JP2009011438A - Golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a rebound of a ball as a whole by using a material obtained by molding, under heat, a rubber composition having excellent resilience, as a component of the ball. <P>SOLUTION: The golf ball uses, as a ball component, a material molded under heat from a rubber composition of (a) a base rubber which includes a polybutadiene of at least 40% cis-1,4 structure, (b) an unsaturated carboxylic acid and/or a metal salt thereof, (c) an organic peroxide, and (d) a halogenated thiophenol, and/or a metal salt thereof, which is prepared by reacting using a polar solvent, then washing with water and drying. The material of exceptional resilience which is obtained by molding a rubber composition under applied heat serves as the component of the ball, and as a result, the ball as a whole has highly excellent rebound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a golf ball having excellent resilience.

  Conventionally, in order to impart excellent resilience to golf balls, the focus has been on one or more of the Mooney value, polymerization catalyst, solution viscosity, molecular weight distribution, and other indicators of polybutadiene used as a base rubber. (For example, Patent Document 1: Japanese Patent Laid-Open No. 2004-292667, Patent Document 2: US Pat. No. 6,818,705, Patent Document 3: Japanese Patent Laid-Open No. 2002-355336, Patent Document 4: JP 2002-355337 A, Patent Document 5: JP 2002-355338 A, Patent Document 6: JP 2002-355339 A, Patent Document 7: JP 2002-355340 A, Patent Document 8 : JP 2002-356581 A).

  For example, in Patent Document 1: Japanese Patent Application Laid-Open No. 2004-292667, polybutadiene having a Mooney viscosity of 30 to 42 and a molecular weight distribution (Mw / Mn) of 2.5 to 3.8 is disclosed. No. 6,818,705 describes polybutadiene having a molecular weight of 200,000 or more and a resilience index of 40 or more as a base rubber for golf balls.

  However, there are many users who demand a golf ball with a longer flight distance, and there has been a demand for the development of a golf ball with excellent resilience.

  In order to improve the resilience of the core, Patent Document 9: Japanese Patent Laid-Open No. 2-297384 discloses a technique for adding an organic sulfur compound to the core material. In addition, with respect to a method for producing an organic sulfur compound, a production method in which a solvent to be used is improved is disclosed (for example, Patent Document 10: JP-A-48-8739, Patent Document 11: JP-A-54-30127). .

  However, a golf ball having higher resilience than the golf ball using the core material has been demanded.

JP 2004-292667 A US Pat. No. 6,818,705 JP 2002-355336 A JP 2002-355337 A JP 2002-355338 A JP 2002-355339 A JP 2002-355340 A Japanese Patent Laid-Open No. 2002-356581 JP-A-2-297384 JP-A-48-8739 JP 54-30127 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a golf ball having excellent resilience.

  As a result of intensive studies to achieve the above object, the present inventor, as a result, forms a thermoformed product of a rubber composition containing a base rubber, an unsaturated carboxylic acid and / or a metal salt thereof, and an organic peroxide. When forming the golf ball, the base rubber contains (a) polybutadiene containing 40% or more of cis-1,4 structure, and (d) the raw material is reacted with the rubber composition in a polar solvent, Thereafter, by blending a specific halogenated thiophenol and / or metal salt thereof produced through a water washing step and a drying step, a heat-molded product of a rubber composition having excellent resilience is obtained, and such heat-molding is performed. The present invention has been completed by discovering that a golf ball having an object as a constituent element can be a golf ball having excellent resilience.

