JP3505922B2 - Three 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 three-piece solid golf ball having a three-layer structure of a solid core, an intermediate layer and a cover. More specifically, the hardness distribution of the core and the core, the intermediate layer and the cover are included. The present invention relates to a three-piece solid golf ball which has an excellent flight performance and durability, a good feel at impact and controllability, and an all-round performance by optimizing the hardness distribution of the entire ball.

[0002]

2. Description of the Related Art Golf balls having various structures have hitherto been on the market, and in particular, a two-piece solid golf ball having a rubber-based core covered with a cover made of an ionomer resin or the like. Ball and
Most of the market is a thread-wound golf ball in which a thread-wound core having a thread rubber wound around a solid or liquid center is covered with a cover.

The above two-piece solid golf ball is
Since it has excellent flight performance and durability, it is used by many general golfers, but it has a drawback that it feels very hard to hit and that the control performance is inferior due to the speed at which the ball separates when hit. Therefore, many professional golfers and advanced players use the wound golf ball rather than the two-piece solid golf ball. On the other hand, the thread-wound golf ball has excellent feel and controllability, but has a drawback that it is inferior to the two-piece solid golf ball in terms of flight distance and durability.

As described above, the two-piece solid golf ball and the thread-wound golf ball have mutually contradictory performances, and the player currently selects the golf ball to be used according to his skill and preference. .

Currently, in order to realize a feeling close to that of a thread-wound golf ball in a solid golf ball,
Various soft type two-piece solid golf balls have been proposed. In order to obtain such a soft type two-piece solid golf ball, a soft core is used, but when the core is softened, the resilience is reduced and the flight performance is deteriorated, and the durability is also significantly reduced. Not only may the excellent flight performance and durability characteristic of a two-piece solid golf ball not be obtained, but it may become difficult to withstand actual use. That is, in the conventional two-piece solid golf ball, the structure is determined by which of the four characteristics of softness, resilience, spin characteristics and durability is emphasized, and it is intended to improve any performance. If so, other performance will be deteriorated.

Further, as a matter of course, controllability is also required during a full shot with a wood or a long iron of a driver or the like, and an emphasis is placed on the purpose of improving spin characteristics on a control shot with an approach shot with a short iron or the like. Too much, if a soft cover is used, the spin amount will increase too much when hit by a driver or the like, which is a large deformation area, and the ball will blow up too much (up) and the flight distance will decrease. On the other hand, if the spin amount becomes too small, the ball will drop when it falls, and it will fall too early, which will also adversely affect the flight distance, and eventually a proper spin amount is required even when hit by the driver. Becomes

The present invention has been made in view of the above circumstances. The hardness distribution of the core is optimized, and further, the core, the intermediate layer,
Further, by optimizing the hardness distribution of the entire ball including the cover, it is an object of the present invention to provide a golf ball which can simultaneously satisfy good flight performance and durability and good hit feeling and controllability.

[0008]

DISCLOSURE OF THE INVENTION Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the three-piece structure has a three-layer structure including a solid core, an intermediate layer and a cover. Optimum in solid golf balls by making the core surface hardness higher than the core center hardness to optimize the hardness distribution of the core, the intermediate layer hardness higher than the core surface hardness, and the cover hardness higher than the intermediate layer hardness. It has been found that a golf ball having a hardness distribution of 3 can be obtained, and a solid golf ball having all-round performance having excellent flight performance and durability and good controllability can be obtained.

That is, in a three-piece solid golf ball having a three-layer structure of a solid core, an intermediate layer, and a cover, the center hardness of the core is 75 degrees or less and the core surface hardness is 85, as measured by a JIS-C type hardness meter. The core surface hardness is formed 5 to 25 degrees higher than the core center hardness, the intermediate layer hardness is formed higher than the core surface hardness in the range of less than 10 degrees, and the cover hardness is formed higher than the intermediate layer hardness. As a result, (i) a core having an optimum hardness distribution can be formed, and when the ball is deformed at the time of impact, the core surface formed harder than the center of the core effectively prevents excessive deformation of the core, and the strain energy is efficiently used. It can be easily replaced with repulsive energy, the flight distance increases, and a soft and good feel can be obtained due to the soft core center. , (Ii) By covering the softly formed core with a harder intermediate layer and a cover that is harder than this intermediate layer, the entire ball has an optimal hardness distribution and energy loss due to excessive deformation at impact is minimized. It was found that a golf ball having an effective rebound can be obtained. Furthermore, in a three-piece solid golf ball having such a hardness distribution,
(Iii) The intermediate layer and the cover are made of ionomer resin 10
By forming a thermoplastic resin containing 100% by weight to 100% by weight as a main material, the intermediate layer and the cover can be firmly adhered, and the durability can be improved in combination with the hard formed cover. It is a finding.

