JP3426212B2 - Golf ball and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD This patent application is a partial continuation application of the pending patent application No. 08 / 482,518 filed on June 7, 1995, and the patent application is referred to as a reference of the present invention. To do.

[0002]

BACKGROUND OF THE INVENTION Current golf balls can be classified as one of two categories: solid balls and wound balls. The first category of solid balls includes monolithic or one-piece golf balls as well as multi-piece golf balls. Rarely used as a competition ball, one-piece golf balls are typically manufactured from solid pieces of polybutadiene rubber,
It has dimples formed on its surface. Although these integrated balls are inexpensive and have excellent durability, they are not generally used as practice balls because they do not give a predetermined flight distance when hit. In contrast, multi-piece solid balls are usually
It consists of a core made of a rigid polymeric material, made of the ionomer resin DuPont SURLYN, covered by a discontinuous cut-resistant cover. Due to its durability and higher flight distance, and low spin characteristics that produce low hook and slicability, this type of ball is
It has the highest rating among ordinary golf players.

Wound golf balls are
Manufactured by winding an elastic winding around a solid rubber or liquid filled central member. A cover, usually Surlyn or balata, is molded over the winding to form the wound ball. This winding process will, of course, entrap some amount of air within the layers of the winding. The air entrapped within the wound ball provides several properties that are considered to be preferred by many golfers. Due to its compressibility, the air provides high resilience due to its soft "feel" at impact and its high efficiency (low damping) like a spring. For skilled golfers, these wound balls typically provide higher spin rates and more control over ball flight than solid balls. Unfortunately, wound golf balls are more difficult and expensive to manufacture than solid golf balls. Also, wound balls are
It has a relatively short shelf life and has less resistance to some types of damage than solid balls.

Utilizing the technology for manufacturing solid-structured balls,
Various attempts have been made to mimic the benefits of wound balls. However, these balls generally utilize a softer core material, a softer cover material, a layer of softer material combined with known materials or combinations thereof. An example of such a ball is the Titleist (T
itleist) HP2, Pinnacle P
erformance), Ultra Competition
ition), Ultra Tour Balata,
Maxfli HT Hi Spin,
Precept EV Extra Spi
n), Altus Newing, Top Flight Tour Z-Balata, Top Flight Tour and Casco
o) Includes "Dual Core" balls. U.S. Pat. No. 4,650,193 issued to Molitor also discloses golf balls made from relatively "soft" materials. Although these solid construction golf balls often provide improved feel and playing characteristics similar to wound balls, they cannot fully incorporate the same predetermined characteristics as wound balls. Moreover, these flexible materials often provide poor resilience and / or durability.

The present invention employs a different method. Instead of using a soft yet incompressible material, a compressible material such as flexible shell microspheres and gas is used in the core of a golf ball having a solid structure. This method provides a much better imitation of the effect of the entrapped air in a wound golf ball, while utilizing a method similar to that of a loyal golf ball. The result is a ball having the soft feel and high resilience of a golf ball with a wound structure, combined with the ease of manufacture, good shelf life and durability of a solid structure ball.

Although conventional golf balls use a gaseous component, these balls were typically the only balls or covers for a special purpose in which such materials were incorporated. . See, for example, US Pat. Nos. 5,150,906 and 4,274,637 to Morita et al. And US Pat. No. 4,431,193 to Nesbitt. A representative ball for special purposes is described in Schenk, U.S. Pat.No. 4,085,937, as described in U.S. Pat.No. 4,836,552 to Pukett et al. Buoyant balls, as described above, and "Nerf" -type toys and practice balls. In these balls, a gas is incorporated within the ball material to reduce the weight of the ball and / or cause damage upon impact with an object. They do not exhibit the feel or performance of golf balls with a normal bobbin or solid structure in any way.

In addition, some prior art balls contain gas-containing cells as glass microspheres, but such cells do not impart impact compressibility to the balls. The glass wall of the microsphere is rigid. An example of such a ball containing rigid glass microspheres is shown in U.S. Pat.No. 5,482,285 to Yabuki et al., Which contains glass microspheres,
It is disclosed that the specific gravity of the outer core of the ball is reduced to the range of 0.2-1. Similarly U.S. Pat.
No. 9,116 also discloses the inclusion of incompressible glass microspheres as a filler.

[0008]

SUMMARY OF THE INVENTION The present invention relates to multi-piece golf balls and methods of making the same. In particular, the present invention has been completed,
For regular long distance use, a multi-piece golf ball with a solid structure is contemplated, which comprises a core made of a material and a spherical cover or shell of polymeric material, within which the compressible material is compressible. Incorporation of gaseous or cellular materials. The core includes an inner portion and an outer portion. In another embodiment, the core comprises inner and outer layers. The compressible material, eg, a plurality of gas-containing compressible cells, is dispersed or distributed in a limited portion of the core, such as the outer or inner portion, so that the portion containing the compressible material is 1 It has a specific gravity exceeding.
Preferably, the specific gravity is about 1.05 to 1.15. Also, the compressible cells can be distributed throughout the core.

