JP5286764B2 - Multi-piece solid golf ball - Google Patents

Description

  The present invention relates to a multi-piece solid golf ball formed by laminating a core, an envelope layer, an intermediate layer, and a cover layer. More specifically, the present invention satisfies professional flight performance and control performance for professionals and advanced players. In addition, the present invention relates to a multi-piece solid golf ball having a good feel and excellent scratch resistance.

  Conventionally, various golf balls have been developed as golf balls for professionals and advanced players, and above all, from the point of achieving superior flight distance performance in the high head speed area and controllability in iron shots and approach shots, Multi-piece solid golf balls having a function that optimizes the hardness relationship of each layer of the intermediate layer and the cover layer covering the core are widely used. In addition to the flying performance, the feel at the time of hitting and the spin amount of the ball after hitting the club greatly affect the control of the ball. It is also an important theme to optimize the thickness and hardness of the steel. In addition, repeated hitting durability resulting from repeated hitting of the golf ball with various clubs, and generation of crumbs (scratch resistance) observed on the ball surface are also required. The aspect of protection is also an important theme in developing the ball.

  As such a golf ball, the outer layer cover of JP-A-2003-190330, JP-A-2004-049913, JP-A-2004-97802, JP-A-2005-319287, etc. is mainly made of thermoplastic polyurethane. A three-piece solid golf ball formed as is proposed. However, this golf ball has an inadequate realization of a low spin at the time of hitting a driver, and a golf ball that further increases a flight distance is desired from the viewpoint of professionals and advanced players.

  On the other hand, for further pursuit of golf ball flight, etc., each layer in the ball structure is made into four layers, that is, the intermediate layer covering the core and the cover layer are made into three layers, and the ball structure is internally changed into multiple layers. Proposals have been made. For example, JP 2004-180822 A, JP 10-127818 A, JP 10-127819 A, JP 10-295852 A, US Pat. Nos. 5,816,937, 6,152,834, Nos. 6123630, 6468169, 6045460, 6248027, 6117026, and 6277636 are proposed.

  However, these proposed golf balls have a poor balance of flight distance and controllability as golf balls suitable for advanced players, and low spin at the time of driver hitting is insufficient to achieve the total flight distance. There was a limit to increasing this.

JP 2003-190330 A JP 2004-049913 A Japanese Patent Laid-Open No. 2004-97802 JP 2005-319287 A JP 2004-180822 A Japanese Patent Laid-Open No. 10-127818 Japanese Patent Laid-Open No. 10-127819 JP-A-10-295852 US Pat. No. 5,816,937 US Pat. No. 6,152,834 US Pat. No. 6,123,630 US Pat. No. 6,468,169 US Pat. No. 6,045,460 US Pat. No. 6,248,027 US Pat. No. 6,117,026 US Pat. No. 6,277,036

  The present invention has been made in view of the above circumstances, and provides a multi-piece solid golf ball with excellent flying resistance and controllability that can be satisfied by professionals and advanced players, as well as excellent durability against cracking and abrasion resistance during repeated impacts. The purpose is to do.

  In the present invention, the basic structure of the golf ball design is that polyurethane is the outermost layer and the outer layer covering the core has a multilayer structure of three or more layers of an envelope layer, an intermediate layer, and a cover. The cover is made of relatively soft polyurethane as the outermost layer, so that the approach spin performance that can be satisfied by professionals and advanced players and a high level of abrasion resistance can be obtained. By using a material harder than the core surface and the intermediate layer for the envelope layer, the ball can be spun at the time of W # 1 hit. And in each layer of the core-enveloping layer-intermediate layer-cover, there is a hardness relationship of cover material hardness <intermediate layer material hardness <envelopment layer material hardness> core surface hardness, and the core diameter, intermediate layer and cover layer thickness By optimizing the relationship, the above-described conventional problems can be solved by the synergistic effect of the hardness relationship and the layer thickness relationship. That is, when the golf ball of the present invention is used by professionals and advanced players, it has a sufficiently satisfactory flight and controllability, and also exhibits excellent cracking durability and abrasion resistance during repeated hitting. The effects are unexpected, and therefore, the present inventor has found that the above-described problem can be solved by the above-described configuration of the present invention, and has completed the present invention.

