JP4535271B2 - Multi-piece solid golf ball - Google Patents

Description

  The present invention relates to a multi-piece solid golf ball having a core composed of a plurality of layers, an intermediate layer, and a cover. More specifically, it provides resilience, feel and durability even for an amateur player with a low head speed. The present invention relates to a compatible multi-piece solid golf ball.

  In recent years, the demand for golf balls from players has been diversified and individualized due to an increase in the golf population, and various studies have been made on ball structures in order to meet such demands.

  For example, Patent Document 1: Japanese Patent Application Laid-Open No. 9-313643 discloses that by optimizing the hardness distribution of the core and further optimizing the hardness distribution of the entire ball including the core, the intermediate layer, and the cover. A golf ball that can simultaneously satisfy flying performance and durability, and good hit feeling and controllability is proposed. Patent Document 2: Japanese Patent Laid-Open No. 10-305114 discloses a solid core, an intermediate layer, and a cover. In the golf ball having a large number of dimples formed on the surface of the cover, the hardness balance between the core, the intermediate layer, and the cover is optimized, and the dimple element is optimized so that the head speed is related. A golf ball with improved feel and flying performance has been proposed. Furthermore, in Patent Document 3: Japanese Patent Application Laid-Open No. 2001-218875, in a multi-piece golf ball including a core, an intermediate layer, and a cover, the deflection hardness of a sphere in which the intermediate layer is coated on the core / the deflection hardness of the core is optimized. Thus, there has been proposed a golf ball that achieves both good feeling and improved flying performance. Further, Patent Document 4: Japanese Patent Application Laid-Open No. 2001-252374 proposes a golf ball that defines the relationship between the thickness and hardness of an intermediate layer in a multi-piece solid ball including a core, an intermediate layer, and a cover. Yes.

  However, these golf balls still have room for improvement from the viewpoint of resilience. In particular, when an amateur player with a low head speed is used, there has been a demand for a golf ball that can achieve both good resilience, feel and durability.

Japanese Patent Laid-Open No. 9-313643 JP 10-305114 A JP 2001-218875 A JP 2001-252374 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-piece solid golf ball that can achieve both good resilience, feel and durability when used by an amateur player with a low head speed. And

  As a result of intensive studies to achieve the above object, the present inventor has found that a multi-piece solid golf ball comprising a core composed of a plurality of layers, an intermediate layer covering the core, and a cover covering the intermediate layer Shore D hardness balance between the intermediate layer and the cover, initial velocity balance between the core and the sphere coated with the intermediate layer on the core, deflection hardness balance between the core and the sphere coated with the intermediate layer on the core By optimizing the golf ball, it is possible to realize a multi-piece solid golf ball that can achieve both good resilience, feel and durability when used by amateur players with low head speeds. It came to.

That is, the present invention provides the following multi-piece solid golf ball.
Claim 1:
In a multi-piece solid golf ball comprising a core composed of a plurality of layers, an intermediate layer covering the core, and a cover covering the intermediate layer, the intermediate layer is (a-1) an olefin-unsaturated carboxylic acid 2 Metallic ion neutralized product of original random copolymer and / or olefin-unsaturated carboxylic acid binary random copolymer and (a-2) olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer And / or metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer (a-1) / (a-2) = 100/0 to 0/100 (mass) Resin composition containing (A) ionomer resin and (B) non-ionomer thermoplastic elastomer in a ratio of (A) / (B) = 100/0 to 50/50 (mass ratio). For 100 parts by mass, (C) an organic fatty acid having a molecular weight of 280 to 1500 and / or a derivative thereof, 5 to 80 parts by mass, and (D) an unneutralized acid group in the resin component and the component (C). Each of the following conditions (1) to (3) is formed with a mixture formed by blending 0.1 to 10 parts by mass of a basic inorganic metal compound capable of neutralization :
(1): (Shore D hardness of cover) − (Shore D hardness of intermediate layer)> 0,
(2): (Initial velocity (m / s) of a sphere with an intermediate layer coated on the core) − (Initial velocity (m / s) of the core)> − 0.2 (Here, the initial velocity is the USGA Means the initial speed measured using the initial speed measuring device of the same system as the drum rotation type initial speedometer),
(3): 0.90 ≦ [(the deflection hardness of the sphere with the intermediate layer coated on the core) / (the deflection hardness of the core)] ≦ 1.00 (where the deflection hardness is the initial load on the spherical object) The amount of deformation (mm) from when 98 N (10 kgf) is loaded to when the final load of 1275 N (130 kgf) is loaded)
A multi-piece solid golf ball characterized by satisfying
Claim 2:
Further, the following conditions (4) to (9):
(4): The total thickness of the intermediate layer thickness (mm) and the cover thickness (mm) is 3.0 mm or less,
(5): The thickness (mm) of the cover is 0.5 mm or more and 2.0 mm or less,
(6): Shore D hardness of the cover is 55 or more and 70 or less,
(7): The thickness (mm) of the intermediate layer is 0.5 mm or more and 1.6 mm or less,
(8): Shore D hardness of the intermediate layer is 40 or more and 60 or less,
(9): The initial velocity of the golf ball is 76.5 m / s or more,
The golf ball according to claim 1, wherein:
Claim 3:
Furthermore, the following condition (10):
(10): The melt flow rate of the cover is 2 g / 10 min or more,
The golf ball according to claim 1 or 2, wherein:
Claim 4:
Furthermore, the following condition (11):
(11): 0.85 ≦ (deflection hardness of golf ball / deflection hardness of sphere in which core is covered with intermediate layer) ≦ 0.95,
The multi-piece solid golf ball according to claim 1, 2 or 3 satisfying
Claim 5 :
Furthermore, the following condition (12):
(12): ( JIS-C surface hardness of core surface) − ( JIS-C hardness of core center) ≧ 20
The multi-piece solid golf ball according to claim 1, wherein:
Claim 6 :
Further, the following condition (13):
(13): 5 ≧ ( JIS-C surface hardness of intermediate layer) − ( JIS-C surface hardness of core surface) ≧ −5
The multi-piece solid golf ball according to claim 1, wherein:

