JP2001346909A - Multipiece solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality multipiece solid golf ball which can achieve high-inertia moment, is enhanced in the stability during flying of the golf ball, is increased in distance, is improved in rolling stability in putting and has an extremely soft and good feeling and excellent durability. SOLUTION: This multipiece solid golf ball has a solid core, at least one intermediate layer coating this core and at least one cover coating this intermediate layer. The amount of deformation A (mm) when load of 100 kg is applied on the solid core and the amount of deformation B (mm) when load of 100 kg is applied to a spherical body obtained by coating the intermediate layer on the circumference of the core satisfy a relation B/A=1.0 to 1.5, the specific gravity of the intermediate layer is greater than the specific gravity of the solid core and the member hardness (JIS-C) of the intermediate layer is lower than the surface hardness (JIS-C) of the solid core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-piece solid golf ball having a three-layer structure or more having a solid core, at least one intermediate layer, and at least one cover.

Conventionally, many two-piece solid golf balls have a ballistic trajectory called a so-called ball ball for both driver shots and iron shots as compared with thread-wound golf balls. There is an advantage that the total flight distance is increased due to the large number of flights.

[0003] On the other hand, two-piece solid golf balls tend to be harder to stop on the green because of less spin on iron shots than thread wound golf balls, and tend to be inferior in controllability.

[0004] On the other hand, a golf ball is required to have a soft feel at the time of hitting as the flight distance increases, otherwise the commercial value is impaired. In general, thread-wound golf balls have structural characteristics that are softer and provide a better feel when compared to two-piece solid golf balls.

For this reason, it is common practice to soften the ball structure of a two-piece solid golf ball comprising a core and a cover in order to achieve a soft feel when hit.

[0006] Such a soft type two-piece solid golf ball generally uses a soft core, but if the core is too soft, the resilience is reduced, the flight performance is reduced, and the durability is also significantly reduced. In addition, not only is it not possible to obtain excellent flight performance and durability, which are the characteristics of a two-piece solid golf ball, but also it becomes difficult to endure actual use.

Recently, in order to solve such problems, many three-piece solid golf balls having an intermediate layer between a core and a cover have been proposed (Japanese Patent Laid-Open No. 7-2).
4084, JP-A-6-23069, JP-A-4-244174, JP-A-9-10358, JP-A-9-313543 and the like.

However, even in these proposals,
If the cover and the intermediate layer are formed softly, the feeling becomes soft, but the flight distance at the time of a full shot with a driver is reduced. Conversely, when trying to obtain a flight distance, the cover and the intermediate layer must be formed hard, resulting in poor hit feeling at the time of approach shot and putting, and a decrease in spin performance at iron shot. There is a problem.

On the other hand, for the purpose of increasing the moment of inertia and improving flight performance and controllability at approach shot, a high specific gravity filler is added to a cover or an intermediate layer of a three-piece solid golf ball. However, if the filler is added in a high proportion, there is a problem in that the resilience is rather lowered, the flight distance is reduced, and the hit feeling is inferior.

As described above, the multi-piece solid golf balls having three or more pieces to date do not have satisfactory performance in any case, and further improvement is desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the moment of inertia in a multi-piece solid golf ball having a three-layer structure or more having a solid core, at least one intermediate layer, and at least one cover. Improves the stability of the golf ball during flight,
It is an object of the present invention to provide a high-quality multi-piece solid golf ball having an increased flight distance, improved rolling stability during putting, and excellent controllability.

[0012]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has provided a solid core, at least one intermediate layer and at least one cover. In a multi-piece solid golf ball having three or more layers, it has been found that forming the intermediate layer thin and soft and increasing the specific gravity of such an intermediate layer is effective in increasing the moment of inertia.

That is, in a multi-piece solid golf ball including a solid core, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer, (i) 100 kg of the solid core is added to the solid core. The amount of deformation A (mm) when a load is applied, and the amount of deformation B (mm) when a load of 100 kg is applied to the spherical body having the core covered with the intermediate layer, B / A = 1. 0-1.
(Ii) the thickness of the intermediate layer is 0.3
~ 1.5 mm and the hardness of the intermediate layer (J
IS-C) being lower than the surface hardness (JIS-C) of the solid core, (iii) making the specific gravity of the intermediate layer larger than that of the solid core, and (iv) preferably making the intermediate layer 1,4. -By forming with a rubber composition mainly composed of a rubber base material containing cis-polybutadiene as a main component, a high moment of inertia can be achieved in combination with these requirements (i) to (iv); The stability of the ball during flight during driver shots is improved, the flight distance is increased,
It was found that a high-quality multi-piece solid golf ball with stable rolling properties on approach shots and putting, improved controllability, soft good feeling and excellent durability on continuous hits can be obtained. The invention has been completed.