That is, the present invention provides the following golf balls.
[1] (a) a base rubber containing polybutadiene containing 40% or more of cis-1,4 structure, (b) an unsaturated carboxylic acid and / or a metal salt thereof, and (c) an organic peroxide (D) (d) A heat-molded product of a rubber composition containing a halogenated thiophenol and / or a metal salt thereof produced by reacting raw materials in a polar solvent and then undergoing a washing step and a drying step A golf ball characterized by being an element.
[2] The golf ball of [1], wherein the polybutadiene is a polybutadiene formed using a rare earth element-based catalyst.
[3] The golf ball according to [1] or [2], wherein the polybutadiene has a stress relaxation time (T ₈₀ ) defined as follows of 5.5 or less.
[Stress relaxation time ( _T80 )]
ML _{1 + 4} (100 ° C.) value (measured according to ASTM D-1646-96, Mooney viscosity measured at 100 ° C.) Immediately after the rotor rotation was stopped, the ML _{1 + 4} value was 80%. This is the time (seconds) required to decrease.
[4] The golf ball according to [3], wherein the polybutadiene has a stress relaxation time (T ₈₀ ) of 3.5 or less.
[5] The golf ball according to [3], [4] or [5], wherein a proportion of the polybutadiene having a stress relaxation time (T ₈₀ ) of 5.5 or less in the base rubber is 40% by mass or more.
[6] Any one of [1] to [5], wherein the polybutadiene having a stress relaxation time (T ₈₀ ) of 5.5 or less is a polybutadiene formed by terminal modification after polymerization using a rare earth element-based catalyst. The golf ball described in the item.
[7] The golf ball according to any one of [1] to [6], wherein (d) includes a step of washing with water to which a surfactant is added.
[8] The golf ball of any one of [1] to [7], wherein (d) is a zinc salt of pentachlorothiophenol.

  According to the golf ball of the present invention, a heat-molded product of a rubber composition having very excellent resilience is used as a constituent element, and therefore, the resilience of the entire ball is very excellent.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention includes the following components (a) to (d):
(A) a base rubber containing polybutadiene containing 40% or more of a cis-1,4 structure;
(B) an unsaturated carboxylic acid and / or a metal salt thereof;
(C) an organic peroxide;
(D) The raw material is reacted in a polar solvent, and then a thermoformed product of a rubber composition containing a halogenated thiophenol and / or a metal salt thereof produced through a washing step and a drying step is used as a constituent element. A golf ball characterized by the following.

  In the present invention, the base rubber includes polybutadiene containing 40% or more of cis-1,4 structure. Here, the cis 1,4 bond content of the polybutadiene is preferably 60% or more, more preferably 80% or more, still more preferably 90% or more, and most preferably 95% or more. The 1,2-vinyl bond content of the polybutadiene is preferably 2% or less, more preferably 1.7% or less, still more preferably 1.5% or less, and most preferably 1.3% or less. Is recommended. If the cis 1,4 bond content or the 1,2 vinyl bond content is out of the above range, the resilience may be lowered.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polybutadiene is preferably 20 or more and 80 or less, but is not particularly limited.

  The polybutadiene in the present invention is preferably a polybutadiene formed using a rare earth element-based catalyst from the viewpoint of resilience.

  Here, a known catalyst can be used as the rare earth element-based catalyst. For example, a catalyst comprising a combination of a lanthanum series rare earth element compound, an organoaluminum compound, an alumoxane, a halogen-containing compound, and a Lewis base as necessary. Can be used.

  Examples of the lanthanum series rare earth element compounds include metal halides having an atomic number of 57 to 71, carboxylates, alcoholates, thioalcolates, amides, and the like.

As the organoaluminum compound, for example, in AlR ¹ R ² R ³ (wherein, R ^1, R ² and R ³ may be the same or different, hydrogen or C1-8 each hydrocarbon residue Can be used.

  As said alumoxane, the compound which has a structure shown by following formula (I) or following formula (II) can be mentioned suitably. In this case, Fine Chemicals, 23, (9), 5 (1994), J. Am. Am. Chem. Soc. 115, 4971 (1993); Am. Chem. Soc. 117, 6465 (1995) may be used.

（式中、Ｒ⁴は、炭素数１〜２０の炭素原子を含む炭化水素基、ｎは２以上の整数である。）

(In the formula, R ⁴ is a hydrocarbon group containing a carbon atom having 1 to 20 carbon atoms, and n is an integer of 2 or more.)

Examples of the halogen-containing compound, AlX _n R _3-n (wherein, X is a halogen, R represents a hydrocarbon residue having 1 to 20 carbon atoms, for example, an alkyl group, an aryl group, an aralkyl group N represents 1, 1.5, 2 or 3), strontium halides such as Me ₃ SrCl, Me ₂ SrCl ₂ , MeSrHCl ₂ and MeSrCl ₃ , and others, silicon tetrachloride, four Metal halides such as tin chloride and titanium tetrachloride are used.

  The Lewis base can be used to complex a lanthanum series rare earth element compound, and examples thereof include acetylacetone and ketone alcohol.

