JP2019026681A - Rubber composition, vulcanizate of the rubber composition and vulcanized molding - Google Patents

Abstract

To provide a rubber composition that has excellent mechanical strength and permanent compression set under a high temperature condition in the field of chloroprene rubber, and also has excellent processing stability, its vulcanizate and molding.SOLUTION: The present invention provides a rubber composition containing, based on a chloroprene rubber 100 pts.mass, a phosphoric acid compound of 0.5-15.0 pts.mass, and at least one of a benzimidazole compound and N-cyclohexylthiophthalimide of 0.05-3.0 pts.mass, respectively, and a vulcanizate of the rubber composition and a vulcanized molding.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition. More specifically, a rubber composition containing chloroprene rubber as a rubber component, which is suitable as a material for rubber products used for power transmission belts, air springs, seals, packings, vibration isolators, hoses, etc., and addition of the rubber composition The present invention relates to a sulfide and a vulcanized molded body.

  Chloroprene-based rubber is excellent in mechanical properties, ozone resistance, and chemical resistance, and is used in a wide range of fields such as automobile parts, adhesives, and various industrial rubber parts by taking advantage of the characteristics. In recent years, the performance required for industrial rubber parts has been remarkably increased. In addition to the improvements in mechanical properties, ozone resistance, and chemical resistance described above, excellent rubber processing stability, heat resistance, and cold resistance are also provided. Also, compression set is required.

  In order to satisfy the above-mentioned required characteristics, for example, chloroprene rubber is blended with natural rubber and styrene-butadiene copolymer and vulcanized with a specific vulcanization accelerator to improve mechanical strength and compression set. Technology (see Patent Document 1) and technology for vulcanizing chloroprene rubber using an organic peroxide and a co-crosslinking agent in order to improve heat resistance and compression set of the vulcanizate (see Patent Document 2) Has also been proposed.

JP 2012-111899 A JP-A-7-145269

  However, only the techniques described in Patent Documents 1 and 2 have a problem that any one of ozone resistance, mechanical strength, processing stability, and the like is inferior. For example, blending natural rubber with chloroprene rubber improves mechanical strength, but ozone resistance may deteriorate. Further, when an organic peroxide is used for the chloroprene rubber, the compression set is improved, but the processing stability is remarkably deteriorated. For this reason, there has been a demand for a rubber composition having good mechanical strength and processing stability and excellent compression set.

  Accordingly, the present invention provides a rubber composition, a vulcanized product, and a molded product thereof that have good mechanical strength and compression set under high temperature conditions and excellent processing stability in the field of chloroprene rubber. The main purpose.

  In order to solve the above-mentioned problems, the inventors of the present invention conducted extensive research on the components used in combination with the chloroprene rubber, and as a result, the phosphoric acid compound as a plasticizer was compressed under mechanical strength and high temperature conditions. It has been found that permanent set is improved. However, on the other hand, it has been found that the processing stability is lowered. As a result of further research, among the compounds that adjust the vulcanization rate, a specific amount of benzimidazole compound and / or N-cyclohexylthiophthalimide is used in combination, and the amount of phosphate compound is also specified. By setting it as the range of this, it succeeded in improving process stability, improving the mechanical strength and the compression set under high temperature conditions, and came to complete this invention.

That is, in the present invention, first, with respect to 100 parts by mass of chloroprene rubber,
0.5 to 15.0 parts by mass of a phosphoric acid compound,
0.05-3.0 parts by mass of at least one of a benzimidazole compound and N-cyclohexylthiophthalimide,
A rubber composition containing
In the present invention, with respect to 100 parts by mass of chloroprene rubber,
0.5 to 15.0 parts by mass of a phosphoric acid compound,
0.05 to 3.0 parts by mass of a benzimidazole compound,
0.05-3.0 parts by mass of N-cyclohexylthiophthalimide;
A rubber composition containing
In the rubber composition according to the present invention, the chloroprene rubber may be a chloroprene single polymer, or 2,3-dichloro-1,3-butadiene, acrylonitrile, acrylamide, dimethylacrylamide, butyl acrylate, 2-ethylhexyl acrylate, A copolymer of chloroprene and at least one selected from 2-methoxyethyl acrylate and styrene can be used.
In the rubber composition according to the present invention, the phosphoric acid compound includes trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl At least one selected from diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and tris (nonylphenyl) phosphite can be used.
In the rubber composition according to the present invention, as the benzimidazole compound, at least one selected from 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salt of 2-mercaptobenzimidazole can be used.