Accordingly, the present invention provides the following multi-piece solid golf ball.
[1] A multi-piece solid golf ball comprising a core, an envelope layer covering the core, an intermediate layer covering the core, and a cover covering the core and having a plurality of dimples formed on the surface thereof. The core is formed of a rubber material as a main material, the core has a diameter of 31 mm or more, the envelope layer and the intermediate layer are formed of the same or different resin materials as the main material, and the cover is mainly made of polyurethane. The thickness of the envelope layer, the intermediate layer and the cover is formed as a material,
Satisfying the relationship of cover thickness <interlayer thickness <envelopment layer thickness, and the surface hardness (durometer D hardness) of the core and the material hardness (durometer D hardness) of the envelope layer, intermediate layer and cover are as follows. ,
Cover material hardness <Intermediate layer material hardness <Enveloping layer material hardness> Core surface hardness
The value obtained by subtracting the core surface hardness from the envelope layer material hardness is 18 to 25, the value obtained by subtracting the intermediate layer material hardness from the envelope layer material hardness is 1 to 4, and A value V _{0 obtained} by dividing the space volume of the dimple below the plane surrounded by the edge of the dimple by a cylindrical volume having the plane as the bottom surface and the maximum depth of the dimple from the bottom surface as a height is 0.35 or more 0 The VR value occupying the ball ball volume assuming that the dimple volume formed below the plane surrounded by the dimple edges is not present is 0.6% or more and 1.0 or less. % Multi-piece solid golf ball characterized by
[ 2 ] The multi-piece solid golf ball according to [ 1 ], wherein the resin component forming the envelope layer includes an ionomer resin having an acid content of 16% by mass or more.
[ 3 ] The resin component forming the cover is
(A) a thermoplastic polyurethane material;
(B) An isocyanate masterbatch in which an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule is dispersed in a thermoplastic resin (b-2) that does not substantially react with isocyanate. A multi-piece solid golf ball according to [ 1] or [2 ], comprising an isocyanate mixture containing
[ 4 ] The material hardness (durometer D hardness) of the envelope layer, the intermediate layer and the cover is as follows:
60 ≦ enveloping layer material hardness ≦ 70,
55 ≦ interlayer material hardness ≦ 70,
30 ≤ Cover material hardness ≤ 55
The multi-piece solid golf ball according to any one of [1] to [ 3 ].
[ 5 ] In the golf ball, the deflection amount (mm) from when the initial load 98N (10 kgf) to the final load 1275N (130 kgf) is applied to the ball and the core is 2.0 mm ≦ ball deflection amount, respectively. ≤ 3.0mm,
3.5mm ≦ Core deflection ≦ 6.0mm
The multi-piece solid golf ball according to any one of [1] to [ 4 ].

  According to the golf ball of the present invention, polyurethane is used as the main material for the cover, and the thickness and hardness of each of the envelope layer, the intermediate layer, and the cover are optimized as described above, and the core diameter is set to a certain size or more. By setting it, the ball spins at the time of a full shot by the driver, further increasing the flight distance of the ball and good controllability, and excellent crack durability and scratch resistance when repeatedly hit It is a multi-layered golf ball that is very useful as a golf ball for professionals and advanced players.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, the multi-piece solid golf ball of the present invention includes a core 1, an envelope layer 2 that covers the core, an intermediate layer 3 that covers the envelope layer, and an intermediate layer that covers the intermediate layer. A golf ball G having four or more layers having a cover 4 to be processed. In addition, many dimples D are usually formed on the surface of the cover 4. The core 1 or the intermediate layer 3 is not limited to a single layer and can be formed in a plurality of layers of two or more layers.

  In the present invention, the diameter of the core is defined as 31 mm or more, preferably 32.5 mm or more, and more preferably 34 mm or more. As an upper limit, Preferably it is 38 mm or less, More preferably, it is 37 mm or less, More preferably, it is 36 mm or less. If the core diameter deviates from this range, the initial velocity of the ball may become low, or the flight distance may not be extended due to the low spin effect after hitting the ball.

  The surface hardness of the core is not particularly limited, but is preferably 35 or more, more preferably durometer D hardness (measured by a type D durometer based on ASTM D2240, and the same meaning for the explanation of hardness in each layer below). The upper limit is preferably 60 or less, more preferably 55 or less, and still more preferably 50 or less. If it is below the above range, there is a case where the rebound is insufficient and the flight distance cannot be obtained, or the crack durability when repeatedly hit is deteriorated. On the other hand, if the above range is exceeded, the hit feeling at the time of a full shot may become too hard, or the spin amount may become too large to cause a flight distance.

  The amount of deflection when the core is loaded, that is, the amount of deflection (mm) from when the initial load 98N (10 kgf) to the final load 1275N (130 kgf) is applied to the core is not particularly limited. It is preferable to adjust to 3.5 mm or more, more preferably 3.8 mm or more, still more preferably 4.2 mm or more, and the upper limit value is preferably 6.0 mm or less, more preferably 5.6 mm or less. More preferably, it is 5.2 mm or less. If this value is too small, the rebound of the core will be insufficient and the flight distance will be insufficient, and the cracking durability during repeated impacts may deteriorate. On the other hand, if this value is too large, the hit feeling at the time of a full shot may become too hard, or the spin amount may become too large to increase the flight distance.

The core surface hardness is preferably softer than the material hardness of the envelope layer. In this case, the difference between the envelope layer material hardness and the core surface hardness is 18 or more, and the upper limit is 25 or less. If it deviates from the above range, the hardness of the entire ball becomes inadequate, feeling may be deteriorated, rebound may be insufficient, or a desired flight distance may not be obtained due to insufficient low spin effect.

  The solid core can be formed using a rubber composition containing, for example, a co-crosslinking agent, an organic peroxide, an inert filler, an organic sulfur compound, and the like. It is preferable to use polybutadiene as the base rubber of the rubber composition.

  The rubber component polybutadiene has a cis-1,4-bond in the polymer chain of 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 95% by mass or more. Is preferred. If there are too few cis-1,4-bonds in the bonds in the molecule, the resilience may decrease.

  Further, the content of 1,2-vinyl bond contained in the polybutadiene is usually 2% by mass or less, preferably 1.7% by mass or less, more preferably 1.5% by mass or less in the polymer chain. . If the content of 1,2-vinyl bond is too large, the resilience may be lowered.

  The polybutadiene used in the present invention is preferably synthesized with a rare earth element-based catalyst or a Group VIII metal compound catalyst from the viewpoint of obtaining a vulcanized molded product of a rubber composition having good resilience. In particular, those synthesized with a rare earth element-based catalyst are preferable.

