US20200197750A1

US20200197750A1 - Minimal surface golf ball components

Info

Publication number: US20200197750A1
Application number: US16/226,737
Authority: US
Inventors: Michael R. Madson
Original assignee: Acushnet Co
Current assignee: Acushnet Co
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-06-25
Also published as: JP2020099678A; JP7077291B2

Abstract

The present invention provides a novel golf ball construction including a structural core component based on a minimal surface design. The structural core component has an envelope shape and consists of a minimal surface and an interstitial space, the minimal surface and interstitial space being bounded by the envelope shape of the structural component. The minimal surface is a single continuous surface which does not intersect itself and has zero mean curvature.

Description

FIELD OF THE INVENTION

The present invention relates to golf ball components, particularly golf ball cores, based on a minimal surface design.

BACKGROUND OF THE INVENTION

Minimal surfaces are surfaces with zero mean curvature, also characterized as surfaces of minimal surface area for given boundary conditions. Uses for minimal surfaces have been studied in areas such as high rise construction, scaffolding design for tissue engineering, and mass transfer processes. For example, U.S. Patent Application Publication No. 2014/0014493 discloses mass transfer packing with a minimal surface which purportedly enables significantly improved performance for separation and mixing. Minimal surface structures have not previously been explored for use in golf balls.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball having a core that comprises a structural component having an envelope shape and consisting of a minimal surface and an interstitial space, the minimal surface and interstitial space being bounded by the envelope shape of the structural component. The minimal surface is a single continuous surface which does not intersect itself and has zero mean curvature.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGS. 1A and 1B illustrate a perspective view of a minimal surface bounded by an envelope shape according to an embodiment of the present invention;

FIGS. 2A and 2B illustrate a perspective view of a minimal surface bounded by an envelope shape according to another embodiment of the present invention;

FIGS. 3A and 3B illustrate perspective views of a minimal surface bounded by an envelope shape according to another embodiment of the present invention;

FIGS. 3C-3F are planar views of the minimal surface illustrated in FIGS. 3A and 3B;

FIGS. 4A and 4B illustrate perspective views of a triply periodic minimal surface bounded by an envelope shape according to an embodiment of the present invention;

FIG. 5 is a section view of a golf ball according to an embodiment of the present invention; and

FIG. 6 is a section view of a golf ball according to another embodiment of the present invention.

DETAILED DESCRIPTION

Golf balls of the present invention have a novel construction wherein the core comprises a structural component having an outer boundary defined by an envelope shape and consisting of a minimal surface and an interstitial space. A minimal surface is a surface that locally minimizes its area. The minimization of area within the confines of a given boundary allows for especially low density to envelope volume ratios, which, when used in golf ball cores, permits the weight of the ball to be more efficiently shifted to outer layers without sacrificing speed. Another advantage provided by minimal surfaces results from the absence of discontinuities, or sharp corners, in the single continuous surface of minimal surfaces, potentially allowing for improved durability relative to conventional non-spherical core components. Yet another potential advantage of using minimal surfaces in golf ball cores is high resilience regardless of orientation due to the multiple symmetrical axes that exist in minimal surfaces.
For purposes of the present disclosure, a “minimal surface” is a surface that is confined to an envelope shape and has the following properties.

- a) the surface is a single, continuous surface;
- b) the surface does not intersect itself;
- c) the surface is free of any discontinuities, except where the surface terminates at the boundary of the envelope shape; and
- d) the surface has zero mean curvature.

