JP2007031569A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which retains the merits of a conventional improved polybutadiene rubber and is excellent in properties such as hardness and elasticity (especially elasticity at a low elongation). <P>SOLUTION: The rubber composition comprises (A) 10 to 80 wt.% natural rubber and/or synthetic diene rubber, (B) 5 to 60 wt.% reinforced polybutadiene rubber component obtained by a step of adding a cis-1,4 polymerization catalyst obtained from an organoaluminum compound and a soluble cobalt compound to a mixture having a controlled water concentration and mainly consisting of 1,3-butadiene and a hydrocarbon-type organic solvent and effecting the cis-1,4 polymerization of the 1,3-butadiene, and (C) 5 to 70 wt.% fiber-reinforced rubber component composed of a matrix comprising a vulcanizable elastomer and a thermoplastic polyamide dispersed in the matrix in the form of microfibers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition having a high hardness and a high elastic modulus which is a novel rubber and is suitable for members such as industrial automobile tires.

  In recent years, in the automobile industry, from the viewpoint of resource saving and energy saving, improvement of rubber hardness, elasticity, wear resistance, mechanical properties, and dynamic characteristics (heat generation characteristics and tan δ) has been studied. As such a rubber, an improved polybutadiene rubber in which syndiotactic-1,2-polybutadiene (SPBD) is dispersed in a matrix of high cis-1,4-polybutadiene (hereinafter “high cis polybutadiene”) has been proposed ( Japanese Patent Publication No.49-17666 (Patent Document 1)). Since this polybutadiene rubber has a structure in which SPBD is dispersed in a fiber form in a high cis polybutadiene matrix, it has higher hardness and elasticity than conventional rubbers such as high cis polybutadiene plain rubber. It has the feature of excellent bending crack growth.

  For this reason, various tire members using this improved polybutadiene have been proposed. For example, there are an example used for a tread (Japanese Patent Publication No. 63-1355 (Patent Document 2)) and an example used for a sidewall (Japanese Patent Publication No. 55-17059 (Patent Document 3)).

  Japanese Patent No. 2763480 (Patent Document 4) discloses an industrial truck tire using a high-hardness rubber composition containing a diene rubber component containing a syndio crystal, a filler, and sulfur as a base portion. ing. JP-A-6-192479 (Patent Document 5) contains a masterbatch rubber obtained by chemically bonding a thermoplastic polyamide short fiber and a diene rubber, a diene rubber, carbon black, and a novolac modified phenolic resin. A rubber composition is disclosed.

  However, forklift tires, solid tires, or bead rubbers such as bead fillers and chafers are rubbers that have higher elastic modulus and hardness at low elongation from the viewpoint of running stability, shape maintenance, and low loss. A composition was desired.

  Generally, radial cords also use steel cords in terms of high-speed durability and high-speed maneuverability. When a steel cord is used, a very large strain concentration tends to occur in the rubber near the steel cord when the tire is running. Accordingly, the steel cord rubber is required to have a high elastic modulus and excellent adhesion to metal. Also in radial tires and bias tires using organic fiber cords, the rubber for cords preferably has a high elastic modulus from the viewpoint of durability.

  Various methods have been tried to obtain a high elastic modulus rubber. A method of blending a large amount of carbon black is not preferable because the rubber is not well-organized in the processing step, the power load is increased during kneading or extrusion, and the blend ML becomes large, which is difficult during extrusion. The method of blending a large amount of sulfur has drawbacks such as blooming of sulfur and increased crack growth due to increased crosslinking density. Addition of the thermosetting resin tends to cause poor dispersion because the thermosetting resin has low compatibility with natural rubber or diene rubber generally used as a cord coating rubber, and is inferior in crack resistance. Further, conventionally known tire cord coating rubber compositions have a small green strength and are required to have a larger green strength from the viewpoint of moldability.

  Japanese Patent Application Laid-Open No. 2002-47376 (Patent Document 6) includes (A) a specific natural rubber and / or diene-based synthetic rubber component of 10 to 80% by weight, (B) a specific reinforced polybutadiene rubber component of 5 to 60% by weight, and (C) A rubber composition comprising 5 to 70% by weight of a specific fiber-reinforced rubber component, wherein (B) component is mainly syndiotactic-1,2-polybutadiene having a reduced specific viscosity of 0.5 to 4. A reinforced polybutadiene rubber comprising 1 to 30% by weight of a boiling n-hexane insoluble component as a component and 70 to 99% by weight of a boiling n-hexane soluble component mainly composed of high cis-1,4-polybutadiene, C) A thermoplastic polymer having an amide group in the main chain is dispersed in a fine fiber form in a matrix composed of an elastomer that can be vulcanized, and the thermoplastic polymer is bonded to the matrix. That a fiber-reinforced rubber, polybutadiene rubber is disclosed which is excellent in properties such as hardness and elasticity (especially elasticity at low elongation reduction).

Japanese Patent Publication No.49-17666 Japanese Patent Publication No. 63-1355 Japanese Patent Publication No.55-17059 Japanese Patent No. 2762480 JP-A-6-192479 JP 2002-47376 A

  An object of the present invention is to provide a rubber composition excellent in properties such as hardness and elasticity (especially elasticity at low elongation) while retaining the advantages of the conventional improved polybutadiene rubber.

