U.S. patent application number 10/103414 was filed with the patent office on 2003-04-10 for golf ball with vapor barrier layer and method of making same.
Invention is credited to Hogge, Matthew F., Lutz, Mitchell E., Sullivan, Michael J..
Application Number | 20030069085 10/103414 |
Document ID | / |
Family ID | 32716619 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030069085 |
Kind Code |
A1 |
Hogge, Matthew F. ; et
al. |
April 10, 2003 |
Golf ball with vapor barrier layer and method of making same
Abstract
A golf ball with at least one moisture vapor barrier layer is
disclosed. In accordance to one aspect of the invention, the
moisture vapor barrier layer may comprise butyl rubber. The butyl
rubber may also be a halogenated butyl rubber such as bromobutyl
rubber or chlorobutyl rubber. The butyl rubber may also be a
sulfonated butyl rubber. The butyl rubber may be blended with other
polymers. In accordance to another aspect of the invention, the
moisture vapor barrier layer is placed on to a core subassembly and
cured by infrared radiation (IR). IR-curable moisture vapor barrier
materials include, but not limited to, butyl rubber, polysulfide
rubber and single-pack castable polymers, among others. In
accordance to another aspect of the invention, an outer layer of
the golf ball may comprise a polymer that has a cured temperature
greater than the softening temperature or melting temperature of
the encased subassembly. Such outer layer may be cured by IR. The
outer layer may be a cover, an intermediate layer or a moisture
vapor barrier layer.
Inventors: |
Hogge, Matthew F.;
(Mattapoisett, MA) ; Lutz, Mitchell E.;
(Fairhaven, MA) ; Sullivan, Michael J.;
(Barrington, RI) |
Correspondence
Address: |
Troy R. Lester
Acushnet Company
333 Bridge Street
Fairhaven
MA
02719
US
|
Family ID: |
32716619 |
Appl. No.: |
10/103414 |
Filed: |
March 21, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10103414 |
Mar 21, 2002 |
|
|
|
09973342 |
Oct 9, 2001 |
|
|
|
Current U.S.
Class: |
473/371 ;
473/374; 473/378 |
Current CPC
Class: |
A63B 37/0006 20130101;
A63B 37/002 20130101; A63B 37/0033 20130101; C08L 81/04 20130101;
A63B 37/12 20130101; A63B 37/0003 20130101; A63B 37/0031 20130101;
A63B 37/0093 20130101 |
Class at
Publication: |
473/371 ;
473/374; 473/378 |
International
Class: |
A63B 037/04; A63B
037/06; A63B 037/12 |
Claims
What is claimed is:
1. A golf ball comprising a core, a moisture vapor barrier layer
and a cover, wherein the moisture barrier layer has a moisture
vapor transmission rate that is lower than that of the cover and
wherein the moisture vapor barrier layer comprises butyl
rubber.
2. The golf ball of claim 1, wherein the butyl rubber comprises a
halogenated butyl rubber.
3. The golf ball of claim 2, wherein the halogenated butyl rubber
is a bromobutyl rubber.
4. The golf ball of claim 2, wherein the halogenated butyl rubber
is a chlorobutyl rubber.
5. The golf ball of claim 1, wherein the butyl rubber is a
sulfonated butyl rubber.
6. The golf ball of claim 2, wherein the halogenated butyl rubber
is blended with a double bond-vulcanizable rubber.
7. The golf ball of claim 6, wherein the core comprises a diene
rubber.
8. The golf ball of claim 7, wherein the core comprises a
polybutadiene rubber.
9. The golf ball of claim 1, wherein the moisture vapor
transmission rate of the moisture vapor barrier layer is less than
the moisture vapor transmission rate of ionomer resin.
10. The golf ball of claim 1, wherein the moisture vapor
transmission rate of the moisture vapor barrier layer is less than
about 0.6 grams.multidot.mM/m.sup.2.multidot.day.
11. The golf ball of claim 1, wherein the moisture barrier layer
comprises filler.
