FR2574419A1 - COPOLYMER MOLDING COMPOSITION FOR GOLF BALL ENVELOPE, AND ENVELOPE AND GOLF BALL OBTAINED - Google Patents

Abstract

COMPOSITION OF COPOLYMER TO BE MOLDED FOR A GOLF BALL ENVELOPE, AND GOLF ENVELOPE AND BALL OBTAINED. THE ENVELOPE INCLUDES A MIXTURE OF A THERMOPLASTIC URETHANE WITH A SHORE A HARDNESS LESS THAN 95, AND AN IONOMER WITH A SHORE D HARDNESS GREATER THAN 55. THE RELATIVE QUANTITIES OF URETHANE AND IONOMER ARE SET. SO THAT THE ENVELOPE OBTAINED SHOWS A HARDNESS SHORE C INCLUDED BETWEEN 70 AND 85. APPLICATION: OBTAINING A GOLF BALL WITH GOOD USAGE CHARACTERISTICS WITH A SHORT IRON AND A WOODEN ROD (CLUB), AS WELL AS ' GOOD RUNNING ABILITY IN DIRECTION OF HOLES.

Description

The present invention relates to golf balls and more

  particularly, an improved golf ball envelope, which can be used to make balls, including two-piece balls, having superior characteristics of use with a short iron and other characteristic modes of use

in the game.

  Balatum and balatum blends with elastomeric or plastic materials have been the material of choice for many years to produce high quality golf ball envelopes. These materials have good properties

  molding and, therefore, they can be easily molded by

  pressure around a spherical core, having a winding of wire, to produce a high quality golf ball. An experienced player can rotate a ball with a coil of wire and a balatum envelope, so that the

  ball will be amortized or fly away or have the counter-rotation required

  to stop abruptly on the ground ("green").

  These properties for use in the game are extremely important in a game with short irons and they can not be exploited

  clearly than by relatively experienced players.

  Balatum and its synthetic substitutes

  trans-polybutadiene and trans-polyisoproene are essential.

  today replaced by new materials. With the exception of a few sets of golf balls sold by specialty stores to professional golfers and those who would like to look like or emulate them, newer synthetic polymers are the material of choice for bullet wraps. Among the new synthetic materials, those which are by far the most commonly used are constituted by a set of ionomers which E.I. Dupont de Nemours & Company sells under

  the trademark "SURLYN". These materials include copoly-

  olefins, typically ethylene, with a carboxylic acid

  The ethylenically unsaturated group has a, A, such as methacrylic acid.

  Metal ions, such as sodium or zinc, are used to neutralize some of the acid groups in the copolymer, giving

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  a thermoplastic elastomer which has several advantages, especially a cost advantage, compared to balatum. The properties of the ionomers which are manufactured by modifying the identity of the comonomers, the fraction of the polymer comprising the carboxylic acid, the molecular weight of the polymer, the degree of neutralization of this polymer, and the identity of the metal ions that are used. Adjustment of these parameters gives resins of ionomers having different values of the index

  melt flow, hardness, flexibility or

  lience and other mechanical properties which, in an envelope of

  golf ball, affect the resistance to incisions, the resistance

  tear, general durability and resilience or flexibility. U.S. Patent No. 3,819,768 (RP Molitor) discloses that mixtures of sodium neutralized ionomer resins with, as a class, zinc neutralized ionomer resins, have certain advantages that the you could not get in any other way. Among these advantages is the production of an unexpectedly high coefficient of restitution or rebound of

  golf balls having the envelope formed of a mixture of ionomers.

  Such wrappings also resist cold cracking, they have excellent aging properties and are unexpectedly durable. The development of an envelope with a mixture of "Surlyn" was the major factor in the production of two-part balls with envelopes which, for all cases in practice, can not be incised during the game, and which, when struck, goes further than any other ball meeting the USGA (United States Golfers Association) regulation, as measured in controlled trials, when these battles are hit by golfers or

by testing machines.

  While the balls with a winding of a wire and covered with a balatum envelope are easily cut

  and are very expensive, they nevertheless have excellent characteristics

  in a game where they are hit with short irons. It is much more difficult to give a rotation to a

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  battlle in two parts, covered with an ionomer envelope.