  Such a rare earth element-based catalyst is not particularly limited. For example, a catalyst obtained by combining a lanthanum series rare earth element compound with an organoaluminum compound, an alumoxane, a halogen-containing compound, and a Lewis base as necessary. Can be mentioned.

  Examples of the lanthanum series rare earth element compounds include metal halides having an atomic number of 57 to 71, carboxylates, alcoholates, thioalcolates, and amides.

  In the present invention, in particular, the use of a neodymium-based catalyst using a neodymium compound as a lanthanum series rare earth element compound results in a polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds. These are preferable because they are obtained with excellent polymerization activity. Specific examples of these rare earth element-based catalysts are described in JP-A-11-35633, JP-A-11-164912, and JP-A-2002-293996. Can be preferably mentioned.

  In order to improve the resilience, the polybutadiene synthesized using a lanthanum series rare earth element compound-based catalyst is preferably contained in the rubber component in an amount of 10% by mass or more, preferably 20% by mass or more, particularly 40% by mass or more. .

  In addition to the polybutadiene, other rubber components can be blended with the rubber base material as long as the effects of the present invention are not impaired. Examples of the rubber component other than the polybutadiene include polybutadiene other than the polybutadiene, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber.

  Examples of the co-crosslinking agent include unsaturated carboxylic acids and unsaturated carboxylic acid metal salts.

  Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Acrylic acid and methacrylic acid are particularly preferably used.

  Although it does not specifically limit as a metal salt of unsaturated carboxylic acid, For example, what neutralized the said unsaturated carboxylic acid with the desired metal ion is mentioned. Specific examples include zinc salts such as methacrylic acid and acrylic acid, magnesium salts, and the like. In particular, zinc acrylate is preferably used.

  The unsaturated carboxylic acid and / or metal salt thereof is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and preferably as an upper limit with respect to 100 parts by mass of the base rubber. 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 45 parts by mass or less, and most preferably 40 parts by mass or less. If the blending amount is too large, it may become too hard and unbearable feel may occur, and if the blending amount is too small, the resilience may decrease.

  Commercially available products can be used as the organic peroxide. For example, Park Mill D (Nippon Yushi Co., Ltd.), Perhexa 3M, Perhexa C-40 (Nippon Yushi Co., Ltd.), Luperco 231XL (Atochem) Etc.) can be preferably used. These may be used alone or in combination of two or more.

  The organic peroxide is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, and most preferably 0, with respect to 100 parts by mass of the base rubber. The upper limit is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, still more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. If the blending amount is too large or too small, it may not be possible to obtain suitable feel, durability and resilience.

  As the inert filler, for example, zinc oxide, barium sulfate, calcium carbonate and the like can be suitably used. These may be used individually by 1 type and may use 2 or more types together.

  The compounding amount of the inert filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 50 parts by mass or less, more preferably 45 parts by mass or less as the upper limit, with respect to 100 parts by mass of the base rubber. More preferably, it is 40 parts by mass or less, and most preferably 35 parts by mass or less. If the blending amount is too large or too small, it may not be possible to obtain an appropriate mass and suitable resilience.

  Furthermore, an antiaging agent can be mix | blended as needed, For example, as a commercial item, Nocrack 200, NS-6, NS-30 (Ouchi Shinsei Chemical Co., Ltd. product), Yoshinox 425 (Yoshitomi) Pharmaceutical Co., Ltd.). These may be used individually by 1 type and may use 2 or more types together.

  The amount of the anti-aging agent is preferably 0 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, and preferably 3 as an upper limit with respect to 100 parts by mass of the base rubber. Not more than mass parts, more preferably not more than 2 parts by mass, still more preferably not more than 1 part by mass, most preferably not more than 0.5 parts by mass. If the amount is too large or too small, it may not be possible to obtain suitable resilience and durability.

  The core is preferably blended with an organic sulfur compound in order to improve the resilience of the golf ball and increase the initial velocity of the golf ball.

  The organic sulfur compound is not particularly limited as long as it can improve the resilience of the golf ball, and examples thereof include thiophenols, thionaphthols, halogenated thiophenols, and metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol, zinc salt of pentachlorothiophenol, zinc salt of pentafluorothiophenol, zinc salt of pentabromothiophenol, Examples include zinc salt of parachlorothiophenol, diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, dithiobenzoyl polysulfide, and the like. Particularly, zinc salt of pentachlorothiophenol is preferable. Used for.

  The amount of such an organic sulfur compound is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 5 parts by mass or less as the upper limit, with respect to 100 parts by mass of the base rubber. It is recommended that it is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2.5 parts by mass or less. If the blending amount is too large, the effect reaches a peak, and further effects may not be observed. If the blending amount is too small, the blending effect may not be sufficiently achieved.

Next, the envelope layer will be described below.
The material hardness of the envelope layer is not particularly limited, but is preferably 50 or more, more preferably 60 or more, and still more preferably 62 or more as the durometer D hardness, and the upper limit is preferably 75 or less, more preferably 70 or less, more preferably 68 or less. If it is softer than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the other hand, if it is too hard than the above range, the durability to cracking upon repeated impacts may be deteriorated or the feel at impact may become too hard. The thickness of the envelope layer is not particularly limited, but is preferably 1.0 mm or more, more preferably 1.2 mm or more, still more preferably 1.4 mm or more, and the upper limit is preferably 4. It is 0 mm or less, More preferably, it is 3.0 mm or less, More preferably, it is 2.0 mm or less. Outside this range, the low spin effect due to the driver (W # 1) hit may not be sufficient and the flight distance may not be extended.

