JP4389738B2 - Rubber composition for vulcanization, rubber vulcanizate and rubber product comprising the vulcanizate - Google Patents

Description

  The present invention relates to a rubber composition for vulcanization excellent in heat resistance and ozone resistance after vulcanization based on an oil-resistant polyether rubber, a rubber vulcanizate obtained by vulcanizing the composition, and the same The present invention relates to rubber products such as automobile parts made of vulcanizates.

  Synthetic rubbers such as nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, epihalohydrin rubber, acrylic rubber, and fluororubber have low gas permeability and excellent oil resistance. It is widely used as a material for the rubber, and is particularly preferably used as a material for rubber parts for automobiles.

  In recent years, exhaust gas regulations and fuel transpiration regulations surrounding automobiles have become stricter, and in addition to improving fuel efficiency, improving engine performance and compactness, making parts maintenance-free, etc., improved heat resistance for automotive rubber materials The demands are becoming stricter year by year.

  In order to meet such demands, various antiaging agents for blending with synthetic rubber have been studied and certain results have been obtained. For example, if an organic nickel antioxidant such as nickel dibutyldithiocarbamate is applied to chlorosulfonated polyethylene rubber, nitrile rubber, epichlorohydrin rubber, etc., a vulcanized rubber having excellent heat resistance and ozone resistance can be obtained. That is widely known.

  In addition, the behavior when various metal salts of dithiocarbamic acid are added to styrene-butadiene rubber (SBR) is already known. Among them, only nickel salt of dithiocarbamic acid improves the heat resistance and ozone resistance of synthetic rubber. It is described that it acts as an anti-aging agent that can be used (see Non-Patent Document 1).

  Recently, the toxicity of organic nickel compounds has begun to be a concern, and there is a strong demand for anti-aging agents with excellent heat resistance and ozone resistance that do not use organic nickel compounds in synthetic rubber, especially epichlorohydrin rubber. The present condition is that the anti-aging agent which has the performance which can substitute a compound is not found.

  As a means for improving the heat resistance of epichlorohydrin rubber without using an organic nickel compound, for example, using trithiocyanuric acid as a vulcanizing agent, and combining this with an amine-based antioxidant and a benzimidazole-based antioxidant (See Non-Patent Document 2) and a method of using 6-methylquinoxaline-2,3-dithiocarbonate as a vulcanizing agent and combining it with an amine-based anti-aging agent, a benzimidazole-based anti-aging agent, etc. Various proposals have been made.

  However, although these methods of the prior art have a certain effect for improving heat resistance, there is no description or suggestion about ozone resistance.

On the other hand, a method of adding various peroxide decomposing agents to natural rubber and synthetic rubber has been proposed in order to suppress oxidative degradation of the rubber during use of the tire and a decrease in adhesion to the steel cord (Patent Document). 1). However, this patent document describes the adhesion strength of nonpolar rubber, which is usually used in tires, to steel cords, and only when a specific compound is added to polyether rubber, heat resistance and particularly There is no suggestion that an effect of improving ozone can be obtained.
"Japan Rubber Association Paper", Volume 37, No. 5 (1964), pp. 333-340 "Rubber World" Vol. 227, No. 5, p. 25- Proceedings of “International Rubber Conference 2003” held on June 30, 2003 in Nuremberg, Germany, page 379- JP 11-189679 A

  In view of the above problems, an object of the present invention is to provide a novel composition for vulcanized rubber having both excellent heat resistance and ozone resistance without using a compound that is toxic. is there.

  The inventors of the present invention have made various studies in order to solve the above-mentioned problems. As a result, the reaction product of a specific dithiocarbamic acid derivative and a molybdenum compound was added to the polyether rubber, and then the rubber was vulcanized, which was excellent. It has been found that a rubber vulcanizate having both heat resistance and ozone resistance can be obtained, and the present invention has been completed.

The first invention comprises (a) a polyether rubber, (b) a reaction product of a dithiocarbamic acid derivative represented by the general formula (I) and a molybdenum compound in an aqueous solvent, and (c) a vulcanizing agent. It is a rubber composition for vulcanization | cure characterized by containing.

