GB2311293A - Golf ball with cover formed from hard and very low modulus ionomer resins - Google Patents

Description

X 2311293 1 -

DESCRIPTION

GOLF BALL WITH COVER FORMED FROM HARD AND VERY LOW MODULUS IONOMER RESINS Backcround This invention relates to golf balls, and, more particularly, to a golf ball having a cover which is formed from a blend of hard and soft ionomer resins. More particularly, the cover is formed from a blend of hard ionomer resin a very low modulus ionomer resin which is neutralized with magnesium ions.

Golf balls which are currently available fall into two general categories -- balls which include a balata cover and balls which include a more durable, cut-resistant cover. Balata covers are made from natural balata, synthetic balata, or a blend of natural and synthetic balata. Natural rubber or other dlastomers may also be included. Synthetic balata is trans polyisoprene and is commonly sold under the designation TP-301 available from Kuraray Isoprene Company Ltd.

Most cut-resistant covers utilize Surlyn ionomers, which are ionic copolymers available from E.I. du Pont de Nemours & Co. Surlyn ionomers are copolymers of olefin, typically ethylene, and an alpha-beta ethylenically unsaturated carboxylic acid, such as methacrylic acid. Neutralization of a number of the acid groups is effected with metal ions, such as sodium, zinc, lithium, and magnesium. DuPont's U.S. Patent No. 3,264,272 describes procedures for manufacturing ionic copolymers. Ionic copolymers manufactured in accordance with U.S. Patent No.

- 2 3,264,272 may have a flexural modulus of from about 14,000 to about 100,000 psi as measured in accordance with ASTM method D-790. DuPont's U. S. Patent No. 4,690,981 describes ionic copolymers which include a softening comonomer. Ionic copolymers produced in accordance with U.S. Patent No. 4,690,981 are considered "soft" ionic copolymers and have a flexural modulus of about 2800 to about 8500 psi. The disclosures of Patent Nos. 3,264,272 and 4,690,981 are incorporated herein by reference.

other cut-resistant materials which can be used in golf ball covers are ionic copolymers or ionomers available from Exxon under the name Iotek, which are similar to Surlyn ionomers except that acrylic acid is used rather than methacrylic acid.

Balata has been used as a cover for golf balls due to the excellent spin/playability properties and flight performance properties. However, Balata is an expensive material, and processing Balata golf balls is both time consuming and expensive.

Recently, ionomeric blends containing V.L.M.I (Very Low Modulus Ionomers) have been used for golf ball covers. The addition of V.L.M.I. improves playability properties, but sacrifices coefficient of restitution as a function of initial velocity (C.O.R./Initial velocity) and distance properties. Blends of lonomers containing V.L.M.I. are illustrated in U.S. Patent Nos. 4,884,814, 5,120,791, and 5,415,937.

- 3 Summary of the Invention

Recently, new V.L.M.I materials have been developed, neutralized using Mg (Magnesium) ions. The invention utilizes a blend of hard ionomers with Mg (Magnesium) V.L.M.I. (Very Low Modulus lonomers) co-polymers, which will allow improved C.O.R./I.V. properties compared to prior art, without any sacrifice in playability properties.

Hard lonomer shall be defined as follows:

75-85 by weight of an olefin (e.g., ethylene), 15-25% by weight of an a, P ethylenically unsaturated carboxylic acid (e.g., acrylic or methacrylic acid), having 10-90 of the carboxylic acid groups neutralized with a metal ion selected from the following: K,M9, Li, Zn, or Na., The hard ionomer.shall have a flexural modulus of 40,000-100,000 psi, a shore 'D' hardness of or greater, and a melt index of 0.5-5.0 g/10 min.

Mg (Magnesium) Very Low Modulus Ionomer shall be defined as follows:

65-79% by weight of an olefin (e.g., ethylene), 6-12% by weight of an a, P ethylenically unsaturated carboxylic acid (e.g., methacrylic), and 15- 25% by weight of an unsaturated salt of an acrylate ester, where 10-90% of the acid groups are neutralized with Magnesium ions. The Mg (Magnesium) V.L.M.I. shall have a flexural modulus of 3,000-10,000 psi, a shore 'D' hardness of 30-55, and a melt index of 0.5-5.0 g/10 min.

The Cover Blend of,the invention shall consist of:

1. 40-90% by weight of a Hard Ionomer (as defined 4 above), neutralized by metal ions (Li, Na, Mg, Zn, etc.), having a melt index of 0.5-5.0 g/10 min., a shore 'D' hardness of 65 or greater, and a flexural modulus of 40,000-100,000 psi, and 2. 10-60% by weight of a Magnesium V.L.M.I. (Very Low Modulus Ionomer) (as defined above), having a melt index of 0.5-5.0 g/10 min., a shore 'D' hardness of 30-55 or greater, and a flexural modulus of 3,000-10,000 psi.

