US20200179767A1 - Multi-piece solid golf ball - Google Patents

Multi-piece solid golf ball Download PDF

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Publication number
US20200179767A1
US20200179767A1 US16/690,240 US201916690240A US2020179767A1 US 20200179767 A1 US20200179767 A1 US 20200179767A1 US 201916690240 A US201916690240 A US 201916690240A US 2020179767 A1 US2020179767 A1 US 2020179767A1
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Prior art keywords
hardness
core
surface area
layer
envelope layer
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US16/690,240
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Inventor
Hideo Watanabe
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Bridgestone Sports Co Ltd
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Bridgestone Sports Co Ltd
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Assigned to BRIDGESTONE SPORTS CO., LTD. reassignment BRIDGESTONE SPORTS CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: WATANABE, HIDEO
Publication of US20200179767A1 publication Critical patent/US20200179767A1/en
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    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/007—Characteristics of the ball as a whole
    • A63B37/0072—Characteristics of the ball as a whole with a specified number of layers
    • A63B37/0076—Multi-piece balls, i.e. having two or more intermediate layers
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/0022—Coatings, e.g. paint films; Markings
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/0022—Coatings, e.g. paint films; Markings
    • A63B37/00222—Physical properties, e.g. hardness
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/007—Characteristics of the ball as a whole
    • A63B37/0077—Physical properties
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/007—Characteristics of the ball as a whole
    • A63B37/0077—Physical properties
    • A63B37/0092—Hardness distribution amongst different ball layers
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2102/00—Application of clubs, bats, rackets or the like to the sporting activity ; particular sports involving the use of balls and clubs, bats, rackets, or the like
    • A63B2102/32—Golf
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/0023—Covers
    • A63B37/0029—Physical properties
    • A63B37/0033—Thickness
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B37/00—Solid balls; Rigid hollow balls; Marbles
    • A63B37/0003—Golf balls
    • A63B37/0038—Intermediate layers, e.g. inner cover, outer core, mantle
    • A63B37/004—Physical properties
    • A63B37/0045—Thickness

Definitions

  • the present invention relates to a multi-piece solid golf ball having five or more layers, including a core, an inner envelope layer, an outer envelope layer, an intermediate layer and a cover.
  • the ball Furthermore, there exists a desire for the ball to have durability to repeated impact and for scuffing observed on the ball surface when a golf ball is repeatedly hit with different clubs to be suppressed (increased scuff resistance), maximal protection of the ball from external factors also being an important topic in golf ball development.
  • art relating to golf balls having a five-layer construction consisting of a core encased by four layers—an inner envelope layer, an outer envelope layer, an intermediate layer and a cover (outermost layer)—in which the ball construction is internally varied among the plurality of layers such that the core surface hardness ⁇ inner envelope layer hardness ⁇ outer envelope layer hardness ⁇ intermediate layer hardness >cover hardness is described in, for example, U.S. Pat. Nos. 7,749,108, 7,445,567, 7,637,826 and 8,371,960.
  • Other golf balls having five or more layers are described in, for example, U.S. Pat. Nos. 8,357,060 and 8,979,677.
  • the spin rate of the ball on shots with a driver (W#1) is suppressed and a high initial velocity on shots can be obtained, enabling a good distance to be achieved.
  • the spin rate on approach shots in the short game is optimized, increasing the ball controllability.
  • the ball has a good feel that is not too hard.
  • the golf ball of the invention by being able to hold down the spin rate of the ball on shots with a driver (W#1) and by having a high initial velocity on shots, is able to achieve a good distance.
  • a driver W#1
  • the ball tends to have too hard at feel at impact.
  • the ball by giving the golf ball a multilayer structure and specifying the surface hardnesses of the respective layer-encased spheres therein, the ball can be endowed with both a good distance and a good feel, making the ball ideally suited for professional golfers and skilled to amateurs.
  • it is preferable to use as the outermost layer material a urethane resin material having flexibility and a high durability.
  • the invention provides a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, wherein the core is formed primarily of a base rubber; the envelope layer, intermediate layer and cover are each formed of a resin material; the envelope layer is formed into two layers-an inner layer and an outer layer; and the core has a center hardness and a surface hardness, the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) has a surface hardness and the ball has a surface hardness which together satisfy the following relationship:
  • the core has a hardness profile in which, letting Cc be the Shore C hardness at the core center, Cs be the Shore C hardness at the core surface, C M be the Shore C hardness at a midpoint M between the center and the surface of the core, C M+2.5 .
  • C M+5.0 and C M+0.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core surface side and C M ⁇ 2
  • C M ⁇ 5.0 and C M ⁇ 7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core center side, the following surface areas A to F:
  • surface areas A to E in the core hardness profile may satisfy the condition
  • surface areas A to F in the core hardness profile may satisfy the condition
  • surface areas B to E in the core hardness profile may satisfy the condition
  • the envelope layer has a thickness which satisfies the condition
  • the thicknesses of the outer envelope layer and the intermediate layer satisfy the condition
  • the thicknesses of the envelope layer, the intermediate layer and the cover satisfy the condition
  • a coating layer is formed on a surface of the cover, which coating layer has a Shore C hardness of from 40 to 80.
  • the difference C M ⁇ Hc may be at least ⁇ 10 and up to 10.
  • the invention provides a multi-piece solid golf ball having a core, an inner envelope layer, an outer envelope layer, an intermediate layer and a cover, wherein the core has a surface hardness, the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) has a surface hardness and the ball has a surface hardness which together satisfy the following relationship:
  • the core has a hardness profile in which, letting Cc be the Shore C hardness at the core center, Cs be the Shore C hardness at the core surface, C M be the Shore C hardness at a midpoint M between the center and the surface of the core, C M+2.5 , C M+5.0 and C M+7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core surface side and C M ⁇ 2.5 , C M ⁇ 5.0 and C M ⁇ 7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core surface side, the following surface areas A to F:
  • surface areas A to F in the core hardness profile satisfy the condition
  • a coating layer is formed on a surface of the cover and, letting He be the Shore C hardness of the coating layer and letting Chi be the Shore C hardness at the midpoint M between the center and surface of the core, the difference C M ⁇ Hc is at least ⁇ 10 and up to 10.