The inventors of the present invention set the hardness distribution of the three-piece solid golf ball as described above, thereby optimizing the spin amount at the time of a full shot with a driver, etc., by the above-mentioned effects (1) to (3). The present invention has been completed by finding that a golf ball excellent in durability and feel at the same time can be obtained.

Accordingly, the present invention provides the following golf balls. Claim 1: In a three-piece solid golf ball having a three-layer structure of a solid core, an intermediate layer and a cover, the solid core is made of an elastomer containing cis-1,4-polybutadiene as a main component, and the core has a diameter of 34 to 41 mm. In addition, the center hardness of the core is 50 to 75 degrees, the core surface hardness is 60 to 83 degrees, and the intermediate value is measured by a JIS-C type hardness meter.
The layer hardness is 63 to 85 degrees, the cover hardness is 70 to 95 degrees , the core surface hardness is 5 to 25 degrees higher than the core center hardness, and the intermediate layer hardness is less than 10 degrees from the core surface hardness. A three-piece solid golf ball, which is high and has a cover hardness higher than that of the mid layer. Claim 2: The surface hardness of the core is 62-as measured by a JIS-C type hardness meter.
The three-piece solid golf ball of claim 1, wherein the angle is 83 degrees.
Fuball. Claim 3: Cover hardness of 70 to 9 as measured by JIS-C type hardness tester.
The three-piece solid according to claim 1 or 2, which is twice.
Golf ball. Claim 4: The intermediate layer is mainly composed of a thermoplastic resin, and the heat
The plastic resin contains 10 to 100% by weight of the ionomer resin.
A three-piece solid golf ball according to claim 1, 2, or 3 . Claim 5: The intermediate layer has a thickness of 0.2 to 3 mm and a specific gravity of 0.9 or more.
The three-piece solid golf ball according to claim 1 , wherein the three-piece solid golf ball is less than 2. Claim 6: The cover is mainly made of a thermoplastic resin, and the heat
The plastic resin contains 10 to 100% by weight of the ionomer resin.
A three-piece solid golf ball according to any one of claims 1 to 5 . Claim 7: The cover has a thickness of 0.2 to 3 mm and a specific gravity of 0.9 or more.
The three-piece solid golf ball according to any one of claims 1 to 6, which has a number of less than 2. [8] The three-piece solid golf ball of any one of [1] to [7], wherein the total thickness of the intermediate layer and the cover is 2 mm or more. Claim 9: The solid core gradually increases from the core surface toward the core center.
It is formed to be soft, and the intermediate layer hardness is the core surface hardness.
From 1 degree to less than 10 degrees as measured by JIS-C type hardness tester
Is higher in the range of, and the cover hardness is JIS than the intermediate layer hardness.
-High in the range of 1 degree or more and less than 15 degrees as measured by a C-type hardness tester.
Moreover, the total thickness of the intermediate layer and the cover is 2 to 5.5 m.
The three according to any one of claims 1 to 8, which is m.
Peace solid golf ball. Claim 10: intermediate layer having a high hardness in the range of 1-8 degrees above the core surface hardness 請
The three-piece solid golf ball according to any one of claims 1 to 9 . Claim 11: 請 cover hardness is high in the range of 1 to 13 degrees from the intermediate layer hardness
The three-piece solid golf ball according to any one of claims 1 to 10 .

The present invention will be described in more detail below. The three-piece solid golf ball 1 of the present invention comprises:
As shown in FIG. 1, the solid core 2 has an optimized hardness distribution, an intermediate layer 3 harder than the surface of the core 2, and a cover 4 harder than the intermediate layer 3.

In the golf ball 1 of the present invention, the hardness distribution of the solid core 2 is first optimized. That is, the central hardness of the core 2 is measured with a JIS-C type hardness meter (hereinafter referred to as JIS-
C hardness), 75 degrees or less, preferably 50 to 70
And more preferably 51 to 68 degrees. The surface hardness of the core 2 is 85 degrees or less, preferably 60 to 85.
And more preferably 62 to 83 degrees. When the central hardness exceeds 75 degrees and the surface hardness exceeds 85 degrees, the feel on impact becomes hard, which is contrary to the gist of the present invention. On the other hand, if the core is too soft, the deformation at the time of hitting becomes large, and the flight distance and durability are reduced due to energy loss.

