JP4650027B2 - Rubber composition - Google Patents

Description

The present invention relates to a rubber composition for golf balls having excellent characteristics, such as tire outer members such as treads and sidewalls in tires, tire inner members such as carcass, belts, and beads, and anti-vibration rubbers, belts, hoses, and the like. It can also be used for industrial articles such as seismic isolation rubber and footwear such as men's shoes, women's shoes, and sports shoes.

  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.

  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 particular, high-cis polybutadiene having a relatively narrow molecular weight distribution and high molecular linearity (linearity) has excellent wear resistance, heat resistance, and impact resilience. Tcp / ML _{1 + 4} is used as an index of linearity of high-cis polybutadiene having the same molecular weight distribution. Tcp indicates the degree of molecular entanglement in the concentrated solution. The larger Tcp / ML _{1 + 4} , the smaller the degree of branching and the greater the linearity.

Golf balls are classified into thread-wound and solid. In the case of a solid center of a thread-wound ball or a solid ball, a monomer having an unsaturated bond such as an unsaturated carboxylic acid metal salt is blended as a co-crosslinking agent in a base rubber such as polybutadiene. A compound containing an oxide and a metal oxide is used.
Polybutadiene rubber used as a base rubber for golf balls is generally required to have high resilience and excellent processability. However, when Mooney viscosity is increased, resilience improves but processability deteriorates and molecular weight When the distribution is widened, the workability is improved, but the resilience is lowered.

  In order to achieve both workability and resilience, various attempts have been made to improve polybutadiene rubber. For example, JP-A-63-275356 (Patent Document 1), JP-A-2-177773 (Patent Document 2) and the like disclose polybutadiene rubber synthesized with a Ni-based catalyst having a high Mooney viscosity and a wide molecular weight distribution. It is disclosed. Japanese Patent Publication No. 6-80123 (Patent Document 3) discloses a method of blending a polybutadiene rubber having a low Mooney viscosity and a polybutadiene rubber having a high Mooney viscosity. However, a material having higher resilience and excellent workability is desired.

JP-A-7-268132 (Patent Document 4) discloses the use of a polybutadiene rubber having a cis content of 97% or more modified with a tin compound as a rubber base material for a golf ball.
However, compared with conventional high-cis polybutadiene, there has been a demand for further improvement in durability that does not change in crosslink density.

  Japanese Patent Laid-Open No. 2001-40040 (Patent Document 5) by the present inventors discloses a polybutadiene having an appropriate 1,2-content as a golf ball having a long flight distance.

JP-A 63-275356 JP-A-2-177773 Japanese Patent Publication No. 6-80123 JP 7-268132 A Japanese Patent Laid-Open No. 2001-40040

An object is to provide a rubber composition suitable for a golf ball having excellent roll processability while maintaining hardness and high resilience.

(A1) The content of cis-1,4 having a Mooney viscosity of 30 to 42 synthesized with a cobalt catalyst and a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 2.5 to 3.8 5 to 99 parts by weight of high-cis polybutadiene which is 95% or more, (A2) Mooney viscosity synthesized with a cobalt catalyst, 50 to 70, and molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 2. 95 to 1 part by weight of high cis polybutadiene having a cis-1,4 content of 95 to 3.8.
(A) is (A1) + (A2) and is 20 to 100 parts by weight, (B) is a high cis polybutadiene having a Mooney viscosity of 30 to 70 and a cis-1,4 content other than (A) of 95% or more. There are 80 to 0 parts by weight.
A golf ball composition comprising 10 to 50 parts by weight of a co-crosslinking agent based on 100 parts by weight of the base polymer (A) + (B).

The ratio (Tcp / ML) of 5% toluene solution viscosity (Tcp) and Mooney viscosity (ML) of the high cis polybutadiene of (A1) and (A2) is 2.0 to 5.0 and contains cis 1.4 The golf ball composition according to claim 1, wherein the amount is 95% or more.

3. The golf ball according to claim 1, wherein the high-cis polybutadiene (A1) has a weight average molecular weight (Mw) of 400,000 to 540,000 and a number average molecular weight (Mn) of 100,000 to 250,000. Composition.

3. The golf ball according to claim 1, wherein the high-cis polybutadiene (A2) has a weight average molecular weight (Mw) of 550,000 to 700,000 and a number average molecular weight (Mn) of 150,000 to 300,000. Composition.

The golf ball composition described above, wherein the high-cis polybutadiene synthesis catalyst (B) is nickel-based or neodymium-based, and the cis-1.4 content is 95% or more.