  • the multi-piece solid golf ball of the invention has a lowered spin rate on full shots with a driver, enabling the distance of the ball to be further increased, and also has a good controllability on approach shots. In addition, the feel at impact is good and the scuff resistance is excellent. Such qualities make this ball highly useful as a golf ball for professional golfers and skilled amateurs.
  • FIG. 1 is a schematic cross-sectional view of the multi-piece solid golf ball (5-layer structure) according to the invention.
  • FIG. 2 is a graph that uses core hardness profile data from Example 1 to explain surface areas A to F in the core hardness profile.
  • the multi-piece solid golf ball of the invention is, as shown in FIG. 1 , a multilayer golf ball G having four or more layers that include a core 1 , an inner envelope layer 2 a and outer envelope layer 2 b encasing the core 1 , an intermediate layer 3 encasing the envelope layers, and a cover 4 encasing the intermediate layer 3 .
  • Numerous dimples D are typically formed on the surface of the cover 4 .
  • a coating layer is generally coated onto the surface of the cover 4 . Excluding the coating layer, the cover 4 is positioned as the outermost layer in the layered structure of the golf ball.
  • the core 1 , intermediate layer 3 and cover 4 are each not limited to a single layer and may be formed of a plurality of two or more layers.
  • the core has a diameter which, although not particularly limited, is preferably at least 30.0 mm, more preferably at least 31.0 mm, and even more preferably at least 31.5 mm.
  • the core diameter is preferably not more than 35.0 mm, more preferably not more than 34.0 mm, and even more preferably not more than 33.5 mm.
  • the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) which, although not particularly limited, is preferably at least 3.0 mm, more preferably at least 3.5 mm, and even more preferably at least 4.0 mm.
  • the core deflection is preferably not more than 7.0 mm, more preferably not more than 6.0 mm, and even more preferably not more than 5.0 mm.
  • the spin rate of the ball may rise excessively, possibly resulting in a poor distance, or the feel at impact may be too hard.
  • the core deflection is too large, i.e., when the core is too soft, the ball rebound may be too low, resulting in a poor distance, the feel at impact may be too soft, or the durability to cracking on repeated impact may worsen.
  • the core material is made primarily of a rubber material.
  • a rubber composition can be prepared using a base rubber as the primary component and blending with this other ingredients such as co-crosslinking agents, organic peroxides, inert fillers and organosulfur compounds. It is preferable to use polybutadiene as the base rubber.
  • polystyrene-butadiene rubbers examples include BR01, BR51 and BR730 (all products of JSR Corporation).
  • the proportion of polybutadiene within the base rubber is preferably at least 60 wt %, and more preferably at least 80 wt %.
  • Rubber ingredients other than the above polybutadienes may be included in the base rubber, provided that doing so does not detract from the advantageous effects of the invention.
  • rubber ingredients other than the above polybutadienes include other polybutadienes and also other diene rubbers, such as styrene-butadiene rubbers, natural rubbers, isoprene rubbers and ethylene-propylene-diene rubbers.
  • co-crosslinking agents examples include unsaturated carboxylic acids and metal salts of unsaturated carboxylic acids.
  • unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid and fumaric acid. The use of acrylic acid or methacrylic acid is especially preferred.
  • Metal salts of unsaturated carboxylic acids are exemplified by, without particular limitation, the above unsaturated carboxylic acids that have been neutralized with desired metal ions.
  • Specific examples include the zinc salts and magnesium salts of methacrylic acid and acrylic acid. The use of zinc acrylate is especially preferred.
  • the unsaturated carboxylic acid and/or metal salt thereof is included in an amount, per 100 parts by weight of the base rubber, which is typically at least 5 parts by weight, preferably at least 9 parts by weight, and more preferably at least 13 parts by weight.
  • the amount included is typically not more than 60 parts by weight, preferably not more than 50 parts by weight, and more preferably not more than 40 parts by weight. Too much may make the core too hard, giving the ball an unpleasant feel at impact, whereas too little may lower the rebound.
  • the organic peroxide may be used as the organic peroxide.
  • examples of such products that may be suitably used include Percumyl D, Perhexa C-40 and Perhexa 3M (all from NOF Corporation), and Luperco 231XL (from AtoChem Co.). One of these may be used alone, or two or more may be used together.
  • the amount of organic peroxide included per 100 parts by weight of the base rubber is preferably at least 0.1 part by weight, more preferably at least 0.3 part by weight, even more preferably at least 0.5 part by weight, and most preferably at least 0.6 part by weight.
  • the upper limit is preferably not more than 5 parts by weight, more preferably not more than 4 parts by weight, even more preferably not more than 3 parts by weight, and most preferably not more than 2.5 parts by weight. When too much or too little is included, it may not be possible to obtain a ball having a good feel, durability and rebound.
  • Another compounding ingredient typically included with the base rubber is an inert filler, preferred examples of which include zinc oxide, barium sulfate and calcium carbonate. One of these may be used alone, or two or more may be used together.
  • the amount of inert filler included per 100 parts by weight of the base rubber is preferably at least 1 part by weight, and more preferably at least 5 parts by weight.
  • the upper limit is preferably not more than 50 parts by weight, more preferably not more than 40 parts by weight, and even more preferably not more than 36 parts by weight. Too much or too little inert filler may make it impossible to obtain a proper weight and a suitable rebound.
  • an antioxidant may be optionally included.
