JPH0626627B2 - Solid Golf Ball - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a one-piece golf ball capable of obtaining durability, impact resilience (flying characteristics), and excellent feeling on impact.

(Prior Art) A golf ball is required to have flight stability, long-distance flight performance, and the like, and those characteristics are required to have sufficiently controlled impact resilience, compressive strength, hardness, and the like. Various proposals have been made to improve the quality of the composition.

For example, it relates to a solid golf ball to which a metal salt monomer of α, β-monoethylenically unsaturated carboxylic acid added to a rubber composition is added, and these monomers are added to a rubber component by a free radical initiator. It is grafted to the polybutadiene main chain used as and acts as a co-crosslinking agent, which gives the ball hardness but durability.
No solid ball has been obtained that is satisfactory in terms of impact resilience. Further, the hardness of the golf ball can be adjusted by the amount of the cross-linking agent, but if the amount is increased, the impact resilience is lowered as a result.

Furthermore, various proposals have been made on fiber materials and fine particles for improving the hardness, durability, and high resilience of rubber compositions, but in all cases, the durability and resilience are reduced and modification cannot be expected so much at present. Atsuta Further, the fine fiber substance is uniformly dispersed in the rubber structure, but the wetting with the rubber substance is poor, and the surface treatment of the fiber surface has been a major problem. It was known that hydrolyzable silyl compounds were effective as these surface treatment techniques, but required a high degree of skill.

It has been found that sulfur-containing silane compounds are excellent surface-treating agents that are well compatible with rubber components, but these are all related to sulfur vulcanization systems. It was thought that the vulcanization mechanism was impractical for non-sulfur vulcanizing agents because of vulcanization inhibition.

(Problems to be Solved by the Invention) An object of the present invention is to provide a golf ball having excellent durability, impact resilience and hardness.

Another object of the present invention is to provide a golf ball reinforced with a fiber material surface-treated with a sulfur-containing compound that does not inhibit vulcanization even with a non-sulfur vulcanizing agent.

(Means for Solving Problems) The present invention was surface-treated with a surface treatment agent selected from mercapto group-containing silane compounds and silyl group-containing sulfaide compounds represented by the general formulas (I) and (II) described below. A solid golf ball is characterized by comprising one or a mixture of two or more kinds of fibrous alkali metal titanate and synthetic rubber and / or natural rubber.

As the rubber component of the present invention, various known rubbers can be used. For example, 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), fluorine rubber (FR), ethylene propylene rubber (EPR), chlorosulfonated polyethylene (C
SM), ethylene vinyl acetate rubber (EVA), chlorinated polyethylene (CPE), polyisobutylene (PIB), alphine rubber (AL), polyester rubber (ESR), shrimp chlorohydrin rubber (ECR), chlorinated butyl rubber (C)
IR), nitrile isobutylene rubber (NIR) and the like. Among these rubber components, it is particularly preferable to use a polybutadiene having a cis-1,4-structure of 30% by weight or more because the hardness and the impact resilience are improved. The reason for this is not clear, but the sulfur component of the surface treatment agent for fibrous alkali metal titanate is probably cis-1,4.
-It is considered that it reacts with the polybutadiene having a structure and exerts a reinforcing effect by effectively utilizing the fiber shape of alkali metal titanate, and a surface treatment agent containing no sulfur component, for example, methyltrimethoxysilane, methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Hardness and impact resilience are improved as compared with those using a commonly used alkoxysilane-based surface treatment agent such as aminopropylethoxysilane.

As the fibrous alkali metal titanate in the present invention,
A fiber having a fiber length of 1 μm to 1 mm and an aspect ratio of 5 to 1000 is suitable, and particularly preferably an average fiber length of 5 to 30.
It has a thickness of 0 μm and an aspect ratio of 10 to 300. Within this range, the reinforcing property and the homogeneous dispersibility are excellent, and a uniform strength distribution can be obtained. As a specific example, sodium titanate fiber,
Potassium titanate fibers, lithium titanate fibers, etc., which are excellent in reinforcing property, heat resistance, whiteness, can be toned in a desired color tone, and can easily produce fine and uniform fiber lengths, and are homogeneous as composite materials. Dispersible potassium titanate fibers are a particularly suitable material.