The rubber composition in the present invention is composed of a specific high-cis polybutadiene and a co-crosslinking agent, and provides a rubber composition suitable for a golf ball excellent in processability while maintaining high resilience at an appropriate hardness. The

The polybutadiene synthesized using the (A1) cobalt catalyst of the present invention has the following characteristics.
The Mooney viscosity is 30 to 42, preferably 35 to 40. When the Mooney viscosity is larger than the above range, roll processability is lowered, and when the Mooney viscosity is smaller than the above range, the impact resilience may be lowered.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 2.5 to 3.8, preferably 2.6 to 3.5, more preferably 2.6 to 3.2. It is. When the molecular weight distribution is larger than the above range, the impact resilience is lowered, and when the molecular weight distribution is smaller than the above range, roll workability may be deteriorated.

The ratio (Tcp / ML) of 5% toluene solution viscosity (Tcp) to Mooney viscosity (ML) is 2.0 to 5.0, preferably 2.0 to 4.0, more preferably 2.1 to 3.5.
When the Tcp / ML ratio is larger than the above range, the cold flow property of the base rubber is increased, and when the Tcp / ML ratio is smaller than the above range, the rebound resilience is decreased.

  The cis 1.4 content is preferably 95% or more, particularly preferably 97% or more. If the cis 1.4 content is less than or equal to the above, the resilience decreases, which is not preferable.

The polybutadiene synthesized using the (A2) cobalt catalyst of the present invention has the following characteristics.
The Mooney viscosity is 50 to 70, preferably 55 to 65. If the Mooney viscosity is 50 or less, the impact resilience is lowered, and if it is 70 or more, the roll workability is deteriorated.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 2.5 to 3.8, preferably 2.6 to 3.5, more preferably 2.6 to 3.2. It is. When the molecular weight distribution is larger than the above range, the impact resilience is lowered, and when the molecular weight distribution is smaller than the above range, roll workability may be deteriorated.

The ratio (Tcp / ML) of 5% toluene solution viscosity (Tcp) to Mooney viscosity (ML) is 2.0 to 5.0, preferably 2.0 to 4.0, more preferably 2.1 to 3.5.
When the Tcp / ML ratio is larger than the above range, the cold flow property of the base rubber is increased, and when the Tcp / ML ratio is smaller than the above range, the rebound resilience is decreased, which is not preferable.

The cis 1.4 content is preferably 95% or more, particularly preferably 97% or more. If the cis 1.4 content is less than or equal to the above, the resilience decreases, which is not preferable.

    Said polybutadiene can be manufactured with a cobalt-type catalyst. Examples of the cobalt-based catalyst composition include a catalyst system comprising a cobalt compound, a halogen-containing organoaluminum compound, and water.

  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 nate, ethyl acetoacetate cobalt, pyridine complexes and picoline complexes of cobalt salts, or ethyl alcohol complexes.

  Examples of the halogen-containing machine aluminum include trialkylaluminum, dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum sesquichloride, alkylaluminum sesquibromide, alkylaluminum dichloride, and the like.

  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.

The polybutadiene synthesized by the catalyst other than the (B) cobalt-based catalyst of the present invention has the following characteristics.
The Mooney viscosity is 30 to 70, preferably 30 to 60. When the Mooney viscosity is larger than the above range, roll processability is deteriorated.

The cis 1.4 content is preferably 95% or more, particularly preferably 97% or more. If the cis 1.4 content is less than or equal to the above, the resilience decreases, which is not preferable.
Said polybutadiene can be manufactured with catalysts other than a cobalt type.
Examples of the catalyst other than cobalt-based catalysts include nickel-based or neodymium-based catalysts.

Examples of the nickel-based catalyst include a catalyst system composed of a nickel compound-organoaluminum compound.

  Nickel compounds include nickel naphthenate, nickel formate, nickel octylate, nickel stearate, nickel citrate, nickel benzoate and nickel toluate, organic complex compounds such as nickel acetylacetonate, and alkylbenzene sulfonic acid. Examples thereof include nickel and nickel oxyborate.

  Of these, nickel octylate is preferable.

  Examples of organoaluminum compounds include halogen-containing aluminum compounds, trialkylaluminum compounds, and aluminoxane compounds obtained by reacting them with water.

  Examples of halogen-containing aluminum compounds include dialkylaluminum halides such as dialkylaluminum chloride and dialkylaluminum bromide, alkylaluminum sesquichloride such as alkylaluminum sesquichloride and alkylaluminum sesquibromide, alkylaluminum dihalides such as alkylaluminum dichloride and alkylaluminum dibromide Is mentioned.

  Specific examples of the compound include diethylaluminum monochloride, diethylaluminum monobromide, dibutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, dicyclohexylaluminum monochloride, diphenylaluminum monochloride.

Examples of the trialkylaluminum compound include triethylaluminum, trimethylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum.
Examples of the aluminoxane compound include aluminoxane obtained by reacting the above halogen-containing aluminum and trialkylaluminum with water.
These organoaluminum compounds may be used alone or in combination.