For purposes of the present disclosure, a “discontinuity” in the minimal surface refers to a sharp corner that may create a stress raiser. Thus, minimal surfaces of the present invention are free of sharp edges that are not located at the boundary of the envelope shape.
For purposes of the present disclosure, “zero mean curvature” means that the mean curvature of the minimal surface is zero at every point on the surface. Mean curvature is the average of the two principle curvatures. Principle curvatures are the maximum and minimum of the normal curvature at a given point on a surface. In other words, for each point on the surface, there is a point on the opposing side with equal and opposite curvature, such that the mean curvature for the entire surface is zero.
Optionally, the minimal surface is triply periodic, meaning, for purposes of the present invention, that the surface has a base unit that repeats periodically along three different axes. For purposes of the present disclosure, “base unit” refers to a base minimal surface structure that can be used to create a triply periodic minimal surface. The minimal surface of structural core components of the present invention can be a single base unit or multiple base units patterned along three axes to generate a triply periodic minimal surface.
The pure mathematical definition of a “surface” does not exist in three-dimensional space. Thus, for purposes of the present invention, the mathematical surfaces described herein are prescribed a particular thickness, t, in order to create a manufacturable component. In a particular embodiment, minimal surfaces of the present invention have a thickness, t, of from 0.001 inches to 0.030 inches. In another particular embodiment, the thickness of the minimal surface is constant, i.e., the thickness of the minimal surface is about equal at all points. For purposes of the present disclosure, the thickness of the minimal surface is constant if the thickness at any point on the minimal surface is no more than 0.002 inches different from the average thickness of the minimal surface. In another particular embodiment, the thickness of the minimal surface is non-constant.
The term “envelope” is used herein to refer to the boundary of a three-dimensional shape within which a minimal surface is restricted. When used herein in reference to a golf ball component, the “envelope shape” is the three-dimensional shape having the minimum volume that fully encompasses the minimal surface and, thus, defines the outer boundary of the structural component. The remaining volume of the envelope shape that encompasses the minimal surface is the interstitial space of the structural component. It should be understood that the boundary of the envelope shape is a reference boundary relating to the space within which the minimal surface and interstitial space of the structural core component are restricted, and is not necessarily a solid surface in the final golf ball. For example, the structural component of the core does not have a solid outer surface when the interstitial space is hollow or liquid-filled.
For example, FIG. 1A shows a minimal surface 10 confined to a cubic envelope shape, according to an embodiment of the present invention. FIG. 1B shows the minimal surface 10 of FIG. 1A and the cube 15 to which the minimal surface 10 is confined. Also shown in FIG. 1B is an interstitial space 18 bounded by the cube 15 to which the minimal surface 10 is confined. The minimal surface shown in FIGS. 1A and 1B is a single base unit.
FIG. 2A shows a minimal surface 20 confined to a spherical envelope shape, according to an embodiment of the present invention. FIG. 2B shows the minimal surface 20 of FIG. 2A and the sphere 25 to which the minimal surface 20 is confined. Also shown in FIG. 2B is an interstitial space 28 bounded by the sphere 25 to which the minimal surface 20 is confined. The minimal surface shown in FIGS. 2A and 2B is the single base unit of FIGS. 1A and 1B confined to a spherical envelope shape.
FIG. 3A shows a triply periodic minimal surface 30 confined to a cubic envelope shape, according to an embodiment of the present invention. FIG. 3B shows the triply periodic minimal surface 30 of FIG. 3A and the cube 35 to which the triply periodic minimal surface 30 is confined. Also shown in FIG. 3B is an interstitial space 38 bounded by the cube 35 to which the minimal surface 30 is confined.
FIGS. 3C-3E are a front view, a right side view, and a top view, respectively, of the triply periodic minimal surface 30 of FIGS. 3A and 3B. FIG. 3F is a planar view of the triply periodic minimal surface 30 illustrated in FIGS. 3A-3E, wherein the viewing plane is normal to an axis connecting the centroid of the cubic envelope shape to a vertex of the cubic envelope shape.
In the embodiment shown in FIGS. 3A-3F, the triply periodic minimal surface 30 is created using the minimal surface 10 of FIGS. 1A and 1B as a base unit and repeating the base unit along three different axes, the triply periodic minimal surface terminating at a cubic envelope shape.
FIGS. 4A and 4B are perspective views of a triply periodic minimal surface 40 confined to a spherical envelope shape, according to an embodiment of the present invention. In the embodiment shown in FIGS. 4A-4B, the triply periodic minimal surface 40 is created using the minimal surface 10 of FIGS. 1A and 1B as a base unit and repeating the base unit along three different axes, the triply periodic minimal surface terminating at a spherical envelope shape.
Many minimal surfaces are known, and the present invention is not meant to be limited to a particular minimal surface. Triply periodic minimal surfaces are particularly suitable, including, but not limited to, triply periodic surfaces having a base unit selected from Schoen's Gyroid (G) Surface, Schwarz's P Surface, Schwarz's D Surface, Schoen's Complementary D Surface, Schoen's F-RD Surface, Schoen's GW Surface, Schoen's I-WP Surface, Neovius's Surface, Schoen's Batwing Surface, Brakke's Pseudo-Batwing Surface, Lord and MacKay P3a Surface, Fisher-Koch S Surface, and hybrids thereof, such as Schoen's O,C-TO Surface hybrid of the P Surface and the I-WP Surface. The minimal surfaces shown in FIGS. 1A, 1B, 2A, 2B, 3A-3F, 4A, 4B, 5 and 6, are based on an approximation of Schoen's Gyroid (G) Surface, created using SolidWorks.
While the present invention is not meant to be limited to a particular minimal surface; bubbles are meant to be excluded. Bubbles are a well-known example of a minimal surface. Because some embodiments of conventional spherical golf ball cores are mathematically equivalent to a bubble, bubbles, i.e., spheres, are expressly excluded as a minimal surface of the present invention.
Non-limiting examples of suitable three-dimensional shapes for use as envelope shapes are spheres and regular shapes, such as cubes, octahedrons, cuboctahedrons, dodecahedrons, tetrahedrons, and icosahedrons, which have equal sides and equal interior angles.
The volume of the envelope shape is the “envelope volume.”
For purposes of the present disclosure, the “envelope volume ratio” is the ratio of the volume of the minimal surface, V_M, to the volume of the envelope shape, V_E, and is less than 1, or less than 0.50 or less than 0.25.
For purposes of the present disclosure, the “envelope surface area ratio” is the ratio of the surface area of the minimal surface, A_M, to the surface area of the envelope shape, A_E, and is either less than 1 or greater than 1 or greater than 2.
The interstitial space of the structural component can be hollow or filled. In embodiments of the present invention wherein the interstitial space is hollow, the golf ball includes at least one additional layer disposed about the structural component. Thus, in a particular embodiment, the golf ball comprises a structural component consisting of a minimal surface and a hollow interstitial space, a first layer surrounding the structural component, and optionally, one or more additional layers disposed about the first layer.
In embodiments of the present invention wherein the interstitial space of the structural component is filled, the material used to fill the space can terminate at or extend beyond the envelope shape of the structural component. In embodiments of the present invention wherein the composition of the interstitial space is bounded by the envelope shape of the structural component, the golf ball includes at least one additional layer disposed about the structural component. In embodiments of the present invention wherein the composition of the interstitial space extends beyond the envelope shape of the structural component such that the structural component is surrounded by a layer formed from the composition, the golf ball optionally includes one or more additional layers disposed about the layer formed from the composition.
