Methods for making golf ball covers based on liquid ethylene-propylene diene copolymer rubbers and resulting balls

Patent metadata

Field	Value
Publication number	US-2016346625-A1
Application number	US-201615231872-A
Country	US
Kind code	A1
Filing date	Aug 9, 2016
Priority date	Mar 4, 2010
Publication date	Dec 1, 2016
Grant date	—

Abstract

Methods for making multi-piece golf balls comprising at least one component made of ethylene-propylene diene copolymer (EPDM) rubber and the resulting balls are provided. The multi-piece golf ball includes a cover, preferably a dual-cover having inner and outer cover layers. The outer cover is preferably made of a liquid rubber composition based on liquid EPDM rubber. In one version, the ball sub-assembly is dipped in a bath containing liquid EPDM rubber to form the outer cover. In another version, a casting method is used and the liquid EPDM rubber is dispensed into mold cavities to form the outer cover. The inner core of the ball may be made of polybutadiene rubber and the outer core layer may be made of EPDM rubber. The resulting golf ball has high resiliency, a soft feel, and good weatherability.

First claim

We claim:

1 . A multi-layered golf ball, comprising:
a ball sub-assembly comprising a solid core of at least one layer and surrounding inner cover layer, the inner cover having a material hardness in the range of about 60 to about 90 Shore D; and an outer cover layer disposed about the sub-assembly, the outer cover layer being formed from a first thermoset rubber composition comprising liquid ethylene-propylene-diene copolymer rubber, and the outer cover having a material hardness in the range of about 20 to about 80 Shore D, the material hardness of the inner cover being greater than the material hardness of the outer cover.

2 . The golf ball of claim 1 , wherein the core is single-layered, the core being formed from a second thermoset rubber composition.

3 . The golf ball of claim 2 , wherein the second thermoset rubber composition comprises a rubber selected from the group consisting of polybutadiene, ethylene-propylene-diene rubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, butyl rubber, halobutyl rubber, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and mixtures thereof.

4 . The golf ball of claim 1 , wherein the core is dual-layered, the core comprising an inner core and outer core layer, the inner core being formed from a second thermoset rubber composition, and the outer core layer being formed from a third thermoset rubber composition.

5 . The golf ball of claim 4 , wherein the third thermoset rubber composition comprises a rubber selected from the group consisting of polybutadiene, ethylene-propylene-diene rubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, butyl rubber, halobutyl rubber, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and mixtures thereof.

6 . The golf ball of claim 1 , wherein the outer core has a surface hardness and the inner core has a surface hardness, the hardness of the outer core surface being greater than the hardness of the inner core surface.

7 . The golf ball of claim 6 , wherein the outer core has surface hardness of 80 Shore C or greater and the inner core has a surface hardness of 70 Shore C or greater.

8 . The golf ball of claim 1 , wherein the inner cover layer is formed from an ionomeric resin comprising a copolymer of α-olefin, C 3 to C 8 α, β-ethylenically unsaturated mono- or dicarboxylic acid, and optional softening monomer.

9 . The golf ball of claim 1 , wherein the outer cover layer has a midpoint hardness and outer hardness surface, the hardness of the outer surface being greater than the hardness of the midpoint to define a positive hardness gradient.

10 . The golf ball of claim 9 , wherein the hardness of the outer cover surface is in the range of about 35 to about 90 Shore D and the hardness of the midpoint is in the range of about 30 to about 80 Shore D.

11 . The golf ball of claim 1 , wherein the outer cover layer has a midpoint hardness and outer hardness surface, the hardness of the outer surface being the same or greater than the hardness of the midpoint to define a zero or negative hardness gradient.

12 . The method of claim 11 , wherein the hardness of the outer cover midpoint is in the range of about 40 to about 75 Shore D and the hardness of the outer surface is in the range of about 35 to about 70 Shore D.

13 . A method for making a multi-piece golf ball, comprising the steps of:
a) dispensing a liquid rubber composition comprising liquid ethylene-propylene diene copolymer rubber into upper and lower mold members, the upper and lower mold members defining a mold cavity with a dimple pattern; b) placing a ball sub-assembly into the mold cavity; c) applying heat and pressure to the mold members so the composition encapsulates the sub-assembly and forms an outer cover having a dimpled pattern, and d) removing the multi-piece golf ball from the mold.

14 . The method of claim 13 , wherein the ethylene-propylene diene copolymer comprises ethylidene norborene diene monomer or dicyclopentadiene.

15 . The method of claim 13 , wherein the rubber composition is cured by peroxide-curing, sulfur-curing, high-energy radiation, or combinations thereof.

16 . The method of claim 13 , wherein the rubber composition further comprises peroxide.

17 . The method of claim 13 , wherein the rubber composition further comprises zinc diacrylate.

18 . The method of claim 13 , wherein the liquid rubber composition has a viscosity of 10,000 cp or less.

Assignees

• Acushnet Co

Inventors

• Sullivan Michael J
• Bulpett David A
• Comeau Brian
• Blink Robert
• Binette Mark L

Classifications

• A63B37/0076

  Multi-piece balls, i.e. having two or more intermediate layers · CPC title

• A63B37/02 Primary

  Special cores {(balls with finger holes A63B37/0001, golf ball cores A63B37/005)} · CPC title

• A63B37/0075

  Three piece balls, i.e. cover, intermediate layer and core · CPC title

• A63B37/0004

  Surface depressions or protrusions · CPC title

• A63B37/00621

  Centre hardness · CPC title