JP3516123B2 - Multi-piece solid golf ball - Google Patents

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 in which a solid core is covered with inner and outer two-layer covers.

[0002]

2. Description of the Related Art Currently,
Various structures of golf balls have been proposed, especially solid golf balls, especially multi-piece solid golf balls in which a solid core is covered with a plurality of layers in terms of flight distance, controllability (spin amount), and feeling. Many proposals have been made (Japanese Patent Laid-Open No. 4-2)
No. 44174, No. 6-142228, No. 7-2408.
No. 4, No. 7-24085, No. 9-10358, etc.).

However, there is a demand for a multi-piece solid golf ball which is further excellent in flight performance, has good spin characteristics, is excellent in feeling of wood, iron and putter shots, and is also excellent in crispy resistance and durability.

[0004]

MEANS FOR SOLVING THE PROBLEMS AND BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has conducted diligent studies in order to meet the above demands, and as a result, a multi-piece solid golf ball having a solid core covered with two layers of inner and outer covers. In the above, the solid core is formed to be relatively soft, the inner cover layer is formed mainly of a thermoplastic polyester elastomer, and the outer cover layer is formed mainly of a thermoplastic polyurethane elastomer, and the inner cover layer has a Shore D hardness of 28 to 58 and an outer side. It has been found that setting the Shore D hardness of the cover layer to 30 to 55 is effective.

That is, the present invention provides (1) a multi-piece solid golf ball having a solid core and two inner and outer layers covering the solid core, wherein the solid core has a diameter of 30 to 40 mm and a load of 100 kg on the solid core. Deformation amount under load is 2.8 ~
The inner cover layer has a Shore D hardness of 28 to 58 and a thermoplastic polyurethane as a resin material for the outer cover layer. A multi-piece solid golf ball characterized in that the outer cover layer is formed of a resin material having a Shore D hardness of 30 to 55 using only an elastomer, and (2) the moment of inertia of the entire ball is 84 to 90 g · c.
m ² is the golf ball according to (1), (3) the golf ball according to (1) or (2), wherein the outer cover layer contains 30% by weight or less of an inorganic filler, and (4) the inner cover layer is inorganic-filled. The golf ball according to any one of (1) to (3), in which 30% by weight or less of the material is added, (5) the outer cover layer has a specific gravity of 1.05 to 1.4 (1) to (4) (6) The golf ball according to any one of (1) to (5), wherein the inner cover layer has a specific gravity of 1.05 to 1.4. The golf ball according to any one of (1) to (6), which has a specific gravity of 0.9 to 1.2, (8) the outer cover layer has a thickness of 0.5 to 2.5 mm, and the inner cover layer has a thickness of 0.5 to 2.5 mm. The thickness is 0.5 to 3.0 mm, and the thickness of the entire cover is 1.0 to 5.5 mm (1) to (7)
A golf ball according to claim 1.

The golf ball of the present invention has a long flight distance and high controllability on iron shots, and also has a good feel when shot with any of the wood, iron and putter clubs. It has excellent resistance to crisping and has excellent durability when subjected to control shots.

The present invention will be described in more detail below.
The multi-piece solid golf ball of the present invention has a cover having a two-layer structure including a solid core and an inner cover layer and an outer cover layer that cover the solid core.

Here, the solid core is mainly composed of a rubber base material. As the rubber base material, natural rubber and / or synthetic rubber conventionally used for solid golf balls can be used. In the above, 1,4-polybutadiene having a cis structure of at least 40% is particularly preferable. In this case, if desired, natural rubber, polyisoprene rubber, styrene-butadiene rubber or the like may be appropriately mixed with the polybutadiene.

More specifically, the solid core of the golf ball of the present invention can be obtained by adjusting a vulcanization condition, a compounding ratio and the like by a usual method. Usually, the solid core formulation contains a base rubber, a crosslinking agent, a co-crosslinking agent, an inert filler and the like. As the base rubber, the above-mentioned natural rubber and / or
Alternatively, synthetic rubber or the like can be used, and examples of the crosslinking agent include organic peroxides such as dicumyl peroxide and di-t-butyl peroxide, but dicumyl peroxide is particularly preferable. . The compounding amount of the crosslinking agent is usually 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the base rubber.