  The multi-piece solid golf ball of the present invention is a golf ball that can achieve both good resilience, feel and durability when used by an amateur player with a low head speed.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention is a multi-piece solid golf ball comprising a core composed of a plurality of layers, an intermediate layer covering the core, and a cover covering the intermediate layer. The following (1) to (3) Each condition,
(1): (Shore D hardness of cover) − (Shore D hardness of intermediate layer)> 0,
(2): (Initial velocity (m / s) of a sphere with an intermediate layer coated on the core) − (Initial velocity (m / s) of the core)> − 0.2 (Here, the initial velocity is the USGA Means the initial speed measured using the initial speed measuring device of the same system as the drum rotation type initial speedometer),
(3): 0.90 ≦ [(the deflection hardness of the sphere with the intermediate layer coated on the core) / (the deflection hardness of the core)] ≦ 1.00 (where the deflection hardness is the initial load on the spherical object) The amount of deformation (mm) from when 98 N (10 kgf) is loaded to when the final load of 1275 N (130 kgf) is loaded)
It is characterized by satisfying.
Here, in the present invention, the flexural hardness means that when a final load 1275 (130 kgf) is applied from a state in which an initial load 98 N (10 kgf) is applied to a spherical object such as a core, a sphere coated with an intermediate layer, and a golf ball. The amount of deformation (mm) up to.

As the material of the intermediate layer and / or cover in the present invention,
(A-1) a metal ion neutralized product of an olefin-unsaturated carboxylic acid binary random copolymer and / or an olefin-unsaturated carboxylic acid binary random copolymer;
(A-2) Metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer and / or olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer And
(A-1) / (a-2) = 100/0 to 0/100 (mass ratio) (A) ionomer resin included,
(B) a non-ionomer thermoplastic elastomer,
It is preferable that (A) / (B) = 100 / 0-50 / 50 (mass ratio).
For 100 parts by mass of the resin component containing the (A) ionomer resin and the (B) non-ionomer thermoplastic elastomer in a ratio of (A) / (B) = 100/0 to 50/50 (mass ratio),
(C) 5 to 80 parts by mass of an organic fatty acid having a molecular weight of 280 to 1500 and / or a derivative thereof;
(D) 0.1 to 10 parts by mass of a basic inorganic metal compound capable of neutralizing an unneutralized acid group in the resin component and the component (C);
It is more preferable that the mixture is formed by blending.

As the olefin in the component (a-1) and the component (a-2), an olefin having usually 2 or more carbon atoms and an upper limit of 8 or less, particularly 6 or less is preferably used. More specific examples of such olefins include ethylene, propylene, butene, pentene, hexene, heptene, octene and the like, and ethylene is particularly preferably used.
Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like, and acrylic acid and methacrylic acid are particularly preferably used.

  Examples of the unsaturated carboxylic acid ester in the component (a-2) include the lower alkyl esters of the unsaturated carboxylic acid described above, and more specifically, methyl methacrylate, ethyl methacrylate, propyl methacrylate. Butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and the like, and butyl acrylate (n-butyl acrylate, i-butyl acrylate) is particularly preferably used.

  The olefin-unsaturated carboxylic acid binary random copolymer of component (a-1) and the olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer of component (a-2) (hereinafter referred to as these) Are generally abbreviated as “random copolymer”), and are obtained by random copolymerizing the above-mentioned olefin, unsaturated carboxylic acid, and if necessary, unsaturated carboxylic acid ester by a known method. be able to.

The random copolymer is preferably one in which the content (acid content) of the unsaturated carboxylic acid is adjusted. In this case, the content of the unsaturated carboxylic acid contained in the component (a-1) is usually 4% by mass or more, preferably 6% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and the upper limit. Is usually 30% by mass or less, preferably 20% by mass or less, more preferably 18% by mass or less, and still more preferably 15% by mass or less. The content of the unsaturated carboxylic acid contained in the component (a-2) is usually 4% by mass or more, preferably 6% by mass or more, more preferably 8% by mass or more, and the upper limit is usually 15% by mass or less, preferably It is 12 mass% or less, More preferably, it is 10 mass% or less.
If the content of the unsaturated carboxylic acid contained in the component (a-1) and / or the component (a-2) is too small, the resilience may be lowered, and if it is too much, the workability may be lowered.

  The (a-1) component olefin-unsaturated carboxylic acid binary random copolymer neutralized metal ion and the (a-2) component olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer The polymer metal ion neutralized product (hereinafter sometimes collectively referred to as “random copolymer metal ion neutralized product”) is a part of the acid group in the random copolymer. Alternatively, it can be obtained by neutralizing the whole with metal ions.

Examples of metal ions that neutralize the acid groups in the random copolymer include Na ⁺ , K ⁺ , Li ⁺ , Zn ⁺⁺ , Cu ⁺⁺ , Mg ⁺⁺ , Ca ⁺⁺ , Co ⁺⁺ , and Ni. ⁺⁺ , Pb ^{++ and the} like can be mentioned. Among these, Na ⁺ , Li ⁺ , Zn ⁺⁺ and Mg ⁺⁺ are preferable, and Na ⁺ is particularly preferable from the viewpoint of improving resilience. is there.

  As a method of obtaining the metal ion neutralized product of the random copolymer using such metal ions, for example, the formate, acetate, nitrate of the metal ion with respect to the random copolymer having an acid group. Carbonate, bicarbonate, oxide, hydroxide, alkoxide and the like may be added for neutralization. The degree of neutralization of the acid groups by these metal ions is not particularly limited in the present invention.