In embodiments of the present invention wherein the material used to fill the interstitial space extends beyond the envelope shape that encompasses the structural component, the material terminates at an outer surface that can have the same shape or a different shape than the envelope shape.
Minimal surfaces for use in golf ball cores can be manufactured using rapid prototyping methods, including, but not limited to, continuous liquid interface printing methods, such as those disclosed, for example, in U.S. Pat. No. 10,016,661, the entire disclosure of which is hereby incorporated herein by reference, and conventional 3D printing methods. Materials suitable for forming the minimal surface include those that are capable of being used in such rapid prototyping methods, including light-curable polymerizable materials, such as sol-gel, polyesters, vinyl ethers, acrylates, methacrylates, polyurethanes, polyureas, bio-absorbable resins, silicones, epoxides, cyanate esters, hydrogels, investment casting resins, polycarbonates, and thiol-enes. Also suitable for forming the minimal surface are conventional golf ball materials, including those disclosed herein as suitable for forming core layers and cover layers.
In a particular embodiment, the minimal surface is formed from a ultraviolet (UV) light polymerizable resin comprising a photoinitiator and a mixture of light-curable oligomers and monomers. Preferably, the UV light polymerizable resin comprises a light-curable oligomer in an amount of 60 wt % or greater, based on the total weight of the resin. Particularly suitable oligomers include, but are not limited to, epoxides, urethanes, polyethers, polyesters, acrylics, and mixtures of two or more thereof, preferably functionalized by an acrylate. In a particular embodiment, the oligomer is selected from acrylated polyethers, acrylated polyesters, acrylated acrylics, polybutadiene dimethacrylate, and polybutadiene diacrylate. Non-limiting examples of commercially available acrylated oligomers that are suitable for use in the present invention include Laromer® PE 44F and Laromer® PE 8981 polyester acrylates, commercially available from BASF; Ebecryl™ chlorinated acrylated polyesters, commercially available from Allnex; and CN 301 polybutadiene dimethacrylate and CN 302 polybutadiene diacrylate, commercially available from Sartomer.
Preferably, the UV light polymerizable resin comprises a light-curable monomer in an amount of 20 wt % or greater, based on the total weight of the resin. Particularly suitable monomers for use in the UV light polymerizable resin include, but are not limited to, styrene monomers, N-vinylpyrrolidone monomers, and acrylic monomers. These monomers can help control the properties of the resin, such as cure speed, cross-link density, and viscosity. In a particular embodiment, the monomer is selected from acrylic monomers, such as pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), 1,6 hexanediol diacrylate (HODA), tripropylene glycol diacrylate (TRPGDA), triethylene glycol diacrylate (TREGDA), 2-ethylhexyl acrylate, vinyl acetate, butyl acrylate, dimethylaminoethyl acrylate, isobutoxymethyl acrylamide, and dimethylacrylamide. Non-limiting examples of commercially available acrylic monomers that are suitable for use in the present invention include TMPTA trimethylolpropane triacrylate and Ebecryl™ 40 tetraacrylate monomer, commerically available from Allnex.
Preferably, the UV light polymerizable resin comprises a photoinitiator in an amount of 3 wt % or greater, based on the total weight of the resin, and is cured using UV light radiation. However, the resin may also be cured using other light and energy curing sources, including, but not limited to, visible light and electron beam. Suitable photoinitiators include anionic and cationic photoinitiators, such as styrenic compounds, vinyl ethers, N-vinyl carbazoles, lactones, lactams, cyclic ethers, cyclic acetals, cyclic siloxanes, benzoin ethers, and benzophenone. In a particular embodiment, the photoinitiator is selected from 1-hydroxy-cyclohexyl-phenyl-ketone and a blend of trimethylbenzophenone, polymeric hydroxy ketone, and trimethylbenzoyldiphenyl phosphine oxide. Non-limiting examples of commercially available photoinitiators that are suitable for use in the present invention include Irgacure® 184 1-hydroxy-cyclohexyl-phenyl-ketone photoinitiator and Irgacure® 819 phenyl bis (2,4,6-trimethyl benzoyl) phosphine oxide photoinitiator, commercially available from Ciba Specialty Chemicals; and Esacure KTO-46 blend of trimethylbenzophenone, polymeric hydroxy ketone, and trimethylbenzoyldiphenyl phosphine oxide, commercially available from IGM resins.
Various other thermoplastic and thermoset materials, fillers, and other additives, such as inhibitors, surfactants, waxes, cure accelerators, defoaming agents, pigments, dispersing agents, optical brighteners, UV light stabilizers, UV absorbers, adhesion promoters, and the like, may be added to the resin. Inhibitors may be used to retard or stop undesirable polymerization of the oligomers and monomers.
The interstitial space of the structural component may be filled with any suitable liquid, foamed, or unfoamed solid composition. Particularly suitable compositions for filling the interstitial space of the structural component include, but are not limited to, foamed highly neutralized polymers, such as those disclosed in U.S. Pat. No. 7,708,654 to Sullivan et al., the entire disclosure of which is hereby incorporated herein by reference; foamed polyurethanes, such as those disclosed in U.S. Pat. No. 9,254,422 to Sullivan et al., the entire disclosure of which is hereby incorporated herein by reference; castable polyurethanes, such as those disclosed in U.S. Pat. No. 9,254,422 to Sullivan et al.; the entire disclosure of which is hereby incorporated herein by reference; and rubbers.
In embodiments of the present invention wherein the golf ball comprises one or more additional layers disposed about the structural component (in addition to the optional layer formed from the composition of the interstitial space if such composition extends beyond the envelope shape of the structural component), each additional layer may be formed from any suitable golf ball composition. Particularly suitable core layer materials include, but are not limited to, thermosetting materials, such as styrene butadiene, polybutadiene, isoprene, polyisoprene, and trans-isoprene; thermoplastics, such as ionomer resins, polyamides and polyesters; and thermoplastic and thermosetting polyurethane and polyureas. Particularly preferred core compositions are thermosetting rubber compositions comprising a base polymer, an initiator agent, a coagent and/or a curing agent, and optionally one or more of a metal oxide, metal fatty acid or fatty acid, antioxidant, soft and fast agent, fillers, and additives. Suitable base polymers include natural and synthetic rubbers including, but not limited to, polybutadiene, polyisoprene, ethylene propylene rubber (“EPR”), styrene-butadiene rubber, styrenic block copolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” is isobutylene, and “B” is butadiene), butyl rubber, halobutyl rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, metallocene-catalyzed elastomers and plastomers, copolymers of isobutylene and para-alkylstyrene, halogenated copolymers of isobutylene and para-alkylstyrene, acrylonitrile butadiene rubber, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, polyalkenamers, and combinations of two or more thereof. Suitable initiator agents include organic peroxides, high energy radiation sources capable of generating free radicals, C—C initiators, and combinations thereof. Suitable coagents include, but are not limited to, metal salts of unsaturated carboxylic acids; unsaturated vinyl compounds and polyfunctional monomers (e.g., trimethylolpropane trimethacrylate); phenylene bismaleimide; and combinations thereof. Suitable curing agents include, but are not limited to, sulfur; N-oxydiethylene 2-benzothiazole sulfenamide; N,N-di-ortho-tolylguanidine; bismuth dimethyldithiocarbamate; N-cyclohexyl 2-benzothiazole sulfenamide; N,N-diphenylguanidine; 4-morpholinyl-2-benzothiazole disulfide; dipentamethylenethiuram hexasulfide; thiuram disulfides; mercaptobenzothiazoles; sulfenamides; dithiocarbamates; thiuram sulfides; guanidines; thioureas; xanthates; dithiophosphates; aldehyde-amines; dibenzothiazyl disulfide; tetraethylthiuram disulfide; tetrabutylthiuram disulfide; and combinations thereof. Suitable types and amounts of base polymer, initiator agent, coagent, filler, and additives are more fully described in, for example, U.S. Pat. Nos. 6,566,483, 6,695,718, 6,939,907, 7,041,721 and 7,138,460, the entire disclosures of which are hereby incorporated herein by reference. Particularly suitable diene rubber compositions are further disclosed, for example, in U.S. Patent Application Publication No. 2007/0093318, the entire disclosure of which is hereby incorporated herein by reference.
Particularly suitable cover layer materials include, but are not limited to:

