JP4075911B2 - Method for producing vinyl cis-polybutadiene rubber - Google Patents

Description

The present invention is a carbon compound suitable for a tire having a small die swell and excellent extrudability while having excellent wet skid performance, heat generation characteristics, and wear resistance required for performance such as safety and economy of the tire. The present invention relates to a method for producing a rubber composition for silica compounding . The rubber composition produced in the present invention includes tire members such as sidewalls in tires, side reinforcing layers of run flat tires, carcass, belts, chafers, base treads, cap treads, beads, stiffeners, and inner liners. It can also be used for anti-vibration rubber, hoses, belts, rubber rolls, rubber coolers, shoe rubber, and other industrial products, other composites, adhesives, plastic modifiers, and the like.

  The polybutadiene has a so-called microstructure that includes a bond portion (1,4-structure) formed by polymerization at the 1,4-position and a bond portion (1,2-structure) formed by polymerization at the 1,2-position. Coexist in the molecular chain. The 1,4-structure is further divided into two types, a cis structure and a trans structure. On the other hand, the 1,2-structure has a structure in which a vinyl group is a side chain.

  Conventionally, a method for producing a vinyl-cis-polybutadiene composition composition has been carried out with an aromatic hydrocarbon solvent such as benzene, toluene, xylene and the like. When these solvents were used, the viscosity of the polymerization solution was high, and there were problems with stirring, heat transfer, transfer, etc., and excessive energy was required to recover the solvent.

As the above production method, water, a soluble cobalt compound and a general formula AlR _n X _3-n (where R is an alkyl group having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl group) are used. , X is a halogen element, n is a number from 1.5 to 2), and BR is produced by cis 1,4 polymerization of 1,3-butadiene using a catalyst obtained from an organoaluminum chloride. Then, a soluble cobalt compound and a general formula AlR ₃ (wherein R is an alkyl group having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl group) with or without the addition of 1,3-butadiene and / or the solvent to the polymerization system. 1,3-butadiene is synthesized in syndiotactic 1,2 polymerization (hereinafter abbreviated as 1,2 polymerization) in the presence of a catalyst obtained from an organoaluminum compound and carbon disulfide. (For example, see Japanese Patent Publication No. 49-17666 (Patent Document 1) and Japanese Patent Publication No. 49-17667 (Patent Document 2)).

  Also, for example, Japanese Patent Publication No. Sho 62-171 (Patent Document 3), Japanese Patent Publication No. Sho 63-36324 (Patent Document 4), Japanese Patent Publication No. 2-337927 (Patent Document 5), Japanese Patent Publication No. 2-38081 (Patent Document 6), Japanese Patent Publication No. 3-63566 (Patent Document 7) describes the production of 1,3-butadiene by cis 1,4 polymerization in the presence or absence of carbon disulfide, or after the production. A method is described in which 1,3-butadiene and carbon disulfide are separated and recovered to circulate 1,3-butadiene substantially free of carbon disulfide and the inert organic solvent. Further, Japanese Patent Publication No. 4-48815 (Patent Document 8) discloses a rubber composition having a small die-swell ratio and a vulcanizate that is suitable as a tire sidewall and excellent in tensile stress and flex crack growth resistance. Things are listed.

  JP-A-2000-44633 (Patent Document 9) discloses an inert organic solvent mainly composed of a C4 fraction such as n-butane, cis 2-butene, trans-2-butene, and butene-1. The method of manufacturing in is described. 1,2-polybutadiene contained in the rubber composition in this method is a short fiber crystal, and the distribution of the major axis length of the short fiber crystal is 98% or more of the fiber length is less than 0.6 μm, 70% It is described that the above is less than 0.2 μm, and the resulting rubber composition has the moldability, tensile stress, tensile strength, flex crack growth resistance of cis 1,4 polybutadiene rubber (hereinafter abbreviated as BR), etc. Is described as being improved. However, depending on the application, there has been a demand for rubber compositions with improved various properties.