The co-crosslinking agent is not particularly limited, and examples thereof include metal salts of unsaturated fatty acids, particularly zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms (eg acrylic acid, methacrylic acid, etc.). However, zinc acrylate is particularly preferred. The content of the co-crosslinking agent is 10 to 50 parts by weight, preferably 20 to 48 parts by weight, based on 100 parts by weight of the base rubber.
Parts by weight.

Examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate and zinc carbonate, but zinc oxide and barium sulfate are generally used, and the compounding amount thereof is the specific gravity of the core and the cover and the ball. Although not particularly limited, the amount is usually 1 to 30 parts by weight with respect to 100 parts by weight of the base rubber. In the present invention, the optimum hardness of the solid core can be obtained by appropriately adjusting the compounding ratio of zinc oxide and barium sulfate.

The solid core composition obtained by blending the above components is kneaded using an ordinary kneading machine such as a Banbury mixer or a roll, and then compressed or injection-molded into a core mold to form a molded product with a crosslinking agent and The solid core is heated and cured at a temperature sufficient for the co-crosslinking agent to act (for example, when dicumyl peroxide is used as the cross-linking agent and zinc acrylate is used as the co-crosslinking agent, about 130 to 170 ° C.). Prepare.

The solid core has a deformation amount (deflection amount) of 2.8 to 6.0 mm, preferably 2.9 to 5.0 mm when a load of 100 kg is applied. If the deformation amount under a load of 100 kg is less than 2.8 mm (hard), disadvantages such as a hard hit feeling may occur. If the amount of deformation is too large (too soft), the resilience may deteriorate.

The specific gravity of the solid core is preferably 0.9 to 1.2, more preferably 1.01 to 1.18.

In the present invention, the solid core preferably has a diameter of 30 to 40 mm, particularly 33 to 39 mm. The solid core may have a multi-layer structure as long as it has a deformation amount under the load of 100 kg.

Next, only the thermoplastic polyester elastomer is used as the resin material for the inner cover layer.

In this case, the thermoplastic polyester elastomer is synthesized from terephthalic acid, 1,4-butanediol and polytetramethylene glycol (PTMG) or polypropylene glycol (PPG), and the polybutylene terephthalate (PBT) portion is hard. Segment, polytetramethylene glycol (PTM
G) or a polypropylene ester (PPG) moiety is a polyether ester-based multi-block copolymer having a soft segment, and specifically, Hytrel 4047, G3548W, G4748, H5577.
(Manufactured by Toray DuPont) and the like.

[0018]

Further, the inner cover layer using only the above thermoplastic polyester elastomer as the resin material contains no inorganic filler such as zinc oxide, barium sulfate or titanium dioxide.
It may be contained in an amount of about 30% by weight.

The inner cover layer has a Shore D hardness of 28.
It is necessary that the hardness is in the range of 58 to 58, especially 30 to 56, and if the Shore D hardness is lower than 28, the resilience is impaired. If it is higher than 58, the feel on impact may deteriorate.

Further, the specific gravity of the inner cover layer is 1.05.
It is preferably 1.4, particularly 1.1 to 1.3.

The thickness of the inner cover layer is 0.5 to
It is preferably 3.0 mm, particularly preferably 0.9 to 2.5 mm.

On the other hand, the outer cover layer is made of thermoplastic polyurethane elastomer. Here, the molecular structure of the thermoplastic polyurethane elastomer is composed of a polymer polyol compound forming a soft segment, a monomolecular chain extender forming a hard segment, and diisocyanate.

The high molecular weight polyol compound is not particularly limited, but polyester polyols,
Any of polyether-based polyol, copolyester-based polyol, and polycarbonate-based polyol may be used. Examples of the polyester-based polyol include polycaprolactone glycol, poly (ethylene-1,4-adipate) glycol, poly (butylene-1,4-adipate). ) Glycols and the like, copolyester-based polyols such as poly (diethylene glycol adipate) glycol and the like, polycarbonate-based polyols such as (hexanediol-1,6-carbonate) glycol and the like,
Examples of the polyether polyol include polyoxytetramethylene glycol and the like. Their number average molecular weight is about 600 to 5000, preferably 1000 to 30.
00.