The potassium titanate fibers, the general formula K ₂ O · nTiO ₂ or the general formula _{K 2} O · nTiO 2 · 1
/ 2H _(in either the formula, n represents an integer of 2 to 8) 2 O refers to single crystal fibers represented by, specifically, 4 potassium titanate fiber, potassium hexatitanate fiber, potassium 8 titanate Examples thereof include fibers, and these may be used alone or in combination of two or more kinds. It is preferable that these potassium titanate fibers have an average fiber diameter of 0.1 to 2 μm, an average fiber length of 5 to 100 μm, and a spectral ratio of 10 to 200. Here, the average fiber diameter and the average fiber length are average values of values measured for at least 10 or more fibers per visual field by examining at least 5 or more visual fields using a scanning electron microscope. Means a value obtained by dividing the average fiber length of such fibers by the average fiber diameter.

In the present invention, examples of the surface treating 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 sulfaide compounds.

A typical example of the mercapto group-containing silane compound is a 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, and a is 1 to 3 An integer, b is an integer from 0 to 2,
1 ≦ (a + b) ≦ 3. ) 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, but an ethylene group and a trimethylene group are preferable, and a trimethylene group is particularly preferable.

R ² 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; vinyl group,
Alkenyl group such as allyl group; aryl group such as phenyl group and tolyl group; aralkyl group such as benzyl group, β-phenylethyl group, β-phenylpropyl group; β
-Substituted hydrocarbon groups such as cyanoethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl group, and chlorophenyl group are exemplified, and they are variously selected depending on the kind of rubber component and the purpose of use, and long-chain alkyl groups. The group is effective for a rubber component containing no aromatic ring, the aryl group and the aralkyl group are effective for a rubber component containing an aromatic ring, and the substituted hydrocarbon group is effective for a rubber component containing halogen, nitrile and the like.

X is a hydrolyzable group bonded to a silicon atom and is an alkoxyl group such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group; an alkoxy group such as a β-methoxyethoxy group, a β-ethoxyethoxy group and a β-butoxyethoxy group. Alkoxy group; enoxy group such as isopropenyloxy group; ketooxymato group such as dimethylketooxymato group and methylethylketooxymato group; amino group such as diethylamino group, dibutylamino group; aminoxy group such as diethylaminoxy group; acetoxy group, octa Examples thereof include an acyloxy group such as a noyloxy group and an amide group such as an N-methylacetamide group. Among these, a lower alkoxy group having 1 to 4 carbon atoms is preferable because of its excellent surface reactivity with fibrous alkali metal titanate, and among them, a methoxy group having particularly good reactivity is preferable. a is an integer of 1 to 3, preferably less than 2 on average, and b is an integer of 0 to 2 on average 1
The following are preferred. If a and b are too large, the number of hydrolyzable groups decreases and the reactivity with fibrous alkali metal titanate decreases, and if a is too small, the effect of the mercapto group on the rubber component decreases. It is preferable that the average value of a is adjusted to 1 and the average value of b is adjusted to less than 1.

Typical examples of the silyl group-containing sulfaide compound include those represented by the general formula: (R ³ is the same or different from each other, a substituted or unsubstituted monovalent hydrocarbon group, R ⁴ is the same or different from each other, a substituted or unsubstituted hydrocarbon group having 2 to 4 carbon atoms, and 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; vinyl group,
Alkenyl group such as allyl group; aryl group such as phenyl group and tolyl group; aralkyl group such as benzyl group, β-phenylethyl group, β-phenylpropyl group; β
-Substituted hydrocarbon groups such as cyanoethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl group, and chlorophenyl group are exemplified, and they are variously selected depending on the kind of rubber component and the purpose of use, and long-chain alkyl groups. The group is effective for a rubber component containing no aromatic ring, the aryl group and the aralkyl group are effective for a rubber component containing an aromatic ring, and the substituted hydrocarbon group is effective for a rubber component containing halogen, nitrile and the like.