Japanese Patent Publication No.49-17666 Japanese Patent Publication No.49-17667 Japanese Patent Publication No.62-171 Japanese Examined Patent Publication No. 63-36324 JP-B-2-37927 JP-B-2-38081 Japanese Examined Patent Publication No. 3-63566 Japanese Patent Publication No. 4-48815 JP 2000-44633 A

  The present invention is a vinyl produced by adding a specific polyisoprene to a syndiotactic-1,2-polybutadiene fiber crystal resin having a specific structure and a cis-polybutadiene rubber having a specific structure. The present invention relates to a method for producing a cis-polybutadiene rubber composition, and in particular, to provide a method for producing a vinyl cis-polybutadiene rubber composition exhibiting excellent properties as materials for automobile tire treads and sidewalls. To do.

  The present invention includes (1) 100 parts by weight of cis-polybutadiene as a matrix component, (2) 1 to 25 parts by weight of syndiotactic-1,2-polybutadiene fiber particles finely dispersed in the matrix, and (3) ML viscosity. A varnish / cis-polybutadiene composition comprising 0.01 to 50 parts by weight of polyisoprene having a molecular weight of 10 to 50, wherein (3) part or all of the polyisoprene is produced from vinyl cis-polybutadiene rubber. The present invention relates to a method for producing a vinyl cis-polybutadiene composition, which is sometimes added.

  In addition, the present invention relates to (1) a method for producing the above varnish / cis-polybutadiene composition, wherein the cis-polybutadiene has a cis structure content of 80% or more.

  (1) The above cis-polybutadiene composition having a weight average molecular weight of 300,000 to 800,000 and an intrinsic viscosity ([η]) of 1 to 5. The present invention relates to a method for manufacturing a product.

  (1) ML of the cis-polybutadiene is 10 to 50, T-cp is 10 to 150, and T-cp / ML is 1 to 10 above. The present invention relates to a method for producing a cis-polybutadiene composition.

  In addition, (2) the above-mentioned varnish / cis-polybutadiene composition, wherein the syndiotactic-1,2-polybutadiene has a melting point of 170 to 230 ° C. and ηsp / c of 1 to 5. It relates to the manufacturing method.

  (2) Production of the above-mentioned varnish / cis-polybutadiene composition, wherein the fiber particles and / or fiber particle aggregates of syndiotactic-1,2-polybutadiene are finely dispersed in a matrix. Regarding the method.

  The (3) polyisoprene is a graft reaction of the (2) syndiotactic-1,2-polybutadiene fiber particles, and relates to a process for producing the above-mentioned varnish / cis-polybutadiene composition.

  Further, the present invention relates to (3) the method for producing the vinice cis-polybutadiene composition described above, wherein the polyisoprene has a cis structure content of 90% or more.

  In addition, the present invention relates to (3) a method for producing the above-mentioned varnish / cis-polybutadiene composition, wherein the polyisoprene has a weight average molecular weight of 300,000 to 1,300,000.

  The present invention further relates to (4) a method for producing the above-mentioned varnish / cis-polybutadiene composition comprising 0.01 to 0.5 parts by weight of a phenolic antioxidant having one or more thioether structures.

Further, 1,3-butadiene is cis-1,4 polymerized in a hydrocarbon solvent using a cis-1,4 polymerization catalyst, and then the 1,2 polymerization catalyst is added to the obtained polymerization reaction product. By coexisting, 1,3-butadiene is polymerized 1,2 to produce 1,2-polybutadiene, and then the vinyl cis-polybutadiene rubber produced from the obtained polymerization reaction mixture is separated and recovered. The present invention relates to a method for producing the above-mentioned vinyl cis-polybutadiene composition.

  In addition, the vinyl cis described above is characterized in that a part or all of the (4) phenolic antioxidant having one or more thioether structures is added to the production system during the production of the vinyl cis-polybutadiene rubber. -It relates to a method for producing a polybutadiene composition.

  The varnish / cis-polybutadiene composition produced in the present invention has a high die-swell while maintaining a high wet skid property, is excellent in extrusion processability and moldability, improves the workability of tire production, and wear resistance. Excellent fuel economy.

  The vinyl cis-polybutadiene composition of the present invention has the following constitution. (1) 100 parts by weight of cis-polybutadiene as a matrix component, (2) 1 to 25 parts by weight of syndiotactic-1,2-polybutadiene fiber particles finely dispersed in the matrix, and (3) ML viscosity is 10 It consists of 0.01 to 50 parts by weight of polyisoprene which is ˜50.

