JP3775510B2 - Rubber composition for tire and tire - Google Patents

Description

  The present invention relates to a tire rubber comprising cis-1,4-polybutadiene rubber having improved unrolled rubber roll wrapping properties, extrusion processability, vulcanized rubber wear resistance, impact resilience, heat generation characteristics and strength characteristics. The present invention relates to a composition and a tire comprising the same.

  Conventionally, cis-1,4-polybutadiene rubber has been used in various parts of a tire, such as a tread part and a side wall part, taking advantage of features such as wear resistance, high resilience, and low heat build-up. Problems remain in workability such as tensile strength, roll winding property, and extrusion workability. So far, various improvements have been devised as means for improving cis-1,4-polybutadiene. However, the strength characteristics and processability of the cis-1,4-polybutadiene rubber have not been lost. No way to improve has been found.

  For example, Patent Document 1 discloses a method for improving workability by adding low molecular weight polybutadiene having a viscosity average molecular weight of 20,000 to 140,000 to cis-1,4-polybutadiene rubber to impart adhesiveness to the blend. Although disclosed, since this method uses a large amount of low-molecular-weight polybutadiene, it is not preferable because wear resistance, impact resilience, heat build-up, tensile properties, etc. deteriorate. Moreover, in patent document 2, the molecular weight distribution (Mw / Mn) is reduced to 3.0 to 3.5 using a catalyst composed of nickel compound / boron halide / aluminum compound / alcohol to improve the extrusion processability. However, in this method, the extrusion length at the time of extrusion processing, workability such as die swell, etc. are not yet sufficient, and the tensile strength and wear resistance are not sufficient. Furthermore, in Patent Document 3, syndiotactic-1,2-polybutadiene rubber is dispersed in cis-1,4-polybutadiene rubber, the molecular weight distribution (Mw / Mn) is 2.6 to 3.0, and the toluene solution viscosity ( (SV) and Mooney viscosity (ML) have a relationship of 3 × ML-30 <SV <3 × ML + 30, and a method for improving the extrusion processability, wear resistance, and strength characteristics is disclosed. The method does not have sufficient properties such as rebound resilience and heat generation.

JP-A-56-36532 Japanese Patent Laid-Open No. 5-9228 JP-A-5-194658

  As a result of intensive studies in view of such circumstances, the present inventors have found that, when a cis-1,4-polybutadiene rubber having a narrow molecular weight distribution and a very small degree of branching is used, roll winding property, extrusion processability, etc. A cis-1,4-polybutadiene rubber having improved processability and further improved properties such as wear resistance, impact resilience, heat build-up and strength properties, and a narrow molecular weight distribution and a low degree of branching, It can be produced by polymerizing 1,3-butadiene in the presence of a predetermined amount of molecular weight regulator and orthoester using a catalyst containing a predetermined amount of water, and the cis-1,4-polybutadiene rubber can be produced by natural rubber, etc. By blending with other diene rubbers, roll wrapping property and extrusion processability are remarkably improved, and wear resistance, impact resilience, heat generation and strength properties are improved. It found that rubber compositions balance each time is obtained, and have completed the present invention.

Thus, according to the present invention, the rubber component has a weight average molecular weight (Mw) measured by gel permeation chromatography of 100,000 to 1,000,000, and the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn). (Mw / Mn) is 2.5 or less, and the ratio (Rz / Mz) of Z average mean square rotation radius (Rz) to Z average absolute molecular weight (Mz) is 50 × 10 ⁻¹² m · mol · kg ⁻¹ or more. A rubber composition for a tire is provided in which the cis-1,4-polybutadiene rubber is 10% by weight or more in the total rubber component. According to this invention, the tire which consists of said rubber composition for tires is provided.

  The rubber composition for tires of the present invention exhibits excellent properties such as processability, wear resistance, impact resilience, heat build-up and strength properties, and therefore uses that properties, i.e., treads, carcass, sidewalls, beads. It can be used for tire parts such as parts. In particular, the tire rubber composition of the present invention is excellent in tire treads, side walls, and the like of fuel-efficient tires, taking advantage of the above characteristics. In addition, all-season tires, high-performance tires, truck and bus tires, studless It can be used for tire treads such as tires, side walls, under treads, carcass, beat parts and the like.

