JPH11333026A - Three-piece solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject ball giving a good hitting feeling as well as flying performace when hitted by a driver and excellent in a control characteristic and hitting feeling when hitted by an iron. SOLUTION: This ball comprises a core 1, an intermediate layer 2 and a cover 3 covering the layer 2. The surface hardness of the cover 3 is 65-35 of JIS-C hardness. An amount of deformation in the core 1 from the state that the core is loaded with an initial load of 10 kgf to the state that it is loaded with a final load of 130 kgf is 2.8-5.3 mn. The hardness of the core from its center to the surface is substantially even. The layer 2 has the Shore hardness of 63-70. The cover 3 has the Shore hardness of 45-62. The difference in hardness between the layer 2 and the cover 3 is 3-20 in Shore hardness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-piece solid golf ball, and more particularly, to a three-piece solid golf ball having good flight performance with a driver and good feeling at impact, and excellent controllability at iron shot and excellent feeling at impact. About the ball.

[0002]

2. Description of the Related Art At present, there are golf balls of various structures on the market, and there are generally two-piece solid golf balls and thread wound golf balls for games. Two-piece solid golf balls occupy the majority of the market because they have superior flight performance and durability compared to thread-wound golf balls, but thread-wound in terms of feel at impact and controllability on approach shots. Inferior to golf balls.

In recent years, a soft two-piece golf ball has been proposed for a two-piece solid golf ball in order to obtain a feeling and controllability at the time of hitting similar to a thread wound golf ball. However,
In order to obtain such a two-piece golf ball, it is necessary to use a soft core or cover, which reduces the resilience performance of the ball, thereby reducing the flight distance and durability of the two-piece solid golf ball. Also decrease.

Accordingly, various three-piece solid golf balls have been proposed in which an intermediate layer is provided between a core and a cover of a two-piece solid golf ball to form a three-piece, and the feel and controllability at the time of impact are improved without impairing flight performance. (JP-A-6-142228, JP-A-8-322962, JP-A-9-239068, etc.). These are trying to make the feel and controllability at the time of impact closer to a thread-wound golf ball by employing a three-piece structure in which the hardness and hardness distribution of the core, the intermediate layer and the cover are optimized. For example, Japanese Unexamined Patent Publication
No. 142228 discloses a three-piece solid golf ball in which a cover is coated on a two-layer core composed of an inner core and an outer core, wherein the outer core has a Shore D hardness of 30 to 50 and a flexural modulus of 200 to 400 MPa. A cover having a Shore D hardness of 55 to 68 and a flexural modulus of 200 to 450 MPa is disclosed. However, in this golf ball, since the cover is set harder than the intermediate layer (outer layer core), controllability is poor.

Japanese Patent Application Laid-Open No. 8-322962 discloses a three-piece solid golf ball comprising a core and a two-layer cover, in which the core has a compression deformation of 3.5 to 6.5 mm (a load of 10 kg to 130 kg).
And the inner layer cover has a flexural modulus of elasticity of 3,500 to 6,000 kgf / cm ²
The outer layer cover has a bending elastic modulus of 2,300 to 5,500 kgf / cm ²
And the flexural modulus of the outer cover is lower than that of the inner cover by 50 kgf / cm ² or more. That is, by softening the outermost layer of the cover, an attempt was made to improve controllability, but the cover was not sufficiently soft and controllability was not sufficiently improved.
Moreover, the feel at the time of impact is poor because the hardness of the core is not optimized.

Japanese Patent Application Laid-Open No. 9-239068 discloses a three-piece solid golf ball comprising a core, an intermediate layer and a cover, wherein the core has a center hardness of 75 or less and a core surface hardness of JIS-C. Hardness is 85 or less, and the middle layer is J
It discloses that the cover is 5 or more in IS-C hardness and the cover is 5 or more softer than the intermediate layer. In this golf ball, since there is a difference in hardness between the center and the surface of the core, the deformation is large, and there is a problem in feeling and controllability at the time of hitting.