(1) The cis-polybutadiene as the matrix component desirably has the following characteristics.
It is desirable that the cis structure content is 80% or more, preferably 90% or more, and does not substantially contain a gel component. Here, the phrase “substantially not containing a gel content” means that the toluene-insoluble content is 0.5% by mass or less.
That is, Mooney viscosity (ML _{1 + 4} 100 ° C., hereinafter abbreviated as “ML”) is preferably 10-50, preferably 10-40.
The toluene solution viscosity (centipoise / 25 ° C., hereinafter abbreviated as “T-cp”) is preferably 10 to 150, more preferably 10 to 100.
The weight average molecular weight is preferably 300,000 to 800,000.
[η] (intrinsic viscosity) is 1 to 5, preferably 1 to 4.
It is preferable that T-cp / ML is 1-10.

(2) The syndiotactic-1,2-polybutadiene fiber particles finely dispersed in the matrix have a melting point of 170 to 230 ° C., preferably 190 to 220 ° C., and ηsp / c of 1 to 1 5 is preferable.
The average monodisperse fiber crystal has a minor axis length of 0.2 μm or less, an aspect ratio of 10 or less, preferably 8 or less, and an average number of monodisperse fiber crystals of 10 or more, preferably 15 It is preferable to form crystal fibers having the above short fiber shape.

  It is preferable that fiber particles and / or fiber particle aggregates of syndiotactic-1,2-polybutadiene are finely dispersed in the matrix.

(3) As polyisoprene, ML viscosity is 10-50, Preferably, it is 15-45.
When the ML viscosity of polyisoprene is within the above range, the dispersion state of short fiber crystals of 1,2-polybutadiene crystal fibers in the cis-polybutadiene rubber matrix becomes good, and excellent die swell characteristics and high elasticity, It is preferable for the expression of tensile strength.
It is preferable that the polyisoprene has a cis structure content of 90% or more.
It is preferable that the weight average molecular weight of polyisoprene is 300,000 to 1,300,000.

The ratio of the cis-polybutadiene rubber as the component (1) to the 1,2-polybutadiene crystal fiber as the component (2) is 1,1 of the component (1) with respect to 100 parts by mass of the cis-polybutadiene rubber as the component (1). The amount of 2-polybutadiene crystal fiber is 1 to 25 parts by mass.
Within the above range, the short fiber crystals of 1,2-polybutadiene crystal fibers in the cis-polybutadiene rubber in the case of a large amount exceeding 50 parts by mass are likely to be large, resulting in poor dispersibility or 1 In the case of a small amount less than part by mass, it is possible to avoid a decrease in the reinforcing property due to the short fiber crystal. Therefore, the elastic modulus, extrusion processability, moldability, etc., which are features are difficult to be exhibited, and the processability is deteriorated. This is preferable because problems are unlikely to occur.

The proportion of the polyisoprene as the component (3) is 0.01 to 50 parts by mass, preferably 0.01 to 30 parts by mass of the vinyl cis-polybutadiene composition.
Being within the above range is preferable from the viewpoints of improvement in dispersibility due to aggregation of the 1,2-polybutadiene crystal fiber of the component (2), and suppression of deterioration of various physical properties brought about by the vinyl cis-polybutadiene composition.

  The composition of the present invention preferably further contains (4) 0.01 to 0.5 parts by weight of a phenolic antioxidant having one or more thioether structures.

Specific examples of phenolic antioxidants having one or more thioether structures include 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2 , 4-Bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,4-bis [(octylthio) methyl] -ortho -Cresol etc. are mentioned.

Among them, 2,4-bis [(octylthio) methyl] -ortho-cresol is preferable.

  Said vinyl cis-polybutadiene composition is suitably obtained, for example with the following manufacturing methods.