Cis-1,4-polybutadiene rubber The cis-1,4-polybutadiene rubber used in the present invention is a polybutadiene rubber having a cis-1,4-butadiene bond as a main component and usually has a cis-1,4-bond amount of all bonds. The amount of butadiene is 60% or more, preferably 80% or more, and more preferably 95% or more. When the amount of cis-1,4-bond is excessively small, the tensile strength and the resilience are inferior. The remaining microstructure (trans-1,4-butadiene bond amount and 1,2-vinylbutadiene bond amount) is not particularly limited.

  The molecular weight of the cis-1,4-polybutadiene rubber is 100,000 to 1,000,000, preferably 200,000 to 800,000, more preferably 30 in terms of weight average molecular weight (Mw) in terms of standard polystyrene measured by gel permeation chromatography. It is in the range of 10,000 to 600,000. If the weight average molecular weight is excessively small, the tensile strength and abrasion resistance are not sufficient. Conversely, if the weight average molecular weight is excessively large, the Mooney viscosity of the blend is high and the processability is poor, and neither is preferable.

  The molecular weight distribution of the cis-1,4-polybutadiene rubber is 2.5 or less in terms of the ratio (Mw / Mn) of the weight average molecular weight (Mw) measured above to the number average molecular weight (Mn) measured under the same conditions. , Preferably 1.5 to 2.4, and more preferably 1.8 to 2.3. If the molecular weight distribution is excessively large, the die swell at the time of extrusion processing is large, and the vulcanized physical properties such as wear resistance and impact resilience are inferior.

The degree of branching of cis-1,4-polybutadiene rubber was determined by gel permeation chromatography and multi-angle laser based on “Multi-angle light scattering detector DAWN explanatory material (issue date: July 1992)” issued by Shoko Tsusho Corporation. The mean square rotation radius (Ri) and absolute molecular weight (Mi) of each fraction measured by a light scattering detector (hereinafter abbreviated as GPC-MALLS method) are Z-averaged according to the following general formulas (1) and (2). The ratio (Rz / Mz) calculated for the mean square turning radius (Rz) and the Z average absolute molecular weight (Mz) is 50 × 10 ⁻¹² m · mol · kg ⁻¹ or more, preferably 55 × 10 ⁻¹² to 200 ×. The range is 10 ⁻¹² m · mol · kg ⁻¹ , more preferably 60 × 10 ^{−12 to} 100 × 10 ⁻¹² m · mol · kg ⁻¹ . If the Rz / Mz value is excessively small, roll rollability and heat generation are inferior.
Rz = Σ (CiMiRi) / Σ (CiMi) (1)
Mz = Σ (CiMi ² ) / Σ (CiMi) (2)
(In the formula, Ci represents each fraction concentration.)

The degree of branching of the polymer decreases as the Rz / Mz value increases, and increases as the Rz / Mz value decreases. The polymer having a large Rz / Mz value of 50 × 10 ⁻¹² m · mol · kg ⁻¹ or more of the present invention is a polymer having a very low degree of branching.

  The ratio of the solution viscosity (SV) / Mooney viscosity (ML) is also used as an index for determining the degree of branching of the polymer. In this method, however, a concentrated solution is used, so the molecular weight of the polymer and the molecular weight distribution due to the molecular weight distribution are used. The interaction is involved, and it cannot be said that it truly shows the degree of branching. The Rz / Mz value defined in the present invention is influenced by other mutual factors than the SV / ML value because the GPC-MALLS method is measured in a dilute solution and the ratio of the mean square rotation radius per absolute molecular weight is compared. The difference in the degree of branching of the polymer can be compared.

  The cis-1,4-polybutadiene rubber of the present invention having a low degree of branching (Rz / Mz value is large) and a small molecular weight distribution (Mw / Mn) is an halogenated organoaluminum compound in an inert organic solvent. When 1,3-butadiene is polymerized in the presence of a molecular weight regulator and an orthoester using a polymerization catalyst comprising a transition metal compound and water, the molar ratio of water to the halogen-containing organoaluminum compound is 0.1 or more, 1 , 3-Butadiene is produced by using 1 to 30 mmol of molecular weight modifier and 0.005 to 0.5 mmol of orthoester, but not limited to this method.