The surface hardness of the core is 5 rather than the central hardness.
It is formed to be -25 degrees, preferably 7 to 22 degrees. When the difference in hardness is less than 5 degrees, the core surface hardness and the center hardness are almost the same, the hardness distribution disappears, the surface becomes flat, and the feel on impact becomes hard. On the other hand, if it exceeds 25 degrees, the core center hardness becomes too low and sufficient resilience cannot be obtained. By providing a hardness distribution that provides a hardness difference between the surface of the core and the center in this way, the surface formed harder than the center during ball deformation at impact effectively prevents excessive deformation of the core and reduces strain energy. The repulsive energy can be efficiently replaced. Further, a good feeling can be obtained by the core portion which is softer than the core surface.

The hardness distribution of the solid core is not limited as long as the core surface is formed to be hard within the range of 5 to 25 degrees from the center of the core, as described above. In particular, the solid core gradually becomes softer from the core surface toward the center. The formation is preferable from the viewpoint of efficient energy transmission.

The diameter of the solid core is 34-4.
It is preferably 1 mm, particularly 34 to 39 mm, and the hardness, weight, specific gravity and the like of the entire core are not particularly limited and can be appropriately adjusted within a range that can achieve the object of the present invention. The hardness is 2.3 to 5.5 mm, especially 2.5 to 4.8 mm, when the amount of deformation is 100 kg.
The weight can be 25 to 42 g, especially 27 to 41 g.

In the present invention, the core composition for forming the solid core is not particularly limited, and includes base rubbers, crosslinking agents, co-crosslinking agents, inert fillers and the like, which are usually used for forming the solid core. It can be formed by using. In this case, natural rubber and / or synthetic rubber conventionally used for solid golf balls can be used as the base rubber, but in the present invention, 1,4-having a cis structure of at least 40% or more is used. Cis-polybutadiene is particularly preferred. In this case, if desired, natural rubber, polyisoprene rubber, styrene-butadiene rubber or the like may be appropriately mixed with the polybutadiene. Further, as a cross-linking agent, dicumyl peroxide, di-t-butyl peroxide, 1,1-bis (t-butylperoxy) 3,3,3
Examples thereof include organic peroxides such as 5-trimethylcyclohexane, but dicumyl peroxide and 1,1-bis (t-butylperoxy) 3,3,5 are particularly preferable.
A blend of trimethylcyclohexane. In this case, in order to form the solid core having the above hardness distribution, dicumyl peroxide and 1,1 are used as the crosslinking agent.
-Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane was used by blending, and at 20 ° C at 20 ° C.
It is preferable to adopt a method of vulcanizing for minutes,
The difference between the core center hardness and the surface hardness can be changed by appropriately changing the vulcanization temperature and the vulcanization time.

The co-crosslinking agent is not particularly limited,
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 (for example, acrylic acid, methacrylic acid, etc.), and zinc acrylate is particularly preferable. The amount of the cross-linking agent is appropriately set and is usually 7 to 4 with respect to 100 parts by weight of the base rubber component.
It is about 5 parts by weight. Further, examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate and the like, 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, it is usually 40 parts by weight or less with respect to 100 parts by weight of the base rubber.
In the present invention, the hardness and weight of the entire core can be adjusted to optimum values by appropriately adjusting the blending ratio of the crosslinking agent and the filler such as zinc oxide and barium sulfate.

The core composition obtained by blending the above-mentioned components is kneaded using an ordinary kneading machine such as a Banbury mixer or a roll, and is compressed or injection-molded with a core mold, and the molded body is subjected to the above-mentioned temperature. The solid core of the present invention having an optimum hardness distribution can be prepared by heat curing under the conditions.

The intermediate layer 3 covering the core 2 is JIS-C.
The hardness is 85 degrees or less, preferably 55 to 85 degrees, and more preferably 63 to 85 degrees. In this case, the intermediate layer hardness is formed higher than the core surface hardness in the range of less than 10 degrees,
It is preferably formed 1 to 8 degrees higher. If the hardness difference is 10 degrees or more, sufficient resilience cannot be obtained. By forming the intermediate layer hardness higher than the core surface hardness in this way, the resilience of the core can be maintained.

