JPS61149178A - Golf ball having improved game characteristics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a golf ball, and particularly to golf balls that improve playability with short irons and other golf balls.
A golf ball with excellent properties, especially a two-piece golf ball (t
The present invention relates to an improved golf ball cover useful in the manufacture of WO-PIECE) DE-YV.

Balata and mixtures of balata with elastic or plastic materials have been of choice for many years in the manufacture of top-quality ball covers. These materials have good moldability and can be easily compression molded around a spherical wound center to produce high quality golf balls. Experienced players can apply spin to a balata-covered wound ball so that the ball has a fade or draw while in flight, or backspin to stop immediately on the green. . These game characteristics are particularly important in short iron play and can only be fully exploited by relatively skilled players.

Balata and its synthetic substitutes transpolybutadiene and transpolyisoprene have now been largely replaced by new materials. New synthetic polymers are being used as cover materials in all but a few types of golf balls supplied to professional golfers and comparable players through pro shops.

The most commonly used new synthetic materials are:
DuPont de Nemo (g, 1. DuPont de Nemo
It is a type of ionomer sold under the trade name 5URLYN by Urs & Company. Materials of this type consist of copolymers of olefins, typically ethylene, and alpha, beta-ethylenically unsaturated carbo/acids such as methacrylic acid. Metal ions, such as sodium or zinc, are used to neutralize some of the acid groups in the copolymer, resulting in a thermoplastic elastomer that has several advantages, including being less expensive than balata. Many types of ionomers can be made by varying the type of comonomer, the proportion of the carboxylic acid polymer, the molecular weight of the polymer, the degree of neutralization of the polymer, and the type of metal ion used. These 7? By adjusting the lameter, the ionomer resin can be made to have different melting index (m).
elt 1ndex ), hardness, elasticity, and mechanical properties that further influence cut resistance, shear resistance, overall durability, and elasticity in the golf ball.

U.S. Pat. No. 3,819,7 to R.P. Molitor
According to No. 68, a class consisting of a mixture of sodium-neutralized and zinc-neutralized ionomer resins has advantages not available with other methods. Another advantage in producing golf balls with mixed ionomer covers is the ability to obtain very high coefficients of restitution.

Such covers also do not crack at low temperatures, have good aging properties and are more durable. It has a cover that does not actually run out during the competition, and it has a cover that does not actually run out during the competition, and it also has a cover that does not actually run out during the competition.
The development of the SURLYN blend cover was one of the most important elements in producing a two-piece ball that flies farther than an SGA standard ball.

Balata-covered thread-wound balls break easily and are very expensive, but they have excellent competitive characteristics for short irons. It is very difficult to reduce spin on a two-piece ball with an ionomer cover.

Experienced players often feel the hitting feel (fee'l) for two-piece balls with ionomer covers.
says he is not satisfied.

There are a number of patents that provide cover compositions that are improvements to the commercially successful grasshopper and ionomer covers.

Polyurethanes, thermoplastic rubbers, various block copolymers, polyesters and polyamides, as well as various mixtures of these materials are provided. For example, there are the following US patent specifications: 6. Ro59.231.4,3
98,00 (14.234,184.4,295,65
2.4,248,432, 9 89,5 6 8,
3,3 1 0,1 0 2,4,337,947.4
．． 123,061 and 3,490,146° The production of two-piece balls, i.e. balls consisting of a solid molded resilient center and cover, has a number of important advantages over the more expensive wound balls. . Therefore, there is a need for a two-piece ball that has competitive characteristics in short irons comparable to a wound balata covered ball.

The key to producing a two-piece ball with similar playing characteristics to a wound balata covered ball is to have a cover with a Shore C hardness of less than 85 around an inner resilient molded center. I understand. The novel golf ball cover of the present invention has (1) a Shore A hardness of 9;
A thermoplastic urethane having a Shore D hardness of less than 55; and (2) an ionomer having a Shore D hardness greater than 55.

Ionomers consist of olefin groups with 2 to 4 carbon atoms copolymerized with acrylic or methacrylic acid groups and crosslinked with metal ions, preferably sodium or zinc ions. The main components of the mixed cover are used in weight ratios that will yield a cover material with a Shore C hardness of 70-85 after molding.

Preferably, the urethane component of the cover material has a tensile strength greater than 2500 psi and an elongation at break greater than 250 modulus. A preferred cover material consists of about 8 parts thermoplastic urethane and 1 to 4 parts ionomer. Preferably, the thickness is less than 0.060 inch. It seems that the thinner the cover, the greater the competitive characteristics of the ball with short irons.

