Rubber composition

Abstract

To provide a rubber member having good sealability even under a condition that a compression force is applied to a packing, a gasket, a weather strip, a bonnet seal, an oil seal or the like.SOLUTION: The rubber composition comprises (A) a crosslinked rubber and (B) a quaternary ammonium compound having a specific structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition containing a quaternary ammonium compound. [Background technology]

[0002] Crosslinked rubbers have been developed that are less likely to suffer from compression set, have excellent thickness recovery, and are suitable for use as sealing materials for various purposes. The crosslink density of crosslinked foam molded products is closely related to compression set, and generally, the higher the crosslink density of a crosslinked foam molded product, the smaller the compression set (Patent Document 1, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-316538 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-52106 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of extensive research, the inventors have found that when a quaternary ammonium compound is used as a vulcanization accelerator for a rubber composition, the crosslink density increases compared to a rubber composition that does not use this compound. The present invention relates to providing a rubber composition having a low compression set. [Means for solving the problem]

[0005] The present invention has the following aspects. [1] A rubber composition comprising (A) a crosslinked rubber and (B) a compound represented by the following formula (I):

[0006] [ka] [In the above formula (I), R 1 represents a hydrocarbon group, and R 2 ~R 4 are the same or different and represent a hydrocarbon group, hydrogen, or -(AO)nH(R 2 ~R 4 In the formula, n may be the same or different, and X represents an organic acid, a halogen atom, or the like. [2] The rubber composition according to [1] above, wherein the crosslinked rubber is a crosslinked product of at least one rubber selected from ethylene propylene rubber and ethylene propylene diene rubber. [3] The rubber composition according to [1], wherein the compound represented by formula (I) is at least one selected from the group consisting of dialkyl(14-18)dimethylammonium chloride, bis(polyoxyalkylene)oleylmethylammonium chloride, and bis(polyoxyalkylene)alkyl(8-18)methylammonium chloride. [4] The rubber composition according to [1] above, further comprising a filler. [5] The rubber composition according to [1] above, wherein (A) a crosslinked rubber is formed using sulfur as a crosslinking agent. [6] The rubber composition according to [1], further comprising a vulcanization accelerator other than the component (B) to form the crosslinked rubber (A). [7] A rubber member made using the rubber composition according to any one of [1] to [6] above. [Effects of the Invention]

[0007] According to the present invention, the compression set of a rubber composition is improved, and the rubber composition can be used to provide rubber members such as packings, gaskets, weather strips, bonnet seals, and oil seals that have good sealing properties even under conditions where compressive force is applied. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail. The rubber composition of the present invention is characterized by containing (A) a crosslinked rubber and (B) a compound represented by the structure of the following formula (I):

[0009] [ka] [In the above formula (I), R 1 represents a hydrocarbon group, and R 2 ~R 4 are the same or different and represent a hydrocarbon group, hydrogen, or -(AO)nH(R 2 ~R 4 In the formula (III), each n may be the same or different. In addition, in the formula (III), X represents an organic acid, a halogen atom, or the like.

[0010] The crosslinked rubber (hereinafter also referred to as "crosslinked rubber A"), which is component (A) used in the rubber composition of the present invention, is not particularly limited, and in addition to crosslinked natural rubber (NR), crosslinked synthetic rubbers such as isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), acrylic rubber (ACM), ethylene acrylic rubber (AEM), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), vinylidene fluoride rubber (FKM), epichlorohydrin rubber (CO), methyl silicone rubber (MQ), vinyl methyl silicone rubber (VMQ), phenyl methyl silicone rubber (PVMQ), and fluorosilicone rubber (FVMQ) can be used. Among these, crosslinked products of ethylene propylene rubber and ethylene propylene diene rubber are excellent in weather resistance, water resistance, cold resistance, ozone resistance, and chemical resistance, and are suitable for rubber members such as sealing materials, etc. The crosslinked rubber A may be used alone or in combination of two or more types.