Commercially available products can be used as the component (a-1) and the component (a-2).
Examples of the random copolymer of the component (a-1) include, for example, Nuclerel 1560, 1214, and 1035 (all manufactured by Mitsui DuPont Polychemical Co., Ltd.), ESCOR 5200, 5100, and 5000 (all manufactured by EXXONMOBIL CHEMICAL). Etc.
As the metal ion neutralized product of the random copolymer of the component (a-1), for example, Himilan 1554, 1557, 1601, 1605, 1706, AM7311 (all manufactured by Mitsui DuPont Polychemical Co., Ltd.), Surlyn 7930 (manufactured by DuPont, USA), Iotech 3110, 4200 (manufactured by EXXONMOBILCHEMICAL), etc.
As the random copolymer of the component (a-2), for example, Nuclerel AN4311, AN4318 (both manufactured by Mitsui DuPont Polychemical Co., Ltd.), ESCOR ATX325, ATX320, ATX310 (both manufactured by EXXONMOBIL CHEMICAL), etc. ,
As the metal ion neutralized product of the random copolymer of the component (a-2), for example, Himiran 1855, 1856, and AM7316 (both manufactured by Mitsui DuPont Polychemical Co., Ltd.), Surlyn 6320, 8320, and 9320, 8120 (all manufactured by DuPont USA), Iotech 7510, 7520 (all manufactured by EXXONMOBIL CHEMICAL), etc.
Each can be mentioned. These may be used alone or in combination of two or more.
Examples of the sodium neutralized ionomer resin suitable as the metal ion neutralized product of the random copolymer include Himiran 1605, 1601 and Surlyn 8120.

  In addition, the proportion of the component (a-2) in the total amount of the component (a-1) and the component (a-2) is usually 0% by mass or more, preferably 50% by mass or more, and usually the upper limit. 100% by mass or less.

The (B) non-ionomer thermoplastic elastomer is a component that is suitably blended from the viewpoint of further improving the feeling and resilience when hitting a golf ball. In the present invention, the (A) ionomer resin and the (B) non-ionomer thermoplastic elastomer may be collectively referred to as “resin component” in some cases.
More specific examples of such (B) non-ionomer thermoplastic elastomers include olefin elastomers, styrene elastomers, polyester elastomers, urethane elastomers, polyamide elastomers, and the like. From the viewpoint of enhancing, olefin elastomers and polyester elastomers are particularly preferably used.
A commercial item may be used as such (B) component, Dynalon (made by JSR) as an olefin type elastomer, Hytrel (made by Toray DuPont) etc. can be mentioned as a polyester type elastomer. These may be used alone or in combination of two or more.

  The proportion of the component (B) in the resin component is usually 0% by mass or more, preferably 20% by mass or more, and the upper limit is usually 50% by mass or less, preferably 40% by mass or less. If the proportion of the component (B) in the resin component exceeds 50% by mass, the compatibility of the components may be reduced, and the durability of the golf ball may be significantly reduced.

  The component (C) in the present invention is an organic fatty acid having a molecular weight of 280 or more and 1500 or less and / or a derivative thereof. The molecular weight is extremely small compared to the resin component, the melt viscosity of the mixture is appropriately adjusted, Since it is a component which contributes to the improvement of the property, it is preferably blended.

  The molecular weight of the organic fatty acid component (C) is usually 280 or more, preferably 300 or more, more preferably 330 or more, still more preferably 360 or more, and the upper limit is usually 1500 or less, preferably 1000 or less, more preferably 600 or less. More preferably, it is 500 or less. If the molecular weight is too low, the heat resistance may be inferior, and if it is too high, the fluidity may not be improved.

Examples of such organic fatty acids of component (C) include unsaturated organic fatty acids having a double bond or triple bond in the alkyl group, and saturated organic fatty acids in which the bond in the alkyl group is composed of only a single bond. It can be used suitably.
The number of carbon atoms in one molecule of the organic fatty acid is usually 18 or more, preferably 20 or more, more preferably 22 or more, still more preferably 24 or more, and the upper limit is usually 80 or less, preferably 60 or less, more preferably 40 or less, More preferably, it is 30 or less. If the number of carbon atoms is too small, not only may the result be inferior in heat resistance, but the content of acid groups will be too high, resulting in excessive interaction with acid groups contained in the resin component, and fluidity. The improvement effect may be reduced. On the other hand, when the number of carbon atoms is too large, the molecular weight increases, and thus the effect of fluidity modification may not be noticeable.

  More specifically, examples of the organic fatty acid of component (C) in the present invention include stearic acid, 12-hydroxystearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, lignoceric acid, and the like. Of these, stearic acid, arachidic acid, behenic acid, lignoceric acid, particularly behenic acid are preferably used.

Examples of the organic fatty acid derivative of the component (C) include metal soaps in which protons contained in the acid groups of the organic fatty acids described above are substituted with metal ions. In this case, examples of the metal ions include Na ⁺ , Li ⁺ , Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Mn ⁺⁺ , Al ⁺⁺⁺ , Ni ⁺⁺ , Fe ⁺⁺ , Fe ⁺⁺⁺ , Cu ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , Co ^{++ and the} like can be used, and Ca ⁺⁺ , Mg ⁺⁺ , and Zn ⁺⁺ are particularly preferable.

  More specifically, as the organic fatty acid derivative of component (C), for example, magnesium stearate, calcium stearate, zinc stearate, 12-hydroxy magnesium stearate, 12-hydroxy calcium stearate, 12-hydroxy zinc stearate, arachidic acid Examples include magnesium, calcium arachidate, zinc arachidate, magnesium behenate, calcium behenate, zinc behenate, magnesium lignocerate, calcium lignocerate, zinc lignocerate, among others, magnesium stearate, calcium stearate, stearic acid Zinc, magnesium arachidate, calcium arachidate, zinc arachidate, magnesium behenate, calcium behenate, behenic acid sub , Can be preferably used magnesium lignoceric acid, calcium lignoceric acid, lignoceric acid zinc. These may be used alone or in combination of two or more.