- a) polyurethanes, polyureas, and hybrids of polyurethane and polyurea;
- b) E/X- and E/X/Y-type ionomers, wherein E is an olefin (e.g., ethylene), X is a carboxylic acid (e.g., acrylic, methacrylic, crotonic, maleic, fumaric, or itaconic acid), and Y is a softening comonomer (e.g., vinyl esters of aliphatic carboxylic acids wherein the acid has from 2 to 10 carbons, alkyl ethers wherein the alkyl group has from 1 to 10 carbons, and alkyl alkylacrylates such as alkyl methacrylates wherein the alkyl group has from 1 to 10 carbons), such as Surlyn® ionomer resins and DuPont® HPF 1000 and HPF 2000, commercially available from E. I. du Pont de Nemours and Company, Iotek® ionomers, commercially available from ExxonMobil Chemical Company, Amplify® IO ionomers of ethylene acrylic acid copolymers, commercially available from The Dow Chemical Company, and Clarix® ionomer resins, commercially available from A. Schulman Inc.;
- c) polyisoprene;
- d) polyoctenamer, such as Vestenamer® polyoctenamer, commercially available from Evonik Industries;
- e) polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene;
- f) rubber-toughened olefin polymers; non-ionomeric acid copolymers, e.g., (meth)acrylic acid, which do not become part of an ionomeric copolymer;
- g) plastomers;
- h) flexomers;
- i) styrene/butadiene/styrene block copolymers;
- j) styrene/ethylene-butylene/styrene block copolymers;
- k) polybutadiene;
- l) styrene butadiene rubber;
- m) ethylene propylene rubber;
- n) ethylene propylene diene rubber;
- o) dynamically vulcanized elastomers;
- p) ethylene vinyl acetates;
- q) ethylene (meth) acrylates;
- r) polyvinyl chloride resins;
- s) polyamides, amide-ester elastomers, and copolymers of ionomer and polyamide, including, for example, Pebax® thermoplastic polyether and polyester amides, commercially available from Arkema Inc;
- t) crosslinked trans-polyisoprene;
- u) polyester-based thermoplastic elastomers, such as Hytrel® polyester elastomers, commercially available from E. I. du Pont de Nemours and Company, and Riteflex® polyester elastomers, commercially available from Ticona;
- v) polyurethane-based thermoplastic elastomers, such as Elastollan® polyurethanes, commercially available from BASF;
- w) synthetic or natural vulcanized rubber;
- x) and combinations thereof.