Examples of R ⁴ include an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group, but an ethylene group and a trimethylene group are preferable, and a trimethylene group is particularly preferable.

Y is a hydrolyzable group bonded to a silicon atom and is an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group; an alkoxy group such as a β-methoxyethoxy group, a β-ethoxyethoxy group and a β-butoxyethoxy group. Alkoxy group; enoxy group such as isopropenyloxy group; ketooxymato group such as dimethylketooxymato group and methylethylketooxymato group; amino group such as diethylamino group, dibutylamino group; aminoxy group such as diethylaminoxy group; acetoxy group, octa Examples thereof include an acyloxy group such as a noyloxy group and an amide group such as an N-methylacetamide group. Of these, lower alkoxy groups having 1 to 4 carbon atoms are preferable because they have excellent surface reactivity with fibrous alkali metal titanate, and among them, a propoxy group, which is a compound that is easy to synthesize and stable, is particularly preferable.

c is an integer of 0 to 2 and at least one hydrolyzable group that reacts with the surface of the fibrous alkali metal titanate in one molecule of the silyl group-containing sulfaido compound represented by the general formula (II), preferably It is desirable to include two, c
Is preferably less than 2 on average. n is an integer of 1 to 6, and is preferably 2 to 4 on average in view of easiness of synthesis, affinity with rubber and inhibition of vulcanization.

In the present invention, the surface of the fibrous alkali metal titanate is treated with the surface treating agent, and the amount of the surface treating agent of the present invention is generally about 0.05 to about 5 to the fibrous alkali metal titanate.
It is preferably in the range of 10% by weight. In 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 causing vulcanization inhibition during vulcanization described later.

The treatment method with the surface treatment agent of the present invention may be any of the commonly used surface treatment methods. For example, the surface treatment agent of the present invention or a diluent thereof is sprayed onto the surface of a fibrous alkali metal titanate. A treatment method, a method of homogeneously mixing or impregnating with a fibrous alkali metal titanate can be adopted, and after uniformly adhering the surface treatment agent of the present invention to the surface of the fibrous alkali metal titanate, it is dried by heating and hydrolyzed. By performing decomposition or the like, the surface treatment agent of the present invention can be fixed uniformly on the surface of the fibrous alkali metal titanate.

The surface treatment agent of the present invention contains elemental sulfur in the molecule,
In particular, the terminal mercapto compound is a sulfur-containing compound that has been said to cause vulcanization inhibition during peroxide vulcanization and deteriorate rubber properties. What kind of action mechanism does the rubber composition exhibit in the rubber composition? Although it is not clear, when fibrous alkali metal titanate is used, the effect is remarkably exhibited, and the fibrous alkali metal titanate and the rubber substance are uniformly vulcanized without causing vulcanization inhibition. Are firmly bonded to each other, the slip phenomenon at the interface between the fibrous filler and the rubber matrix, which is considered to be the cause of the deterioration of the physical properties of the composite material, is suppressed, and a rubber composition having high hardness and high compression strength is obtained.

