Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/005—Cores
  • A63B37/0051—Materials other than polybutadienes; Constructional details
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/007—Characteristics of the ball as a whole
  • A63B37/0072—Characteristics of the ball as a whole with a specified number of layers
  • A63B37/0073—Solid, i.e. formed of a single piece

Definitions

• the present invention relates to a one-piece solid golf ball.
• Golf balls are classified as either wound or solid.
• the traditional wound golf ball has a complex structure consisting of rubber threads wound around the center of the ball. The process for making such a ball is time-consuming and expensive.
• Solid golf balls are classified as one-piece, two-piece or multi-layer.
• the one-piece golf ball consists of a single structure, the two-piece golf ball has a solid core covered with a cover and the multi-layer ball has three or more layers with an intermediate layer between the core and the cover.
• Most golf balls are formed from polymerized butadiene.
• the polybutadiene elastomer is crosslinked by a crosslinking agent which is a rather large quantity of a zinc salt of acrylic or methacrylic acid.
• a crosslinking agent which is a rather large quantity of a zinc salt of acrylic or methacrylic acid.
• An optimal crosslinker would increase hardness without decreasing resilience.
• the zinc salts of methacrylic and acrylic acids have shown great promise as crosslinkers for butadiene in the manufacture of solid golf balls, but so far no suitable one-piece golf ball for play by tournament caliber golfers has been made from these materials.
• Golf ball compounds crosslinked by acrylic acid zinc salts have generally demonstrated superior characteristics in terms of resilience but tend to be less durable.
• Ball forming compounds crosslinked by methacrylic acid zinc salts produce a ball of superior durability but at the expense of resilience. The following discussion of prior art illustrates these points.
• an improved golf ball can be made from a rubber composition containing zinc acrylate coated with a fatty acid such as stearic acid whereby the golf ball exhibits proper hardness, good impact resilience and good sound and feel when hit.
• a fatty acid such as stearic acid
• Another characteristic of this type of rubber composition is that it creates good roll workability and dipersability of rubber additives.
• Isaac et al Pat. No. 4,770,422 discloses an improved golf ball which is durable with good playing characteristics such as good initial velocity.
• the composition from which this ball is formed comprises polybutadiene crosslinked by zinc diacrylate whereby the amount of free radical initiator is substantially below that typically used in the past. This free radical initiator is necessary to promote the crosslinking reaction.
• Tominaga et al Pat. No. 4,556,220 discloses a golf ball which shows markedly superior rebound performance, durability and flight carry characteristics. This is achieved by forming the ball from polysulfide type compounds which regulate the molecular weight of the chains which result from crosslinking by regulating the length of such chains.
• Llort et al Pat. No. 4,714,607 teaches that a better golf ball is made by using a small amount of zinc diacrylate to crosslink polybutadiene. Zinc diacrylate is used as a first crosslinker and zinc dimethacrylate is used as a second crosslinker. The result is a golf ball with higher initial velocity and higher compression. Natural rubber can be added to improve durability.
• Reiter et al Pat. No. 4,688,801 teaches that a one-piece golf ball can be made with improved compression and fracture strength while the desired rebound, click and feel characteristics are maintained.
• a coagent comprising (i) admixture of a polyvalent metal salt of an unsaturated acid and an organic filler or (ii) a reaction product obtained by reaction of an unsaturated carboxylic acid with an organic filler followed by further reaction with a polyvalent metal compound in the presence of said unsaturated carboxylic acid where such coagent functions as a crosslinking agent with the polybutadiene elastomer.
• compositions for forming one-piece solid golf balls as well as forming the cores of two-piece golf balls.
• compositions of the present invention are applicable to solid one-piece golf balls and the cores of two-piece golf balls.
• the present invention is a composition for making a solid one-piece golf ball with a butadiene base which is crosslinked by a methacrylic acid zinc salt.
• the resulting product is a one-piece golf ball with outstanding performance which possesses both resilience and durability and which can be reproduced accurately and economically.
• This type of golf ball is suitable for play by tournament caliber golfers.
• the material comprising the composition can be used to form the core of a two-piece or multi-layer golf ball.
• a principal object of the present invention is to provide a novel composition which will produce a superior one-piece golf ball and a superior core for a multi-piece golf ball.