In the present invention, next, a vulcanized product obtained by vulcanizing the above-described rubber composition according to the present invention and a vulcanized product obtained by vulcanizing the rubber composition according to the present invention after molding or at the time of molding. A molded body is provided.
The vulcanized molded body according to the present invention can be used as a transmission belt, an air spring, a seal, a packing, a vibration isolator, or a hose.

  According to the present invention, in the field of chloroprene rubber, there are provided a rubber composition having excellent mechanical strength and compression set under high temperature conditions and excellent in processing stability, and a vulcanized product and a molded product thereof. be able to.

  Hereinafter, preferred embodiments for carrying out the present invention will be described. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

<Rubber composition> (first embodiment)
In the rubber composition of the present embodiment, the rubber component is a chloroprene rubber, and a specific amount of a phosphoric acid compound, a specific amount of a benzimidazole compound, a specific amount of N-cyclohexylthiophthalimide, or both. contains. Moreover, in addition to each component mentioned above, an antioxidant, carbon black, a softening agent, a filler, etc. can also be mix | blended with the rubber composition of this embodiment. Hereinafter, each component will be described in detail.

[Chloroprene-based rubber]
The chloroprene rubber constituting the rubber component is obtained by polymerizing a raw material monomer containing chloroprene as a main component and then washing and drying as necessary, and is a product of a polymerization reaction. In addition to chloroprene homopolymers or copolymers of chloroprene and other monomers, emulsifiers, dispersants, catalysts, catalyst activators, chain transfer agents and polymerization inhibitors added during polymerization are included. There may be.

  Examples of the monomer copolymerizable with chloroprene include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, and 2-methoxyethyl acrylate, methyl methacrylate, butyl methacrylate, and 2 -Methacrylic esters such as ethylhexyl methacrylate, hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxymethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and 2,3- Dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, acrylamide, dimethylacrylamide and acrylic Ronitoriru and the like. Among these, 2,3-dichloro-1,3-butadiene, acrylonitrile, acrylamide, dimethylacrylamide, butyl acrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, and styrene are more preferable.

  In addition, the monomer copolymerized with chloroprene is not limited to one type, For example, what copolymerized the 2 or more types of monomer containing chloroprene can also be used. The polymer structure of the chloroprene copolymer is not particularly limited, and may be a block copolymer or a statistical copolymer.

  For example, a statistical copolymer of acrylonitrile and chloroprene is produced by continuously adding chloroprene or intermittently adding 10 or more times after the start of the polymerization reaction. In that case, the time of the polymerization reaction start is t (0), n is an integer of 1 or more, and chloroprene and acrylonitrile of time dt (n) between time t (n-1) and time t (n) Based on the total amount of polymerization conversion, the amount of chloroprene added at time dt (n + 1) between time t (n) and time t (n + 1) is determined, and the ratio of unreacted chloroprene to acrylonitrile is kept constant. It is characterized by keeping.

The above-mentioned “statistical copolymer” is described in J. C. Randall “POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method” Academic Press, New York, 1977, pages 71-78. Or a linear or quadratic Markov statistical model. When the statistical copolymer of acrylonitrile and chloroprene is composed of binary monomers, in the following Mayo-Lewis formula (I), other than chloroprene monomer and chloroprene monomer at the start of polymerization Reactivity ratios r1 and r2 when the ratio to the acrylonitrile monomer is d [M1] / d [M2] and the chloroprene monomer is M1 defined in the following Mayo-Lewis formula (I) , R1 is preferably in the range of 0.3 to 3000, and r2 is preferably in the range of 10 ^{−5 to} 3.0 in order to obtain a statistical copolymer.

  The block copolymer of an acrylate ester and chloroprene includes at least one block of an acrylate ester polymer and one block of a chloroprene polymer, and is represented by the following chemical formula (1) or (2). It has a functional group with a structure.

（化学式（１）中、Ｒ^１は、水素、塩素、置換もしくは無置換のアルキル基、置換もしくは無置換のアルケニル基、置換もしくは無置換のアリール基、又は置換もしくは無置換のヘテロシクリル基を示す。）

(In the chemical 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 heterocyclyl group. )

  In the production method, in the presence of a compound represented by the following chemical formula (3) or (4), an acrylate ester alone, or an acrylate ester and another monomer are subjected to living radical emulsion polymerization to produce an acrylate ester polymer. After synthesizing the block of the coalescence, chloroprene alone or a mixture of chloroprene and another monomer and living radical emulsion polymerization to synthesize the block of the chloroprene polymer, and the following chemical formula (3) or (4) In the presence of the compound represented by the formula, chloroprene alone, or chloroprene and other monomers are added and living radical emulsion polymerization is performed to synthesize a block of chloroprene polymer, and then acrylate ester alone or acrylic A method of synthesizing acrylic acid ester polymer block by mixing living ester emulsion polymer with acid ester and living radical emulsion polymerization Is another.