  Frequently, experienced players note that the two-part, ionomer-coated bullets have a

unsatisfactory "reaction"

  The patent literature is full of proposed formulations for envelopes and seeking improvements through

  compared to the balatum and ionomer envelopes that have been

  successful in the trade. Polyurethanes, thermoplastic rubbers, various block copolymers, polyesters and polyamides have been proposed, as well as various mixtures comprising such materials. Examples that may be mentioned include US Pat. No. 3,359,231, US Pat. No. 4,398,000, US Pat. No. 4,234,184 and US Pat. No. 4,295,652.

  US-A-4,248,432, US-A-3,989,568, US-A-3,310,102, US-A-4,337,947,

US-A-4,123,061 and US-A-3,490,146.

  The manufacture of balls in two parts, that is to say

  bales comprising a flexible, molded, solid and solid core and an envelope, has many important advantages

  compared to more expensive bales having a coil of wire.

  We therefore need two-piece balls with characteristics

  use, during a game with short irons,

  bales with a coil of wire and a

balatum envelope.

  It has just been discovered that a key to

  tion of a ball in two parts having properties, when used in the game, similar to those of balls comprising a winding of a wire with a balatum envelope, consists in providing, around a flexible molded inner core, an envelope having a Shore C hardness of less than 85. The envelope of the new golf ball of the invention is in a composition comprising a mixture

  of 1) a thermoplastic urethane having a Shore A hardness of less than

  less than 95, and 2) an ionomer having a Shore D hardness greater than 55. The ionomer comprises olefinic groups having 2 to 4 carbon atoms, copolymerized with acrylic or methacrylic acid groups and crosslinked by metal ions, preferably sodium or zinc ions. The main components of the envelope constituted by a mixture are present in a weighted ratio

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  for providing an envelope material having, after molding, a Shore C hardness of between 70 and 85. Preferably, the urethane forming part of the shell material has a tensile strength greater than 17250 N / mrrm2 (2500 pounds per square inch) and elongation at break greater than 250%. A preferred material for making the shell comprises about 8 parts of the thermoplastic urethane and 1 and 4 parts of the ionomer. Preferably, the envelope is not more than 1.524 mm (0.060 inches thick). Thinner envelopes seem to maximize features

  possibility of using bullets in a game with short iron.

  The shell composition of the invention may be used in connection with the manufacture of bales having a coiled wire, but the composition is preferably used to manufacture bales having molded cores. Bales in two parts, made with the envelope of the invention, have properties of use in a game with short fert as good or better than battlles with winding a fit and envelope

  in balatum, but they are much more durable. They also -

  properties, when used in a game with wooden canes or "clubs", better than conventional two-part balls, and they allow experienced golf players to apply one. rotation to dampen or to apply a volley ("shot"). The ability to roll The ball to a hole is

also improved.

  Tests have shown that the rotation impressed by a No. 9 iron to a two-part bale having the shell material of the invention is about 9,550 rpm instead of 400 rpm for a ball of the invention. state of the art, the two-part bales having ionomer resin shells. This compares favorably to bullets having a coiled wire and a balatum shell and which, under the same striking conditions, have a rotation speed of about 9,700 rpm. The term "two-part bale" as used herein refers primarily to bales consisting of a molded core and an envelope, but it also includes bales having a separate solid layer under the shell as described, for example , in US-A-4,431,193 (Nesbitt), and other bullets having cores without winding

of wire.

  It is believed that the greatest rotational speed that can be applied when bales having the envelope of the invention are appropriately struck is mainly due to the softness of the mixed material constituting the envelope. When struck, the envelope deforms significantly more than for balls with ionomer envelopes, and testing has shown that there is a larger contact area between the base and the face of the cane or "club" . This allows the best player to give the ball a cushion, a direct send or a counterweight as dictated by the situation, and allows the player to execute better shipments and other

  blows to the field ('green').

  For example, less than 45.5 m (50 yards), the two-part bales of the invention often outperform bales having a winding wire and a balatum envelope. With regard to the possibility of rolling to a hole, the two-piece balls comprising the envelope of the invention have a lower rebound than conventional two-piece balls, and they have a greater contact time with the ball. face of the cane intended to roll the bald. These features combine to allow the player

  to better control the line and the rolling distance to a hole.

