JPH0359931B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a highly resilient high hardness rubber composition containing polybutadiene having a specific average chain length of 1,4 bonds, and a solid golf ball using the same. High-hardness rubber compositions as main components and solid golf balls using them, especially when used in the core material of multilayer golf balls such as one-piece golf balls or two-piece golf balls, achieve significantly superior ball initial velocity. The present invention relates to a high hardness rubber composition for golf balls and a solid golf ball using the same. Recently, since synthetic polymer substances have begun to be actively used as materials for golf balls, solid balls have come to occupy a larger proportion of the structure of golf balls, rather than wound balls. The performance of these golf balls includes flight distance, controllability, durability, and feel at impact, but in particular, it is important to increase the flight distance at high hitting speeds, that is, to improve the ball's rebound resilience and increase the initial velocity of the ball. Improving this is an important challenge for ball design technology. In response to these demands, polybutadiene rubber compositions have been used by taking advantage of their high resilience, but there has been a desire to further improve the resilience in the high impact speed range. As a result of intensive research aimed at improving resilience in the high impact speed range, the present inventors discovered that polybutadiene rubber with 1,4 bonds of a specific average chain length provides a rubber composition with excellent resilience. , arrived at the present invention. According to the invention, the cis-1,4 bond content is at least 80% and the average chain length of the 1,4 bonds is 110%.
A rubber composition consisting of 50 to 100 parts by weight of the above polybutadiene rubber and 50 to 0 parts by weight of other diene rubbers, a crosslinking monomer, an inorganic filler, and an organic peroxide as essential components in the high impact speed range. A vulcanizable high hardness rubber composition with excellent resilience is provided. The average chain length of 1,4 bonds defined in the present invention is determined as follows. That is, the hydrogenated product of polybutadiene of the present invention to be subjected to measurement is hydrogenated polybutadiene by HJ Harwood, Makromol, Chem., 163, 1.
(1973) by complete hydrogenation with p-toluenesulfonyl hydrazide. Complete hydrogenation is confirmed by ^H1 -NMR.
Hydrogenated polybutadiene was processed using JEOL Ltd. FX-100.
Measurement is performed using a type NMR device under the following conditions. Sample concentration: 300 mg/2 ml, 1,2,4-trichlorobenzene, 10 mmφ ¹³ C-NMR probe used, observation frequency: 25.05 MHz, internal lock method observation pulse width: 45° 6 μsec, pulse repetition time: 5.0 sec, spectral width : 2KHz, measurement temperature: 125℃, internal standard: HMDS, number of integrations: 110 x 100 to 190 x 100 times, and analysis by JCRandall, J.Polym.Sci.
It is carried out according to the method described in Polymer Physics Edition 13 , 1975 (1975). 1,2 bond average chain length = 2I ₅ +2I ₆ +I ₈ /I ₅ +I ₈ 1,4 bond average chain length = 8I ₉ +5I ₁₀ +2I ₁₁ /8I ₉ +4I _10Here , I ₅ , I ₆ , I ₈ , I ₉ , I ₁₀ , I ₁₁ have chemical shifts of 37.2, 34.8, 34.0, 31.0, 30.5, respectively.
This is the area intensity of the 30.0ppm peak.