Examples of the neodymium catalyst include a catalyst system composed of a neodymium compound, an organoaluminum compound, and water.

Examples of neodymium compounds include chloride, bromide, nitrate, versatic acid (trade name of Shell Chemistry, carboxylate having a carboxyl group mainly bonded to a tertiary carbon atom), octylate, 2-ethyl Fatty acid salts such as hexanoate, naphthenate, acetate, trifluoroacetate, malonate, monoacetylacetonate, bisacetylacetonate, trisacetylacetonate, acetoacetate ethyl ester complex, halide tria Examples include a reelphosphine complex, a trialkylphosphine complex, an organic base complex such as a pyridine complex and a picoline complex, an ether complex such as a diethyl ether complex, a tetrahydrofuran complex, and a dioxane complex, or an ethyl alcohol complex.

  Of these, fatty acid salts such as versatic acid salts, octyl acid salts, naphthenic acid salts, and trifluoroacetic acid salts are preferable.

  Examples of the organoaluminum compound include a halogen-containing aluminum compound, an alkylaluminum hydride, a trialkylaluminum, and a reaction product of the above compound and water.

  Examples of halogen-containing aluminum compounds include dialkylaluminum halides such as dialkylaluminum chloride and dialkylaluminum bromide, alkylaluminum sesquichloride such as alkylaluminum sesquichloride and alkylaluminum sesquibromide, alkylaluminum dihalides such as alkylaluminum dichloride and alkylaluminum dibromide Is mentioned.

  Specific examples of the compound include diethylaluminum monochloride, diethylaluminum monobromide, dibutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, dicyclohexylaluminum monochloride, diphenylaluminum monochloride.

  Examples of the alkylaluminum hydride include dialkylaluminum hydride, alkylaluminum sesquihydride, and alkylaluminum dihydride.

  Specific examples of the compound include diethylaluminum hydride, diisobutylaluminum hydride, ethylaluminum sesquihydride, ethylaluminum dihydride, dicyclohexylaluminum hydride, and diphenylaluminum hydride.

  Examples of the trialkylaluminum compound include triethylaluminum, trimethylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum.

  Examples of the reaction product of the organoaluminum compound and water include alumoxane obtained by reacting trimethylaluminum, triethylaluminum, diethylaluminum monochloride, diethylaluminum monobromide, ethylaluminum sesquichloride and ethylaluminum dichloride with water. .

  The above organoaluminum compounds may be used alone or in combination of two or more.

An ionic compound comprising a non-coordinating anion and a cation may be used in combination with the catalyst system.
Examples of non-coordinating anions include tetra (phenyl) borate, tetra (fluorophenyl) borate, tetrakis (difluorophenyl) borate, tetrakis (trifluorophenyl) borate, tetrakis (tetra Fluorophenyl) borate, tetrakis (pentafluorophenyl) borate, tetrakis (3,5-bistrifluoromethylphenyl) borate and the like.

  On the other hand, examples of the cation include a carbonium cation, an oxonium cation, an ammonium cation, and a phosphonium cation.

  Specific examples of the carbonium cation include trisubstituted carbonium cations such as a triphenylcarbonium cation and a tris (substituted phenyl) carbonium cation. Specific examples of the tris (substituted phenyl) carbonium cation include tri (toluyl) carbonium cation and tris (dimethylphenyl) carbonium cation.

  Specific examples of the ammonium cation include dialkyl ammonium cations such as trimethyl ammonium cation, triethyl ammonium cation, tripropyl ammonium cation, and tributyl ammonium cation.

  Specific examples of the phosphonium cation include triarylphosphonium cations such as a triphenylphosphonium cation, a tri (methylphenyl) phosphonium cation, and a tri (dimethylphenyl) phosphonium cation.

  As the ionic compound, those arbitrarily selected and combined from the non-coordinating anions and cations exemplified above can be preferably used.

  Among these, as ionic compounds, triphenylcarbonium tetrakis (pentafluorophenyl) borate, triphenylcarbonium tetrakis (fluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate. And 1,1′-dimethylferrocenium tetrakis (pentafluorophenyl) borate are preferred. Of these, triphenylcarbonium tetrakis (pentafluorophenyl) borate is particularly preferable.

  An ionic compound may be used independently and may be used in combination of 2 or more type.

The base polymer of the present invention comprises (A) composed of (A1) 5-9 parts by weight of high cis polybutadiene and (A2) 95-1 parts by weight of high cis polybutadiene, and (B) high cis polybutadiene. can get. Preferably, it is obtained by blending 20 to 100 parts by weight of (A) and 80 to 0 parts by weight of (B) high-cis polybutadiene.