  Moreover, as such (C) component compounding quantity, it is 5 mass parts or more normally with respect to 100 mass parts of said resin components which consist of (A) and (B), Preferably it is 10 mass parts or more, More preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and the upper limit is usually 80 parts by mass or less, preferably 40 parts by mass or less, more preferably 25 parts by mass or less, and further preferably 22 parts by mass or less. If the blending amount of the component (C) is too small, the melt viscosity may be too low and the workability may be lowered, and if it is too much, the durability may be lowered.

  In the invention, a known metal soap-modified ionomer (USP5312857, USP5306760, WO98 / 46671, etc.) can be used as a mixture of the (A) ionomer resin and the component (C).

  The component (D) in the present invention is a basic inorganic metal compound capable of neutralizing an unneutralized acid group in the resin component and the component (C). When the component (D) is not blended and, for example, a metal soap-modified ionomer resin is used alone, an exchange reaction between the metal soap and the unneutralized acid group contained in the ionomer resin occurs during heating and mixing. In some cases, defects such as poor molding, poor coating film adhesion, and low rebound of the resulting molded product may occur. In view of such points, the component (D) is suitably blended in the present invention.

The component (D) preferably has high reactivity with the resin component and does not contain an organic acid in the reaction byproduct.
Examples of the metal ion in the component (D) include Li ⁺ , Na ⁺ , K ⁺ , Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Al ⁺⁺⁺ , Ni ⁺⁺ , Fe ⁺⁺ and Fe ^{+. ++} , Cu ⁺⁺ , Mn ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , Co ^++, etc. can be mentioned, and these may be used alone or in combination of two or more. As the component (D), known basic inorganic fillers containing these metal ions can be used. More specifically, for example, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, sodium hydroxide, Examples thereof include sodium carbonate, calcium oxide, calcium hydroxide, lithium hydroxide, and lithium carbonate. In particular, hydroxides or monoxides are recommended, and calcium hydroxide and magnesium oxide having high reactivity with the base resin are preferably used.

  As a compounding quantity with respect to 100 mass parts of said resin components of said (D) component, it is 0.1 mass part or more normally, Preferably it is 0.5 mass part or more, More preferably, it is 1 mass part or more, More preferably, it is 2 mass parts or more. The upper limit is usually 10 parts by mass or less, preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and still more preferably 5 parts by mass or less. When the blending amount of the component (D) is too small, the heat stability and the resilience may not be improved, and when it is too large, the heat resistance of the golf ball material is lowered due to the excessive basic inorganic metal compound. There is.

  The degree of neutralization of the mixture obtained by mixing the components (A) to (D) is usually 50 mol% or more, preferably 60 mol% or more, more preferably based on the total amount of acid groups in the mixture. Is 70 mol% or more, more preferably 80 mol% or more. By such high neutralization, for example, even when a metal soap-modified ionomer resin is used, an exchange reaction between the metal soap and unneutralized acid groups contained in the ionomer resin hardly occurs during heating and mixing, and thermal The possibility of impairing stability, moldability, and resilience is reduced.

  The material for the intermediate layer and / or cover in the present invention includes, in addition to the components (A) to (D), a pigment, a dispersant, an anti-aging agent, an ultraviolet absorber, a light stabilizer and the like. Additives can be blended. Although it does not restrict | limit especially as the compounding quantity, It is 0.1 mass part or more normally with respect to 100 mass parts of said resin components which consist of said (A) component and said (B) component, Preferably it is 0.5. The upper limit is usually 10 parts by mass or less, preferably 6 parts by mass or less, more preferably 4 parts by mass or less.

  The intermediate layer and / or cover material in the present invention can be obtained by heating and mixing the above-described components. For example, under a heating temperature of 150 to 250 ° C., a kneading type twin screw extruder, Banbury, kneader, etc. It can obtain by kneading using an internal mixer.

In the present invention, the core is formed in a plurality of layers, and it is particularly preferable to form the core in a two-layer structure of an inner layer core and an outer layer core. In this case, the diameter of the inner layer core is usually 15 mm or more, preferably 20 mm or more, more preferably 23 mm or more, and the upper limit is usually 35 mm or less, preferably 30 mm or less, more preferably 27 mm or less. If this diameter is too small, the low spin effect may not be sufficient and the flight distance may not be achieved. If this diameter is too large, the thickness of the outer layer core must be relatively reduced, and as a result, repeated impact durability may deteriorate.
As a material of such a core composed of a plurality of layers, a known rubber material such as polybutadiene or polyisoprene rubber can be used as a base material. For example, acrylic acid is used with respect to 100 parts by mass of cis-1,4-polybutadiene. , Α, β-monoethylenically unsaturated carboxylic acid such as methacrylic acid or neutralized product thereof, or a crosslinking agent such as a functional monomer such as trimethylolpropane methacrylate alone or in combination of two or more 10 parts by mass or more and 60 parts by mass or less, fillers such as zinc oxide and barium sulfate 5 parts by mass to 30 parts by mass, and peroxides such as dicumyl peroxide 0.5 parts by mass to 5 parts by mass Hereinafter, the rubber composition which mix | blended 0.1 mass part or more and 1 mass part or less of anti-aging agent as needed can be mentioned. As a method for producing such a core composed of a plurality of layers, the inner layer core can be formed by a method such as forming into a spherical shape by heating and compressing at 140 to 180 ° C. for 10 to 60 minutes according to a conventional method. .

  The base material of the outer layer core surrounding the inner layer core is the same or different rubber base material as the inner layer rubber base material described above.