【table】

[Table] Furthermore, the heat of fusion of the polybutadiene hydrogenation product of the present invention corresponds to the average chain length of 1,4 bonds, and is preferably 42 Cal/g or more. This is measured using a differential scanning calorimeter (DSC, manufactured by Rigaku Denki Co., Ltd.) by placing approximately 10 mg of hydrogenated polybutadiene in an aluminum measuring dish and increasing the temperature at a rate of 10°C/min. Determine the amount of heat from the melting peak area. If the heat of fusion is less than 42 Cal/g, the average chain length of 1,4 bonds will not exceed 110. The cis-1,4 bond content is determined using a nuclear magnetic resonance apparatus. The polybutadiene rubber containing 1,4 bonds with a specific average chain length used in the present invention is preferably a lanthanum series rare earth element compound (hereinafter referred to as Ln compound), an organoaluminium compound, and a catalyst comprising a combination of a Lewis acid and a Lewis base. It can be produced by polymerizing butadiene in the presence of. As the Ln compound, metal halides, carboxylates, alcoholates, thioalcoholates, amides, etc. having an atomic number of 57 to 71 are used. As organic aluminum, the general formula AlR ₁ R ₂
R ₃ (here, R ₁ to _{R 3} are hydrogen or C ₁ to _{C 3} hydrocarbon groups, and the number of hydrogen atoms is limited to 2 or less, and R ₁ to R ₃ may be the same, may also be different) is used. Lewis acids have the general formula AlXnR _3-o (where,
X is a halogen, R is a hydrocarbon residue,
Aluminum halides or other metal halides with n=1, 1.5, 2, 3 are used. Lewis bases are used to solubilize Ln compounds in organic solvents, and suitable examples include acetylacetone and ketones. The ratio of butadiene/Ln compound is 5×10 ² to 5×10 ⁶ in molar ratio, preferably
It is in the range of 10 ³ to 10 ⁵ . The ratio of AlR ₁ R ₂ R ₃ /Ln compound is 5 to 500 in molar ratio,
Preferably it is 10-300. The halide/Ln compound ratio in the Lewis acid ranges from 1.0 to 10, preferably from 1.5 to 5 in molar ratio. The molar ratio of Lewis base/Ln compound is 0.5 or more, preferably 1 to 20. The method for producing the above catalyst is detailed in Japanese Patent Application No. 56-99684. The above Ln compound catalyst can be used in the polymerization of butadiene in a state dissolved in a solvent or supported on silica, magnesia, magnesium chloride, etc. In the polymerization, a solvent may be used or bulk polymerization may be performed without using a solvent. The polymerization temperature is usually -30°C to 150°C, preferably 10 to 80°C, and the polymerization pressure can be arbitrarily selected depending on the conditions. In the present invention, the average chain length of 1,4 bonds is 110
The above is preferably 110 to 530, more preferably 130 to
530 range. If it is smaller than 110, there will be no improvement effect on resilience or initial velocity. The polybutadiene rubber of the present invention can also be obtained by mixing two or more polybutadienes having different average chain lengths of 1,4 bonds. In addition, cis-1 of the polybutadiene rubber of the present invention,
4 bond content is at least 80%, preferably 90%
That's all. If the cis-1,4 bond content is less than 80%, the resilience improving effect disappears. The Mooney viscosity of polybutadiene is not particularly limited, but
ML ₁₊₄ (100°C) 20-150 is preferred. Examples of diene rubbers other than polybutadiene rubber used in the present invention include natural rubber, polyisoprene rubber, and styrene-butadiene copolymer rubber. In the rubber composition of the present invention, the blend ratio of the polybutadiene rubber and other diene rubber is 50 to 100 parts by weight to 50 to 0 parts by weight, preferably 80 to 100 parts by weight.