In the formula, R ¹ and R ² are the same or different and each represents an alkyl group, a cycloalkyl group, or an aralkyl group, and M represents a hydrogen atom or a metal atom.

  M in the general formula (I) is preferably an alkali metal atom, and the molybdenum compound is preferably molybdenum pentachloride.

A second invention is a rubber composition for vulcanization characterized by comprising (a) a polyether rubber, (b) a compound represented by the general formula (II), and (c) a vulcanizing agent. .

In the formula, R ¹ and R ² are the same or different and each represents an alkyl group, a cycloalkyl group, or an aralkyl group.

  In the first and second inventions, preferred polyether rubbers are epihalohydrin rubbers such as epichlorohydrin rubber and epibromohydrin rubber.

  The third invention is a rubber vulcanizate obtained by vulcanizing the rubber composition for vulcanization of the first and second inventions.

  4th invention is a rubber product which consists of a rubber vulcanizate of 3rd invention. Typical examples of rubber products are automobile parts.

  Hereinafter, the configuration of the present invention will be described in more detail.

In the definitions of R ¹ and R ^{2 in} the general formulas (I) and (II), the alkyl group is a lower alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, etc., to dodecyl, Various alkyl groups up to higher alkyl such as nonyl, ralyl, stearyl and the like may be used, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 2 to 18 carbon atoms.

  The cycloalkyl group preferably has 3 to 10 carbon atoms, such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like.

  The aralkyl group is preferably one having 7 to 10 carbon atoms, such as benzyl or phenethyl.

  The polyether rubber used in the present invention is a synthetic rubber obtained by ring-opening polymerization of an oxirane compound. Examples of oxirane compounds include ethylene oxide, propylene oxide, styrene oxide, methyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, epichlorohydrin, epibromohydrin, glycidyl acetate, allyl glycidyl ether, glycidyl methacrylate, butadiene mono An oxide etc. can be mentioned, These are used for (co) polymerization individually or in combination of 2 or more types. Moreover, you may use the blend formed by mixing 2 or more types of polyether rubber.

  In the present invention, among these polyether rubbers, epichlorohydrin homopolymer, epichlorohydrin-allyl glycidyl ether copolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-ethylene oxide-allyl Epihalohydrin rubbers typified by glycidyl ether terpolymers are preferably used.

  The reaction product used in the first invention is a reaction product of a dithiocarbamic acid derivative represented by the general formula (I) and a molybdenum compound in an aqueous solvent. This reaction product is a salt formed by the reaction of a dithiocarbamic acid derivative of general formula (I) and a molybdenum compound. When the dithiocarbamic acid derivative of the general formula (I) is a compound of M = alkali metal atom and the molybdenum compound is molybdenum pentachloride, the preferred molar ratio of the latter to the former subjected to the reaction is 1: 3 to 1: 6. It is. The reaction can be performed at normal temperature and normal pressure, and the reaction time is appropriately determined from the progress of the reaction.

  In the vulcanized rubber composition of the first invention, the amount of the reaction product used is usually 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the polyether rubber.

  Examples of the compound represented by the general formula (II) used in the second invention include molybdenum diethyldithiocarbamate, molybdenum dibutyldithiocarbamate, molybdenum dibenzyldithiocarbamate, molybdenum dihexyldithiocarbamate, molybdenum dioctyldithiocarbamate, didodecylethyldithiocarbamate. Examples thereof include molybdenum, molybdenum dinonyldithiocarbamate, molybdenum dilauryldithiocarbamate, and molybdenum distearyldithiocarbamate. The compound represented by the general formula (II) may be a commercially available product such as “Adeka Sakura Lube 100”, “Adeka Sakura Lube 165”, “Adeka Sakura Lube 600” manufactured by Asahi Denka Co., Ltd.