  As a method of forming the outer layer core on the inner layer core surface, a pair of half cups are formed using a sheet-like unvulcanized rubber, and the inner layer core is further encapsulated in the cup, and heated under pressure. A molding method can be employed. For example, after a pair of hemispherical cup bodies are manufactured by primary vulcanization (semi-vulcanization), an inner layer core coated with a prefabricated outer layer core is placed on one hemispherical cup body, and the other hemispherical cup A method of performing secondary vulcanization (total vulcanization) with the body covered, or a rubber composition made into a sheet in an unvulcanized state to produce a pair of outer layer core sheets, the sheets being hemispherical After producing an unvulcanized hemispherical cup body by embossing with a half mold provided with protrusions, the pair of hemispherical cup bodies are put on an inner layer core manufactured in advance, at 140 to 180 ° C. for 10 to 60 minutes. By heating and compressing to form a sphere, a method in which the vulcanization process is divided into two stages can be suitably employed.

  In the present invention, the deflection hardness of the entire core is usually 3.0 mm or more, preferably 3.3 mm or more, more preferably 3.6 mm or more, and the upper limit is usually 6.0 mm or less, preferably 5.0 mm or less, more preferably It is 4.6 mm or less. If the deflection hardness is less than 3.0 mm, the spin of the golf ball may increase so that it may not fly or the feel of hitting may become hard. On the other hand, if it exceeds 6.0 mm, the resilience will be low and the ball will fly. It may disappear, the feeling of hitting may become too soft, or the durability to cracking when hitting repeatedly may deteriorate.

  The diameter of the entire core is usually 36.5 mm or more, preferably 37 mm or more, more preferably 37.5 mm or more, and the upper limit is usually 40 mm or less, preferably 39.5 mm or less, more preferably 39 mm or less. If it deviates from such a range, the durability to cracking during repeated hitting deteriorates, and the amount of spin may increase when hitting with a driver (W # 1), resulting in a loss of flight distance.

Furthermore, the specific gravity of the core is usually 1.05 g / cm ³ or more, preferably 1.15 g / cm ³ or more, and the upper limit is usually 1.35 g / cm ³ or less, preferably 1.25 g / cm ³ or less.

  Furthermore, the hardness at the core center is usually 30 or more, preferably 40 or more, more preferably 45 or more, and the upper limit is usually 60 or less, preferably 55 or less, more preferably 53 or less in terms of JIS-C hardness. When the JIS-C hardness at the center of the core exceeds 60, the spin increases so that it does not fly and the feel at impact may become hard. On the other hand, if the value is less than 30, the resilience will be low and will not fly, the feeling of hitting will be too soft, and the durability to cracking when repeatedly hitting may deteriorate. The hardness of the core surface is usually 65 or more, preferably 70 or more, more preferably 75 or more, and the upper limit is usually 90 or less, preferably 85 or less, more preferably 80 or less in terms of JIS-C hardness. When the JIS-C hardness of the core surface exceeds 80, the hitting feeling may become hard. On the other hand, when it is less than 65, the resilience becomes low and does not fly, the hitting feeling becomes too soft, and when hit repeatedly. The crack durability may be deteriorated. In general, the difference in hardness between the core surface and the intermediate layer surface is JIS-C hardness of ± 5, preferably ± 4, and more preferably ± 3. If the hardness relationship between the core surface and the intermediate layer surface deviates from the above range, it may not be possible to achieve both improvement in flying and imparting a good hit feeling.

  In the present invention, a golf ball having a core, an intermediate layer covering the core, and a cover covering the intermediate layer is formed using each of the materials described above. The solid golf ball has a Shore D hardness balance between the intermediate layer and the cover (condition (1) above), an initial velocity balance between the core and the sphere covered with the intermediate layer (of (2) above). Condition), by optimizing the flexural hardness balance (condition (3) above) between the core and the sphere whose core is covered with the intermediate layer, even for low head speed amateur players, An object of the present invention is to provide a golf ball capable of achieving both hit feeling and durability.

Further, from the viewpoint of providing a more excellent golf ball, the following conditions (4) to (13) can be suitably employed.
(4): The total thickness of the intermediate layer thickness (mm) and the cover thickness (mm) is 3.0 mm or less,
(5): The thickness (mm) of the cover is 0.5 mm or more and 2.0 mm or less,
(6): Shore D hardness of the cover is 55 or more and 70 or less,
(7): The thickness (mm) of the intermediate layer is 0.5 mm or more and 1.6 mm or less,
(8): Shore D hardness of the intermediate layer is 40 or more and 60 or less,
(9): The initial velocity of the golf ball is 76.5 m / s or more,
(10): MFR of the cover is 2 g / min or more,
(11): 0.85 ≦ (deflection hardness of golf ball / deflection hardness of sphere in which core is covered with intermediate layer) ≦ 0.95,
(12): ( JIS-C surface hardness of core surface) − ( JIS-C hardness of core center) ≧ 20
(13): 5 ≧ ( JIS-C surface hardness of intermediate layer) − ( JIS-C surface hardness of core surface) ≧ −5

[Conditions for (1)]
In the multi-piece solid golf ball of the present invention, the value of (Shore D hardness of the cover) − (Shore D hardness of the intermediate layer) is greater than 0, usually 5 or more, preferably 10 or more, and the upper limit is 30 or less, preferably Is 20 or less, more preferably 15 or less. If the difference is 0 or less, too much spin is applied and the flight distance decreases, and if the difference exceeds 30, the rebound becomes low and the flight distance decreases.