The present invention includes (A) natural rubber and / or diene synthetic rubber component 10 to 80% by weight, (B) reinforced polybutadiene rubber component 5 to 60% by weight, and (C) fiber reinforced rubber component 5 to 70% by weight. It is related with the rubber composition in which this (B) component and (C) component have the following characteristics.
Component (B): (a) (1) A cis-obtained from an organoaluminum compound and a soluble cobalt compound in a mixture of water-adjusted 1,3-butadiene and hydrocarbon organic solvent as main components A step of adding 1,4 polymerization catalyst to polymerize 1,3-butadiene in cis-1,4 polymerization, and then (2) soluble cobalt compound and general formula AlR ₃ (where R is 1,3-butadiene is polymerized in the presence of a catalyst obtained from an organoaluminum compound represented by an alkyl group having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl group and carbon disulfide. Vinyl cis-polybutadiene obtained from the process, and
(B) A reinforced polybutadiene rubber component obtained by adding the cis-1,4 polymerization catalyst and mixing the cis-polybutadiene obtained by cis-1,4 polymerization of 1,3-butadiene.
(C) component: (c-1) a fiber reinforced rubber in which a thermoplastic polyamide is dispersed in a fine fiber form in a matrix composed of a vulcanizable elastomer, and the thermoplastic polyamide is bonded to the matrix; (C-2) A fiber-reinforced rubber composition obtained by blending natural rubber and / or diene-based synthetic rubber and (c-3) carbon black.

  The present invention also relates to the rubber composition described above, wherein the polymerization temperature in the step (1) of polymerizing 1,3-butadiene of (a) (2) is -5 to 50 ° C.

  The present invention relates to the rubber composition as described above, wherein the vinyl cis-polybutadiene obtained in (a) has a boiling n-hexane insoluble fraction (HI) of 10 to 60% by weight.

  According to the present invention, it is possible to provide a rubber composition excellent in high hardness, high elastic modulus, low loss, and low compressive strain.

Examples of the component (A) of the rubber composition of the present invention include natural rubber and diene synthetic rubber. Specific examples include diene rubbers such as natural rubber, high cis polybutadiene rubber, low cis polybutadiene rubber, styrene-butadiene rubber, isoprene rubber, and acrylonitrile-butadiene rubber. Among these, natural rubber is preferable. In addition, those obtained by modifying these rubbers with epoxy modification, silane modification, male modification and the like can also be used.

The component (B) of the rubber composition of the present invention comprises (a) (1) a mixture of 1,3-butadiene and a hydrocarbon-based organic solvent in which the water concentration is adjusted, and an organoaluminum compound. A step of adding a cis-1,4 polymerization catalyst obtained from a soluble cobalt compound to polymerize 1,3-butadiene in cis-1,4, and subsequently (2) a soluble cobalt compound and a general compound in the resulting polymerization reaction mixture. In the presence of a catalyst obtained from an organoaluminum compound represented by the formula AlR ₃ (wherein R is an alkyl group having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl group) and carbon disulfide, -Vinyl cis-polybutadiene obtained from the process of 1,2-polymerizing butadiene, and
(B) It is produced by adding the cis-1,4 polymerization catalyst and mixing cis-polybutadiene obtained in the step of cis-1,4 polymerization of 1,3-butadiene.

(A) Production of vinyl cis-polybutadiene Hydrocarbon solvents include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as n-hexane, butane, heptane and pentane, cyclopentane and cyclohexane. Alicyclic hydrocarbons such as olefin compounds, olefinic hydrocarbons such as cis-2-butene and trans-2-butene, hydrocarbon solvents such as mineral spirits, solvent naphtha and kerosene, and halogens such as methylene chloride. And hydrocarbon-based solvents. 1,3-butadiene monomer itself may be used as a polymerization solvent.

  Among these, toluene, cyclohexane, or a mixture of cis-2-butene and trans-2-butene is preferably used.

  Next, the concentration of water in the mixed medium obtained by mixing 1,3-butadiene and the solvent is adjusted. The water content is preferably in the range of 0.1 to 1.0 mol, particularly preferably 0.2 to 1.0 mol, per mol of organoaluminum chloride in the medium. Outside this range, the catalytic activity is decreased, the cis 1,4 structure content is decreased, the molecular weight is abnormally decreased or increased, and the generation of gel during polymerization cannot be suppressed. This is not preferable because gel adheres to the tank and the continuous polymerization time cannot be extended. A known method can be applied as a method of adjusting the moisture concentration. A method of adding and dispersing through a porous filter medium (Japanese Patent Laid-Open No. 4-85304) is also effective.

  An organoaluminum compound is added to the solution obtained by adjusting the water concentration. Examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum sesquibromide, alkylaluminum sesquibromide, and alkylaluminum dichloride.

  Specific examples of the compound include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum.

