JP2004283558A - Golf ball cover of segmented polyurethane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the physical property of a golf ball. <P>SOLUTION: A golf ball comprises a cover, a core, and at least one intermediate layer interposed between the cover and the core, wherein the cover is formed from a blend comprising a segmented polyurethane elastomer copolymers of polyether (or ester)-ester and polyether (or ester)-amide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to golf balls, and more particularly, to the use of segmented polyurethane materials in golf ball layers to improve the physical properties of golf balls.

Conventional golf balls can be divided into two general types or groups: solid balls and wound balls. The differences in play characteristics provided by these different types of structures are very significant.
Balls having a solid construction are generally the most popular for ordinary hobby golfers because they are extremely durable balls and still provide maximum flight distance. Solid balls are generally made of a single solid core, usually a crosslinked rubber core, and are covered by a cover material. Generally, the solid core is made of polybutadiene chemically cross-linked with zinc diacrylate and / or a similar cross-linking agent and covered with a tough, cut-resistant blend cover. The cover is typically a material such as Surlyn (Ionomer resin from DuPont). Such a combination provides a high initial velocity for the ball which results in improved flight distance. Because these materials are very hard, two-piece balls have a hard "feel" when struck with a club. Similarly, due to their hardness, these balls have relatively low spin rates and provide great flight distance.

Wound balls generally have a solid rubber or liquid center core around which several yards of stretched elastic yarn or yarn are wrapped. The wound core is then covered with a durable cover material such as an ionomer or polyurethane. Wound balls are generally soft and give more spin so that a skilled golfer can adjust the flight of the ball. In particular, on approach shots into the green, the high spin rate of the soft wound ball allows the golfer to stop the ball very close to the ball landing.
Golf ball design techniques have been developed by the United States Golf Association (USGA) at a USGA accredited event when hitting with a device having a speed of 43.5 m (143 ft) / sec. Progress has been made to the point that rules have been enacted that prohibit the use of golf balls that can achieve an initial speed (hereinafter referred to as the "USGA test").
Manufacturers produce golf balls that consistently achieve the highest possible speed in the USGA test without exceeding this limit, and that are available in a range of different properties and properties, such as speed, spin and compression. I put a lot of emphasis on things. Thus, the variety of different balls helps to meet the needs and wishes of a wide range of golfers.

Regardless of the shape of the ball, players generally seek a golf ball that achieves the maximum flight distance that requires a high initial velocity when hit. Accordingly, in an effort to meet market demands, manufacturers strive to produce golf balls with high initial speeds.
As a result, golf ball manufacturers are renewed to provide golf balls of all skillful levels with golf balls that achieve the best skill and to discover compositions that provide high compression ball performance at low compression. Is constantly searching for new ways.
The physical properties of a golf ball are determined by the combined properties of the core, optional interlayer and cover. These, in turn, depend on the respective chemical composition. Certain ball compositions provide increased flight distance. Another composition gives improved spin. Manufacturers are constantly seeking to develop ideal materials. For example, thermoplastic polyurethane ureas have been tested for their inherent ability to provide materials with very high tensile strength, a very desirable property in the manufacture of golf balls.

  Segmented polyurethanes are solvent-based elastomers. These can be processed by a method of combining an aromatic polyether urethane urea, a soft segment polycarbonate, a hard segment diphenylmethane diisocyanate, and a mixed diamine. The hard segment is usually the reaction product of an aromatic diisocyanate and a low molecular weight chain extended dialcohol or diol. The soft segment may be synthesized from a polycarbonate polyol having terminal hydroxyl (-OH) groups. The hydroxyl groups create urethane groups, while the reaction between the isocyanate and the urea groups present forms allophanate groups that can produce small amounts of covalent crosslinks. Upon heating, the hydrogen bonded hard segments dissociate from the allophanate crosslinks, allowing the polymer to melt and flow. Also, dissolution in polar solvents can break hydrogen bonds holding hard segments on adjacent chains. Once these crosslinks are broken, the polymer can be processed as a golf ball layer. Upon cooling or solvent evaporation, the hard segments separate from the soft segments and recombine by hydrogen bonding. This restores the original mechanical properties of the thermoplastic elastomer. Conventional segmented polyurethanes generally have excellent physical properties combined with high elongation and high tensile strength, but they are inherently solvents. First, the primary amine reacts with the isocyanate to form a secondary amine, and then the remaining hydrogen on the secondary amine reacts with the other isocyanate moieties a second time to form a tertiary amine . This second reaction forms crosslinks and results in a thermoset material. Since secondary amines cannot form a second reaction, the urea groups cannot further react with isocyanates to form crosslinks and the product is a thermoplastic which is cured with the amine.