• Another object of the present invention is to provide a one-piece golf ball with outstanding resilience and durability characteristics.
• Yet another object of the present invention is to provide a process for producing one-piece golf balls which produces such balls economically and produces balls of the same consistent quality.
• Yet a further object of the present invention is to provide a composition for producing a one-piece golf ball that is suitable for play by tournament caliber golfers.
• All embodiments of the invention involve a composition which includes a polybutadiene crosslinked with a methacrylic acid zinc salt manufactured under the tradename Z-Max MA.
• This zinc salt is present in the range of 20 to 70 parts by weight per 100 parts of rubber to be used in formulating the solid one-piece golf ball and the core of the two-piece golf ball.
• the term rubber is intended to include a major portion of polybutadiene and may include minor portions of other polymers such as natural rubber, polyisoprene rubber, styrene butadiene rubber, ethylene propylene rubber and nitrile elastomers. In all embodiments, the rubber component must include at least 75% by weight of polybutadiene.
• the result of using the composition of the present invention in forming golf balls is a golf ball with outstanding performance.
• Such golf ball's improved characteristics include resilience, durability and economical reproducibility.
• the key feature of the present invention is the methacrylic acid zinc salt used to crosslink the butadiene.
• This zinc salt is unique in that its crosslinking energy is in the same order as the energy in commercially acceptable zinc salt made from acrylic acid, yet the golf ball produced from this salt cross-linked with polybutadiene is superior to commercially available balls.
• Methacrylic acid zinc salt is traditionally made by reacting methacrylic acid with zinc oxide.
• the reaction by which the zinc salt is produced is run in an abundance of air with 10% more than the stoichiometric amount needed of zinc oxide.
• the introduction of oxygen into the reaction prevents polymerization of the methacrylic acid during mixing with polybutadiene rubber.
• the zinc salt and the polybutadiene are blended in a roll mill producing a corrugated surface on one side of the product. This high radiating area keeps the temperature down and thus delays curing until the molding step.
• the temperature is preferably kept down to 75° C which is below polymerization temperature. As a result, polymerization and curing takes place during the molding step and not during the mixing step.
• the methacrylic acid zinc salt is prepared by introducing a charge of 44 pounds of zinc oxide to 85 pounds of methacrylic acid along with .25 pounds of stearic acid. 20 ml. of sulfuric acid is added as a catalyst. Prior to reaction, the zinc oxide and the stearic acid are dispersed in a solvent which contains heptane and
• 1,1,1-trichloroethane in about equal parts by volume and has a specific gravity of about .98.
• the methacrylic acid and sulfuric acid are added into a rotary vacuum drier and heated to 85-90°C.
• the solvents including the zinc oxide are then added to the drier.
• a one second blast of air is bled into the evacuated drier system at 30 second intervals to prevent polymerization of the zinc salt.
• the solvents and water of reaction are substantially removed by vacuum and the resulting product is a solid methacrylic acid zinc salt.
• the zinc salt is further dried and then reduced to particle size of 1-30 microns.
• This salt is currently manufactured by Yardley Ball Corporation, Milton, Florida, under the name Z-Max MA (Z-Max) and is referred to herein by that name.
• Comparative Examples 1-6 and 8-12 further describe and define the present invention.
• the salts compared with Z-Max are Sartomer 365 manufactured under this tradename by Sartomer Co., Inc., Exton, Pennsylvania and ReactRite manufactured under this tradename by Rockland React-Rite, Inc., Cartersville, Georgia.
• Two different samples of Z-Max were analyzed; one sample was manufactured in the old Yardley Ball Corporation plant in Pennsylvania and the other sample was manufactured in the new, currently operating Florida plant.
• the Pennsylvania sample represents Z-Max which has aged before curing and thus golf balls produced from it would be less resilient and thus less desirable.
• Z-Max should preferably be used, i.e., cross-linked with polybutadiene, within a week of production
• Examples 1-6 and 8-12 show that many features distinguish Z-Max and the polybutadiene cured with it from other commercially available zinc methacrylate.
• Z-Max has a higher zinc content and fresh Z-Max has a higher exothermic heat of polymerization.