  In the present invention, the use of a lanthanum series rare earth element compound, particularly the use of a neodymium catalyst using a neodymium compound, is a polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds. Are preferable from the viewpoint of obtaining excellent polymerization activity, and specific examples of these rare earth element-based catalysts include those described in JP-A No. 11-35633.

  Here, when butadiene is polymerized in the presence of a rare earth element-based catalyst, a solvent may be used, or bulk polymerization or gas phase polymerization may be performed without using a solvent. The polymerization temperature is preferably −30 ° C. to 150 ° C., more preferably 10 to 100 ° C.

  In addition, the polybutadiene in the present invention can be obtained as a terminal-modified polybutadiene by reacting a terminal modifier on the active terminal of the polymer subsequent to the polymerization using the rare earth element-based catalyst. This is preferable from the viewpoint of manufacturing a golf ball.

  As the terminal modifier, known compounds can be used, and for example, compounds described in the following (1) to (6) can be used.

^{_{(1) R 5 n M'X 4}} -n, M'X 4, M'X 3, R 5 n M '(- R 6 -COOR 7) 4-n or _{^{R 5 n M' (- R}} 6 - COR ⁷ ) _4-n (wherein R ⁵ and R ⁶ may be the same or different and each represents a hydrocarbon group containing 1 to 20 carbon atoms, R ⁷ is a carbon atom having 1 to 20 carbon atoms) Which may contain a carbonyl group or an ester group in the side chain, M ′ is a tin atom, silicon atom, germanium atom or phosphorus atom, X is a halogen atom, and n is an integer of 0 to 3 A halogenated organometallic compound, a halogenated metal compound or an organometallic compound)

  (2) heterocumulene containing Y = C = Z bond in the molecule (wherein Y represents a carbon atom, oxygen atom, nitrogen atom or sulfur atom, and Z represents an oxygen atom, nitrogen atom or sulfur atom) Compound

  (3) Hetero 3-membered ring compound containing the following bond in the molecule

（式中、Ｙは、酸素原子、チッ素原子又はイオウ原子を示す）

(In the formula, Y represents an oxygen atom, a nitrogen atom or a sulfur atom)

  (4) Halogenated isocyano compound

^{(5) R 8 - (COOH} ) m, R 9 (COX) m, R 10 - (COO-R 11), R 12 -OCOO-R 13, R 14 - (COOCO-R 15) m, or the following formula Carboxylic acid, acid halide, ester compound, carbonate compound or acid anhydride represented by

（式中、Ｒ⁸〜Ｒ¹⁶は、同一でも異なっていてもよく、炭素数１〜５０の炭素原子を含む炭化水素基、Ｘはハロゲン原子、ｍは１〜５の整数を示す）

(In formula, R < ⁸ > -R < ¹⁶ > may be same or different, The hydrocarbon group containing a C1-C50 carbon atom, X is a halogen atom, m shows the integer of 1-5.)

_{^{(6) R 17 l M "}} (OCOR 18) 4-l, R 19 l M" (OCOR 20 -COOR 21) 4-l, or a metal salt of a carboxylic acid represented by the following formula

（式中、Ｒ¹⁷〜Ｒ²³は、同一でも異なっていてもよく、炭素数１〜２０の炭素原子を含む炭化水素基、Ｍ”はスズ原子、ケイ素原子又はゲルマニウム原子、ｌは０〜３の整数を示す。）

(Wherein, R ¹⁷ to R ²³ may be the same or different, hydrocarbon group containing a carbon atom having 1 to 20 carbon atoms, M "is a tin atom, silicon atom or germanium atom, l is 0 to 3 Indicates an integer.)

  Specific examples of the terminal modifiers shown in the above (1) to (6) and the reaction method thereof include those described in, for example, JP-A Nos. 11-35633 and 7-268132, and the like. Can be mentioned.

  In the present invention, the polybutadiene is contained in the base rubber, and the proportion of the polybutadiene in the base rubber is 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass. % Or more, and may be 100% by mass. If the ratio is too small, the resilience may decrease.

In addition to the polybutadiene, the rubber compound that may be blended in the base rubber is not particularly limited. For example, a polybutadiene rubber having a stress relaxation time T ₈₀ exceeding 3.5 may be blended. Alternatively, styrene butadiene rubber (SBR), natural rubber, polyisoprene rubber, ethylene propylene diene rubber (EPDM) or the like may be blended. These may be used alone or in combination of two or more.