[0007] There is an increasing demand for golf balls that improve the above-mentioned drawbacks of golf balls, improve flight performance, and have excellent feel and controllability when hitting.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional three-piece solid golf ball, and has a good flight performance with a driver and a good feel at the time of hitting. It is an object of the present invention to provide a golf ball excellent in controllability and feeling when hit.

[0009]

The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that in a three-piece solid golf ball having an intermediate layer provided between a core and a cover, the hardness distribution and the initial hardness of the core are reduced. By defining the deformation amount from the state of applying a load of 10 kgf to the final load of 130 kgf, the hardness of the intermediate layer and the cover and the hardness difference within a specific range, the flight performance with the driver and the feeling at impact are good As a result, it has been found that a golf ball excellent in controllability on iron shots and feeling on impact can be obtained, and the present invention has been completed.

That is, the present invention provides a three-piece solid golf ball comprising a core (1), an intermediate layer (2) formed on the core, and a cover (3) covering the intermediate layer. The hardness is 65 to 83 in JIS-C hardness, the core has a deformation amount of 2.8 to 5.3 mm from the state of applying an initial load of 10 kgf to the time of applying a final load of 130 kgf, from the center to the surface of the core. Is approximately constant, the intermediate layer has a Shore D hardness of 63 to 70, and the cover has a Shore D hardness of 45.
And the hardness difference between the intermediate layer and the cover is Shore D.
The present invention relates to a three-piece solid golf ball having a hardness of 3 to 20.

The three-piece solid golf ball of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of a three-piece solid golf ball of the present invention. In the three-piece solid golf ball of the present invention, the intermediate layer (2) is formed on the core (1), and the cover (3) is formed on the intermediate layer (2). The core (1) is a rubber composition containing a base rubber, a co-crosslinking agent, an organic peroxide, an organic sulfur compound, a filler if necessary, an antioxidant, and the like, which is used for an ordinary solid core. By heating and compression vulcanization under the following conditions.

As the base rubber used in the present invention, natural rubber and / or synthetic rubber conventionally used for solid golf balls are used, and particularly, at least 40% or more of cis-1,4-bonds, preferably A so-called high cis polybutadiene rubber having 80% or more is preferred, and if desired, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (EPD)
M) and the like.

The co-crosslinking agent is not particularly limited, but may be an α, β-C 3-8 carbon atom such as acrylic acid or methacrylic acid.
Monovalent or divalent metal salts of unsaturated carboxylic acids such as zinc and magnesium are preferred, and zinc acrylate which imparts particularly high resilience is preferred. The amount is 20 to 32 parts by weight, preferably 22 to 30 parts by weight, based on 100 parts by weight of the base rubber. If the amount is less than 20 parts by weight, it becomes too soft and rebound is deteriorated, and the flight distance is reduced. If the amount is more than 32 parts by weight, it becomes too hard and the feeling is deteriorated.

Organic peroxides act as crosslinkers or hardeners, for example, dicumyl peroxide, 1,1-bis (t-
(Butylperoxy) -3,3,5-trimethylcyclohexane,
2,5-dimethyl-2,5-di (t-butylperoxy) hexane,
Di-t-butyl peroxide is preferred, with dicumyl peroxide being preferred. Compounding amount is polybutadiene 100
0.5 to 3.0 parts by weight, preferably 0.8 to 2.5 parts by weight based on parts by weight
Parts by weight. If it is less than 0.5 parts by weight, it becomes too soft and rebound becomes worse, resulting in a shorter flight distance. If it exceeds 3.0 parts by weight, it will be too hard and the feeling will be poor.

Examples of the organic sulfur compound include diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, dithiobenzoyl polysulfide, and the like. Diphenyl disulfide is preferred from the viewpoint of resilience. The compounding amount is 0.05 with respect to 100 parts by weight of the base rubber.
To 5.0 parts by weight, preferably 0.1 to 4.0 parts by weight. 0.05
If the amount is less than part by weight, the amount is too small to exert the effect of the organic sulfur compound, and if the amount exceeds 5.0 parts by weight, the effect is not further improved.