In addition, dialkylaluminum chlorides such as dimethylaluminum chloride and diethylaluminum chloride, organoaluminum halogen compounds such as sesquiethylaluminum chloride and ethylaluminum dichloride, hydrogenated organics such as diethylaluminum hydride, diisobutylaluminum hydride and sesquiethylaluminum hydride Aluminum compounds are also included. Two or more of these organoaluminum compounds can be used in combination.
As a specific example of the amount of the organoaluminum compound used, 0.1 mmol or more, particularly 0.5 to 50 mmol is preferable per 1 mol of the total amount of 1,3-butadiene.

  Next, a soluble cobalt compound is added to the mixed medium to which the organoaluminum compound is added, and cis 1,4 polymerization is performed. Soluble cobalt compounds are those that are soluble in an inert medium or liquid 1,3-butadiene containing a hydrocarbon solvent as a main component, or can be uniformly dispersed, such as cobalt (II) acetylacetonate, cobalt (III) Cobalt β-diketone complexes such as acetylacetonate, cobalt β-keto acid ester complexes such as cobalt acetoacetate ethyl ester complex, organic compounds having 6 or more carbon atoms such as cobalt octoate, cobalt naphthenate, and cobalt benzoate Examples thereof include cobalt halides such as cobalt salts of carboxylic acids, cobalt chloride pyridine complexes, and cobalt chloride ethyl alcohol complexes. The amount of the soluble cobalt compound used is preferably 0.001 mmol or more, more preferably 0.005 mmol or more, per mol of 1,3-butadiene. The molar ratio (Al / Co) of the organoaluminum chloride to the soluble cobalt compound is 10 or more, and particularly preferably 50 or more. In addition to soluble cobalt compounds, nickel organic carboxylates, nickel organic complexes, organolithium compounds, neodymium organic carboxylates, and neodymium organic complexes can also be used.

  The temperature at which cis 1,4 polymerization is carried out is such that 1,3-butadiene is cis 1,4 polymerized in a temperature range of more than 0 ° C. to 100 ° C., preferably 10 to 100 ° C., more preferably 20 to 100 ° C. The polymerization time (average residence time) is preferably in the range of 10 minutes to 2 hours. The cis 1,4 polymerization is preferably performed so that the polymer concentration after the cis 1,4 polymerization is 5 to 26% by weight. The polymerization tank is performed by connecting one tank or two or more tanks. The polymerization is carried out by stirring and mixing the solution in a polymerization tank (polymerizer). As a polymerization tank used for the polymerization, a polymerization tank equipped with a high-viscosity liquid stirring apparatus, for example, an apparatus described in JP-B-40-2645 can be used.

  Known molecular weight regulators in the cis 1,4 polymerization of the present invention, for example, non-conjugated dienes such as cyclooctadiene, allene, and methylallene (1,2-butadiene), or α- such as ethylene, propylene, and butene-1. Olefins can be used. In order to further suppress the formation of gel during polymerization, a known gelation inhibitor can be used. It is preferable that the cis 1,4-structure content is generally 90% or more, particularly 95% or more.

Mooney viscosity (ML _{1 + 4} , 100 ° C., hereinafter abbreviated as ML) 10 to 130, particularly 15 to 80 is preferable. Contains substantially no gel content.

  The 5% toluene solution viscosity (Tcp) is preferably 150 to 250.

1,3-butadiene may or may not be added to the cis 1,4 polymer obtained as described above. Then, an organoaluminum compound represented by the general formula AlR ₃ , carbon disulfide, and, if necessary, the above-mentioned soluble cobalt compound are added to produce 1,3-butadiene by 1,2 polymerization to produce vinyl cis polybutadiene rubber (VCR). . Preferable examples of the organoaluminum compound represented by the general formula AlR ₃ include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and triphenylaluminum. The organoaluminum compound is at least 0.1 mmol, especially 0.5 to 50 mmol, per mole of 1,3-butadiene. The carbon disulfide is not particularly limited, but is preferably one that does not contain moisture. The concentration of carbon disulfide is 20 mmol / L or less, particularly preferably 0.01 to 10 mmol / L. A known phenyl isothiocyanate or xanthate compound may be used as an alternative to carbon disulfide.

  The temperature for the 1,2 polymerization is preferably from -5 to 100 ° C, particularly preferably from -5 to 50 ° C. 1 to 50 parts by weight, preferably 1 to 20 parts by weight of 1,3-butadiene per 100 parts by weight of the cis polymerization solution is added to the polymerization system for the 1,2 polymerization. The yield of 1,2-polybutadiene can be increased. The polymerization time (average residence time) is preferably in the range of 10 minutes to 2 hours. The 1,2 polymerization is preferably performed so that the polymer concentration after the 1,2 polymerization is 9 to 29% by weight. The polymerization tank is performed by connecting one tank or two or more tanks. The polymerization is carried out by stirring and mixing the polymerization solution in a polymerization tank (polymerizer). As a polymerization tank used for 1,2 polymerization, a higher viscosity is obtained during the 1,2 polymerization, and the polymer tends to adhere to it. Can be used.

  The proportion (HI) of boiling n-hexane insoluble matter in the obtained vinyl cis-polybutadiene is preferably 10 to 60% by weight, particularly preferably 30 to 40%, particularly preferably 30 to 50% by weight.