Compositions comprising an ionomer or a blend of two or more E/X- and E/X/Y-type ionomers are particularly suitable conventional cover materials. Preferred E/X- and E/X/Y-type ionomeric cover compositions include:

- (a) a composition comprising a “high acid ionomer” (i.e., having an acid content of greater than 16 wt %), such as Surlyn 8150®;
- (b) a composition comprising a high acid ionomer and a maleic anhydride-grafted non-ionomeric polymer (e.g., Fusabond® functionalized polymers). A particularly preferred blend of high acid ionomer and maleic anhydride-grafted polymer is a 84 wt %/16 wt % blend of Surlyn 8150® and Fusabond®. Blends of high acid ionomers with maleic anhydride-grafted polymers are further disclosed, for example, in U.S. Pat. Nos. 6,992,135 and 6,677,401, the entire disclosures of which are hereby incorporated herein by reference;
- (c) a composition comprising a 50/45/5 blend of Surlyn® 8940/Surlyn® 9650/Nucrel® 960, preferably having a material hardness of from 80 to 85 Shore C;
- (d) a composition comprising a 50/25/25 blend of Surlyn® 8940/Surlyn® 9650/Surlyn® 9910, preferably having a material hardness of about 90 Shore C;
- (e) a composition comprising a 50/50 blend of Surlyn® 8940/Surlyn® 9650, preferably having a material hardness of about 86 Shore C;
- (f) a composition comprising a blend of Surlyn® 7940/Surlyn® 8940, optionally including a melt flow modifier;
- (g) a composition comprising a blend of a first high acid ionomer and a second high acid ionomer, wherein the first high acid ionomer is neutralized with a different cation than the second high acid ionomer (e.g., 50/50 blend of Surlyn® 8150 and Surlyn® 9150), optionally including one or more melt flow modifiers such as an ionomer, ethylene-acid copolymer or ester terpolymer; and
- (h) a composition comprising a blend of a first high acid ionomer and a second high acid ionomer, wherein the first high acid ionomer is neutralized with a different cation than the second high acid ionomer, and from 0 to 10 wt % of an ethylene/acid/ester ionomer wherein the ethylene/acid/ester ionomer is neutralized with the same cation as either the first high acid ionomer or the second high acid ionomer or a different cation than the first and second high acid ionomers (e.g., a blend of 40-50 wt % Surlyn® 8140, 40-50 wt % Surlyn® 9120, and 0-10 wt % Surlyn® 6320).