  In the vulcanized rubber composition of the second invention, the amount of the compound represented by the general formula (II) is usually 0.1 to 5 parts by weight, preferably 0.2 to 3 parts per 100 parts by weight of the polyether rubber. Parts by weight.

  As the vulcanizing agent used in the first and second inventions, any vulcanizing agent can be used as long as it can vulcanize (crosslink) the polyether rubber used in the present invention. When the polyether rubber is obtained by copolymerizing an oxirane compound having an unsaturated group such as allyl glycidyl ether, glycidyl methacrylate, butadiene monoxide, the vulcanizing agent is, for example, sulfur, tetramethylthiuram disulfide, disulfide. Sulfur vulcanizing agents such as pentamethylene thiuram tetrasulfide and morpholine disulfide, oxime vulcanizing agents such as parabenzoquinone dioxime and benzoylquinone dioxime, resin vulcanizing agents such as polymethylolphenol and alkylphenol formaldehyde resin, trichloro Chlorine-containing compound vulcanizing agents such as melamine, hexachloropentadiene, benzotrichloride, dicumyl peroxide, 1,3-bis (tert-butylperoxyisopropyl) benzene, n-butyl- 4- bis (tert- butylperoxy) valerate, 2,5-dimethyl-2,5-di (tert- butylperoxy) hexane that is an organic peroxide vulcanizing agent, such as preferred. These are appropriately selected according to the polyether rubber used, and are used alone or in combination of two or more.

  These vulcanizing agents are used in combination with known vulcanization accelerators, vulcanization accelerating aids (such as zinc white, stearic acid, zinc stearate, etc.), crosslinking aids, retarders and the like for diene rubbers. Also good.

  When the polyether rubber is a (co) polymer of a halogen-containing oxirane compound such as epichlorohydrin or epibromohydrin, the vulcanizing agent is, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, p-phenylenediamine, Amine-based crosslinking agents such as hexamethylenediamine carbamate, ethylenethiourea, 1,3-diethylthiourea, thiourea-based vulcanizing agents such as trimethylthiourea, 2,5-dimercapto-1,3,4-thiadiazole, 2,5-dimercapto -Thiadiazole vulcanizing agents such as 1,3,4-thiadiazole-5-thiobenzoate, 2,4,6-trimercapto-1,3,5-triazine, 1-hexylamino-3,5-dimercaptotriazine 1-dibutylamino-3,5-dimercapto Triazine, triazine vulcanizing agents such as 1-phenylamino-3,5-dimercaptotriazine, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 5,6-dimethylquinoxaline- 2,3-dimercaptoquinoxaline derivative vulcanizing agent such as 2,3-dithiocarbonate, pyrazine-2,3-dithiocarbonate, 5-methyl-2,3-dimercaptopyrazine, 5,6-dimethyl-2, It must be a 2,3-dimercaptopyrazine derivative vulcanizing agent such as 3-dimercaptopyrazine or 5-methylpyrazine-2,3-dithiocarbonate, or a bisphenol crosslinking agent such as bisphenol A, bisphenol AF, or bisphenol S. Is preferred.

  These vulcanizing agents may be used in combination with known vulcanization accelerators, retarders and the like. Examples of vulcanization accelerators include sulfur, thiuram sulfides, morpholine sulfides, amines, weak acid salts of amines, basic silica, quaternary ammonium salts, quaternary phosphonium salts, polyfunctional vinyl compounds, mercaptobenzothiazoles. , Sulfenamides, dimethiocarbamates and the like. Examples of the retarder include N- (cyclohexylthio) phthalimide, organic zinc compound, acidic silica, sulfonamide compound and the like.

In both the (co) polymer of the unsaturated group-containing oxirane compound and the (co) polymer of the halogen-containing oxirane compound, the amount of the vulcanizing agent is usually 0.1 per 100 parts by weight of the polyether rubber. -10 parts by weight, preferably 0.3-5 parts by weight. If the blending amount is less than this range, vulcanization (crosslinking) is insufficient, and if it exceeds this range, it is not economical. The amount of additives such as vulcanization accelerator, vulcanization accelerator, crosslinking aid, retarder, etc. is 0 to 10 parts by weight, for example 0.1 to 5 parts by weight, based on 100 parts by weight of the polyether rubber. is there.