Accordingly, the present invention provides a multi-piece solid golf ball comprising (1) a solid core, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer. Deformation amount A (m) when a load of 100 kg is applied to the solid core
m) and a spherical body having an intermediate layer coated around the core.
The amount of deformation B (mm) when a load of 00 kg is applied is
B / A = 1.0-1.8 is satisfied, the thickness of the intermediate layer is 0.3-1.5 mm, the specific gravity of the intermediate layer is larger than the specific gravity of the solid core, and The member hardness (JIS-C) is the surface hardness of the solid core (JIS
-C); (2) a specific gravity difference between the specific gravity C of the intermediate layer and the specific gravity D of the solid core (CD) ) Is 0.03 or more, and the hardness difference (EF) between the surface hardness E of the solid core and the member hardness F of the intermediate layer.
The multi-piece solid golf ball according to (1), wherein the intermediate layer is made of a rubber composition mainly composed of a rubber base material containing 1,4-cis-polybutadiene as a main component. (1) The multi-piece solid golf ball according to (2), and (4) the cover has a thickness of 1
A multi-piece solid golf ball according to (1), (2) or (3), which is formed from a thermoplastic resin material having a specific gravity of 0.9 to 5 mm.

Hereinafter, the present invention will be described in more detail. The multi-piece solid golf ball G of the present invention
For example, as shown in FIG. 1, a solid core 1, an intermediate layer 2 covering the core 1, and a cover 3 covering the intermediate layer 2 are provided. In this case, each of the core 1, the intermediate layer 2, and the cover 3 has at least one layer, so that a multi-piece solid golf ball having a three-layer structure or more can be formed.

The solid core 1 can be formed from a rubber composition mainly composed of a base rubber mainly composed of polybutadiene rubber, polyisoprene rubber, natural rubber, and silicone rubber. For this purpose, polybutadiene rubber is preferred. Such polybutadiene rubber has a cis structure of at least 40% or more,
Preferably, cis-1,4-polybutadiene having 90% or more is suitable. In the base rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, and the like can be appropriately blended with the above-mentioned polybutadiene, but the resilience of the golf ball is improved by increasing the polybutadiene rubber component. Therefore, the rubber component other than polybutadiene is preferably not more than 10 parts by mass based on 100 parts by mass of polybutadiene.

The rubber composition may contain, as a crosslinking agent, zinc salts of unsaturated fatty acids such as zinc methacrylate and zinc acrylate, magnesium salts, and ester compounds such as trimethylpropane methacrylate. Particularly, zinc acrylate is preferable because of its high resilience. The compounding amount of these crosslinking agents is preferably 15 to 40 parts by mass based on 100 parts by mass of the base rubber.

The rubber composition usually contains dicumyl peroxide or a mixture of dicumyl peroxide and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane. Contains a sulfuric acid,
The compounding amount of the vulcanizing agent is 0.1 to 100 parts by mass of the base rubber.
It can be 1 to 5 parts by mass.

The rubber composition may further include, if necessary,
Zinc oxide, barium sulfate, and the like can be blended as an antioxidant and a filler for adjusting specific gravity. The blending amount of these fillers is 0 to 130 parts by mass with respect to 100 parts by mass of the base rubber.

The core rubber composition is kneaded using a conventional kneader (eg, Banbury mixer, kneader, roll, etc.), and the obtained compound is filled in a core mold, and injection molding or compression is performed. It can be formed by molding.

The solid core thus obtained is:
The diameter is preferably 25 to 40 mm, more preferably 27 to 39 mm, still more preferably 30 to 38 mm, the weight is 10 to 40 g, preferably 15 to 35 g, more preferably 20 to 34 g, and the specific gravity is 1 to 1.4,
Preferably 1.1-1.3, more preferably 1.15
1.3.