12. The golf ball of claim 11, wherein the filler is selected from
a group consisting of aluminum, mica, micaceous iron oxide, metal,
ceramic and graphite.
13. The golf ball of claim 1, wherein the butyl rubber is blended
with ethylene propylene diene monomer rubber.
14. The golf ball of claim 1, wherein the butyl rubber is blended
with vinylidene chloride polymer.
15. A golf ball comprising a core, a moisture vapor barrier layer
and a cover, wherein the moisture barrier layer has a moisture
vapor transmission rate that is lower than that of the cover and
wherein the moisture vapor barrier comprises a brominated polymer,
wherein the brominated polymer comprises a copolymer of isobutylene
and p-methylstyrene.
16. The golf ball of claim 15, wherein the brominated polymer is
blended with a double bond-vulcanizable rubber.
17. The golf ball of claim 16, wherein the core comprises a diene
rubber.
18. The golf ball of claim 17, wherein the core comprises a
polybutadiene rubber.
19. The golf ball of claim 15, wherein the moisture vapor
transmission rate of the moisture vapor barrier layer is lower than
the moisture vapor transmission rate of ionomer resin.
20. The golf ball of claim 1, wherein the moisture vapor
transmission rate of the moisture vapor barrier layer is less than
about 0.6 grams.multidot.mm/m.sup.2.multidot.day.
21. The golf ball of claim 1, wherein the moisture barrier layer
comprises filler.
22. The golf ball of claim 21, wherein the filler is selected from
a group consisting of aluminum, mica, micaceous iron oxide, metal,
ceramic and graphite.
23. A golf ball comprising a core, a moisture vapor barrier layer
and a cover, wherein the moisture barrier layer has a moisture
vapor transmission rate that is lower than that of the cover and
wherein the moisture vapor barrier comprises polyisobutylene.
24. A golf ball comprising a core subassembly, an outer layer
encasing the core subassembly, wherein the outer layer comprises a
polymer having a crosslinking temperature that is higher than the
softening temperature of a portion of the core subassembly.
25. The golf ball of claim 24, wherein the crosslinking temperature
is higher than the melting temperature of a portion of the core
subassembly.
26. The golf ball of claim 24, wherein the core subassembly
comprises a core.
27. The golf ball of claim 26, wherein the core subassembly further
comprises at least an intermediate layer encasing the core.
28. The golf ball of claim 24, wherein the outer layer is a cover
layer.
29. The golf ball of claim 24, wherein the outer layer is an
intermediate layer.
30. The golf ball of claim 24, wherein the outer layer is a
moisture vapor barrier layer.
31. The golf ball of claim 24, wherein the outer layer is cured by
infrared radiation.
32. A golf ball comprising a core and a moisture vapor barrier
layer and a cover, wherein the moisture barrier layer has a
moisture vapor transmission rate that is lower than that of the
cover and wherein the moisture vapor barrier layer is cured by
infrared radiation.
33. The golf ball of claim 32, wherein the moisture vapor barrier
layer comprises butyl rubber.
34. The golf ball of claim 33, wherein the butyl rubber is a
halogenated butyl rubber.
35. The golf ball of claim 33, wherein the butyl rubber is a
sulfonated butyl rubber.
36. The golf ball of claim 32, wherein the moisture vapor barrier
layer comprises polysulfide rubber.
37. The golf ball of claim 32, wherein the moisture vapor barrier
layer comprises a single-pack castable polymer.
38. The golf ball of claim 37, wherein the single-pack castable
isocyanate comprises uretdione moiety.
39. The golf ball of claim 38, wherein the isocyanate is blended
with an amine or polyol.
40. The golf ball of claim 37, wherein the single-pack castable
isocyanate comprises blocked isocyanate.
41. The golf ball of claim 40, wherein the isocyanate is blended
with an amine or polyol.
42. The golf ball of claim 37, wherein the single-pack castable
polymer comprises 3,5 dimethylpyrazole (DMP) blocked-IPDI.