  Here, the Mooney viscosity of such a compounding rubber is preferably 80 or less and 20 or more, but is not particularly limited.

  As such a compounding rubber, a rubber synthesized with a Group VIII catalyst can be used. Specific examples of the Group VIII catalyst include the following nickel-based catalysts and cobalt-based catalysts.

  That is, as the nickel-based catalyst, for example, a one-component system such as nickel diatomaceous earth, a two-component system such as Raney nickel / titanium tetrachloride, and a three-component system such as nickel compound / organometallic / boron trifluoride etherate. The thing etc. can be mentioned. As the nickel compound, reduced nickel with support, Raney nickel, nickel oxide, nickel carboxylate, organic nickel complex salt, or the like is used. Examples of the organic metal include trialkylaluminum such as triethylaluminum, tri-n-propylaluminum, triisobutylaluminum, and tri-n-hexylaluminum, n-butyllithium, sec-butyllithium, tert-butyllithium, 1, Examples include alkyl lithium such as 4-dilithium butane, and dialkyl zinc such as diethyl zinc and dibutyl zinc.

  In addition, as cobalt-based catalysts, cobalt and its compounds include Raney cobalt, cobalt chloride, cobalt bromide, cobalt iodide, cobalt oxide, cobalt sulfate, cobalt carbonate, cobalt phosphate, cobalt phthalate, cobalt carbonyl, cobalt acetyl. Examples thereof include acetonate, cobalt diethyldithiocarbamate, cobalt anilinium nitrite, cobalt dinitrosilkyl chloride and the like. -Trialkylaluminum such as n-propylaluminum, triisobutylaluminum, tri-n-hexylaluminum, ethylaluminum sesquik Aluminum alkyl sesquichloride of chloride etc., can be preferably exemplified a combination of aluminum chloride and the like.

  When the polymerization is performed using the Group VIII-based catalyst, particularly a nickel-based catalyst or a cobalt-based catalyst, usually, the reactor is continuously charged together with a solvent and a butadiene monomer, for example, the reaction temperature is 5 to 60 ° C, A method of operating the reaction pressure so as to obtain the Mooney viscosity can be exemplified by appropriately selecting the reaction pressure within the range of atmospheric pressure to 70 atm.

Although there is no restriction | limiting in particular in the said polybutadiene, It is preferable that the stress relaxation time ( _T80 ) defined as follows is 5.5 or less.

[Stress relaxation time ( _T80 )]
ML _{1 + 4} (100 ° C.) value (measured according to ASTM D-1646-96, Mooney viscosity measured at 100 ° C.) Immediately after the rotor rotation was stopped, the ML _{1 + 4} value was 80%. This is the time (seconds) required to decrease.

The Mooney viscosity referred to in the present invention is an industrial viscosity index measured with a Mooney viscometer which is a kind of rotational plasticity meter, and ML _{1 + 4} (100 ° C.) is used as a unit symbol. M represents Mooney viscosity, L represents a large rotor (L type), 1 + 4 represents a preheating time of 1 minute, and a rotor rotation time of 4 minutes, which means a value measured at 100 ° C.

The T ₈₀ value of the polybutadiene is preferably 5.5 or less, more preferably 3.5 or less, still more preferably 3.0 or less, still more preferably 2.8 or less, and most preferably 2.5. The lower limit is 1 or more, preferably 1.5 or more. When the T ₈₀ value exceeds 3, the object of the present invention is not achieved. On the other hand, if the T ₈₀ value is too small, there may be a problem in workability.

  Examples of the unsaturated carboxylic acid as the component (b) include acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Acrylic acid and methacrylic acid can be particularly preferably used. Moreover, as a metal salt of unsaturated carboxylic acid, zinc salt of unsaturated fatty acids, such as zinc methacrylate and zinc acrylate, a magnesium salt, etc. can be mentioned, Especially zinc acrylate can be used conveniently.

  The amount of the component (b) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and the upper limit is preferably 60 parts by mass or less, more preferably 100 parts by mass of the base rubber. It is recommended that the amount be 50 parts by mass or less, more preferably 45 parts by mass or less, and most preferably 40 parts by mass or less. When the blending amount of the component (b) is too large, the heat-molded product of the rubber composition may become hard and unbearable feel may occur, and when it is too small, the resilience may decrease.