  In the production of the vinyl cis-polybutadiene composition of the present invention, 1,3-butadiene is generally polymerized using a hydrocarbon solvent. This hydrocarbon solvent is preferably a hydrocarbon solvent having a solubility parameter (hereinafter abbreviated as “SP value”) of 9.0 or less, more preferably a hydrocarbon solvent of 8.4 or less. Examples of the hydrocarbon solvent having a solubility parameter of 9.0 or less include, for example, n-hexane (SP value: 7.2) and n-pentane (SP value: 7) which are aliphatic hydrocarbons and alicyclic hydrocarbons. 0.0), n-octane (SP value: 7.5), cyclohexane (SP value: 8.1), n-butane (SP value: 6.6), and the like. Of these, cyclohexane and the like are preferable.

  The SP values of these solvents are known in documents such as the Rubber Industry Handbook (Fourth Edition, Japan Rubber Association, published on January 20, 1994; page 721).

By using a solvent having an SP value of less than 9.0, a dispersion state of short fiber crystals of 1,2-polybutadiene crystal fibers in the cis-polybutadiene rubber is formed as expected in the present invention. -It is preferable because it exhibits swell characteristics, high elasticity, and tensile strength.

  First, 1,3-butadiene and the solvent are mixed, and then the concentration of water in the obtained solution 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 used as a cis-1,4 polymerization catalyst described later in the solution. It is. In this range, sufficient catalytic activity can be obtained and a suitable cis-1,4 structure content and molecular weight can be obtained, while the generation of gel during polymerization can be suppressed, thereby preventing the gel from adhering to a polymerization tank or the like. It is preferable because the continuous polymerization time can 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.

To the solution obtained by adjusting the concentration of water, organoaluminum chloride is added as one of the cis-1,4 polymerization catalysts. As the organoaluminum chloride, a compound represented by the general formula AlR _n X _3-n is preferably used. Specific examples thereof include diethylaluminum monochloride, diethylaluminum monobromide, diisobutylaluminum monochloride, dicyclohexylaluminum monochloride, Preferred examples include diphenylaluminum monochloride, diethylaluminum sesquichloride and the like. The amount of organoaluminum chloride used is preferably 0.1 mmol or more, more preferably 0.5 to 50 mmol, per 1 mol of the total amount of 1,3-butadiene.

  Next, a soluble cobalt compound is added to the mixed solution to which the organoaluminum chloride is added as another cis-1,4 polymerization catalyst, and 1,3-butadiene is polymerized in cis-1,4. The soluble cobalt compound is soluble in the hydrocarbon solvent or liquid 1,3-butadiene used, or can be uniformly dispersed. For example, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate Cobalt β-diketone complex, cobalt β-keto acid ester complex such as cobalt acetoacetic acid ethyl ester complex, cobalt octoate, cobalt naphthenate, cobalt benzoate, etc. Examples include cobalt halide complexes such as cobalt pyridine complex and cobalt chloride ethyl alcohol complex. The amount of the soluble cobalt compound used is preferably 0.001 mmol or more, more preferably 0.005 mmol or more per mole of 1,3-butadiene. Further, 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 the soluble cobalt compound, an organic carboxylate of nickel, an organic complex of nickel, an organic lithium compound, an organic carboxylate of neodymium, or an organic complex of neodymium can be used.

  The temperature of cis-1,4 polymerization is generally in the temperature range from a temperature exceeding 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. It is preferable to perform the cis-1,4 polymerization so that the polymer concentration after the cis-1,4 polymerization is 5 to 26% by mass. 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 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.

  In the production of the vinyl cis-polybutadiene composition of the present invention, known molecular weight regulators such as cyclooctadiene, allene, and methylallene (1,2-butadiene) are used during cis-1,4 polymerization. Alternatively, α-olefins such as ethylene, propylene, and butene-1 can be used. Moreover, in order to further suppress the production | generation of the gel at the time of superposition | polymerization, a well-known gelation inhibitor can be used. In addition, the cis-1,4 structure content of the polymerization product is generally 80% or more, preferably 90% or more, and ML is 10 to 50, preferably 10 to 40, and does not substantially contain a gel content. .