[0011] The crosslinking agent (also called vulcanizing agent) of the crosslinked rubber A is not particularly limited, and examples thereof include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, thiuram polysulfide, zinc oxide, organic peroxides, quinone dioxime, and alkylphenol resins.

[0012] The compound represented by the following formula (I), which is component (B) used in the rubber composition of the present invention (hereinafter also referred to as "compound B"), is used for the purpose of reducing the compression set of the crosslinked rubber. Although its mechanism of action is not clear, compound B is generally called a quaternary ammonium compound, and these compounds are known to promote the ring-opening of sulfur in the crosslinking agent at temperatures near the vulcanization temperature of the rubber. As a result, it is presumed that the crosslink density of the rubber increases and the compression set decreases, but the present invention is not limited in any way by this presumed mechanism of action. From the viewpoint of affinity with rubber and silica dispersibility, a long-chain alkylamine (R 1 : an alkyl group having 8 to 22 carbon atoms, R 2 and R 3 (Compound B is preferably a compound containing a hydrogen or methyl group). From the viewpoint of affinity with rubber and prevention of scorch (burning), it may also be a compound containing an oxyalkylene group. Compound B may be used alone or in combination of two or more types.

[0013] [ka] [In the above formula (I), R 1 represents a hydrocarbon group, and R 2 ~R 4 are the same or different and represent a hydrocarbon group, hydrogen, or -(AO)nH(R 2 ~R 4 In the formula (III), each n may be the same or different. In addition, in the formula (III), X represents an organic acid, a halogen atom, or the like.

[0014] In the above formula (I), R 1 ~R 4 When R is a hydrocarbon group, the hydrocarbon group may be linear, branched, or cyclic, and examples thereof include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. From the viewpoint of affinity with rubber, the number of carbon atoms in the hydrocarbon group is 1 is preferably 5 to 22, 8 to 20, or 12 to 18, and R 2 ~R 4The number of carbon atoms is preferably 1 to 22, 1 to 18, 1 to 8, or 1 to 4.

[0015] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkylene group, an alkenyl group, an alkenylene group, an alkynyl group, an alkynylene group, etc. Among these, an alkyl group having the above number of carbon atoms is preferred, and examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and an octadecyl group.

[0016] Examples of the alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, and a cyclooctenyl group.

[0017] Examples of aromatic hydrocarbon groups include phenyl, benzyl, phenethyl, tolyl, xylyl, naphthyl, etc. In the tolyl and xylyl groups, the methyl group may be substituted at any of the ortho, meta, and para positions on the benzene ring.

[0018] R 2 ~R 4 -(AO)nH group (R 2 ~R 4 The n's may be the same or different), R 2 ~R 4 In the formula, AO may be the same or different and represent an oxyalkylene group having 1 to 6 carbon atoms. From the viewpoints of affinity with rubber and prevention of scorch (burning), an oxyalkylene group having 2 to 3 carbon atoms is preferred (an oxyethylene group (EO) having 2 carbon atoms, or an oxypropylene group (PO) having 3 carbon atoms). When -(AO)n- contains two or more types of oxyalkylene groups, the arrangement of the oxyalkylene groups may be block or random.

[0019] n represents the average number of moles of AO added, and is generally 1 to 20, with 1 to 5 being optimal from the standpoints of compatibility with rubber and prevention of scorch (burning).

[0020] R 2 ~R 4 When multiple AO additions are present, R 2 ~R 4 In terms of affinity with rubber and prevention of scorch (burning), it is optimal that l+m=1 to 15 in the above formulas (I) and (II), and l+m+o=1 to 15 in the above formula (III), where l, m, and o represent the respective numbers of moles added.

[0021] X represents an organic acid, a halogen atom, or the like, and is particularly preferably a chlorine atom (Cl), or methyl sulfate (CH3SO4), or the like.

