JP2005220212A - Vulcanizing rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a vulcanizing rubber composition useful for applications including tire treads and industrial belts, and excellent in mechanical strength and vulcanization properties, and to provide a material compounding prescription for the composition. <P>SOLUTION: The vulcanizing rubber composition is obtained by compounding 100 pts. wt. of a sulfur-vulcanizable polymer with 0.1-50 pts. wt. of an ethylene-vinyl acetate copolymer and/or an ethylene-(meth)acrylic ester copolymer, 5-100 pts. wt. of silica and 0.1-20 pts. wt. of a vulcanizing agent, and optionally, appropriate amounts of rubber compounding ingredients including a vulcanization promoter, activator, inorganic filler, flexibilizer, plasticizer, silane coupling agent and anti-deteriorating agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vulcanized rubber composition excellent in mechanical strength and vulcanized rubber properties suitable for uses such as tire treads and industrial belts, and a raw material blended formulation thereof.

  In recent years, due to the growing interest in safety of automobiles, high performance has been required even for rubber compositions for tire treads. For this reason, silica has been increasingly used as a reinforcing filler in place of carbon black that has been generally used. However, since silica has silanol groups on its surface, particles tend to aggregate due to hydrogen bonding, causing poor dispersion during compounding into rubber, and expected mechanical strength and vulcanized rubber properties. Could not get.

  For this reason, a method of blending a silane coupling agent has been proposed, and a moderate improvement effect has been recognized, but the dispersion level of silica has not been sufficient. In addition, a method of using a water-treated silica has been proposed, but in this case, there is a problem that the rubber reinforcing effect is reduced (Patent Document 1).

JP-A-6-157825

  For this reason, the object of the present invention is to provide a compounding formula for obtaining a vulcanized rubber having sufficient mechanical strength and vulcanized rubber properties, which can be sufficiently dispersed in the rubber even when ordinary wet process silica is used. There is to do.

  That is, in the present invention, 0.1 to 50 parts by weight of an ethylene / vinyl acetate copolymer and / or an ethylene / (meth) acrylate copolymer, The present invention relates to a rubber composition for vulcanization comprising 100 parts by weight and 0.1 to 20 parts by weight of a vulcanizing agent. The present invention also relates to a vulcanized rubber composition obtained by vulcanizing the composition.

  ADVANTAGE OF THE INVENTION According to this invention, the vulcanized rubber composition excellent in mechanical strength, vulcanized rubber physical property, etc. and its raw material compounding prescription can be provided. The rubber composition for vulcanization according to the present invention and the composition after vulcanization obtained by vulcanizing the rubber composition are used for tires such as tire treads, under treads, carcass, sidewalls, bead portions, etc. It can be used for anti-vibration rubber, belts, hoses and other industrial applications. In particular, it can be suitably used for tire treads and industrial belts.

The vulcanizable polymer used in the present invention is a polymer that exhibits rubber-like elasticity by sulfur vulcanization, and a typical one is a diene polymer or copolymer. More specifically, polybutadiene rubber (BR), styrene / butadiene copolymer rubber (SBR), acrylonitrile / butadiene copolymer rubber (NBR), natural rubber (NR), polyisoprene rubber (IR), butyl rubber (IIR), Mention may be made of chloroprene rubber (CR), ethylene / propylene / diene copolymer rubber (EPDM), norbornene copolymer (PNR), or a mixture thereof. Among these, it is preferable to use a styrene / butadiene copolymer rubber or to use this in combination with another diene polymer or copolymer. A suitable styrene-butadiene copolymer rubber has a styrene content of 5 to 45% by weight, preferably 10 to 30% by weight in view of mechanical strength and vulcanized physical properties, and optionally other monomers such as acrylonitrile. It may be copolymerized. In consideration of processability, mechanical strength, heat resistance, etc., it is preferable to use a Mooney viscosity (ML _{1 + 4} (100 ° C.)) measured at 100 ° C. of 20 to 200, particularly 25 to 180.