The rubber composition for golf balls of the present invention is characterized in that 10 to 50 parts by weight of a co-crosslinking agent is blended with 100 parts by weight of a base polymer containing polybutadiene having the above characteristics.

The co-crosslinking agent blended in the rubber composition is preferably a monovalent or divalent metal salt of an α, β-ethylenically unsaturated carboxylic acid. Specific examples thereof include, for example, zinc diacrylate, basic Examples include zinc methacrylate and zinc dimethacrylate. These metal salts of α, β-ethylenically unsaturated carboxylic acids are used in an acrylic composition in a rubber composition in which a metal oxide such as zinc oxide is kneaded in advance, in addition to the usual method of mixing with a base rubber as it is. An α, β-ethylenically unsaturated carboxylic acid such as acid or methacrylic acid is added and kneaded, and the α, β-ethylenically unsaturated carboxylic acid and the metal oxide are reacted in the rubber composition to obtain α, β. -It may be a metal salt of an ethylenically unsaturated carboxylic acid.

  The amount of the co-crosslinking agent is preferably 10 to 50 parts by weight with respect to 100 parts by weight of the base rubber. When the amount of the co-crosslinking agent is less than the above range, the crosslinking does not proceed sufficiently. As a result, the repulsion performance is lowered, the flight distance is reduced, and the durability is also deteriorated. On the other hand, when the amount of the co-crosslinking agent is greater than the above range, the compression feeling becomes too large and the shot feeling becomes worse.

  In the present invention, it is preferable that peroxides are blended as essential components in the rubber composition that constitutes the rubbery portion, in addition to the above-mentioned co-crosslinking agent.

  These peroxides act as initiators for crosslinking, grafting, and polymerization of rubber and co-crosslinking agents. Specific examples of suitable peroxides include dicumyl peroxide and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane.

  The blending amount of the peroxide is preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the base rubber. When the amount of heroxides is less than the above range, crosslinking or the like cannot be sufficiently progressed. As a result, the repulsion performance is lowered, the flight distance is reduced, and the durability is also deteriorated. Moreover, when the compounding quantity of peroxide exceeds more than the said range, since it becomes overcure (overcrosslinking) and becomes weak, durability will worsen.

When the co-crosslinking agent is zinc diacrylate or zinc dimethacrylate, the rubber composition may be blended with zinc oxide that also acts as a crosslinking aid, and if necessary, filled with barium sulfate or the like. You may mix | blend additives, such as an agent, antioxidant, and a zinc stearate.
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 JIS 6300, and the blend Mooney viscosity was evaluated by an index with Comparative Example 1 being 100. The smaller the index, the lower the viscosity and the better the workability.

  The roll processability was determined by winding the composition around a 6 inch roll at 50 ° C. and visually observing the wound state.

  The hardness was measured by a durometer type (type D) in accordance with a measurement method defined in JIS-K6253, and the evaluation was based on an index with Comparative Example 1 being 100. The higher the index, the higher the hardness.

  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, and the comparative example 1 was set to 100 and evaluated as an index. The larger the index, the higher the tensile strength and the better.

  The impact resilience was measured by a trypso method according to a measurement method defined in JIS-K6251 and evaluated as an index with Comparative Example 1 being 100. The larger the index, the better the rebound resilience.

(Examples 1-5, Comparative Examples 1-4)
A rubber composition was produced using the polybutadiene shown in Table 1. Table 2 shows the conditions and results.

Claims (3)

(A1) The content of cis-1,4 having a Mooney viscosity of 30 to 42 synthesized with a cobalt catalyst and a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 2.5 to 3.8 5 to 99 parts by weight of high-cis polybutadiene which is 95% or more , (A2) Mooney viscosity synthesized with a cobalt catalyst, 50 to 70, and molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 2. 95 to 1 part by weight of high cis polybutadiene having a cis-1,4 content of 95 to 3.8.
(A) is (A1) + (A2) and is 20 to 100 parts by weight, (B) is a high cis polybutadiene having a Mooney viscosity of 30 to 70 and a cis-1,4 content other than (A) of 95% or more. There are 80 to 0 parts by weight.
A golf ball composition comprising 10 to 50 parts by weight of a co-crosslinking agent based on 100 parts by weight of the base polymer (A) + (B). The ratio (Tcp / ML) of 5% toluene solution viscosity (Tcp) and Mooney viscosity (ML) of the high cis polybutadiene of (A1) and (A2) is 2.0 to 5.0 and contains cis 1.4 The golf ball composition according to claim 1, wherein the amount is 95% or more. 3. The golf ball according to claim 1, wherein the high-cis polybutadiene synthesis catalyst (B) is nickel-based or neodymium-based, and has a cis-1.4 content of 95% or more. Composition.