The halogen-containing organoaluminum compound is represented by, for example, the general formula AlR _3-n Xn (wherein R is an alkyl group, aryl group, cycloalkyl group, X is a halogen atom, and n is 1 or 2). Can be used. R in the formula represents an alkyl group, an aryl group or a cycloalkyl group, preferably an alkyl group. The carbon number of R is not particularly limited, but is usually 1 to 20, preferably 1 to 10, more preferably 1 to 5. Examples of the halogen atom for X include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, preferably a chlorine atom and a bromine atom, and more preferably a chlorine atom.

  Preferred halogen-containing organoaluminum compounds include, for example, dialkylaluminum monohalide compounds, dicycloalkylaluminum monohalide compounds, diarylaluminum monohalide compounds, alkylaluminum dihalide compounds, cycloalkylaluminum dihalide compounds, arylaluminum dihalide compounds, and the like. Is mentioned. Among these, a dialkylaluminum monohalide compound and an alkylaluminum dihalide compound are preferable, and a dialkylaluminum monochloride compound and an alkylaluminum monochloride compound are particularly preferable.

  Specifically, for example, dimethyl aluminum monochloride, diethyl aluminum monochloride, diisopropyl aluminum monochloride, di-n-propyl aluminum monochloride, di-n-butyl aluminum monochloride, diisobutyl aluminum monochloride, diethyl aluminum monofluoride Dialkylaluminum monohalide compounds such as diethylaluminum monobromide and diethylaluminum monoiodide; Dicycloalkylaluminum halide compounds such as dicyclohexylaluminum monochloride; Diarylaluminum monohalide compounds such as diphenylaluminum monochloride; Methylaluminum dichloride and ethylaluminum Dichloride, n-pro Alkyl aluminum dihalide compounds such as rualuminum dichloride, isopropylaluminum dichloride, n-butylaluminum dichloride, isobutylaluminum dichloride, n-hexylaluminum dichloride, ethylaluminum difluoride, ethylaluminum dibromide; cycloalkylaluminum such as cyclohexylaluminum dichloride Dihalide compounds; arylaluminum dihalide compounds such as phenylaluminum dichloride; and the like. Among these, diethyl aluminum monochloride, diisopropyl aluminum monochloride, di-n-propyl aluminum monochloride, di-n-butyl aluminum monochloride, diisobutyl aluminum monochloride, ethyl aluminum dichloride, n-propyl aluminum dichloride, isopropyl aluminum dichloride N-butylaluminum dichloride, isobutylaluminum dichloride and the like are particularly preferable.

  These halogen-containing organoaluminum compounds can be used alone or in combination of two or more. The amount of the halogen-containing organoaluminum compound used is usually in the range of 0.01 to 10 mmol, preferably 0.1 to 5 mmol, more preferably 0.5 to 2 mmol, per mol of 1,3-butadiene.

  The transition metal compound is not particularly limited as long as it has a transition metal and is soluble in a polymerization solvent. Usually, a transition metal salt compound is used. A transition metal is defined as a metal element with an incomplete d or f subshell or a metal element that produces a cation with such a subshell and is usually a periodic table according to the revised IUPAC inorganic chemistry nomenclature (1989). Group 3-11 elements can be mentioned. Specific examples include titanium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, lanthanum, and neodymium, preferably iron, cobalt, and nickel, and particularly preferably cobalt. Examples of the salt compound include organic acid salts and organic complex salts, with organic acid salts being preferred. The carbon number of the organic acid salt or the organic complex salt is not particularly limited, but is usually in the range of 1 to 30, preferably 2 to 25, and more preferably 3 to 20. Examples of the organic acid salt include monocarboxylic acid salts such as hexanoic acid, octenoic acid, stearic acid, naphthenic acid, and benzoic acid. Examples of organic complex salts include β-diketone complex salts, pyridine complex salts, phosphine complex salts, oxime complex salts, and the like.