  Accordingly, there is a need for golf balls that include a segmented polyurethane for improved golf ball performance. By varying the hard segment of urea during synthesis, a whole family of polymers of the relevant chemistry with a wide range of hardness, modulus, tensile strength and elongation can be produced.

The present invention relates to the use of a segmented polyurethane comprising urea in the hard segments for forming a golf ball core, cover or intermediate layer.
A first embodiment is a golf ball comprising a core and a cover, at least one of which is formed from a segmented polyurethane comprising an aromatic urea hard segment and a soft segment based on polycarbonate. BioSpan C® is an example of a suitable segmented polyurethane material, commercially available from Polymer Technology Group Inc.
Another embodiment of the present invention comprises a segmented polyurethane comprising an aromatic urea hard segment and a soft segment based on polyether. One example is BioSpan SPU, which is a registered trademark of a segmented polyurethane material commercially available from Polymer Technology Group.

Most preferably, the segmented polyurethane of the present invention is an intermediate layer. Other embodiments of the invention include polycarbonate-polyurea block copolymers, copolymers including ionomers and highly neutralized polymers, epoxy, styrene and olefin based homo- and copolymers (including metallocene and single site). Blends with at least one thermoplastic or thermoset polymer, including block copolymers of: polyamide; polyester; polydiene; polyether (or ester) -ester and polyether (or ester) -amide. Examples of these are U.S. Pat. Nos. 4,675,361, 5,428,123, 5,589,563, and 5,863,627. No. 5,221,724 and US Pat. No. 5,461,134, which are incorporated herein by reference in their entirety.
The present invention is preferably a two-piece or multi-layer golf ball having a coefficient of restitution greater than about 0.7 measured at an input speed of 125 feet per second and an Atti compression of at least about 50. The intermediate layer is a preferred use of the present invention and comprises a segmented polyurethane having a material tensile strength greater than about 20.6 MPa (about 3000 psi).
Surface modified end groups (SMEs) are surface-active oligomers that are covalently attached to the base polymer during synthesis. The present invention can include SMEs that adjust the surface chemistry without compromising the bulk properties of the polymer. Key surface properties, such as abrasion resistance, are continuously enhanced without further post-processing or topical coating.

Golf ball 10 of the present invention includes at least one layer of core 14, at least one layer of cover 12 concentrically disposed about core 14, optionally between cover 12 and core 14. At least one intermediate layer 16 may be included. Any of these layers may comprise a thermoplastic urethane copolymer having polycarbonate in the soft segment of the copolymer, but preferably, the intermediate layer may comprise an expanded elastomeric material. The core center 18 may include a solid, hollow, liquid-filled, or gel-filled interlayer.
Currently available segmented polyurethanes include Biospun (registered trademark of Polymer Technology Group). The polymer is made such that the material exhibits good oxidative stability, excellent mechanical strength and abrasion resistance, and excellent optical properties that are extremely important to golf ball manufacturers. The ultimate tensile strength of the biospan compound may exceed 10,000 psi.

U.S. Pat. No. 5,756,632 describes a process for processing commercially available biospan. Biospan C is a segmented polyurethane formed as a reaction product of a hydroxyl terminated polycarbonate, an aromatic diisocyanate and a low molecular weight diamine used as a chain extender. Biospan SPU is a segmented polyether formed as a reaction product of a hydroxyl terminated polyether, an aromatic diisocyanate and a low molecular weight diamine. In a preferred embodiment, the reaction of the isocyanate groups with the low molecular weight bifunctional reagent results in chain extension, resulting in the formation of hard segments connecting the soft segments of the polycarbonate via urethane groups. When the chain extender is a diol, the hard segments have repeating units linked by urethane groups, while when the chain extender is a diamine, the hard segments contain urea groups. In the latter case, the resulting polymer is called a polyurethaneurea. Polyurethaneureas are highly phase separated elastomers and are generally manufactured in solution unless the diamine chain extender is completely replaced with water. Useful urea-containing urethanes are obtained when the total content of the hard segments is reduced. These are elastomers close to the properties of natural rubber. Polyurethane ureas show good phase separation, low hardness and extreme toughness.
SME, suitable compatibilizers, colorants, reaction accelerators, crosslinkers, blowing agents, dyes, lubricants, fillers (including density modifiers), excipients, processing aids, and polymeric materials and / or Additional components, such as other compounds commonly added to golf ball compositions, may be added to the segmented polyurethane component of the present invention.

