ can be any organic group which may have a substituent.

When the compound having a thioether structure according to one embodiment of the present invention is represented by formula (1), at least one of R ¹ and R ² preferably contains an ether structure. When the compound having one or more thioether structures according to one embodiment of the present invention contains a structural unit represented by formula (2), at least one of R ³ and R ⁴ preferably contains an ether structure. Moreover, in Formula (2), n is an arbitrary natural number of 1 or more. Moreover, the compound having one or more thioether structures according to one embodiment of the present invention preferably has two or more ether structures.

Also, in one aspect, R ¹ , R ² , R ³ and R ⁴ preferably have an alkylene group with 2 to 20 carbon atoms, more preferably an alkylene group with 2 to 11 carbon atoms. In one aspect, R ¹ , R ² , R ³ and R ⁴ may have a carbonyl group.

The amount of the compound having a thioether structure added can be 1 to 30 parts by mass with respect to 100 parts by mass of the chloroprene rubber. The added amount of the compound having a thioether structure is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30 parts by mass. and may be in the range between any two of the numerical values exemplified here. By setting the amount of the compound having a thioether structure to be at least the above lower limit, the organic peroxide remaining after cross-linking and the hydroperoxide generated by thermal deterioration are decomposed when the organic peroxide is added, and the heat resistance is improved. Excellent vulcanizates can be obtained. In addition, by setting the amount of the compound having a thioether structure to be the above upper limit or less, the vulcanization proceeds sufficiently, and the vulcanized molded article having sufficient moldability, compression set resistance, and heat resistance is obtained. It becomes a rubber composition.

1.9 Vulcanizing Agent The rubber composition according to one embodiment of the present invention may contain a vulcanizing agent in addition to the above compounds. A metal oxide can be mentioned as a vulcanizing agent. Examples of metal oxides include zinc oxide, magnesium oxide, lead oxide, trilead tetroxide, iron trioxide, titanium dioxide, and calcium oxide. The metal oxide preferably includes at least one of zinc oxide and magnesium oxide, may include zinc oxide and magnesium oxide, and preferably includes at least zinc oxide.

The rubber composition according to the present invention can contain 0.1 to 15 parts by mass of the vulcanizing agent per 100 parts by mass of the chloroprene rubber. The content of the vulcanizing agent is, for example, 0.1, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, and may be within a range between any two of the numerical values exemplified here. A vulcanizing agent can be used individually by 1 type or in combination of 2 or more types.

1.10 Filler (reinforcing material)
The rubber composition according to the present invention can also contain a filler (reinforcing material) other than silica.
Fillers and reinforcing materials include furnace carbon black such as SAF, ISAF, HAF, EPC, XCF, FEF, GPF, HMF, SRF, modified carbon black such as hydrophilic carbon black, channel black, soot black, FT, Thermal carbon such as MT, acetylene black, ketjen black, clay, talc, and calcium carbonate can be mentioned. These can be used individually by 1 type or in combination of 2 or more types.

In the rubber composition according to one embodiment of the present invention, when the chloroprene rubber is 100 parts by mass, the total amount of silica and fillers (reinforcing materials) other than silica contained in the rubber composition is 2 to 100 parts by mass. Preferably. The rubber composition according to one embodiment of the present invention contains fillers and reinforcing materials other than silica when the total amount of silica and fillers (reinforcing materials) other than silica contained in the rubber composition is 100% by mass. ratio can be 50% by mass or less. The content of the filler/reinforcing material other than silica is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50% by mass, and any one of the numerical values exemplified here is 2 It may be within a range between two. The rubber composition according to one embodiment of the present invention may contain no filler (reinforcement) other than silica.
The rubber composition according to one embodiment of the present invention maintains the effects of the present invention by setting the content of the filler other than silica within the above numerical range, while maintaining the hardness of the vulcanized product / vulcanized molded product. can be improved.