  Preferred components of the shell material include a thermoplastic polyurethane consisting essentially of primary linear polymer chains. The structure of such chains preferably comprises long segments of flexible chains connected end to end, via covalent chemical bonds, with rigid chain segments. Flexible segments

  typically are polyester chains or low point polyethers.

  melting with diisocyanate bonding. The rigid segments

  take simple diurethan bridges and chain segments

  high melting urethanes formed by the reaction of the diiso-

  cyanate with small glycols. It is believed that the hydrogen bonding and other attractive forces between the rigid chain segments produce domains that exert mutual attractions, behave somewhat like cross-linking crosslinks,

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  and may exhibit reversible effects due to heat and

solvation.

  The second preferred compound of the shell composition is an ionomer comprising olefinic groups having 2 or 4 carbon atoms copolymerized with acrylic or methacrylic acid groups which are at least partially neutralized.

  by a sodium or zinc ion, for example an "SURLYN" ionomer. The inclu-

  The ionomer composition provides the casing with a much greater degree of cut resistance than the balatum and helps to adjust the melt flow index of the blend to facilitate molding. The shell composition of the invention can be used to formulate golf ball casings by injection or compression molding around cores comprising a coiled wire, solid or solid molded cores of known composition, high-coefficient molded cores such as those described in the patent application filed the same day Dar the Applicant, or cores having a hard core and a soft outer layer. Various combinations of technologies can also be used

solid or solid nuclei.

  Thus, it is an object of the present invention to provide: an envelope-injection moldable or compression molded composition around a solid molded core, to produce golf ball envelopes that are more durable and more resilient tears as bullets coated with a balatum rubber wrap; - a two-part ball having characteristics of use

  in a game using short irons and other features

  use ticks equal to or greater than bales with a winding wire and a balatum envelope; and an envelope composition compatible with paints based on

  urethane, which resists chipping and peeling.

  These objects and features of the invention

  from the following description, which is illustrative and

in no way limiting.

  The shell composition of the invention comprises

  in its broadest aspects, a mixture of a thermoset urethane

  plastic having a Shore A hardness of less than 95, with an ionomer resin having a Shore D hardness greater than 55, in sufficient weight ratios to provide a golf ball casing having a Shore C hardness of between 70 and 85, preferably

  between 75 and 80, and even better in the neighborhood of. 78.

  The thermoplastic urethanes useful in the shell preferably consist essentially of linear primary polymer chains having mostly relatively long segments of flexible chains connected end-to-end, via covalent chemical bonds, by rigid chain segments. of the

  flexible segments may be polyester or poly-polyester chains

  low melting point, diisocyanate bonded ethers. Rigid segments include simple diurethane bridges, which are obtained when a diisocyanate couples by coupling to polyester or polyether molecules. The rigid segments may comprise fairly long segments of high melting point diurethane chains, which are formed by the reaction of a diisocyanate with a low molecular weight glycol as a chain extender. The polar nature of the recurrent segments of rigid urethane chains creates their strong characteristics of mutual attraction, aggregation, orderly presentation into crystalline and polycrystalline domains in the mobile polymer matrix. It is believed that urethane hydrogen atoms and carbonyl and ether oxygen atoms allow for high hydrogen bonding between the polymer chains. This apparently limits the mobility of urethane chain segments in domains. These attractions and intermingling of chains produce thermo-labile pseudoreactions and give resins which may have the surface properties of solid rubbery vulcanizates. Preferred thermoplastic urethanes in the shell composition of the invention have a tensile strength of at least 17250 N / mm 2 (2500 psi) and an elongation at break of at least 250% . Even better, they have a tensile strength of

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  27600 N / mm2 (4000 psi) and elongation at break

400%.

  Such materials are commercially available under the trademark "TEXIN" at Mobay Chemical Company, under the trademark "ESTANE" at B.F. Goodrich, under the brand name

  "PELLETHANES" at Upjohn Company or under the trade mark

  "Q THANES" at K.J. Quinn Company. The "TEXTIN 480AR" material of Mobay Chemical Company is the presently preferred thermoplastic urethane for use in the composition of the invention. Can also

use "TEXTIN 591A".

