JPH0439866B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a coating composition for golf balls that has excellent durability, rebound resilience (flight characteristics), and feel when hit. (Prior Art) Golf balls are required to have flight stability, long-distance flight performance, etc., and these characteristics require well-controlled rebound resilience, compressive strength, hardness, etc. Although various proposals have been made to improve the quality of compositions, the major challenge is to improve the surface coating layer that comes into contact with direct current during impact, and various compositions based on ionomer resins have been proposed. The present inventors have already proposed an excellent rubber composition consisting of a combination of potassium titanate fibers and ionomer resin, and are currently applying for a patent (Japanese Patent Application No. 1983-202118). It has been found that the physical properties of rubber can be further improved by surface treatment of metal fibers. (Problems to be Solved by the Invention) An object of the present invention is to provide a coating composition for a golf ball that has high strength, high repulsion, and excellent feel when hit, and as a result, exhibits excellent flight distance. There is a particular thing. (Means for Solving the Problems) Fibrous titanium surface-treated with a surface treatment agent selected from mercapto group-containing silane compounds and silyl group-containing sulfide compounds represented by general formulas () and () described later in the present invention The present invention relates to a golf ball coating composition comprising one or a mixture of two or more of an acid alkali metal and a synthetic rubber and/or a natural rubber. Various known rubbers can be used as the rubber component of the present invention, such as natural rubber (NR),
Isoprene rubber (IR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), butadiene rubber (BR), chloropropylene rubber (CR), butyl rubber (IIR), acrylic rubber (AR), urethane rubber (UR), Silicone rubber (SiR), fluorocarbon rubber (FR), ethylene propylene rubber (EPR), chlorosulfonated polyethylene (CSM), ethylene acetate rubber (EVA), chlorinated polyethylene (CPE), polyisobutylene (PIB), Alfin rubber ( A.L.),
Examples include polyester rubber (ESR), epichlorohydrin rubber (ECR), chlorinated butyl rubber (CIR), nitrile isobutylene rubber (NIR), ionomer resin, transpolyisoprene resin, and the like. Among these rubber components, ionomer resins and transpolyisoprene resins are particularly suitable in terms of high elasticity and abrasion resistance. The ionomer resin has the general formula R-CH=
A copolymer of an α-olefin represented by CH ₂ (wherein R is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms) and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, Examples include ionic copolymers obtained by reacting with metal compounds. The α-olefins include ethylene, propylene, butene-1, pentene-1, and hexene-1.
1, heptene-1,3-methylbutene-1,4-
Examples include methylpentene-1. Further, α-olefins having a large number of carbon atoms can also be used in the present invention, but they are difficult to obtain and lack practicality. These α-olefins may be used alone or in combination of two or more. The content of α-olefins in the copolymer is preferably at least 50 mol%, and preferably more than 80 mol% in terms of processability and physical properties. Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, etc.; maleic acid, fumaric acid, etc., or monoesters of these dicarboxylic acids, such as maleic acid monomethyl ester. , fumaric acid monoethyl ester, and acid anhydrides of these dicarboxylic acids, such as maleic anhydride, but are not limited thereto. These α,β-unsaturated carboxylic acids may be used alone or in combination of two or more. α、β
- The content of unsaturated carboxylic acid in the copolymer is preferably 0.5 to 25 mol%, more preferably 1 to 10 mol%. In addition, as a component other than α-olefin and α,β-unsaturated carboxylic acid, monomers copolymerizable with these, such as styrene, vinyl chloride, vinyl acetate, acrylonitolyl, and vinyl methyl ether, may be used as a part of α-olefin. It is also possible to replace and copolymerize. The copolymer consisting of α-olefin and α,β-unsaturated carboxylic acid is not limited to one obtained by directly copolymerizing a mixture of monomers, but can be obtained from α-olefin. It may also be obtained by graft polymerizing an α,β-unsaturated carboxylic acid monomer onto a base polymer. An ionic copolymer is obtained by reacting (neutralizing) the thus obtained copolymer with a metal compound that generates metal ions. Metal ions suitable for producing the ionic copolymers include metal ions of group 1 or 2 of the periodic table, namely Na, K, Li, Cs, Cu, Ag and Be,
Mg, Ca, Sr, Ba, Zn, Cd, Hg are listed,
