Multi-piece solid golf ball

Abstract

A multi-piece solid golf ball includes a solid core, at least one intermediate layer, and a cover having at least one cover layer. The solid core has a compression deflection of 3.0 mm or more, the intermediate layer is mainly made from a thermoplastic resin and has a shore d hardness of 45 to 55 and a specific gravity of 1.2 or less, and the cover has a shore d hardness of 60 or more and a thickness of 1.6 to 2.3 mm. The golf ball further comprises a ratio of the compression deflection of a sphere composed of the solid core covered with the intermediate layer to the compression deflection of the solid core is more than 0.900 and less than 0.970; and a difference in jis-C hardness between the surface and the center of the solid core is equal to or less than 5.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a multi-piece solid golf ball having at least three layers, more specifically, a solid core, at least intermediate layer, and a cover having at least one cover layer, and particularly to a multi-piece solid golf ball which is capable of giving a player a desirable soft feeling of hitting the golf ball upon putter shot or approach shot and also a desirable feeling of hitting the golf ball upon driver shot, and which is capable of improving the flying performance of the golf ball.

Solid golf balls have been variously improved. For example, an attempt has been made to soften the hardness of a cover of a two-piece golf ball for giving a player a desirable feeling of hitting the golf ball.

In the case of the above two-piece golf ball, however, if the hardness of the cover is softened, there arises a new problem that the flying distance of the golf ball is shortened.

On the other hand, it has been known that the flying performance of a golf ball can be improved by increasing the hardness of a cover of the golf ball; however, in this case, there arises another problem that the player's feeling of hitting the golf ball upon putter shot or approach shot is degraded.

In this way, it has been difficult to obtain a solid golf ball capable of giving a player a desirable feeling of hitting the golf ball as well as improving the flying performance of the golf ball.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a multi-piece solid golf ball which is capable of giving a player a desirable feeling of hitting the golf ball upon putter shot or approach shot and also a desirable feeling of hitting the golf ball upon driver shot, and which is capable of improving the flying performance of the golf ball.

To achieve the above object, the present inventor has made studies on a multi-piece solid golf ball including at least one intermediate layer between a solid core and a cover.

Eventually, the present inventor has found that a multi-piece solid golf ball characterized in that the solid core has a compression deflection of 3.0 mm or more when a load range of initial 10 kgf to final 130 kgf is applied, the intermediate layer is mainly made from a thermoplastic resin and has a Shore D hardness (ASTM D-2240-75) of 45 to 55 and a specific gravity of 1.2 or less, and the cover has a Shore D hardness of 60 or more and a thickness of 1.6 to 2.3 mm; a ratio of the compression deflection of a sphere composed of the intermediate layer and the solid core covered therewith to the compression deflection of the solid core is more than 0.900 and less than 0.970 [0.900<(compression deflection of sphere/compression deflection of solid core)<0.970]; and a difference in JIS-C hardness (specified under JIS K6301-1996) between the surface and the center of the solid core is equal to or 4 and 6 5 and 7 and 8 is poor in flying performance, and the sample in Comparative Example 5 6 is good in flying performance, and player's feeling upon each of driver shot and putter shot, but is poor in durability against cracks. On the contrary, each of the samples in Examples 1 to 4 is good in flying performance, player's feeling upon each of driver shot and putter shot, and durability against cracks. Further, the sample in each of Examples 1 to 4 is smaller in spin property than that of each of Comparative Examples 1 to 5 and 7 and 8.

While the preferred embodiments of the present invention have been described using the specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit and scope of the following claims.

	TABLE 1
	Example	Comparative Example
	1	2	3	4	1	2	3	4	5	6	7	8
Component for Core	Polybutadiene	100	100	100	100	100	100	100	100	100	100	100	100
(parts by weight)	Zinc Acrylate	25	27.4	24.4	25	28.7	31.6	26.8	27.6	27.6	25	28.7	27.4
	Peroxide (*)	1.2	1.2	1.2	1.2	1.2	1.2	1.2	1.2	1.2	1.2	1.2	1.2
	Anti-aging Agent	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
	Barium Sulfate	25.2	24.2	25.4	18.8	18.9	17.7	29.1	24.1	23.7	19.9	23.8	13.7
	Zinc Oxide	5	5	5	5	5	5	5	5	5	5	5	5
	Zinc Salt of	0.2	0.2	0.2	0.2	0.1	0.1	0.2	0.2	0.2	0.2	0.2	0.2
	Pentachlorothiophenol
Vulcanizing	Primary	Temperature	155	155	155	155	155	155	155	155	155	155	155	155
Condition	Vulcanization	(° C.)
		Time	15	15	15	15	15	15	15	15	30	15	15	15
		(Minute)
	Secondary	Temperature									170
	Vulcanization	(° C.)
		Time									10
		(Minute)
Hardness	A: Core Surface	73	78	71	74	79	82	77	78	71	73	79	78
	(JIS-C)
	B: Core Center	61	64	61	60	65	68	63	64	68	61	65	64
	(JIS-C)
	A-B	12	14	10	14	14	14	14	14	3	12	14	14
	(JIS-C)
(*) mixture of Percumyl D (NOF CORPORATION) and Perhexa 3M-40 (NOF CORPORATION) at weight ratio of 1:1

	TABLE 2
	{circle around (1)}	{circle around (2)}	{circle around (3)}	{circle around (4)}	{circle around (5)}	{circle around (6)}	{circle around (7)}
Component for	Himilan 1706	50	25
Intermediate	Himilan 1650						50
Layer/Cover	Himilan 1557					50
(parts by	Himilan 1605	50	25
weight)	Himilan 1601					50
	Surlyn 8120						50
	Hytrel 4767			100
	Hytrel 4047				100
	Hytrel 3078		50
	Pelprene P150B							50
	Pelprene P150M							50
	Titanium Dioxide	5.6	0	0	0	5.6	5.6	0
Physical	Specific Gravity	0.985	1.020	1.165	1.33	0.965	0.985	1.210
Property	Resin Hardness	63	51	52	43	60	55	54
	(Shore D)