[Conditions for (2)]
In the multi-piece solid golf ball of the present invention, the value of (initial velocity (m / s) of a sphere with an intermediate layer coated on the core) − (initial velocity (m / s) of the core) is greater than −0.2. The value is preferably 0 or more, more preferably 0.1 or more, and particularly preferably 0.2 or more. If the difference is −0.2 or less, the rebound is insufficient and the flight distance is reduced. As a means satisfying the condition (2), a highly repulsive material is required for the intermediate layer. If the intermediate layer is hardened and the core is made soft and has low resilience, the condition (2) will be satisfied. However, if the other requirements of the claim are not satisfied at the same time, the effect of the present invention cannot be achieved.
The “initial speed (m / s)” was measured using an initial speed measuring device of the same type as a USGA drum rotary initial speed meter approved by R & A. The ball was temperature-controlled at 23 ± 1 ° C. for 3 hours or more and then tested in a room at room temperature 23 ± 2 ° C. 5. Using a 250 pound (113.4 kg) head (striking mass), hit the ball at a hitting speed of 143.8 ft / s (43.83 m / s) and hit a dozen balls 4 times each. The initial speed (m / s) was calculated by measuring the time required to pass between 28 ft (1.91 m). This cycle was performed in about 15 minutes.

[Regarding condition (3)]
In the multi-piece solid golf ball of the present invention, the value of (deflection hardness of the sphere with the core covered with the intermediate layer) / (deflection hardness of the core) is 0.90 or more, preferably 0.92 or more, more preferably 0. 0.94 or more, and the upper limit is 1 or less, preferably 0.98 or less, more preferably 0.96 or less. If the ratio is less than 0.90, the feeling of hitting with the putter becomes hard, and the spin by W # 1 hitting may increase and the flight distance may not come out. If the ratio exceeds 1, spin increases when W # 1 is hit, and the flight distance may not be obtained, and repeated hitting durability may deteriorate.
As specific means for designing the golf ball so as to satisfy the condition (3), the shore D hardness of the intermediate layer is set in the range of about 40 to 60, and the intermediate layer thickness and core hardness are set to appropriate values. The method of setting to can be adopted.

[Regarding condition (4)]
In the multi-piece solid golf ball of the present invention, the total thickness of the intermediate layer (mm) and the cover (mm) is preferably 1.5 mm or more, more preferably 2.0 mm or more, and particularly preferably 2. It is 4 mm or more and the upper limit is 3.0 mm or less, preferably 2.8 mm or less, more preferably 2.6 mm or less. If the total thickness is less than 1.5 mm, the crack durability during repeated hitting deteriorates, and if the total thickness exceeds 3.0 mm, the spin at the time of hitting W # 1 increases and the flight distance does not appear.

[Regarding condition (5)]
In the multi-piece solid golf ball of the present invention, the cover thickness (mm) is usually 0.5 mm or more, preferably 0.9 mm or more, more preferably 1.1 mm or more, and the upper limit is usually 2.0 mm or less, preferably 1. .6 mm or less, more preferably 1.3 mm or less. If the cover thickness is less than 0.5 mm, the durability to cracking during repeated impacts may deteriorate, while if it exceeds 2.0 mm, the feel during approach or putter impacts may deteriorate.

[Regarding condition (6)]
In the multi-piece solid golf ball of the present invention, the Shore D hardness of the cover is usually 55 or more, preferably 57 or more, more preferably 60 or more, and the upper limit is usually 70 or less, preferably 66 or less, more preferably 63 or less. . When the Shore D hardness is less than 55, the spin distance is excessively applied or the rebound is insufficient and the flight distance is decreased, and the scratch resistance may be deteriorated. On the other hand, if the Shore D hardness exceeds 70, the durability against cracking due to repeated hitting may deteriorate, and the hit feeling of short games and putters may deteriorate.

[Regarding condition (7)]
In the multi-piece solid golf ball of the present invention, the thickness (mm) of the intermediate layer is usually 0.5 mm or more, preferably 0.8 mm or more, more preferably 1.1 mm or more, and the upper limit is usually 1.6 mm or less, preferably It is 1.4 mm or less, more preferably 1.3 mm or less. If the thickness of the intermediate layer is less than 0.5 mm, the durability against cracking due to repeated impacts is deteriorated, and the rebound may be reduced and the flight distance may not be obtained. On the other hand, if it exceeds 1.6 mm, the spin at the time of hitting with the driver may increase so that the flight distance may not be obtained.

[Regarding condition (8)]
In the multi-piece solid golf ball of the present invention, the Shore D hardness of the intermediate layer is usually 40 or more, preferably 45 or more, more preferably 48 or more, and the upper limit is usually 60 or less, preferably 55 or less, more preferably 52 or less. is there. In addition, the shore D hardness of an intermediate | middle layer means the shore D hardness when the material which forms an intermediate | middle layer is made into a sheet form. If the Shore D hardness is less than 40, spin may be applied too much, or rebound may be insufficient, resulting in a decrease in flight distance. On the other hand, when the Shore D hardness exceeds 60, durability against cracking due to repeated hitting may deteriorate, and the hit feeling of short games and putters may deteriorate.

[Regarding condition (9)]
In the multi-piece solid golf ball of the present invention, the initial velocity of the golf ball is usually 76.5 m / s or more, preferably 76.8 m / s or more, more preferably 77.0 m / s or more, and the upper limit is usually 77.724 m. / S or less. If it is too low, the flight distance will not come out. If it exceeds the upper limit of 77.724 m / s, it becomes out of the standard defined by R & A (USGA) and cannot be registered as a certified ball.

[Regarding condition (10)]
In the multi-piece solid golf ball of the present invention, the MFR of the cover material is usually 2 g / 10 minutes or more, preferably 2.5 g / 10 minutes or more, more preferably 3.0 g / 10 minutes or more. If the MFR is less than 2 g / 10 minutes, molding may be difficult, or the sphericity of the ball obtained by molding may be reduced, resulting in increased variation in flying. Here, the melt flow rate (sometimes abbreviated as “MFR”) is a value (g / 10) measured at a test temperature of 190 ° C. and a test load of 21.18 N (2.16 kgf) in accordance with JIS-K6760. And the same applies in the present invention.