  The envelope layer in the present invention uses a resin material as a main material. As the resin material for the envelope layer, an ionomer resin is suitable. In particular, zinc-neutralized ionomer resins and sodium-neutralized ionomer resins are more preferable, and one kind can be used alone or two or more kinds can be used in combination. When both are mixed and used, the blending ratio is zinc neutralization type / sodium neutralization type (mass ratio), preferably 25/75 to 75/25, more preferably 35/65 to 65/35, Preferably it is 45 / 55-55 / 45. If it is out of the above range, the rebound will be too low to obtain the desired jump, the crack durability at repeated hits at normal temperature will deteriorate, and the crack durability at low temperature (below zero) may deteriorate. is there. Each ionomer preferably has an acid content of 16% by mass or more, more preferably 17% by mass or more, and still more preferably 18% by mass or more. The blending amount is preferably 20% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. If the acid content and blending amount are insufficient, the low spin effect may be insufficient and a desired flight distance may not be obtained.

The material hardness of the envelope layer is preferably higher than the material hardness of the intermediate layer. As a result, the low spin effect upon hitting the driver (W # 1) can be sufficiently realized. The difference between the material hardness of the envelope layer and the intermediate layer is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and the upper limit is 4 or less. If it deviates from the above range, the low spin effect at the time of hitting the driver (W # 1) may be insufficient and a desired flight distance may not be obtained.

Next, the intermediate layer will be described.
The material hardness of the intermediate layer is not particularly limited, but is preferably durometer D hardness, preferably 50 or more, more preferably 55 or more, still more preferably 60 or more, and the upper limit is preferably 70 or less, more preferably 66 or less, more preferably 63 or less. If it is softer than the above range, the spin distance may be excessively applied during a full shot and the flight distance may not be extended. On the contrary, if it is harder than the above range, the durability to cracking at the time of repeated hitting may be deteriorated, or the hit feeling at the time of carrying out a putter or a short approach may become too hard. The thickness of the intermediate layer is not particularly limited, but is preferably 0.7 mm or more, more preferably 0.9 mm or more, further preferably 1.1 mm or more, and the upper limit is preferably 2. It is 0 mm or less, more preferably 1.7 mm or less, and still more preferably 1.4 mm or less. If it deviates from the range, the low spin effect due to the driver (W # 1) hit may not be sufficient and the flight distance may not be extended. On the other hand, if it is smaller than the above range, the durability against cracking at the time of repeated impacts and the durability at low temperatures may deteriorate.

  The intermediate layer in the present invention is formed mainly using a resin material that is the same or different from the material of the envelope layer described above, and it is particularly preferable to use an ionomer resin. Specific examples include sodium-neutralized ionomer resins such as (trade names) Himiran 1605 and 1601, and Surlyn 8120, and zinc-neutralized ionomer resins such as Himiran 1557, 1706, and 1855. Species can be used alone or in combination of two or more.

  Particularly preferable as the material for the intermediate layer is an embodiment in which a zinc neutralized ionomer resin and a sodium neutralized ionomer resin are mixed and used as a main material in order to achieve the object of the present invention. The blending ratio of zinc neutralization type / sodium neutralization type (mass ratio) is preferably 25/75 to 75/25, more preferably 35/65 to 65/35, still more preferably 45/55 to 55/45. It is. If it is out of the above range, the rebound will be too low to obtain the desired jump, the crack durability at repeated hits at normal temperature will deteriorate, and the crack durability at low temperature (below zero) may deteriorate. is there.

  About the said intermediate | middle layer material, in order to improve the adhesiveness with the polyurethane used with the cover mentioned later, it is suitable to grind | polish the intermediate | middle layer surface. Furthermore, it is preferable to apply a primer (adhesive) to the surface of the intermediate layer after the polishing treatment, or to add an adhesion reinforcing material in the material. Examples of the adhesion reinforcing material blended in the material include organic compounds such as 1,3-butanediol and trimethylolpropane, and oligomers such as polyethylene glycol and polyhydroxy polyolefin oligomer. In particular, trimethylolpropane and polyhydroxy polyolefin oligomer are preferably used. As these commercial products, for example, trimethylolpropane manufactured by Mitsubishi Gas Chemical Co., Ltd., polyhydroxypolyolefin oligomer manufactured by Mitsubishi Chemical Co., Ltd. (the main chain has 150 to 200 carbon atoms, and has a hydroxyl group at the end. Trade name Polytail H), etc. Can be mentioned.

  Next, the cover will be described. The cover referred to in the present invention means the outermost layer in the ball structure, and the intermediate layer and the envelope layer referred to in the present invention are excluded.

  The material hardness of the cover is not particularly limited, but is preferably durometer D hardness of 30 or more, more preferably 40 or more, still more preferably 45 or more, and the upper limit is preferably 55 or less. More preferably, it is 54 or less, More preferably, it is 53 or less. If it is smaller than the above range, the spin distance may not be extended due to excessive spin during full shot. On the other hand, if the range is larger than the above range, there is a possibility that professionals and advanced players do not have sufficient controllability without taking spin in the approach.

  Although there is no restriction | limiting in particular in the thickness of a cover, It is suitable to set it as 0.3 mm or more, More preferably, it is 0.5 mm or more, More preferably, it is 0.7 mm or more. As an upper limit, Preferably it is 1.5 mm or less, More preferably, it is 1.3 mm or less, More preferably, it is 1.1 mm or less. If it is thicker than the above range, the rebound of the ball may be insufficient when it is hit by the driver (W # 1), or the spin amount may increase, resulting in an increase in flight distance. On the other hand, if it is thinner than the above range, the scratch resistance may be deteriorated, or the controllability may be insufficient even for professionals and advanced players.