1.11 Lubricant/Processing Aid The rubber composition according to the present invention may further contain a lubricant/processing aid. Lubricants and processing aids are mainly added to improve processability, such as making it easier for the rubber composition to separate from rolls, molding dies, extruder screws, and the like. Examples of lubricants and processing aids include fatty acids such as stearic acid, paraffin-based processing aids such as polyethylene, fatty acid amides, vaseline, and factice. These can be used individually by 1 type or in combination of 2 or more types. The rubber composition according to the present invention can contain 15 parts by mass or less of a lubricant/processing aid when the chloroprene rubber contained in the rubber composition is 100 parts by mass, and can also be 10 parts by mass or less. . The content of the lubricant/processing aid is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, where It may be in a range between any two of the numerical values given. The rubber composition according to the present invention may contain no lubricant/processing aid.

1.12 Sulfur/Vulcanization Accelerator The rubber composition according to the present invention may contain sulfur and a vulcanization accelerator. Also, the rubber composition according to the present invention may be free of sulfur and vulcanization accelerator. When the chloroprene rubber contained in the rubber composition is 100 parts by mass, the sulfur/vulcanization accelerator can be included in 5.0 parts by mass or less. The content of sulfur/vulcanization accelerator is, for example, 0, 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 , 4.0, 4.5, 5.0 parts by mass, and may be within a range between any two of the numerical values exemplified here.

The type of vulcanization accelerator is not particularly limited as long as it does not impair the effects of the present invention. The vulcanization accelerator is preferably a vulcanization accelerator that can be used for vulcanization of chloroprene rubber. One or more vulcanization accelerators can be freely selected and used.
Examples of vulcanization accelerators include thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based accelerators.

Thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide. mentioned.
Dithiocarbamate-based vulcanization accelerators include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, and copper dimethyldithiocarbamate. , ferric dimethyldithiocarbamate, tellurium diethyldithiocarbamate, and the like.
Thiourea-based vulcanization accelerators include ethylenethiourea, diethylthiourea (N,N'-diethylthiourea), trimethylthiourea, diphenylthiourea (N,N'-diphenylthiourea), 1,3-trimethylene-2-thiourea, and the like. and thiourea compounds.
Guanidine-based vulcanization accelerators include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and dicatechol borate di-o-tolylguanidine salts. .
Examples of xanthate-based vulcanization accelerators include zinc butylxanthate and zinc isopropylxanthate.
Thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'- morpholinodithio)benzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide and the like.
Examples of triazine-based vulcanization accelerators include 2,4,6-trimercapto-s-triazine.
These can be used individually by 1 type or in combination of 2 or more types.

1.13 Plasticizer/Softener The rubber composition according to the present invention may contain a plasticizer/softener. The plasticizer/softener is added to adjust the processability of the unvulcanized rubber composition and the flexibility of the vulcanized product and vulcanized molding after vulcanization. The plasticizer/softener is not particularly limited as long as it is compatible with rubber. Plasticizers and softeners include vegetable oils such as rapeseed oil, linseed oil, castor oil and coconut oil, phthalate plasticizers, DUP (diundecyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DOTP ( dioctyl terephthalate), DOS (dioctyl sebacate), DBS (dibutyl sebacate), DOA (dioctyl adipate), DINCH (diisononyl 1,2-cyclohexanedicarboxylate), TOP (trioctyl phosphate), TBP (tributyl phosphate) phate), ether ester compounds, aromatic oils, naphthenic oils, lubricating oils, process oils, paraffin, liquid paraffin, vaseline, and petroleum plasticizers such as petroleum asphalt. These can be used individually by 1 type or in combination of 2 or more types.

The rubber composition according to one embodiment of the present invention can contain 50 parts by mass or less of a plasticizer/softener per 100 parts by mass of the chloroprene rubber contained in the rubber composition. The content of the plasticizer/softener is, for example, 0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 parts by mass. It may be in a range between any two of the numbers. A rubber composition according to an embodiment of the present invention may also be free of plasticizer.