As the diisocyanate, an aliphatic diisocyanate is preferably used in consideration of the yellowing resistance of the cover. Specific examples thereof include hexamethylene diisocyanate (HDI), 2,2,4 (2,4,4) -trimethylhexamethylene diisocyanate (TMDI), lysine diisocyanate (LDI), and particularly H
DI is preferable from the viewpoint of compatibility when blending with other resins.

The monomolecular chain extender is not particularly limited, and usual polyhydric alcohols and amines can be used, and specifically, 1,4-butylene glycol and 1,2-
Ethylene glycol, 1,3-propylene glycol,
1,6-hexylene glycol, 1,3-butylene glycol, dicyclohexylmethylmethanediamine (hydrogenated MDA), isophoronediamine (IPDA) and the like can be mentioned.

The thermoplastic polyurethane elastomer having a tan δ peak temperature measured by viscoelasticity of −15 ° C. or lower, particularly −16 ° C. to −50 ° C. is preferable in terms of softness and resilience.

As such a thermoplastic polyurethane elastomer, commercially available products can be used. For example, Pandex T7298 (-20 ° C) and T7295 (-2).
6 ° C.), the same T7890 (−30 ° C.) (manufactured by Dainippon Ink and Chemicals, Inc.) and the like, in which the diisocyanate is aliphatic. All numbers in parentheses are tan δ
The peak temperature is shown.

[0029]

The outer cover layer, which uses only the thermoplastic polyurethane elastomer as the resin material, contains an inorganic filler such as zinc oxide, barium sulfate or titanium dioxide.
You may contain less than weight%, especially 1 to 25 weight%.

The Shore D hardness of the outer cover layer is from 30 to
55, preferably 32-54, more preferably 33-5
It is 3. If the Shore D hardness is less than 30, the resilience is impaired. If it is higher than 55, the feel on impact may deteriorate.

The specific gravity of the outer cover layer is 1.05 to 1.4,
It is particularly preferably 1.07 to 1.35.

The thickness of the outer cover layer is 0.5 to 2.5.
mm, particularly preferably 0.9 to 2.4 mm,
If it is thinner than 0.5 mm, the durability will be deteriorated, and if it is thicker than 2.5 mm, the resilience and feel will be deteriorated.

In this case, the total thickness of the inner and outer cover layers (thickness of the entire cover) is preferably 1.0 to 5.5 mm, and particularly preferably 1.5 to 5.0 mm.

The inner cover layer and the outer cover layer can be formed by a known method such as injection molding or compression molding using a half shell.

[0036] Such multi-piece solid golf ball thus obtained is, the moment of inertia was measured by the method which will be described later, 83g · cm ² or more, and particularly 84~90g · cm ²
Is preferred. Inertia moment is 83g · cm
^{If it is} less than ² , rolling at the time of putting becomes dull,
There may be a disadvantage of lacking straightness.

Although dimples are formed on the outer cover layer according to a conventional method, the diameter, weight, etc. of the golf ball of the present invention are 42.67 mm in diameter in accordance with the Rules of Golf.
As described above, the weight can be formed to be 45.93 g or less.

[0038]

INDUSTRIAL APPLICABILITY The multi-piece solid golf ball of the present invention has a long flight distance, excellent controllability, a good feel, and excellent durability.

[0039]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples and Comparative Examples Solid cores having the compositions shown in Table 1 were prepared.

[0041]

[Table 1] * Polybutadiene: BR01 manufactured by Japan Synthetic Rubber Co., Ltd.

Next, the core was coated with an inner cover layer having the composition shown in Table 2 by injection molding, and then an outer cover layer having the composition shown in Table 3 by injection molding.
A three-piece golf ball having the weight and outer diameter shown in FIG.

The moment of inertia of the obtained golf ball,
The flight distance, spin rate, feel, crispness resistance, and continuous durability were measured by the following methods. The results are shown in Tables 4 and 5.