（化学式（３）中、Ｒ^２は、水素、塩素、置換もしくは無置換のアルキル基、置換もしくは無置換のアルケニル基、置換もしくは無置換のアリール基、又は置換もしくは無置換のヘテロシクリル基を示す。化学式（３）及び（４）中、Ｒ^３〜Ｒ^５はそれぞれ独立に、置換もしくは無置換のアルキル基、置換もしくは無置換の飽和、不飽和もしくは芳香族の炭素環、置換もしくは無置換の飽和、不飽和もしくは芳香族の複素環、有機金属種、又は任意の重合体鎖を示す。）

(In the chemical formula (3), R ² 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 heterocyclyl group. In chemical formulas (3) and (4), R ^{3 to} R ⁵ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted saturated, unsaturated or aromatic carbocyclic ring, a substituted or unsubstituted saturated Represents an unsaturated or aromatic heterocycle, an organometallic species, or any polymer chain.)

  On the other hand, chloroprene rubber is roughly classified into sulfur-modified chloroprene rubber and non-sulfur-modified chloroprene rubber. Non-sulfur-modified rubber is further classified into mercaptan-modified chloroprene rubber and xanthogen-modified chloroprene rubber according to the type of molecular weight modifier. The The sulfur-modified chloroprene rubber is obtained by copolymerizing a raw material monomer containing chloroprene as a main component and sulfur, and plasticizing the obtained copolymer with thiuram disulfide so as to have a predetermined Mooney viscosity.

  On the other hand, mercaptan-modified chloroprene rubber is obtained by using alkyl mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan and octyl mercaptan as molecular weight modifiers. The xanthogen-modified chloroprene rubber can be obtained by using an alkyl xanthogen compound as a molecular weight regulator. The chloroprene rubber compounded in the rubber composition of the present embodiment may be any of the various chloroprene rubbers described above, but mercaptan-modified chloroprene rubber and xanthogen-modified chloroprene rubber are particularly suitable.

  Furthermore, chloroprene rubber can be classified into, for example, a type having a low crystallization rate, a type having a moderate crystallization rate, and a type having a high crystallization rate based on the crystallization rate. The rubber composition of the present embodiment may use any of the above-described types of chloroprene rubber, and can be appropriately selected and used depending on the application.

  Although the method for producing chloroprene rubber is not particularly limited, the raw material monomer may be polymerized by a commonly used emulsion polymerization method in the presence of an emulsifier, a polymerization initiator, a molecular weight modifier and the like. In this case, the emulsifier includes, for example, a saturated or unsaturated aliphatic alkali metal salt having 6 to 22 carbon atoms, an alkali metal salt of rosin acid or disproportionated rosin acid, and a formalin condensate of β-naphthalenesulfonic acid. An emulsifier generally used for emulsion polymerization of chloroprene, such as an alkali metal salt, can be used.

  Polymerization initiators are generally used for emulsion polymerization of chloroprene, such as organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide and tert-butyl hydroperoxide. The polymerization initiator can be used.

  In addition, the polymerization temperature at the time of emulsion polymerization is not particularly limited, but is preferably 0 to 50 ° C., more preferably 20 to 50 ° C. from the viewpoint of productivity and polymerization stability. . Further, the final conversion rate of the monomer is not particularly limited, but is preferably in the range of 60 to 90% from the viewpoint of productivity.

  When the final conversion rate reaches a predetermined range, a small amount of a polymerization inhibitor is added to the polymerization solution to stop the polymerization reaction. In this case, examples of the polymerization inhibitor include thiodiphenylamine, 4-tert Commonly used materials such as -butylcatechol and 2,2-methylenebis-4-methyl-6-tert-butylphenol can be used. Further, after the polymerization reaction, for example, after removing the unreacted monomer by a steam stripping method or the like, the pH of the latex is adjusted, and the polymer is obtained by a conventional method such as freeze coagulation, washing with water and drying with hot air. Can be isolated.