  As said (c) component, a commercial item can be used, for example, park mill D (made by Nippon Oil & Fats Co., Ltd.), perhexa C (made by Nippon Oils & Fats Co., Ltd.), Luperco 231XL (made by Atochem Co., Ltd.), etc. can be used. If necessary, two or more different organic peroxides may be mixed and used.

  As a compounding quantity of the said (c) component, Preferably it is 0.1 mass part or more with respect to 100 mass parts of said base rubber, More preferably, it is 0.3 mass part or more, As an upper limit, Preferably it is 5 mass parts or less. It is recommended that the amount be 4 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. If the blending amount is too large or too small, a suitable hardness distribution, that is, hit feeling, durability and resilience may be inferior.

From the viewpoint of further improving resilience, the rubber composition in the present invention is a halogen produced by reacting the following components (d) and (d) in a polar solvent, followed by a water washing step and a drying step. It is preferable to blend a modified thiophenol and / or a metal salt thereof.

  As such a halogenated thiophenol and / or a metal salt thereof, specifically, metal salts such as mono-, di-, tri-, tetra-, and penta-halogenated thiophenols, more specifically, Can include zinc salts such as pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, and parachlorothiophenol. These may be used alone or in combination of two or more. Among these, a zinc salt of pentachlorothiophenol can be preferably used.

  The halogenated thiophenol and / or metal salt thereof is produced by reacting raw materials in a polar solvent, and then undergoing a washing step and a drying step, and the polar solvent is not particularly limited, but dimethyl Examples include formamide and pyridine. Among them, dimethylformamide can be preferably used. Usually, when producing halogenated thiophenol, for example, pentachlorothiophenol raw material can be obtained by reacting hexachlorobenzene with sodium sulfide or sodium hydrosulfide, but it is not limited to these raw materials. Absent. In addition, when making a zinc salt of pentachlorothiophenol, it can be obtained by adding zinc chloride or the like to the pentachlorothiophenol produced as described above, but it is not limited to these raw materials. Absent.

  After the above reaction, the product is washed with water for the purpose of removing the synthesis solvent. In this case, it is preferable to use hot water of about 40 to 80 ° C. Furthermore, it is preferable to add a surfactant appropriately to the washing water. Examples of the surfactant include anionic and nonionic ionic surfactants and nonionic surfactants, but the present invention is not limited to the types of these surfactants. Among the surfactants, for example, alkylbenzene sulfonic acid or its sodium salt can be used. The amount added is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and most preferably 0.5% by mass or less, based on the total amount of water. Washing with water and / or surfactant is more effective when performed twice or more times, and the washing method is not particularly limited. For example, stirring washing in a water tank or washing by continuous treatment in a filter, etc. Is mentioned. Moreover, about a drying process, for example, performing at 100-150 degreeC for 2 to 12 hours, combining these conditions and pressure reduction conditions, etc., but it is not limited to these specific conditions.

  Thus, by producing the halogenated thiophenol and / or its metal salt through washing and drying steps of the synthesized product, this organic sulfur compound greatly contributes to the butadiene cross-linking structure of the rubber composition and rebounds. It is possible to further increase the performance.

  The amount of the component (d) is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, still more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the base rubber. The upper limit is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and still more preferably 3 parts by mass or less. If the amount is too large, the hardness of the heat-molded product of the rubber composition may become too soft. On the other hand, if the amount is too small, improvement in resilience may not be expected.

  The rubber composition in the present invention may further contain additives such as inorganic fillers and anti-aging agents. Examples of the inorganic filler include zinc oxide, barium sulfate, calcium carbonate and the like, and the blending amount thereof is preferably 5 parts by mass or more, more preferably 7 parts by mass with respect to 100 parts by mass of the base rubber. Or more, more preferably 10 parts by mass or more, most preferably 13 parts by mass or more, and the upper limit is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 45 parts by mass or less, and most preferably 40 parts by mass. It is recommended that: If the amount is too large or too small, it may not be possible to obtain an appropriate mass and suitable resilience.

  From the standpoint of increasing the resilience, the inorganic filler preferably contains 50% by mass or more of zinc oxide, more preferably 75% by mass or more, particularly 100% by mass (inorganic filler) And zinc oxide is preferably 100%).