  Preferred transition metal compounds include, for example, iron organic acid salts such as iron hexanoate, iron octenoate, iron stearate, iron acetylacetone, iron naphthenate, and iron benzoate; cobalt acetate, cobalt propionate, cobalt butyrate, hexanoic acid Cobalt organic acid salts such as cobalt, cobalt octenoate, cobalt laurate, cobalt stearate, cobalt isostearate, cobalt naphthenate, cobalt benzoate; nickel hexanoate, nickel octenoate, nickel stearate, nickel naphthenate, benzoic acid Nickel organic acid salt such as nickel; cobalt β-diketone complex salt such as acetylacetocobalt; nickel β-diketone complex salt such as acetylacetonickel; cobalt pyridine complex salt such as cobalt chloride pyridine complex salt; cobalt chloride Cobalt phosphine complex salts such as a rephenylphosphine complex salt; cobalt oxime complex salts such as a cobalt dimethylglyoxime complex salt; nickel oxime complex salts such as a nickel dimethylglyoxime complex salt; Among these, cobalt acetate, cobalt propionate, cobalt butyrate, cobalt hexanoate, cobalt octenoate, cobalt laurate, cobalt stearate, cobalt isostearate, acetylacetocobalt, cobalt naphthenate, cobalt benzoate, nickel hexanoate, Nickel octenoate, nickel stearate, nickel naphthenate, nickel benzoate and the like are preferable, and cobalt hexanoate, cobalt octenoate, cobalt stearate, cobalt naphthenate, cobalt benzoate and the like are particularly preferable.

  These transition metal compounds can be used alone or in combination of two or more. The amount of the transition metal compound used is appropriately selected depending on the required molecular weight, the type and amount of the molecular weight regulator used, and is usually 0.001 to 1 mmol, preferably 0, per mole of 1,3-butadiene. The range is 0.005 to 0.5 mmol, more preferably 0.01 to 0.1 mmol.

  Water is important in stably improving the catalyst activity and adjusting the molecular weight distribution and the degree of branching of the produced polymer. The amount of water used is 0.1 or more, preferably 0.2 to 0.8, and more preferably 0.3 to 0.6 in terms of molar ratio to the halogen-containing organoaluminum compound. When the amount of water used is excessively small, the resulting cis-1,4-polybutadiene has a large degree of branching and a wide molecular weight distribution, which is not preferable. On the other hand, when the amount of water is excessively large, the polymer may be gelled, which is not preferable. Water is usually added and dispersed in these media before the halogen-containing organoaluminum compound is added to the polymerization solvent or the polymerization solution of 1,3-butadiene.

  The inert organic solvent as a polymerization solvent is not particularly limited as long as it dissolves cis-1,4-polybutadiene rubber and does not adversely affect the activity of the polymerization catalyst. For example, aromatic hydrocarbons such as benzene, toluene and xylene, alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and cyclopentane, aliphatic hydrocarbons such as n-butane, n-hexane and n-heptane, Aliphatic unsaturated hydrocarbons such as cis-2-butene, trans-2-butene, and butene-1.

  These inert organic solvents are used alone or in combination of two or more. The amount of the solvent used is adjusted so that the monomer concentration is usually in the range of 5 to 50% by weight, preferably 10 to 35% by weight.

  As the molecular weight regulator used, those generally used in the polymerization reaction of cis-1,4-polybutadiene rubber are used, and usually one carbon-carbon unsaturated bond in the molecule or two or more not conjugated. An unsaturated hydrocarbon compound having a carbon-carbon unsaturated bond is used. Although carbon number of an unsaturated hydrocarbon compound does not have limitation in particular, Usually, 2-30, Preferably it is 2-20, Preferably it is 3-15.

  Preferable molecular weight regulators include, for example, α-olefin compounds, internal olefin compounds, terminal acetylene compounds, internal acetylene compounds, allene compounds, non-conjugated diene compounds, and the like. Among these, an α-olefin compound, an allene compound, a nonconjugated diene compound, and the like are preferable, an allene compound and a cyclic nonconjugated diene compound are more preferable, and an allene compound is particularly preferable.

  Specifically, for example, α-olefins such as ethylene, propylene, 1-butene and 1-pentene; terminal acetylene compounds such as acetylene, propylene and 1-butyne; 2-butyne, 2-pentyne, 2-hexyne, 3 -Internal acetylene compounds such as hexyne; allene compounds such as propadiene, 1,2-butadiene, 1,2-pentadiene; 1,4-pentadiene, 1,5-pentadiene, 1,5-cyclooctadiene, norbornadiene, dicyclo Non-conjugated diene compounds such as pentadiene; and the like. Among these, propylene, 1-butene, 1-pentene, propadiene, 1,2-butadiene, 1,2-pentadiene, 1,4-pentadiene, 1,5-pentadiene, 1,5-cyclooctadiene, norbornadiene, Dicyclopentadiene and the like are preferable, and propadiene, 1,2-butadiene, 1,2-pentadiene, 1,5-cyclooctadiene and the like are particularly preferable.