  The other major component of the shell composition is an ionomer resin comprising a copolymer of an olefin

  having 1 to 4 carbon atoms with a monocarboxylic acid, typically

  only acrylic or methacrylic acid, at least partially neutralized by a metal ion. These materials are sold under the trademark "SURLYN" by EI Dupont de Nemours & Co. and, as noted above, they exist in very different qualities which differ in their average molecular weight, the percentage of carboxylic acid monomer, the degree neutralization, the identity of the neutralizing ion and other factors. Any of the "SURLYN" ionomers or other ionomers of the type described may be used having a Shore D hardness of at least 55. The presently preferred material is "SURLYN 1702". "SURLYN 1702" is a copolymer of ethylene and methacrylic acid, which is believed to comprise about 96.5% free acid and 1.2% zinc. Its average index

  melt flow rate is about 14.

  The presence of ionomers in the mixture serves to adjust the melt flow index to optimum values for injection or compression molding, and also provides resistance to tearing and cutting and durability.

  general envelopes made using the mixture of the invention.

  The urethane resin and ionomer resin components thus co-operate in use to provide a remarkable, if not unique, combination of durability, golf playability, and ease of manufacture. The nature of the wrapper material is such that good players can dampen, "point" or counter-rotate the base, although this has a two-part structure, the wrapper having greater strength incisions and in general, better durability than bullets with a winding wire and a balatum envelope. It is believed that the main reason for imparting a higher rotational speed to the base when

  it is struck that the material of the envelope becomes more easily deformed

  In fact, ferst, in particular short irons, tend to "bite" into the ball without conferring on it.

permanent deformation.

  The nature of the molded cores that can be used with the casing is not part of the present invention, although molded cores rather than cores having a wire coil are preferred because of their lower cost. returns and their best performance Thus, the envelopes of the invention can be used with cores of the type described in the

  US-A-4,264,075, US-A-4,169,599 or US-A-4,141,559.

  Solid or solid cores are typical

  compression molded from a compound billet

  unvulcanized or slightly vulcanized elastomer, comprising a poly-

  cis-rich butadiene and a metal salt of an acid

  ethylenically unsaturated carboxylic acid at a, c, as mono- or di-

  acrylate or zinc methacrylate. To obtain a high coefficient of recovery or rebound in the core, the manufacturer incorporates a small amount of a metal oxide such as zinc oxide. We can

  include amounts of metal oxide greater than those required

  to obtain the desired coefficient, in order to increase the weight

  the core, so that the finished ball gets closer-

  the USGA Association's highest weight limit of 46 g (1.620 oz). Other materials may be used in the core composition, including compatible rubbers or ionomers, and low molecular weight fatty acids such as stearic acid. Free radical initiator catalysts such as peroxides, in the composition for cores, so that, by application of heat and pressure, it occurs

  a complex reaction of vulcanization maturation or

lation.

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  There is further described a golf ball core which is vulcanized with a peroxide and a polyfunctional isocyanate having 3 to 30 carbon atoms. Bullets with

  nuclei made with the help of a small amount of such an iso-

  cyanate, preferably a diisocyanate, for example 1.0% 4,4'-diphenylmethane diisocyanate, have a higher and improved recovery or rebound coefficient. The coefficient of restitution or rebound is defined as the ratio between the speed of return and the speed of arrival of the test ball or a battlle thrown against a hard plate at a chosen initial speed, for example 38.1 m / s (125 feet per second). The composition may, moreover, be identical to prior compositions of polybutadiene rings /

  metal acrylate. These nuclei can be used with the compounds

  envelope constructions of the invention to produce a battlle with

  high and high initial velocity, closely approximating the limit set by the USGA association, and which nonetheless has excellent behavioral properties in a game in which we use

a short iron.

  An envelope having a hard inner core and a softer outer layer is described. The core may be made by formulating a conventional core composition of the type described above by extruding billets of appropriate size, applying to the surface layers of the billet a material which modifies the crosslinking, for example sulfur or materials. with sulfur, and compression molding. The inner parts of the core vulcanize normally to give a resilient and hard center. An outer layer of the core, having a thickness of at least about 5.8 mm (about 0.20 inches), vulcanizes differently due to the presence of sulfur or sulfur bearing material and provides a region of

  outer soft, having for example a Shore A hardness of about 25.

  This type of core can also be used with the envelope of this

  invention for producing bullets with excellent characteristics -

  behavior when used with short irons.

  The invention will be better understood by using

  following non-limiting examples.