[Phosphoric acid compound: 0.5 to 15.0 parts by mass with respect to 100 parts by mass of the rubber component]
The phosphoric acid compound has an effect as a plasticizer and an anti-aging agent, and improves the mechanical strength of a vulcanized product and a molded vulcanized product, which will be described later, and improves high temperature compression set. However, when the addition amount of the phosphoric acid compound is less than 0.5 parts by mass per 100 parts by mass of the rubber component, an effect sufficient to improve the high temperature compression set cannot be obtained. On the other hand, when the addition amount of the phosphoric acid compound exceeds 15.0 parts by mass per 100 parts by mass of the rubber component, the hardness of the rubber decreases, the high temperature compression set increases, and the mechanical strength decreases. Therefore, the addition amount of a phosphoric acid type compound shall be 0.5-15.0 mass parts per 100 mass parts of rubber components. In particular, in order to further improve the mechanical strength of the vulcanizate and molded vulcanizate described below and further improve the high temperature compression set, 0.5 to 12.0 parts by mass per 100 parts by mass of the rubber component It is preferable that it is 1.0 to 10.0 parts by mass.

  Here, as the phosphoric acid compound, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl Examples include phosphate and tris (nonylphenyl) phosphite. Two or more of these can be used in combination.

[Benzimidazole compound: 0.05 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component]
The benzimidazole compound has an effect as a vulcanization accelerator, and adjusts the vulcanization speed of the chloroprene rubber to improve the processing stability at the time of molding. However, when N-cyclohexylthiophthalimide, which will be described later, is not used, if the amount of benzimidazole compound added is less than 0.05 parts by mass per 100 parts by mass of the rubber component, it is sufficient to improve the processing stability. The effect is not obtained. On the other hand, when the addition amount of the benzimidazole compound exceeds 3.0 parts by mass per 100 parts by mass of the rubber component, the vulcanization rate is increased and the processing stability and the like are lowered. Here, the processing stability is evaluated by the scorch time. The processing stability greatly affects the defect occurrence rate. For example, if the scorch time is short, the frequency of occurrence of molding defects increases due to vulcanization of the unvulcanized compound during molding at high temperature. Therefore, the addition amount of the benzimidazole compound is 0.05 to 3.0 parts by mass per 100 parts by mass of the rubber component. In particular, in order to further improve the processing stability at the time of molding, it is preferably 0.1 to 2.0 parts by mass, particularly 0.1 to 1.0 part by mass per 100 parts by mass of the rubber component. Is more preferable.

  Here, examples of the benzimidazole compound include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, and the like. Two or more of these can be used in combination.

[N-cyclohexylthiophthalimide: 0.05 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component]
N-cyclohexylthiophthalimide has an effect as a scorch inhibitor and adjusts the vulcanization rate of the chloroprene rubber to improve the processing stability during molding. However, when the benzimidazole compound is not used and the amount of N-cyclohexylthiophthalimide added is less than 0.05 parts by mass per 100 parts by mass of the rubber component, it is sufficient to improve the processing stability. The effect is not obtained. On the other hand, when the addition amount of N-cyclohexylthiophthalimide exceeds 3.0 parts by mass per 100 parts by mass of the rubber component, the vulcanization rate becomes too low and the crosslinking density decreases, resulting in mechanical strength and high temperature compression set. descend. Therefore, the addition amount of N-cyclohexylthiophthalimide is 0.05 to 3.0 parts by mass per 100 parts by mass of the rubber component. In particular, in order to further improve the processing stability at the time of molding, it is preferably 0.1 to 2.0 parts by mass, particularly 0.1 to 1.0 part by mass per 100 parts by mass of the rubber component. Is more preferable.

[Others]
Furthermore, in the rubber composition of the present embodiment, various chemicals usually used in the rubber industry, for example, fillers, reinforcing agents, softeners, plasticizers, anti-aging agents, as long as the above-described effects are not impaired. Vulcanizing agents, vulcanization accelerators, scorch inhibitors, processing aids and the like can be blended.

