JPH08131580A - Solid golf ball - Google Patents

Abstract

PURPOSE: To provide a two-piece solid golf ball by which responsiveness like a rubber thread type golf ball and ball hitting feeling can be obtained, and which is excellent in durability (impact resistance) and bounce. CONSTITUTION: In a solid golf ball formed of a composite structure wherein a rubber elastic material is taken as a core material, and a hard elastic body is applied on the outer peripheral surface, a compression value in 10mm deforming of a golf ball is 700kgf to 900kgf. It is desirable that the compression value of the core material in 10mm deforming is within the range of 600kgf to 800kgf, and a coated layer coated on the outer peripheral surface of the core material is made of ionomer resin, and it is desirable that the resin has the tensile elongation of 400% or more and that 50% modulus is 1.5kgf/mm<2> or more. Moreover, the surface hardness of the solid golf ball is less than 70 by an ASTM-D hardness meter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid golf ball, and more particularly to a solid golf ball having a good feel on impact and excellent durability (impact resistance) and resilience.

[0002]

2. Description of the Related Art There are thread wound golf balls and two-piece golf balls generally used in golf competitions. Among these, a two-piece golf ball is constructed by covering a core made of a rubber composition with a cover made of an ionic ethylene copolymer resin having excellent impact resistance and resilience.

The two-piece golf ball thus obtained has a long flight distance and excellent durability, and is used by many golfers. However, golfers who prefer a soft shot feeling tend to prefer a wound golf ball because of a hard feel at the time of hitting. Therefore, it has been desired to develop a two-piece golf ball having an appropriate shot feeling.

[0004]

When a softer core material is used to soften the above two-piece golf ball, the feel on impact is considerably improved (Japanese Patent Laid-Open No. 61-115581). , Tokuhei 2-161
52, Japanese Patent Publication No. 2-24150, Japanese Patent Publication 6-
No. 4105), the deformation at the time of hitting is large, so that there is much loss in resilience, it is difficult to greatly improve resilience performance, and it is also disadvantageous in durability.

In order to achieve the above-mentioned object, the present invention provides a two-piece solid golf ball which has a feeling similar to a wound golf ball and a soft shot feeling, and is excellent in durability (impact resistance) and resilience. To aim.

[0006]

SUMMARY OF THE INVENTION The present invention is a solid golf ball having a composite structure in which a rubber-like elastic body is used as a core material and a hard elastic body is coated on the outer peripheral surface of the core to form a coating layer. The gist is that the compression value when deformed by 10 mm is 700 kgf to 900 kgf.

The core material preferably has a compression value within a range of 600 kgf to 800 kgf when deformed by 10 mm, and the coating layer coating the outer peripheral surface of the core material is made of an ionomer resin. Has a tensile elongation of 400% or more and a 50% modulus of 1.5 kgf / mm
It is preferably ² or more. The surface height of the solid golf ball is less than 70 according to the ASTM-D hardness tester.

The present invention is configured as described above, and the configuration of the present invention will be specifically described below. (1). Core material (core material) The core material is usually composed of a base rubber, a crosslinking agent, a reinforcing agent, and a vulcanizing agent. The main component of the base rubber is polybutadiene,
As the cross-linking agent, α, β-ethylenically unsaturated carboxylic acid such as (meth) acrylic acid or a salt thereof, bismaleimide compound, urethane (meth) acrylate is used.

As the reinforcing agent, silicon dioxide, metal oxide or the like is used. Alkyl peroxide is usually used as the vulcanizing agent. Although the composition of the core material used in the present invention is not limited, the compression value when deformed by 10 mm is in the range of 600 kgf to 800 kgf. If the compression value exceeds 800 kgf, a soft shot feeling cannot be obtained.

If it is less than 600 kgf, it is too soft and feels unreliable when hitting a ball. The increase or decrease of the compression value can be adjusted by the amount of the crosslinking agent. here,
The compression value is 10 at a compression speed of 10 mm / min.
mm The force required to deform (kgf). Further, it is desirable to specifically use the following materials as the composition constituting the core material used in the present invention.

(A). Base Rubber The base rubber used in the present invention is a rubber containing polybutadiene having a cis-1,4-structure of at least 40%, preferably 90% or more. Cis-1,4-structure is 4
If it is less than 0%, the resilience is lowered and therefore it is unsuitable for use in the solid golf ball which is the object of the present invention.