43. The golf ball of claim 1, wherein the cover has a Shore D
hardness of less than about 65.
44. The golf ball of claim 43, wherein the cover has a Shore D
hardness between about 30 and about 60.
45. The golf ball of claim 44, wherein the cover has a Shore D
hardness between about 35 and about 50.
46. The golf ball of claim 45, wherein the cover has a Shore D
hardness between about 40 and about 45.
47. The golf ball of claim 1, wherein the cover has a thickness
between about 0.010 inch to about 0.050 inch.
48. The golf ball of claim 47, wherein the cover has a thickness of
about 0.030.
49. The golf ball of claim 1, wherein the cover comprises a
thermoset polymer.
50. The golf ball of claim 49, wherein the thermoset polymer is
thermoset polyrrethane.
51. The golf ball of claim 49, wherein the thermoset polymer is
thermoset polyurethane ionomer.
52. The golf ball of claim 49, wherein the thermoset polymer is
thermoset polyurethane epoxy.
53. The golf ball of claim 1, wherein the cover comprises
thermoplastic polyurethane.
54. The golf ball of claim 1, wherein the core comprises
polybutadiene.
55. The golf ball of claim 1, wherein the core comprises a polymer,
wherein the polymer is selected from a group consisting of natural
rubber, polyisoprene, styrene-butadiene rubber,
styrene-propylene-diene rubber, ionomer resin, polyamide,
polyester, polyether amide copolymer, polyether ester copolymer,
thermoplastic urethane, styrenic block copolymers elastomer,
urethane, polyurea, epoxy, silicone, IPN, reaction injection molded
polyurethane, and reaction injection molded polyurea.
56. The golf ball of claim 1, wherein the moisture vapor barrier
layer is formed by spraying.
57. The golf ball of claim 1, wherein the moisture vapor barrier
layer is formed by dipping.
58. The golf ball of claim 1, wherein the moisture vapor barrier
layer is formed by casting.
59. The golf ball of claim 1, wherein the moisture vapor barrier
layer is formed by compression molding.
60. The golf ball of claim 1, wherein the moisture vapor barrier
layer is formed by injection molding.
Description
STATEMENT OF RELATED PATENT APPLICATION
[0001] This non-provisional, utility patent application is a
continuation-in-part of a co-pending patent application Ser. No.
09/973,342, entitled "Golf Ball With Vapor Barrier Layer and Method
of Making Same", filed on Oct. 9, 2001. The parent application is
hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a novel structure for a
golf ball, and more particularly to a golf ball with a moisture
vapor barrier layer.
BACKGROUND OF THE INVENTION
[0003] Solid core golf balls are well known in the art. Typically,
the core is made from polybutadiene rubber material, which provides
the primary source of resiliency for the golf ball. U.S. Pat. Nos.
3,241,834 and 3,313,545 disclose the early work in polybutadiene
chemistry. It is also known in the art that increasing the
cross-link density of polybutadiene can increase the resiliency of
the core. The core is typically protected by a cover from repeated
impacts from golf clubs. The golf ball may comprise additional
layers, which can be an outer core or an inner cover layer. One or
more of these additional layers may be a wound layer of stretched
elastic windings to increase the ball's resiliency.
[0004] A known drawback of polybutadiene cores cross-linked with
peroxide and/or zinc diacrylate is that this material is adversely
affected by moisture. Water moisture vapor reduces the resiliency
of the cores and degrades its properties. A polybutadiene core will
absorb water and loose its resilience. Thus, these cores must be
covered quickly to maintain optimum ball properties. The cover is
typically made from ionomer resins, balata, and urethane, among
other materials. The ionomer covers, particularly the harder
ionomers, offer some protection against the penetration of water
vapor. However, it is more difficult to control or impart spin to
balls with hard covers. Conventional urethane covers, on the other
hand, while providing better ball control, offer less resistance to
water vapor than ionomer covers.