These may be used alone or in combination of two or more. Using these metal ions,
Cross-linking is preferably formed in the formation of the ionic copolymer. Among these metal ions,
Na and Zn are more preferred from the viewpoint of melt processability and physical properties in a solid state. The amount of ions used or the degree of neutralization of the copolymer cannot be determined unconditionally because it depends on the desired solid state properties and meltability of the ionic copolymer obtained. In order to significantly change the collective state of the polymer, the amount is preferably such that it neutralizes at least 10% of the carboxyl groups in the copolymer, and can usually neutralize up to about 90%. . The degree of neutralization to optimize the physical properties of an ionic copolymer varies depending on the use, and the physical properties of the ionic copolymer also vary depending on the carboxyl group concentration in the copolymer and the molecular weight of the copolymer. It is generally desirable to neutralize at least 50% of the carboxyl groups, although this cannot be determined unconditionally because of the differences in the carboxyl groups. The above-mentioned metal ions can be obtained by mixing metal compounds that generate such metal ions, such as inorganic compounds such as sodium hydroxide and potassium carbonate, or organic metal compounds such as sodium methoxide, sodium formate, and sodium acetate, with water. Alternatively, it can be obtained by dissolving it in an organic solvent such as methanol. There is no particular limitation on the method for obtaining the ionic copolymer from the copolymer and metal ions, and any known method may be used. The molecular weight of the ionic copolymer thus obtained is appropriately expressed by MI (melt index), which is a measure of melt viscosity described in ASTM D 1238. The range of MI of useful ionic copolymers is about 0.1 to 100 g/10 minutes (190°C), more preferably about 0.5 to 20 g/10 minutes (190°C). ionic copolymer
When the MI is about 0.1 to 100 g/10 minutes (190° C.), the material has excellent melt processability, is extremely strong in the solid state, and has appropriate elasticity and flexibility. In the present invention, these ionomer resins may be used in combination with commonly used fillers such as titanium oxide, talc, calcium carbonate, and silica. It is effective to utilize the technology related to JP-A-60-202142 using acid potassium fibers. In the present invention, the trans polyisoprene resin exists as a main component of naturally occurring balata and gutta percha, and has a molecular structure of trans-1,4-polyisoprene. Kuraray Trans Polyisoprene TP is a typical example of a commercially available product.
-301 [Clarei Soprene Chemical Co., Ltd.]. In the present invention, the fibrous alkali metal titanate has a fiber length of 1 μm to 1 mm and an aspect ratio of 5 to 1 mm.
It is preferable to have a fiber shape of 1000, particularly preferably an average fiber length of 5 to 300 μm, and an aspect ratio of 10 to 300 μm.
300, and those in this range have excellent reinforcing properties and homogeneous dispersibility, and can obtain a homogeneous strength distribution.
Specific examples include sodium titanate fiber, potassium titanate fiber, lithium titanate fiber, etc., which have excellent reinforcing properties, heat resistance, whiteness, can be colored to the desired color tone, and have fine and uniform fiber length. Potassium titanate fiber is a particularly suitable material because it can be easily produced and has high homogeneous dispersibility as a composite material. Potassium titanate fiber has the general formula _K2O・
It means a single crystal fiber represented by nTiO ₂ or the general formula K ₂ O・nTiO ₂・1/2H ₂ O (in both formulas, n represents an integer from 2 to 8), specifically, tetratitanic acid. Potassium fibers, potassium hexatitanate fibers, potassium octitanate fibers, etc. may be used alone, or two or more thereof may be used in combination. The average fiber diameter of these potassium titanate fibers is 0.1
-2 μm, average fiber length of 5-100 μm, and spectral ratio of 10-200. Here, the average fiber diameter and the average fiber length are the average values of the values measured for at least 10 or more fibers per field, examined using a scanning electron microscope in at least 5 or more fields of view, and the aspect ratio means the value obtained by dividing the average fiber length of such fibers by the average fiber diameter. In the present invention, examples of the surface treatment agent for treating the surface of the fibrous alkali metal titanate include sulfur-containing silane compounds such as mercapto group-containing silane compounds and silyl group-containing sulfide compounds. A typical example of the above mercapto group-containing silane compound is the general formula (R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 2 to 6 carbon atoms, R ² is a substituted or unsubstituted monovalent hydrocarbon group, X is a hydrolyzable group, a is a 1 to 3 carbon number integer,