In the present invention, an unsaturated carboxylic acid, a salt thereof, other unsaturated vinyl compound or the like can be used as the crosslinkable monomer. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, 2-acetaminoacrylic acid,
β, β-dimethacrylic acid, ethacrylic acid, α-chloroacrylic acid, cinnamic acid, acotinic acid, 2-ethyl-3-propylacrylic acid, crotonic acid, aminocrotonic acid, acidphoshydroxyethyl (meth) acrylate, β -Acryloxypropionic acid, 2-butene-1,4-dicarboxylic acid, sorbic acid, acetylcarboxylic acid, N-butylmaleamic acid, fumaric acid, maleic acid, chloromaleic acid, di-n-butylmaleic acid, N , N-dimethylmaleic acid, N-ethylmaleate acid, N-phenylmaleamic acid, dichloromaleic acid, dihydroxymaleic acid, allylarsonic acid, chloroendeic acid, itaconic acid, benzoylacrylic acid, etc. Other unsaturated vinyl compounds include, for example, vinyl acetate, vinyl propionate, caps Nsan vinyl, styrene, vinyl toluene, vinyl compounds such as divinylbenzene, acrylic acid, alkyl esters of methacrylic acid; (meth)
(Meth) acrylic acid derivatives such as acrylonitrile, (meth) acrylamide, and glydyl (meth) acrylate;
Various compounds such as triallyl isocyanurate can be exemplified. Of these, acrylic acid, methacrylic acid, cinnamic acid, acotinic acid, crotonic acid, itaconic acid and benzoylacrylic acid are preferred. These compounds can be used alone or as a mixture of two or more kinds. In the present invention, a metal salt of the above-mentioned unsaturated carboxylic acid can also be used, and typical examples of the metal are lithium, sodium, potassium, strontium, zinc, magnesium, calcium, barium, cadmium, lead, silconium, beryllium,
Copper, aluminum, tin, iron, antimony, bismuth,
Any one kind or a mixture of two or more kinds of molybdenum, tungsten, nickel, etc. can be used, and a divalent or higher valent metal salt is preferable from the viewpoint of increasing the crosslinking effect, and calcium, zinc from the viewpoint of easy availability and low toxicity. , Magnesium, zirconium and the like are preferable. Incidentally, these metal species are used as a metal salt of an unsaturated carboxylic acid previously reacted with a unsaturated carboxylic acid, as well as an unsaturated carboxylic acid and these metals, metal oxides, hydroxides, carbonates. A metal salt may be prepared by separately mixing a salt and the like into the rubber component and reacting them in a mixed system. The amount of the crosslinkable monomer used in the present invention is not particularly limited, 0.1 to 50 parts by weight with respect to 100 parts by weight of the rubber component,
The amount is preferably 1 to 15 parts by weight, more preferably 3 to 9 parts by weight. Within this range, the durability is excellent and the hardness of impact resilience can be easily adjusted.

Examples of the non-sulfur-based vulcanizing agent of the present invention include metal oxides such as magnesium oxide, lead oxide and zinc oxide; crosslinkable resins such as phenol resin, melamine formaldehyde resin, urethane resin, polyester resin, polyamide resin and epoxy resin; These low molecular weight compounds or modified products; diacetyl peroxide, dibenzoyl peroxide,
Dicapryl peroxide, di (p-chlorobenzoyl) peroxide, didecanoyl peroxide, di (2,4-dichlorobenzoyl) peroxide, diisobutyl peroxide, diisononanoyl peroxide, dilauroyl peroxide, dipera Gonyl peroxide, dipropynyl peroxide, di (β-carboxypropinoyl) peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dihydroxy-dimethyl-dioxacyclopentane, t-butyl peroxide, t-butyrupperoxy (2- Ethylhexanoate), t-butylperoxyisobutyrate, O, Ot-butyl-O-isopropylmonoperoxycarbonate, t-butylperoxypivalate, dimethyl- (Benzoylperoxy) hexane, t-butylperoxy (2-ethylbutyrate), di-t-butylperoxide, dicumyl peroxide, dimethyl-bis (t-butylperoxy) hexane, t-butylhydroper Oxide, walnut hydroperoxide, bis (t-butylperoxy)
Examples thereof include organic peroxides such as trimethylcyclohexane and n-butylbis (t-butylperoxy) valerate. Among these, dicumyl peroxide, cumyl hydroperoxide, t-butyl peroxide, dibutyl peroxide, bis (t-butylperoxy) trimethylcyclohexane, n-butylbis (t
-Butylperoxy) parylate and the like are suitable in that the vulcanization proceeds uniformly due to the relationship between the vulcanization temperature and the half-life. These non-sulfur-based vulcanizing agents can be used alone or as a mixture of two or more, and the amount used is the type of rubber used,
It is optionally selected depending on the purpose of use of the rubber composition, etc., but normally it is preferably used in the range of about 0.1 to 15% by weight based on the rubber component.