  The average particle diameter of zinc oxide (by the air permeation method) is preferably 0.01 μm or more, more preferably 0.05 μm or more, particularly 0.1 μm or more, and the upper limit is preferably 2 μm or less, more preferably 1 μm or less. It is done.

  Moreover, as an anti-aging agent, 2,2'-methylenebis (4-methyl-6-t-butylphenol) (Noklak NS-6, manufactured by Ouchi Shinsei Chemical Co., Ltd.), 2,2'-methylenebis (4 -Ethyl-6-t-butylphenol) (NOCRAK NS-5, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and the like. The blending amount is preferably 0 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, and most preferably 0.2 parts by mass with respect to 100 parts by mass of the base rubber. As described above, the upper limit is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1 part by mass or less, and most preferably 0.5 parts by mass or less. Recommended from the point of view.

  The heat-molded product of the rubber composition in the present invention can be obtained by vulcanizing and curing the above-described rubber composition in the same manner as a known golf ball rubber composition. Examples of the vulcanization conditions include conditions carried out at a vulcanization temperature of 100 to 200 ° C. and a vulcanization time of 10 to 40 minutes.

  Regarding the heat-molded product of the rubber composition in the present invention, the hardness difference obtained by subtracting the JIS-C hardness at the center of the heat-molded product from the JIS-C hardness of the surface of the heat-molded product is preferably 15 or more, more preferably 16 More preferably, it is 17 or more, most preferably 18 or more, and the upper limit is preferably 50 or less, more preferably 40 or less. Adjusting the hardness in this way is preferable from the viewpoint of realizing a golf ball having both a soft feel and good resilience and durability.

  In addition, the heat-molded product of the rubber composition in the present invention was loaded with an initial load of 1275 N (130 kgf) from a state where an initial load of 98 N (10 kgf) was applied, even when applied to any of the golf balls described below. The amount of time deflection is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 2.8 mm or more, and the upper limit is preferably 6.0 mm or less, more preferably 5.5 mm or less, still more preferably Is recommended to be 5.0 mm or less, most preferably 4.5 mm or less. If the amount of deformation is too small, the feeling of hitting will worsen, and in particular, long shots that cause large deformation of the ball, such as a driver, may cause excessive spin and will not fly, while if too soft, the feeling of hitting will be dull and rebounded. May not be sufficient and will not fly, and crack durability due to repeated impacts may deteriorate.

  The golf ball of the present invention comprises the thermoformed product as a constituent element, and the mode of the ball is not particularly limited, and the one-piece golf ball in which the thermoformed product is directly applied to the golf ball, thermoformed A two-piece solid golf ball having a solid core as an object and a cover formed on the surface thereof; a three-piece or more multi-piece solid golf ball having a heat-molded object as a solid core and having two or more layers on the outside; Various forms such as a wound golf ball in which a heat-formed product is applied as a center core, and a multi-piece golf ball in which the heat-formed product is applied as an intermediate layer or an outermost layer surrounding a solid core can be adopted. Use as a solid core, two-piece solid golf ball, multi-piece solid It is preferred because it can utilize effectively the properties of the hot-molded product to Rufuboru.

  In the present invention, when the thermoformed product is a solid core, the diameter of the solid core is preferably 30.0 mm or more, more preferably 32.0 mm or more, still more preferably 35.0 mm or more, and most preferably 37.mm. It is recommended that the upper limit is 0 mm or more, preferably 41.0 mm or less, more preferably 40.5 mm or less, still more preferably 40.0 mm or less, and most preferably 39.5 mm or less.

  In particular, the diameter of the solid core of the two-piece solid golf ball is preferably 37.0 mm or more, more preferably 37.5 mm or more, still more preferably 38.0 mm or more, and most preferably 38.5 mm or more. It is recommended that the thickness be 41.0 mm or less, more preferably 40.5 mm or less, and still more preferably 40.0 mm or less.

  Further, the diameter of the solid core of the three-piece solid golf ball is preferably 30.0 mm or more, more preferably 32.0 mm or more, still more preferably 34.0 mm or more, most preferably 35.0 mm or more. It is recommended that the thickness be 40.0 mm or less, more preferably 39.5 mm or less, and still more preferably 39.0 mm or less.

  The specific gravity of the solid core is preferably 0.9 or more, more preferably 1.0 or more, still more preferably 1.1 or more, and the upper limit is preferably 1.4 or less, more preferably 1.3 or less, It is recommended that it is preferably 1.2 or less.