b is an integer from 0 to 2, and 1≦(a+b)≦3. )
This is a compound represented by Examples of R ¹ include an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group, with an ethylene group and a trimethylene group being preferred, and a trimethylene group being particularly preferred. R ² is an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, octadecyl; alkenyl such as vinyl or allyl; phenyl group, aryl group such as tolyl group; aralkyl group such as benzyl group, β-phenylethyl group, β-phenylpropyl group; β-cyanoethyl group, γ-chloropropyl group, 3,3,
Substituted hydrocarbon groups such as 3-trifluoropropyl group and chlorophenyl group are exemplified, and various groups are selected depending on the type of rubber component and purpose of use. Aralkyl groups are added to rubber components containing aromatic rings,
Also, substituted hydrocarbon groups are effective for rubber components containing halogens, nitriles, and the like. X is a hydrolyzable group bonded to a silicon atom; an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group; Alkoxy group; Enoxy group such as isopropenyloxy group; Ketooximato group such as dimethylketoxima group, methylethylketooximato group; Amino group such as diethylamino group, dibutylamino group; Aminoxy group such as diethylaminoxy group; Acetoxy group, octa Examples include acyloxy groups such as a noyloxy group; and amide groups such as an N-methylacetamide group. Among these, lower alkoxy groups having 1 to 4 carbon atoms are preferred because they have excellent surface reactivity with fibrous alkali metal titanates, and among these, methoxy groups are particularly preferred because they have good reactivity. a is an integer of 1 to 3, preferably less than 2 on average, b is an integer of 0 to 2,
An average of 1 or less is preferable. If a and b are too large, the number of hydrolyzable groups will decrease and the reactivity with the fibrous alkali metal titanate will decrease, and if a is too small, the effect of the mercapto group on the rubber component will decrease. Preferably, the average value of a is adjusted to 1, and the average value of b is adjusted to less than 1. A typical example of a silyl group-containing sulfide compound is the general formula (R ³ is the same or different substituted or unsubstituted monovalent hydrocarbon group, R ⁴ is the same or different substituted or unsubstituted hydrocarbon group having 2 to 4 carbon atoms, Y is a hydrolyzable group , c is an integer of 0 to 2, and n is an integer of 1 to 6). R ³ is an alkyl group such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, octadecyl group; alkenyl group such as vinyl group or allyl group; phenyl group group, aryl group such as tolyl group; aralkyl group such as benzyl group, β-phenylethyl group, β-phenylpropyl group; β-cyanoethyl group, γ-chloropropyl group, 3,3,
Substituted hydrocarbon groups such as 3-trifluoropropyl group and chlorophenyl group are exemplified, and various groups are selected depending on the type of rubber component and purpose of use. Aralkyl groups are effective for components containing aromatic rings, and substituted hydrocarbon groups are effective for rubber components containing halogens, nitriles, etc. Examples of R ⁴ include an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group, with an ethylene group and a trimethylene group being preferred, and a trimethylene group being particularly preferred. Y is a hydrolyzable group bonded to a silicon atom, and includes alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy groups; Alkoxy group; Enoxy group such as isopropenyloxy group; Ketooxymato group such as dimethylketooximato group, methylethylketooximato group; Amino group such as diethylamino group, dibutylamino group; Aminoxy group such as diethylaminoxy group; Acetoxy group, octa Examples include acyloxy groups such as a noyloxy group; and amide groups such as an N-methylacetamide group. Among these, lower alkoxy groups having 1 to 4 carbon atoms are preferred because they have excellent surface reactivity with fibrous alkali metal titanates, and among these, propoxy groups are particularly preferred because they are easily synthesized and are stable compounds. c is an integer of 0 to 2, and one molecule of the silyl group-containing sulfide compound represented by the general formula () has at least one, preferably two, hydrolyzable groups that react with the surface of the fibrous alkali metal titanate. It is preferable that c is less than 2 on average. n is an integer from 1 to 6, with an average of 2 in view of ease of synthesis, affinity with rubber, and vulcanization inhibition.