  These molecular weight regulators can be used alone or in combination of two or more. The amount of the molecular weight modifier used also affects the degree of branching of the produced polymer, and is preferably 1 to 30 mmol, preferably 1.5 to 20 mmol, more preferably 2 to 10 mmol, per mol of 1,3-butadiene. It is a range. If the amount of the molecular weight regulator used is too small, the degree of polymer branching will not be sufficiently small, and the vulcanization properties such as roll wrapping and heat generation will be inferior, and conversely if too large, the molecular weight of the polymer will be adjusted. It is difficult to obtain a polymer having a sufficient molecular weight, which is not preferable.

  The orthoester used is not particularly limited as long as the carboxyl group of the carboxylic acid is changed to a trialkyloxy group, but a trialkyl ester of a monocarboxylic acid is usually used. Although carbon number of monocarboxylic acid does not have limitation in particular, Usually, 1-20, Preferably it is 1-10, More preferably, it is the range of 1-6. The carbon number of the alkyl of the trialkyloxy group may be different or the same, and is not particularly limited, but is usually 1 to 20, preferably 1 to 10, and more preferably 1 to 6.

  Preferred orthoesters include, for example, orthoformates such as trimethyl orthoformate, triethyl orthoformate, trihexyl orthoformate; orthoacetic esters such as trimethyl orthoacetate, triethyl orthoacetate, trihexyl orthoacetate; triethyl orthopropionate, ortho Orthopropionates such as triethyl propionate; orthobutyric acid esters such as trimethyl orthobutyrate and triethyl orthobutyrate; orthooctanoic acid esters such as trimethyl orthooctanoate and triethyl orthooctanoate; trimethyl orthostearate and orthostearic acid And orthostearic acid esters such as triethyl. Among these, orthoformate esters, orthoacetate esters and the like are preferable, and orthoformate esters are particularly preferable.

  These orthoesters can be used alone or in combination of two or more. The amount of orthoester used is in the range of 0.005 to 0.5 mmol, preferably 0.01 to 0.1 mmol, more preferably 0.01 to 0.05 mmol, per mole of 1,3-butadiene. . If the amount of orthoester used is too small, the degree of branching and molecular weight distribution of the produced polymer cannot be reduced, and the produced polymer is easily gelled. Is lowered and productivity is inferior.

  The narrow molecular weight distribution and the small degree of branching that are characteristic of the cis-1,4-polybutadiene rubber used in the present invention are achieved by controlling the water content of the reaction, the amount of molecular weight regulator and the amount of orthoester. That is, simply increasing the amount of water in the catalyst has limitations for reducing the molecular weight distribution and the degree of branching, and causes problems such as generation of a gel during polymerization. On the other hand, an effective method for reducing the molecular weight distribution and the degree of branching is to increase the amount of orthoester added. However, when the orthoester alone is used excessively, sufficient polymerization activity is obtained. Problems occur. Further, the molecular weight modifier reduces the degree of branching of the polymer. The degree of activity varies depending on the type of molecular weight regulator, but is preferably large when a non-conjugated diene molecular weight regulator is used, more preferably when an allene compound is used.

  The polymerization reaction may be either a batch type or a continuous type, and the polymerization temperature is usually in the range of 0 to 100 ° C., preferably 10 to 60 ° C., and the polymerization pressure is usually in the range of 0 to 5 atm (gauge pressure). . After completion of the reaction, a polymerization terminator such as alcohol, an anti-aging agent, an antioxidant, an ultraviolet absorber, etc. are added to the reaction mixture, and then the produced polymer is separated, washed and dried according to a conventional method to obtain the desired polybutadiene. I can do it.

Rubber composition The rubber composition of the present invention is used by mixing with a rubber compounding agent usually used in the rubber industry, using the cis-1,4-polybutadiene rubber. As the rubber component, the cis-1,4-polybutadiene rubber alone or a combination of the cis-1,4-polybutadiene rubber and another diene rubber is used, and the cis-1,4-polybutadiene rubber in the rubber component is used. The proportion of the polybutadiene rubber is at least 10% by weight of the total rubber component, preferably 20% by weight or more, and more preferably 30% by weight or more. If the use ratio of the cis-1,4-polybutadiene rubber of the present invention is excessively small, the effect of the present invention is not sufficiently exhibited, which is not preferable.