Then, to the cis-1,4 polymerization reaction mixture obtained as described above, an organoaluminum compound represented by the general formula AlR ₃ and carbon disulfide, and if necessary, the soluble cobalt compound are added as 1,2 polymerization catalysts. Then, 1,3-butadiene is subjected to 1,2 polymerization to produce a vinyl cis-polybutadiene composition. At this time, 1,3-butadiene may be added to the polymerization reaction mixture, or unreacted 1,3-butadiene may be reacted without addition. Preferable examples of the organic aluminum compound represented by the general formula AlR ₃ include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and triphenylaluminum. The organoaluminum compound is 0.1 mmol or more, especially 0.5 to 50 mmol or more per mol 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 of 1,2 polymerization is generally in the temperature range of 0 to 100 ° C., preferably 10 to 100 ° C., more preferably 20 to 100 ° C. 1 to 50 parts by weight, preferably 1 to 20 parts by weight of 1,3-butadiene is added to 100 parts by weight of the cis-1,4 polymerization reaction mixture in the polymerization system for carrying out 1,2 polymerization. Thus, the yield of 1,2-polybutadiene during 1,2 polymerization can be increased. The polymerization time (average residence time) is preferably in the range of 10 minutes to 2 hours. It is preferable to perform the 1,2 polymerization so that the polymer concentration after the 1,2 polymerization is 9 to 29% by mass. 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, since the polymer becomes more viscous and easily adheres to the polymer during 1,2 polymerization, a polymerization tank equipped with a high-viscosity liquid stirring device, for example, described in JP-B-40-2645 An apparatus can be used.

In the production of the vinyl cis-polybutadiene composition of the present invention, when the vinyl cis-polybutadiene composition is produced by performing cis-1,4 polymerization and then 1,2 polymerization as described above, the ML viscosity is 10 It is desirable to include a step of adding polyisoprene, which is ˜50, into the production system of the vinyl cis-polybutadiene composition. Even if it is added at the time of compounding after the vinyl cis-polybutadiene composition is produced, the effect of the present invention cannot be obtained . The addition of polyisoprene into the production system is preferably performed in the polymerization reaction mixture at any time between the time when the cis-1,4 polymerization is performed and the time when the 1,2 polymerization is performed. More preferred is when 1,2 polymerization is carried out.

  Examples of polyisoprene include ordinary synthetic polyisoprene (such as cis-1,4-polyisoprene having a cis structure of 90% or more), natural rubber, liquid polyisoprene, trans-polyisoprene, and other modified polyisoprenes. Cis-1,4-polyisoprene having a cis structure of 90% or more is preferred.

  When polyisoprene is added as described above, the matrix of 1,2-polybutadiene having a melting point of 170 ° C. or higher is obtained in the vinyl cis-polybutadiene composition obtained as described above due to the compatibility effect of the unsaturated polymer substance. The dispersibility of the components in the cis-polybutadiene rubber is significantly improved, resulting in excellent properties of the resulting vinyl cis-polybutadiene composition.

  The addition of polyisoprene is preferably performed for 10 minutes to 3 hours after addition, and more preferably for 10 minutes to 30 minutes after addition.

  After the polymerization reaction reaches a predetermined polymerization rate, it is preferable to add the sulfur-containing phenol-based antioxidant when the polymerization is stopped or after the polymerization is stopped. A polymerization stopper is added to the polymerization system to stop the polymerization reaction. As the method, for example, after the completion of the polymerization reaction, the polymerization reaction mixture is supplied to a polymerization stop tank, and a large amount of a polar solvent such as alcohol such as methanol and ethanol and water is added to the polymerization reaction mixture. Examples thereof include methods known per se, such as a method of introducing an inorganic acid such as acetic acid and benzoic acid, and a method of introducing hydrogen chloride gas into the polymerization reaction mixture. Subsequently, the vinyl cis-polybutadiene composition produced according to the usual method is separated and recovered, washed and dried to obtain the desired vinyl cis-polybutadiene composition.