The above-mentioned polybutadiene rubber is preferably used alone as the base rubber, but if necessary, a normal polybutadiene rubber or a rubber component conventionally used as a base rubber for solid golf balls, such as natural rubber, is used. Rubber, isoprene rubber, styrene-butadiene rubber and the like can be compounded. (b). α, β-ethylenically unsaturated carboxylic acid or its gold
Group salt The α, β-ethylenically unsaturated carboxylic acid or metal salt thereof used herein is, for example, acrylic acid or methacrylic acid. Examples of the metal salt include zinc acrylate and zinc methacrylate. Most preferred here is zinc acrylate, a compound having the formula:

[0013]

Embedded image Examples of the zinc acrylate include zinc diacrylate sold under the trade name of RT manufactured by Sartoma Company in the United States. This product contains about 10% zinc palmitate and zinc stearate to improve dispersibility.

(C). Urethane Acrylate Urethane acrylate is a (meth) acrylate group-containing urethane compound obtained by reacting an isocyanate or an isocyanate prepolymer with a di- or poly (meth) acrylate having a hydroxyl group. In this case, the isocyanate prepolymer is a polyol such as glycol, triol or tetrol, or has a molecular weight of 2
000 or less polyether diol, polyether triol, polycaprolactone ester diol, and a prepolymer having an isocyanate group at the end obtained by reacting polycaprolactone triol with di- or triisocyanate.

The di- or poly (meth) acrylate having a hydroxyl group is obtained by reacting acrylic acid or methacrylic acid or a derivative thereof with a polyhydric alcohol, or acrylic acid or methacrylic acid or a derivative thereof and an epoxy group. And the like, which are obtained by reaction with a compound possessed by the compound. The above-mentioned di- or poly (meth) acrylate having a hydroxyl group easily reacts with isocyanates to form urethane acrylate.

Further, a urethane acrylate obtained by reacting a glycol or a polyol with a diisocyanate to form an adduct having an isocyanate group, and reacting this with the above-mentioned di- or poly (meth) acrylate having a hydroxyl group is used in the present invention. Can be used as the urethane acrylate in. Furthermore, molecular weight 2
A urethane acrylate obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting a polyol of 000 or less with a diisocyanate with the above-mentioned di- or poly (meth) acrylate having a hydroxyl group can also be used as the urethane acrylate in the present invention. .

The molecular weight of 2000 or less is not preferable because the cross-linking density becomes low when the molecular weight exceeds 2000, and the desired hardness of the present invention cannot be expected. (d). Metal oxide, for example, zinc oxide. A commercially available product may be used. It is mainly used for adjusting the weight of golf balls.

(E). Alkyl peroxide Generally commercially available products such as dicumyl peroxide may be used. Alkyl peroxide is used as a polymerization initiator. (f). Silicon dioxide The silicon dioxide used here has a specific surface area of 160 to 340 m ² / g according to the BET method and a purity of 99% or more. These include AEROSIL 200 (trade name), AEROSIL 200V (trade name), AEROSIL 300 (trade name), REOLOSIL QS-102 (trade name) and the like.

(G). Bismaleimide Compound Examples of the bismaleimide compound include N, N′-ethylene bismaleimide, N, N′-trimethylene bismaleimide,
N, N'-m-phenylene bismaleimide, N, N'-4,
4'-diphenylmethane bismaleimide, N, N'-4,
4'-diphenyl ether bismaleimide, N, N'-4,
4'-diphenyl sulfone bismaleimide and the like can be mentioned.

In the present invention, the base rubber, zinc acrylate, metal oxide, and alkyl peroxide are blended and used as the core of the golf ball. Also, if necessary,
Urethane acrylate, silicon dioxide, and bismaleimide compound may be added appropriately. The amount of zinc acrylate compounded is 5 to 50 parts by weight based on 100 parts by weight of the base rubber. 5
If the amount is less than 50 parts by weight, no effect is obtained, and if the amount exceeds 50 parts by weight, the obtained core becomes too hard.