[0005] Prolonged exposure to high humidity and elevated temperature
may be sufficient to allow water vapor to invade the cores of some
commercially available golf balls. For example at 110.degree. F.
and 90% humidity for a sixty day period, significant amounts of
moisture enter the cores and reduce the initial velocity of the
balls by 1.8 ft/s to 4.0 ft/s or greater. The change in compression
may vary from 5 PGA to about 10 PGA or greater. The absorbed water
vapor also reduces the coefficient of restitution (CoR) of the
ball.
[0006] Several prior patents have addressed the water vapor
absorption problem. U.S. Pat. No. 5,820,488 discloses a golf ball
with a solid inner core, an outer core and a water vapor barrier
layer disposed therebetween. The water vapor barrier layer
preferably has a water vapor transmission rate lower than that of
the cover layer. The water vapor barrier layer can be a
polyvinylidene chloride (PVDC) layer. It can also be formed by an
in situ reaction between a barrier-forming material and the outer
surface of the core. Alternatively, the water vapor barrier layer
can be a vermiculite layer. U.S. Pat. Nos. 5,885,172 and 6,132,324
disclose, among other things, a golf ball with a polybutadiene or
wound core with an ionomer resin inner cover and a relatively soft
outer cover. The hard ionomer inner cover offers some resistance to
water vapor penetration and the soft outer cover provides the
desirable ball control. Additionally, U.S. Pat. No. 5,875,891
discloses an impermeable packaging for golf balls. The impermeable
packaging acts as a moisture barrier limiting moisture absorption
by golf balls during storage, but not during use.
[0007] The moisture vapor barrier layer disclosed in the prior
patents can be rigid and makes the ball stiffer. Furthermore,
producing a rigid layer may cause significant production obstacles.
On the other hand, less rigid polymers, such as butyl rubber and
other rubbers, are known to have low permeability to air, gases and
moisture. Butyl rubber is widely used as sealant for rooftops, as
inner liner in tubeless tires, and as lining for chemical tanks,
among other uses. In the golf ball art, butyl rubber's usage has
been limited to practice balls or driving range balls due to its
slow initial velocity and low CoR, as discussed in U.S. Pat. Nos.
5,209,485 and 4,995,613. Butyl rubber is also used as the outermost
cover layer or a part of the cover due to its durability, as
disclosed, in U.S. Pat. Nos. 5,873,796 and 5,882,567, among others.
However, the moisture vapor barrier advantage of butyl rubber has
not heretofore been utilized in the golf ball art to make a better
performing golf ball.
[0008] Also, high-temperature curing of certain polymeric materials
to form the water vapor barrier layer or other outer layers on the
golf ball is difficult to accomplish, since such curing or
crosslinking heats the entire golf ball subassembly. This heating
method may degrade the untargeted components or layers within the
subassembly. Additionally, this curing method limits suitable outer
layer materials to materials having a cured temperature that is
lower than the softening temperature or lower melting temperature
of the inner layers or core.
[0009] Hence, there remains a need for a golf ball with an improved
water vapor barrier layer and improved methods for applying a water
vapor barrier layer on to the core of the golf ball.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to a golf ball comprising
a layer of moisture vapor barrier with a moisture vapor
transmission rate preferably lower than that of the cover.
Preferably, the moisture vapor barrier layer comprises butyl
rubber. The butyl rubber may also be a halogenated butyl rubber
such as bromobutyl rubber or chlorobutyl rubber. The butyl rubber
may also be a sulfonated butyl rubber. The butyl rubber may be
blended with other polymers, such as double bond-vulcanizable
rubber, ethylene propylene diene monomer rubber and vinylidene
chloride.
[0011] The present invention is also directed to a golf ball
comprising a moisture vapor barrier layer, which comprises
copolymer of isobutylene and p-methylstyrene or
polyisobutylene.
[0012] In accordance to another aspect of the invention, the
moisture vapor barrier layer is placed on to a core subassembly and
cured by infrared radiation (IR). IR-curable moisture vapor barrier
materials include, but not limited to, butyl rubber, polysulfide
rubber and single-pack castable polymers, among others.