  In the method for producing the vinyl cis-polybutadiene composition of the present invention, the remaining unreacted 1,3-butadiene, hydrocarbon solvent and carbon disulfide obtained by separating the obtained vinyl cis-polybutadiene composition are obtained. In general, 1,3-butadiene and hydrocarbon solvents are separated from the mother liquor containing a polymerization reaction mixture by distillation, followed by carbon disulfide adsorption separation or carbon disulfide adduct separation treatment. The carbon is separated and removed, and 1,3-butadiene and hydrocarbon solvent substantially free of carbon disulfide are recovered. Also, carbon disulfide can be obtained by recovering three components from the polymerization reaction mixture mother liquor by distillation, and separating and removing carbon disulfide from the distillate by the adsorption separation or carbon disulfide deposit separation treatment. It is also possible to recover 1,3-butadiene and hydrocarbon solvent which are substantially not contained. The carbon disulfide and hydrocarbon solvent recovered as described above can be reused by mixing newly replenished 1,3-butadiene.

  According to the above-mentioned method for producing a vinyl cis-polybutadiene composition, the vinyl cis-polybutadiene composition of the present invention is continuously produced for a long period of time with excellent catalyst component operability and industrially advantageous with high catalyst efficiency. be able to. 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.

In order for the vinyl cis-polybutadiene composition produced as described above to exhibit excellent desired characteristics, 1,2-polybutadiene crystal fiber dispersed in the vinyl cis-polybutadiene composition is obtained by using cis-polybutadiene rubber. It is preferable that it is partially dispersed in the form of fine crystals in the matrix and coexists with large 1,2-polybutadiene crystal fibers having an aggregate structure. That is, the monodispersed 1,2-polybutadiene crystal fiber in the matrix of cis-polybutadiene rubber has an average monodisperse fiber crystal minor axis length of 0.2 μm or less and an aspect ratio of 10 or less. In addition, it is preferable that the average monodisperse fiber crystal number is 10 or more, and the melting point is 170 ° C. or more. In addition to the 1,2-polybutadiene crystal fiber having a melting point of 170 ° C. or higher, the unsaturated polymer substance is preferably dispersed in a cis-polybutadiene rubber matrix. This unsaturated polymer material has a high affinity with 1,2-polybutadiene crystal fiber in a matrix of cis-polybutadiene rubber and is dispersed in a state of being physically and chemically adsorbed in the vicinity of the crystal fiber. Preferably it is. As described above, 1,2-polybutadiene crystal fiber having a melting point of 170 ° C. or higher and an unsaturated polymer substance coexist and dispersed in a matrix of cis-polybutadiene rubber, whereby the above various properties are excellent. This is preferable.

  Next, the vinyl cis-polybutadiene composition of the present invention can be used for a tire member. Furthermore, rubbery polymers other than the above-mentioned vinyl-cis polybutadiene composition may be blended.

  Examples of the diene rubber (b) include high cis polybutadiene rubber, low cis polybutadiene rubber (BR), natural rubber, polyisoprene rubber, emulsion polymerization or solution polymerization styrene butadiene rubber (SBR), ethylene propylene diene rubber (EPDM). , Nitrile rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR) and the like.

  In addition, derivatives of these rubbers such as polybutadiene rubber modified with tin compounds and the above-mentioned rubbers modified with epoxy, silane, and maleic acid can be used. These rubbers can be used alone or in combination of two or more. May be.

  The vinyl cis-polybutadiene composition of the present invention preferably contains a rubber reinforcing agent. Carbon black having a particle size of 90 nm or less and dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more, for example, FEF, FF, GPF, SAF, ISAF, SRF, HAF and the like. Examples of silica include anhydrous silicic acid by a dry method, hydrous silicic acid by a wet method, and synthetic silicate. In addition, as rubber reinforcing agents, inorganic reinforcing agents such as activated calcium carbonate and ultrafine magnesium silicate, syndiotactic 1,2 polybutadiene resin, polyethylene resin, polypropylene resin, high styrene resin, phenol resin, lignin, modified melamine resin, You may mix organic reinforcement agents, such as a malon indene resin and petroleum resin.

  As a blending ratio of each of the above components, 100 parts by weight of a rubber component comprising 20 to 80% by weight of a vinyl / cis polybutadiene composition and 80 to 20% by weight of a rubbery polymer other than the vinyl / cis polybutadiene composition, rubber A proportion of 40 to 100 parts by weight of reinforcing agent is preferred.