The cover material is preferably made of polyurethane as a main material from the viewpoint of controllability and scratch resistance, and among them, a thermoplastic urethane cover is particularly preferably used from the viewpoint of mass productivity. Moreover, in this invention, it is suitably employ | adopted as employ | adopting the cover molding material (C) which has the following (A) and (B) component as a main component.
(A) Thermoplastic polyurethane material (B) A thermoplastic resin (b-2) that does not substantially react with isocyanate with an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule. ) Isocyanate mixture dispersed in

Hereinafter, components (A), (B) and (C) will be described.
(A) Thermoplastic polyurethane material The thermoplastic polyurethane material has a soft segment composed of a polymer polyol (polymeric glycol), a chain extender constituting a hard segment, and a diisocyanate. Here, as the raw material polymer polyol, any of those conventionally used in the technology relating to thermoplastic polyurethane materials can be used, and is not particularly limited. The polyether type is preferable to the polyester type in that a thermoplastic polyurethane material having a high elastic modulus and excellent low-temperature characteristics can be synthesized. Examples of the polyether polyol include polytetramethylene glycol and polypropylene glycol. Polytetramethylene glycol is particularly preferable from the viewpoint of the resilience modulus and low temperature characteristics. The average molecular weight of the polymer polyol is preferably 1000 to 5000, and particularly preferably 2000 to 4000 in order to synthesize a thermoplastic polyurethane material having high resilience.

  As the chain extender, those used in the conventional technology relating to thermoplastic polyurethane materials can be suitably used. For example, 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1 , 6-hexanediol, 2,2-dimethyl-1,3-propanediol and the like, but are not limited thereto. These chain extenders preferably have an average molecular weight of 20 to 15000.

  As the diisocyanate, those used in the conventional technology relating to thermoplastic polyurethane materials can be suitably used. For example, aromatics such as 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate can be used. Aliphatic diisocyanates, aliphatic diisocyanates such as hexamethylene diisocyanate, and the like, but are not limited thereto. However, some isocyanate species make it difficult to control the crosslinking reaction during injection molding. In the present invention, 4,4'-diphenylmethane diisocyanate, which is an aromatic diisocyanate, is most preferred from the viewpoint of stability of reactivity with the isocyanate mixture (B) described later.

  As the thermoplastic polyurethane material, commercially available products can be suitably used. For example, Pandex T-8290, T-8295, T-8260 manufactured by DIC Bayer Polymer Co., Ltd., and Dainichi Seika Kogyo Co., Ltd. Resamine 2593, 2597 and the like can be mentioned.

(B) Isocyanate mixture Isocyanate mixture (B) is a thermoplastic resin (b-2) that does not substantially react with isocyanate with an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule. ). Here, as said isocyanate compound (b-1), what is used in the technique regarding the conventional thermoplastic polyurethane material can be used suitably, for example, 4,4'- diphenylmethane diisocyanate, 2, 4-toluene diisocyanate. , Aromatic diisocyanates such as 2,6-toluene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, but are not limited thereto. However, 4,4′-diphenylmethane diisocyanate is optimal in terms of reactivity and work safety.

  The thermoplastic resin (b-2) is preferably a resin having low water absorption and excellent compatibility with the thermoplastic polyurethane material. Examples of such resins include polystyrene resins, polyvinyl chloride resins, ABS resins, polycarbonate resins, and polyester elastomers (polyether / ester block copolymers, polyester / ester block copolymers, etc.). From the viewpoint of strength, a polyester elastomer, particularly a polyether / ester block copolymer is particularly preferable.

  The blending ratio of the thermoplastic resin (b-2): isocyanate compound (b-1) in the isocyanate mixture (B) is preferably 100: 5 to 100: 100, more preferably 100: 10 to 100: 40 in terms of mass ratio. It is preferable that When the blending amount of the isocyanate compound (b-1) with respect to the thermoplastic resin (b-2) is too small, in order to obtain a sufficient addition amount for the crosslinking reaction with the thermoplastic polyurethane material (A), a larger amount of the isocyanate mixture (B) must be added, and the physical properties of the cover molding material (C) become insufficient due to the great influence of the thermoplastic resin (b-2). When the amount of the isocyanate compound (b-1) is too large relative to the thermoplastic resin (b-2), the isocyanate compound (b-1) causes a slip phenomenon during kneading, and it is difficult to synthesize the isocyanate mixture (B). It becomes.

  The isocyanate mixture (B) is prepared by, for example, blending the isocyanate compound (b-1) with the thermoplastic resin (b-2), and kneading them sufficiently with a mixing roll or Banbury mixer at a temperature of 130 to 250 ° C. Or by cooling after cooling. A commercially available product can be suitably used as the isocyanate mixture (B), and examples thereof include Crossnate EM30 manufactured by Dainichi Seika Kogyo Co., Ltd.

(C) Cover molding material The cover molding material (C) is mainly composed of the thermoplastic polyurethane material (A) and the isocyanate mixture (B) described above. The blending ratio of the thermoplastic polyurethane material (A): isocyanate mixture (B) in the cover molding material (C) is preferably 100: 1 to 100: 100, more preferably 100: 5 to 100: 50, in particular, by mass ratio. It is preferable that it is 100: 10-100: 30. If the blending amount of the isocyanate mixture (B) with respect to the thermoplastic polyurethane material (A) is too small, the crosslinking effect is not sufficiently exhibited, and if it is too large, the unreacted isocyanate causes a coloring phenomenon in the molded product.