In one aspect, the cell comprises a plurality of microspheres having a flexible outer shell. The shell may be made of a polymer such as an acrylonitrile copolymer. The cell diameter is preferably less than or equal to approximately 10% of the core diameter. Also, the cell comprises about 5-50% by volume of the total core, and more preferably 10-1.
Make up 5% by volume. When the core has an inner layer and an outer layer, the outer layer of the core preferably has a thickness of 0.05 to 0.80 inches, and more preferably the thickness of the outer layer is in the range of 0.10 to 0.25 inches. It is in.

The present invention further provides a method for making a complete, regular, long-distance, solid-structured, multi-piece golf ball that includes a discontinuous cover and core, wherein the core comprises: An inner portion and an outer portion are included, the outer portion includes a plurality of gas-containing compressible cells dispersed therein, and the outer portion has a specific gravity of greater than 1. The method comprises the steps of manufacturing the cell by a method selected from the group consisting of foaming using a blowing agent, gas injecting, and incorporating a plurality of microspheres having a flexible outer surface. The invention also relates to a method of making a golf ball, wherein the core is dispersed throughout.
The core comprises a plurality of gas-containing compressible cells and the core has a specific gravity of greater than 1. The present invention further contemplates solid structure golf balls having the advantageous features of both wound and solid structure type golf balls. Golf balls made in accordance with the present invention have a combination of the feel and playing characteristics of a ball with a wound structure and the shelf life and durability of a golf ball with a solid structure.

Further, the golf ball of the present invention will have advantages over both conventional solid and wound ball constructions in cold climates. Under such circumstances, balls having a solid structure known in the art exhibit an extremely hard feel due to the toughness of the material. However, they retain most of their resilience, so they do not significantly reduce their flight distance. On the other hand, a ball with a conventional thread-wound structure maintains most of its soft feel (because the air taken in does not develop significant toughness), but loses resilience when wound under the high tension, resulting in a greater distance. Drop it. The balls produced in accordance with the present invention maintain the flexibility of wound balls and maintain resilience like balls having a solid structure. Another object of the present invention is to provide a golf ball having certain characteristics of a ball having a wound structure and the simplicity and cost saving in manufacturing the ball having a solid structure. The present invention is also directed to the manufacture of golf balls having a solid structure, which have the performance characteristics of wound balls and the advantages of balls having a solid structure.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The solution of the present invention resides in the incorporation of a compressible material within the structure of the golf ball. As used herein, a "compressible material" is a material whose density is significantly affected by pressure or temperature. Gases are generally considered to be compressible materials, while liquids and solids are considered to be incompressible. As defined in the present invention, the term "core" means a single core as well as multiple cores. The compressible material of the present invention may be incorporated throughout the core, or at least a portion or layer of the core. Preferably, the compressible gaseous material is incorporated into the outer portion or layer of the core so that the resulting golf ball behaves and behaves more like a wound ball. The thickness of the layer in a multi-layer ball containing the compressible material is preferably in the range of about 0.05 to 0.80 inches, which is generally the diameter of the entire core. More preferably, the layer thickness is in the range of about 0.10 to 0.25 inches.

The accompanying drawings illustrate three aspects of the present invention. These figures are given for a better understanding of the invention and should not be considered as limiting the scope of the claims of the invention in any way. FIG. 1 illustrates a golf ball having a single core 2, which includes a compressible material 6 on its outer portion. To complete this ball, a cover 3 is molded on the core 2. In Figure 2,
The ball 1 has a multi-layer core 2 which comprises an inner core layer 4
And an outer core layer 5. The compressible material 6 is incorporated into the outer core layer 5. In FIG. 3, the ball includes a single core 2, where the compressible material 6 is incorporated throughout the core. Alternatively, the core in this aspect may be multi-piece.

Suitable core materials into which the compressible gaseous substance can be incorporated include solid, liquid and semi-solid substances such as pastes. Generally, the core material is essentially incompressible. Materials useful in forming such cores include polybutadiene, which includes
To make almost all commercially available golf ball cores,
It is a polymer currently used. Also, various thermoplastics such as DuPont Surlyn, ionomer resins, DuPont Hytrel, or BF.
Goodrich's Estane, or blends thereof, can be used. Further, materials that normally do not exhibit sufficient resilience for use in golf ball cores are satisfactory and usable when the compressible gaseous material is incorporated therein. One such example is polyurethane.