  When the polyether rubber contains a halogen, it is preferable to combine an acid acceptor with the vulcanizing agent. Examples of the acid acceptor include magnesium oxide, magnesium hydroxide, aluminum hydroxide, barium hydroxide, sodium carbonate, magnesium carbonate, barium carbonate, quicklime, slaked lime, calcium carbonate, calcium silicate, sodium stearate, potassium stearate, Calcium stearate, zinc stearate, calcium phthalate, calcium phosphite, zinc white, tin oxide, tin stearate, basic tin phosphite, zeolites, aluminophosphate type molecular sieve, layered silicate, basic silica, synthesis A hydrotalcite, a Li-Al type inclusion compound, etc. can be mentioned. The compounding quantity of an acid acceptor is 0-30 weight part normally with respect to 100 weight part of polyether rubber, Preferably it is 0.1-10 weight part.

  The reaction product in the first invention and the compound (II) in the second invention work as an anti-aging agent. By using these together with an anti-aging agent known for synthetic rubber, The heat resistance of can be further improved. Known anti-aging agents include, for example, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, phenyl-1- Naphthylamine, alkylated diphenylamine, 4-4′-bis (α, α-dimethylbenzyl) diphenylamine, N, N′-di-2-naphthyl-p-phenylenediamine, N, N′-diphenyl-p-phenylenediamine, Amine antioxidants such as N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine and diphenylamine-α-methylstyrene, hydridoquinone, 2,6-di-t-butyl-4-methyl Phenol, styrenated phenol, 4,4′-thiobis (3-methyl-6-tert-butylphenol), pentaerythritol— Trakis {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate}, n-octadecyl-3- (4′-hydroxy-3,5-di-t-butylphenyl) propionate, 4, 4'-butylidenebis (3-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2-hydroxynaphthalene-3-carbyl-2'-methylanilide Phenol aging inhibitors such as 2-t-butyl-6- (3′-t-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl acrylate, 2-mercaptobenzimidazole, 2- Benzimidazole anti-aging agents such as mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, Thiourea-based antioxidants such as butylthiourea and 1,3-bis (dimethylaminopropyl) -2-thiourea, phosphite-based antioxidants such as tris (nonylphenyl) phosphite and triphenylphosphite, Organic thioacid antioxidants such as lauryl thiodipropionate and distearyl thiodipropionate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6) , 6-pentamethyl-4-piperidyl) sebacate and the like, and two or more of these anti-aging agents can be used in combination.

  In the rubber composition for vulcanization of the present invention, compounding agents other than those usually used in the technical field, such as lubricants, fillers, reinforcing agents, plasticizers, processing aids, flame retardants, foaming agents, A foaming aid, a conductive agent, an antistatic agent, a pigment, a tackifier, and the like can be arbitrarily blended as necessary. Furthermore, it is also possible to carry out blending of resins, rubbers and the like, which is usually performed in the technical field.

  In order to produce the rubber composition for vulcanization according to the present invention, the polyether rubber is prevented from aging by using any mixing means conventionally used in the field of polymer processing, such as a mixing roll, a Banbury mixer, various kneaders and the like. Mixing agents, vulcanizing agents and other compounding agents. By vulcanizing the obtained rubber composition for vulcanization, a rubber product made of a rubber vulcanizate can be produced. The temperature and time required for vulcanization are appropriately set according to the type of polyether rubber, the type of vulcanizing agent, etc., but are usually in the range of a temperature of 100 to 250 ° C. and a time of 0.5 to 300 minutes. As a method for vulcanization molding, compression molding using a mold, injection molding, steam can, air bath, heating by infrared rays or microwaves can be appropriately selected and used.

