Patent Application
20200197750
The present invention relates to golf ball components, particularly golf ball cores, based on a minimal surface design.
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.
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.
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:
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.
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,
In the embodiment shown in
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
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, VM, to the volume of the envelope shape, VE, 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, AM, to the surface area of the envelope shape, AE, 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:
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:
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.
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
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.