  • suitable commercial antioxidants include Nocrac NS-6 and Nocrac NS-30 (both available from Ouchi Shinko Chemical Industry Co., Ltd.), and Yoshinox 425 (available from Yoshitomi Pharmaceutical Industries, Ltd.). One of these may be used alone, or two or more may be used together.
  • the amount of antioxidant included per 100 parts by weight of the base rubber is set to 0 part by weight or more, preferably at least 0.05 part by weight, and more preferably at least 0.1 part by weight.
  • the upper limit is set to preferably not more than 3 parts by weight, more preferably not more than 2 parts by weight, even more preferably not more than 1 part by weight, and most preferably not more than 0.5 part by weight. Too much or too little antioxidant may make it impossible to achieve a suitable ball rebound and durability.
  • organosulfur compound may be included in the core in order to impart a good resilience.
  • the organosulfur compound is not particularly limited, provided it can enhance the rebound of the golf ball.
  • Exemplary organosulfur compounds include thiophenols, thionaphthols, halogenated thiophenols, and metal salts of these.
  • pentachlorothiophenol pentafluorothiophenol, pentabromothiophenol, p-chlorothiophenol
  • the zinc salt of pentachlorothiophenol the zinc salt of pentafluorothiophenol, the zinc salt of pentabromothiophenol, the zinc salt of p-chlorothiophenol
  • any of the following having 2 to 4 sulfur atoms diphenylpolysulfides, dibenzvlpolysulfides, dibenzoylpolysulfides, dibenzothiazoylpolysulfides and dithiobenzoylpolysulfides.
  • the zinc salt of pentachlorothiophenol is especially preferred.
  • the amount of organosulfur compound included per 100 parts by weight of the base rubber is 0 part by weight or more, and it is recommended that the amount be preferably at least 0.05 part by weight, and even more preferably at least 0.1 part by weight, and that the upper limit be preferably not more than 5 parts by weight, more preferably not more than 3 parts by weight, and even more preferably not more than 2.5 parts by weight. Including too much organosulfur compound may make a greater rebound-improving effect (particularly on shots with a W#1) unlikely to be obtained, may make the core too soft or may worsen the feel of the ball at impact. On the other hand, including too little may make a rebound-improving effect unlikely.
  • Decomposition of the organic peroxide within the core formulation can be promoted by the direct addition of water (or a water-containing material) to the core material.
  • the decomposition efficiency of the organic peroxide within the core-forming rubber composition is known to change with temperature, starting at a given temperature, the decomposition efficiency rises with increasing temperature. If the temperature is too high, the amount of decomposed radicals rises excessively, leading to recombination between radicals and, ultimately, deactivation. As a result, fewer radicals act effectively in crosslinking.
  • the water included in the core material is not particularly limited, and may be distilled water or tap water. The use of distilled water that is free of impurities is especially preferred.
  • the amount of water included per 100 parts by weight of the base rubber is preferably at least 0.1 part by weight, and more preferably at least 0.3 part by weight.
  • the upper limit is preferably not more than 5 parts by weight, and more preferably not more than 4 parts by weight.
  • the core can be produced by vulcanizing and curing the rubber composition containing the above ingredients.
  • the core can be produced by using a Banbury mixer, roll mill or other mixing apparatus to intensively mix the rubber composition, subsequently compression molding or injection molding the mixture in a core mold, and curing the resulting molded body by suitably heating it under conditions sufficient to allow the organic peroxide or co-crosslinking agent to act, such as at a temperature of between 100 and 200° C., preferably between 140 and 180° C., for 10 to 40 minutes.
  • the core may consist of a single layer alone, or may be formed as a two-layer core consisting of an inner core layer and an outer core layer.
  • the inner core layer and outer core layer materials may each be composed primarily of the above-described to rubber material.
  • the rubber material making up the outer core layer encasing the inner core layer may be the same as or different from the inner core layer material. The details here are the same as those given above for the ingredients of the core-forming rubber material.
  • the core hardness profile is described.
  • the core hardness refers to the Shore C hardness.
  • This Shore C hardness is a hardness value measured with a Shore C durometer in general accordance with ASTM D2240.
  • the core has a center hardness (Cc) which is preferably at least 50, more preferably at least 52, and even more preferably at least 54.
  • the upper limit is preferably not more than 59, more preferably not more than 57, and even more preferably not more than 55.
  • this value is too large, the feel at impact may harden, or the spin rate on full shots may rise, as a result of which the intended distance may not be achieved.
  • this value is too small, the rebound may become lower and so a good distance may not be obtained, or the durability to cracking under repeated impact may worsen.
  • the core has a surface hardness (Cs) which is preferably at least 73, more preferably at least 75, and even more preferably at least 77.
  • the upper limit is preferably not more than 85, more preferably not more than 83, and even more preferably not more than 81.
  • a core surface hardness outside of this range may lead to undesirable results similar to those described above for the core center hardness (Cc).
  • the difference between the core surface hardness (Cs) and the core center hardness (Cc) is preferably at least 20, more preferably at least 22, and even more preferably at least 24.
  • the upper limit is preferably not more than 35, more preferably not more than 32, and even more preferably not more than 28.
  • this value is too small, the ball spin rate-lowering effect on shots with a driver may be inadequate, resulting in a poor distance.
  • this value is too large, the initial velocity of the ball when struck may decrease, resulting in a poor distance, or the durability to cracking on repeated impact may worsen.
  • FIG. 2 shows a graph that uses core hardness profile data from Example 1 to explain surface areas A to F.
  • each of surface areas A to F is the surface area of a triangle whose base is the difference between specific distances in the core cross-section and whose height is the difference in hardness between positions at these specific distances.
  • the value of (surface area D+surface area E+surface area F) ⁇ (surface area A+surface area B+surface area C) above is preferably at least 3, more preferably at least 4, and even more preferably at least 6.
  • the upper limit is preferably not more than 20, more preferably not more than 15, and even more preferably not more than 10.