[Regarding condition (11)]
In the multi-piece solid golf ball of the present invention, (the deflection hardness of the golf ball / the deflection hardness of the sphere having the core covered with the intermediate layer) is usually 0.85 or more, preferably 0,87 or more, and more preferably 0.8. 88 or more, and the upper limit is usually 0.95 or less, preferably 0.93 or less, more preferably 0.92 or less. If the value is too small or too large, the spin in W # 1 increases too much, and as a result, the flight distance may not be achieved.
As a specific means for designing the golf ball so as to satisfy the condition (11), a method of setting the cover hardness, the cover thickness, and the deflection hardness of the sphere covered with the intermediate layer to appropriate values can be adopted. .

[Regarding condition (12)]
In the multi-piece solid golf ball of the present invention, ( JIS-C surface hardness of core surface)-( JIS-C hardness of core center) is usually 20 or more, preferably 23 or more, more preferably 25 or more, and the upper limit. Is usually 40 or less, preferably 30 or less. If the value is too small, the low spin effect may not be sufficient and the flight distance may not be achieved. If the value is too large, the repeated impact durability may deteriorate.
[Regarding condition (13)]
In the multi-piece solid golf ball of the present invention, (the JIS-C surface hardness of the intermediate layer) − (the JIS-C surface hardness of the core surface) is −5 or more, preferably −4 or more, more preferably −3 or more. The upper limit is usually +5 or less, preferably +4 or less, more preferably +3 or less. If it deviates from the above range, the balance between the flying performance and the hit feeling may not be optimal.

  In addition, the multi-piece solid golf ball of the present invention can be in compliance with golf rules for competition purposes, and can be formed to have a diameter of 42.67 mm or more and a mass of 45.93 g or less. The upper limit of the diameter is preferably 44.0 mm or less, more preferably 43.5 mm or less, most preferably 43.0 mm or less, and the lower limit of the mass is preferably 44.5 g or more, more preferably 44.8 g or more, even more preferably. Is 45.0 g or more, particularly preferably 45.1 g or more.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Examples 1 to 3, Comparative Examples 1 to 5]
The rubber composition obtained with the formulation (parts by mass) shown in Table 1 was vulcanized at 155 ° C. for 15 minutes, and then its surface was polished to prepare an inner layer core. On the other hand, a rubber composition obtained in the formulation (parts by mass) shown in Table 2 was made into a sheet in an unvulcanized state to form a pair of outer layer core sheets, and the sheet was provided with a hemispherical protrusion. Embossed by the mold. After that, the outer layer core sheet is vulcanized at 155 ° C. for 15 minutes after covering the inner core with unvulcanized rubber embossed along the cavity of the mold, and then the surface is polished to form the inner and outer layers 2 A layer core was created.

Next, the intermediate layer material and the cover material having the composition shown in Table 3 were coated by injection molding to obtain a multi-piece golf ball.
Table 4 shows the evaluation results of the obtained golf balls.

ポリブタジエンＡ
商品名ＢＲ０１（ＪＳＲ社製）
ポリブタジエンＢ
商品名ＢＲ７３０（ＪＳＲ社製）
ポリイソプレンゴム
商品名ＩＲ２２００（ＪＳＲ社製）
過酸化物（１）
ジクミルパーオキサイド、商品名パークミルＤ（日本油脂社製）
過酸化物（２）
１，１ビス（ｔ−ブチルパーオキシ）３，３，５−トリメチルシクロヘキサン、商品名パーヘキサ３Ｍ−４０（日本油脂社製）
老化防止剤
ノクラックＮＳ−６（大内新興化学工業社製）
ステアリン酸亜鉛
商品名 ジンクステアレートＧ（日本油脂社製）

Polybutadiene A
Product name BR01 (manufactured by JSR)
Polybutadiene B
Product name BR730 (manufactured by JSR)
Polyisoprene rubber product name IR2200 (manufactured by JSR)
Peroxide (1)
Dicumyl peroxide, trade name Park Mill D (manufactured by NOF Corporation)
Peroxide (2)
1,1bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, trade name perhexa 3M-40 (manufactured by NOF Corporation)
Anti-aging agent NOCRACK NS-6 (Ouchi Shinsei Chemical Co., Ltd.)
Zinc stearate trade name zinc stearate G (manufactured by Nippon Oil & Fats Co., Ltd.)

サーリン８１２０，７９３０，９９４５
デュポン社製アイオノマー
ＡＭ７３１１，７３１７，７３１８
三井デュポンポリケミカル社製アイオノマー。７３１１；マグネシウム系アイオノマー、７３１７；酸含量１８％の亜鉛系アイオノマー、７３１８；酸含量１８％のナトリウム系アイオノマー。
ハイミラン１７０６，１６０５，１８５５
三井デュポンポリケミカル社製アイオノマー
ＡＮ４３１８
三井デュポンポリケミカル社製ニュクレル
ハイトレル３０４６
東レデュポン社製ポリエステルエラストマー
ダイナロン６１００Ｐ
ＪＳＲ社製水添ポリマー
ベヘニン酸
日本油脂社製ＮＡＡ２２２−Ｓ（ビーズ）
水酸化カルシウム
白石工業社製ＣＬＳ−Ｂ
ＭＦＲ(g/10min)
ＪＩＳ−Ｋ６７６０［試験温度１９０℃，試験荷重２１Ｎ（２．１６ｋｇｆ）に従って測定した材料のメルトフローレート］

Surlyn 8120, 7930, 9945
DuPont ionomer
AM7311, 7317, 7318
An ionomer manufactured by Mitsui DuPont Polychemicals. 7311; Magnesium ionomer, 7317; Zinc ionomer with 18% acid content, 7318; Sodium ionomer with 18% acid content.
High Milan 1706, 1605, 1855
Ionomer made by Mitsui DuPont Polychemical Co., Ltd.
AN4318
Nucler made by Mitsui DuPont Polychemical Co., Ltd.
Hytrel 3046
Polyester elastomer made by Toray DuPont
Dynalon 6100P
Hydrogenated polymer manufactured by JSR
Behenic acid manufactured by NOF Corporation NAA222-S (beads)
CLS-B made by calcium hydroxide Shiroishi Kogyo Co., Ltd.
MFR (g / 10min)
JIS-K6760 [Melt flow rate of material measured according to a test temperature of 190 ° C. and a test load of 21 N (2.16 kgf)]