  As the vulcanizing agent that can be added, sulfur, thiourea-based, guanidine-based, thiuram-based, and thiazole-based organic vulcanizing agents that are generally used for vulcanizing chloroprene-based rubbers can be used, but thiourea-based ones are preferable. Examples of the thiourea-based vulcanizing agent include ethylenethiourea, diethylthiourea, trimethylthiourea, triethylthiourea, N, N′-diphenylthiourea, and trimethylthiourea and ethylenethiourea are particularly preferable. It is also possible to use a vulcanizing agent such as a mixture of 3-methylthiazolidinethione-2-thiazole and phenylene dimaleimide, dimethylammonium hydrogen isophthalate or 1,2-dimercapto-1,3,4-thiadiazole derivative. it can. These vulcanizing agents may be used in combination of two or more of those listed above. In addition, simple metals such as beryllium, magnesium, zinc, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, molybdenum, tungsten, tellurium, selenium, iron, nickel, cobalt, osmium, etc. Oxides and hydroxides can be used as vulcanizing agents. Among these vulcanizing agents that can be added, calcium oxide, zinc oxide, antimony dioxide, antimony trioxide, and magnesium oxide are particularly preferable because of their high vulcanizing effect. Two or more of these vulcanizing agents may be used in combination. In addition, it is preferable to add a vulcanizing agent in 0.1 to 15 mass parts in total with respect to 100 mass parts of rubber components.

The filler or reinforcing agent is added to adjust the hardness of the rubber or improve the mechanical strength, and is not particularly limited as long as the effects of the present invention are not impaired. For example, carbon black, silica, clay, Examples include talc and calcium carbonate. Even other inorganic fillers are not particularly limited, alumina such as γ- alumina and α- alumina _{(Al 2 O} 3), alumina monohydrate such as boehmite and diaspore _{(Al 2 O 3 · H 2} O) , Aluminum hydroxide [Al (OH) ₃ ], such as gibbsite and bayerite, aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium carbonate (MgCO ₃ ), talc ( 3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca ( _OH) 2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2} O 3 · 2Si _2), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · 5H 2 O etc.), _(such as Mg ₂ SiO 4, MgSiO ₃₎ magnesium silicate, _(such as Ca 2 SiO ₄₎ calcium silicate, aluminum silicate calcium (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O] , zirconium carbonate _{[Zr (CO 3) 2]} , hydrogen to correct electric charge as various zeolites, Such fine alkali metal or crystalline aluminosilicates containing alkali earth metals may be used. The filler and reinforcing agent may be used alone or in combination of two or more. The blending amount of these fillers and reinforcing agents may be adjusted according to the required physical properties of the rubber composition of the present embodiment and its vulcanized molded product, and is not particularly limited, but the rubber of the present embodiment. Usually, it can be added in a range of 15 to 200 parts by mass in total with respect to 100 parts by mass of the rubber component in the composition.

  The plasticizer is not particularly limited as long as it is a plasticizer compatible with rubber. For example, vegetable oil such as rapeseed oil, linseed oil, castor oil, coconut oil, phthalate plasticizer, DUP (diundecyl phthalate), DOS (Dioctyl sebacate), DOA (dioctyl adipate), ester plasticizer, ether ester plasticizer, thioether plasticizer, aromatic oil, naphthenic oil, lubricating oil, process oil, paraffin, liquid paraffin, petroleum jelly, There are petroleum plasticizers such as petroleum asphalt, and one or more can be used according to the properties required for the rubber composition of the present embodiment and the vulcanized molded body of the composition. The blending amount of the plasticizer is not particularly limited, but it can be blended in a range of generally 3 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the rubber component in the rubber composition of the present embodiment. .

  When kneading or vulcanizing the rubber composition, it is added to improve processing characteristics and surface lubricity, such as making it easier to peel off from rolls, molding dies, extruder screws, etc. Examples of processing aids and lubricants include fatty acids such as stearic acid, paraffinic processing aids such as polyethylene, and fatty acid amides. Only one type of processing aid and lubricant may be used, or two or more types may be used in combination. The addition amount is not particularly limited, but is usually 0.5 parts by mass or more and 5 parts by mass or less in total with respect to 100 parts by mass of the rubber component in the rubber composition of the present embodiment.