[0013] In accordance to another aspect of the invention, an outer
layer of the golf ball may comprise a polymer that has a cured
temperature greater than the softening temperature or melting
temperature of the encased subassembly. Such outer layer may be
cured by IR. The outer layer may be a cover, an intermediate layer
or a moisture vapor barrier layer.
[0014] The present invention is also directed to a golf ball
comprising a butyl rubber moisture vapor barrier and a relatively
soft cover. Preferably, the soft cover has a Shore D of less than
65 or between about 30 and about 60, and more preferably between
about 35 and about 50, and most preferably about 40 and about 45.
The cover preferably has a thickness of between about 0.010 inch to
about 0.050 inch, and more preferably about 0.030 inch. The cover
preferably comprises a thermoset polymer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the accompanying drawings which form a part of the
specification and are to be read in conjunction therewith and in
which like reference numerals are used to indicate like parts in
the various views:
[0016] FIG. 1 is a front view of a dimpled golf ball in accordance
to the present invention;
[0017] FIG. 2 is a cross-sectional view of the golf ball in FIG. 1
showing a solid core surrounded by a thin moisture vapor barrier
layer and a cover; and
[0018] FIG. 3 is a cross-sectional view of another golf ball in
accordance to the present invention showing a solid core with
multiple wound layers surrounded by a thin moisture vapor barrier
layer.
DETAILED DESCRIPTION OF THE INVENTION
[0019] As shown generally in FIGS. 1 and 2, where like numbers
designate like parts, reference number 10 broadly designates a golf
ball in accordance to the present invention. Golf ball 10
preferably has a solid core 12, an intermediate layer 14 and a
cover 16. Solid core 12 may comprise a single spherical element, or
it may comprise a spherical element with one or more intermediate
layers surrounding the spherical element. Solid core 12 can be made
from any suitable core materials including thermoset plastics, such
as natural rubber, polybutadiene (PBD), polyisoprene,
styrene-butadiene or styrene-propylene-diene rubber, and
thermoplastics such as ionomer resins, polyamides, polyesters, or a
thermoplastic elastomer. Suitable thermoplastic elastomers include
Pebax.RTM., which is believed to comprise polyether amide
copolymers, Hytrel.RTM., which is believed to comprise polyether
ester copolymers, thermoplastic urethane, and Kraton.RTM., which is
believed to comprise styrenic block copolymers elastomers. These
products are commercially available from Elf-Atochem, E. I. Du Pont
de Nemours and Company, various manufacturers, and Shell Chemical
Company, respectively. The core materials can also be formed from a
castable material. Suitable castable materials include those
comprising a urethane, polyurea, epoxy, silicone, IPN's, etc.
[0020] Additionally, suitable core materials may also include a
reaction injection molded polyurethane or polyurea, including those
versions referred to as nucleated, where a gas, typically nitrogen,
is incorporated via intensive agitation or mixing into at least one
component of the polyurethane, typically, the pre-polymer, prior to
component injection into a closed mold where essentially full
reaction takes place resulting in a cured polymer having reduced
specific gravity. These materials are referred to as reaction
injection molded (RIM) materials. Alternatively, the core may have
a liquid center.
[0021] Cover 16 is preferably tough, cut-resistant, and selected
from conventional materials used as golf ball covers based on the
desired performance characteristics. The cover may comprise one or
more layers. Suitable cover materials include ionomer resins, such
as Surlyn.RTM. available from DuPont, blends of ionomer resins,
thermoplastic or thermoset urethane, acrylic acid, methacrylic
acid, thermoplastic rubber polymers consisting of block copolymers
in which the elastomeric midblock of the molecule is an unsaturated
rubber or a saturated olefin rubber, e.g., Kraton.RTM. rubbers
available from Shell Chemical Co., polyethylene, and synthetic or
natural vulcanized rubber such as balata.