The thickness, specific gravity, etc. of the intermediate layer can be appropriately adjusted within the range where the object of the present invention can be achieved. The thickness is 0.2 to 3 mm, particularly 1 to 2.5 mm, and the specific gravity is 0.9
It is preferably not less than 1.2 and particularly preferably 0.92 to 1.18.

The intermediate layer 3 is for compensating for the decrease in the resilience of the softly formed solid core, and is made of a material having excellent resilience within the above-mentioned hardness range. 1601, 1605, 185
Ionomer resins such as 5,1856,1706 (manufactured by Mitsui-DuPont Polychemical Co., Ltd.) and Surlyn 8120,7930 (manufactured by DuPont) are preferably used. In this case, it is preferable to use a thermoplastic resin containing 10 to 100% by weight, particularly 30 to 100% by weight, of the ionomer resin for the intermediate layer.

Further, as the thermoplastic resin other than the above-mentioned ionomer resin constituting the intermediate layer, a maleic anhydride-modified product of ethylene-unsaturated alkyl carboxylate (H
PRAR201 (Mitsui DuPont Polychemical Co., Ltd.)
Etc.), ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid alkyl ester terpolymer (Nucrel A)
N4307, AN4311 (manufactured by Mitsui-DuPont Polychemical Co., Ltd.), polyester elastomer (Hytrel 4047 (manufactured by Toray-Dupont), etc.), polyamide elastomer (PEBAX3533 (manufactured by Atochem))
Etc.) and a thermoplastic elastomer having a crystalline polyethylene block (Dyalon 6100P, HSB60).
4, same 4600P (above, Japan Synthetic Rubber Co., Ltd.) etc.)
Etc., and these may be used alone or in combination of two or more, and the blending amount thereof is 0 of the whole intermediate layer composition.
The amount can be ˜90 wt%, preferably 0 to 70 wt%, and more preferably 5 to 70 wt%.

Among the above thermoplastic resins, the thermoplastic elastomer having a crystalline polyethylene block has a molecular structure of E-EB system, E-EB-E system, E-EB-S system (where E is a polyethylene crystal block). , EB is a relatively random copolymer structure composed of ethylene and butylene, and S is a polystyrene crystal block).
This thermoplastic elastomer can be obtained by hydrogenating polybutadiene or a styrene-butadiene copolymer. Incidentally, in this intermediate layer, in addition to the thermoplastic resin containing the above ionomer resin or the like, an inorganic filler such as zinc oxide or barium sulfate as a weight adjusting agent, or an additive such as titanium dioxide for coloring may be added. it can.

The cover 4 covering the intermediate layer 3 needs to have a higher hardness than the intermediate layer, and the cover hardness is JIS-C hardness of 95 degrees or less, preferably 60 to 9.
It is formed at 3 degrees, more preferably at 70 to 92 degrees. When the JIS-C hardness of the cover exceeds 95 degrees, the difference in hardness between the intermediate layer and the cover becomes large, and the durability may be lowered and the feel may be hard. In this case, the cover hardness is preferably less than 15 degrees, more preferably 1 to 13 degrees higher than the intermediate layer hardness. If the hardness difference is 15 degrees or more, the durability may decrease and the feel may be hard.

The thickness, specific gravity, etc. of the cover can be appropriately adjusted within the range in which the object of the present invention can be achieved. The thickness is 0.2 to 3 mm, particularly 1 to 2.5 mm, and the specific gravity is 0. .9
It is preferably not less than 1.2 and particularly preferably 0.92 to 1.18. The total thickness of the intermediate layer and the cover is 2
It is preferably at least mm, and particularly preferably 2.5 to 5.5 mm. If the thickness is less than 2 mm, the impact durability may decrease.

The cover composition is not particularly limited,
It can be formed of a known material having a suitable performance as a cover material for a golf ball, for example, an ionomer resin, a polyester elastomer, a polyamide elastomer or the like alone, or a urethane resin in these resins,
A resin mixture obtained by mixing an ethylene-vinyl acetate copolymer and the like can be used, but an ionomer resin is particularly preferable, and two or more kinds of ionomer resins can be used in combination. In this case, the ionomer resin is 10 to 1
It is preferable to form the cover by using a thermoplastic resin as a main material in an amount of 00% by weight, particularly 50 to 100% by weight.