  Addition of primary anti-aging agent that scavenges radicals to prevent auto-oxidation and secondary anti-aging agent that renders hydroperoxide detoxified as anti-aging agents that improve heat resistance can do. These anti-aging agents can be added at a ratio of 0.1 to 10 parts by mass, preferably 2 to 5 parts by mass, with respect to 100 parts by mass of the rubber component in the rubber composition. Range. These antioxidants can be used alone or in combination of two or more. Examples of primary anti-aging agents include phenol-based anti-aging agents, amine-based anti-aging agents, acrylate-based anti-aging agents, imidazole-based anti-aging agents, carbamic acid metal salts, and waxes. Examples of the secondary anti-aging agent include phosphorus-based anti-aging agents, sulfur-based anti-aging agents, and imidazole-based anti-aging agents. Although it does not specifically limit as an example of anti-aging agent, N-phenyl- 1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine, p- (p -Toluenesulfonylamido) diphenylamine, N, N'-di-2-naphthyl-p-phenylenediamine, N, 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, 1,1,3- Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4 , 4'-butylidenebis- (3-methyl-6-tert-butylphenol), 2,2-thiobis (4-methyl-6-tert-butylphenol), 7-octadecyl-3- (4'-hydroxy-3 ', 5′-di-tert-butylphenyl) propionate, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, pentaerythritol-tetrakis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexane Diol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Lopionate], 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, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, 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, Tadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ester and 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, tris (nonyl phenyl) phosphite, tris (mixed mono- and di-nonylphenyl) ) Phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, diphenyl nonylphenyl phosphite, triphenyl phosphite, tris (Tridecyl) Fosuf Ite, triisodecyl phosphite, tris (2-ethylhexyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl) penta Erythritol tetraphosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-tert-butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6-tert- Butyl-di-tridecyl phosphite), 2,2'-ethylidenebis (4,6-di-tert-butylphenol) fluorophosphite, 4,4'-isopropylidene-diphenol alkyl (C12-C15) phosphite , Cyclic neopentane tetra Rubis (2,4-di-tert-butylphenylphosphite), cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-phenylphosphite), cyclic neopentanetetraylbis (nonylphenylphosphite) Phyto), bis (nonylphenyl) pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearyl pentaerythritol diphosphite, and hydrogenated bisphenol A pentaerythritol phosphite polymer.

  In order to improve the adhesiveness between the rubber component such as the chloroprene-based rubber and the filler or reinforcing agent and to improve the mechanical strength, a silane coupling agent can be further added. The silane coupling agent may be added when the rubber composition is kneaded, or may be added in the form of a surface treatment with a filler or a reinforcing agent in advance. A silane coupling agent may use only 1 type, or may use 2 or more types together. Although not specifically limited, bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (3-trimethoxynylpropyl) tetrasulfide, bis- (3-methyldimethoxysilylpropyl) tetrasulfide, bis- ( 2-triethoxysilylethyl) tetrasulfide, bis- (3-triethoxysilylpropyl) disulfide, bis- (3-trimethoxysilylpropyl) disulfide, bis- (3-triethoxysilylpropyl) trisulfide, 3-hexa Noylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-o Tanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoyl Ruthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyl Trimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3 Aminopropyltriethoxysilane, γ-grindoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl Benzothiazolyl tetrasulfide, 3-trimethoxysilylpropylmethacryloyl monosulfide, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, isobutyltrimethoxysilane, n -Decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hex Examples include trimethoxysilane, octadecylmethyldimethoxysilane, octadecyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, triphenyl chlorosilane, heptadecafluorodecylmethyldichlorosilane, heptadecafluorodecyltrichlorosilane, and triethylchlorosilane. .

  In addition, the rubber composition of this embodiment can be manufactured by the same method as a normal rubber composition. Specifically, chloroprene rubber, phosphoric acid compound, benzimidazole compound, N-cyclohexylthiophthalimide and other components are kneaded at a temperature below the vulcanization temperature by a kneader such as a kneader, Banbury or roll. Can be obtained.

  As described above in detail, the rubber composition of the present embodiment uses chloroprene rubber as a rubber component, and a specific amount of a phosphoric acid compound, a specific amount of at least one of a benzimidazole compound and N-cyclohexylthiophthalimide. Since it mix | blends, high temperature compression set etc. can be improved, without reducing mechanical strength and process stability. Thereby, the rubber composition from which the vulcanizate excellent in mechanical strength, processing stability, and high-temperature compression set can be obtained can be realized.

<Vulcanized product> (Second embodiment)
The vulcanized product of the present embodiment is obtained by vulcanizing the rubber composition of the first embodiment described above. In that case, the vulcanization method of the rubber composition is not particularly limited, and for example, press vulcanization, injection vulcanization, direct kettle vulcanization, indirect kettle vulcanization, direct steam continuous vulcanization, normal pressure continuous vulcanization. Vulcanization may be performed by a vulcanization method such as vulcanization or continuous vulcanization press.

  Further, vulcanization conditions such as vulcanization temperature and vulcanization time are not particularly limited and can be appropriately set. From the viewpoint of productivity and processing stability, the vulcanization temperature is 130 to 200 ° C. It is preferable to set it as 140 to 190 degreeC. Here, “machining stability” is a machining characteristic evaluated by the scorch time and greatly affects the defect occurrence rate. Specifically, when the scorch time is short, the frequency of occurrence of defective molding is increased because the unvulcanized rubber component is vulcanized during molding at a high temperature.