  The rubber composition for vulcanization according to the present invention can be widely applied to fields where oil-resistant synthetic rubber is used. For example, it is possible to obtain rubber products such as various fuel-based laminated hoses for automobiles, air-based laminated hoses, tubes, belts, diaphragms, seals, etc., and rubber products such as general industrial equipment / devices from the same composition. it can. Among these, the rubber vulcanizate according to the present invention can be suitably applied to rubber parts for automobiles, taking advantage of its excellent heat resistance and ozone resistance.

  Moreover, since the rubber composition for vulcanization | cure of this invention does not contain the organic nickel compound which is anxious about the influence on a human body, there also exists an advantage that the health hazard of a rubber product manufacturer and a rubber product user can be suppressed.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Reference example 1
Reaction product of diethyldithiocarbamate and molybdenum compound Add 52.3 g of sodium hydroxide and 113 ml of water to a 3 liter glass reaction vessel equipped with a dropping funnel, temperature controller and stirrer, and dissolve sodium hydroxide in water. Under stirring, 91.8 g of diethylamine was added. To the obtained suspension, 106.3 g of carbon disulfide was dropped over 2 hours while adjusting the temperature in the reactor to 20 to 35 ° C., and stirring was continued at the same temperature for 2 hours. The aqueous solution of sodium diethyldithiocarbamate thus obtained was diluted by adding 2300 ml of water, and 68 g of molybdenum pentachloride powder was added in small portions over 2 hours while adjusting the temperature to 35 ° C. After stirring for 30 minutes at the same temperature, the obtained precipitate was filtered, washed with water and dried to obtain 96.2 g of a powder having a dark purple color.

Reference example 2
Reaction product of dibenzyldithiocarbamate and molybdenum compound 39.3 g of sodium hydroxide and 910 ml of water were added to a 3 liter glass reaction vessel equipped with a dropping funnel, a temperature controller and a stirrer. Dissolve and add 180 g of dibenzylamine under stirring. To the resulting suspension, 74.6 g of carbon disulfide was added dropwise over 2 hours while adjusting the temperature in the reactor to 20 to 35 ° C., and stirring was continued for 2 hours at the same temperature. The aqueous solution of sodium dibenzyldithiocarbamate thus obtained was diluted by adding 1700 ml of water, and 50 g of molybdenum pentachloride powder was added to this diluted solution little by little over 2 hours while adjusting the temperature to 35 ° C. After stirring for 30 minutes at the same temperature, the resulting precipitate was filtered, washed with water, and dried to obtain 277 g of a powder having a dark purple color.

Examples 1 to 3, Comparative Examples 1 and 2
The blending materials shown in Table 1 were blended in the proportions shown in Table 1, and kneaded with a kneader and then with an open roll to prepare a sheet-like unvulcanized rubber composition. This unvulcanized rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a primary vulcanizate having a thickness of 2 mm. Further, this was heated in an air oven at 150 ° C. for 2 hours to obtain a secondary vulcanizate.

Evaluation test The secondary vulcanizate was evaluated for normal properties by a tensile test according to JIS K 6251, heat resistance according to JIS K 6257, and ozone resistance according to JIS K 6259.

The test results obtained are shown in Table 2.

In Table 1,
-Polyether rubber; epichlorohydrin / ethylene oxide copolymer,
Daiso "Epichromer C", chlorine content 25%
-Reinforcing agent: FEF carbon black, "Seast SO" manufactured by Tokai Carbon
・ Plasticizer: Di (butoxyethoxy) ethyl adipate ・ Lubricant: Sorbitan monostearate, “Splendor R300” manufactured by Kao Corporation
Acid acceptor I: highly active magnesium oxide, “MgO # 150” manufactured by Kyowa Chemical Co., Ltd.
Acid acceptor II: Synthetic hydrotalcite, “DHT-4A” manufactured by Kyowa Chemical Co., Ltd. Vulcanization accelerator: DBU (1,8-diazabicyclo [5,4,0] undecene-7)
Salt with phenolic resin, “P-152” manufactured by Daiso
Anti-aging agent I: diethyldithiocarbamate obtained in Reference Example 1
Reaction product of molybdenum compound Anti-aging agent II; dibenzyldithiocarbamate obtained in Reference Example 2 and
Reaction product of molybdenum compound Anti-aging agent III; compound represented by general formula (II),
"Adeka Sakura Lube 600" manufactured by Asahi Denka
Anti-aging agent IV: Diphenylamine-α-methylstyrene Delay agent: N- (cyclohexylthio) phthalimide Vulcanizing agent: 6-methylquinoxaline-2,3-dithiocarbonate