Further, the core of the golf ball of the present invention includes a filler (eg, zinc oxide, barium sulfate, calcium carbonate, etc.), a high specific gravity metal powder (eg, tungsten powder,
Molybdenum powder, etc.), an antioxidant or a peptizer, and other components that can be generally used for producing a core of a solid golf ball may be appropriately compounded. The antioxidant is 0.2 to
0.5 parts by weight is preferred.

The core (1) is obtained by kneading the rubber composition described above,
It can be obtained by vulcanization molding in a mold. The golf ball core of the present invention has a surface hardness of 6 in JIS-C hardness.
It is 5-83, preferably 67-81. Core surface hardness is 65
If it is smaller than this, the resilience decreases, and if it is larger than 83, the feel at impact is hard and poor. Further, the hardness from the center to the surface of the core is almost constant in JIS-C hardness, and the hardness difference of an arbitrary portion from the center to the surface of the core is 5 or less, preferably 3 or less in JIS-C hardness. If the difference in hardness of any portion from the center to the surface is larger than 5, the resilience decreases, the launch angle decreases, and the flight distance decreases. In addition, the hardness inside the core other than the surface of the core generally means the hardness measured by cutting the core into two equal parts.

Further, the core of the golf ball of the present invention has an amount of deformation of 2.8 to 5.3 mm, preferably 3.0 to 5.0 mm, from a state of applying an initial load of 10 kgf to a state of applying a final load of 130 kgf.
More preferably 3.1 to 4.9 mm. If it is smaller than 2.8 mm, the core becomes too hard, and the feeling of the obtained golf ball at the time of hitting is deteriorated. If it is larger than 5.3 mm, the core becomes too soft, the rebound is deteriorated, and the flight distance is reduced.

The shaping of the core so as to satisfy the above requirements can be achieved by adjusting the vulcanization conditions. Specifically, the aforementioned rubber composition is heated at a low temperature of 130 to 150 ° C. for 10 to
After vulcanization for 37 minutes, then at a high temperature of 150-180 ° C for 3-20
The above hardness and deformation can be obtained by vulcanization molding for a minute. In the present invention, the core diameter is 32.7 to
It is 38.4 mm, preferably 33.0 to 38.0 mm. If it is smaller than 32.7 mm, the effect such as resilience of the core is not exhibited, and the resilience of the obtained golf ball is deteriorated.If it is larger than 38.4 mm, one or both of the intermediate layer and the cover are too thin, and the intermediate layer and The effect of the cover cannot be obtained. An intermediate layer (2) is then formed on the core (1) obtained as described above.

In the present invention, the intermediate layer (2) has a Shore D hardness of 63 to 70, preferably 64 to 68. If the Shore D hardness is less than 63, the golf ball becomes too soft, the rebound deteriorates, and the flight distance decreases. If the Shore D hardness is larger than 70, the resin becomes too hard, an appropriate amount of deformation cannot be obtained, the resilience is reduced, and the feel at the time of impact is also poor. Also the middle layer
(2) preferably has a thickness of 1.0 to 2.5 mm, preferably 1.2 to 2.2 mm, more preferably 1.4 to 2.0 mm. If the thickness is less than 1.0 mm, the effect of the intermediate layer cannot be sufficiently obtained, and if the thickness is more than 2.5 mm, the feeling at the time of impact is deteriorated. Furthermore, the middle layer
(2) has a specific gravity of 1.2 or more, preferably 1.2 to 1.5. When the specific gravity is less than 1.2, the moment of inertia decreases, and the flight performance deteriorates.