~100 parts by weight vs. 20~0 parts by weight The sum of both is 100 parts by weight. If the polybutadiene rubber is less than 50 parts by weight, the effects of improving resilience and initial velocity will not reach a practical level. The high-hardness rubber composition of the present invention is a rubber composition obtained by blending a crosslinkable monomer, an inorganic filler, and an organic peroxide as essential components with a composition of the above-mentioned polybutadiene rubber and other diene rubber. According to the present invention, a high hardness rubber composition having excellent resilience in a high impact speed region can be obtained. The crosslinkable monomer used in the present invention includes:
It is usually an α,β-ethylenically unsaturated monocarboxylic or dicarboxylic acid or a monoester of a dicarboxylic acid. Specifically, acids such as methacrylic acid, acrylic acid, ethacrylic acid, cinnamic acid, crotonic acid, sorbic acid, maleic acid, phthalic acid and itaconic acid, and dicarboxylic acids (i.e. maleic acid, itaconic acid and phthalic acid). It is a monoester of Preferred is methacrylic acid. This amount is preferably 10 to 50 parts by weight per 100 parts by weight of the polymer. The inorganic filler used in the present invention is a compound that neutralizes the carboxylic acid groups present in the polymerizable crosslinkable monomer, and has the function of forming a metal ion bond and controlling the weight of the crosslinked product. Examples include titanium oxide, zinc oxide, iron oxide, aluminum oxide, calcium oxide, calcium hydroxide, and zinc carbonate, with zinc oxide being preferred. The amount of the inorganic filler blended is preferably 20 to 80 parts by weight per 100 parts by weight of the polymer. The part of the inorganic filler that plays a role in controlling the weight of the crosslinked material is a known filler such as barium sulfate, silica,
Clay, calcium carbonate or other metal compounds, carbon black, or mixtures thereof may be substituted. Organic peroxides added as crosslinking agents for crosslinking and curing the mixed formulations of the present invention include dicumyl peroxide, 1,3-bis(t
-butylperoxyisopropyl)benzene,
1,1-bis(t-butylperoxy)-3,3,
Examples include 5-trimethylcyclohexane, and dicumyl peroxide is preferred. The amount of organic peroxide added is 0.5 per 100 parts by weight of polymer.
~8 parts by weight is preferred. As a method for obtaining a high hardness rubber from the composition of the present invention, that is, a composition consisting of polybutadiene, a crosslinkable monomer, an inorganic filler, and an organic peroxide, first, the polybutadiene and the inorganic filler are mixed in an open roll, a Banbury mixer, or a kneader. The mixture is mixed using an extruder or the like, and then a crosslinking monomer is added and thoroughly kneaded. Next, an organic peroxide is added to this mixture while kneading it on a roll to obtain a blend. The kneaded mixture is molded in a mold at a crosslinking temperature of 120° to 180°C and a crosslinking time of 5 to 45 minutes. The cross-linked and molded high-hardness rubber composition of the present invention has excellent resilience in the high impact speed range, so it can be suitably used in applications that take advantage of this feature, particularly as a material for solid golf balls. A solid golf ball using the high hardness rubber composition for golf balls of the present invention exhibited an initial velocity of 61.2 m/sec or more. This value is the maximum initial velocity of a conventional solid golf ball made of rubber.
It is excellent, exceeding 60.5m/sec by 0.7m/sec. The contribution to the increase in initial velocity is the increase in flight distance of the ball, which reaches about 7 to 10 meters.
In particular, this is a remarkable improvement in reducing the number of long-haul shots. Next, the present invention will be further explained with reference to examples, but the present invention is not limited thereto unless it goes beyond the gist of the present invention. Examples 1 to 5 In a sufficiently dried glass 5L autoclave,
Under nitrogen, 2.5 kg of cyclohexane was charged, then 0.5 kg of butadiene was charged, and the temperature was raised to 60°C. Polymerization was started by charging 138.9 mM of triethylaluminum, 2.31 mM of diethylaluminum bromide, and a reaction product of neodymium octate (0.926 mM) with acetylacetone (1.85 mM) in the presence of 0.1 g of butadiene and aging the catalyst in advance in a separate container. The conversion rate reached 100% after 2 hours of polymerization.
At this point, 5 ml of a methanol solution containing the antioxidant 2,6-di-tert-butyl-P-cresol was injected to stop the reaction. After steam stripping according to a conventional method, the product was dried on a hot roll at 110°C to obtain polybutadiene. This is sample No.4
shall be. Table 1 shows the average chain length of 1,4 bonds, microstructure and calorimetric measurements of various polybutadiene rubber samples. Polybutadiene rubber sample No. 1 in Table 1 is a uranium-catalyzed polybutadiene rubber manufactured by Anic in Italy. Sample No. 2 is Sample No. 1
and Sample No. 4 were dissolved in n-hexane to the same concentration (wt%), blended in a ratio of 1:4, and dried. Sample No. 5 is a sample
Sample No. 4 and Sample No. 6 were dissolved in n-hexane to the same concentration (% by weight), blended at a ratio of 1:4, and dried. Sample No.6
is polybutadiene rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name BR01). Sample No. 7 is polybutadiene rubber (manufactured by Ube Industries, Ltd., trade name Ubepol 150)
It is. Sample No. 8 is polybutadiene rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name BR02). Sample No. 9 is polybutadiene rubber (manufactured by Philips Chemical Company, trade name CIS-4 1203)
It is. Sample No. 10 is polybutadiene (Asahi Kasei)
Co., Ltd., product name DIENE 35NF). sample
No. 3 is sample No. 1 using the same operation as sample No. 2.