The appropriate ratio of compressible gaseous material to core material will depend on the core material used, as well as the performance characteristics or effects desired for the golf ball. Preferably, the compressible material is evenly distributed. Generally, a range of about 5-50% by volume of the compressible material is suitable, based on the core, core layer or core portion containing the compressible material. For outer core portions or layers having a thickness equivalent to that of the wound layer in the wound ball, 10-15% by volume of the outer core layer of compressible material is preferred. However, made of a tougher material,
For thinner parts / layers or parts / layers, higher ratios of compressible material to core material up to about 50% are preferred.

However, in order to best mimic a wound golf ball, the amount of compressible material to be incorporated should be such that the specific gravity of the layer or portion of the core containing the compressible material exceeds 1. Should be. Preferably, this specific gravity is 1.05 when the core material is polybutadiene.
Is. Also, if the compressible material is disposed on the outer core layer or portion, such layer or portion may be
Specific gravities above 1 keep spin rates low, which is often desirable. The incorporation of an amount of compressible material that reduces the specific gravity of such layers or parts to less than 1 is undesirable. The use of the compressible material typically
The amount of compressible material used is preferably similar to this amount of entrapped air, as it is to simulate the amount of air entrapped during winding of a ball with a wound structure. However, for a portion or layer of the core containing the compressible material to achieve a specific gravity of 1 or less, an amount of such material that exceeds the amount of air entrapped in the wound ball is required. It is said that

The compressible material can be incorporated into the core polymer in a number of ways. These core polymer materials can be "foamed" by various techniques,
The techniques include, but are not limited to, the use of blowing agents, gas injection, mechanical aeration and two-component reaction systems. Moriter, U.S. Pat. No. 4,274,637, discloses the use of blowing agents and gas injection to foam polymeric materials. The blowing agent decomposes to form a gas that is absorbed by the core polymer material,
The material is foamed. This gas then expands to form a foam core material, i.e. a foam core material. Foaming by gas injection can be accomplished by injecting a gas, such as nitrogen, air, carbon dioxide, etc., into the material under pressure. When this gas expands, the material foams.

Alternatively, the gas can be added to the core material by mixing the gas enclosed in the microspheres. This addition can be done by incorporating gas-filled microspheres into the polymer composition. However, such an enclosing body for encapsulating gas, when the impact of the ball by the golf club,
It must be made of a flexible material sufficient to allow gas compression inside. Such encapsulating materials include polymeric microspheres, such as acrylonitrile copolymer microspheres, as well as expandable microspheres. However, glass microspheres are not suitable for the present invention because of their rigidity. Regardless of the material from which these microspheres are formed, suitable microspheres, when incorporated into the core material, are small enough to act like a continuous medium,
Should be size. Typically, at most 10% of the thickness of the core layer or portion incorporating the compressible material
A small spherical diameter is suitable.

Further, various crosslinkers and fillers are typically added to the core material along with the gaseous material in a manner known in the art. Suitable cross-linking agents include metal salts of unsaturated carboxylic acids. These salts are generally zinc diacrylate or zinc dimethacrylate. Of these two crosslinkers, zinc diacrylate has been found to give golf balls with a higher initial velocity than zinc dimethacrylate. Suitable fillers that can be used in the present invention include free radical initiators that are used to promote crosslinking of the salt and polybutadiene. Suitable as this free radical initiator are peroxide compounds such as dicumyl peroxide, 1,1-di (T-butylperoxy) 3,3,5-trimethylcyclohexane, aa bis (T-butylperoxy). Diisopropylbenzene, 2,5-dimethyl-2,5-di (T-butylperoxy) hexane, or di-T-butylperoxide, and mixtures thereof. Also, other substantially inert fillers such as zinc oxide, barium sulfate and limestone, and additives can be added to the mixture. The maximum amount of filler that can be used in the composition is governed by the filler as well as the maximum weight requirement set by the USGA. Suitable fillers commonly used have a specific gravity in the range 2.0-5.6.

There are two basic techniques commonly used in golf ball manufacturing. That is, compression molding and injection molding techniques. Both of these techniques are well known in the art. To form a golf ball of the present invention comprising the compressible material dispersed throughout the core or a portion of the core, the compressible material may be added by adding the microspheres, or any number of Or other foaming technology,
To polybutadiene or some other suitable core material,
Be compounded. After the addition of the compressible substance, the composition of the core material can be extruded to obtain a preform suitable for molding. Then, compression molding this preform,
It can be a spherical core. The cover, typically made of thermoplastic material, is then injection molded directly around the core, or compression molded using a preformed hemisphere of cover material placed around the core. . Such cover materials, such as Surlyn or balata gum, are known in the art.