  In the case of forming a two-piece solid golf ball or a multi-piece solid golf ball using the thermoformed product of the present invention as a core, known cover materials and intermediate layer materials can be used, and specific examples of these cover materials or intermediate layer materials can be used. Examples thereof include thermoplastic or thermosetting polyurethane elastomers, polyester elastomers, ionomer resins, polyolefin elastomers, and mixtures thereof. In particular, thermoplastic polyurethane elastomers and ionomer resins can be preferably used. These may be used alone or in combination of two or more. Moreover, when forming the golf ball as the intermediate layer or the outermost layer surrounding the solid core from the thermoformed product of the present invention, known core materials, intermediate layer materials, and cover materials can be used.

  Commercially available products can be used as the thermoplastic polyurethane-based elastomer. For example, diisocyanates such as Pandex T7298, T7295, T7890, TR3080, T8295, T8290 (DIC Bayer Polymer Co., Ltd.) are aliphatic or Those that are aromatic and the like. On the other hand, when ionomer resin is used as a cover material, commercially available products are Surlyn 6320, 8120 (manufactured by DuPont, USA), High Milan 1706, 1605, 1855, 1601, 1601, 1557 (manufactured by Mitsui DuPont Polychemical). Etc. can be illustrated.

  Furthermore, a polymer such as a thermoplastic elastomer other than the above can be blended as an optional component in the cover material. Specific examples of the optional component polymer include polyamide-based elastomers, styrene-based block elastomers, hydrogenated polybutadiene, and ethylene-vinyl acetate (EVA) copolymers.

  The two-piece solid golf ball and the multi-piece solid golf ball can be manufactured by a known method. In the case of a two-piece or multi-piece solid golf ball, the heat-molded product is provided as a solid core in a predetermined injection mold, and in the case of a two-piece solid golf ball, the cover material is provided as a multi-piece solid golf ball. In the case of a ball, a known method of sequentially injecting the intermediate layer material and the cover material according to a predetermined method can be suitably employed. In some cases, the cover material can be manufactured by pressure molding.

  The thickness of the intermediate layer of the multi-piece solid golf ball is preferably 0.5 mm or more, more preferably 1.0 mm or more, and the upper limit is preferably 3.0 mm or less, more preferably 2.5 mm or less, still more preferably Is recommended to be 2.0 mm or less, most preferably 1.6 mm or less.

  On the other hand, the cover thickness is preferably 0.7 mm or more, more preferably 1.0 mm or more, and the upper limit is preferably 3.0 mm or less, regardless of whether the cover is a two-piece solid golf ball or a multi-piece solid golf ball. It is recommended that the thickness is 2.5 mm or less, more preferably 2.0 mm or less, and most preferably 1.6 mm or less.

  The golf ball of the present invention can be used in competition and comply with the golf rules, and can be formed with a diameter of 42.67 mm or more and a weight of 45.93 g or less. The upper limit of the diameter is preferably 44.0 mm or less, more preferably 43.5 mm or less, most preferably 43.0 mm or less, and the lower limit of the weight is preferably 44.5 g or more, particularly preferably 45.0 g or more. More preferably, it is 45.1 g or more, and most preferably 45.2 g or more.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

Examples 1 to 4 and Comparative Example 1
Each raw material was kneaded in a kneader with the composition shown in Table 1 below to prepare a rubber composition, and vulcanized at 160 ° C. for 20 minutes in a spherical mold to obtain a weight of 36.9 g at 39.2 mmφ. Core (spherical molded product) was obtained. In addition, it shows below for the detail of the manufacturing method of a pentachlorothiophenol zinc salt.

Dimethylformamide (solvent) ・ Sodium sulfide ・ 48 parts by mass is dissolved in 70 parts by mass, then hexachlorobenzene ・ 177 parts by mass is added, and pentachlorothiophenol (intermediate) is produced while stirring at 80 ° C. for 120 minutes. did. Next, 27 parts by mass of zinc chloride and 27 parts by mass of water were reacted with pentachlorothiophenol at 80 ° C. for 30 minutes to obtain a pentachlorothiophenol zinc salt. And the solvent was collect | recovered and the process of the following I and II was used.
I. Centrifugal dehydration II. Stir and wash pentachlorothiophenol zinc salt in a water tank filled with warm water to which 0.5% by mass of sodium dodecylbenzenesulfonate (surfactant) is added

  What repeated said I and II 5 times was made into "pentachlorothiophenol zinc salt A", and what did not use the washing | cleaning process of I and II was made into "pentachlorothiophenol zinc salt B".