Although the cover compositions of the present invention may be used in the production of wound balls, they may also be used in the production of balls with shaped centers [5].
is preferable. Two-piece balls made using the covers of the present invention have the same or better playing characteristics in short irons than balata-covered wound balls, and importantly, have better durability.

It also has better playing characteristics with the wood than conventional balls, allowing experienced golfers to apply spin to fade or draw shots. It also makes putting easier.

Test results showed that a two-piece ball made of the cover material of the present invention had a rotational speed of about 995 Orpm when hit with a 9 iron, while a two-piece ball with an ionomer cover had a rotational speed of about 5400 rpm. This test favors a wound ball with a balata cover, resulting in a rotational speed of about 973 Orpm when hit under the same conditions. Two-piece balls, as used herein, primarily refer to balls consisting of a molded center and a cover, but also balls with another solid layer beneath the cover, such as Ne5B.
It also includes the balls disclosed in U.S. Pat. No. 4,413,193 to IT and other non-wound center balls.

It is believed that the reason why a ball having the cover of the present invention can be hit with good spin when hit appropriately is mainly due to the softness of the mixed cover. During impact, the cover deforms much more than an ionomer covered ball, and testing has shown that there is a greater contact area between the ball and the club face.

This allows a good player to fade, draw or backspin the ball at will, and to better chip shots or other shots toward the green.

On short distance shots, such as less than 50 yards, the two-piece dart of the present invention often performs better than a balata-covered wound ball. Regarding ease of putting, the two-piece pole including the cover of the present invention has less drop rebound and longer contact time on the face of the putter than a conventional two-piece pole.

Together, these features allow players to better control the line and distance of their putts.

A preferred component of the cover material is a thermoplastic polyurethane consisting essentially of linear primary polymer chains. A preferred structure for such chains is one in which long, freely bending chain segments are joined end-to-end with a rigid chain segment through covalent chemical bonds.

The free-flexing section is typically a diisocyanate coupled low melting point polyester or polyether. The hard section contains a single diurethane bridge and a high melting point urethane chain section resulting from the reaction of a diisocyanate with a low molecular weight glycol. Hydrogen bonds and other bonding forces between rigid chain segments create regions that tighten together, act like cross-links, and can be undone by heating and solvation.

A preferred second component of the cover composition comprises olefinic groups having from 2 to 4 carbon atoms copolymerized with acrylic or methacrylic acid groups, the acid groups being at least partially sodium or zinc. Ionomers that are neutralized by ions, such as the 5URLYN ionomer. The inclusion of the ionomer provides the cover with much better cut resistance than balata, and also makes the melt index of the mixture more controllable and easier to mold.

The cover compositions of the present invention may include a wound center, a solid molded center of known compositions, a molded center with a high coefficient of restitution, such as U.S. Pat.
The invention can be used to make golf golf ball covers by injection or compression molding around the center of a mold as described in the '088 patent or a mold having an inner hard midsection and an outer soft layer.

For solid cores, a combination of techniques may be used.

It is therefore an object of the present invention to produce a golf ball cover that can be injection molded or compression molded around a solid molded center to produce a golf ball cover that is more durable and cut resistant than a balata rubber cover. An object of the present invention is to provide a cover composition that can be used.

Another object is to provide a two-piece pole that has the same or better playing characteristics with short irons and others than wound balata covered balls. Another object is to provide a cover composition that is comparable to urethane-based paints and is less likely to chip or peel.

These objects and features of the present invention will be explained in more detail below.

The broadest range of cover compositions of the present invention include thermoplastic urethanes having a Shore A hardness of less than 95 and a Shore D hardness of 5.
Ionomer resin with a Shore C hardness of 70
to 85, preferably 75 to 80, and most preferably about 78.

Preferably, the thermoplastic urethane used in the cover consists essentially of linear primary polymer chains containing many specific long freely bendable chains joined end-to-end by rigid chain segments through covalent chemical bonds. The freely bending segments are diisocyanate coupled low melting point polyester or polyether chains. The hard section contains a single diurethane bridge that occurs when a diisocyanate couples to a polyester or polyether molecule. The hard sections consist of long, high melting point urethane chain sections resulting from the reaction of the diisocyanate with the extending component, low molecular weight glycol.