  Other diene rubbers used in combination include, for example, natural rubber (NR), polyisoprene rubber (IR), emulsion polymerized styrene-butadiene copolymer rubber (SBR), solution polymerized random SBR (bonded styrene 5 to 50% by weight, butadiene 1,2-bond amount of unit part 10-80%), high trans SBR (1,4-trans bond amount 70-95% of butadiene unit part), low cis polybutadiene rubber (BR), high trans BR (butadiene unit) 1,4-trans bond amount of 70 to 95%), styrene-isoprene copolymer rubber (SIR), butadiene-isoprene copolymer rubber, solution polymerization random styrene-butadiene-isoprene copolymer rubber (SIBR), emulsion polymerization SIBR, emulsion polymerization styrene-acrylonitrile-butadiene copolymer rubber, acrylonitrile- Tajien copolymer rubber, high vinyl SBR- low vinyl SBR block copolymer rubber, polystyrene - polybutadiene - block copolymers such as polystyrene block copolymer. Can be appropriately selected according to the required characteristics. NR, IR, SBR, SIBR and the like are preferable, and NR, IR and the like are particularly preferable from the viewpoint of workability. These diene rubbers can be used alone or in combination of two or more.

  The particularly preferred composition of cis-1,4-polybutadiene rubber and other diene rubbers is the cis-1,4-polybutadiene rubber / natural rubber or synthetic isoprene rubber (weight composition ratio is 10/90 to 90/10, preferably 20/80 to 70/30) and the cis-1,4-polybutadiene rubber / natural rubber or synthetic isoprene rubber / styrene-butadiene copolymer rubber (weight composition ratio 80 to 20/10 to 70/10 to 70) Etc.

  Examples of the rubber compounding agent include a reinforcing agent, an extending oil, and a vulcanizing agent. Reinforcing agents include various grades of carbon black (SAF, ISAF, ISAF-HS, ISAF-LS, HAF, HAF-HS, HAF-LS, FEF, etc.), silica, etc., and are appropriately selected according to the intended use. The The amount of the reinforcing agent used is usually 20 to 150 parts by weight, preferably 30 to 120 parts by weight, and more preferably 40 to 100 parts by weight per 100 parts by weight of the raw rubber. If the amount of the reinforcing agent is excessively small, the reinforcing effect is small, and the tensile strength, wear resistance, and the like are decreased. On the other hand, if the amount is excessively large, the resilience and heat generation are decreased.

  As the extender oil, an extender oil such as paraffinic, naphthenic, or aroma-based oil is selected according to the application. The amount of the extender oil used is usually 1 to 150 parts by weight, preferably 2 to 100 parts by weight, more preferably 3 to 60 parts by weight per 100 parts by weight of the raw rubber. If the amount of the extender oil used is too small, the effect of dispersing the reinforcing agent is not sufficient, and if too large, the tensile strength, wear resistance and the like are deteriorated.

  The vulcanizing agent is mainly composed of sulfur, and other peroxides and sulfur donors can be used. The vulcanizing agent is usually used in the range of 0.05 to 5 parts by weight per 100 parts by weight of the raw rubber, but when the vulcanizing agent is sulfur, the range of 1 to 3 parts by weight per 100 parts by weight of the rubber is preferable.

  The rubber composition of the present invention can further use various rubber compounding chemicals as necessary. These rubber compounding chemicals include vulcanization aids such as stearic acid and zinc white, vulcanization accelerators of various systems such as sulfenamide, thiuram and guanidine, fillers such as calcium carbonate and talc, amines There are various compounding agents such as anti-aging agents, phenolic anti-aging agents, anti-ozone degradation agents, processing aids, tackifiers, waxes and the like. It is used in the range of 05 to 10 parts by weight.

  The rubber composition of the present invention is produced by blending and mixing the above components with a known rubber kneading machine such as a roll or a Banbury mixer.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the part and% in an Example are a basis of weight unless there is particular notice. Further, various measurements in the examples followed the following methods.