  • the following condition it is preferable for the following condition to be satisfied: 0.15 ⁇ [(surface area D+surface area E+surface area F) ⁇ (surface area A+surface area B+surface area C)]/(Cs ⁇ Cc) ⁇ 0.60.
  • the lower limit value here is preferably at least 0.20, and more preferably at least 0.25.
  • the upper limit value in this formula is preferably not more than 0.50, and more preferably not more than 0.40.
  • W#1 spin rate-lowering effect on shots with a driver
  • this value is too large, the initial velocity of the ball when struck may be low, resulting in a poor distance, or the durability to cracking on repeated impact may worsen.
  • the following condition is preferable for the following condition to be satisfied: ⁇ 2 ⁇ (surface area D+surface area E) ⁇ (surface area A+surface area B+surface area C) ⁇ 8.
  • the lower limit value here is more preferably at least 0, and even more preferably at least 1.
  • the upper limit value is more preferably not more than 6, and even more preferably not more than 4.
  • Surface areas B to E in the core hardness profile preferably satisfy the relationship: surface area B ⁇ surface area C ⁇ surface area D ⁇ surface area E.
  • W#1 spin rate-lowering effect on shots with a driver
  • the envelope layer is formed of two layers: an inner layer and an outer layer. These are referred to as, respectively, the inner envelope layer and the outer envelope layer.
  • the inner envelope layer has a material hardness on the Shore D scale which, although not particularly limited, is preferably at least 46, more preferably at least 48, and even more preferably at least 50.
  • the upper limit is preferably not more than 60, more preferably not more than 58, and even more preferably not more than 56.
  • the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere) has a surface hardness on the Shore D scale which is preferably at least 52, more preferably at least 54, and even more preferably at least 56.
  • the upper limit is preferably not more than 66, more preferably not more than 64, and even more preferably not more than 62.
  • the spin rate of the ball on full shots may rise, as a result of which the intended distance may not be achieved.
  • the material hardness and surface hardness are too high, the feel at impact may become too hard or the durability to cracking on repeated impact may worsen.
  • the inner envelope layer has a thickness which is preferably at least 0.8 mm, more preferably at least 1.0 mm, and even more preferably at least 1.2 mm.
  • the upper limit in the thickness of the inner envelope layer is preferably not more than 1.8 mm, more preferably not more than 1.6 mm, and even more preferably not more than 1.4 mm. When the inner envelope layer thickness falls outside of this range, the spin rate-lowering effect on shots with a driver (W#1) may be inadequate and a good distance may not be achieved.
  • the outer envelope layer has a material hardness on the Shore D scale which, although not particularly limited, is preferably at least 43, more preferably at least 45, and even more preferably at least 47.
  • the upper limit is preferably not more than 54, more preferably not more than 52, and even more preferably not more than 50.
  • the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere) has a surface hardness on the Shore D scale which is preferably at least 49, more preferably at least 51, and even more preferably at least 53.
  • the upper limit is preferably not more than 60, more preferably not more than 58, and even more preferably not more than 56.
  • the spin rate of the ball on full shots may rise, as a result of which the intended distance may not be achieved.
  • the material hardness and surface hardness are too high, the feel at impact may become too hard or the durability to cracking on repeated impact may worsen.
  • the outer envelope layer has a thickness which is preferably at least 0.8 mm, more preferably at least 1.0 mm, and even more preferably at least 1.1 mm.
  • the upper limit in the thickness of the outer envelope layer is preferably not more than 1.7 mm, more preferably not more than 1.5 mm, and even more preferably not more than 1.3 mm. When the outer envelope layer thickness falls outside of this range, the spin rate-lowering effect on shots with a driver (W#1) may be inadequate and a good distance may not be achieved.
  • the materials making up the inner envelope layer and the outer envelope layer are not particularly limited; known resins may be used for this purpose.
  • Examples of preferred materials include resin compositions containing as the essential ingredients:
  • A a base resin of (a-1) an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer mixed with (a-2) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer in a weight ratio between 100:0 and 0:100, and
  • Components A to D in the intermediate layer-forming resin material described in, for example, JP-A 2010-253268 may be advantageously used as above components A to D.
  • the resin materials that form the inner envelope layer and the outer envelope layer may be mutually like or unlike.
  • a non-ionomeric thermoplastic elastomer may be included in the respective materials for the inner envelope layer and the outer envelope layer.
  • the non-ionomeric thermoplastic elastomer is preferably included in an amount of from 0 to 50 parts by weight per 100 parts by weight of the total amount of the base resin.
  • thermoplastic elastomers include polyolefin elastomers (including polyolefins and metallocene polyolefins), polystyrene elastomers, diene polymers, polyacrylate polymers, polyamide elastomers, polyurethane elastomers, polyester elastomers and polyacetals.
  • Optional additives may be suitably included in the above resin materials.
  • pigments, dispersants, antioxidants, ultraviolet absorbers and light stabilizers may be added.
  • the amount added per 100 parts by weight of the overall base resin is preferably at least 0.1 part by weight, and more preferably at least 0.5 part by weight.
  • the upper limit is preferably not more than 10 parts by weight, and more preferably not more than 4 parts by weight.
  • the intermediate layer has a material hardness on the Shore D scale which, although not particularly limited, is preferably at least 60, more preferably at least 63, and even more preferably at least 65.
  • the upper limit is preferably not more than 72, more preferably not more than 70, and even more preferably not more than 68.
  • the surface hardness of the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere), expressed on the Shore D scale, is preferably at least 66, more preferably at least 69, and even more preferably at least 71.
  • the upper limit is preferably not more than 78, more preferably not more than 76, and even more preferably not more than 74.
  • the ball rebound on full shots may be inadequate or the spin rate on full shots may rise excessively, resulting in a poor distance.
  • the material hardness and surface hardness are too high, the durability to cracking on repeated impact may worsen or the feel at impact may end up becoming too hard.