[0022] Additionally, other suitable core and cover materials are
disclosed in U.S. Pat. No. 5,919,100 and international publications
WO 00/23519 and WO 01/29129. These disclosures are incorporated by
reference in their entirety. Preferably, core 12 is made from a
polybutadiene rubber material and cover 16 is made from a
composition comprising a thermoset or thermoplastic urethane or a
composition comprising an ionomer resin.
[0023] To prevent or minimize the penetration of moisture,
typically water vapor, into core 12 of golf ball 10, intermediate
layer 14 comprises a moisture vapor barrier layer preferably
disposed around core 12. Preferably, moisture vapor barrier layer
14 has a moisture vapor transmission rate that is lower than that
of the cover, and more preferably less than the moisture vapor
transmission rate of an ionomer resin such as Surlyn.RTM. which is
in the range of about 0.45 to about 0.95
grams.multidot.mm/m.sup.2.multidot.day. Typically, the moisture
vapor transmission rate of ionomer resin is less than 0.6
grams.multidot.mm/m.sup.2.multidot.day as reported in "Permeability
and other Film Properties of Plastics and Elastomer" published by
the Plastic Design Library (1995). The moisture vapor transmission
rate is defined as the mass of moisture vapor that diffuses into a
material of a given thickness per unit area per unit time. The
preferred standards of measuring the moisture vapor transmission
rate include ASTM F1249-90 entitled "Standard Test Method for Water
Vapor Transmission Rate Through Plastic Film and Sheeting Using a
Modulated Infrared Sensor," and ASTM F372-94 entitled "Standard
Test Method for Water Vapor Transmission Rate of Flexible Barrier
Materials Using an Infrared Detection Technique," among others.
[0024] A preferred polymer for the moisture vapor barrier layer is
butyl rubber. Butyl rubber (IIR) is an elastomeric copolymer of
isobutylene and isoprene. Detailed discussions of butyl rubber are
provided in U.S. Pat. Nos. 3,642,728, 2,356,128 and 3,099,644. The
disclosures of these references are incorporated herein by
reference in their entireties. Butyl rubber is an amorphous,
non-polar polymer with good oxidative and thermal stability, good
permanent flexibility and high moisture and gas resistance.
Generally, butyl rubber includes copolymers of about 70% to 99.5%
by weight of an isoolefin, which has about 4 to 7 carbon atoms,
e.g., isobutylene, and about 0.5% to 30% by weight of a conjugated
multiolefin, which has about 4 to 14 carbon atoms, e.g., isoprene.
The resulting copolymer contains about 85% to about 99.8% by weight
of combined isoolefin and 0.2% to 15% of combined multiolefin.
Commercially available butyl rubbers, such as those manufactured by
ExxonMobil Chemical Company, typically have about 1 to 2.5 mole
percent of isoprene. Butyl rubbers generally have molecular weight
of about 20,000 to about 500,000. Suitable butyl rubber is also
available from United Coatings under the tradename Elastron.TM.
858. Elastrom 858 is a butyl rubber coating applied as a solution
in a volatile hydrocarbon solvent, which is typically sprayed or
dipped on to an object or a surface, and contains lead peroxide as
a crosslinking agent.
[0025] Butyl rubbers are also available in halogenated form.
Halogenated butyl rubbers may be prepared by halogenating butyl
rubber in a solution containing inert C3-C5 hydrocarbon solvent,
such as pentane, hexane or heptane, and contacting this solution
with a halogen gas for a predetermined amount of time, whereby
halogenated butyl rubber and a hydrogen halide are formed. The
halogenated butyl rubber copolymer may contain up to one halogen
atom per double bond. Halogenated butyl rubbers or halobutyl
rubbers include bromobutyl rubber, which may contain up to 3%
reactive bromine, and chlorobutyl rubber, which may contain up to
3% reactive chlorine. Halogenated butyl rubbers are also available
from ExxonMobil Chemical. Butyl rubbers and halogenated rubbers
advantageously have low permeability to air, gases and moisture.