  Since the vulcanized product of the present embodiment uses the rubber composition of the first embodiment described above, it has good high temperature compression set and excellent mechanical strength and processing stability.

<Molded vulcanizate> (Third embodiment)
The molded vulcanized product of the present embodiment is obtained by molding the rubber composition of the first embodiment described above into a shape suitable for the purpose and vulcanizing it during or after molding. The molding method is not particularly limited, and press molding, injection molding, extrusion molding, and the like can be applied. For example, when the molded body is a transmission belt, an air spring, a seal, packing, a vibration isolating material, a hose or the like, it can be formed by press molding, injection molding, or extrusion molding.

  Since the molded vulcanizate of the present embodiment uses the rubber composition of the first embodiment described above, it has good high temperature compression set and excellent mechanical strength and processing stability.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, the Example demonstrated below shows an example of the typical Example of this invention, and, thereby, the range of this invention is not interpreted narrowly.

  In this example, the components were blended in the compositions shown in Tables 1 and 2 below, and then kneaded using an 8-inch roll to prepare rubber compositions of Examples and Comparative Examples. And each rubber composition of an Example and a comparative example was vulcanized, and the performance was evaluated.

<Evaluation method>
The rubber compositions of Examples 1 to 13 and Comparative Examples 1 to 10 shown in Table 1 and Table 2 below were evaluated by the following methods and conditions.

[Processing stability (Scorch time)]
About each rubber composition of an Example and a comparative example, based on JISK6300, the scorch time in 125 degreeC was measured using the L-shaped rotor. A scorch time of 9 minutes or more was accepted.

[Mechanical strength (tensile strength (TB))]
About each rubber composition of an Example and a comparative example, a test piece is produced based on JIS K 6250 (vulcanization conditions: 170 degreeC x 20 minutes), a tensile test is performed based on JIS K 6251, and each vulcanizate The mechanical strength of was measured. In addition, the thing whose tensile strength (TB) is 17 Mpa or more was set as the pass.

[High-temperature compression set (CS)]
About each rubber composition of an Example and a comparative example, a test piece was produced based on JIS K 6250 (vulcanization conditions: primary vulcanization 170 ° C. × 30 minutes, secondary vulcanization 170 ° C. × 2 hours), and JIS K Based on 6262, compression set of each vulcanizate was measured under conditions of 130 ° C. and 72 hours. A compression set (CS) of 45% or less was accepted.

<Result>
The results are shown in Tables 1 and 2 below.

In addition, each compounding component shown in the said Table 1 and Table 2 is as follows.
[Chloroprene-based rubber]
Acrylonitrile copolymerized chloroprene rubber (manufactured by Denka Co., Ltd., acrylonitrile copolymerization amount 9.5%, statistical copolymer, Mooney viscosity 58, Japanese Patent Laid-Open No. 55-145715)
・ Chloroprene single polymer (M-40 manufactured by DENKA CORPORATION, Mooney viscosity 50)
2,3-dichloro-1,3-butadiene copolymerized chloroprene rubber (S-40V, Denka Co., Ltd., 2,3-dichloro-1,3-butadiene copolymerized amount 10.2%, statistical copolymer, Mooney viscosity 52)

[Plasticizer]
[Phosphate compounds]
・ Tris (2-ethylhexyl) phosphate (TOP manufactured by Daihachi Chemical Industry Co., Ltd.)
・ Tris (nonylphenyl) phosphite (Nocrack TNP manufactured by Ouchi Shinsei Chemical Co., Ltd.)
[Aliphatic dibasic acid ester]
Bis (2-ethylhexyl) sebacate (Daihachi Chemical Industry Co., Ltd., DOS)

[Vulcanization rate modifier]
[Benzimidazole compounds]
・ 2-Mercaptobenzimidazole (Nocrack MB, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
・ 2-Mercaptomethylbenzimidazole (Nocrack, Ouchi Shinsei Chemical Co., Ltd.)
[N-cyclohexylthiophthalimide]
・ N-cyclohexylthiophthalimide (retarder CTP manufactured by Ouchi Shinsei Chemical Co., Ltd.)
[Thiuram compounds]
Tetramethylthiuram disulfide (Ouchi Shinsei Chemical Co., Ltd., Noxeller TT-P)

[Lubricant / Processing aid]
・ Stearic acid (Stearic acid 50S manufactured by Shin Nippon Rika Co., Ltd.)