Further, a UV absorber, an antioxidant, a dispersion aid such as metal soap and the like may be added to the cover composition as needed. The method for covering the cover is not particularly limited, and usually, the core is wrapped with two covers formed in advance in a hemispherical shape and heat-pressed, or the composition for a cover is injection-molded to wrap the core. Good.

Here, although not particularly limited in the present invention, both the intermediate layer 3 and the cover 4 are formed of a material mainly containing a thermoplastic resin containing 10 to 100% by weight of an ionomer resin. It is preferable that the intermediate layer and the cover can be more firmly adhered to each other, and the durability can be further improved in combination with the hard-formed cover. In this case, the mixing ratio of the ionomer resin may be different between the mid layer 3 and the cover 4.

The golf ball thus obtained is
Dimples can be formed on the surface of the cover according to a conventional method, and after the formation, buffing is performed on the surface,
It is possible to complete the work such as painting and stamping.

The three-piece solid golf ball of the present invention has the above constitution, but the hardness of the entire ball is 10
The amount of deformation when a load of 0 kg is applied is preferably 2.3 to 4.3 mm, particularly preferably 2.5 to 4 mm. The ball properties such as ball weight and diameter can be appropriately set according to the golf rules.

[0032]

EFFECTS OF THE INVENTION The three-piece solid golf ball of the present invention has good flight performance and durability and a soft and good shot feeling, and in particular, the spin amount at the time of a full shot with a driver or the like is optimized and the flight performance and The feel is improved.

[0033]

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. The amounts of the components of the core, intermediate layer and cover in Tables 1 and 2 are all parts by weight.

[Examples and Comparative Examples] Rubber compositions having the compounding compositions shown in Table 1 were kneaded and vulcanized and molded in the mold under the vulcanization conditions shown in Table 1. Solid cores 1 to 13 were created. According to JIS-
The C hardness and diameter were measured, and the results are shown in Tables 3 and 4. The JIS-C hardness of the core was obtained by cutting the core in half and measuring the hardness (center hardness) of the center and the hardness (surface hardness) of the core surface (spherical surface) (measurement values are average values of 5 points). is there).

[0035]

[Table 1]

Next, the intermediate layer and the cover composition shown in Table 2 were kneaded, and the solid core and the intermediate layer were coated by injection molding to obtain the three-piece solid golf balls shown in Tables 3 and 4. At this time, the JIS-C hardness, the specific gravity and the thickness of the intermediate layer and the cover were measured every time the intermediate layer and the cover were molded. The results are also shown in Tables 3 and 4.

[0037]

[Table 2] * 2: Ionomer resin manufactured by Mitsui-DuPont Polychemical Co., Ltd. * 3: Ionomer resin manufactured by DuPont, USA * 4: Maleic anhydride modified product of ethylene-ethyl acrylate copolymer manufactured by Mitsui-DuPont Polychemical Co., Ltd. * 5 : Tertiary copolymer of ethylene / methacrylic acid / acrylic acid ester manufactured by Mitsui / DuPont Polychemical * 6: Polyester elastomer manufactured by Toray DuPont * 7: Polyamide elastomer manufactured by Atochem * 8: Japan synthetic rubber ( Co., Ltd. block copolymer polybutadiene hydrogenated product E-EB-E system * 9: Same as * 1 in Table 1

For each golf ball obtained, the ball hardness, flight performance, spin characteristics, feel at impact,
And the durability were evaluated. The results are also shown in Tables 3 and 4. The amount of deformation (mm) of the ball when a ball hardness of 100 kg was applied was measured. Flying performance A striking machine made by True Temper Co. is used, and a club is a driver (# W1) with a head speed of 45 m / sec (HS45) and 35 m.
/ Sec (HS35) spins when hit,
Carry, total distance was measured.