The amount of the metal oxide compounded is 5 to 50 parts by weight. The weight of the golf ball may be adjusted within this range so as to have a specified weight. Silicon dioxide may be added if necessary, but the compounding amount is 10 to 30 parts by weight.
If it is less than 10 parts by weight, the breaking strength of the resulting golf ball will be poor, and if it exceeds 30 parts by weight, the durability will be improved but the impact resilience will be lowered.

Urethane acrylate may be added if necessary, but the compounding amount thereof is 30 parts by weight or less. Three
If it exceeds 0, the compression will be too high and the hardness will be too high. The bismaleimide compound may be added if necessary, but the compounding amount thereof is 20 parts by weight or less. This is because if it exceeds 20 parts by weight, the compression becomes high and it becomes too hard.

In order to form a core from the rubber composition obtained as described above, this composition may be uniformly kneaded by a usual method and then heat-vulcanized under pressure to integrally mold it.
Vulcanization is generally performed by peroxide vulcanization with an organic peroxide such as peroxide. (2). Cover Material Although the composition of the cover material used in the present invention is not limited, the tensile elongation is 400% or more, preferably 400% to 600%, and the 50% modulus is 1.5 kgf / m.
m ² or more, preferably 1.5 kgf / mm ^{2 to} 3.0 kgf / mm
² An ionic ethylene copolymer is used.
If the tensile elongation is less than 400%, the required impact resistance cannot be obtained. Even if the tensile elongation is 400% or more, 5
When the 0% modulus is less than 1.5 kgf / mm ² , the impact resistance is excellent, but the resilience is poor. As the composition constituting the cover material used in the present invention, specifically, the following materials are preferably used.

(A). Ionic ethylene copolymer Obtained from an ethylene-unsaturated carboxylic acid copolymer and a metal compound capable of supplying a cation, or an organic amine.
The manufacturing method is not particularly limited, and a known method is used. These are, for example, Mimi DuPont Polychemical Co., Ltd., Himilan, HPR, Du Pont, Surlyn, and Exxon Chomi.
For example, IOTEC manufactured by cal. These ionic ethylene copolymers may be used alone or as a mixture of several kinds. .Ethylene-unsaturated carboxylic acid copolymer, for example, ethylene and an unsaturated carboxylic acid having 3 to 6 carbon atoms,
For example, it is a copolymer with acrylic acid, methacrylic acid, maleic acid, fumaric acid, vinyl benzoate or the like. . Metal compound capable of supplying cation Alkali metal, alkaline earth metal, formate such as transition metal, acetate, nitrate, carbonate, hydrogen carbonate, oxide,
Hydroxides, alkoxides and the like. The types of metals include Na, Zn, Li, Mg, Mn, Ca, Co and K. .Amines are aromatic or alicyclic compounds having a bisaminoalkyl group. For example, m-xylene diamine, o-xylene diamine, p-xylene diamine, or hydrogenated products of these, 1,3-bisaminomethylcyclohexane,
1,2-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane and the like are used.

(B). White Pigment As the white pigment, titanium oxide, zinc oxide, calcium carbonate, lead white, zinc sulfide, barium sulfate, gypsum, precipitated silica or the like is used. Titanium oxide is preferable. Upon blending, it is advisable to carry out melt-kneading at a temperature of 100 to 250 degrees. In addition, if necessary, an antioxidant, a stabilizer, a lubricant,
Additives such as colorants may be added as appropriate.

Specifically, high milan 1605, a blend of high milan 1605 and high milan 1855, a blend of high milan 1605 and high milan 1705, and the like are preferable.

[0027]

EXAMPLES The effects of the present invention will be specifically described below with reference to Examples and Comparative Examples. [Examples, Conventional Examples, Comparative Examples] Rubber compositions were prepared according to a conventional method by the compounding recipe (parts by weight) shown in Table 1 below. Each of the obtained rubber compositions was press-molded at 160 ° C. for 20 minutes to obtain spherical solid cores having a diameter of 38.3 mm.

The cover material composition having the formulation (parts by weight) shown in Table 2 was obtained by melt-kneading at a temperature of 200 ° C. using a twin-screw extruder. As a sample for measuring the characteristics of the cover material, the obtained cover material was press-molded at 170 degrees to obtain a sheet. The golf ball for characteristic measurement is
The above core material was adjusted by coating it by injection molding so that the cover material had a thickness of 2.3 mm. The properties of the adjusted core material, cover material and golf ball are shown in Table 3.