Surface-modified end groups (SMEs) are surface-active oligomers that are attached to the base polymer during synthesis and include silicones, sulfonates, fluorocarbons, polyethylene oxides and hydrocarbon groups, which allow surface chemistry to be performed without compromising the bulk of the polymer. Adjust. Key surface properties, such as abrasion resistance, are continuously enhanced without further post-processing or topical coating. The addition of SME provides a range of base polymers that can actually achieve the desired surface chemistry without the use of additives. This leaves the original polymer backbone intact, and the polymer retains strength and processing performance. Having all of the polymer chains carry a surface modifying moiety eliminates many of the potential problems with additives.
Any golf ball component composition that does not include the segmented polyurethanes of the present invention disclosed herein can be a composition known to those skilled in the art. Such compositions can be readily selected by one skilled in the art.
The resulting golf ball generally has a rebound of greater than about 0.7, preferably about 0.75, and more preferably greater than about 0.78 when measured at an input speed of 125 feet / second. With coefficients. Also, golf balls generally have an Atti compression of at least about 40, preferably about 50-120, and more preferably about 60-100. As used herein, the term "compression" refers to compression measured on an ATTI Compression Gauge.
These gauges are known to those skilled in the art and are commercially available from Atti Engineering, Union City, NJ.

  The present invention relates to golf balls of any size. The USGA standard limits the size of a competitive golf ball to a diameter greater than 1.68 inches (42.672 mm), but any golf ball size can be used for leisure golf play. The preferred diameter of the golf ball is from about 1.68 inches to about 1.76 inches (42.672 mm to 44.704 mm). Most preferred is a diameter of from about 1.68 inches to about 1.74 inches (42.672 mm to 44.196 mm). The core of the ball has a diameter of about 1.0 to about 1.62 inches (25.4 mm to 41.148 mm). Golf ball covers typically have a thickness of at least about 0.062 inches (0.762 mm). The cover of the present invention preferably has a thickness of about 0.02-0.125 inch, more preferably about 0.03-0.10 inch. is there. Golf balls also generally have a dimple coverage of at least 60% of the surface area, preferably at least about 70%. The cover layer has a Shore D hardness of at least about 20, preferably about 30-65. Golf balls of the present invention have a compression of less than about 120.

The golf balls of the present invention can be manufactured in a number of ways. The core may be manufactured in a manner known in the art using a conventional wound core structure or a conventional solid structure of one or more layers. The wound core structure can be a solid rubber-based center or a liquid-filled center around which a length of elastic yarn is wound. A typical solid structure comprises cis-1,4-polybutadiene, preferably cross-linked with a metal salt of an unsaturated fatty acid such as zinc diacrylate. A typical multilayer structure may include multilayer cores of different polybutadiene-based materials to form the inner and outer layers.
These core structures are then coated, using conventional compression injection molding or casting methods, with a cover composition comprising a segmented polyurethane such as Biospan C comprising a soft segment polycarbonate and a hard segment of urea. . Biospun SPU contains polyether in the soft segment. There are many ways to utilize this material. As an example, Biospan C is formed on a golf core in a one-shot (or separately, prepolymer approach) process. This includes, for example, a soft segment of polycarbonate polyol (PC) and a hard segment of 4,4'-diphenylmethane diisocyanate (MDI), ethylenediamine (ED) and 1,3-cyclohexanediamine (CHD) and common end groups, For example, it is performed by mixing with dodecylamine (DDA). The cover is preferably about 1.27 mm to 2.54 mm (about 0.05 to 0.10 inches) thick.

In other embodiments, the segmented polycarbonate-polyurethane or polyether-polyurethane copolymers are ionomers and their acid ionomers, including highly neutralized acid polymers; polyolefins; polyacrylates; polyamides; polyphenylene oxides; Block copoly (ether or ester-amide); block copoly (ether or ester-ester); polysulfone, reaction injection moldable thermoplastic and thermoset polymers; styrene-butadiene block copolymers and hydrogenated derivatives thereof; Vulcanized ethylene-propylene rubber; polyvinylidene fluoride; acrylonitrile-butadiene-styrene copolymer; epoxy resin; polystyrene; acrylic resin; Is at least one thermoplastic or thermosetting polymer blended including ene and polyester.
Other embodiments include a core, an inner cover having a flexural modulus greater than 50,000 psi, and a cover comprising a segmented polycarbonate-urethane elastomer. The cover preferably has a thickness of about 0.02-0.05 inches (0.508 mm to 1.27 mm) and an initial modulus of less than 10,000 psi (68.9 MPa). In other embodiments, the initial modulus is greater than 10,000 psi. The segmented polyurethane elastomer preferably has an ultimate elongation of at least about 40% to 1000%, preferably about 400% to 800%.