	TABLE 3
	Example	Comparative Example
	1	2	3	4	1	2	3	4	5	6	7	8
Core	Weight (g)	28.71	27.55	27.64	27.82	27.03	27.03	28.2	27.55	27.55	29.54	26.45	26.24
	Compression	4.20	3.75	4.32	4.19	3.49	2.94	3.85	3.75	3.70	4.20	3.50	3.75
	Deflection
	(mm)
Inter-	Kind	{circle around (2)}	{circle around (2)}	{circle around (2)}	{circle around (3)}	{circle around (4)}	{circle around (4)}	{circle around (5)}	{circle around (2)}	{circle around (3)}	{circle around (2)}	{circle around (2)}	{circle around (7)}
mediate	Weight (g)	34.97	34.63	34.65	35.18	35.15	35.15	35.15	34.63	34.65	37.41	32.75	34.63
Layer	Compression	4.01	3.47	3.93	3.95	3.18	2.05	3.30	3.47	3.40	4.00	3.32	3.39
	Deflection
	(mm) (*)
	Gage (mm)	1.42	1.63	1.62	1.46	1.68	1.68	1.68	1.63	1.63	1.70	1.50	1.63
Cover	Type	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (6)}	{circle around (1)}	{circle around (1)}	{circle around (1)}	{circle around (1)}
	Thickness	2.10	2.14	2.13	2.07	2.07	2.07	2.07	2.14	2.13	1.50	2.40	2.14
	(mm)
Ratio of	Intermediate	0.955	0.925	0.910	0.943	0.911	1.003	0.857	0.925	0.919	0.952	0.949	0.904
Compres-	Layer (*)/
sion
Deflec-
tion
Ball	Weight (g)	45.21	45.08	45.07	45.25	45.27	45.27	45.30	45.08	45.30	45.30	45.30	45.30
	Outside	42.70	42.70	42.70	42.70	42.70	42.70	42.70	42.70	42.70	42.70	42.70	42.70
	Diameter
	(mm)
	Compression	3.03	2.72	3.03	3.04	2.73	2.60	2.75	2.82	2.79	3.12	2.65	2.65
	Deflection
	(mm)
Driver	Carry (m)	141.8	141.8	142.5	142.1	142.2	142.0	140.5	138.4	141.4	141.8	141.5	140.8
#W1	Total (m)	155.7	156.2	155.1	155.9	153.6	152.5	152.1	149.5	152.9	155.3	153.8	153.9
(HS35)	Flying	◯	◯	◯	◯	X	X	X	X	X	◯	X	X
	Performance
	Spin (rpm)	3428	3562	2458	3366	3743	3798	3565	3722	3717	3479	3762	3605
	Feeling	◯	◯	◯	◯	◯	Δ	Δ	◯	◯	◯	Δ	◯
Putter	Feeling	◯	◯	◯	◯	◯	◯	X	◯	◯	◯	X	◯
Durability Against	◯	◯	◯	◯	◯	◯	◯	◯	◯	X	◯	◯
Cracks
(*) compression deflection of sphere composed of intermediate layer and core covered therewith

Claims

1. A multi-piece solid golf ball comprising: a solid core; at least one intermediate layer for covering said solid core; and a cover having at least one cover layer for covering said intermediate layer;

wherein said solid core has a comparison deflection of 3.0 mm or more when a load range of initial 10 kgf to final 130 kgf is applied, said intermediate layer is mainly made from a thermoplastic resin and has a shore d hardness of 45 to 55 and a specific gravity of 1.2 or less and less than a specific gravity of said solid core, and said cover has a shore d hardness of 60 or more and a thickness of 1.6 to 2.3 mm;

a ratio of the compression deflection of a sphere composed of said intermediate layer and said solid core covered therewith to the compression deflection of said solid core is more than 0.900 and less than 0.970 [0.900<(compression deflection of sphere/compression deflection of solid core)<0.970]; and

a difference in jis-C hardness (specified under jis K6301-1996) between the surface and the center of said solid core is equal to or less greater than 5 [5≦(surface hardness-center hardness)].

2. A multi-piece solid golf ball according to claim 1, wherein the gage of said intermediate layer is equal to or less than 2.0 mm.

3. A multi-piece solid golf ball according to claim 1, wherein said difference in jis-C hardness between the surface and the center of said solid core is equal to or less than 22.

4. A multi-piece solid golf ball according to claim 1, wherein said ratio of the compression deflection of said sphere composed of said intermediate layer and said solid core covered therewith to the compression deflection of the solid core is more than 0.910 and less than 0.960.

5. A multi-piece solid golf ball comprising: a solid core; at least one intermediate layer for covering said solid core; and a cover having at least one cover layer for covering said intermediate layer;

wherein said solid core has a compression deflection of 3.0 mm or more when a load range of initial 10 kgf to final 130 kgf is applied, said intermediate layer is mainly made from a thermoplastic resin and has a shore d hardness of 45 to 55 and a specific gravity of 1.2 or less and less than a specific gravity of said solid core, and said cover has a shore d hardness of 60 or more;

a ratio of the compression deflection of a sphere composed of said intermediate layer and said solid core covered therewith to the compression deflection of said solid core is more than 0.900 and less than 0.970; and

a difference in jis-C hardness (specified under jis K6301-1996) between the surface and the center of said solid core is equal to or greater than 5 [5≦(surface hardness-center hardness)].