[0029]

[Table 1] 1) BR-01 made by Nippon Synthetic Rubber Co., Ltd .: cis 1,4 structure 97
% 2) Reaction product of hexamethylene diisocyanate and glycerin dimethacrylate: number of functional groups 4 3) Mitsui Toatsu Co., Ltd. N, N'-4,4'-diphenylmethane bismaleimide 4) Nippon Aerosil Co., Ltd. AEROSIL 200 5) Dicumyl peroxide

[0030]

[Table 2] 6) Mitsui DuPont Polychemical Co., Ltd. sodium ionic ethylene copolymer 7) Mitsui DuPont Polychemical Co., Ltd. zinc ionic ethylene copolymer 8) Mitsui DuPont Polychemical Co., Ltd. zinc ionic ethylene Copolymer 9) Sodium ionic ethylene copolymer manufactured by Mitsui DuPont Polychemical Co., Ltd. 10) Zinc ionic ethylene copolymer manufactured by Mitsui DuPont Polychemical Co., Ltd. 11) Taipaque CR manufactured by Ishihara Sangyo Co., Ltd. -60-2: Average particle size 0.
21 μm

[0031]

[Table 3] 12) Force required to deform a golf ball or core material by 10 mm at a compression speed of 10 mm / min (kgf) 13) Elongation at break during tensile test (%) Sample shape: JIS No. 2 for plastics Tensile speed: 100 mm / min test Condition: According to JIS K7113 14) Stress value at 50% deformation (kgf / mm ² ) in the above measurement 15) Crack when hit with a driver (Wood club No. 1) at a head speed of 43 m / sec using a swing robot Number of hits until occurrence, expressed as an index with Comparative Example 1 as 100 16) The initial velocity ratio of the golf ball to the head speed when hit with a driver (Wood Club No. 1) at a head speed of 43 m / sec using a swing robot The surface hardness of a golf ball measured using an ASTM-D (2240) hardness tester 18) The feel of a golf club No. 1 hit by a professional golfer 19) Feeling of Putting by Professional Golfer As is clear from Table 3, in Examples 1 to 7, Conventional Example 1 to
It can be seen that, as compared with No. 2, it has a soft or moderate feel at impact.

When a cover material having a tensile elongation of less than 400% is coated as in Comparative Examples 1 and 3 to 6, the surface hardness is high and the feeling during putting becomes hard, so a considerably hard core material is used. Failure to do so will result in poor durability. On the other hand, as in Comparative Example 2, even when the tensile elongation exceeds 400%, when a cover material having a modulus value of less than 1.5 kgf / mm ² is coated, the durability is excellent, but the rebound is high. The result is inferior. Moreover, the driver feels too soft and unreliable.

That is, in order to obtain a two-piece solid golf ball which has a soft or appropriate shot feeling when hit with a driver as in the present invention (at the time of large deformation) and at the time of putting (at the time of small deformation), as described above. It is necessary to use a core having a large compression area and to coat a cover material having high elongation and high modulus.

[0034]

As described above, the present invention is a solid golf ball having a composite structure in which a rubber-like elastic material is used as a core material and a hard elastic material is coated on the outer peripheral surface to form a coating layer. Since the compression value when deformed by 10 mm is 700 kgf to 900 kgf, the golf ball of the present invention has excellent durability (impact resistance), impact resilience, and large deformation (when hit with a driver), It has the effect of having an appropriate feel at impact during both small deformation (putting).

Claims (4)

[Claims] 1. A solid golf ball having a composite structure in which a rubber-like elastic material is used as a core material, and a hard elastic material is applied to the outer peripheral surface of the core material to form a coating layer.
The compression value when deformed is from 700kgf to 900
Solid golf ball characterized by being kgf. 2. The solid golf ball of claim 1, wherein the core material has a compression value when deformed by 10 mm within a range of 600 kgf to 800 kgf. 3. The coating layer coating the outer peripheral surface of the core material,
The solid golf ball according to claim 1, which is composed of an ionomer resin and has a tensile elongation of 400% or more and a 50% modulus of 1.5 kgf / mm ² or more. 4. The surface height of the golf ball is ASTM
A solid golf ball having a D hardness meter of less than 70.