- Repeated polarity of rigid urethane chain segments results in strong interconnections, aggregation and arrangement into crystalline or polycrystalline domains in a fluid polymeric matrix. It is believed that the hydrogen atoms of the urethane and the carbonyl and ether oxygen partners create extensive hydrogen bonding in the polymer chain. This clearly limits the movement of the urethane chains within the region. These bonds and chain entanglements create thermally sensitive pseudo-crosslinks, and
A resin is produced that exhibits the surface properties of vulcanized rubber products with strong elasticity. Preferred thermoplastic urethanes in the cover compositions of this invention have a tensile strength of at least 2500 lb/in@2 and an elongation at break of at least 250%. Most preferably, the tension is 4000 lb/in 2 and the extrusion at failure is 400 inches.

Such materials are manufactured by Mobay Chemical C
From the company, the product name of TEX Engineering is B, F',
From Goodrich under the product name ESTANE, tJp
PELLFJTHANK from john Company
With the product name of S, also J, Q, uinn Comp
It is commercially available under the trade names of -any to Q and THANK8.

Mobay Chemical Company TF
iX1N480AR is currently the preferred thermoplastic urethane for use in the compositions of the present invention. TFiX Engineering N59
1A may be used.

The other main component of the cover composition is an ionomeric resin consisting of a copolymer of a monocarboxylic acid, typically acrylic acid or methacrylic acid, and an olefin of 2 to 4 carbon atoms, at least partially neutralized with metal ions. It is. These materials are E, Engineering.

Dupont de Nemours Co, to 5I
It is commercially available under the trade name JRLYN, and as mentioned above, there are many types that differ in average molecular weight, proportion of carboxylic acid monomer, degree of neutralization, type of neutralizing metal, and other factors. Any 5 if the Shore D hardness is at least 55
URLYN or other ionomers of the type described above may also be used. The currently preferred material is 5URLYN1702. 5URLYN 1702 is about 96.5% free acid
and a copolymer of methacrylic acid and ethylene believed to consist of 1.2% zinc.

Its average melting index is approximately 14.

The presence of the ionomer in the mixture provides a melt flow index that is optimal for injection or compression molding, and provides covers used in the mixture with cut resistance and general durability.

The use of urethane and ionomer resin components thus work together to provide a unique combination of durability, playability and ease of manufacture. The nature of the cover material of the present invention allows skilled players to apply fades, draws or punk spins even on two-piece balls. Moreover, the cover of the present invention has better cut resistance and general durability than the wound ball of the balata cover. It is believed that the main reason why the ball is able to spin better when hit is because the cover material of the present invention deforms more easily than the ionomer cover. Irons, particularly short irons, therefore tend to "bite" the ball without permanently deforming it.

Although the nature of the molded center used with the cover is not a requirement of the invention, molded centers are preferred over wound centers because of their lower cost and superior performance. Accordingly, the cover of the present invention is disclosed in U.S. Patent No. 4,264,0.
75.4,169,599 or 4,141,559.

The normal solid core typically consists of a polybutadiene with a high cis content and a metal salt of an α,β-ethylenically unsaturated carboxylic acid, such as a zinc salt of mono- or diacrylic acid or methacrylic acid, which is not hardened. or compression molded from a slap of an easily cured elastomer composition.

To increase the core's coefficient of restitution, manufacturers include small amounts of metal oxides, such as zinc oxide. Including more metal oxide than is necessary to increase the coefficient of restitution will result in a ball that is heavier in the center and can approach the USGA weight limit of 1.620 ounces. can. Other materials may be included in the core composition, including compatible rubbers or ionomers and small fatty acids such as stearic acid. Free-radical initiator type catalysts, such as peroxides, are included in the core composition to initiate complex curing or crosslinking reactions when heat or pressure is applied.

US Patent Application No. 680,088 discloses golf balls cured with peroxides and polyfunctional incyanates of 3 to 30 carbon atoms. Small amounts of incyanates, preferably diisocyanates such as 4,4'-
M-Rule with a core made with 1.0% diphenylmethane diinocyanate exhibits a good high coefficient of restitution. The coefficient of restitution is determined by moving the center or ball to be tested towards a hard plate at a constant initial velocity, e.g. 125 ft, /
sec is defined as the ratio of the outgoing speed to the incoming speed when thrown out. This core composition includes a known polybutadiene metal acrylate core composition;
In other respects they are the same. This core, together with the cover composition of the present invention, can be used to produce a ball that has a high coefficient of restitution ([an initial velocity close to the TSGA limit) and exhibits excellent playing characteristics in short irons.