Surlyn 8150®, Surlyn® 8940, and Surlyn® 8140 are different grades of E/MAA copolymer in which the acid groups have been partially neutralized with sodium ions. Surlyn® 9650, Surlyn® 9910, Surlyn® 9150, and Surlyn® 9120 are different grades of E/MAA copolymer in which the acid groups have been partially neutralized with zinc ions. Surlyn® 7940 is an E/MAA copolymer in which the acid groups have been partially neutralized with lithium ions. Surlyn® 6320 is a very low modulus magnesium ionomer with a medium acid content. Nucrel® 960 is an E/MAA copolymer resin nominally made with 15 wt % methacrylic acid. Surlyn® ionomers, Fusabond® polymers, and Nucrel® copolymers are commercially available from E. I. du Pont de Nemours and Company.
Suitable E/X- and E/X/Y-type ionomeric materials are further disclosed, for example, in U.S. Pat. Nos. 6,653,382, 6,756,436, 6,894,098, 6,919,393, and 6,953,820, the entire disclosures of which are hereby incorporated by reference.
Suitable polyurethanes, polyureas, and blends and hybrids of polyurethane/polyurea are further disclosed, for example, in U.S. Pat. Nos. 5,334,673, 5,484,870, 6,506,851, 6,756,436, 6,835,794, 6,867,279, 6,960,630, and 7,105,623; U.S. Patent Application Publication No. 2009/0011868; and U.S. Patent Application No. 60/401,047, the entire disclosures of which are hereby incorporated herein by reference. Suitable polyurethane-urea materials include polyurethane/polyurea blends and copolymers comprising urethane and urea segments, as disclosed in U.S. Patent Application Publication No. 2007/0117923, the entire disclosure of which is hereby incorporated herein by reference.
Cover compositions may include one or more filler(s), such as titanium dioxide, barium sulfate, etc., and/or additive(s), such as coloring agents, fluorescent agents, whitening agents, antioxidants, dispersants, UV absorbers, light stabilizers, plasticizers, surfactants, compatibility agents, foaming agents, reinforcing agents, release agents, and the like.
In a particular embodiment, the present invention is directed to a golf ball consisting essentially of a structural core component and a surrounding layer, wherein the structural core component has an outer boundary defined by an envelope shape and consists of a minimal surface and an interstitial space, wherein the interstitial space is filled with a composition that extends beyond the envelope shape of the structural core component such that the composition of the interstitial space forms the surrounding layer.
In another particular embodiment, the present invention is directed to a golf ball comprising a structural core component, a surrounding layer, and an outer cover layer. The structural core component has an outer boundary defined by an envelope shape and consists of a minimal surface and an interstitial space. The interstitial space is filled with a composition that extends beyond the envelope shape of the structural core component such that the composition of the interstitial space forms the surrounding layer. The golf ball optionally includes one or more intermediate layers disposed between the surrounding layer and the outer cover layer.
In another particular embodiment, the present invention is directed to a golf ball consisting essentially of a structural core component and an outer cover layer disposed about the structural core component, wherein the structural core component has an outer boundary defined by an envelope shape and consists of a minimal surface and an interstitial space, wherein the interstitial space is hollow or is filled with a composition that is bounded by the envelope shape of the structural core component.
In another particular embodiment, the present invention is directed to a golf ball comprising a structural core component, one or more intermediate layers, and an outer cover layer. The structural core component has an outer boundary defined by an envelope shape and consists of a minimal surface and an interstitial space, wherein the interstitial space is hollow or is filled with a composition that is bounded by the envelope shape of the structural core component. In a particular aspect of this embodiment, the interstitial space is filled with a polyurethane foam.