  After the polymerization reaction reaches a predetermined polymerization rate, a known anti-aging agent can be added according to a conventional method. Typical antioxidants include phenolic 2,6-di-t-butyl-p-cresol (BHT), phosphorous trinonylphenyl phosphite (TNP), sulfur-based 4.6-bis (octylthio). Methyl) -o-cresol, dilauryl-3,3′-thiodipropionate (TPL) and the like. It may be used alone or in combination of two or more, and the addition of the antioxidant is 0.001 to 5 parts by weight with respect to 100 parts by weight of the VCR. Next, a polymerization terminator is added to the polymerization system and stopped. For example, after the polymerization reaction is completed, the polymerization solution is supplied to a polymerization stop tank, and a large amount of a polar solvent such as methanol or ethanol or water or a polar solvent such as water, inorganic acid such as hydrochloric acid or sulfuric acid, acetic acid, benzoic acid, etc. This is a method known per se, such as a method of introducing an organic acid or hydrogen chloride gas into the polymerization solution. Subsequently, vinyl cis polybutadiene (hereinafter abbreviated as VCR) produced according to a usual method is separated, washed and dried.

The proportion of boiling n-hexane insoluble matter (HI) in the vinyl cis-polybutadiene thus obtained is preferably 10 to 60% by weight, particularly preferably 30 to 50% by weight.
The boiling n-hexane soluble component is cis 1,4-polybutadiene having a microstructure of 90% or more.

  The VCR thus obtained was separated from the remaining unreacted 1,3-butadiene, inert medium and carbon disulfide-containing mixture by distillation as 1,3-butadiene, an inert medium. On the other hand, carbon disulfide is separated and removed by adsorption separation treatment of carbon disulfide or separation treatment of carbon disulfide adduct, and 1,3-butadiene and an inert medium substantially free of carbon disulfide are recovered. To do. Further, carbon disulfide is substantially contained by recovering three components from the mixture by distillation and separating and removing carbon disulfide from the distillation by the adsorption separation or carbon disulfide deposit separation treatment. Unrecovered 1,3-butadiene and inert media can also be recovered. The carbon disulfide recovered as described above and the inert medium are used by mixing freshly replenished 1,3-butadiene.

  When continuously operated by the method according to the present invention, the operability of catalyst components is excellent, and a VCR can be produced continuously for a long time with high catalyst efficiency and industrially advantageously. In particular, it can be continuously produced industrially advantageously at a high conversion without adhering to the inner wall of the polymerization tank, the stirring blade, and other parts where the stirring is slow.

(B) Production of cis-polybutadiene In the same manner as the production method of (a) and (1) above, that is, the step of adding cis-1,4 polymerization catalyst to polymerize 1,3-butadiene in cis-1,4. Can be manufactured.

  The obtained cis-polybutadiene preferably has a cis 1,4-structure content of generally 90% or more, particularly 95% or more.

Mooney viscosity (ML _{1 + 4} , 100 ° C., hereinafter abbreviated as ML) 10 to 130, particularly 15 to 80 is preferable. Contains substantially no gel content.

  The 5% toluene solution viscosity (Tcp) is preferably 30 to 250.

The ratio of (A) and (B) in the vinyl cis-polybutadiene rubber obtained by solution-mixing (a) vinyl cis-polybutadiene and (b) cis-polybutadiene is (A) / (B) = 10 It is preferable that it is 50 weight% / 90-50 weight%.

  Component (C) of the rubber composition of the present invention comprises (c-1) a thermoplastic polyamide dispersed in a fine fiber form in a matrix made of a vulcanizable elastomer, and the thermoplastic polyamide is a matrix. It is a fiber reinforced rubber composition comprising a bonded fiber reinforced rubber, (c-2) natural rubber and / or diene synthetic rubber and (c-3) carbon black. Examples of the vulcanizable elastomer forming the matrix of component (c-1) include natural rubber, polyisoprene, polybutadiene, styrene-butadiene rubber, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, and acrylonitrile-butadiene rubber. Can do. Among these, natural rubber is preferable. Also, those obtained by modifying these rubbers with epoxy, silane-modified, or maleated may be used.

  The matrix may contain a polyolefin. The polyolefin preferably has a melting point of 80 to 250 ° C., and preferably has a Vicat softening point of 50 ° C. or more, particularly a Vicat softening point of 50 to 200 ° C.

  Examples of such polyolefins include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, olefins having 2 to 8 carbon atoms, and aromatic vinyl compounds such as styrene, chlorostyrene, α-methylstyrene, and the like. A copolymer of olefins having 2 to 8 carbon atoms and vinyl acetate, acrylic acid or esters thereof, methacrylic acid or esters thereof, copolymers of olefins having 2 to 8 carbon atoms and vinylsilane compounds, etc. A polymer is mentioned.