In the present invention, it is possible to add various known additives,
For example, vulcanization accelerator, vulcanization retarder, antioxidant, plasticizer,
A peptizing agent, a tackifier, an anti-tacking agent, a foaming agent, a dispersant, a dusting agent, a release agent, a solvent, a softening agent and the like can be added if necessary. Further, in the present invention, as a reinforcing material, clay such as carbon black, magnesium carbonate, zinc oxide, calcium carbonate, barium sulfate, aluminum hydroxide, aluminum oxide, silica powder, titanium oxide, mica, talc, clay, diatomaceous earth, kaolin, etc. Various inorganic fillers such as powders and optional pigments and dyes as colorants can also be used in combination. Further, any resin commonly used as an organic modifier, for example, coumarone indene resin, phenol resin, polyethylene resin, acrylic resin, polyamide resin, epoxy resin, urethane resin, polyolefin resin, etc., may be mixed and used. . Furthermore, in the present invention, long-fiber reinforcing agents usually used, for example, inorganic fibers such as glass fiber, carbon fiber, metal fiber, quartz fiber, ceramic fiber; nylon fiber, vinylon fiber, polyester fiber, aromatic polyamide fiber, polyimide fiber, Organic fibers such as aromatic polyetheramide fibers can also be used in combination.

The golf ball of the present invention has a fibrous alkali metal titanate treated with the above-mentioned surface treatment agent, a rubber component, a vulcanizing agent, various additives optionally added, and an auxiliary agent after kneading by a usual method about 80 It is obtained by molding a golf ball that has been vulcanized at ~ 180 ° C for about 5 to 60 minutes, and the composition ratio of each component cannot be specified because it is adjusted depending on the type of rubber component and purpose of use, but the surface-treated fiber The amount of the alkali metal titanate compounded is usually about 2 to 100 parts with respect to 100 parts by weight of the rubber component, particularly preferably about 10 to 50 parts, and if it is too small, it is soft but it is difficult to develop strength. If it is too large, the strength will increase, but it will be too hard, and the elongation will be insufficient, making it less practical. In the present invention, the surface treatment may be carried out with a coating agent which is usually used. In the present invention, the rubber or the crosslinkable monomer reacts with the vulcanizing agent, and the surface-treated fibrous alkali metal titanate reacts via the mercapto group.

(Effects of the Invention) The one-piece golf ball of the present invention exerts rubber properties that are not present in conventional golf balls, has high strength, high resilience, and good feeling upon hitting, resulting in an excellent flight distance. be able to.

(Example) Below, an example and a comparative example are given and demonstrated. Example 1
18 and Comparative Examples 1 to 7 All kinds and all amounts of each component other than the vulcanizing agent were put into a kneader, and the contents were 60 to 70 after kneading at 60 to 100 ° C for 10 minutes. After cooling to ℃, add vulcanizing agent,
After adjusting the weight to 45 g and kneading it, vulcanize it with an ordinary golf ball mold at 150 ± 5 ° C for 30 minutes to make a golf ball, and then its rebound resilience, durability, compression, and actual impact. I took a measurement. The results are shown in Table 1.

Examples 21 to 27 and Comparative Examples 21 to 27 Experiments were performed in the same manner as in Example 1 except that the components shown in Table 2 were used. The results are shown in Table 2.

Examples 31 to 37 and Comparative Examples 31 to 32 Experiments were performed in the same manner as in Example 1 except that the components shown in Table 3 were used. The results are shown in Table 3.