EXAMPLES

It should be understood that the examples below are merely illustrative of particular embodiments of the present invention, and are not to be construed as limiting the invention, the scope of which is defined by the appended claims.
In Examples 1 and 2 below, the minimal surface corresponds to the triply periodic minimal surface 40 of FIGS. 4A and 4B. In a particular aspect of the embodiments shown in FIGS. 4A, 4B, 5, and 6, the spherical envelope shape has:

- a diameter of about 1.55 inches,
- a surface area (A_E) of about 7.548 in², and
- an envelope volume (V_E) of about 1.950 in³;
  and the minimal surface has:
- a constant thickness of about 0.009 inches,
- a surface area (A_M) of about 23.733 in², and
- a volume (V_M) of about 0.123 in³.
  Thus, in a particular aspect of the embodiments shown in FIGS. 4A, 4B, 5, and 6, the envelope volume ratio is about 0.063 and the envelope surface area ratio is about 3.14.

Example 1

FIG. 5 illustrates an example of a golf ball construction according to an embodiment of the present invention. In particular, FIG. 5 shows a section view of a golf ball 50, wherein the golf ball consists of a structural core component and a surrounding layer. The structural core component has an outer boundary defined by a spherical envelope shape and consists of a minimal surface 51 and an interstitial space 55. As shown in FIG. 5, the interstitial space is filled with a composition that extends beyond the spherical envelope shape of the structural core component such that the composition of the interstitial space forms the surrounding layer and serves as the dimpled outer surface of the golf ball.