  Specifically, for example, high density polyethylene, low density polyethylene, polypropylene, ethylene / propylene block or random copolymer, linear low density polyethylene, poly-4-methylpentene-1, polybutene-1, polyhexene-1, etc. Polyolefins, copolymers of ethylene and vinyl acetate, copolymers of acrylic acid, methyl acrylate, etc., copolymers of ethylene and vinyltrimethoxysilane, vinyltriethoxysilane, etc., ethylene or propylene and styrene copolymers Etc. Further, halogenated polyolefins such as chlorinated polyethylene are also preferably used. These polyolefins may be used alone or in combination of two or more.

  The thermoplastic polyamide dispersed in the form of fine fibers in the matrix and bonded to the matrix is a thermoplastic polymer having an amide group in the main chain. Those modified with a silane coupling agent are preferred.

  Examples of the thermoplastic polymer having an amide group in the main chain include thermoplastic polyamide and urea resin. A melting point of 135 ° C to 350 ° C is preferable, and 150 ° C to 300 ° C is particularly preferable.

  The thermoplastic polyamides include nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 610, nylon 612, nylon 46, nylon 11, nylon 12, nylon MXD6, xylylenediamine and adipic acid, pimelic acid, and spellin. Polycondensates of acid, azelaic acid, sebacic acid, etc., polycondensation of terephthalic acid with tetramethylenediamine, hexamethylenediamine, octamethylenediamine, trimethylhexamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, etc. Body, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, trimethylhexamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, etc. Polycondensate of Sofutaru acid.

  Among these thermoplastic polyamides, the most preferable one is thermoplastic polyamide having a melting point of 160 to 265 ° C., specifically, nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 610, nylon 612. , Nylon 46, nylon 11, nylon 12 and the like.

When the matrix of (c-1) is formed from a vulcanizable elastomer and a polyolefin, it may have a structure in which the polyolefin is dispersed in islands in the vulcanizable elastomer, and vice versa. A structure in which vulcanizable elastomer is dispersed in an island shape in polyolefin may be adopted. Each component is preferably bonded to each other at the interface.

  Most thermoplastic polymers having an amide group in the main chain are dispersed in the matrix as fine fibers. Specifically, 70% by weight, preferably 80% by weight, particularly preferably 90% by weight or more is dispersed as fine fibers. The fibers preferably have an average fiber diameter of 1 μm or less.

  Said (c-1) fiber reinforced rubber can be manufactured by the process of Unexamined-Japanese-Patent No. 8-3368, for example. That is, Step 1: A step of preparing a matrix, Step 2: A step of reacting a thermoplastic polymer having an amide group in the main chain with a binder, Step 3: A step of reacting the matrix with a thermoplastic polymer reacted with the binder. Melting and kneading step, step 4: The obtained kneaded product can be produced by extruding at a temperature equal to or higher than the melting point of the thermoplastic polymer and then stretching and / or rolling at a temperature lower than the melting point of the thermoplastic polymer. Melting and kneading can be performed by an apparatus usually used for kneading resin and rubber. Examples include Banbury mixers, kneaders, kneader extruders, open rolls, uniaxial kneaders, and biaxial kneaders.

  Binders include silane coupling agents, titanate coupling agents, novolak-type alkylphenol formaldehyde initial condensates, resol-type alkylphenol formaldehyde initial condensates, novolac-type phenolformaldehyde initial condensates, resol-type phenolformaldehyde initial condensates, unsaturated carboxylic acids. What is normally used as a high molecular coupling agent, such as an acid, its derivative (s), and an organic peroxide, can be used. Among these, (a silane coupling agent is preferable. Examples of the silane coupling agent include vinyl alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (β-methoxyethoxy) silane, vinyltriacetylsilane, γ- Hydrogen atoms from methacryloxypropyltrimethoxysilane, γ- [N- (β-methacryloxyethyl) -N, N-dimethylammonium (chloride)] propylmethoxysilane, styryldiaminosilane, vinyl group, alkyloxy group, etc. A silane coupling agent having a group and / or a polar group that easily desorbs and desorbs is preferably used, and when a silane coupling agent is used as a binder, an organic peroxide can be used in combination.

  The thermoplastic polymer component may be melt kneaded and reacted with a binder in advance and then melt kneaded with the matrix, or may be melt kneaded with the matrix in the presence of the binder.

  In the case of the binder for the thermoplastic polymer component, the range of 0.1 to 5.5% by weight is preferable when the total amount of the thermoplastic polymer component and the binder is 100% by weight.

  In this step, the temperature at which the matrix and the thermoplastic polymer component are melted and kneaded is preferably equal to or higher than the melting point of the thermoplastic polymer component. Even when melting and kneading are performed at a temperature lower than the melting point, the kneaded product does not have a structure in which fine particles of the thermoplastic polymer component are dispersed in the matrix. The kneading temperature is preferably a temperature equal to or higher than the melting point of the polyolefin or the Vicat softening point.

  The kneaded product obtained in the above step is extruded from a spinneret, an inflation die or a T die, and then stretched or rolled. In this step, the fine particles of the thermoplastic polymer component in the kneaded product are transformed into fibers by spinning or extrusion. This fiber is drawn by subsequent drawing or rolling to become a stronger fiber. Accordingly, spinning and extrusion are preferably performed at a temperature equal to or higher than the melting point of the thermoplastic polymer component, and stretching and rolling are preferably performed at a temperature lower than the melting point of the thermoplastic polymer component.