  An envelope composition is prepared according to

  the present invention, by mixing 80 parts of thermoset urethane

  plastic "TEXIN 48OAR" (Mobay), 20 parts of "SURLYN 1702" (Dupont)

  and 0.4 parts of TiO2. After thorough mixing, the material for

  loppe has a melt flow index of 0.89. The composition is molded by injection around conventional nuclei

  of the type described above, at 2320C (450 F) to produce enzymes

  1.524 mm (0.060 inch thick) lopps. Balls are painted and their properties checked against a golf ball of similar structure, except that the shell material is a mixture of a sodium ionomer with a zinc ionomer, and with respect to a ball having a yarn winding and a balatum envelope. Struck by an iron No. 9, bullets having the envelope of the invention have a rotation speed of 9550 rpm, while ionomeric envelope bullets have a rotation speed of 5400 rpm and bullets. balatum envelope a rotation speed of 9700 rpm. When they are "cut" by an iron No. 3, the balls of the invention are very slightly damaged, the ionomer-shelled bullets do not bear marks and the ball is wrapped

  Balatum is cut up to the threads. In actual tests

  killed by professional golf players, the bullets of the invention

  were considered equal or superior to balatum-shell bullets for their ability to be used in a game.

implementing short irons.

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Claims (18)

R E V E N D I C A T I ONS   A composition for molding a golf ball casing, characterized in that it comprises a thermoplastic urethane having a Shore A hardness of less than 95 and an ionomer comprising olefinic groups having 2 to 4 carbon atoms, copolymerized with a monocarboxylic acid having 3 or   4 carbon atoms, said acid groups being at least partially   The ionomer having a Shore D hardness greater than 55, and the relative amounts of urethane and ionomer being sufficient to produce an envelope having   a Shore C hardness of between 70 and 85.   2. Composition according to claim 1, characterized in that the ionomer is neutralized with a metal selected from among the sodium and zinc.   3. Composition according to claim 1, characterized in that it comprises 8 parts of urethane and 1 to 4 parts of the ionomer. 4. = Composition according to claim 1, characterized in   it further comprises titanium dioxide.   5. Composition according to claim 1, characterized in that the urethane has a tensile strength of at least   17250 N / mm and elongation at break greater than 250%.   A golf ball having a core and a casing, characterized in that the casing comprises a metange of thermoplastic urethane polymers having a Shore A hardness of less than and an ionomer having a Shore D hardness greater than 55, ionomer comprising olefinic groups having 2 to 4 carbon atoms   copolymerized with acrylic or methacrylic acid groups   These groups are at least partially neutralized by a metal ion and the relative amounts of urethane and ionomer are sufficient to produce an envelope having a Shore C hardness. between 70 and 85. 2 5 7 4 4 1 9   Golf ball according to claim 6, characterized   in that the core is a solid, elastic, molded sphere.   8. golf ball according to claim 6, characterized in that the ionomer is neutralized with a metal selected from sodium and zinc. Golf ball according to claim 6, characterized in that its envelope comprises 8 parts of the urethane polymer and 1 to 4 parts of the ionomer.   Golf ball according to claim 9, characterized   in that its envelope comprises about 2 parts of the ionomer.   Golf ball according to claim 6, characterized   in that the casing has a thickness of no greater than 1.524 mm.   12. Golf ball according to claim 6, characterized in that it also comprises a coating formed of a paint polyurethane type.   13. Golf ball according to claim 6, characterized in that, when struck by an iron n-9, it presents a   rotation speed above 9000 rpm.   14. golf ball cover, characterized in that it comprises a mixture of a thermoplastic urethane having a Shore A hardness of less than 95 and an ionomer comprising olefinic groups having 2 to 4 carbon atoms, copolymerized with a monocarboxylic acid having 3 or 4 carbon atoms, these groups being at least partially neutralized by a metal ion, the ionomer having a Shore D hardness greater than 55, the relative amounts of urethane and ionomer being sufficient to produce an envelope with a Shore C hardness between 70 and 85.   15. Envelope according to claim 14, characterized in that the ionomer is neutralized by a metal chosen by the sodium and zinc.   16. Envelope according to claim 14, characterized in that it comprises 8 parts of the urethane and 1 to 4 parts of the ionomer. 17. Envelope according to claim 14, characterized   in that it also comprises titanium dioxide.   18. Envelope according to claim 14, characterized in that the urethane has a tensile strength of   less 17250 N / mm. and an elongation at break greater than 250%.