The amount of deformation A when a load of 100 kg is applied to the solid core is 2.5 mm or more, preferably 2.5 to 6.0 mm, more preferably 2.8 to 5 mm. If the deformation amount A of the core is too small, the feeling may be hard, while if it is too large, the resilience may decrease. The surface hardness (JIS-C) of the solid core is 60 to 90, preferably 65 to 85,
More preferably, it is 70 to 83.

The core may have a single-layer structure made of one kind of material or a multi-layer structure made up of two or more layers made of different materials.

In the present invention, at least one, preferably one or two intermediate layers 2 are formed around the core 1.

The material for forming the intermediate layer is not particularly limited, and polyester elastomers, polyamide elastomers, styrene elastomers, polyurethane elastomers, olefin elastomers, mixtures thereof, and rubber materials can be used. However, it is particularly preferable to use a rubber material. This is because when the intermediate layer is formed thin, the intermediate layer is formed thicker (larger) in advance, and then the surface is polished to a desired size (thickness).

The rubber material for forming such an intermediate layer is preferably made of a rubber composition mainly composed of a base rubber mainly composed of 1,4-cis polybutadiene rubber as in the case of the solid core. . In this case, the rubber composition may contain a crosslinking agent, a co-crosslinking agent, an inert filler, and the like, in addition to the rubber component. As the crosslinking agent, zinc methacrylate, zinc acrylate, or another unsaturated fatty acid is used. Salt, magnesium salt, ester compound such as trimethylpropane methacrylate, etc. in an amount of 5 to 100 parts by mass of the base rubber.
20 parts by mass, preferably 5 to 15 parts by mass.

In the present invention, it is preferable to add a high specific gravity inorganic filler to the rubber composition of the intermediate layer. By adding a high specific gravity inorganic filler to the intermediate layer, the moment of inertia can be increased.

The average particle size of the inorganic filler is usually 0.1.
It is from 0.1 to 100 µm, preferably from 0.1 to 10 µm, more preferably from 0.1 to 1.0 µm. If the average particle size is too small or too large, the dispersibility at the time of filling will be deteriorated, and the effect of the present invention may not be achieved.

The inorganic filler is not particularly limited, and includes, for example, barium sulfate, titanium dioxide, calcium carbonate, tungsten and the like, and one of these may be used alone or in combination of two or more. Among them, barium sulfate and tungsten are particularly preferable.

The amount of the inorganic filler to be added is 10 to 60 parts by mass relative to 100 parts by mass of the rubber composition forming the intermediate layer.
Preferably 20 to 60 parts by mass, more preferably 30 to 6 parts by mass.
0 parts by mass.

The method for coating the intermediate layer around the core is not particularly limited, and ordinary injection molding or compression molding can be employed.
In the present invention, it is difficult to form the intermediate layer thinner only by injection molding or compression molding. Therefore, a thicker (larger) intermediate layer is formed around the solid core in advance, and then the desired size is obtained. (Thickness) is preferably adjusted by surface polishing or the like.

The intermediate layer of the present invention has a member strength (JIS
-C hardness) is 10 to 65, preferably 15 to 60, and more preferably 20 to 55. Here, the member strength is J
This is a value obtained by measuring a test piece made of the intermediate layer composition in accordance with ISK6301 with a JIS-C type tester. In this case, the member hardness (JIS-C) of the intermediate layer needs to be lower than the surface hardness (JIS-C) of the solid core.
Specifically, the hardness difference (EF) between the surface hardness E of the solid core and the member hardness F of the intermediate layer is 5 or more, preferably 5 to 4
0, more preferably 10 to 35. If the hardness of the member of the intermediate layer is higher than the surface hardness of the solid core, the feel at impact becomes hard because the high specific gravity filler is added.

The thickness of the intermediate layer is 0.3 to 1.5 mm
, Preferably 0.4 to 1.2 mm, more preferably 0.4 to 0.9 mm, and specific gravity of 1.1 or more, preferably 1.1 to 1.5, more preferably 1.2 to 1.4
5 The specific gravity of the intermediate layer needs to be larger than the specific gravity of the solid core, and the specific gravity difference (CD) between the specific gravity C of the intermediate layer and the specific gravity D of the solid core is 0.03 or more,
Preferably 0.05 or more, more preferably 0.05 to
0.2. If the specific gravity of the intermediate layer is smaller than the specific gravity of the solid core, the moment of inertia cannot be increased.