The material used for the intermediate layer (2) of the present invention is as follows:
There is no particular limitation as long as it satisfies the above characteristics, but a thermoplastic resin is preferred in terms of productivity, resilience, durability and the like. Examples of thermoplastic resins include, in addition to ionomer resins, polyethylene resins, polyamide resins, polyurethane resins, 1,2-polybutadiene, styrene
-Butadiene copolymer or the like, or a mixture thereof. As the ionomer resin, ethylene- (meth)
What neutralized a part of carboxylic acid in the copolymer of acrylic acid with a metal ion, or its mixture is used. As the metal ions to be neutralized, alkali metal ions,
For example, Na ion, K ion, Li ion, etc .; divalent metal ion, eg, Zn ion, Ca ion, Mg ion, etc .;
Valent metal ions, for example, Al ions, Nd ions and the like; and mixtures thereof, of which Na ions, Zn ions, Li ions and the like are often used because of their resilience, durability and the like. Specific examples of the ionomer resin include, but are not limited to, Himilan 1555, 1557, 1605, 165
2, 1705, 1706, 1707, 1855, 1856 (manufactured by DuPont Mitsui Polychemicals), Surlyn AM7317, AM7318, 8320 (manufactured by DuPont, USA), IOTEC 7010, 8000 (manufactured by Exxon), etc. Can be. Examples of the polyethylene resin include UJ960 (manufactured by Mitsubishi Chemical Corporation). As polyamide resin, diamide E40-S3, E47-S3, E55-S3
(Manufactured by Daicel Huls), Pebax 5533SN00, 40
33SN00, 2533SN00 (manufactured by Atochem) and the like. Elastane ET880, ET890 as polyurethane resin
(Manufactured by Takeda Birdish), Pandex T-8180 (manufactured by Dainippon Ink and Chemicals), and the like.

The composition for the intermediate layer (2) contains a filler for adjusting the specific gravity in addition to the above-mentioned thermoplastic resin such as the ionomer resin, or a material mainly containing a mixture thereof. You may. Examples of the filler include inorganic salts (specifically, zinc oxide, barium sulfate, and calcium carbonate), high specific gravity metal powder (for example, tungsten powder, molybdenum powder, and the like), and a mixture thereof.
Further, the composition for the intermediate layer (2) of the present invention may contain, in addition to the above-mentioned components, additives usually used for golf ball covers as long as the desired properties are not impaired.

The intermediate layer (2) of the present invention can be formed by using a generally known method used for forming a cover of a golf ball, and is not particularly limited. The composition for the intermediate layer is preliminarily formed into a hemispherical shell-shaped half shell, and a solid core is wrapped using two of them, followed by pressure molding, or injection molding of the intermediate layer composition directly on the core. A method of wrapping the core may be used. Next, in the present invention, the cover (3) is coated on the intermediate layer (2).

In the present invention, the cover (3) has a Shore D hardness of 45 to 62, preferably 50 to 60, more preferably 55 to 60. If the Shore D hardness is less than 45, the resilience will be poor and the flight distance will be reduced. If the Shore D hardness is greater than 62, the feel at the time of impact becomes hard and poor, and the controllability on approach shots is poor. The difference between the hardness of the intermediate layer and the hardness of the cover is 3 to 20, preferably 3 to 18, and more preferably 5 to 17 in Shore D hardness. If the difference between the hardness of the intermediate layer and the hardness of the cover is smaller than 3, there is no difference between the intermediate layer and the cover, and the effect of the intermediate layer is small. If it is larger than 20, the intermediate layer becomes too hard with respect to the cover, and the feeling becomes worse. The cover (3) preferably has a thickness of 1.0 to 2.5 mm, preferably 1.0 to 2.2 mm, more preferably 1.4 to 2.0 mm. If it is thinner than 1.0 mm, the effect of the cover cannot be sufficiently obtained, and if it is thicker than 2.5 mm, the feeling at the time of hitting deteriorates. Further, the cover (3) has a specific gravity of less than 1.2, preferably 0.8-1.2, more preferably 0.9-1.1. When the specific gravity is 1.2 or more, the difference in specific gravity of the intermediate layer becomes small, and the effect of the intermediate layer cannot be sufficiently exhibited.

The material used for the composition for the cover (3) of the present invention is not particularly limited as long as it satisfies the above-mentioned properties, but is usually used as a cover material for a solid golf ball. A material is used, and a thermoplastic resin is preferable. Examples of the thermoplastic resin include an intermediate layer (2)
And the like, ionomer resins, polyethylene resins, polyamide resins, polyurethane resins, 1,2-polybutadiene, styrene-butadiene copolymers, and the like, or mixtures thereof.