  Spinning or extrusion, and subsequent stretching or rolling can be performed by, for example, a method of extruding a kneaded material from a spinneret, spinning it into a string or thread, and winding it on a bobbin or the like while drafting. Here, “drafting” means that the winding speed is higher than the spinning speed. The ratio of winding speed / spinning speed (draft ratio) is preferably in the range of 1.5-100.

  In addition, this step can also be carried out by continuously rolling the spun kneaded material with a rolling roll or the like. Further, the kneaded product can be extruded from an inflation die or a T die and wound on a roll or the like while being drafted. Moreover, you may roll with a rolling roll etc. instead of winding on a roll, applying a draft.

  The (c-1) fiber-reinforced rubber after stretching or rolling is preferably pelletized. By using pellets, it becomes easy to uniformly knead with the following (c-2) natural rubber, diene rubber, and (c-3) carbon black.

  The fiber reinforced rubber composition of the component (C) of the present invention includes (c-2) the fiber reinforced rubber, (c-2) natural rubber and / or diene rubber, and (c-3) carbon black. What mix | blends is preferable.

  Examples of the (c-2) diene rubber include high cis-1,4-polybutadiene, low cis-1,4-polybutadiene, isoprene rubber, styrene-butadiene copolymer rubber, and isoprene-isobutylene copolymer. Can be mentioned. (C-3) Carbon black having a particle diameter of 90 μm or less and dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more is preferably used. For example, various carbon blacks such as HAF, FF, FEF, GPF, SAF, ISAF, and SRF are used.

  When the amount of the thermoplastic polymer is less than the lower limit, a rubber composition having a small ML and a large modulus of elasticity and a large number of bendings cannot be obtained, and when the amount of the thermoplastic polymer is larger than the upper limit, ML becomes large and processing becomes difficult. If the blending ratio of natural rubber or polyisoprene is outside the above range, the number of flexures of the vulcanizate tends to be small. If the amount of carbon black is less than the above lower limit, the pico abrasion index of the vulcanizate will be small, and if the amount of carbon black is larger than the above upper limit, the ML of the composition will be large.

  The (C) fiber-reinforced rubber composition of the present invention can be obtained by mixing the above components using a kneader such as a Banbury mixer, a kneader, an open roll, or a biaxial kneader. The kneading temperature is preferably lower than the melting point of the thermoplastic polymer constituting the fine short fibers in the fiber reinforced thermoplastic composition. When kneaded at a temperature higher than the melting point of the thermoplastic polymer, fine short fibers in the fiber-reinforced thermoplastic composition may melt and deform into spherical particles or the like.

(C) The fiber reinforced rubber composition is preferably in a pellet form. The pellet-like fiber reinforced rubber composition can be uniformly kneaded with the component (A) and the component (B), and a composition in which fine fibers are uniformly dispersed is easily obtained.

  The blending ratio of each component of the present invention is (A) natural rubber and / or diene synthetic rubber component 10 to 80% by weight, preferably 10 to 60% by weight, particularly preferably 10 to 30% by weight (B) reinforcement. The polybutadiene rubber component is 5 to 60% by weight, preferably 5 to 50% by weight, particularly preferably 10 to 50% by weight, and (C) the fiber reinforced rubber component 5 to 70% by weight, preferably 20 to 70% by weight. .

  The rubber composition of the present invention is preferably produced by the following steps. That is, a vulcanizable elastomer, a polyolefin, and a thermoplastic polymer having an amide group in the main chain are kneaded, and the main chain has an amide group in a matrix in which the vulcanizable elastomer is dispersed in the continuous phase of the polyolefin. The first step of preparing pellets in which the thermoplastic polymer is dispersed in the form of fine fibers. Furthermore, a vulcanizable elastomer is added and kneaded, and the polyolefin is dispersed in the continuous phase of the vulcanizable elastomer. It is preferable to produce in a second step of adjusting the master batch in which the phase structure of the matrix is changed, and a third step of adding and kneading the reinforced polybutadiene rubber component.

  Additives such as vulcanizing agents are blended in the rubber composition of the present invention. As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, sulfur-containing compounds and the like can be used. There is no restriction | limiting in particular about the method of mix | blending a vulcanizing agent with a rubber composition, The compounding method known per se is employable. Along with vulcanizing agent, white carbon, activated calcium carbonate, super fine magnesium silicate, high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin, petroleum resin and other reinforcing agents, various grades of calcium carbonate, Fillers such as basic magnesium carbonate, clay, zinc white, diatomaceous earth, recycled rubber, powder rubber, ebonite powder, aldehydes, ammonia, aldehydes / amines, guanidines, thioureas, thiazoles, thiurams, dithio Vulcanization accelerators such as carbamates and xanthates, vulcanization accelerators such as metal oxides and fatty acids, amines / aldehydes, amines / ketones, amines, phenols, imidazoles, sulfur-containing or phosphorus-containing Anti-aging agent, naphthenic, aromatic, paraffinic Seth oil, can be prepared to compositions formulated without impairing the effect of the present invention. In particular, the composition of the present invention preferably contains 1 to 30 parts by weight of process oil with respect to 100 parts by weight of rubber.