• the x-ray diffraction pattern of Z-Max shows a stronger peak between 11 and 12 degrees and the particle sizes of Z-Max are the smallest of the group analyzed.
• the FTIR spectrum of Z-Max has more prominent CO crystalline peaks and the Z-Max samples had the highest solubility in xylene.
• the heat of curing is highest for the fresh z-MAx sample and polybutadiene cured with Z-Max has the highest Shore Hardness.
• Z-Max samples have lower swell indices than the other samples tested.
• Examples 1-6 shown below, provide the results of: 1) elemental analysis 2) differential scanning calorimetry 3) X-ray diffraction 4) microscopic examination 5) Fourier transform infrared spectroscopy and 6) xylene solubility.
• the analysis for zinc content in the samples was carried out by plasma analysis.
• the samples were also vacuum dried and analyzed for zinc, carbon and hydrogen at Galbraith Laboratories, Inc., (GLI) in Knoxville, Tennessee. The results are shown below.
• the heat of reaction by thermal analysis in known in the art to correlate with chemical reactivity in curing polybutadiene.
• Each sample was analyzed using a DuPont 910 Differential Scanning Calorimeter (DSC) with a 20° C/minute oven ramp, nitrogen atmosphere to 300 C in hermetically sealed pans.
• DSC Differential Scanning Calorimeter
• Each sample showed an exothermic peak due to heat of polymerization.
• the peak temperature in degrees centigrade and the heat of polymerization in joules per gram (J/g) were recorded.
• the older Z-Max sample also showed an endothermic heat of melting, apparently of a crystalline species formed on storage. It is noted that the structure of the cured polymer is influenced by the rate of cooling.
• the dry powders were each pressed in an aluminium frame.
• the diffraction patterns with CuK alpha radiation show no zinc oxide left in the samples.
• the ReactRite sample clearly has the largest amorphous phase and fewer crystals of one of the phases shared by the other two samples.
• the Z-Max and Sartomer samples appeared to contain mostly crystals and all samples had at least four crystalline planes.
• the Sartomer sample had particularly strong bands in the peaks at 9 to 10 and at 10 to 11 degrees and showed the most complicated crystalline pattern.
• an X-ray spectrum was run on a known zinc acrylate and compared to a methacrylate sample.
• the various zinc methacrylate samples were examined unde the microscope at 150 and 300 x magnification.
• the Z-Max particles were the smallest and most rounded, the Sartomer particles were the largest and constituted highly crystalline acicular flat planes.
• the ReactRite particles in xylene showe birefringence, suggesting a transition between amorphous and crystalline forms.
• Microscopy Microns Usually 3-10 1-5 5-25 5-200 Dia. Up to 35 Up to 200
• the finer particle size of the Z-Max samples corresponds with larger surface area for increased reactivity.
• the Florida Z-Max appeared to be less completely crystalline than the Sartomer.
• the particle sizes of the Z-Max were much smaller than those of the two other salts.
• the Sartomer sample appeared to be highly crystalline, in agreement with x-ray observation.
• the ReactRite sample had a mixture of acicular crystals and irregular roundish amorphous looking particles.
• a known Sartomer zinc acrylate was examined microscopically and compared to methacrylate.
• the FL Z-Max had about 10% more insoluble material than the PA Z-Max sample.
• the ash contents of PA Z-Max corresponded to between 29 and 30% zinc for both the soluble and insoluble phases.
• the FL Z-Max had similar results.
• the soluble portion ash content corresponded to 32% zinc and the insoluble portion to 26%.
• butadiene rubber that is cis-1,4 polybutadiene rubber
• Natural rubber for example, may be added to lower modulus and improve durability.
• methacrylic acid zinc salt constituent and the free radical or peroxide initiator numerous other ingredients may be incorporated into the solid ball compound.
• the composition usually contains fillers such as zinc oxide, barium sulfate, lead oxide, basic lead silicate, or the like, used singularly or in combination, to control the weight of the ball.
• additives may include: magnesium oxide, calcium carbonate as fillers and/or acid acceptors; mildly reinforcing fillers and/or nucleating agents such as silicas, carbon blacks, clays and the like; silanes and/or titanates as bonding and/or dispersing agents; antioxidants for improving process, heat and shelf aging properties; co-curing agents such as HVA-2, TMPTA, TMPTMA and the like; cure modifying agents such as sulfur and sulfur bearing compounds; granular or powdered high molecular weight polymeric materials as impact modifiers ' ; pigments and other ingredients for imparting various characteristics known by those skilled in the art of rubber compounding for golf balls.