  When the amount of the vinyl cis polybutadiene is less than the lower limit, a rubber composition having a large die swell and low exothermic property of the vulcanizate cannot be obtained, and when the amount of the vinyl cis polybutadiene is larger than the upper limit, the composition The Mooney viscosity of the product becomes too large and the moldability becomes poor. If the amount of the rubber reinforcing agent is less than the lower limit, the elastic modulus of the vulcanizate is lowered. Conversely, if the amount is larger than the upper limit, the Mooney viscosity becomes too large and the tire moldability tends to deteriorate. On the other hand, if the rubber ratio is out of the above range, the abrasion resistance of the vulcanizate is lowered.

The vinyl cis-polybutadiene composition of the present invention can be obtained by kneading the above components using a conventional Banbury, open roll, kneader, biaxial kneader or the like.
The kneading temperature needs to be lower than the melting point of the 1,2 polybutadiene crystal fiber contained in the vinyl cis polybutadiene. Kneading at a temperature higher than the melting point of the 1,2 polybutadiene crystal fibers is not preferable because fine short fibers in the vinyl-cis polybutadiene are melted and deformed into spherical particles.

  If necessary, the rubber composition of the present invention is kneaded with compounding agents usually used in the rubber industry, such as vulcanizing agents, vulcanization aids, anti-aging agents, fillers, process oils, zinc white, and stearic acid. May be.

  As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, resin vulcanizing agents, and metal oxides such as magnesium oxide are used.

  As the vulcanization aid, known vulcanization aids such as aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, xanthates and the like are used.

  Examples of the anti-aging agent include amine / ketone series, imidazole series, amine series, phenol series, sulfur series and phosphorus series.

  Examples of the filler include inorganic fillers such as calcium carbonate, basic magnesium carbonate, clay, Lissajous and diatomaceous earth, and organic fillers such as recycled rubber and powder rubber.

  The process oil may be any of aromatic, naphthenic, and paraffinic.

  The vinyl cis-polybutadiene composition of the present invention is improved in die swell performance, wear resistance performance and low fuel consumption performance while maintaining wet skid properties, and is more highly balanced in tire tread performance. Suitable for applications such as side walls.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the examples and comparative examples, the physical properties of the rubber rubber of the vinyl cis-polybutadiene composition, and the physical properties of the resulting silica compound rubber composition for tire and the physical properties of the vulcanizate were measured as follows. .
(1) Content of 1,2 polybutadiene crystal fiber : The remainder of the extraction of 2 g of vinyl cis-polybutadiene composition by boiling with a Soxhlet extractor in 200 ml of n-hexane for 4 hours 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 : The vinyl cis-polybutadiene composition was vulcanized with sulfur monochloride and carbon disulfide, and the vulcanized product was cut into ultra-thin sections and osmium tetrachloride vaporized to give the rubber content of vinyl cis-polybutadiene. The double bond was stained and observed with a transmission electron microscope.
(4) Microstructure of rubber in the vinyl cis-polybutadiene composition ; the analysis 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 of rubber in vinyl cis-polybutadiene composition ; 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 composition ; 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.

(Example 1)
A solution prepared by dissolving 1.6 kg of 1.3-butadiene in 18 kg of dehydrated cyclohexane was placed in a 30-liter stainless steel reactor equipped with a stirrer, which was replaced with nitrogen gas, and 4 mmol of cobalt octoate, 84 mmol of diethylaluminum chloride, and 1,5- 70 mmol of cyclooctadiene was mixed and stirred at 25 ° C. for 30 minutes to carry out cis polymerization. The results of the obtained polymer are shown in Table 1. After cis polymerization, 5% by mass of polyisoprene (IR) (showing physical property values in Table 1) (percentage of the obtained vinyl-cis polybutadiene rubber) is added to the resulting polymerization product solution, and the mixture is stirred at 25 ° C. for 1 hour. went. Immediately thereafter, 90 mmol of triethylaluminum and 50 mmol of carbon disulfide were added to the polymerization solution, and the mixture was further stirred for 60 minutes at 25 ° C. to carry out 1,2 polymerization. After completion of the polymerization, the polymerization product solution was added to 18 L of methanol containing 2,4-bis [(octylthio) methyl] -ortho-cresol: 0.1 wt% to precipitate and precipitate a rubbery polymer. After separating and washing with methanol, it was vacuum dried at room temperature. The yield of vinyl cis-polybutadiene rubber thus obtained was 80%. Thereafter, the vinyl cis-polybutadiene rubber was treated with boiling n-hexane, and the insoluble and soluble components were separated and dried. The results of the obtained composition are shown in Tables 1 and 2.