and Sample No. 4 were blended in a ratio of 4:6 and dried.

[Table] Compounding recipe (for one-piece golf ball) Polybutadiene rubber 100 (parts by weight) Zinc white 42 Methacrylic acid 20 Permil D 2.8 Manufactured by Nippon Oil & Fats Co., Ltd. (Dicumyl peroxide) Vulcanization conditions 150°C, 30 minutes Rubber compounding The vulcanized physical properties of the composition were measured and the results are shown in Table 2. In addition, in the case of formulation for two-piece golf balls,
The amount of zinc white used is 30 parts by weight for the large ball core and 50 parts by weight for the small ball core, but the characteristics of the present invention are not impaired in either formulation. In Table 2: (1) Hardness was measured according to JIS K6301. (2) Loss tangent (tan δ), which is an index of resilience in the high impact speed range, was determined using a viscoelastic spectrometer (RMS type, manufactured by Rheometrics). The smaller the value, the better. Resilience was measured using a Danlopt tripsomer. (3) Use the same rotating disc type as the one used by the USGA. Head type speed: 43.0±0.3 (m/sec) Examples 6 to 7 In Examples 6 to 7, the results of measurements with different types of diene rubber are shown in Table 3.

【table】

【table】

[Table] (2) Made by Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Scope of Claims] 1. 50 to 100 parts by weight of polybutadiene rubber containing at least 80% of the bonds forming the molecular chain as cis-1,4 bonds, and in which the average chain length of the 1,4 bonds is 110 or more. and 50 to 0 parts by weight of another diene rubber (the sum of both is 100 parts by weight), and 10 to 50 parts by weight of one or more selected from the following group as a crosslinking monomer: , inorganic filler
A high-hardness rubber composition for golf balls obtained by crosslinking and curing a rubber composition containing 20 to 80 parts by weight and an organic peroxide as essential components: α,β-ethylenically unsaturated monocarboxylic acid and α,β - Metal salts of ethylenically unsaturated monocarboxylic acids, and metal salts of α,β-ethylenically unsaturated dicarboxylic acids, monoesters of α,β-ethylenically unsaturated dicarboxylic acids, and α,β-ethylenically unsaturated dicarboxylic acids. . 2. High hardness according to claim 1, wherein the polybutadiene rubber is mainly composed of polybutadiene rubber obtained by polymerization in the presence of a lanthanum-based rare earth element compound catalyst. Rubber composition. 3 Obtained by polymerization in the presence of a lanthanum series rare earth element compound catalyst, containing at least 80% of the bonds forming the molecular chain as cis-1,4 bonds, and having an average chain length of the 1,4 bonds. A polymer composition consisting of 50 to 100 parts by weight of polybutadiene rubber having a molecular weight of 110 or higher and 50 to 0 parts by weight of another diene rubber (the sum of both is 100 parts by weight) is added as a crosslinking monomer from the following group: 10 or more selected types
A solid golf ball made by crosslinking and curing a rubber composition comprising 50 parts by weight of an inorganic filler, 20 to 80 parts by weight of an inorganic filler, and an organic peroxide as essential components: α,β-ethylenically unsaturated monocarboxylic acid and metal salts of α,β-ethylenically unsaturated monocarboxylic acids, α,β-ethylenically unsaturated dicarboxylic acids, monoesters of α,β-ethylenically unsaturated dicarboxylic acids, and α,β-ethylenically unsaturated dicarboxylic acids. Metal salts of acids.