  In addition to the components described above, other components can be blended in the cover molding material (C). Examples of such other components include thermoplastic polymer materials other than thermoplastic polyurethane materials. For example, polyester elastomers, polyamide elastomers, ionomer resins, styrene block elastomers, polyethylene, nylon resins and the like can be blended. it can. In this case, the blending amount of the thermoplastic polymer material other than the thermoplastic polyurethane material is preferably 0 to 100 parts by mass, more preferably 1 to 75 parts by mass with respect to 100 parts by mass of the thermoplastic polyurethane material which is an essential component. More preferably, it is 10-50 mass parts, and it is suitably selected according to adjustment of the hardness of a cover material, improvement of resilience, improvement of fluidity, improvement of adhesiveness, etc. Furthermore, the cover molding material (C) can be blended with various additives as necessary. For example, pigments, dispersants, antioxidants, light stabilizers, ultraviolet absorbers, and release agents are blended as appropriate. can do.

  In the molding of the cover using the cover molding material (C), for example, the isocyanate mixture (B) is added to the thermoplastic polyurethane material (A) and dry-mixed, and this mixture is used around the core by an injection molding machine. The cover can be molded. The molding temperature varies depending on the type of the thermoplastic polyurethane material (A), but is preferably in the range of 150 to 250 ° C.

  As a reaction form and a crosslinked form of the golf ball cover obtained as described above, an isocyanate group reacts with a residual OH group of a thermoplastic polyurethane material to form a urethane bond, or a urethane group of a thermoplastic polyurethane material. It is considered that an addition reaction of an isocyanate group occurs to form an allophanate or burette crosslinked form. In this case, the cross-linking reaction does not proceed sufficiently immediately after the injection molding of the cover molding material (C), but the cross-linking reaction proceeds by performing annealing after molding, and retains useful characteristics as a golf ball cover. . Annealing means that the cover is aged by heating at a constant temperature for a certain period of time, or aged for a certain period at room temperature.

  In addition to the resin component, various additives can be blended in the resin material of the envelope layer, the intermediate layer, and the cover as described above, if necessary. Examples of such additives include pigments, dispersants, antioxidants, UV absorbers, UV stabilizers, mold release agents, plasticizers, inorganic fillers (such as zinc oxide, barium sulfate, and titanium dioxide). be able to.

Relationship between core surface hardness, envelope layer, intermediate layer and cover material hardness In the present invention, the relationship between the core surface hardness, envelope layer, intermediate layer and cover material hardness is durometer D hardness, cover material hardness <intermediate Layer material hardness <enveloping layer material hardness> It is necessary to satisfy the condition of core surface hardness. The reason is as described above in the description of the envelope layer.

Relationship between the thicknesses of the envelope layer, the intermediate layer, and the cover In the present invention, the thicknesses of the envelope layer, the intermediate layer, and the cover satisfy the condition of cover thickness <interlayer thickness <envelop layer thickness. is necessary. By achieving a ball structure with a core diameter of 31 mm or more and designing the ball structure as described above in relation to the thickness of the envelope layer, the intermediate layer, and the cover, a ball that achieves both flying, controllability and feel is achieved. Can do. In this case, if the cover is thicker than the intermediate layer, the ball repulsion may become low, or the spin may be excessively applied during a full shot and the flight distance may not be extended. On the other hand, if the envelope layer is thinner than the intermediate layer, the low spin effect may not be sufficient, and the target flight distance may not be obtained.

  A method for producing a multi-piece solid golf ball that is formed by laminating the core, envelope layer, intermediate layer, and cover described above can be performed by a conventional method such as a known injection molding method. For example, a vulcanized molded product mainly composed of a rubber material is disposed in a predetermined injection mold as a core, and in order, an envelope layer material and an intermediate layer material are injected to obtain an intermediate spherical body, A multi-piece golf ball can be obtained by arranging the spherical body in another injection mold and injection molding the cover material. Further, the cover can be laminated by a method of covering the cover with an intermediate spherical body. For example, the intermediate spherical body can be wrapped in two half cups that have been previously formed into a half-shell spherical shape and heat-pressed. .

  In addition, a large number of dimples can be formed on the cover surface. The dimples arranged on the cover surface are not particularly limited, but are preferably 280 or more, more preferably 300 or more, still more preferably 320 or more, and the upper limit is preferably 360 or less, more Preferably 350 or less, more preferably 340 or less can be provided. If the number of dimples exceeds the above range, the trajectory of the ball may be lowered and the flight distance may be reduced. Conversely, when the number of dimples decreases, the trajectory of the ball increases and the flight distance may not increase.

  About the shape of a dimple, it can use suitably combining 1 type or 2 types or more, such as circular, various polygons, a dew drop shape, and other ellipses. For example, when circular dimples are used, the diameter is preferably about 2.5 mm to 6.5 mm, and the depth is preferably 0.08 mm to 0.30 mm.