  • the intermediate layer has a thickness of preferably at least 0.8 mm, more preferably at least 1.0 mm, and even more preferably at least 1.1 mm.
  • the upper limit in the intermediate layer thickness is preferably not more than 1.7 mm, more preferably not more than 1.5 mm, and even more preferably not more than 1.3 mm. It is preferable for the intermediate layer to have a greater thickness than the subsequently described cover (outermost layer). When the intermediate layer thickness falls outside of the above range or the intermediate layer is formed so as to be thinner than the cover, the spin rate-lowering effect on shots with a driver (W#1) may be inadequate and a good distance may not be achieved.
  • W#1 driver
  • thermoplastic resins particularly ionomeric resins
  • ionomeric resins that are used as golf ball materials
  • commercial products may be used as the ionomeric resin.
  • the intermediate layer-forming resin material that is used may be one obtained by blending, of commercially available ionomeric resins, a high-acid ionomeric resin having an acid content of at least 16 wt % into a conventional ionomeric resin.
  • W#1 driver
  • the amount of unsaturated carboxylic acid included in the high-acid ionomeric resin is typically at least 16 wt %, preferably at least 17 wt %, and more preferably at least 18 wt %.
  • the upper limit is preferably not more than 22 wt %, more preferably not more than 21 wt %, and even more preferably not more than 20 wt %.
  • the amount of high-acid ionomeric resin per 100 wt % of the resin material is preferably at least 10 wt %, more preferably at least 30 wt %, and even more preferably at least 60 wt %.
  • the spin rate on shots with a driver (W#1) may be high, as a result of which a good distance may not be achieved.
  • additives may be suitably included in the intermediate layer material.
  • pigments, dispersants, antioxidants, ultraviolet absorbers and light stabilizers may be added.
  • the amount added per 100 parts by weight of the base resin is preferably at least 0.1 part by weight, and more preferably at least 0.5 part by weight.
  • the upper limit is preferably not more than 10 parts by weight, and more preferably not more than 4 parts by weight.
  • the intermediate layer material has a specific gravity which is typically less than 1.1, preferably between 0.90 and 1.05, and more preferably between 0.93 and 0.99. Outside of this range, the rebound of the overall ball may decrease and a good distance may not be obtained, or the durability of the ball to cracking on repeated impact may worsen.
  • the cover has a material hardness on the Shore D scale which, although not particularly limited, is preferably at least 35, and more preferably at least 40.
  • the upper limit is preferably not more than 55, more preferably not more than 53, and even more preferably not more than 50.
  • the surface hardness of the sphere obtained by encasing the intermediate layer-encased sphere with the cover (i.e., the ball), expressed on the Shore D scale, is preferably at least 50, more preferably at least 55, and even more preferably at least 58.
  • the upper limit is preferably not more than 66, more preferably not more than 64, and even more preferably not more than 63.
  • the cover has a thickness of preferably at least 0.3 mm, more preferably at least 0.45 mm, and even more preferably at least 0.6 mm.
  • the upper limit in the cover thickness preferably not more than 1.2 mm, more preferably not more than 1.0 mm, and even more preferably not more than 0.8 mm.
  • thermoplastic resins employed as cover stock in golf balls may be used as the cover material.
  • a cover material For reasons having to do with ball controllability and scuff resistance, preferred use can be made of a urethane resin.
  • a material that is composed primarily of a thermoplastic polyurethane it is preferable to use a material that is composed primarily of a thermoplastic polyurethane, and especially preferable to form the cover of a resin composition in which the main components are (I) a thermoplastic urethane and (II) a polyisocyanate compound.
  • the total weight of components (I) and (II) combined be at least 60%, and preferably at least 70%, of the overall amount of the cover-forming resin composition.
  • Components (1) and (II) are described below.
  • the thermoplastic polyurethane (I) has a structure which includes soft segments composed of a polymeric polyol (polymeric glycol) that is a long-chain polyol, and hard segments composed of a chain extender and a polyisocyanate compound.
  • the long-chain polyol serving as a starting material may be any that has hitherto been used in the art relating to thermoplastic polyurethanes, and is not particularly limited.
  • Illustrative examples include polyester polyols, polyether polyols, polycarbonate polyols, polyester polycarbonate polyols, polyolefin polyols, conjugated diene polymer-based polyols, castor oil-based polyols, silicone-based polyols and vinyl polymer-based polyols. These long-chain polyols may be used singly, or two or more may be used in combination. Of these, in terms of being able to synthesize a thermoplastic polyurethane having a high rebound resilience and excellent low-temperature properties, a polyether polyol is preferred.
  • chain extender that has hitherto been employed in the art relating to thermoplastic polyurethanes may be suitably used as the chain extender.
  • low-molecular-weight compounds with a molecular weight of 400 or less which have on the molecule two or more active hydrogen atoms capable of reacting with isocyanate groups are preferred.
  • the chain extender include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol and 2,2-dimethyl-1,3-propanediol.
  • the chain extender is preferably an aliphatic diol having 2 to 12 carbon atoms, and more preferably 1,4-butylene glycol.
  • any polyisocyanate compound hitherto employed in the art relating to thermoplastic polyurethanes may be suitably used without particular limitation as the polyisocyanate compound.
  • use may be made of one or more selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, tetramethylxylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate and dimer acid diisocyanate.
  • thermoplastic polyurethane serving as component (I).
  • Illustrative examples include Pandex T-8295, Pandex T-8290 and Pandex T-8260 (all from DIC Covestro Polymer, Ltd.).
  • thermoplastic elastomer other than the above thermoplastic polyurethanes may also be optionally included as a separate component, i.e., component (III), together with above components (I) and (II).
  • component (III) By including this component (III) in the above resin blend, the flowability of the resin blend can be further improved and properties required of the golf ball cover material, such as resilience and scuff resistance, can be increased.