The distance when struck at a head speed of 35m / s with a W # 1 club in flying golf swing robot was measured. The W # 1 club used TourStage V36 Loft 12.5 ° manufactured by Bridgestone Sports. The flight distance was evaluated according to the following criteria.
○: Total flight distance of 160.0 m or more ×: Total flight distance of less than 160.0 m

W # 1 feeling and putter feeling A sensory evaluation was conducted by 10 amateur golfers having a head speed of 35 to 40 m / s. Evaluation was made according to the following criteria.
○: 7 or more out of 10 felt good hit feeling ×: Less than 4 out of 10 people felt good hit feeling

Evaluation was made based on the number of times that the ball surface started to crack when a W # 1 club was attached to the cracking durability golf hitting robot and hit repeatedly at a head speed of 40 m / s. The average value of each ball N = 3 was used as the evaluation target value. Each index was evaluated according to the following criteria when the number of times that the crack in Example 1 began to crack was set to 100.
○: Index 95 or higher ×: Index less than 95

A scratch-resistant non-plated pitching sand wedge was set on a striking robot, hit once at a head speed of 40 m / s, and the surface of the ball was visually observed and evaluated according to the following criteria.
○: Can still be used ×: Cannot be used anymore

As for Comparative Example 1, the cover is too soft, the resilience is low, and there are too many spins so that the flight distance does not come out.
In Comparative Example 2, the core has a single layer, does not have low spin, and does not have a sufficient flight distance.
Regarding Comparative Example 3, since (initial velocity (m / s) of a sphere in which an intermediate layer is coated on a core) − (initial velocity (m / s) of a core) is smaller than −0.2, ball repulsion Insufficient sex and flight distance.
As for Comparative Example 4, the intermediate layer is too hard, and when W # 1 strikes, too much spin is applied and the flight distance is insufficient. In addition, it feels hard with a putter and is inferior in cracking durability when repeatedly hit.
As for Comparative Example 5, the intermediate layer is too soft, and the spin is excessively applied when W # 1 is hit, so that the flight distance is insufficient. Further, the cover and the intermediate layer are not sufficiently adhered, and the crack durability during repeated impact is poor.

Claims (6)

In a multi-piece solid golf ball comprising a core composed of a plurality of layers, an intermediate layer covering the core, and a cover covering the intermediate layer, the intermediate layer is (a-1) an olefin-unsaturated carboxylic acid 2 Metallic ion neutralized product of original random copolymer and / or olefin-unsaturated carboxylic acid binary random copolymer and (a-2) olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer And / or metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ternary random copolymer (a-1) / (a-2) = 100/0 to 0/100 (mass) Resin composition containing (A) ionomer resin and (B) non-ionomer thermoplastic elastomer in a ratio of (A) / (B) = 100/0 to 50/50 (mass ratio). For 100 parts by mass, (C) an organic fatty acid having a molecular weight of 280 to 1500 and / or a derivative thereof, 5 to 80 parts by mass, and (D) an unneutralized acid group in the resin component and the component (C). Each of the following conditions (1) to (3) is formed with a mixture formed by blending 0.1 to 10 parts by mass of a basic inorganic metal compound capable of neutralization :
(1): (Shore D hardness of cover) − (Shore D hardness of intermediate layer)> 0,
(2): (Initial velocity (m / s) of a sphere with an intermediate layer coated on the core) − (Initial velocity (m / s) of the core)> − 0.2 (Here, the initial velocity is the USGA Means the initial speed measured using the initial speed measuring device of the same system as the drum rotation type initial speedometer),
(3): 0.90 ≦ [(the deflection hardness of the sphere with the intermediate layer coated on the core) / (the deflection hardness of the core)] ≦ 1.00 (where the deflection hardness is the initial load on the spherical object) The amount of deformation (mm) from when 98 N (10 kgf) is loaded to when the final load of 1275 N (130 kgf) is loaded)
A multi-piece solid golf ball characterized by satisfying Further, the following conditions (4) to (9):
(4): The total thickness of the intermediate layer thickness (mm) and the cover thickness (mm) is 3.0 mm or less,
(5): The thickness (mm) of the cover is 0.5 mm or more and 2.0 mm or less,
(6): Shore D hardness of the cover is 55 or more and 70 or less,
(7): The thickness (mm) of the intermediate layer is 0.5 mm or more and 1.6 mm or less,
(8): Shore D hardness of the intermediate layer is 40 or more and 60 or less,
(9): The initial velocity of the golf ball is 76.5 m / s or more,
The golf ball according to claim 1, wherein: Furthermore, the following condition (10):
(10): The melt flow rate of the cover is 2 g / 10 min or more,
The golf ball according to claim 1 or 2, wherein: Furthermore, the following condition (11):
(11): 0.85 ≦ (deflection hardness of golf ball / deflection hardness of sphere in which core is covered with intermediate layer) ≦ 0.95,
The multi-piece solid golf ball according to claim 1, 2 or 3 satisfying Furthermore, the following condition (12):
(12): ( JIS-C surface hardness of core surface) − ( JIS-C hardness of core center) ≧ 20
The multi-piece solid golf ball according to claim 1, wherein: Furthermore, the following condition (13):
(13): 5 ≧ ( JIS-C surface hardness of intermediate layer) − ( JIS-C surface hardness of core surface) ≧ −5
The multi-piece solid golf ball according to claim 1, wherein: