JP2005154754A - Oil-extended polybutadiene and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber material having low pollution, low fuel consumption, low heat generation and excellent low temperature characteristics.
SOLUTION: (A) An extension having a viscosity specific gravity constant (VGC) of 0.790 to 0.849 with respect to 100 parts by weight of a high-cis polybutadiene having a Mooney viscosity (ML) of 50 to 100. The molecular weight distribution ((weight average molecular weight (Mw) / number average molecular weight (Mn)) of the oil-extended polybutadiene characterized by containing 5 to 100 parts by weight of oil and the high-cis polybutadiene of (A) is 2. An oil-extended polybutadiene characterized by being 0-5.0.

Description

  The present invention relates to an oil-extended polybutadiene and rubber composition that is excellent in low fuel consumption, low heat generation, and low temperature characteristics, and is environmentally friendly, such as tire outer members such as treads and sidewalls in a tire, carcass belt bead, etc. It can also be used for tire inner members and industrial articles such as anti-vibration rubber, belts, hoses, and seismic isolation rubber, and footwear such as men's shoes, women's shoes, and sports shoes.

  Polybutadiene is 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.

  It is known that the above-mentioned polybutadienes having different microstructures are produced depending on the polymerization catalyst and polymerization conditions, and they are used in various applications depending on their properties.

In recent years, resource saving and environmental measures have been emphasized, and the demand for low fuel consumption has been increased in tire materials, and materials with low pollution have been demanded.
As a method of improving tensile strength, wear resistance, fuel efficiency, etc., the molecular weight of rubber is generally increased. However, if the molecular weight is increased, processability deteriorates. Proposals for exhibition rubber have been made.

    For example, Japanese Patent Application Laid-Open No. 7-292161 (Patent Document 1), Japanese Patent Application Laid-Open No. 2000-178378 (Patent Document 2), Japanese Patent Application Laid-Open No. 2000-281835 (Patent Document 3), and the like. In addition, a rubber composition having improved exothermic properties is disclosed.

In general, aromatic and naphthenic process oils are used as extender oils for oil-extended rubber, but these extender oils are suspected to be carcinogenic because of their high aroma carbon content and are less harmful to the environment. There is a need for materials.
Aromatic process oils have high rubber tensile strength but poor fuel economy (rebound resilience, tan δ) and heat build-up, especially in studless tires, which have the disadvantage of high elastic modulus (E ′) at low temperatures. .

JP 7-292161 A JP 2000-178378 A Japanese Unexamined Patent Publication No. 2000-281835

  An object of the present invention is to provide a rubber material having low pollution, low fuel consumption, low heat generation and low temperature characteristics.

  The present invention relates to (A) 100 parts by weight of high-cis polybutadiene having a Mooney viscosity (ML) of 50 to 120, and (B) an extension having a viscosity specific gravity constant (VGC) of 0.790 to 0.849. The present invention relates to an oil-extended polybutadiene containing 5 to 100 parts by weight of oil.

    In the present invention, the molecular weight distribution ((weight average molecular weight (Mw) / number average molecular weight (Mn)) of the high-cis polybutadiene (A) is 1.8 to 5.0. It relates to oil-extended polybutadiene.

    Further, the present invention is characterized in that the ratio of the 5% toluene solution viscosity (Tcp) of the high cis polybutadiene (A) to ML is 1.5 to 5.0 and the cis content is 95% or more. The above-mentioned oil-extended polybutadiene.

  The present invention also relates to the above oil-extended polybutadiene, wherein the aroma carbon content of the extender oil (B) is 10% or less.

    The present invention also relates to a rubber composition comprising 10 to 100 parts by weight of a rubber reinforcing agent based on 100 parts by weight of the rubber component containing the oil-extended polybutadiene.

  The oil-extended polybutadiene and rubber composition in the present invention is composed of a specific high-cis polybutadiene, a specific process oil and a rubber reinforcing agent, and is a rubber having low pollution, low fuel consumption, low heat generation and low temperature characteristics. Material provided

  The (A) high cis polybutadiene used in the present invention has the following characteristics.

The Mooney viscosity (ML) is 50 to 120, preferably 60 to 90.
When the Mooney viscosity is larger than the above range, the workability may be lowered, and when the Mooney viscosity is smaller than the above range, the wear resistance may be lowered.

    The molecular weight distribution ((weight average molecular weight (Mw) / number average molecular weight (Mn))) is preferably 1.8 to 5.0, particularly preferably 2.0 to 4.0.

When the molecular weight distribution is larger than the above range, the rebound resilience may be lowered, and when the molecular weight distribution is smaller than the above range, the workability may be lowered.

    The ratio between the 5% toluene solution viscosity (Tcp) and ML is preferably 1.5 to 5.0, particularly preferably 2.0 to 4.0.

    If the ratio of 5% toluene solution viscosity (Tcp) to ML is larger than the above range, the cold flow property may be lowered, and if it is smaller than the above range, the wear resistance may be lowered.

The cis content is preferably 95% or more, particularly preferably 97% or more.
When the cis content is smaller than the above range, the wear resistance may be lowered, which is not preferable.

  The above polybutadiene can be produced by polymerization using a transition metal compound catalyst system as a polymerization catalyst. Examples of transition metal compound catalyst systems include Ziegler-Natta catalysts such as cobalt-based catalyst compositions and nickel-based catalyst compositions, metallocene-based catalysts, and rare earth element catalysts.

  As the cobalt-based catalyst composition, a catalyst system comprising a cobalt compound, a halogen-containing organoaluminum compound and water, and as the nickel-based catalyst composition, a nickel-based catalyst composition comprising a nickel compound, an organoaluminum compound and a fluorine compound, Examples of the metallocene catalyst include a metallocene complex of a Group 5 transition metal compound in the periodic table, an ionic compound of a non-coordinating anion and a cation, an organoaluminum compound, and water. The rare earth element catalyst includes a composite catalyst system composed of a rare earth metal compound such as a neodymium compound and a group I to III organometallic compound such as an organoaluminum compound. Among these, a cobalt-based catalyst composition is preferable.

  As the cobalt compound, a cobalt salt or complex is preferably used. Particularly preferred are cobalt salts such as cobalt chloride, cobalt bromide, cobalt nitrate, cobalt octylate (ethylhexanoate), cobalt naphthenate, cobalt acetate and cobalt malonate, cobalt bisacetylacetonate and trisacetylacetate. Examples thereof include organic base complexes such as nates, ethyl acetoacetate cobalt, pyridine complexes and picoline complexes of cobalt salts, or ethyl alcohol complexes.

  Examples of the organic aluminum 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.

  In addition to butadiene monomers, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, conjugated dienes such as 2,4-hexadiene, Acyclic monoolefins such as ethylene, propylene, butene-1, butene-2, isobutene, pentene-1, 4-methylpentene-1, hexene-1 and octene-1, cyclic monoolefins such as cyclopentene, cyclohexene and norbornene; And / or an aromatic vinyl compound such as styrene and α-methylstyrene, a non-conjugated diolefin such as dicyclopentadiene, 5-ethylidene-2-norbornene, and 1,5-hexadiene.

  The polymerization method is not particularly limited, and bulk polymerization (bulk polymerization) using a conjugated diene compound monomer such as 1,3-butadiene itself as a polymerization solvent, or solution polymerization can be applied. Solvents used in the solution polymerization include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as n-hexane, butane, heptane and pentane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and the like. And olefinic hydrocarbons such as cis-2-butene and trans-2-butene, hydrocarbon solvents such as mineral spirit, solvent naphtha and kerosene, and halogenated hydrocarbon solvents such as methylene chloride. .

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

  The polymerization temperature is preferably in the range of -30 to 150 ° C, particularly preferably in the range of 30 to 100 ° C. The polymerization time is preferably in the range of 1 minute to 12 hours, particularly preferably 5 minutes to 5 hours.

  After performing the polymerization for a predetermined time, the inside of the polymerization tank is released as necessary, and post-treatment such as washing and drying steps is performed.

  In addition to the above high cis polybutadiene, low cis polybutadiene rubber (BR), emulsion polymerization or solution polymerization styrene butadiene rubber (SBR), natural rubber, polyisoprene rubber, ethylene propylene diene rubber (EPDM), nitrile rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR) or the like may be mixed.

  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 also be used. These rubbers can be used alone or in combination of two or more. May be.

  As the extending oil having a viscosity specific gravity constant (VGC) of 0.790 to 0.849 of the component (B) of the present invention, any extending oil or softening agent usually used for diene rubbers can be used. Although there is no restriction | limiting in particular, For example, a mineral oil type extending oil can be mentioned as a suitable example.

  Among these, as the extending oil satisfying the above-mentioned viscosity specific gravity constant, Diana Process Oil PW-32 (VGC = 0.807), PW-90 (VGC = 0.0.7) manufactured by Idemitsu Kosan Co., Ltd. 8021), PW-150 (VGC = 0.792), PS-430 (VGC = 0.91818), Syntactic PA-95 (VGC = manufactured by Kobe Oil Chemical Co., Ltd.) 0.811), PA-100 (VGC = 0.814), PA-140 (VGC = 0.794), JOMO process P200 (VGC = manufactured by Japan Energy) 0.8022), P300 (VGC = 0.8046), P500 (VGC = 0.8193), 750 (VGC = 0.8148), Nippon San Oil Thumper 110 (VGC = 0.811), 115 (VGC = 0.807) 120 (VGC = 0.802), 130 (VGC = 0.801), 150 (VGC = 0.803), 2100 (VGC = 0.804) ), 2280 (VGC = 0.794), Fukukor process P-100, P-200, P-300, P-400, P-500 manufactured by Fuji Kosan Co., Ltd., and the like.

The aroma carbon content of the extending oil is preferably 10% or less, particularly preferably 5% or less.
When the aroma content exceeds the above range, pollution is increased, which is not preferable.

The viscosity specific gravity constant (VGC value) is 0.790 to 0.849, preferably 0.790 to 0.819. If the viscosity specific gravity constant (VGC value) is out of the above range, the rebound resilience and heat build-up will be unfavorable.
The extending oil is sufficiently stirred so that the process oil used in the present invention is added to the polymerization system in which the polymerization reaction has been stopped by the reaction stopping step and is uniformly dispersed. In this case, if necessary, a compounding agent may be added at this step together with the process oil. When the polymer is heated in the solvent removal or drying step in the next step, it is preferable to add a phenol-based stabilizer, a phosphorus-based stabilizer, a sulfur-based stabilizer, etc. in the anti-aging agent in this step. What is necessary is just to determine the addition amount of an anti-aging agent according to the kind etc.

  Examples of rubber reinforcements include inorganic reinforcements such as various carbon blacks and white carbon, activated calcium carbonate, and ultrafine magnesium silicate, polyethylene resin, polypropylene resin, high styrene resin, phenol resin, lignin, modified melamine resin, and silicone. There are organic reinforcing agents such as malon indene resin and petroleum resin.

  Particularly preferred is carbon black having a particle size of 90 nm or less and a dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more, and examples thereof include FEF, FF, GPF, SAF, ISAF, SRF, and HAF.

  The mixing ratio of the oil-extended polybutadiene of the present invention is 5 to 100 parts by weight, preferably 10 to 60 parts by weight, based on 100 parts by weight of the specific high-cis polybutadiene.

  The mixing ratio of the rubber composition of the present invention is 10 to 100 parts by weight, preferably 30 to 80 parts by weight, based on 100 parts by weight of the rubber component containing the oil-extended polybutadiene.

  Examples according to the present invention will be specifically described below.

The microstructure 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 .

  The molecular weight (Mw, Mn) was measured by GPC method: HLC-8220 (manufactured by Tosoh Corporation) and calculated by standard polystyrene conversion.

  Toluene solution viscosity (Tcp) was obtained by dissolving 2.28 g of polymer in 50 ml of toluene, using a standard solution for calibrating viscometer (JIS Z8809) as a standard solution, and using a Canon Fenceke viscometer No. 400 was used and measured at 25 ° C.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the base rubber and the blend was measured according to JIS6300.

  The hardness was measured by a durometer type (type A) according to a measurement method defined in JIS-K6253.

  The tensile strength was measured with a No. 3 dumbbell at a tensile speed of 500 mm / min according to the measurement method defined in JIS-K6251.

  The impact resilience was measured by a trypso method according to a measurement method defined in JIS-K6251.

E ′ (−20 ° C.) and tan δ (60 ° C.) were measured using a rheometrics viscoelasticity measuring device at a frequency of 10 Hz and a dynamic strain of 0.05%. displayed. The smaller the index, the better.

(Examples 1-2, Comparative Examples 1-4)
A rubber composition was produced using the polybutadiene shown in Table 1. Tables 2 to 3 show conditions and results.

Claims (5)

(A) For 100 parts by weight of high-cis polybutadiene having a Mooney viscosity (ML) of 50 to 120, (B) an extension oil having a viscosity specific gravity constant (VGC) of 0.790 to 0.849 is 5 to An oil-extended polybutadiene containing 100 parts by weight. 2. The oil extension according to claim 1, wherein the molecular weight distribution ((weight average molecular weight (Mw) / number average molecular weight (Mn)) of the high-cis polybutadiene (A) is 1.8 to 5.0. Polybutadiene. The ratio of 5% toluene solution viscosity (Tcp) of the high cis polybutadiene (A) to ML is 1.5 to 5.0, and the cis content is 95% or more. Oil-extended polybutadiene as described in 1. The oil-extended polybutadiene according to claim 1, wherein the aroma carbon content of the extension oil (B) is 10% or less. A rubber composition comprising 10 to 100 parts by weight of a rubber reinforcing agent based on 100 parts by weight of a rubber component containing the oil-extended polybutadiene according to claim 1.