[0022] Specific examples of compounds represented by formula (I) include representative products of Lion Specialty Chemicals Co., Ltd. Lipocard C-50 (wherein R 1 : Palm-derived alkyl group (carbon number 8 to 18), R 2 and R 3 and R 4 : methyl group, X: Cl) Lipocard T-50 (in formula (I), R 1 : alkyl group (carbon number 14 to 18), R 2 and R 3 and R 4 : methyl group, X: Cl) Lipocard 18-63 (in formula (I), R 1 : alkyl group (carbon number 16 to 18), R 2 and R 3 and R 4 : methyl group, X: Cl) Lipocard 22-80: (in formula (I), R 1 : Behenyl group (carbon number 22), R 2 and R 3 and R 4 : methyl group, X: Cl) Lipocard 210-80E (in formula (I), R 1 and R 2 : Decyl group (carbon number 10), R 3 and R 4 : methyl group, X: Cl) Lipocard 210-80MSPG (in formula (I), R 1 and R 2 : Decyl group (carbon number 10), R 3 and R 4 : methyl group, X: CH3SO4) Lipocard 2HT flakes: (in formula (I), R 1 and R 2 : alkyl group (carbon number 14 to 18), R 3 and R 4 : methyl group, X: Cl) Lipocard 2HP flakes: (in formula (I), R 1 and R 2 : alkyl group (carbon number 14 to 18), R 3 and R 4 : methyl group, X: Cl) Liposocard O / 12 (in formula (I), R 1 : Oleyl group (carbon number 18), R 2 , R 3 : 2-hydroxyethyl group, R 4 : methyl group, X: Cl) Liposocard C / 12 (in formula (I), R 1 : alkyl group (carbon number 8 to 18), R 2 , R 3 : 2-hydroxyethyl group, R 4 : methyl group, X: Cl) etc.

[0023] As the compound represented by formula (I), the above-mentioned commercially available products may be used, or a product prepared separately from these commercially available products may also be used.

[0024] In the rubber composition of the present invention, the content of compound B is not particularly limited, and may be, for example, 0.001% by mass or more, 0.005% by mass or more, 0.01% by mass or more, or may be, for example, 5% by mass or less, 1% by mass or less, 0.5% by mass or less, relative to 100% by mass of the rubber composition. When the content of compound B is within the above range, the compression set is reduced.

[0025] The uses of the rubber composition of the present invention are not particularly limited, and examples thereof include tires, anti-vibration rubber, belts, hoses, shoe soles, and sealing materials such as packings, gaskets, weather strips, bonnet seals, and oil seals.

[0026] In addition to the above components, the rubber composition of the present invention can also contain compounding agents conventionally used in the rubber industry, such as reinforcing fillers such as carbon black and calcium carbonate, various softening agents such as oil, silane coupling agents, various antioxidants, wax, stearic acid, zinc oxide, and various vulcanization accelerators other than the component (B).

[0027] The rubber composition of the present invention can be produced by any known method. For example, the rubber composition can be produced by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing the mixture by hot pressing, or by extrusion molding and then introducing the mixture into a continuous vulcanization bath. [Example]

[0028] Next, the present invention will be explained in more detail by giving Production Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples in any way.

[0029] The various chemicals used in the examples and comparative examples will be collectively described below. [Raw materials used] EP25: Ethylene propylene rubber, commercially available from ENEOS Materials Corporation Asahi #60: Carbon black, commercially available from Asahi Carbon Co., Ltd. Heavy calcium carbonate: Commercially available product from Maruo Calcium Co., Ltd. Zinc oxide: Commercially available product from Sakai Chemical Industry Co., Ltd. SUNPAR 150S: Paraffin oil, commercially available from Japan Sun Oil Co., Ltd. Sulfur: Commercially available product from Hosoi Chemical Industry Co., Ltd. Stearic acid: commercially available product from Miyoshi Oil & Fat Co., Ltd. VESTA-18: Moisture absorbent, commercially available from Inoue Lime Industry Co., Ltd. Suncerer DM: Thiazole-based vulcanization accelerator, commercially available from Sanshin Chemical Industry Co., Ltd. Sancer PZ: Dithiocarbamate vulcanization accelerator, commercially available from Sanshin Chemical Industry Co., Ltd. Sancerer 22-C: Thiourea-based vulcanization accelerator, commercially available from Sanshin Chemical Industry Co., Ltd. Sancerer TRA: Thiamin-based vulcanization accelerator, commercially available from Sanshin Chemical Industry Co., Ltd. Suncerer M: Thiazole-based vulcanization accelerator, commercially available from Sanshin Chemical Industry Co., Ltd. Liponol 2HP Flakes: A quaternary ammonium compound, commercially available from Lion Specialty Chemicals Co., Ltd. Liponol 2HT Flakes: A quaternary ammonium compound, commercially available from Lion Specialty Chemicals Co., Ltd.