In the present invention, in addition to the above-mentioned resin as a main component, the above-mentioned cover composition may contain, if necessary,
Fillers such as barium sulfate and calcium carbonate, coloring agents such as titanium dioxide, and other additives such as dispersants, anti-aging agents, ultraviolet absorbers, light stabilizers, fluorescent materials or fluorescent brighteners, etc. Although it may be contained within a range that does not impair the desired properties of the ball cover, usually, the compounding amount of the colorant is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the cover resin.

The method for coating the cover (3) is the same as the method for coating the intermediate layer. When molding the cover, a large number of depressions called dimples are formed on the surface as necessary. The golf ball of the present invention is usually put on the market after being subjected to a paint finish, a marking stamp, or the like, in order to enhance aesthetic appearance and commercial value. still,
The three-piece solid golf ball of the present invention has a diameter of not less than 42.67 and a weight of not more than 45.93 g based on the golf ball rules.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 6 and Comparative Examples 1 to 8) Preparation of Core A rubber composition for a core having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) was kneaded with a kneading roll. , By hot pressing under the vulcanization conditions shown in the table, diameter 35.1
A spherical core of mm was obtained. The hardness distribution and the amount of compressive deformation of the obtained core were measured, and the results are shown in Table 4 (Example) and Table 5 (Comparative Example). The test method was performed as described below.

[0030]

[Table 1]

[0031]

[Table 2]

Preparation of Intermediate Layer and Cover Composition The materials having the formulations shown in Table 3 below were mixed with a twin-screw kneading extruder to prepare a pellet-shaped intermediate layer and cover composition. Extrusion conditions are screw diameter 45mm,
The screw speed was 200 rpm, the screw L / D = 35, and the blend was heated to 200-260 ° C. at the die position of the extruder. The Shore D hardness of the resulting intermediate layer and cover composition was measured, and the results are shown in Tables 4 and 5.
The test method was performed as described below.

[0033]

[Table 3]

(Note 3) Sodium ion neutralized ethylene-methacrylic acid copolymerized ionomer resin manufactured by Mitsui Dupont Polychemical Co., Ltd. (Note 4) Sodium ion neutralized ethylene-methacrylic acid manufactured by Mitsui Dupont Polychemical Co., Ltd. Copolymerized ionomer resin (Note 5) Zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui Dupont Polychemicals Co., Ltd. (Note 6) Zinc ion neutralized ethylene manufactured by Mitsui DuPont Polychemicals Methacrylic acid-acrylic acid ester terpolymer ionomer resin (Note 7) Zinc ion neutralized ethylene resin manufactured by DuPont in the United States-Methacrylic acid copolymer ionomer resin manufactured by DuPont (Note 8) Sodium ion neutralized ethylene manufactured by DuPont in the United States Methacrylic acid copolymerized ionomer resin (Note 9) Sodium ion neutralized ethylene-methacrylic acid copolymer manufactured by DuPont Combined ionomer resin

Formation of Intermediate Layer An intermediate layer having a thickness of 1.9 mm was formed by injection molding the compounding material for an intermediate layer shown in Table 4 (Example) and Table 5 (Comparative Example) on the core. . Table 4 (Example) and Table 5 (Comparative Example) similarly show the Shore D hardness of the obtained intermediate layer. The test method was performed as described below.

Preparation of Golf Ball The cover compositions shown in Table 4 (Examples) and Table 5 (Comparative Examples) were injection molded on the resulting intermediate layer. Then, the same treatment as that of a normal golf ball such as deburring, paint pretreatment, and paint was performed to finish the golf ball, which had a weight of 45.4 g and a diameter of 42.7 mm. The obtained golf ball was evaluated for the amount of compressive deformation, the flight distance, the feel at impact (driver, 5 iron and sand wedge) and the controllability (5 iron and sand wedge). (Example)
And Table 5 (Comparative Example). The test method was performed as described below.