Examples 41 to 50 and Comparative Examples 41 to 44 Experiments were conducted in the same manner as in Example 1 except that the components shown in Table 4 were used. The results are shown in Table 4.

In the table, * 1 Japan Synthetic Rubber BR-11 * 2 Japan Synthetic Rubber STEREON 720 * 3 Japan Synthetic Rubber IR-2200 * 4 Shodo Kagaku No. 3 Zinc Flower * 5 Nippon Silica Nipseal VN3AQ Potassium titanate (untreated product) Is manufactured by Otsuka Chemical Co., Ltd., Tesmo D. Treated product A is treated with Teismo D using 1% of bis (3-triethoxysilylpropyl) tetrasulfaid. Treated product B is Teismo D γ-mercaptopropyl. Treated product C was treated with 1% trimethoxysilane, Treated product C was treated with Teismo D using 1% γ-mercaptopropyltriethoxysilane, and treated product D was Teismo D with bis (3-trimethoxysilylpropyl). ) Treated with tetrasulfaid 1%, treated product E is Teismo D γ-glycidoxypropyltrimetho It is obtained by treatment with 1% Shishiran.

Incidentally, the durability index is expressed as an index with the number of times up to fracture measured by applying compression that deforms by 10 mm and setting Example 1 as 100, and the impact resilience is dropped from a height of 120 cm according to JIS S7005, The height of repulsion was measured at a measurement temperature of 20 ° C., and the complex showed a strength at 2.54 mm compression.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Wada 463, Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd., Tokushima Laboratory (72) Masayoshi Suzue 463, Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Tokushima Laboratory, Tsuka Chemical Co., Ltd. (72) Inventor Takuro Morimoto 5-16 Yosai, Momoyama-cho, Fushimi-ku, Kyoto-shi, Kyoto Prefecture

Claims (5)

[Claims] 1. A 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, and a is 1 to 3 An integer, b is an integer from 0 to 2,
1 ≦ (a + b) ≦ 3. ) A mercapto group-containing silane compound represented by (R ³ is the same or different from each other, a substituted or unsubstituted monovalent hydrocarbon group, R ⁴ is the same or different from each other, a substituted or unsubstituted hydrocarbon group having 2 to 4 carbon atoms, and Y is a hydrolyzable group. , C is an integer of 0 to 2, and n is an integer of 1 to 6.) A fibrous alkali metal titanate surface-treated with a surface treatment agent selected from a silyl group-containing sulfaide compound represented by / Or a mixture of one or more kinds of natural rubber, a solid golf ball. 2. Synthetic rubber and / or natural rubber is cis-1,
The solid golf ball according to claim 1, which contains 30% by weight or more of 4-structured polybutadiene. 3. (a) 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, and a is 1 to 3 An integer, b is an integer from 0 to 2,
1 ≦ (a + b) ≦ 3. ) A mercapto group-containing silane compound represented by (R ³ is the same or different from each other, a substituted or unsubstituted monovalent hydrocarbon group, R ⁴ is the same or different from each other, a substituted or unsubstituted hydrocarbon group having 2 to 4 carbon atoms, and Y is a hydrolyzable group. , C is an integer of 0 to 2, and n is an integer of 1 to 6). A fibrous alkali metal titanate surface-treated with a surface treatment agent selected from the silyl group-containing sulfaido compounds represented by the formula (b). One or more types of synthetic rubber and / or natural rubber, and (c) a mixture of crosslinkable monomers (a), (b) and (c) are vulcanized with a non-sulfur vulcanizing agent. A solid golf ball. 4. Synthetic rubber and / or natural rubber is cis-1,
A solid golf ball according to claim 3, which comprises 30% by weight or more of 4-structured polybutadiene. 5. The cross-linkable monomer is an unsaturated carboxylic acid, a salt thereof or an unsaturated vinyl compound, as claimed in claim 3.
A solid golf ball according to the item.