  • compositional ratio of above components (I). (II) and (III) is not particularly limited. However, to fully elicit the advantageous effects of the invention, the compositional ratio (I):(II):(III) is preferably in the weight ratio range of from 100:2:50 to 100:50:0, and more preferably from 100:2:50 to 100:30:8.
  • thermoplastic polyurethane various additives other than the ingredients making up the above thermoplastic polyurethane may be optionally included in this resin blend.
  • additives other than the ingredients making up the above thermoplastic polyurethane may be optionally included in this resin blend.
  • pigments, dispersants, antioxidants, light stabilizers, ultraviolet absorbers and internal mold lubricants may be suitably included.
  • multi-piece solid golf balls in which the above-described core, inner envelope layer, outer envelope layer, intermediate layer and cover (outermost layer) are formed as successive layers may be carried out by a customary method such as a known injection molding process.
  • a multi-piece golf ball can be produced by successively injection-molding the respective materials for the inner envelope layer, outer envelope layer and intermediate layer over the core in injection molds for each layer so as to obtain the respective layer-encased spheres and then, last of all, injection-molding the material for the cover serving as the outermost layer over the intermediate layer-encased sphere.
  • the encasing layers may each be formed by enclosing the sphere to be encased within two half-cups that have been pre-molded into hemispherical shapes and then molding under applied heat and pressure.
  • the core have a center hardness and a surface hardness
  • the sphere obtained by encasing the core with the inner envelope layer have a surface hardness
  • the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer have a surface hardness
  • the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer have a surface hardness
  • the ball have a surface hardness which together satisfy the following relationship:
  • the above hardness relationship preferably satisfies the following condition:
  • the thicknesses of the inner and outer envelope layers to satisfy the relationship (thickness of inner envelope layer) ⁇ (thickness of outer envelope layer), more preferable for the inner envelope layer to be thicker than the outer envelope layer, and still more preferable for the inner envelope layer to be thicker than the intermediate layer.
  • the thicknesses of the outer envelope layer and the intermediate layer preferably satisfy the relationship (thickness of intermediate layer) ⁇ (thickness of outer envelope layer). It is especially preferable for the intermediate layer to be thicker than the outer envelope layer.
  • the intermediate layer is formed thicker than the cover.
  • the difference in thickness between the intermediate layer and the cover is preferably at least 0.2 mm and not more than 1.2 mm. Outside of this range, it may not be possible to achieve both a good distance and a good controllability in the short game.
  • the value expressed as (combined thickness of inner envelope layer and outer envelope layer) ⁇ (combined thickness of intermediate layer and cover) is at least 0.1 mm, preferably at least 0.3 mm, and more preferably at least 0.4 mm.
  • the upper limit is preferably not more than 1.0 mm, more preferably not more than 0.8 mm, and even more preferably not more than 0.6 mm. Outside of this range, a good distance and a good controllability in the short game may not both be achieved.
  • the number of dimples arranged on the cover surface is preferably at least 250, more preferably at least 300, and even more preferably at least 320.
  • the upper limit is preferably not more than 380, more preferably not more than 350, and even more preferably not more than 340.
  • the dimple shapes used may be of one type or may be a combination of two or more types suitably selected from among, for example, circular shapes, various polygonal shapes, dewdrop shapes and oval shapes.
  • the dimple diameter may be set to at least about 2.5 mm and up to about 6.5 mm
  • the dimple depth may be set to at least 0.08 mm and up to 0.30 mm.
  • the dimple coverage ratio on the spherical surface of the golf ball i.e., the dimple surface coverage SR, which is the sum of the individual dimple surface areas, each defined by the flat plane circumscribed by the edge of a dimple, as a percentage of the spherical surface area of the ball were the ball to have no dimples thereon, to be set to at least 70% and not more than 90%.
  • the value V 0 defined as the spatial volume of the individual dimples below the flat plane circumscribed by the dimple edge, divided by the volume of the cylinder whose base is the flat plane and whose height is the maximum depth of the dimple from the base, to be set to at least 0.35 and not more than 0.80.
  • a coating layer may be formed on the surface of the cover.
  • This coating layer can be formed by applying various types of coating materials. Because the coating layer must be capable of enduring the harsh conditions of golf ball use, it is desirable to use a coating composition in which the chief component is a urethane coating material composed of a polyol and a polyisocyanate.
  • the polyol component is exemplified by acrylic polyols and polyester polyols. These polyols include modified polyols. To further increase workability, other polyols may also be added.
  • polyester polyols it is suitable to use two types of polyester polyols together as the polyol component.
  • a polyester polyol in which a cyclic structure has been introduced onto the resin skeleton may be used as the polyester polyol of component (a).
  • polyester polyols obtained by the polycondensation of a polyol having an alicyclic structure, such as cyclohexane dimethanol, with a polybasic acid and polyester polyols obtained by the polycondensation of a polyol having an alicyclic structure with a diol or triol and a polybasic acid.
  • a polyester polyol having a branched structure may be used as the polyester polyol of component (b).
  • polyester polyols having a branched structure such as NIPPOLAN 800, from Tosoh Corporation.
  • the polyisocyanate is exemplified without particular limitation by commonly used aromatic, aliphatic, alicyclic and other polyisocyanates. Specific examples include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 1,4-cyclohexylene diisocyanate, naphthalene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate and 1-isocyanato-3,3,5-trimethyl-4-isocyanatomethylcyclohexane. These may be used singly or in admixture.
  • organic solvents may be mixed into the coating composition.
  • organic solvents include aromatic solvents such as toluene, xylene and ethylbenzene; ester solvents such as ethyl acetate, butyl acetate, propylene glycol methyl ether acetate and propylene glycol methyl ether propionate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether and dipropylene glycol dimethyl ether; alicyclic hydrocarbon solvents such as cyclohexane, methyl cyclohexane and ethyl cyclohexane: and petroleum hydrocarbon solvents such as mineral spirits.