The dimple occupancy ratio that the dimples occupy on the spherical surface of the golf ball, specifically, the sum of the dimple areas defined by the surface edges of the plane surrounded by the edges of the dimples occupies the ball sphere area assuming that no dimples exist About a ratio (SR value), it is desirable that it is 60% or more and 90% or less from the point which can fully exhibit aerodynamic characteristics. Further, a value V _{0 obtained} by dividing the space volume of the dimple below the plane surrounded by the edge of each dimple by the volume of the cylinder having the plane as the bottom and the maximum depth of the dimple from the bottom as a height is: From the viewpoint of optimizing the ball trajectory, it is set to 0.35 or more and 0.80 or less . Further, the VR value occupying the ball-ball volume assuming that the total dimple volume formed below the plane surrounded by the dimple edges does not exist is 0.6% to 1.0% . If the value deviates from the above ranges, the trajectory may not provide a good flight distance, and a sufficiently satisfactory flight distance may not be obtained.

  The golf ball of the present invention can be used for competition and comply with golf regulations. The ball outer diameter is 42.80 mm or less and does not pass through a ring with an inner diameter of 42.672 mm, and the weight is usually 45. 0.04 to 45.93 g.

  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 and 2 and Comparative Examples 1 to 6]
Formation of Core After adjusting the rubber composition by the formulation shown in Table 1, a core was prepared by vulcanization molding under the vulcanization conditions in the table. The number of the compounding amount in the following table | surface shows a mass part.

In addition, the brand name of the main material described in the table | surface is as follows.
Polybutadiene: BR730 manufactured by JSR (Nd-based catalyst)
Peroxide (1): Dicumyl peroxide, product name Park Mill D, manufactured by NOF Corporation
Peroxide (2): 1,1-di (t-butylperoxy) cyclohexane manufactured by NOF Corporation
Silica mixture Perhexa C-40
Anti-aging agent: 2,2-methylenebis (4-methyl-6-butyl) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Phenol) NOCRACK NS-6
Sulfur: Zinc flower mixed sulfur manufactured by Tsurumi Chemical Co., Ltd.

Formation of envelope layer, intermediate layer, and cover Next, the envelope layer, intermediate layer, and cover containing various resin components shown in Table 2 were molded by injection molding, and the envelope layer, intermediate layer around the core The cover was sequentially coated and formed. Then, using the common dimples shown in Table 3, a multi-piece solid golf ball having the dimples formed on the cover surface was produced.

※ 上記表中の数字は質量部で表される。

* The numbers in the above table are expressed in parts by mass.

In addition, the trade names of main materials described in Table 2 are as follows.
High Milan: Ionomer resin AM7317 manufactured by Mitsui DuPont Polychemical Co., Ltd .: Mitsui DuPont Polychemical high rigidity ionomer resin Acid content 18%
Zn-based ionomer AM7318: Mitsui DuPont polychemical high-rigidity ionomer resin with an acid content of 18%
Na-based ionomer AM7311: Ionomer resin dynalon manufactured by Mitsui DuPont Polychemical Co., Ltd. Hydrogenated polymer Hytrel manufactured by JSR Co., Ltd. Polyester elastomer behenic acid manufactured by NOF Corporation NAA222-S bead-designated calcium hydroxide: Shiroishi CLS-B designated trimethylol propane manufactured by Kogyo Co., Ltd .: Trimethylol propane polytail H manufactured by Mitsubishi Gas Chemical Co., Ltd. Low molecular weight polyolefin polyols T8260, T8295 manufactured by Mitsubishi Chemical Co., Ltd. Trademark Pandex manufactured by DIC Bayer Polymer
MDI-PTMG type thermoplastic polyurethane polyethylene wax: Sanyo Kasei Co., Ltd. trade name Sun Wax 161P
Isocyanate compound: Trade name “Crosnate EM30”
4, 4 with isocyanate masterbatch manufactured by Dainichi Seika Kogyo Co., Ltd.
'-Containing 30% diphenylmethane diisocyanate.
Amine back titration isocyanate measurement concentration according to JIS-K1556
5-10%, masterbatch base resin is polyester elastomer
Was used. It should be noted that the isocyanate compound is filtered during injection molding.
Used in combination with Ndex.

Dimples Definition <br/> diameter: diameter depth flat plane circumscribed by an edge of the dimple: maximum depth of the dimple from the plane surrounded by the edge of the dimple V _0: under flat plane circumscribed by an edge of the dimple A value obtained by dividing the spatial volume of the dimple by a cylindrical volume having the plane as the bottom surface and the maximum depth of the dimple from the bottom surface as a height SR: a dimple defined by the surface edge of the plane surrounded by the edge of the dimple The ratio of the total area to the ball sphere area assuming that no dimples exist VR: The total dimple volume formed below the plane surrounded by the edges of the dimples is the ball assuming that no dimples exist Proportion of ball volume

  For each of the obtained golf balls of Examples 1 and 2 and Comparative Examples 1 to 6, the surface hardness and other physical properties, flying performance, approach spin (controllability) and scratch resistance of each layer and ball were evaluated according to the following criteria. did. The results are shown in Table 4. In addition, all measured in 23 degreeC environment.