  In the present invention, an ethylene / vinyl acetate copolymer and / or an ethylene / (meth) acrylate copolymer are used together with a sulfur vulcanizable polymer. The ethylene / vinyl acetate copolymer is a copolymer of two or more consisting of ethylene and vinyl acetate and optionally other monomers, and the ethylene content is usually from 50 to 99% by weight, preferably from 55 to 99% by weight. 95 wt%, more preferably 60-90 wt%, vinyl acetate content is usually 1-50 wt%, preferably 5-45 wt%, more preferably 10-40 wt%, other monomers are The copolymer is usually in a proportion of 0 to 40% by weight, preferably 0 to 30% by weight, more preferably 0 to 20% by weight. Other monomers that may be optionally copolymerized in the ethylene / vinyl acetate copolymer include (meth) acrylic acid esters which will be described later as constituents of the ethylene / (meth) acrylic acid ester copolymers. , Unsaturated carboxylic acid esters such as dimethyl maleate and diethyl maleate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, halogen-containing unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride, other vinyl ethers and maleimides , Vinyl silane compounds, carbon monoxide and the like.

  The ethylene / (meth) acrylic acid ester copolymer is a copolymer of two or more consisting of ethylene and (meth) acrylic acid ester and optionally other monomers, and the ethylene content is usually 50-99 wt%, preferably 55-95 wt%, more preferably 60-90 wt%, (meth) acrylic acid ester content is usually 1-50 wt%, preferably 5-45 wt%, more preferably Is a copolymer having a ratio of 10 to 40% by weight, and other monomers are usually 0 to 40% by weight, preferably 0 to 30% by weight, and more preferably 0 to 20% by weight. Here, (meth) acrylic acid ester is acrylic acid ester or methacrylic acid ester, specifically, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, isobutyl acrylate, n-acrylate. -Butyl, t-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, isobutyl methacrylate, n-methacrylate A butyl etc. can be illustrated. Other monomers include vinyl esters such as vinyl acetate and vinyl propionate, other unsaturated carboxylic esters such as dimethyl maleate and diethyl maleate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, and vinyl chloride. And halogen-containing unsaturated monomers such as vinylidene chloride and vinyl fluoride, vinyl ethers, maleimides, vinyl silane compounds, carbon monoxide, and the like.

  As these ethylene / vinyl acetate copolymer and ethylene / (meth) acrylic acid ester copolymer, the melt flow rate at 190 ° C. and 2160 g load measured according to JIS K7210-1999 is 0.1 to 3000 g / 10 min. Particularly preferred is 1 to 2000 g / 10 min, especially 10 to 100 g / 10 min. Such an ethylene / vinyl acetate copolymer or an ethylene / (meth) acrylic acid ester copolymer can be produced by radical copolymerization under high temperature and high pressure.

  In the rubber composition for vulcanization of the present invention, the above-described sulfur vulcanizable polymer is added to silica and vulcanized together with an ethylene / vinyl acetate copolymer and / or an ethylene / (meth) acrylate copolymer. A sulfurizing agent is blended. Various types of silica such as wet method silica, dry method silica, and synthetic silicate-based silica can be used as the silica, but it is particularly preferable to use wet method silica having an excellent reinforcing effect. Further, as these silicas, those that have been partially water-treated with an organic silicon compound may be used, or those that are combined with carbon black may be used. Silica having a particle size of 5 to 30 μm and a bulk specific gravity of 30 to 500 g / L is preferable.

  The vulcanizing agent used in the present invention is a vulcanizing agent capable of sulfur vulcanization, and examples thereof include sulfur or sulfur-containing compounds such as sulfur chloride, sulfur dichloride, dithiomorpholine, thiurams, and dithiocarbamate. it can.

  In the rubber composition for vulcanization | cure of this invention, the other rubber compounding agent mix | blended in the rubber composition for general vulcanization | cure can be arbitrarily mix | blended as needed. Examples of such rubber compounding agents include fillers other than silica, vulcanization accelerators, activators, vulcanization accelerators, vulcanization retarders (scorch inhibitors), other fillers, plasticizers, softeners. , Extender oil, anti-aging agent, ultraviolet absorber, ozone degradation inhibitor, silane coupling agent, tackifier and the like.

  Specific examples of vulcanization accelerators include guanidines such as diphenylguanidine, di-o-tolylguanidine, o-tolylbiguanide, dicatechol borate di-o-tolylguanidine salt; 2-mercaptobenzothiasol, dibenzothia Thiazoles such as dil disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (4′-morpholinodithio) benzothiazole; N-cyclohexyl-2-benzothiazylsulfenamide, N, N-dicyclohexyl-2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N, N-diisopropyl-2-benzothiazylsulfenamide, Nt-butyl- 2-benzothiazylsulfe Sulfenamides such as amides; thioureas such as thiocarbanilide, ethylenethiourea (2-mercaptoimidazoline), diethylthiourea, dibutylthiourea, trimethylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram monosulfide, Thiurams such as tetrabutylthiuram monosulfide, N, N′-dimethyl-N, N′-diphenylthiuram disulfide, pentamethylenethiuram tetrasulfide; dithiocarbamic acid such as zinc dimethylcarbamate, zinc diethylcarbamate, zinc dibutylcarbamate Salt, di-n-butylamine, dicyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, dibenzylamine, etc. Rukiruamin compounds can be mentioned. Examples of the crosslinking aid include polyunsaturated compounds such as ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, N, N′-m-phenylene dimaleimide, triallyl isocyanurate, and zinc methacrylate. it can.

  Examples of the activator include zinc oxide, cadmium oxide, magnesium oxide, lead oxide, stearic acid, zinc stearate, diethylene glycol, and polyethylene glycol.

  Examples of the vulcanization retarder include phthalic anhydride, salicylic acid, benzoic acid, N-nitrosodiphenylamine, N-cyclohexylthiophthalimide and the like.

  Examples of fillers that can be used in combination with silica include carbon black, composites thereof, talc, calcium carbonate, clay, calcined clay, aluminum hydroxide, barium sulfate, and whiskerdelite. A surface-treated product can also be used for these. These are known to be different in production method, average particle diameter, surface area, oil absorption amount, etc., any of which can be used. For example, various types of carbon black such as SAF, ISAF, ISAF-HS, HAF, HAF-HS, FEF, GPF, and SRF can be used.

  Plasticizers as rubber compounding agents include: dimethyl phthalate, dibutyl phthalate, diisobutyl phthalate, di (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisononyl phthalate, dibutyl adipate, diadipate (2-ethylhexyl), isodecyl adipate, di (2-ethylhexyl) azelate, di-n-butyl sebacate, di (2-ethylhexyl) sebacate, tri-n-octyl trimellitic acid, triisodecyl trimellitic acid, Examples include various esters such as tetra (2-ethylhexyl) pyromellitic acid, tributyl phosphate, tri (2-ethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, and triphenyl phosphate.

  Examples of the softening agent and extension oil include aroma-based process oil, naphthenic process oil, and paraffin-based process oil.

  Anti-aging agents, ultraviolet absorbers and the like include phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p-toluenesulfonylamido) diphenylamine, 4,4 ′-(α, α′-dimethylbenzyl) diphenylamine, 4,4'-octyldiphenylamine, octylated diphenylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N- (1,3-dimethylbutyl ) Amines such as -N'-phenyl-p-phenylenediamine; 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1,2- Quinoline series such as dihydroquinoline; 2,6-di-t-butyl-4-methylphenol, styrenated phenol 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy) Benzyl) benzene, 4,4′-thiobis (6-tert-butyl-3-methylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), n-octadecyl-3- (4 ′ Phenols such as -hydroxy-3 ', 5'-di-t-butylphenyl) propionate, tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyfekyl) propionate] methane Tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-t-butyl-4) Phosphorus series such as -methylphenyl phosphite); sulfur series such as dilauroyl thiodipropionate, distearyl thiodipropionate, pentaerythritol tetrakis (β-lauryl thiopropionate); 2-mercaptobenzimidazole, 2- Benzimidazoles such as mercaptomethylbenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, etc .; other nickel dimethyldithiocarbamate, nickel dibutyldithiocarbamate, 1,3-bis (dimethylaminopropyl) -2-thiourea, tributylthio Various compounds such as urea can be exemplified. Waxes can be used as the ozone deterioration preventing agent.

  As the silane coupling agent, bis (3-triethoxysilylpropyl) sulfane, bis (3-triethoxysilylpropyl) polysulfide, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ -Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, bis (3-trimethylsilylpropyl) tetrasulfide, 3-trimethoxysilylpropyl-N, N-dimethylcarbamoyl tetrasulfide, Examples include 2-benzothiazyl-3-trimethoxysilylpropyl tetrasulfide.

  Of course, these rubber compounding agents can be used in combination of two or more of the same type or two or more of the same type.

  In the vulcanized rubber composition of the present invention, ethylene / vinyl acetate copolymer and / or ethylene / (meth) acrylic acid ester copolymer is used with respect to 100 parts by weight of the vulcanizable polymer, depending on the purpose of use. The coalescence is 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, more preferably 1 to 20 parts by weight, silica 5 to 100 parts by weight, preferably 10 to 80 parts by weight, and the vulcanizing agent 0 .1 to 20 parts by weight, preferably 0.5 to 10 parts by weight. Addition of ethylene / vinyl acetate copolymer and / or ethylene / (meth) acrylate copolymer improves dispersibility of silica and improves mechanical strength and vulcanization properties. If it is added too much, the rubber properties will be adversely affected. In addition, the blending of silica improves the mechanical strength and vulcanized physical properties. However, if the blending is too large, the workability is impaired, so the blending ratio is as described above. Furthermore, the amount of the vulcanizing agent used varies depending on the type of vulcanizable polymer, the type of vulcanizing agent, other rubber compounding agents and the amount to be added arbitrarily, and the like, but is used in the above ratio. Further, it is effective to mix an appropriate amount of the silane coupling agent. For example, it is preferable to mix 1 to 20 parts by weight, particularly 5 to 15 parts by weight of the silane coupling agent per 100 parts by weight of silica.

  The rubber composition for vulcanization of the present invention can be prepared according to a general method for producing vulcanized rubber. For example, using a kneader generally used in the production of vulcanized rubber, such as a Banbury mixer, (pressure) kneader, open roll, etc., a sulfur vulcanizable polymer, ethylene / vinyl acetate copolymer and / or Ethylene / (meth) acrylic acid ester copolymer and silica, and other fillers as described above, activators, plasticizers, softeners, extender oils, anti-aging agents, UV absorbers, ozone degradation inhibitors, silanes A general rubber compounding agent such as a coupling agent is mixed to prepare an A kneading compound.

  Next, sulfur or a sulfur-containing compound as described above as a vulcanizing agent is blended into the kneading compound A alone or in combination of two or more, and as the vulcanization accelerator, guanidines, thiazoles as described above, A sulfenamide, a thiourea, a thiuram, a dithiocarbamate, or the like is blended alone or in combination of two or more. Further, if necessary, a vulcanization retarder as described above is blended, molded into a predetermined shape and subjected to thermal vulcanization, and further subjected to secondary vulcanization as required to obtain a desired vulcanized rubber composition. Can be obtained. For example, when used for a tire tread, the rubber composition for vulcanization of the present invention is extruded into a tread member in an unvulcanized state, and pasted and molded by a usual method on a tire molding machine. Is formed. A tire with a tread made of the vulcanized rubber composition of the present invention is produced by heating and pressing the green tire in a vulcanizer.

EXAMPLES Next, although this invention is demonstrated in detail using an Example, this invention is not restrained by the following Examples. In addition, the raw material and the physical-property evaluation method which were used by the Example and the comparative example are as follows.
(1) Used raw materials The materials shown in Table 1 were used.

ＭＦＲ：ＪＩＳ Ｋ７２１０−１９９９（１９０℃、２１６０ｇ荷重）

MFR: JIS K7210-1999 (190 ° C., 2160 g load)

(2) Physical property evaluation method (2-1) Preparation of compound A kneading was made by a conventional method using a BB-4 Banbury mixer manufactured by Kobe Steel Co., Ltd. with a filling rate of 70%. B kneading used for evaluation was prepared by kneading a vulcanizing agent and a vulcanization accelerator with a 6-inch roll at 40 ° C.