1.14 In addition to the above-described components, the rubber composition according to the present invention may contain components such as anti-aging agents, antioxidants, stabilizers, flame retardants, vulcanization retarders, etc. to the extent that the effects of the present invention are not impaired. can be further included in
Anti-aging agents and antioxidants include ozone anti-aging agents, phenol anti-aging agents, amine anti-aging agents, acrylate anti-aging agents, imidazole anti-aging agents, metal carbamates, waxes, and phosphorus anti-aging agents. agents, sulfur-based antioxidants, and the like. Examples of imidazole antioxidants include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole and zinc salts of 2-mercaptobenzimidazole.
The rubber composition according to the present invention can contain 0.1 to 10 parts by mass of an anti-aging agent and an antioxidant per 100 parts by mass of the chloroprene rubber contained in the rubber composition.

2. A rubber composition according to one embodiment of the present invention comprises a chloroprene rubber, silica, a maleimide compound, an organic peroxide, a silane coupling agent, and other required components at a vulcanization temperature. It is obtained by kneading at the following temperature. As a device for kneading the raw material components, conventionally known kneading devices such as a mixer, a Banbury mixer, a kneader mixer, and an open roll can be used.

3. Characteristics of rubber composition (heat resistance of vulcanized molding)
The rubber composition according to one embodiment of the present invention is a vulcanized molded article molded according to JIS K6299 with an elongation at break EB ₀ measured based on JIS K6251, and the vulcanized molded article is heated at 150 ° C. for 144 hours. The change in elongation at break ΔEB calculated by the following formula is preferably −68 or more, where the elongation at break measured according to JIS K6251 after slicing is EB _i .
ΔEB = (EB _i - EB ₀ )/EB ₀ × 100
The change in elongation at break ΔEB is, for example, −68, −67, −66, −65, −60, −55, −50, −45, −40. may be within the range of

(Compression set of vulcanized molded body)
The rubber composition according to one embodiment of the present invention is a vulcanized molded body obtained by press vulcanization molding under the conditions of 180 ° C. x 30 minutes, based on JIS K 6262: 2013, 150 ° C., 72 hours test. The compression set measured under the conditions is preferably 34 or less.
The compression set is, for example, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, within the range between any two of the numerical values exemplified herein. There may be.

4. Unvulcanized Molded Article, Vulcanized Product, and Vulcanized Molded Article The unvulcanized molded article according to the present embodiment uses the rubber composition according to the present embodiment. It is a molded product (molded product) in a sulfuric state). The method for producing an unvulcanized molded article according to this embodiment includes a step of molding the rubber composition (unvulcanized state) according to this embodiment. The unvulcanized molded article according to this embodiment is made of the rubber composition (unvulcanized state) according to this embodiment.

The vulcanizate according to this embodiment is a vulcanizate of the rubber composition according to this embodiment. A method for producing a vulcanizate according to the present embodiment includes a step of vulcanizing the rubber composition according to the present embodiment.

The vulcanized molded article according to this embodiment is a vulcanized molded article of the rubber composition according to this embodiment. The vulcanized molded article according to the present embodiment uses the vulcanized material according to the present embodiment, and is a molded article (molded article) of the vulcanized material according to the present embodiment. The vulcanized molding according to this embodiment is made of the vulcanizate according to this embodiment.

The vulcanized molded article according to the present embodiment can be obtained by molding a vulcanized product obtained by vulcanizing the rubber composition (unvulcanized state) according to the present embodiment. It can also be obtained by vulcanizing the molded article obtained by molding the rubber composition (unvulcanized state) according to. The vulcanized molded article according to this embodiment can be obtained by vulcanizing the rubber composition according to this embodiment after or during molding. A method for manufacturing a vulcanized molded article according to the present embodiment includes a step of molding a vulcanized article according to the present embodiment or a step of vulcanizing an unvulcanized molded article according to the present embodiment.