  The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using gel permeation chromatography of HLC-8020 manufactured by Tosoh Corporation, in parallel with two columns; GMH-XL (manufactured by Tosoh Corporation), column temperature; 40 Measured under measurement conditions of ° C., eluent: tetrahydrofuran, eluent flow rate: 1.0 ml / min, sample concentration 8 mg / 20 ml (tetrahydrofuran), and calculated as a standard polystyrene equivalent value. The amount of cis 1,4-bond was calculated by the Morero method using an IR spectrophotometer of IR-700 manufactured by JASCO Corporation to perform infrared absorption spectrum measurement. Mooney viscosity (ML1 + 4,100 ° C.) is the value after 4 minutes after preheating for 1 minute at 100 ° C. using an L-type rotor using an SMV-201 type Mooney machine manufactured by Shimadzu Corporation according to JIS K 6301. It was measured. The solution viscosity (SV) was a 5% styrene solution, and was measured at 30 ° C. using an Ostwald viscometer. The degree of branching is the same as that described above except that the gel permeation chromatography is combined with a multi-angle laser light scattering detector (DAWN F type) manufactured by Wyatt Technology and the sample concentration is 14 mg / 20 ml (tetrahydrofuran). The absolute molecular weight (Mi) and the mean square turning radius (Ri) are measured under the measurement conditions, the Z average value is calculated according to the above formula, and the Z mean mean square turning radius / Z average molecular weight (Rz / Mz) is obtained. It was.

Production Example 1
Two 250-liter stainless steel polymerization reaction vessels equipped with a stirrer, a cooling jacket and a reflux condenser were connected in series, and continuous polymerization was performed as follows. While flowing a mixed solution of benzene / 2-butene / 1,3-butadiene (10/70/20 wt%) through the pipe at a rate of 70 kg / h, 1,2-butadiene was 601 mmol / h and trimethyl orthoformate was 6 h / h. 0.1 mmol, 107 mmol of water was added per hour. While further adding 243 mmol / h (as a benzene solution) of diethylaluminum monochloride to this mixed solution, it was introduced into the polymerization reaction vessel. Cobalt octoate was added at 9.6 mmol / h from another pipe, and continuous polymerization was carried out for 120 hours at 20 ° C. and a residence time of 2 hours. The solution of cis-1,4-polybutadiene produced from the second reaction vessel was continuously withdrawn, and methanol was added to stop the polymerization reaction. After adding 0.5% by weight of 4-hydroxymethyl-2,6-di-t-butylphenol to the resulting polymer, the cis-1,4-polybutadiene rubber was coagulated and recovered by steam stripping. The polymer 1 was obtained by drying with hot air at 80 ° C. for 1 hour. The characteristic values of Polymer 1 are shown in Table 1.

Production Examples 2-6
According to the reaction conditions shown in Table 1, polymers 2 to 6 were produced according to Production Example 1. The characteristic values of these polymers are shown in Table 1.

From Table 1, it can be seen that a polymer having Mw / Mn of 2.5 or less and Rz / Mz of 60 × 10 ⁻¹² m · mol · kg ⁻¹ or more can be obtained by the polymerization conditions of this example. . On the other hand, when the amount of water is small, the molecular weight distribution is widened (Comparative Example 4), when the amount of trimethyl orthoformate is small, the molecular weight distribution is widened and the Rz / Mz ratio is small (Comparative Example 5), and 1,2- It can be seen that the Rz / Mz ratio becomes small when the amount of butadiene is small (Comparative Example 6). Further, when comparing the relationship between the solution viscosity (SV) / Mooney viscosity (ML) ratio and the Rz / Mz ratio, the SV / ML is higher in the polymer 1 (120/35 = 3.57) than in the polymer 3 (80/33 = 2.42), but Rz / Mz is larger for polymer 3 and the relationship is reversed. Polymer 5 also has a large SV / ML ratio (130/41 = 3.17) but small Rz / Mz.

Production Example 7
Polymer 7 was obtained in the same manner as in Production Example 1 except that 1,5-cyclooctadiene was used in place of 1,2-butadiene as the molecular weight regulator and the addition amount was tripled to 1800 mmol per hour. Polymer characteristic values of polymer 7 are as follows: cis-1,4-bond amount: 96.8%, Mooney viscosity (ML1 + 4, 100 ° C.); 38, solution viscosity; 113, Mw; 48 × 10 ⁴ , Mw / Mn; 2 .3, Rz / Mz; 63 × 10 ⁻¹² m · mol · kg ⁻¹ .

Test example 1
Using the cis-1,4-polybutadiene rubber produced in Production Examples 1 to 6 as a raw rubber, mixing sulfur of the following formulation and a compounding agent other than a vulcanization accelerator in a 250 ml Banbury mixer, The blended rubber composition was prepared by mixing the resulting mixture with sulfur and a vulcanization accelerator using a roll. Each obtained compounded rubber composition was press vulcanized at 160 ° C. for 15 minutes to prepare a test piece for evaluation.