  • the thickness of the coating layer made of the coating composition is typically from 5 to 40 ⁇ m, and preferably from 10 to 20 ⁇ m.
  • coating layer thickness refers to the coating thickness obtained by averaging the measurements taken at a total of three places: the center of a dimple and two places located at positions between the dimple center and the dimple edge.
  • the coating layer composed of the above coating composition has an elastic work recovery that is preferably at least 60%, and more preferably at least 80%.
  • the coating layer has a high elasticity and so the self-repairing ability is high, resulting in an outstanding abrasion resistance.
  • the performance attributes of golf balls coated with this coating composition can be improved. The method of measuring the elastic work recovery is described below.
  • the elastic work recovery is one parameter of the nanoindentation method for evaluating the physical properties of coating layers, this being a nanohardness test method that controls the indentation load on a micro-newton ( ⁇ N) order and tracks the indenter depth during indentation to a nanometer (nm) precision.
  • ⁇ N micro-newton
  • nm nanometer
  • prior methods only the size of the deformation (plastic deformation) mark corresponding to the maximum load could be measured.
  • the nanoindentation method the relationship between the indentation load and the indentation depth can be obtained by continuous automated measurement.
  • the hardness of the coating layer is preferably at least 40, and more preferably at least 60.
  • the upper limit is preferably not more than 95, and more preferably not more than 85.
  • This Shore M hardness is obtained in general accordance with ASTM D2240.
  • the hardness of the coating layer, expressed on the Shore C hardness scale is preferably at least 40 and has an upper limit of preferably not more than 80. This Shore C hardness is obtained in general accordance with ASTM D2240.
  • coating layer hardnesses that are higher than these ranges the coating may become brittle when the ball is repeatedly struck, which may make it incapable of protecting the cover layer.
  • coating layer hardnesses that are lower than the above range are undesirable because the ball surface more readily incurs damage upon striking a hard object.
  • the difference between the Shore C hardness C M at the midpoint M between the core center and surface and Hc is preferably ⁇ 10 or more, and more preferably ⁇ 5 or more.
  • the upper limit is preferably not more than 10, and more preferably not more than 5.
  • the formation of a coating layer on the surface of golf balls manufactured by a commonly known method can be carried out via the steps of preparing the coating composition at the time of application, applying the composition to the golf ball surface by a conventional coating operation, and drying the applied composition.
  • the coating method is not particularly limited. For example, spray painting, electrostatic painting or dipping may be suitably used.
  • the multi-piece solid golf ball of the invention can be made to conform to the Rules of Golf for play.
  • the inventive ball may be formed to a diameter which is such that the ball does not pass through a ring having an inner diameter of 42.672 mm and is not more than 42.80 mm, and to a weight which is preferably between 45.0 and 45.93 g.
  • Solid cores were produced by preparing rubber compositions for the respective Examples and Comparative Examples shown in Table 1, and then molding and vulcanizing the compositions under vulcanization conditions of 155° C. and 15 minutes.
  • an inner envelope layer was formed by injection molding the inner envelope layer material of formulation No. 1 or No. 4 shown in Table 2 over the core, following which an outer envelope layer was formed by injection molding the outer envelope layer material of formulation No. 2, No. 3, No. 5, No. 6 or No. 7 shown in Table 2.
  • the material of formulation No. 2 in Table 2 was injection molded over the core to form a single envelope layer (outer envelope layer).
  • an intermediate layer was formed by injection molding the intermediate layer material of formulation No. 8, No. 9 or No. 10 shown in Table 2 over the envelope layer-encased sphere obtained above.
  • a cover was formed by injection molding the cover material of formulation No. 11, No. 12 or No. 13 shown in Table 2 over the resulting intermediate layer-encased sphere in each example.
  • a plurality of given dimples common to all the Examples and Comparative Examples were formed at this time on the surface of the cover.
  • Coating Composition I shown in Table 3 below was applied with an air spray gun onto the surface of the cover (outermost layer) on which numerous dimples had been formed, thereby producing golf balls having a 15 ⁇ m-thick coating layer formed thereon.
  • a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet and a thermometer was charged with 140 parts by weight of trimethylolpropane, 95 parts by weight of ethylene glycol, 157 parts by weight of adipic acid and 58 parts by weight of 1,4-cyclohexanedimethanol, following which the temperature was raised to between 200 and 240° C. under stirring and the reaction was effected by 5 hours of heating.
  • the base resin for Coating Composition I in Table 3 was prepared by mixing 23 parts by weight of the above polyester polyol solution together with 15 parts by weight of Polyester Polyol (B) (the saturated aliphatic polyester polyol NIPPOLAN 800 from Tosoh Corporation; weight-average molecular weight (Mw), 1.000; 100% solids) and the organic solvent. This mixture had a nonvolatiles content of 38.0 wt %.
  • B the saturated aliphatic polyester polyol NIPPOLAN 800 from Tosoh Corporation; weight-average molecular weight (Mw), 1.000; 100% solids
  • the elastic work recovery of the coating material was measured using a coating sheet having a thickness of 50 ⁇ m.
  • the ENT-2100 nanohardness tester from Erionix Inc. was used as the measurement apparatus, and the measurement conditions were as follows.
  • Indenter Berkovich indenter (material: diamond; angle ⁇ : 65.03°)
  • the elastic work recovery was calculated as follows, based on the indentation work W elast (Nm) due to spring-back deformation of the coating and on the mechanical indentation work W total (Nm).
  • the Shore C hardnesses and Shore M hardnesses in Table 3 above were determined by fabricating the material being tested into 2 mm thick sheets and stacking three such sheets together to form test specimens. Measurements were taken using a Shore C durometer and a Shore M durometer in accordance with ASTM D2240.