In Table 2, each test item is
M ₁₀₀ ; Tensile stress at 100% elongation as defined in the tensile test of JIS K6251 M ₃₀₀ ; Tensile stress at 300% elongation as defined in the tensile test of JIS K6251 T _b ; Tensile strength as defined in the tensile test of JIS K6251 E _b ; Elongation H _s defined in the tensile test of JIS K6251; Hardness defined in the hardness test of JIS K6253.

  The ozone test was performed under the conditions of static 50% elongation × 50 pphm × 40 ° C. Each symbol in Table 2 indicates the state of cracks in JIS K6259 as follows.

N-C: No crack A-1: Invisible to the naked eye, but there are few cracks that can be confirmed with a 10x magnifier B-1: Invisible to the naked eye, but there are many cracks that can be confirmed with a 10x magnifier C- 2: There are countless cracks that can be seen with the naked eye

The heat resistance is good, it is greater tensile strength T _b after the heat resistance test, for example 0.99 ° C., 7 or more in the heat resistance test of 70 hours, 0.99 ° C., is 3 or more in the heat resistance test of 168 hours Say that.

  From Table 2, in the epihalohydrin rubber, Examples 1 to 3 containing the reaction product in the first invention and the compound (II) in the second invention as an anti-aging agent are comparative examples containing no anti-aging agent. 1. Compared to Comparative Example 2 containing diphenylamine-α-methylstyrene, which is a known anti-aging agent, it has both excellent heat resistance and ozone resistance, and particularly has improved ozone resistance. I understand.

  The rubber composition for vulcanization of the present invention is constituted as described above, and the vulcanized product has both excellent heat resistance and ozone resistance. Therefore, it can be widely applied to the fields where synthetic rubber is usually used. For example, it is possible to obtain rubber products such as various fuel-based laminated hoses for automobiles, air-based laminated hoses, tubes, belts, diaphragms, seals, etc., and rubber products such as general industrial equipment / devices from the same composition. it can. Among these, the rubber vulcanizate according to the present invention can be suitably applied to rubber parts for automobiles, taking advantage of its excellent heat resistance and ozone resistance.

  Moreover, since the rubber composition for vulcanization | cure of this invention does not contain the organic nickel compound which is anxious about the influence on a human body, there also exists an advantage that the health hazard of a rubber product manufacturer and a rubber product user can be suppressed.

Claims (6)

(A) a polyether rubber, (b) a reaction product of a dithiocarbamic acid derivative represented by the general formula (I) and a molybdenum compound in an aqueous solvent, and (c) a vulcanizing agent. A rubber composition for vulcanization.

In the formula, R ¹ and R ² are the same or different and each represents an alkyl group, a cycloalkyl group, or an aralkyl group, and M represents a hydrogen atom or a metal atom. The rubber composition for vulcanization according to claim 1, wherein M is an alkali metal atom and the molybdenum compound is molybdenum pentachloride. A rubber composition for vulcanization comprising (a) a polyether rubber, (b) a compound represented by the general formula (II), and (c) a vulcanizing agent.

In the formula, R ¹ and R ² are the same or different and each represents an alkyl group, a cycloalkyl group, or an aralkyl group. The rubber composition for vulcanization according to any one of claims 1 to 3, wherein (a) the polyether rubber is an epihalohydrin rubber. A rubber vulcanizate obtained by vulcanizing the rubber composition for vulcanization according to any one of claims 1 to 4. A rubber product comprising the rubber vulcanizate according to claim 5.