The vulcanizate and the vulcanized molded product according to one embodiment of the present invention preferably have a change in elongation at break ΔEB and a permanent compression set within the above numerical ranges.

The unvulcanized molded article, vulcanized article and vulcanized molded article according to the present embodiment can be used as rubber parts in various industrial fields such as buildings, constructions, ships, railroads, coal mines and automobiles. A vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set after heating, and therefore can be used as various members requiring these properties. The rubber composition according to one embodiment of the present invention can be used as rubber parts in various industrial fields such as buildings, structures, ships, railroads, coal mines, automobiles, etc. , hose materials, rubber molds, gaskets, rubber rolls, industrial cables, industrial conveyor belts, sponges and other rubber parts. The rubber composition according to one embodiment of the present invention can be used for various members that require excellent heat resistance and/or excellent compression set, especially sealing materials and gaskets, by taking advantage of its properties. , can be suitably used for packing, etc.

(Rubber parts for automobiles)
BACKGROUND ART Automotive rubber members include gaskets, oil seals, packings, and the like, and are parts in machines and devices that prevent the leakage of liquids and gases, and the intrusion of dirt and foreign matter such as rainwater and dust. Specifically, there are gaskets used for stationary applications, and oil seals and packings used for moving parts. For gaskets whose sealing portions are fixed with bolts or the like, various materials are used depending on the purpose, as opposed to soft gaskets such as O-rings and rubber sheets. Packings are also used for shafts of pumps and motors, rotating parts such as the movable parts of valves, reciprocating parts such as pistons, connecting parts of couplers, water shut-off parts of faucets, and the like. The vulcanizate of the rubber composition according to one embodiment of the present invention is not observed to bleed and has excellent elongation at break and compression set after heating. It is possible to manufacture a seal that is

(hose material)
The hose material is a bendable tube, and specifically includes high/low pressure hoses for water, oil, air, steam, and hydraulic pressure. Since the vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set after heating, for example, it is possible to manufacture a hose material that is used by taking advantage of these properties. .

(rubber mold)
Rubber molds include anti-vibration rubber, damping materials, and boots. Anti-vibration rubber and damping material are rubbers that prevent transmission of vibration. Damper, engine mount, muffler hanger, etc. The rubber composition of the present invention can increase the tensile strength of vibration-isolating rubbers and vibration-damping materials. As a result, it is possible to produce vibration-isolating rubbers and vibration-damping materials that can be used even in applications where high load is applied, which has been difficult with conventional rubber compositions.
Also, the boot is a bellows-shaped member whose outer diameter gradually increases from one end to the other end. There are boots for ball joint covers (dust cover boots) and boots for rack and pinion gears. Since the vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set, it is possible to manufacture boots that are used by taking advantage of these properties.

(Gasket, etc.)
Gaskets, oil seals, and packings are parts used in machinery and equipment to prevent leaks of liquids and gases, rainwater, dust, and other dirt and foreign matter from entering the interior. Specifically, they are used for stationary applications. There are gaskets and oil seals and packings used for moving parts and movable parts. For gaskets whose sealing portions are fixed with bolts or the like, various materials are used depending on the purpose, as opposed to soft gaskets such as O-rings and rubber sheets. Packings are also used for shafts of pumps and motors, rotating parts such as the movable parts of valves, reciprocating parts such as pistons, connecting parts of couplers, water shut-off parts of faucets, and the like. Since the vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set, it is possible to manufacture, for example, seals that are used by taking advantage of these properties.

(rubber roll)
A rubber roll is manufactured by adhesively coating a metal core such as an iron core with rubber, and is generally manufactured by spirally winding a rubber sheet around a metal iron core. For rubber rolls, rubber materials such as NBR, EPDM, CR, etc. are used according to the required characteristics of various applications such as paper manufacturing, various metal manufacturing, film manufacturing, printing, general industrial use, agricultural equipment such as hulling, and food processing. used. Since CR has good mechanical strength to withstand the friction of objects to be conveyed, it is used for a wide range of rubber roll applications. Since the rubber composition of the present invention is excellent in elongation at break and compression set, it is possible to manufacture a rubber roll by taking advantage of these properties.