[0044]Moment of inertia It was calculated from the following formula. That is, the moment of inertia is
Calculated value from diameter (thickness) and specific gravity.
It can be calculated by the following formula by regarding it as a sphere.
It In this case, the ball is spherical in calculation, but in reality
Since there are dimples in the outer cover layer, the specific gravity of the outer cover layer is
It is smaller than the actual outer cover resin. Here it is
Is called the outer cover virtual specific gravity.
Calculate the M. M = (π / 58880000) × {(r1-r2) × D1
^Five+ (R2-r3) xD2^Five+ R3 x D3^Five} M: Moment of inertia (g · cm² ) r1: Specific gravity of core D1: Core diameter r2: inner cover layer specific gravity D2: inner cover layer diameter (with inner cover layer formed on the core
Diameter of the sphere after r3: Outer cover layer virtual specific gravity D3: Outer cover layer diameter (ball diameter) * The unit of each diameter is mmFlying distance Using a swing robot, the driver (# W1, head
Hit at a speed of 45 m / sec), carry, and tota
The flight distance of each of these was measured.Spin amount # W1 and sand wedge (#SW, head speed 2
0m / sec), the ball was lifted immediately after the impact.
The motions were photographed and calculated by photographic resolution.Feeling Professional golfer about # W1 and putter (#PT)
The feel when hit by three people was evaluated according to the following criteria.
It was ○: Soft △: a little hard ×: HardCrisp resistance With a swing robot, sand wedge (#SW,
The ball speed is 38m / sec)
It was hit and visually evaluated. ○: Good △: Normal ×: inferiorContinuous durability Head speed 38 using flywheel striking M / C
Repeatedly hit at m / sec until the ball is destroyed
It was evaluated by the number of hits. ○: Good ×: bad

[0045]

[Table 2] Hytrel: Toray-Dupont, thermoplastic polyester elastomer PEBAX3533: Atochem, polyamide-based elastomer High Milan: Mitsui-Dupont Polychemical, ionomer resin Surlyn 8120: DuPont, ionomer resin

[0046]

[Table 3] PANDEX T7890 / T7298: Dainippon Ink and Chemicals, Thermoplastic Polyurethane Elastomer Himilan: Mitsui DuPont Polychemical, Ionomer Resin Surlyn 8120: DuPont, Ionomer Resin

[0047]

[Table 4]

[0048]

[Table 5]

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Junji Hayashi, 20 Onohara, Chichibu, Saitama Prefecture, within Bridgestone Sports Co., Ltd. (72) Inventor, Akira Kawada, 20 Onohara, Chichibu City, Saitama, within Bridgestone Sports Co., Ltd. (56) References JP-A-6-343718 (JP, A) JP-A-6-299052 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A63B 37/00

Claims (8)

(57) [Claims] 1. A solid core and inner and outer surfaces 2 for covering the solid core
In a multi-piece solid golf ball having a layer cover, the solid core has a diameter of 30 to 40 mm,
The amount of deformation of the solid core under a load of 100 kg is 2.
8 to 6.0 mm, only the thermoplastic polyester elastomer is used as the resin material for the inner cover layer, the Shore D hardness of the inner cover layer is 28 to 58, and the resin material for the outer cover layer is A multi-piece solid golf ball, wherein only the plastic polyurethane elastomer is used, and the resin material of the outer cover layer is formed to have a Shore D hardness of 30 to 55. 2. The moment of inertia of the entire ball is 84-9.
The golf ball according to claim 1, which has a weight of 0 g · cm ² . 3. The outer cover layer contains 30% by weight of an inorganic filler.
The golf ball according to claim 1, which is added below. 4. The inner cover layer contains 30% by weight of an inorganic filler.
The golf ball according to claim 1, wherein the golf ball is added below. 5. The outer cover layer has a specific gravity of 1.05 to 1.4.
The golf ball according to claim 1, wherein the golf ball is a golf ball. 6. The specific gravity of the inner cover layer is 1.05 to 1.4.
The golf ball according to claim 1, wherein the golf ball is a golf ball. 7. The golf ball according to claim 1, wherein the specific gravity of the core is 0.9 to 1.2. 8. The outer cover layer has a thickness of 0.5 to 2.5 m.
m, the thickness of the inner cover layer is 0.5 to 3.0 mm,
The thickness of the entire cover is 1.0 to 5.5 mm.
The golf ball according to any one of 1 to 7.