  Thereafter, the pentachlorothiophenol zinc salts A and B were dried in an oven at 120 ° C. for 8 hours to obtain a pentachlorothiophenol zinc salt as a final target product.

  In addition, when the content of dimethylformamide (DMF) contained in pentachlorothiophenol zinc salt A and pentachlorothiophenol zinc salt B was measured by infrared absorption spectrum (measuring instrument FT-IR / manufactured by Shimadzu Corporation), B In DMF, an absorption spectrum peculiar to DMF was observed, whereas in A, it was hardly observed.

  The amount of deflection and initial velocity of the obtained core were measured according to the following criteria. The results are shown in Table 1 below.

The details of the above blending are as follows.
・ Polybutadiene rubber: Trade name “EC140” (manufactured by Firestone Polymer)
Polymerized with Nd catalyst Mooney viscosity "43"
T ₈₀ value “2.3” cis-1,4-structure “96%”
・ Polybutadiene rubber: Trade name “BR51” (manufactured by JSR)
Polymerized with Nd catalyst Mooney viscosity "39"
T ₈₀ value “5.0” cis-1,4-structure “96%”
・ Polybutadiene rubber: Trade name “BR60” (manufactured by POLIMER Srl)
Polymerized with Nd catalyst Mooney viscosity "57"
T ₈₀ value “4.6” cis-1,4-structure “98%”
・ Polybutadiene rubber: Trade name “BR01” (manufactured by JSR)
Polymerized with Ni-based catalyst Mooney viscosity "48"
T ₈₀ value “8.4” cis-1,4-structure “96%”
・ Peroxide: Dicumyl peroxide Product name “Park Mill D” (manufactured by NOF Corporation)
-Zinc oxide: Sakai Chemical Co., Ltd. average particle size 0.6 μm (air permeation method),
Specific surface area 3.5m ² / g (BET method)
・ Zinc acrylate: Nippon Shokubai Co., Ltd. ・ Zinc stearate: Trade name “Zinc stearate G” (manufactured by NOF Corporation)

Deflection amount Deflection amount (mm) when initial load 98N (10 kgf) is applied and final load 1275 N (130 kgf) is applied to the core.
The initial speed was measured with an initial speedometer of the same type as the core initial speed index authorized organization USGA, and the value of the ratio based on the value of Comparative Example 1 was expressed.

Claims (8)

  (A) a base rubber containing polybutadiene containing 40% or more of a cis-1,4 structure, (b) an unsaturated carboxylic acid and / or a metal salt thereof, (c) an organic peroxide, (d) ) The raw material is reacted in a polar solvent, and then a heat-molded product of a rubber composition containing a halogenated thiophenol and / or metal salt thereof produced through a washing step and a drying step is used as a constituent element. Golf ball.   The golf ball according to claim 1, wherein the polybutadiene is a polybutadiene formed using a rare earth element-based catalyst. The golf ball according to claim 1, wherein the polybutadiene has a stress relaxation time (T ₈₀ ) defined as follows of 5.5 or less.
[Stress relaxation time ( _T80 )]
ML _{1 + 4} (100 ° C.) value (measured according to ASTM D-1646-96, Mooney viscosity measured at 100 ° C.) Immediately after the rotor rotation was stopped, the ML _{1 + 4} value was 80%. This is the time (seconds) required to decrease. The golf ball according to claim 3, wherein the polybutadiene has a stress relaxation time (T ₈₀ ) of 3.5 or less. The golf ball according to claim 3, 4 or 5, wherein a proportion of the polybutadiene having a stress relaxation time (T ₈₀ ) of 5.5 or less in the base rubber is 40% by mass or more. The golf ball according to claim 1, wherein the polybutadiene having a stress relaxation time (T ₈₀ ) of 5.5 or less is a polybutadiene formed by terminal modification after polymerization using a rare earth element-based catalyst. .   The golf ball according to claim 1, wherein (d) includes a step of washing with water to which a surfactant is added.   The golf ball according to claim 1, wherein (d) is a zinc salt of pentachlorothiophenol.