(Test Method) Amount of Compressive Deformation (Core and Ball) The amount of deformation from the state where an initial load of 10 kgf was applied to the core and the ball until the final load of 130 kgf was applied was measured. Shore D hardness of cover A hot press-formed sheet having a thickness of about 2 mm produced from each cover composition is stored at 23 ° C for 2 weeks, and then three or more sheets are laminated according to ASTM D-2240, and the shore is subjected to Shore D hardness. It is measured using a D hardness meter. Flying distance A No. 1 wood club (W # 1, driver) was attached to a swing robot manufactured by True Temper, a golf ball was hit at a head speed of 45 m / sec, and a carry (distance to a falling point) was measured as a flying distance. Feeling and controllability at the time of hitting It was evaluated by an actual hitting test by 10 professional golfers. The feeling at the time of impact was evaluated by an actual hit test with a driver, and the controllability was evaluated by an actual hit test with a 30 yard approach shot with a sand wedge. The criteria were as follows. Judgment criteria 〇… Eight or more answered that they were good. Δ: 7 to 4 persons answered that it was good. ×: Three or less persons answered that they were good.

(Test results)

[Table 4]

[0039]

[Table 5]

From the above results, the golf balls of Examples 1 to 6 of the present invention have a longer flight distance than the golf balls of Comparative Examples 1 to 8, and have a feeling and controllability with a driver and an iron shot. It can be seen that both are excellent three-piece solid golf balls.

On the other hand, in the golf ball of Comparative Example 1, the surface hardness of the core is low and the amount of compressive deformation is large, so that the resilience is reduced and the flight distance is reduced. In the golf balls of Comparative Examples 2 and 3, the hardness distribution of the core is wide, so that the resilience is reduced and the flight distance is reduced. In the golf ball of Comparative Example 4, the core has a high surface hardness, so that the feel at the time of hitting is poor. In the golf ball of Comparative Example 5, the feel at impact is poor because the hardness of the intermediate layer is high. In the golf ball of Comparative Example 6, since the hardness of the intermediate layer was low, the resilience was reduced and the flight distance was reduced. In the golf ball of Comparative Example 7, the feel at the time of hitting was poor because the cover had high hardness. In the golf ball of Comparative Example 8, since the cover had low hardness, the resilience was reduced and the flight distance was reduced.

[0042]

The three-piece solid golf ball of the present invention has a core hardness distribution and an amount of deformation from a state where an initial load of 10 kgf is applied to a state where a final load of 130 kgf is applied.
By defining the hardness and the hardness difference between the intermediate layer and the cover in a specific range, it is possible to improve the flight performance with a driver, the feeling at the time of hitting, the controllability at the time of iron shot, and the feeling at the time of hitting. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a golf ball of the present invention.

[Explanation of symbols]

 1 ... core 2 ... middle layer 3 ... cover

Claims (5)

[Claims] 1. A core (1) and an intermediate layer formed on the core
In a three-piece solid golf ball comprising (2) and a cover (3) covering the intermediate layer, a state in which the surface hardness of the core is 65 to 83 in JIS-C hardness and the core is loaded with an initial load of 10 kgf From the center to the surface of the core is substantially constant, and the intermediate layer has a Shore D hardness of 63 to 70.
A three-piece solid golf ball, wherein the cover has a Shore D hardness of 45 to 62, and the hardness difference between the intermediate layer and the cover is 3 to 20 in Shore D hardness. 2. The three-piece solid golf ball according to claim 1, wherein a hardness difference between an arbitrary portion from the center of the core (1) to the surface thereof is 5 or less in JIS-C hardness. 3. The three-piece solid golf ball according to claim 1, wherein the intermediate layer (2) has a specific gravity of 1.2 or more, and the cover has a specific gravity of less than 1.2. 4. The core (1) comprises a cis-
20 to 32 parts by weight of a co-crosslinking agent, based on 100 parts by weight of cis-1,4-polybutadiene having at least 40% of 1,4-bonds,
Organic peroxide 0.5 to 3.0 parts by weight, organic sulfur compound 0.05 to 5
The three-piece solid golf ball according to claim 1, comprising a rubber composition containing parts by weight. 5. The intermediate layer (2) has a thickness of 1.0 to 2.5 mm, and the cover (3) has a thickness of 1.0 to 2.5 mm.
A three-piece solid golf ball as described.