(industrial cable)
Industrial cables are linear members for transmitting electrical and optical signals. A good conductor such as copper or copper alloy or an optical fiber is coated with an insulating coating layer, and a wide variety of industrial cables are manufactured depending on the structure and installation location. Since the vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set after heating, for example, it is possible to manufacture industrial cables that are used by taking advantage of these characteristics. can.

(industrial conveyor belt)
Industrial conveyor belts come in rubber, resin, and metal belts, and are selected according to a wide variety of usage methods. Among these, rubber conveyor belts are inexpensive and widely used. The vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set after heating. can be done.

(sponge)
Sponge is a porous material with a myriad of fine holes inside, and is specifically used for vibration-proof members, sponge seal parts, wet suits, shoes, and the like. The rubber composition of the present invention can increase the tensile strength of sponge. In addition, it is possible to improve the flame retardancy of the sponge because chlorine-based rubber is used. The vulcanizate of the rubber composition according to one embodiment of the present invention is excellent in elongation at break and compression set after heating. sponge can be produced. Furthermore, the hardness of the resulting sponge can be adjusted as appropriate by adjusting the content of the foaming agent.

Methods for molding the rubber composition (unvulcanized state) and the vulcanized product according to the present embodiment include press molding, extrusion molding, calendar molding, and the like. The temperature for vulcanizing the rubber composition may be appropriately set according to the composition of the rubber composition, and may be 140 to 220°C or 160 to 190°C. The vulcanization time for vulcanizing the rubber composition may be appropriately set depending on the composition of the rubber composition, the shape of the unvulcanized molding, etc., and may be 10 to 60 minutes.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

<Method for producing acrylonitrile-containing chloroprene rubber>
24 parts by mass of chloroprene (monomer), 24 parts by mass of acrylonitrile (monomer), 0.5 parts by mass of diethylxanthogen disulfide, and 200 parts by mass of pure water were placed in a 3 L polymerization vessel equipped with a heating/cooling jacket and a stirrer. , Potassium rosinate (manufactured by Harima Chemicals Co., Ltd.) 5.00 parts by weight, sodium hydroxide 0.40 parts by weight, and sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) 2.0 parts by weight was added. Next, after adding 0.1 part by mass of potassium persulfate as a polymerization initiator, emulsion polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. The above-mentioned chloroprene is added in portions from 20 seconds after the start of polymerization, the amount of added portions is adjusted with a solenoid valve based on the change in the heat quantity of the refrigerant for 10 seconds from the start of polymerization, and the flow rate is readjusted every 10 seconds thereafter. continuously. When the polymerization rate with respect to the total amount of chloroprene and acrylonitrile reached 50%, 0.02 parts by mass of phenothiazine as a polymerization terminator was added to terminate the polymerization. Thereafter, unreacted monomers in the reaction solution were removed under reduced pressure to obtain an acrylonitrile-containing chloroprene-based latex containing a chloroprene-acrylonitrile copolymer.

The above-mentioned polymerization rate [%] of the acrylonitrile-containing chloroprene-based latex was calculated from the dry mass when the chloroprene-based latex was air-dried. Specifically, it was calculated from the following formula (A). In the formula, the "solid content concentration" is the solid content concentration [% by mass] after heating 2 g of the sampled chloroprene-based latex at 130 ° C. and excluding volatile components such as solvent (water), volatile chemicals, and raw materials. is. The "total charged amount" is the total amount [g] of raw materials, reagents and solvent (water) charged into the polymerization vessel from the start of polymerization to a certain time. The "evaporation residue" is the mass [g] of chemicals remaining as solid content together with the polymer without being volatilized under conditions of 130°C among the chemicals and raw materials charged up to a certain time from the start of polymerization. The "amount of monomer charged" is the total amount [g] of the amount of the monomer initially charged in the polymerization vessel and the amount of the monomer gradually added from the start of the polymerization to a certain time. In addition, the "monomer" here is the total amount of chloroprene and acrylonitrile.
Polymerization rate = {[(total charged amount x solid content concentration/100) - evaporation residue]/ charged amount of monomer} x 100 (A)