  • the diameters at five random places on the surface were measured at a temperature of 23.9 ⁇ 1° C. and, using the average of these measurements as the measured value for a single core, inner or outer envelope layer-encased sphere or intermediate layer-encased sphere, the average diameter for ten such spheres was determined.
  • the diameter at 15 random dimple-free areas was measured at a temperature of 23.9 ⁇ 1° C. and, using the average of these measurements as the measured value for a single ball, the average diameter for ten balls was determined.
  • a core was placed on a hard plate and the amount of deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) was measured.
  • the amount of deflection refers in each case to the measured value obtained after holding the core isothermally at 23.9° C.
  • the indenter of a durometer was set substantially perpendicular to the spherical surface of the core, and the surface hardness of the core on the Shore C hardness scale was measured in accordance with ASTM D2240.
  • Cross-sectional hardnesses at the center of the core and at given positions in each core were measured by perpendicularly pressing the indenter of a durometer against the place to be measured in the flat cross-sectional plane obtained by cutting the core into hemispheres. The measurement results are indicated as Shore C hardness values.
  • Cc be the Shore C hardness at the core center
  • Cs be the Shore C hardness at the core surface
  • C M be the Shore C hardness at a midpoint M between the core center and surface
  • C M+2.5 C M+5.0 and C M+7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core surface side
  • C M ⁇ 2.5 C M ⁇ 5.0 and C M ⁇ 7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core center side
  • the surface areas A to F defined as follows
  • FIG. 2 is a graph that illustrates surface areas A to F using the core hardness profile data from Example 1.
  • the resin materials for each of these layers were molded into sheets having a thickness of 2 mm and left to stand for at least two weeks, following which the Shore D hardnesses were measured in accordance with ASTM D2240.
  • the surface hardnesses were measured by perpendicularly pressing an indenter against the surfaces of the respective spheres.
  • the surface hardnesses of the balls (covers) were values measured at dimple-free areas (lands) on the surface of the ball.
  • the Shore D hardnesses were measured with a type D durometer in accordance with ASTM D2240.
  • a driver (W#1) was mounted on a golf swing robot and the distance traveled by the ball when struck at a head speed of 45 m/s was measured and rated according to the criteria shown below.
  • the club used was the TourStage X-Drive709 D430 Driver/2013 model (loft angle, 9.5°) manufactured by Bridgestone Sports Co., Ltd.
  • the spin rate was measured immediately after the ball was similarly struck.
  • a sand wedge was mounted on a golf swing robot and the amount of spin by the ball w en struck at a head speed of 22 m/s was rated according to the criteria shown below.
  • the sand wedge was the TourB XW-1/2018 model (loft angle, 56°) manufactured by Bridgestone Sports Co., Ltd.
  • a non-plated pitching sand wedge was set in a swing robot and the ball was hit once at a head speed (HS) of 35 m/s, following which the surface state of the ball was visually examined and rated as follows.
  • HS head speed
  • Comparative Example 1 the surface hardness of the outer envelope layer was lower than the surface hardness of the core. As a result, the ball had an increased spin rate on shots with a driver and thus a poor distance.
  • the surface hardness of the inner envelope layer was the same as or lower than the surface hardness of the core, and the surface hardness of the envelope layer was lower than the surface hardness of the core.
  • the ball had an increased spin rate on shots with a driver and thus a poor distance.
  • the ball in Comparative Example 6 was a four-piece solid golf ball having a single envelope layer.
  • the spin rate on shots with a driver (W#1) rose, resulting in a poor distance.
  • the core hardness profile had a (surface areas D+E+F) ⁇ (surface areas A+B+C) value of less than 3.
  • the spin rate of the ball on shots with a driver (W#1) rose and so the distance was poor.
  • the surface hardness of the outer envelope layer was higher than the surface hardness of the inner envelope layer and the ball had a feel at impact that was too hard.
  • the core hardness profile had a (surface areas D+E+F) ⁇ (surface areas A+B+C) value of less than 3.
  • the spin rate of the ball on shots with a driver (W#1) rose and so the distance was poor.
  • the surface hardness of the outer envelope layer was higher than the surface hardness of the inner envelope layer and the ball had a feel at impact that was too hard.

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US20090111611A1 (en) * 2007-10-29 2009-04-30 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100048326A1 (en) * 2007-10-29 2010-02-25 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100190580A1 (en) * 2009-01-28 2010-07-29 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100234138A1 (en) * 2007-10-29 2010-09-16 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20110224024A1 (en) * 2010-03-10 2011-09-15 Nike, Inc. Golf Ball Having A Protective Coating
US20160279484A1 (en) * 2015-03-24 2016-09-29 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20160367864A1 (en) * 2013-10-08 2016-12-22 Dunlop Sports Co. Ltd. Golf ball
US20170333759A1 (en) * 2014-12-19 2017-11-23 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
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JP3760972B2 (ja) * 1999-07-28 2006-03-29 ブリヂストンスポーツ株式会社 ソリッドゴルフボール
US8827839B2 (en) * 2010-12-17 2014-09-09 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US9033824B2 (en) * 2011-12-16 2015-05-19 Bridgestone Sports Co., Ltd. Golf ball

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US6527652B1 (en) * 1999-07-28 2003-03-04 Bridgestone Sports Co., Ltd. Solid golf ball
US20090111611A1 (en) * 2007-10-29 2009-04-30 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100048326A1 (en) * 2007-10-29 2010-02-25 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100234138A1 (en) * 2007-10-29 2010-09-16 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20100190580A1 (en) * 2009-01-28 2010-07-29 Bridgestone Sports Co., Ltd. Multi-piece solid golf ball
US20110224024A1 (en) * 2010-03-10 2011-09-15 Nike, Inc. Golf Ball Having A Protective Coating
US20160367864A1 (en) * 2013-10-08 2016-12-22 Dunlop Sports Co. Ltd. Golf ball
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