[0030] [Manufacturing method of the example] According to the formulation shown in Table 1, EP25, Asahi #60, heavy calcium carbonate, zinc oxide, SUNPAR 150S, and VESTA-18 were weighed and placed in a Labo Plastomill (Toyo Seiki Seisakusho, Ltd.). After mixing for 2 minutes and 30 seconds at a rotation speed of 15-20 rpm and a temperature of 80-85°C, the rubber was temporarily discharged from the Labo Plastomill. After cooling the Labo Plastomill, the mixed rubber and separately weighed sulfur, stearic acid, various vulcanization accelerators (other than component (B) of the present invention), and a quaternary ammonium compound (component (B) of the present invention) were again placed in the Labo Plastomill and mixed for 2 minutes and 30 seconds at a rotation speed of 15-20 rpm and a temperature of 80-85°C to obtain an unvulcanized rubber composition. The unvulcanized rubber composition was crosslinked (also referred to as vulcanization) by hot pressing for 30 minutes at a pressure of 7 MPa and a temperature of 170°C to obtain the crosslinked rubber composition of Example 1. In Examples 2 to 4, crosslinked rubber compositions were obtained in the same manner as in Example 1, except that the quaternary ammonium compound or the amount thereof was changed. In Comparative Example 1, a crosslinked rubber composition was obtained in the same manner as in Example 1, except that no quaternary ammonium compound was added.

[0031] [Evaluation method] (Compression set) The compression set of the crosslinked rubber composition was measured according to JIS K6262 (2013). The compression ratio was 25%, the test time was 24 hours, and the test temperature was 23°C.

[0032] [Table 1]

[0033] As is clear from Table 1, Examples 1 to 4, which fall within the scope of the present invention, have low and favorable compression sets. The crosslinked rubber composition of the present invention, which has low compression set, can be used for rubber components used in tires, anti-vibration rubber, belts, hoses, shoe soles, and sealing materials such as packings, gaskets, weatherstrips, bonnet seals, and oil seals.

Claims

1. A rubber composition comprising (A) a crosslinked rubber and (B) a compound represented by the following formula (I): 【Chemistry 1】 [In the above formula (I), R １ represents a hydrocarbon group, and R ２ ~R ４ are the same or different and represent a hydrocarbon group, hydrogen, or -(AO)n-H(R ２ ~R ４ In the formula, n may be the same or different, and X represents an organic acid, a halogen atom, or the like.

2. The rubber composition according to claim 1, wherein the crosslinked rubber is a crosslinked product of at least one rubber selected from ethylene propylene rubber and ethylene propylene diene rubber.

3. The rubber composition according to claim 1, wherein the compound represented by formula (I) is at least one selected from dialkyl (14-18) dimethyl ammonium chloride, bis (polyoxyalkylene) oleyl methyl ammonium chloride, and bis (polyoxyalkylene) alkyl (8-18) methyl ammonium chloride.

4. The rubber composition according to claim 1, further comprising a filler.

5. The rubber composition according to claim 1, wherein the crosslinked rubber (A) is formed using sulfur as a crosslinking agent.

6. 2. The rubber composition according to claim 1, wherein the crosslinked rubber (A) is formed by further using a vulcanization accelerator other than the component (B).

7. A rubber member made using the rubber composition according to any one of claims 1 to 6.

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