After adjusting the pH of the above acrylonitrile-containing chloroprene-based latex to 7.0 using acetic acid or sodium hydroxide, the acrylonitrile-containing chloroprene-based latex is frozen and coagulated on a metal plate cooled to -20 ° C. to break emulsification. A sheet was obtained by After the sheet was washed with water, it was dried at 130° C. for 15 minutes to obtain a solid acrylonitrile-containing chloroprene rubber.

The content of acrylonitrile monomer units contained in the acrylonitrile-containing chloroprene rubber was calculated from the content of nitrogen atoms in the chloroprene-acrylonitrile copolymer rubber. Specifically, using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Service, Ltd.), the content of nitrogen atoms in 100 mg of chloroprene-based rubber was measured, and the content of acrylonitrile monomer units was determined. Calculated.

The elemental analysis described above was performed as follows. The electric furnace temperature was set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column temperature, and 100°C for the detector temperature. flowed. A calibration curve was prepared using aspartic acid (10.52%) with a known nitrogen content as a standard substance.
The acrylonitrile monomer unit content of the acrylonitrile-containing chloroprene rubber obtained by the above production method was 10.0% by mass.

<Production of rubber composition>
Each component was mixed as shown in Tables 1 to 3 and kneaded with an 8-inch open roll to obtain rubber compositions of Examples and Comparative Examples.

Each component used to obtain the rubber composition is as follows.
<Chloroprene rubber>
・Acrylonitrile (AN)-containing chloroprene rubber: Acrylonitrile-containing chloroprene rubber prepared by the above-described manufacturing method ・Mercaptan-modified chloroprene rubber: Mercaptan-modified chloroprene rubber, “S-40V” manufactured by Denka Co., Ltd.

Silica: “ULTRASIL360” manufactured by Evonik Industries AG BET specific surface area: 55 m ² /g
Silica: “Nipsil E-74P” manufactured by Tosoh Silica Co., Ltd. BET specific surface area: 50 m ² /g
Silica: “Nipsil ER-R” manufactured by Tosoh Silica Co., Ltd. BET specific surface area: 78 m ² /g

Silane coupling agent: 3-methacryloxypropylmethoxysilane, "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd. Silane coupling agent having a double bond

Silane coupling agent: N-phenyl-3-aminopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. "KBM-573" Silane coupling agent having a secondary amine

Silane coupling agent: (3-mercaptopropyl)trimethoxysilane, Dow Corning Toray "Z-6062" Mercapto-based

Carbon black: FEF, manufactured by Asahi Carbon Co., Ltd., "Asahi #60"
Organic peroxide: 1,4-bis[(t-butylperoxy)isopropyl]benzene, NOF Corporation, "Perbutyl P-40"
Organic peroxide: butyl 4,4-bis[(t-butyl)peroxy]pentanoate, NOF Corporation, "Perhexa V-40"
Vulcanization accelerator: Trimethylthiourea, Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noccellar TMU"
Maleimide compound (co-crosslinking agent): m-phenylenedimaleimide, Ouchi Shinko Kagaku Kogyo Co., Ltd., "Balnok PM"
Compounds having a thioether structure: thioether plasticizer, Lanxess "Vulkanol OT" (compound A containing one or more thioether structures and two or more ether structures, and one or more thioether structures and three or more ether structures A mixture containing compound B as a main component)
Vulcanizing agent: Zinc oxide, "zinc oxide type 2" manufactured by Sakai Chemical Industry Co., Ltd.
Hydrotalcite (acid acceptor): Mg _0.7 Al _0.3 O _1.15 , Kyowa Chemical Industry Co., Ltd. “KW-2100”
Antiaging agent: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, Ouchi Shinko Kagaku Kogyo Co., Ltd., "Nocrac CD"
Lubricant/processing aid: Stearic acid: "Stearic acid 50S" manufactured by New Japan Chemical Co., Ltd.