  The vulcanization temperature of the rubber composition of the present invention is preferably about 100 to 190 ° C. However, the vulcanization temperature needs to be lower than the melting point of the thermoplastic polymer constituting the fine fibers in the rubber composition. When vulcanization is performed at a temperature equal to or higher than the melting point of this thermoplastic resin, the fibers formed during the preparation of the fiber reinforced thermoplastic rubber composition are melted, resulting in a rubber having excellent workability and a large tensile elastic modulus of the vulcanizate. A composition may not be obtained.

The composition of this invention, vulcanizates M10 is 30kg / cm ² or more, preferably 100~30kg / cm ² or,, 3 Mpa or more, preferably 10～3Mpa, hardness 85 or more, preferably 150 to 85, The compression set (CS) is 70% or less, such as a high elastic modulus at low elongation, and tires have excellent characteristics.

  It can be used for tire members for industrial tires, passenger cars, buses, trucks, airplanes, etc., especially bead fillers, chafer rubbers, electric wire protection covers, side groove rubber joints, rubber sheets, vibration-proof rubbers, conveyor belts, and the like.

(1) Content of 1,2 polybutadiene crystal fiber: The remainder of the extraction of 2 g of vinyl cis polybutadiene rubber with 200 ml of n-hexane by boiling for 4 hours using a Soxhlet extractor is shown in parts by weight.
(2) Melting point of 1,2 polybutadiene crystal fiber: The boiling n-hexane extraction remainder was determined by the peak temperature of the endothermic curve by a differential scanning calorimeter (DSC).
(3) Crystal fiber form: Vinyl cis polybutadiene rubber is vulcanized with sulfur monochloride and carbon disulfide, and the vulcanized product is cut into ultrathin sections and doubled as rubber of vinyl cis polybutadiene with osmium tetrachloride vapor. The binding was stained and determined by observation with a transmission electron microscope.
(4) Microstructure of rubber content in vinyl cis-polybutadiene rubber; this was performed by infrared absorption spectrum analysis. The microstructure was calculated from the absorption intensity ratio of cis 740 cm ⁻¹ , trans 967 cm ⁻¹ and vinyl 910 cm ⁻¹ .
(5) Viscosity of toluene solution in vinyl cis polybutadiene rubber; viscosity of 5 wt% toluene solution at 25 ° C. was measured and expressed in centipoise (cp).
(6) [η] of rubber content in vinyl-cis-polybutadiene rubber; boiling n-hexane soluble content was collected by drying and measured with a toluene solution at a temperature of 30 ° C.
(7) Mooney viscosity; a value measured at 100 ° C. according to JIS K6300.
(8) Die swell: The diameter of the compound and the die orifice diameter at the time of extrusion at a shear rate of 100 ° C. and 100 sec ⁻¹ as an indication of the extrudability of the compound using a processability measuring device (Monsanto, MPT) (However, the ratio L / D = 1.5 mm / 1.5 mm) was measured to obtain.
(9) Green modulus: Unvulcanized rubber was punched out into a No. 3 dumbbell to obtain a test piece, which was measured at room temperature and a tensile speed of 200 mm / min.
(10) Tensile modulus: Tensile modulus M300 was measured according to JIS K6301.
(11) Adhesion strength with metal; measured according to ASTM D2229.

(B component)
(Example 1)
(A) Manufacture of vinyl cis polybutadiene Content of nitrogen gas substituted in a 1.5 L stainless steel reaction vessel with a stirrer 1.0 L of polymerization solution (butadiene; 31.5 wt%, 2-butenes: 28.8 wt% , Cyclohexane; 39.7 wt%), water 1.7 mmol, diethylaluminum chloride 2.9 mmol, carbon disulfide 0.3 mmol, cyclooctadiene 13.0 mmol, cobalt octoate 0.005 mmol, and 20 ° C. at 20 ° C. The mixture was stirred for 1 minute to carry out 1,4 cis polymerization. At this time, a small amount of the cis-polybutadiene polymerization solution was taken out of the reaction vessel and dried, and the viscosity of the toluene solution of the cis-polybutadiene rubber obtained was measured and found to be 175. Thereafter, 150 ml of butadiene, 1.1 mmol of water, 3.5 mmol of triethylalumonium chloride and 0.04 mmol of cobalt octoate were added, and the mixture was stirred at 40 ° C. for 20 minutes to carry out 1,2 syndiopolymerization. To this was added an anti-aging ethanol solution. Thereafter, unreacted butadiene and 2-butenes were removed by evaporation to obtain a vinyl cis polybutadiene having a yield of 66 g and HI; 40.5%. Of this, 58 g of vinyl cis polybutadiene was dissolved in cyclohexane to prepare a vinyl cis polybutadiene slurry.