The club used is HS45.
In the case of "PRO 230 TITAN" (manufactured by Bridgestone Sports Co., Ltd.), 11 degree loft, Shaft Harmotech Light HM50J (HK), hardness S, balance D
2, HS35 "ESSERIO" (manufactured by Bridgestone Sports Co., Ltd.), loft 14 degrees, shaft hardness R
Was used. Hit feeling Head speed 45m / sec (HS45) and 35m /
Five players of sec (HS35) actually hit the ball and judged according to the following criteria. ◯: Soft Δ: Normal ×: Hard durability A comprehensive evaluation was performed by combining continuous impact durability and cut durability, and judged according to the following criteria. ○: Very good △: Normal ×: Inferior

[0040]

[Table 3]

[0041]

[Table 4]

From the results of Tables 3 and 4, Comparative Examples 1 and 7 have a small difference between the core surface hardness and the core center hardness, and the hardness distribution of the core is not optimized, and Comparative Example 7 has an intermediate core surface. It is harder than the layers. In Comparative Examples 2, 5 and 6, the core surface is harder than or the same as that of the intermediate layer. In Comparative Example 3, the intermediate layer is harder than the core surface. Comparative Example 4 is a two-piece solid golf ball. Furthermore, in Comparative Example 5, the center and the surface hardness of the core are hard. Due to these factors, the golf balls of Comparative Examples 1 to 7 are not fully satisfied with respect to any or all of the flight distance, feel at impact, durability, and appropriate spin amount, or the golf balls are considerably inferior in full shot with a driver. .

On the other hand, the golf balls of the present invention (Examples 1 to 7) have an appropriate spin amount on a full shot with a driver to increase the flight distance and are excellent in both shot feel and durability. I was able to confirm.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a three-piece solid golf ball of the present invention.

[Explanation of symbols]

1 golf ball 2 solid core 3 Middle class 4 cover

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-24084 (JP, A) JP-A-6-23069 (JP, A) JP-B-63-61029 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) A63B 37/00

Claims (11)

(57) [Claims] 1. A three-piece solid golf ball having a three-layer structure including a solid core, an intermediate layer and a cover, wherein the solid core is made of an elastomer containing cis-1,4-polybutadiene as a main component, and the core has a diameter of 34 to 34.
In addition to being 41 mm, the core hardness is 50 to 75 degrees and the core surface hardness is 6 as measured by a JIS-C type hardness meter.
0-83 degrees, intermediate layer hardness 63-85 degrees, cover hardness
70 to 95 degrees , the core surface hardness is 5 to 25 degrees higher than the core center hardness, the intermediate layer hardness is higher than the core surface hardness less than 10 degrees, and the cover hardness is higher than the intermediate layer hardness. A three-piece solid golf ball characterized in that 2. The core surface is measured by a JIS-C type hardness tester.
The sleepy according to claim 1, wherein the surface hardness is 62 to 83 degrees.
Susolid Golf Ball. 3. The cover is measured by a JIS-C type hardness tester.
The three according to claim 1 or 2, which has a hardness of 70 to 92 degrees.
Peace solid golf ball. 4. The intermediate layer is mainly composed of a thermoplastic resin.
And the thermoplastic resin contains an ionomer resin in an amount of 10 to 10.
The three-piece solid golf ball according to claim 1, 2 or 3, containing 100% by weight . 5. The intermediate layer according to claim 1, wherein the intermediate layer has a thickness of 0.2 to 3 mm and a specific gravity of 0.9 or more and less than 1.2 .
The three-piece solid golf ball of item 1 . 6. The cover is mainly made of a thermoplastic resin.
And the thermoplastic resin contains an ionomer resin in an amount of 10 to 10.
The three-piece solid golf ball according to claim 1 , wherein the three-piece solid golf ball contains 100% by weight . 7. The cover according to claim 1, wherein the cover has a thickness of 0.2 to 3 mm and a specific gravity of 0.9 or more and less than 1.2 .
The three-piece solid golf ball of item 1 . 8. The three-piece solid golf ball according to any one of claims 1 to 7 the total thickness of a combination of the intermediate layer and the cover is 2mm or more. 9. A solid core comprises a core surface and a core center.
It is formed so that it gradually softens toward
The degree is 1 degree from the core surface hardness measured by JIS-C type hardness tester.
High in the range of 10 degrees or more and less than 10 degrees, and the cover hardness is the intermediate layer.
The hardness is 1 degree or more and 15 degrees or less as measured by JIS-C type hardness tester.
High in the full range, and the total thickness of the intermediate layer and cover is
2 to 5.5 mm, according to any one of claims 1 to 8.
Three-piece solid golf ball described. 10. The hardness of the intermediate layer is 1 to 8 more than the surface hardness of the core.
The three-piece solid golf ball according to claim 1 , wherein the three-piece solid golf ball has a high degree in the range of degrees. 11. The cover hardness is 1 to 13 than the intermediate layer hardness.
The three-piece solid golf ball according to claim 1 , wherein the three-piece solid golf ball has a high degree of degree.