-4 is preferred. In the present invention, the surface of the fibrous alkali metal titanate is treated with a surface treatment agent, and the amount of the surface treatment agent of the present invention used is generally about 0.05 to 10% by weight based on the fibrous alkali metal titanate. It is preferable to keep it in the range of . Within this range, the surface of the fibrous alkali metal titanate is sufficiently modified, and the physical properties of the rubber composition can be improved without inhibiting vulcanization during vulcanization, which will be described later. For the treatment method using the surface treatment agent of the present invention, any commonly used surface treatment method may be used. For example, the surface treatment agent of the present invention or its diluted solution is sprayed onto the fibrous alkali metal titanate surface. A method of homogeneous mixing with the fibrous alkali metal titanate or an impregnation treatment method can be adopted, and after the surface treatment agent of the present invention is uniformly adhered to the surface of the fibrous alkali metal titanate, the surface treatment agent is heated, dried, and hydrated. By performing decomposition or the like, the surface treatment agent of the present invention can be uniformly fixed to the surface of the fibrous alkali metal titanate. The surface treatment agent of the present invention contains a sulfur element in the molecule, and in particular, the terminal mercapto compound is a sulfur-containing compound that has been thought to inhibit vulcanization during peroxide-based vulcanization and deteriorate rubber physical properties. Although it is not clear by what mechanism of action the effect is expressed in the rubber composition, when fibrous alkali metal titanate is used, the effect is clearly expressed and the effect is achieved without inhibiting vulcanization. In addition to being homogeneously vulcanized, the fibrous alkali metal titanate and the rubber material are strongly bonded, and the sliding phenomenon at the interface between the fibrous filler and the rubber matrix, which is considered to be the cause of the decline in physical properties in composite materials, is eliminated. A rubber composition with high hardness and high compressive strength can be obtained. In the present invention, a golf ball with excellent impact resilience can be obtained by mixing the above-mentioned coating composition in a conventional kneading machine and then coating and molding it on the surface of a core material in an injection molding machine or the like. (Example) Examples and comparative examples will be described below. Examples 1 to 8 and Comparative Examples 1 to 8 Rubber (BR) (*1) 100 parts (by weight, the same applies hereinafter), zinc acrylate 10 parts, zinc oxide (*2) 15
10 parts of fumed silica (*3) and 15 parts of potassium titanate (untreated product) were put into a kneader and heated to 60~
After kneading for 10 minutes at 100°C, the contents were cooled to 60-70°C, 5 parts of dicumyl peroxide was added, the weight was adjusted, and the mixture was kneaded. A core material was obtained by wrapping an elastic thread (NR-based rubber thread) around the spherical core obtained by heating for 30 minutes. This core material was coated with a coating layer consisting of the ingredients shown in Tables 1 and 2 so that each ball weighed 45 g, and the core material was injection molded using an injection machine to obtain a thread-wound golf ball. The resulting balls were measured for their rebound resilience, durability, compression, and actual impact. The results are shown in Tables 1 and 2. In addition, in the above and table *1 Nippon Synthetic Rubber BR-11 *2 Seido Kagaku No. 3 Zinc White *3 Nippon Silica Nipseal VN3AQ Potassium titanate (untreated product) is Otsuka Chemical Co., Ltd.
Manufactured by Teismo D. Processed product A is Teismo D treated with 1% bis(3-triethoxysilylpropyl)tetrasulfide, and processed product B is Teismo D treated with 1% γ-mercaptopropyltrimethoxysilane. Processed product C is Teismo D treated with 1% γ-mercaptopropyltriethoxysilane, and Processed product D is Teismo D treated with 1% bis(3-trimethoxysilylpropyl)tetrasulfide. Treated product E is Teismo D treated with 1% γ-glycidoxypropyltrimethoxysilane. In addition, the durability index is expressed as an index by measuring the number of times until it breaks after applying compression that deforms it by 10 mm, and taking Example 1 as 100, and rebound resilience is based on JIS S7005.
It was dropped from a height of 120cm and the rebound height was measured at a measurement temperature of 20℃, and the compression showed the strength when compressed by 2.54mm. Examples 9 to 16 and Comparative Examples 9 to 16 A core material consisting of the formulations of Examples 1 to 8 excluding fumed silica was coated with a coating layer consisting of the formulations shown in Tables 3 and 4. Created a two-piece golf ball. The results are also shown in Tables 3 and 4. Examples 17 to 24 and Comparative Examples 17 to 24 Tables 5 and 6 were prepared using core materials and intermediate layers consisting of the formulations of Examples 9 to 16 plus 4 parts of anti-aging agent and 2 parts of stearic acid. A three-piece golf ball was prepared by coating it with a coating layer having the composition shown below. The results are also shown in Tables 5 and 6.

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Claims (1)

[Claims] 1. General formula (R ¹ is a substituted or unsubstituted divalent hydrocarbon group having 2 to 6 carbon atoms, R ² is a substituted or unsubstituted monovalent hydrocarbon group, X is a hydrolyzable group, a is a 1 to 3 carbon number integer,
b is an integer from 0 to 2, and 1≦(a+b)≦3. )
Mercapto group-containing silane compound and general formula represented by (R ³ is the same or different substituted or unsubstituted monovalent hydrocarbon group, R ⁴ is the same or different substituted or unsubstituted hydrocarbon group having 2 to 4 carbon atoms, Y is a hydrolyzable group , c is an integer of 0 to 2, and n is an integer of 1 to 6. A golf ball coating composition comprising one or a mixture of two or more natural rubbers. 2. The golf ball coating composition according to claim 1, wherein the synthetic rubber is an ionomer resin. 3. The golf ball coating composition according to claim 1, wherein the synthetic rubber is a transpolyisoprene resin.