Another embodiment includes a core, a cover, and an intermediate layer that includes a segmented polycarbonate-urethane elastomer. The intermediate layer preferably has a thickness of about 0.02-0.08 inch (0.508 mm to 2.032 mm) and less than about 10,000 psi (68.9 MPa), preferably 2.0 to 68 psi. It has an initial modulus of about 9 MPa (about 300 to 10,000 psi).
In some embodiments, the core comprises a polybutadiene rubber and the cover and the intermediate layer comprise a thermoplastic silicone-urethane copolymer. The core preferably has a diameter of at least 1.5 inches (about 38.1 mm). Preferably, the thickness of the intermediate layer is about 0.02-0.08 inch (0.508 mm-2.032 mm) and the combined thickness of the cover and the intermediate layer is about 0.1 inch (2.54 mm). Is less than. The core polybutadiene rubber composition contains at least about 2.2 pph of a halogenated organosulfur compound, preferably zinc pentachlorothiophenol.
Obviously, the invention disclosed herein has been sufficiently calculated to satisfy the objectives set forth above, but many modifications and embodiments may be devised by those skilled in the art. . Such modifications may include density modifiers, UV absorbers, hindered amine light stabilizers, optical brighteners, moisture barrier layers, and the like. In addition to its use in golf balls, the present invention can be used in other golf devices, for example, in golf club inserts. It is therefore intended that the appended claims not cover all such modifications as fall within the true spirit and scope of the invention.

1 shows a cross-sectional view of the golf ball of the present invention.

Claims (16)

  A golf ball comprising a core of at least one layer and a cover of at least one layer concentrically disposed about the core, wherein the cover comprises a segmented polyurethane elastomer. The segmented polyurethane elastomers are ionomers and their acid polymers, including highly neutralized polymers, polyolefins, polyacrylates, polyamides, polyphenylene oxides, polyisoprenes, block copoly (ether or ester-amide), block copoly (ether) Or ester-ester), polysulfone, reaction injection moldable thermoplastic and thermoset polymers, styrene-butadiene block copolymers and hydrogenated derivatives thereof, dynamically vulcanized ethylene-propylene rubber, polyvinylidene fluoride, acrylonitrile -From butadiene-styrene copolymer, epoxy resin, polystyrene, acrylic resin, polyethylene, polybutadiene, polyester, silicone-urethane or polycarbonate-urethane At least one member of a thermoplastic or thermosetting polymer blended, golf ball according to claim 1 which is selected from that group.   2. The golf ball of claim 1, wherein the segmented polyurethane elastomer comprises a surface modified end group.   The golf ball according to claim 1, wherein the golf ball further comprises at least one intermediate layer disposed between the cover and the core.   5. The golf ball according to claim 4, wherein at least one of the intermediate layers comprises an expanded elastomeric material.   5. The golf ball of claim 4, wherein at least one of the intermediate layers comprises a thermoplastic material having a flexural modulus of at least 50,000 psi.   The golf ball of claim 1, wherein the segmented polyurethane elastomer has a tensile strength greater than about 5,000 psi.   The golf ball of claim 1, wherein the segmented polyurethane elastomer has a tensile strength greater than about 68.9 MPa (about 10,000 psi).   The golf ball of claim 1, wherein the segmented polyurethane elastomer has an ultimate elongation of about 400-800%.   The golf ball of claim 1, wherein the segmented polyurethane elastomer has an initial modulus greater than about 2.0 MPa (about 300 psi).   The golf ball of claim 1, wherein the segmented polyurethane elastomer has a Shore D hardness of about 30-65.   The golf ball of claim 1, wherein the cover has a thickness of 0.508 mm to 3.175 mm (0.02 to 0.125 inches).   The golf ball of claim 1, wherein the golf ball has a compression of less than 120.   The golf ball of claim 1, wherein the core has a diameter of about 1.0 to about 1.62 inches.   A core of at least one layer, a cover of at least one layer concentrically arranged around the core, the cover having a Shore D hardness of 30 to 65, and at least one cover inserted between the cover and the core. A golf ball comprising two intermediate layers, wherein the cover comprises a segmented polyurethane elastomer having a surface modified end group.   16. The golf ball of claim 15, wherein the golf ball comprises a segmented polyurethane elastomer as a reaction product of a hydroxyl terminated polycarbonate, an aromatic diisocyanate and a low molecular weight diamine.

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