In the context of the golf ball of the present invention, wherein the compressible material is incorporated into the discrete outer layer of the core of the ball of the present invention, the center of the core is compression molded core material. And produced by forming a sphere with a diameter smaller than the diameter of the completed core. The outer layer of the core, incorporating the compressible material, is formed about the center of the core by either injection molding or compression molding. Finally, the cover is injection or compression molded around the core by known means. While it is clear that the invention described herein meets the above objectives, it will be understood that various modifications and modes can be devised by those skilled in the art. Accordingly, the appended claims are intended to cover all such modifications and aspects as fall within the true spirit and scope of this invention. [Brief description of drawings]

FIG. 1 is a cross-sectional view of a golf ball of the present invention, where a compressible material is incorporated into the outer portion of the solid core.

2 is a cross-sectional view of a golf ball of the present invention, in which a compressible material is incorporated into the outer layer of the core.

FIG. 3 is a cross-sectional view of a golf ball of the present invention, in which a compressible material is incorporated throughout the solid core.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References Table 2000-513597 (JP, A) US Patent 4085937 (US, A) US Patent 5688192 (US, A) US Patent 4839116 (US, A) US Patent 4805914 ( US, A) US Patent 4863167 (US, A) US Patent 4274637 (US, A) UK Patent Application Publication 2335370 (GB, A) (58) Fields searched (Int.Cl. ⁷ , DB name) A63B 37/04 A63B 37/12 A63B 45/00

Claims (20)

(57) [Claims] 1. A completed, regular long-distance, solid structure, multi-piece golf ball comprising a discontinuous cover and a core, the core including an inner portion and an outer portion. Including an outer portion dispersed within it,
Having a plurality of gas-containing compressible cells and said outer portion being one
A golf ball characterized by having a specific gravity exceeding the range. 2. The specific gravity is 1.05 to 1.15.
The described golf ball. 3. The golf ball of claim 1, wherein the compressible cells are dispersed throughout the core and the entire core has a specific gravity of greater than 1. 4. The golf ball of claim 3, wherein the cell comprises a plurality of microspheres having a flexible outer surface. 5. The golf ball according to claim 4, wherein the surface is formed of a polymer. 6. The golf ball of claim 5, wherein the polymer is an acrylonitrile copolymer. 7. Each of the microspheres has a diameter of about ≦ 1 of the entire core.
The golf ball of claim 4, having a diameter corresponding to 0%. 8. The golf ball of claim 1, wherein the cell comprises about 5-50% by volume of the total core. 9. The cell comprises about 10-15% by volume of the total core.
The golf ball of claim 8, which comprises: 10. A completed, regular long range, solid structure, multi-piece golf ball comprising a discontinuous cover and a layered core, the core including an outer layer and an outer layer. A golf ball comprising the above-mentioned inner layer, wherein the outer layer has a plurality of gas-containing compressible cells dispersed therein, and the outer layer has a specific gravity of more than 1. 11. The specific gravity is 1.05 to 1.15.
0 golf ball. 12. The golf ball of claim 10, wherein the compressible material is dispersed within the outer layer of the core having a thickness of 0.05-0.80 inches. 13. The golf ball of claim 12, wherein the compressible material is dispersed within the outer layer of the core having a thickness of 0.10 to 0.25 inches. 14. The golf ball of claim 10, wherein the compressible cells are dispersed throughout the core and the entire core has a specific gravity of greater than 1. 15. The golf ball of claim 14, wherein the cell comprises a plurality of microspheres having a flexible outer surface. 16. The golf ball of claim 15, wherein the surface is made of a polymer. 17. The golf ball of claim 16, wherein the polymer is an acrylonitrile copolymer. 18. The golf ball of claim 15, wherein each of the microspheres has a diameter corresponding to about ≦ 10% of the diameter of the entire core. 19. A method for manufacturing a completed, regular long-distance, solid structure, multi-piece golf ball, the golf ball comprising a discontinuous cover and a core. The core includes an inner portion and an outer portion, the outer portion having a plurality of gas-containing compressible cells dispersed therein, and the outer portion having a specific gravity of greater than 1.
The method comprises the step of producing the cell by a method selected from the group consisting of a foaming method using a foaming agent, a gas injection method and a method of compounding a plurality of microspheres having a flexible outer surface. A method for manufacturing a golf ball, comprising: 20. A method for manufacturing a completed, regular long-distance, solid structure, multi-piece golf ball, the golf ball including a discontinuous cover and a core. The core has a plurality of gas-containing compressible cells dispersed throughout it, and the core has a specific gravity of more than 1, the method comprising foaming using a blowing agent, gas injection and A method of making a golf ball comprising the step of making the cell by a method selected from the group consisting of blending a plurality of microspheres having a flexible outer surface.