<Evaluation of vulcanized molding>
Vulcanized moldings were produced using the rubber compositions described above and evaluated as follows. The results are shown in Tables 1-3.

(Heat resistance (change in elongation at break after heating))
The obtained rubber composition was subjected to press vulcanization under conditions of 180° C. for 20 minutes according to JIS K6299 to prepare a sheet-like vulcanization molding having a thickness of 2 mm.
The obtained sheet was formed into a dumbbell-shaped No. 3 test piece, and the elongation at break EB ₀ was measured based on JIS K6251. Next, after heating the vulcanized molded body at 150° C. for 144 hours, the elongation at break EB _i was measured again based on JIS K6251. The change ΔEB in the elongation at break before and after the heat resistance test was calculated from the elongation at break EB ₀ before heating and the elongation at break EB _i after heating.
ΔEB = (EB _i - EB ₀ )/EB ₀ × 100

(Compression set)
The obtained rubber composition was press-vulcanized under the conditions of 180° C. for 30 minutes to prepare a cylindrical vulcanized molding having a diameter of 29 mm and a height of 12.5 mm. The obtained vulcanized molding was measured for compression set under test conditions of 150° C. for 72 hours based on JIS K 6262:2013.

Claims (10)

1. 100 parts by mass of chloroprene rubber;
   2 to 100 parts by mass of silica having a BET specific surface area of 10 to 120 m ² /g;
   0.1 to 8 parts by mass of a maleimide compound;
   0.1 to 5 parts by mass of an organic peroxide;
   A rubber composition containing 1 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of the silica.
2. The chloroprene rubber is a homopolymer of 2-chloro-1,3-butadiene, or at least one monomer selected from 2,3-dichloro-1,3-butadiene and unsaturated nitrile monomers. The rubber composition of claim 1, comprising a copolymer with 2-chloro-1,3-butadiene.
3. The silane coupling agent contains at least one selected from a silane coupling agent having a double bond in its structure, a silane coupling agent having an amino group, and a silane coupling agent having a double bond and an amino group. 3. The rubber composition of claim 1 or claim 2, comprising:
4. The silane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyl According to Claim 1 or Claim 2, which is at least one silane coupling agent selected from methyldiethoxysilane, 3-(meth)acryloxypropylmethyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. The rubber composition described.
5. 3. The rubber composition according to claim 1, further comprising 0.1 to 20 parts by mass of a hydrotalcite compound with respect to 100 parts by mass of the chloroprene rubber.
6. The maleimide compound is N,N'-o-phenylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-(4,4'-diphenylmethane) Bismaleimide, 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 4-methyl-1,3-phenylenebismaleimide , 1,6′-bismaleimide-(2,2,4-trimethyl)hexane, the rubber composition according to claim 1 or 2, which is at least one maleimide compound selected from hexane.
7. The organic peroxides include dicumyl peroxide, 1,4-bis[(t-butylperoxy)isopropyl]benzene, tert-butyl α-cumyl peroxide, 2,5-dimethyl-2,5-bis(t- At least one selected from butylperoxy)hexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, and butyl 4,4-bis[(t-butyl)peroxy]pentanoate 3. The rubber composition according to claim 1 or 2, which is an organic peroxide of
8. 3. The rubber composition according to claim 1, further comprising 1 to 30 parts by mass of a compound having a thioether structure with respect to 100 parts by mass of the chloroprene rubber.
9. A vulcanizate of the rubber composition according to claim 1 or 2.
10. A vulcanized molding of the rubber composition according to claim 1 or 2.