The invention will now be further described by way of example, with reference to the accompanying drawings in which:- Figure 1 is a cross section of a golf ball which is formed in accordance with the invention; Figure 2 illustrates improved C.O.R. properties (at 150 ft/s) yielded by the invention, compared to prior art control blends;

Figure 3 illustrates improved C.O.R. properties (at 175 ft/s) yielded by the invention, compared to prior art control blends; and

Figure 4 illustrates comparable playability properties (as measured by PGA compression) of blends of the invention, as compared to prior art blends.

Description of Specific Embodiments

Figure 1 illustrates a two piece golf ball 10 which 1 includes a core 11 and a cover 12. The cover is formed primarily from a blend of ionomer resins as will be explained hereinafter. The cover may also include other conventional ingredients such as zinc oxidef titanium dioxide, blue toner, and optical brightener. The thickness of the cover is conventional and within the range of about 0.065 to 0.075 inch. The diameter of the core is about 1.535 to 1.545 inch and the outside diameter of the ball is about 1.680 inch. Other cover thicknesses and core sizes can be used.

Table 1 identifies the ionomer cover materials which are described herein.

Table 2 lists the properties of various cover compositions.

TABLE 1 COMPOSITION Indivi4u&l Materials Hard Ionomers % Type Melt Plexural Shore Material Ethylene Acid Neutraliz. Other Ion Index Modulus Do Surlyn 7930 85 15 47 Li 1.8 67,000 68 Surlyn AD 8181 80 20 50:- Li 1.1 97,000 73 Surlyn AD 8172 85 15 50 Mg 1.0 44,000 61 Surlyn 8940 85 15 29 Na 2.8 51,000 65 Surlyn 8220 80 20 50 Na 1.0 79,000 75 Surlyn 9910 85 is 58 Zn 0.7 48,000 64 Surlyn 9120 81 19 so Zn 1.0 42,000 73 V.L.M.I (Very Low Modulus Ionomers) % k. % % Type Halt Plexural Shore material Ethylene &c14 Noutralis, other Ion In4OX Nodulua DO Surlyn 9320 67-70 10 70 20-23 n-Ba Zn 0.6 3,700 42 Surlyn SEP 688-A 67-70 10 20-23 n-Ba Mg 7,100 51 n-Ba n-Butyl Aerylate Na - Sodium Li - Lithium Zn - Zinc Mg-Magnesium Melt Index - ASTM D-1238 Flexural Modulus - ASTM D-790 TABLE 2 - PHYSICAL PROPERTIES Cover Compositions (% by PGA Bhore C.O.R. C.O.R. C.O.R.

No.,. weight of ionower resin) Bize Comp Weight 150 fpo 175 fDa 200 fP 1 AD 8181 @ 100% 1.6883 113.9 45.44 71 0.794 0.769 0.738 2 8940 @ 100% 1.6873 109.7 45.37 68 0.785 0.757 0.728 3 AD 8181/SEP 688A @90/10 1.6579 111.3 45.41 70 0.788 0.762 0.734 4 8940/9320 @ 90/10 1.6874 108.7 45.33 68 0.779 0.754 0.724 AD 8181/SEP 688A @75/25 1.6872 106.8 45.33 66 0.780 0.755 0.726 6 8940/9320 @ 75/25 1.6874 106.1 45.37 65 0.777 0.751 0.718 7 AD 8181/SEP 688A @60/40 1.6873 102.6 45.37 64 0.774 0.747 0.719 8 8940/9320 @ 60/40 1.6873 102.9 45.46 64 0.767 0.745 0.714 9 AD 8181/SEP 688A @50/50 1.6866 99.3 45.40 62 0.769 0.741 0.715 8940/9320 @ 50/50 1.6868 101.2 45.40 61 0.765 0.735 0.710 11 AD 8181/SEP 688A @40/60 1.6865 98.1 45.18 61 0.767 0.745 0.711 12 8940/9320 @ 40/60 1.6871 99.1 45.40 59 0.759 0.732 0.700 13 8220/SEP 688A @50/50 1.6851 103.2 45.57 63 0.777 0.747 0.724 14 AD8172/SEP 688A @50/50 1.6856 97.8 45.53 60 0.768 0.736 0.711 8 - AS is conventional in the industry, the cover compositions of Table 2 also include a color concentrate or master batch which contains additional ionomer resin as well as the other ingredients of the cover. The percent by weight of ionomer resin of the cover compositions of Table 2 and of the claims does not include the ionomer resin of the color concentrate or master batch.

The cover composition was injection molded over the core in the conventional manner. Alternatively, and also conventionally, the cover material can be injection molded into hemispherical half shells, and two half shells can be compression molded over a core.

Composition Nos. 1 and 2 are non-blended hard ionomers and are included to provide the properties of those ionomers.