(1) Deflection amount of core Deflection amount (mm) of the core when the core is placed on a hard plate and loaded from an initial load of 98 N (10 kgf) to a final load of 1275 N (130 kgf).
(2) Core surface hardness The surface of the core is a spherical surface. Set the surface of the hardness meter so that the surface of the core is almost perpendicular to the surface of the core, and use the durometer D hardness (ASTM-2240 standard durometer type D) to The average value of the values measured randomly at two points.
(3) Material Hardness of Enveloping Layer The resin material of the enveloping layer was produced in a sheet shape having a thickness of 2 mm, and measured by a durometer “Type D” of the ASTM-2240 standard.
(4) Intermediate layer material hardness This is the same measurement method as in (3) above.
(5) Cover material hardness This is the same measurement method as in (3) above.
(6) Ball deflection amount Ball deflection amount (mm) when the ball is placed on a hard plate and loaded from an initial load of 98 N (10 kgf) to a final load of 1275 N (130 kgf). However, only Example 1 and Example 2 were measured.
(7) Flying club (W # 1) (made by Bridgestone Sports, “TourStage X-Drive Type 405” (loft angle 9.5 °) was mounted on the striking robot and hit at a head speed (HS) of 45 m / s. The carry distance and total flight distance of the hour were measured, and the following criteria were used for the evaluation: The spin amount was a value obtained by measuring the ball immediately after hitting with an initial condition measuring device.
○: Total flight distance of 232.0m or more
×: Total flight distance less than 232.0m
(8) Approach spin amount Sand wedge (SW) (manufactured by Bridgestone Sports Co., Ltd., J's Classical Edition) was used to measure the spin amount when hit at HS 22 m / s. The following criteria were used for the evaluation. The spin amount was measured by the same method as the above flight distance measurement.
○: Spin amount is 6600 rpm or more
Δ: Spin amount is 6300 rpm or more and less than 6600 rpm
X: Spin amount is less than 6300 rpm
(9) 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.
Y: Can still be used
×: Cannot be used anymore

＊１ 実施例について、ボールのたわみ量を計測した結果、実施例１が２．２ｍｍ、実施例２が２．４ｍｍであった。

* 1 About Example, as a result of measuring the amount of deflection of the ball, Example 1 was 2.2 mm and Example 2 was 2.4 mm.

From the results of Table 4, the golf balls of Comparative Examples 1 to 6 are inferior in the following respects as compared with the present invention (Examples).
In Comparative Example 1, since the cover was made of an ionomer resin, the scuff resistance was low and the approach was difficult to spin.
In Comparative Example 2, since the core diameter was less than 31 mm, the spin amount increased when the driver (W # 1) was hit, and the flight distance did not increase.
In Comparative Example 3, since the cover layer was thicker than the intermediate layer, the spin amount increased when the driver (W # 1) was hit, and the flight distance did not increase.
In Comparative Example 4, since the envelope layer was softer than the intermediate layer, the spin amount increased when the driver (W # 1) was hit, and the flight distance did not increase.
In Comparative Example 5, since the cover layer was harder than the intermediate layer, the scratch resistance was inferior and the spin amount at the time of approach was insufficient.
Comparative Example 6 is a three-piece golf ball in which a core having no envelope layer is coated with two layers. This ball still has a large amount of spin and does not extend its flight distance.

It is a schematic sectional drawing of the multi-piece solid golf ball (four-layer structure) of this invention. It is a top view of the golf ball showing the arrangement mode of the dimples used in this example.

Explanation of symbols

1 Core 2 Enveloping Layer 3 Intermediate Layer 4 Cover G Golf Ball D Dimple

Claims (5)

A multi-piece solid golf ball comprising a core, an envelope layer covering the core, an intermediate layer covering the core, and a cover covering the core and having a plurality of dimples formed on the surface. The material has a core diameter of 31 mm or more, the envelope layer and the intermediate layer are each made of the same or different resin material, and the cover is made of polyurethane. And the thickness of the envelope layer, intermediate layer and cover is as follows:
Satisfying the relationship of cover thickness <interlayer thickness <envelopment layer thickness, and the surface hardness (durometer D hardness) of the core and the material hardness (durometer D hardness) of the envelope layer, intermediate layer and cover are as follows. ,
Cover material hardness <Intermediate layer material hardness <Enveloping layer material hardness> Core surface hardness
The value obtained by subtracting the core surface hardness from the envelope layer material hardness is 18 to 25, the value obtained by subtracting the intermediate layer material hardness from the envelope layer material hardness is 1 to 4, and A value V _{0 obtained} by dividing the space volume of the dimple below the plane surrounded by the edge of the dimple by a cylindrical volume having the plane as the bottom surface and the maximum depth of the dimple from the bottom surface as a height is 0.35 or more 0 The VR value occupying the ball ball volume assuming that the dimple volume formed below the plane surrounded by the dimple edges is not present is 0.6% or more and 1.0 or less. % Multi-piece solid golf ball characterized by The resin component for forming the surrounding layer, multi-piece solid golf ball of claim 1, wherein the acid content comprising 16 wt% or more ionomer resins. The resin component forming the cover is
(A) a thermoplastic polyurethane material;
(B) An isocyanate masterbatch in which an isocyanate compound (b-1) having two or more isocyanate groups as functional groups in one molecule is dispersed in a thermoplastic resin (b-2) that does not substantially react with isocyanate. the multi-piece solid golf ball of claim 1 or 2, wherein the main component an isocyanate mixture comprising and. The material hardness (durometer D hardness) of the envelope layer, intermediate layer and cover is
60 ≦ enveloping layer material hardness ≦ 70,
55 ≦ interlayer material hardness ≦ 70,
30 ≤ Cover material hardness ≤ 55
The multi-piece solid golf ball according to any one of claims 1 to 3 . In the golf ball, the deflection amount (mm) from when the initial load 98N (10 kgf) to the final load 1275N (130 kgf) is applied to the ball and the core is 2.0 mm ≦ ball deflection amount ≦ 3, respectively. 0mm,
3.5mm ≦ Core deflection ≦ 6.0mm
The multi-piece solid golf ball according to any one of claims 1 to 4 .

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