In the present invention, the amount of deformation B (mm) when a load of 100 kg is applied to the spherical body with the intermediate layer coated around the core is 2.5 to 6.5 mm, preferably 2.8 to 6.5. 6.0 mm, more preferably 3 to 5 mm.
The amount of deformation A (mm) when a load of kg is applied is B /
It is necessary to satisfy the relationship of A = 1.0 to 1.8,
Preferably 1.0 to 1.5, more preferably 1.0 to 1.5
1.3, more preferably 1.0 to 1.2. B / A
If is too small, the feel on impact will be hard, while if too large, the resilience and durability will decrease, and none of the objects and effects of the present invention can be achieved.

Next, a cover 3 is formed around the intermediate layer 2 in at least one layer, preferably one layer or two layers.

The cover can be formed by using a usual thermoplastic resin as a main material, for example, an ionomer resin,
Examples include polyester-based elastomers, polyamide-based elastomers, styrene-based elastomers, polyurethane-based elastomers, olefin-based elastomers, and mixtures thereof. Of these, ionomer resins are preferred. Specifically, "Himilan" (manufactured by Dupont Mitsui Polychemicals), "Surlyn" (manufactured by Dupont),
Commercial products such as "IOTEC" (manufactured by Exxon) can be used. In addition, if necessary, cover material
An absorbent, an antioxidant, and a dispersant such as metal soap can also be added.

The method for coating the cover around the intermediate layer is not particularly limited, and ordinary injection molding or compression molding can be employed.

The cover thus formed preferably has a Shore D hardness of 40 to 70, more preferably 45 to 70.
65.

The thickness of the cover is 1 to 5 mm, preferably 1.2 to 4 mm, more preferably 1.3 to 3 mm.
It is more preferably 1.4 to 2.5 mm, and the specific gravity of the cover is 0.9 or more, preferably 0.92 to 1.3, more preferably 0.93 to 1.2.

The amount of deformation when a load of 100 kg is applied to the spherical body (that is, the entire ball) in which the cover is covered around the intermediate layer is preferably 2.6 to 5.5 mm, more preferably 2. 8 to 4.8 mm.

The multi-piece solid golf ball of the present invention has a moment of inertia measured by the following method of 82 g ·
cm ² or more, preferably 82 to 90 g · cm ² , more preferably 82 to 85 g · cm ² . If the moment of inertia is too small, the stability of the golf ball during flight may be reduced, or the ball may be poorly rolled during putting.

Here, the moment of inertia of the golf ball is a calculated value obtained from the diameter (thickness) and specific gravity of each layer, and can be obtained by the following equation, assuming that the ball is spherical. In this case, the calculation assumes that the ball is spherical,
Actually, since there are many dimples on the ball surface, the specific gravity of the outer cover layer is smaller than the specific gravity of the actual outer cover resin.
Using this, the moment of inertia M is calculated. M = (π / 5880000) × ｛(r1-r2) × D1
^{5 + (r2-r3) ×} D2 5 + r3 × D3 5} wherein, M: moment of inertia ^{(g · cm 2), r1} : the core density, D1: core diameter, r2: inner cover layer specific gravity, D
2: the inner cover layer diameter (diameter of a sphere after forming the inner cover layer on the core; mm), r3: virtual specific gravity of the outer cover layer, D3: outer cover layer diameter (ball diameter; mm). ]

The multi-piece solid golf ball of the present invention has the above-mentioned constitutions, and together, can achieve a high moment of inertia, enhance the stability of the golf ball during flight, and increase the flight distance. In addition, the rolling stability at the time of putting is improved, the controllability is excellent, the soft feeling is good and the durability is excellent.

Incidentally, the golf ball of the present invention has a large number of dimples formed on the surface thereof, and the surface can be subjected to a finishing treatment such as painting and stamping as necessary. Further, the ball diameter and weight can be formed to a diameter of not less than 42.67 mm and a weight of not more than 45.93 g in accordance with the R & A golf rules.

[0045]

According to the present invention, a high moment of inertia can be achieved, the stability of the golf ball during flight increases, the flight distance increases, the rolling stability during putting improves, and the golf ball is very soft. A high-quality multi-piece solid golf ball having good feeling and excellent durability can be obtained.

[0046]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 to 4, Comparative Examples 1 to 3] A rubber composition for a core having the compounding formulation shown in Table 1 was kneaded with a kneader.
By vulcanizing in a core mold at a temperature of 155 ° C. for about 15 minutes, the following solid cores were prepared.