Composition No. 3 is a blend of 90% by weight AD 8181 hard Surlyn ionamer and 10% by weight SEP 688A Mg V.L.M.I. Surlyn ionomer.

Composition No. 4 is a prior art-blend of 90% by weight 8940 hard Surlyn ionomer and 10% by weight 9302 V.L.M.I. Surlyn ionomer. Composition No 3 has improved C.O.R. properties compared to Composition No. 4 with no loss of playability as measured by Shore D hardness and PGA Compression.

The Coefficient of Restitution of the golf balls in Table 2 is measured by propelling a ball at a given velocity against a hard surface, and measuring the inbound (given) and outbound velocity. The ratio of the outbound velocity to the - 9 inbound velocity is the coefficient of restitution. The higher the C. O.R., the more efficient the club/ball collision, and this will relate to ball performance (higher C.O.R. indicates higher Initial Velocity, and improved (longer) distance).

PGA compression is a standard industry test and is a measure of a golf ball's deflection at a specified load. A universal piece of testing equipment for measuring compression is an ATTI compression tester as purchased from Atti Engineering Corp. of Union City, New Jersey.

Composition No. 5 illustrates a 75:25 blend of hard ionomer with Mg V.L.M. l., and illustrates improved C.O.R. properties with no loss in playability (Shore 'D' PGA compression) properties compared to a prior art 75:25 blend (Composition No. 6) of a hard ionomer/V.L.M.I.

Composition No. 7 illustrates a 60:40 blend of hard ionomer with Mg V.L.M. I., and illustrates improved C.O.R. properties with no loss in playability (Shore 'D', PGA compression) properties compared to a prior art 60:40 blend (Composition No. 8) of a hard ionomer/V.L.M.I.

Composition No. 9 illustrates a 50:50 blend of hard ionomer with Mg V.L.M. I., and illustrates improved C.O.R. properties with no loss in playability (Shore 'D', PGA compression) properties compared to a prior art 50:50 (Composition No. 10) of a hard ionomer/V.L.M.I.

Composition No. 11 illustrates a 40:60 blend of hard ionomer with Mg V.L. M.I., and illustrates improved C.O.R.

- 10 properties with no loss in playability (Shore ODO, PGA compression) properties compared to a prior art 40:60 blend (Composition No. 12) of a hard ionomer/V.L.M.1

Composition Nos. 13 and 14 are further examples of blends of hard ionomers with Mg V.L.M.I., that further illustrates that blend of this invention shows improvement over prior art blend 10, at a hard ionomer/V. L.M.I. ratio of 50:50.

While in the foregoing specification a detailed description of specific embodiments of the invention were set forth for the purpose of illustration, it will be understood that many of the details herein given can be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

1 OW353GI-G

Claims (8)

1. A golf ball having a core and cover, the cover comprising a blend of hard ionomer resin(s) and a very low modulus ionomer resin neutralized with Mg ions, wherein:

the hard ionomer is a co-polymer of 75-85 by weight of an olefin with 15-25% by weight of an alpha, beta ethylenically unsaturated carboxylic acid having 10-90% of the carboxylic acid groups neutralized with a metal ion selected from the class of Na, Mg, Li, Zn, K and having a flexural'modulus of 40,000-100,000 psi, a shore fD' hardness of 65 or greater, and a melt index of 0.5-5.0g/10 min., and the very low modulus ionomer is a terpolymer consisting of 65-79% by weight of an olefin, 6-12% by weight of an alpha, beta ethylenically unsaturated carboxylic acid, and 15-25%.by weight of an unsaturated salt of an acrylate ester, where 10-90% of the carboxylic acid groups are neutralized with Mg ions, and having a flexural modulus of 3,00010,000 psi, a shore OD' hardness of 30-55, and a melt index of 0.5-5.0g/10 min.

2. A golf ball as claimed. in claim 1, in which the cover includes from 90 to 10 percent by weight o f hard ionomer resin and from 10 to 90 percent by weight of very low modulus ionomer resin.

3. A golf ball as claimed in claim 1 or 2, in which the cover includes from 75 to 25 percent by weight of hard ionomer resin and from 25 to 75 percent by weight of very low modulus ionomer resin.

- 12 by weight preceding percent by by weight

4. A golf ball as claimed in claim 1, 2 or 3, in which the cover includes from 60 to 40 percent by weight of hard ionomer resin and from 40 to 60 percent of very low modulus ionomer resin.

5. A golf ball as claimed in any one of the claims, in which the cover includes 50 weight of hard ionomer resin and 50 percent of very low modulus ionomer resin.

6. A golf ball as claimed in any one of the preceding claims, wherein the cover thickness is 0.06511-0.07511 and core diameter is 1.53511-1.54519.

7. A golf ball as claimed in claim 1, substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.

8. A golf ball as claimed in claim 7, with reference to and as illustrated in any one of the hereinbefore described cover compositions.