(Examples 2 to 8 )
The same procedure as in Example 1 was performed except that polyisoprene (IR) shown in Table 1 was used. Tables 1 and 2 show the results.

(Comparative Examples 1-7)
The same procedure as in Example 1 was performed except that polyisoprene (IR) shown in Table 3 was used. Tables 3 and 4 show the results. In addition, “at the time of blending” in the IR addition method means that the composition obtained by polymerization is not added to the polymerization system but is added when blended as a vulcanized composition.

Claims (12)

(1) 100 parts by weight of cis-polybutadiene as a matrix component, (2) 1 to 25 parts by weight of syndiotactic-1,2-polybutadiene crystal fiber dispersed in the matrix, and (3) ML viscosity is 10 to 50 made from one polyisoprene 0.01 to 50 parts by weight, vinyl Le cis - a polybutadiene rubber composition, the (3) a portion of polyisoprene or all, vinyl-cis - added during production of the polybutadiene rubber A process for producing a vinyl cis-polybutadiene rubber composition . The method for producing a vinyl-cis-polybutadiene rubber composition according to claim 1, wherein the cis-polybutadiene has a cis structure content of 80% or more. The vinyl cis of claim 1 or 2, wherein the (1) cis-polybutadiene has a weight average molecular weight of 300,000 to 800,000 and an intrinsic viscosity ([η]) of 1 to 5. A method for producing a cis-polybutadiene rubber composition . The ML of the (1) cis-polybutadiene is from 10 to 50, T-cp is from 10 to 150, and T-cp / ML is from 1 to 10, A process for producing a vinyl cis-polybutadiene rubber composition according to claim 1 . The vinyl according to any one of claims 1 to 4, wherein the syndiotactic-1,2-polybutadiene (2) has a melting point of 170 to 230 ° C and ηsp / c of 1 to 5. A method for producing a cis-polybutadiene rubber composition . 6. The vinyl cis- (1) according to any one of claims 1 to 5, wherein the crystal fibers and / or crystal fiber aggregates of the (2) syndiotactic-1,2-polybutadiene are dispersed in a matrix. A method for producing a polybutadiene rubber composition . The vinyl cis-polybutadiene rubber according to any one of claims 1 to 6, wherein the (3) polyisoprene is graft-reacted with the (2) syndiotactic-1,2-polybutadiene crystal fiber. A method for producing the composition . The method for producing a vinyl-cis-polybutadiene rubber composition according to any one of claims 1 to 7, wherein the cis structure content of the (3) polyisoprene is 90% or more. The method for producing a vinyl-cis-polybutadiene rubber composition according to any one of claims 1 to 8, wherein the (3) polyisoprene has a weight average molecular weight of 300,000 to 1,300,000. The vinyl cis-polybutadiene rubber according to any one of claims 1 to 9, further comprising (4) 0.01 to 0.5 parts by weight of a phenolic antioxidant having at least one thioether structure. A method for producing the composition . 1,3-Butadiene is subjected to cis-1,4 polymerization in a hydrocarbon solvent using a cis-1,4 polymerization catalyst to form (1) cis-polybutadiene, and then the polymerization reaction obtained A 1,2 polymerization catalyst was allowed to coexist in the mixture, and 1,3-butadiene was subjected to 1,2 polymerization to produce the above-mentioned (2) syndiotactic-1,2-polybutadiene crystal fiber , and then obtained. The method for producing a vinyl cis-polybutadiene rubber composition according to any one of claims 1 to 10, wherein the vinyl cis-polybutadiene rubber composition produced from the polymerization reaction mixture is separated and recovered. 12. The vinyl according to claim 11, wherein a part or all of the phenolic antioxidant having one or more (4) thioether structures is added to the production system during the production of the vinyl cis-polybutadiene rubber. A method for producing a cis-polybutadiene rubber composition .