Example 2

FIG. 6 illustrates an example of a golf ball construction according to another embodiment of the present invention. In particular, FIG. 6 shows a section view of a golf ball 60, wherein the golf ball comprises a structural core component consisting of a minimal surface 51 and an interstitial space 52, an optional intermediate layer 53, and a cover 54. The structural core component has an outer boundary defined by a spherical envelope shape. The interstitial space is hollow or is filled with a composition that is bounded by the spherical envelope shape of the structural core component. While shown in FIG. 6 as a single layer, the cover 54 may be a single-, dual-, or multi-layer cover.
When numerical lower limits and numerical upper limits are set forth herein, it is contemplated that any combination of these values may be used.
All patents, publications, test procedures, and other references cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.
While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein, but rather that the claims be construed as encompassing all of the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those of ordinary skill in the art to which the invention pertains.

Claims

1. A golf ball comprising a core, wherein the core comprises a structural component having an outer boundary defined by an envelope shape; wherein the structural component consists of a minimal surface and an interstitial space; and wherein the minimal surface is a single continuous surface which does not intersect itself and has zero mean curvature, excluding spheres.

2. The golf ball of claim 1, wherein the minimal surface has a constant thickness.

3. The golf ball of claim 1, wherein the envelope shape of the structural component is a sphere having a diameter of from 0.25 inches to 1.64 inches.

4. The golf ball of claim 1, wherein the interstitial space is filled with a foamed or unfoamed solid composition, and wherein the composition of the interstitial space extends beyond the outer boundary of the structural component such that the structural component is surrounded by a layer formed from the composition.

5. The golf ball of claim 4, wherein the golf ball consists essentially of the structural component and the layer surrounding the structural component, the layer surrounding the structural component being a dimpled outer cover layer of the golf ball.

6. The golf ball of claim 5, wherein the composition filling the interstitial space and forming the layer surrounding the structural component is selected from the group consisting of polyurethanes, polyureas, and polyurethane-urea hybrids and blends.

7. The golf ball of claim 5, wherein the composition filling the interstitial space and forming the layer surrounding the structural component is an ionomer composition.

8. The golf ball of claim 4, wherein the golf ball comprises the structural component, the layer surrounding the structural component, and a cover.

9. The golf ball of claim 1, wherein the interstitial space is filled with a composition; the composition of the interstitial space is bounded by the outer boundary of the structural component; and the golf ball comprises one or more additional layers disposed about the core.

10. The golf ball of claim 9, wherein the composition is a foamed solid composition.

11. The golf ball of claim 9, wherein the composition is an unfoamed solid composition.

12. The golf ball of claim 9, wherein the composition is a liquid.

13. The golf ball of claim 1, wherein the interstitial space is hollow, and wherein the golf ball comprises one or more additional layers disposed about the core.

14. The golf ball of claim 1, wherein the envelope shape of the structural component is selected from the group consisting of spheres, cubes, octahedrons, cuboctahedrons, dodecahedrons, tetrahedrons, and icosahedrons.

15. The golf ball of claim 1, wherein the minimal surface is triply periodic.

16. The golf ball of claim 1, wherein the ratio of the volume of the minimal surface (V_M) to the volume of the envelope shape (V_E) is less than 1.

17. The golf ball of claim 1, wherein the ratio of the volume of the minimal surface (V_M) to the volume of the envelope shape (V_E) is less than 0.50.

18. The golf ball of claim 1, wherein the ratio of the volume of the minimal surface (V_M) to the volume of the envelope shape (V_E) is less than 0.25.

19. The golf ball of claim 1, wherein the ratio of the surface area of the minimal surface (A_M) to the surface area of the envelope shape (A_E) is less than 1.

20. The golf ball of claim 1, wherein the ratio of the surface area of the minimal surface (A_M) to the surface area of the envelope shape (A_E) is greater than 1.

21. The golf ball of claim 1, wherein the ratio of the surface area of the minimal surface (A_M) to the surface area of the envelope shape (A_E) is greater than 2.