Formulation (part)
Polymer 1-6 100
Stearic acid 2
Zinc Hana No. 1 3
HAF carbon 50
Aroma oil 5
Antioxidant (1) 1
Sulfur 1.5
Vulcanization accelerator (2) 1.1
(1) N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (2) N-cyclohexyl-2-benzothiazylsulfenamide

  The tensile strength was performed according to JIS K6301. The impact resilience was measured at 60 ° C. using a Lübke-type impact resilience tester according to JIS K6301. The exothermic property (HBU) was measured at 100 ° C. for 25 minutes under the conditions of a strain of 0.175 inch and a load of 25 pounds using a Goodrich flexometer according to ASTM D623. HBU is the temperature at which the vulcanizate generates heat when continuously strained, and the smaller this value, the better. Abrasion resistance was measured using a pico abrasion tester according to ASTM D2228. These characteristics were expressed as an index with the polymer 4 polymer being 100. The extrusion processability was performed using a garbage die in accordance with ASTM D2230, with the die and head set at 100 ° C., and the number of rotations varied depending on the blending conditions. The extrusion length indicates the length of the formulation that emerges over time, and the die swell indicates how much the formulation cross-sectional area has expanded from the cross-sectional area of the original die. A large value for the extrusion length and a small value for the die swell are excellent. The roll wrapping property is indicated by ◎ when the roll is wound neatly, ◯ when the roll is almost neatly wound, Δ when the roll is wound frequently but is lifted, and x when the roll is hardly wound. The above evaluation results are shown in Table 2.

  From Table 2, the examples of the present invention have improved roll wrapping property, extrusion length, and workability with respect to die swell, and further improved all vulcanized rubber properties such as strength properties, rebound resilience, heat buildup and wear resistance. I understand that.

Test example 2
Except that the raw material rubber used was a blend of polymer 1 and natural rubber in the proportions shown in Table 3, it was carried out in the same manner as in Test Example 1, and the compounded rubber properties and vulcanized rubber properties were evaluated. The results are shown in Table 3.

  From Table 3, when natural rubber is blended with polymer 1, roll wrapping property, extrusion length and workability with respect to die swell are remarkably improved without substantially impairing resilience and wear resistance, and heat generation is also remarkably improved. I understand that Moreover, it turns out that the example of this invention is excellent in the balance of workability, an intensity | strength characteristic, impact resilience, exothermic property, and abrasion resistance rather than the single use of the polymer 1 and natural rubber.

Test example 3
The combined system of the cis-1,4-polybutadiene rubber and natural rubber of the present invention was changed to the following compounding recipe, and the others were carried out in the same manner as in Test Example 2, and the compounded rubber characteristics and vulcanized rubber properties were evaluated. The results are shown in Table 4.

Formulation (part)
Natural rubber 40
Polymer 1-6 60
Stearic acid 2
Zinc Hana No. 1 3
FEF carbon 50
Aroma oil 10
Antioxidant (1) 1
Sulfur 1.5
Vulcanization accelerator (2) 0.8
(1) N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine
(2) Nt-butyl-2-benzothiazyl sulfenamide

Test example 4
Except changing to the following compounding prescription, it carried out similarly to Test Example 3, and evaluated the rubber composition characteristic and the physical property of vulcanized rubber. The results are shown in Table 5.

Formulation (part)
Natural rubber 70
Polymer 1-6 30
Stearic acid 2
Zinc Hana No. 1 3
ISAF Carbon 50
Aroma oil 10
Antioxidant (1) 1
Sulfur 1.5
Vulcanization accelerator (2) 1.1
(1) N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (2) N-cyclohexyl-2-benzothiazylsulfenamide

Claims (2)

The weight average molecular weight (Mw) measured by gel permeation chromatography is 100,000 to 1,000,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.5 or less, And a cis-1,4-polybutadiene rubber having a ratio (Rz / Mz) of Z average mean square turning radius (Rz) to Z average absolute molecular weight (Mz) of 50 × 10 ⁻¹² m · mol · kg ⁻¹ or more. A rubber composition for tires, which is contained in a total rubber component of 10% by weight or more.   A tire comprising the rubber composition for a tire according to claim 1.