(B) Production of cis-polybutadiene In a 1.5 L stainless steel reactor equipped with a stirrer and substituted with nitrogen gas, 1.0 L of a polymerization solution (butadiene; 31.5 wt%, 2-butenes; 28.8 wt%, Cyclohexane; 39.7 wt%), 1.7 mmol of water, 2.9 mmol of diethylaluminum chloride, 20.0 mmol of cyclooctadiene, 0.005 mmol of cobalt octoate, and the mixture is stirred at 60 ° C. for 20 minutes. Polymerization was performed. The polymerization was stopped by adding an anti-aging agent ethanol solution thereto. Thereafter, unreacted butadiene and 2-butenes were removed by evaporation to obtain 81 g of cis-polybutadiene having a Mooney viscosity of 29.0 and a toluene solution viscosity of 48.3. This operation was performed twice and a total of 162 g of cis-polybutadiene was dissolved in cyclohexane to prepare a cis-polybutadiene cyclohexane solution.

(A) + (b) Production of mixture vinyl cis-polybutadiene rubber A cis-polybutadiene cyclohexane solution in which 162 g of cis polybutadiene described above was dissolved in a 5.0 liter stainless steel reactor equipped with a stirrer was replaced with nitrogen gas. A vinyl cis polybutadiene cyclohexane slurry containing 58 g of the vinyl cis polybutadiene described above was added thereto with stirring. After adding the slurry, the mixture was stirred for 1 hour and then vacuum-dried at 105 ° C. for 60 minutes to obtain 220 g of (a) + (b) mixture vinyl cis-polybutadiene rubber. This polymer mixture was ML; 61.1, HI; 11.9%.

(C component) Preparation of fiber reinforced rubber component Polyethylene (manufactured by Ube Industries, F522), natural rubber (NR, SMR-L), nylon 6 (manufactured by Ube Industries, Ltd., Ube nylon 1030B, melting point 215-220 ° C, Molecular weight 30,000) was used. Polyethylene is melt kneaded with 0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane and 0.1 parts by weight of 4,4-di-tert-butylperoxyvaleric acid n-butyl ether with respect to 100 parts by weight. And denatured. Nylon 6 was modified by melting and kneading with 1.0 part by weight of N-β (aminoethyl) γ-aminopropyltrimethoxysilane with respect to 100 parts by weight.

  First, 100 parts by weight of polyethylene modified as described above was kneaded with 100 parts by weight of natural rubber using a Banbury mixer to prepare a matrix. This was dumped at 170 ° C. and pelletized. Next, 100 parts by weight of this matrix and nylon 6 were kneaded with a biaxial kneader heated to 240 ° C., and the kneaded product was pelletized. The obtained kneaded material was extruded into a string shape with a single screw extruder set at 245 ° C., and pelletized with a pelletizer while being drawn at a draft ratio of 10. The obtained pellet was refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyolefin and NR, and when the shape and diameter of the remaining fiber were observed with an electron microscope, the average fiber diameter was 0.2 μm. It was confirmed that it was a fiber. Component (C) was prepared by blending 50 parts by weight of the obtained pellets, 150 parts by weight of oil-extended S-SBR (manufactured by Zeon Corporation) and 50 parts by weight of ISAF carbon.

Claims (4)

A rubber composition comprising (A) natural rubber and / or diene-based synthetic rubber component 10 to 80% by weight, (B) reinforced polybutadiene rubber component 5 to 60% by weight, and (C) fiber reinforced rubber component 5 to 70% by weight. A rubber composition in which the component (B) and the component (C) have the following characteristics.
Component (B): (a) (1) A cis-obtained from an organoaluminum compound and a soluble cobalt compound in a mixture of water-adjusted 1,3-butadiene and hydrocarbon organic solvent as main components A step of adding 1,4 polymerization catalyst to cis-1,4 polymerization of 1,3-butadiene, and then (2) soluble cobalt compound and general formula AlR3 (where R is carbon in the polymerization reaction mixture obtained) A step of polymerizing 1,3-butadiene in the presence of a catalyst obtained from an organoaluminum compound represented by formula (1-6) alkyl group, phenyl group or cycloalkyl group and carbon disulfide. Vinyl cis-polybutadiene obtained from
(B) A reinforced polybutadiene rubber component obtained by adding the cis-1,4 polymerization catalyst and mixing the cis-polybutadiene obtained by cis-1,4 polymerization of 1,3-butadiene.
(C) component: (c-1) a fiber reinforced rubber in which a thermoplastic polyamide is dispersed in a fine fiber form in a matrix composed of a vulcanizable elastomer, and the thermoplastic polyamide is bonded to the matrix; (C-2) A fiber-reinforced rubber composition obtained by blending natural rubber and / or diene-based synthetic rubber and (c-3) carbon black. 2. The rubber composition according to claim 1, wherein the polymerization temperature in the step (1) of 1,3-butadiene polymerization of (a) and (2) is −5 to 50 ° C. 3. The rubber composition according to claim 1 or 2, wherein the vinyl cis-polybutadiene obtained in (a) has a boiling n-hexane insoluble fraction (HI) of 10 to 60% by weight. The cis-polybutadiene obtained in the cis-1,4 polymerization step (a) (1) has a 5% toluene solution viscosity (Tcp) of 150 to 250. The rubber composition as described.