US patent application Ser. This center is prepared by preparing a normal center composition of the type described above,
A suitably sized slap is extruded, a crosslinking altering material such as sulfur or sulfur-containing material is applied to the surface layer of the slap, and compression molded. The inner part within the core is hardened in the usual manner for producing hard elastic cores. The outer layer of the center, which is at least about 0.20 inches thick, is otherwise cured. This is because sulfur or sulfur-containing materials are present to produce a soft outer layer, such as one with a Shore A hardness of about 35. The core of this mold and the cover of the present invention can be used together to produce a ball with excellent short iron playing characteristics.

Examples are shown below, but these are not intended to limit the scope of the invention.

TEXIN 480 A R thermoplastic urethane (M
obay) 80 copies, 5URLYN 1702 (Du
pOnt Inc.) and 14 parts of T102 were mixed. After mixing well, the melt flow index of the cover stock was 0.
．． It was 89. Approximately 45 mm on the normal center of the mold described above.
A 0.060 inch thick cover was produced by injection molding at 0'F. After painting the ball and testing its properties, we compared it to a golf ball of the same construction, except for the use of a cover material made of a mixture of sodium and zinc ionomers, and compared it to a wound ball with a balata cover.

The rotational speed of the ball with the cover of the invention hit with a 9 iron was 9550 rpm, while the rotational speed of the ball with the ionomer cover was ij 5400 rpm.

The rotation speed of the ball of the balata cover was 9700 rpm. When hit with the blade of a 3-iron, the ball of the present invention is only slightly scratched, and the ionomer cover? - The ball was undamaged, but the ball of the balata cover was cut and the damage extended to the thread winding. In testing by professional golfers, the short iron playing characteristics of the ball of the present invention were found to be equal to or superior to balata covered balls.

The present invention can be modified in various ways other than those described above without departing from its spirit and scope.

Claims (18)

[Claims] (1) Comprising a thermoplastic urethane having a Shore A hardness of less than 95 and an olefinic group having 2 to 4 carbon atoms copolymerized with a monocarboxylic acid having 3 to 4 carbon atoms; The acid groups are at least partially neutralized with metal ions and the ionomer has a Shore D hardness of greater than 55 in a sufficient proportion to produce a golf ball cover having a Shore C hardness in the range of 70 to 85. A material composition for forming a golf ball cover, comprising: (2) Item (1) above, wherein the ionomer is neutralized with a metal selected from the group consisting of sodium and zinc.
The composition described in . (3) The composition according to the above item (1), comprising 8 parts of the urethane and 1 to 4 parts of the ionomer. (4) The composition according to item (1), further comprising titanium dioxide. (5) the urethane has a tension of at least 2500 lbs.
/in^2 and has an elongation rate at break of greater than 250%. (6) A thermoplastic urethane polymer having a Shore A hardness of less than 95, and an olefinic group having 2 to 4 carbon atoms copolymerized with an acrylic or methacrylic acid group, the acid groups being at least partially A cover comprising a mixture containing an ionomer that is neutralized with metal ions and has a Shore D hardness greater than 55 in a sufficient proportion to produce a golf ball cover having a Shore C hardness in the range of 70 to 85. A golf ball with a central part and a central part. (7) The golf ball according to item (6), wherein the center portion is a molded elastic solid sphere. (8) Item (6) above, wherein the ionomer is neutralized with a metal selected from the group consisting of sodium and zinc.
The golf ball described in . (9) The golf ball according to item (6), comprising 8 parts of the urethane and 1 to 4 parts of the ionomer. (10) The golf ball according to item (9), which contains about 2 parts of the ionomer. (11) The golf ball according to item (6), wherein the cover has a thickness of 0.060 inch or less. (12) The golf ball according to item (6), further comprising a coating of polyurethane paint. (13) The golf ball according to item (6) above, which has a rotational speed greater than 9000 rpm when hit with a No. 9 iron. (14) Thermoplastic urethane having a Shore A hardness of less than 95;
and an olefinic group having 2 to 4 carbon atoms copolymerized with a monocarboxylic acid having 3 to 4 carbon atoms, the acid groups of which are at least partially neutralized with metal ions; A golf ball cover comprising a mixture comprising an ionomer having a Shore D hardness greater than 55 in a sufficient proportion to produce a golf ball cover having a Shore C hardness in the range of 70 to 85. (15) The ionomer is neutralized with a metal selected from the group consisting of sodium and zinc (1).
The cover described in 4). (16) 8 parts of the urethane and the ionomers 1 to 4
The cover according to the preceding paragraph (14), consisting of (17) The preceding item (14) further comprising titanium dioxide.
). (18) The urethane has a tension of at least 2500 l.
The cover according to the preceding item (14), which has an elongation rate of b/in^2 and an elongation rate at breakage of greater than 250%.