• a suitable kneader, mixer or blender such as a roll mill or a Banbury mixer is then kneaded by a suitable kneader, mixer or blender such as a roll mill or a Banbury mixer.
• the rubber composition is molded using, for instance, heat pressure molding.
• a one-piece golf ball is prepared by heat-pressure molding the rubber composition into a ball having the size suitable for a golf ball.
• a two-piece golf ball is prepared by heat-pressure molding the rubber composition in a core mold having a suitable size to from a solid core and covering the core with a suitable cover.
• the cover can be prepared from compositions comprising, for instance, an ionomer resin as a main component and optionally a filler or coloring agent such as a titanium dioxide or zinc oxide.
• the solid core is covered with two covers previously molded in the form of a hemispherical shell and is then heat-pressure molded to fuse the two shells together to give a finished golf ball.
• Injection molding is
• composition of the present invention comprises high cis polybutadiene as the primary elastomer, Z-Max MA crosslinker in the range of between 20 to 70 parts, based on 100 parts of elastomer, basic lead silicate as filler-for-weight in the range of 5 to 15 parts, titanium dioxide pigment in the range of 0 to 15 parts, magnesium oxide acid acceptor in the range of 0 to 5 parts, Agerite Resin D antioxidant in the range of 0 to 2 parts, CAPOW KR 9S/H titanate in the range of 0 to 2 parts, Vul Cup R peroxide initiator in the range of 0.1 to 3 parts, and HVA-2 co-curing agent in the range of 0 to 2 parts.
• the compound is mixed at a temperature of 20 to 150°C in a Banbury mixer or a roll mill, then molded for 20 minutes at 175° C in a 1.727" golf ball mold.
• Comparative Examples 8-12 which appear below show the differences between the conventional salt-polybutadiene compositions and the Z-Max-polybutadiene compositions.
• the compositions were prepared in accordance with the teachings of present invention. The following analyses were performed: 1) heats of crystallizing and curing rubbers 2) exothermic recrystallization heat of cured samples 3) shore hardness and 4) swell index.
• the samples in the compound with rubber were cured in the DSC and the heats of crystallizing and curing of the rubbers were measured. This important exothermic heat was determined at 20° C/minute. The preceding crystallization exotherms were determined at both 5 and 20 C.
• React/Rite 7.64 The samples were close in heat of crystallization except for cured ReactRite which was significantly lower. This may be due to a less desirable form of cross-linking, such as the carbon-carbon bonds formed by peroxides, especially when zinc methacrylate is absent or less active.
• Shore hardness measurements were performed on all samples. Each molding was measured after aging for at least five days. The five measurements were at least 0.5 inch in from the edge as prescribed by ASTM. Averages of the measurements were taken and are shown below.
• the swell index was measured for each sample. This index represents the equilibrium weight of toluene absorbed by a cured rubber divided by the initial weight of the rubber. For example, an uptake of 69% is a swell index of 0.69. Parts of the moldings described above were weighed into an excess of freshly opened scintillation grade toluene and observed over four days of aging. Each day the swollen rubber samples were blotted and weighed in grams. The following results may vary in the last figure due to variability in blotting technique. WEIGHTS OF POLYBUTADIENE WITH TOLUENE
• the solvent uptake was 69 weight percent toluene for the PA Z-Max, 106% for the FL Z-Max, 115% for Sartomer and 136% for ReactRite. This difference indicates, that the polybutadiene cured with Z-Max was more resistant to solvent and therefore more cross-linked than the polybutadiene cured with the other salts.

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• 1991
  • 1991-04-04 WO PCT/US1991/000861 patent/WO1992007631A1/en not_active Application Discontinuation
  • 1991-04-04 DE DE0560798T patent/DE560798T1/de active Pending
  • 1991-04-04 AU AU89179/91A patent/AU8917991A/en not_active Abandoned
  • 1991-04-04 EP EP91920097A patent/EP0560798A1/de not_active Ceased
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