[Anti-aging agent]
・ Octylated diphenylamine (Nouchi AD-F, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

[Carbon black]
・ Carbon black SRF (Asahi Carbon Corporation Asahi # 50)

[Metal oxide]
・ MgO (Kyowa Mug 150 Kyowa Mug 150)
・ ZnO (2 types of zinc oxide manufactured by Sakai Chemical Industry Co., Ltd.)

[Vulcanization accelerator]
・ Trimethylthiourea (Nouchira TMU manufactured by Ouchi Shinsei Chemical Co., Ltd.)

<Discussion>
As shown in Table 1, Comparative Example 1 containing no phosphoric acid compound and Comparative Example 9 containing an aliphatic dibasic acid ester which is a plasticizer other than the phosphoric acid compound have poor high temperature compression set. It was. On the other hand, even if the phosphoric acid compound was contained, Comparative Example 3 in which the addition amount was less than 0.5 parts by mass was inferior in high temperature compression set. Further, in Comparative Example 4 in which the addition amount of the phosphoric acid compound exceeds 15.0 parts by mass, the hardness of the rubber is low, and the high temperature compression set and mechanical strength (tensile strength (TB)) are inferior. .

  Moreover, the comparative example 2 which contains neither a benzimidazole type compound nor N-cyclohexylthiophthalimide was inferior in processing stability (scorch time). On the other hand, even if it contains a benzimidazole compound, the addition amount is less than 0.05 parts by mass per 100 parts by mass of the rubber component, or even if it contains N-cyclohexylthiophthalimide. The comparative example 6 whose quantity is less than 0.05 mass part per 100 mass parts of rubber components was inferior in processing stability (scorch time). Moreover, the comparative example 10 containing the thiuram-type compound which is another vulcanization rate regulator was inferior in the high temperature compression set.

  In Comparative Example 7 in which the amount of benzimidazole compound added exceeds 3.0 parts by mass per 100 parts by mass of the rubber component, the vulcanization rate becomes too high, and the high temperature compression set and processing stability (scorch time) are high. In Comparative Example 8 in which the amount of N-cyclohexylthiophthalimide added exceeds 3.0 parts by mass per 100 parts by mass of the rubber component, the vulcanization rate becomes too slow and the crosslink density decreases, and high temperature compression set or Mechanical strength (tensile strength (TB)) was inferior.

  On the other hand, per 100 parts by mass of chloroprene rubber, 0.5 to 15.0 parts by mass of the phosphoric acid compound, and 0.05 to 3.0 parts by mass of at least one of the benzimidazole compound and N-cyclohexylthiophthalimide. In Examples 1 to 13 which were partially blended, it was confirmed that a rubber composition excellent in high temperature compression set could be obtained without lowering mechanical strength and processing stability.

  When compared in the examples, as compared with Example 1 or Example 2 using either a benzimidazole compound or N-cyclohexylthiophthalimide as a vulcanization rate modifier, the benzimidazole compound and N- Example 3 and Example 13 in which cyclohexylthiophthalimide was used in combination were superior in processing stability (scorch time).

Claims (8)

For 100 parts by mass of chloroprene rubber,
0.5 to 15.0 parts by mass of a phosphoric acid compound,
0.05-3.0 parts by mass of at least one of a benzimidazole compound and N-cyclohexylthiophthalimide,
Containing a rubber composition. For 100 parts by mass of chloroprene rubber,
0.5 to 15.0 parts by mass of a phosphoric acid compound,
0.05 to 3.0 parts by mass of a benzimidazole compound,
0.05-3.0 parts by mass of N-cyclohexylthiophthalimide;
Containing a rubber composition.   The chloroprene rubber is selected from a chloroprene single polymer or 2,3-dichloro-1,3-butadiene, acrylonitrile, acrylamide, dimethylacrylamide, butyl acrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, and styrene. The rubber composition according to claim 1, which is a copolymer of at least one or more selected from chloroprene.   The phosphoric acid compound is trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, tris The rubber composition according to any one of claims 1 to 3, wherein the rubber composition is at least one selected from (nonylphenyl) phosphite.   The said benzimidazole type compound is at least 1 sort (s) chosen from the zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and 2-mercaptobenzimidazole as described in any one of Claims 1-4. Rubber composition.   A vulcanized product of the rubber composition according to any one of claims 1 to 5.   A vulcanized molded body of the rubber composition according to any one of claims 1 to 5.   The vulcanized molded product according to claim 7, which is a transmission belt, an air spring, a seal, packing, a vibration isolating material, or a hose.