[0048]

[Table 1] * 1,4-cis-polybutadiene: Nippon Synthetic Rubber, B
R01

The three-pieces of Examples 1 to 4 and Comparative Examples 1 to 3 were formed by forming an intermediate layer material shown in Table 2 and the following cover material around the obtained core by injection molding in combination with the combinations shown in Table 3. A solid golf ball was created. In addition,
The intermediate layers of Examples 1 to 4 and Comparative Example 3 were formed thicker in advance, and were adjusted to a predetermined thickness by polishing.

[0050]

[Table 2] * 1,4-cis-polybutadiene: Nippon Synthetic Rubber, B
R01

Cover material Himilan 1706 50 parts by mass Himilan 1605 50 parts by mass Shore D hardness = 63 Ionomer resin manufactured by DuPont-Mitsui Polychemicals

Next, the obtained Examples 1 to 4 and Comparative Example 1
Various characteristics of golf balls Nos. 1 to 3 were evaluated by the methods described below. Table 3 shows the results. Solid core deformation: expressed as the deformation (mm) of the core when a load of 100 kg was applied to the A core. Deformation amount of spherical body in which solid layer was coated with intermediate layer: Deformation amount (mm) of spherical body when a load of 100 kg was applied to spherical body in which B layer was coated with intermediate layer. Flying performance At a head speed of 45 m / sec (HS45), the club was driven by a driver (# W1) (“PRO230Titan” Loft 10
Degree (Bridgestone Sports Co., Ltd.))
Carry, total flight distance, and carry variation at the time of actual hit [(maximum carry)-(minimum carry)]
Was measured. Inertia moment The moment of inertia was determined from the following equation. M = (π / 5880000) × ｛(r1-r2) × D1
^{5 + (r2-r3) ×} D2 5 + r3 × D3 5} wherein, M: moment of inertia ^{(g · cm 2), r1} : the core density, D1: core diameter, r2: inner cover layer specific gravity, D
2: the inner cover layer diameter (diameter of a sphere after forming the inner cover layer on the core; mm), r3: virtual specific gravity of the outer cover layer, D3: outer cover layer diameter (ball diameter; mm). Stability During Putting Rolling conditions during putting were evaluated by five professional golfers according to the following criteria. ：: good △: slightly poor ×: poor hitting feel Five golfers, driver (# W1), ninth iron (# I9) and putter (#P)
The feel when actually hitting using T) was evaluated according to the following criteria. ○: very soft △: normal ×: hard durable The ball obtained by using a swing robot manufactured by Miyama Co., Ltd. was used as a driver (“PRO230Titan”).
Loft 10 degrees "(Bridgestone Sports Co., Ltd.)
After hitting repeatedly at a head speed of 45 m / sec (HS45) using, the state of the ball surface was relatively evaluated according to the following criteria according to the number of hits. ○: No problem at all △: Destruction relatively early ×: Early destruction

[0053]

[Table 3] * 1: Core + middle layer

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multi-piece solid golf ball according to one embodiment of the present invention.

[Description of Signs] 1 Solid core 2 Intermediate layer 3 Cover G Golf ball

Claims (4)

[Claims] 1. A multi-piece solid golf ball comprising a solid core, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer, wherein a load of 100 kg is applied to the solid core. The amount of deformation A (mm) when applied and the amount of deformation B (mm) when a load of 100 kg is applied to the spherical body with the intermediate layer coated around the core are B / A = 1.0 to 1.8, and the thickness of the intermediate layer is 0.3 to 1.5.
mm, the specific gravity of the intermediate layer is greater than the specific gravity of the solid core, and the member hardness (JIS-C) of the intermediate layer is lower than the surface hardness (JIS-C) of the solid core. ball. 2. A specific gravity difference between the specific gravity C of the intermediate layer and the specific gravity D of the solid core (C−C).
2. The multi-piece solid golf ball according to claim 1, wherein D) is 0.03 or more, and a hardness difference (E-F) between a surface hardness E of the solid core and a member hardness F of the intermediate layer is 5 or more. 3. The multi-piece solid golf ball according to claim 1, wherein the intermediate layer is formed from a rubber composition mainly composed of a rubber base material containing 1,4-cis-polybutadiene as a main component. 4. The multi-piece solid golf ball according to claim 1, wherein said cover is formed of a thermoplastic resin material having a thickness of 1 to 5 mm and a specific gravity of 0.9 or more.