(2-2) Unvulcanized physical properties Using a torsional vibration type flat plate die vulcanization tester, measurement was performed at 160 ° C. for 60 minutes and at an amplitude of 0.5 °.

(2-3) Vulcanized Physical Properties Samples obtained by press vulcanizing the B-kneaded compound prepared by the procedure of (2-1) under conditions of primary vulcanization at 160 ° C. for 20 minutes were evaluated by the following tests.
(A) Tensile test: Measured according to JIS K6251.
(B) Hardness test: Measured according to JIS K6253.
(C) Compression set test: Measured under conditions of 70 ° C. and 70 hours in accordance with JIS K6262.
(D) Aging test: Measured under conditions of 70 ° C. and 70 hours in accordance with JIS K6257.

[Example 1]
A kneaded compound was prepared using 100 parts by weight of SBR shown in Table 1, 5 parts by weight of EVA, 50 parts by weight of silica, 2 parts by weight of stearic acid, 3 parts by weight of diethylene glycol and 3 parts by weight of ZnO, and then 1.4 parts by weight of sulfur, A B-kneaded compound was obtained by blending 1.7 parts by weight of CBS and 2 parts by weight of DPG. The unvulcanized physical properties and vulcanized physical properties were measured. The blending composition is shown in Table 2, and the physical property evaluation results of the compound are shown in Table 3.

[Example 2]
In Example 1, it replaced with 5 weight part of EVA, and carried out similarly to Example 1 except having used 5 weight part of EEA. The blending composition is shown in Table 2, and the physical property evaluation results of the compound are shown in Table 3.

[Comparative Example 1]
In Example 1, it carried out like Example 1 except not having mix | blended EVA. The blending composition is shown in Table 2, and the physical property evaluation results of the compound are shown in Table 3.

  As is clear from the comparison of Examples 1 and 2 and Comparative Example 1 in Table 3, it can be seen that mechanical strength, compression set, heat aging resistance and the like are improved by blending EVA and EEA.

Claims (8)

  0.1 to 50 parts by weight of ethylene / vinyl acetate copolymer and / or ethylene / (meth) acrylic acid ester copolymer, 5 to 100 parts by weight of silica and vulcanized to 100 parts by weight of the sulfur vulcanizable polymer. A rubber composition for vulcanization comprising 0.1 to 20 parts by weight of a sulfurizing agent.   The rubber composition for vulcanization according to claim 1, further comprising a rubber compounding agent.   The rubber composition for vulcanization according to claim 2, wherein the rubber compounding agent is selected from a filler, a vulcanization accelerator, an activator, a softener, a plasticizer, a silane coupling agent and an anti-aging agent.   4. The rubber composition for vulcanization according to claim 1, wherein the sulfur-capable polymer is a diene polymer or copolymer.   The diene polymer or copolymer is a polybutadiene rubber, styrene / butadiene copolymer rubber, acrylonitrile / butadiene copolymer rubber, natural rubber, polyisoprene rubber, butyl rubber, chloroprene rubber, ethylene / propylene / diene copolymer rubber or norbornene copolymer. The rubber composition for vulcanization according to claim 4, which is a polymer selected from polymer rubber.   2. The ethylene / vinyl acetate copolymer has a vinyl acetate content of 1 to 50% by weight and a melt flow rate at 190 ° C. and a load of 2160 g measured according to JIS K7210-1999 of 0.1 to 3000 g / 10 min. The rubber composition for vulcanization | cure of -5.   The ethylene / (meth) acrylic acid ester copolymer has a (meth) acrylic acid ester content of 1 to 50% by weight, a melt flow rate at 190 ° C. and a load of 2160 g measured according to JIS K7210-1999 is 0.1 to 3000 g / 10. The rubber composition for vulcanization according to claim 1, wherein the rubber composition is for vulcanization. A vulcanized rubber composition obtained by vulcanizing the rubber composition for vulcanization according to claim 1.