For example, as reported by the manufacturer the permeability of
nitrogen in butyl rubber is more than one order of magnitude less
than that in neoprene, styrene butadiene rubber, natural rubber and
nitrile butadiene rubber.
[0026] Butyl rubber is also available in sulfonated form, such as
those disclosed in the '728 patent and in U.S. Pat. No. 4,229,337.
Generally, butyl rubber having a viscosity average molecular weight
in the range of about 5,000 to 85,000 and a mole percent
unsaturation of about 3% to about 4% may be sulfonated with a
sulfonating agent comprising a sulfur trioxide (SO.sub.3) donor in
combination with a Lewis base containing oxygen, nitrogen or
phosphorus. The Lewis base serves as a complexing agent for the
SO.sub.3 donor. SO.sub.3 donor includes compound containing
available SO.sub.3, such as chlorosulfonic acid, fluorosulfonic
acid, sulfuric acid and oleum.
[0027] Typically, the moisture vapor transmission rate of butyl
rubber is in the range of about 0.001 to about 0.100
grams.multidot.mm/m.sup.2.mult- idot.day.
[0028] Other suitable moisture vapor barrier polymers include the
elastomers that combine the low permeability of butyl rubbers with
the environmental and aging resistance of ethylene propylene diene
monomer rubbers (EPDM), commercially available as Exxpro.TM. from
ExxonMobil Chemical. More specifically, these elastomers are
brominated polymers derived from a copolymer of isobutylene (IB)
and p-methylstyrene (PMS). Bromination selectively occurs on the
PMS methyl group to provide a reactive benzylic bromine
functionality. Another suitable moisture vapor barrier polymer is
copolymer of isobulyline and isoprene with a styrene block
copolymer branching agent to improve manufacturing
processability.
[0029] Another suitable moisture vapor barrier polymer is
polyisobutylene. Polyisobutylene is a homopolymer, which is
produced by cationic polymerization methods. Commercially available
grades of polyisobutylene, under the tradename Vistanex.TM. also
from ExxonMobil Chemical, are highly paraffinic hydrocarbon
polymers composed on long straight chain molecules containing only
chain-end olefinic bonds. An advantage of such elastomer is the
combination of low permeability and chemical inertness to resist
moisture vapor encroachment, and chemical or oxidative attacks.
Polyisobutylene is available as a viscous liquid or semi-solids,
and can be dissolved in certain hydrocarbon solvents.
[0030] In accordance to another aspect of the invention,
halogenated butyl rubber can be blended with a second rubber,
preferably a double bond-vulcanizable rubber, in a specific mixing
ratio in a two-step kneading process and then cured to form a
rubber blend that has low air/vapor permeability and high adhesion
to diene rubbers. A clear advantage of this rubber blend is that it
provides enhanced adherence to a polybutadiene core or subassembly
to provide an enhanced moisture/water vapor barrier layer. This
rubber blend is discussed in U.S. Pat. No. 6,342,567 B2. The '567
patent is hereby incorporated herein by reference. Alternatively, a
brominated isobutylene/p-methylstyrene, discussed above, can be
used in place of the halogenated rubber. Other moisture vapor
barrier polymers include thermoplastic elastomer blends that may be
dynamically vulcanized and comprise a butyl rubber or a halogenated
butyl rubber, such as those discussed in U.S. Pat. Nos. 6,062,283,
6,334,919 B1 and 6,346,571 B1. These references are incorporated
herein by reference. Alternatively, butyl rubber may be blended
with a vinylidene chloride polymer, i.e., saran, as disclosed in
U.S. Pat. No. 4,239,799. The '799 patent is also incorporated
herein by reference.
[0031] Butyl rubbers can be cured by a number of curing agents.
Preferred curing agents for golf ball usage include sulphur for
butyl rubber, and a peroxide curing agent, preferably zinc oxide,
for halogenated butyl rubbers. Other suitable curing agents may
include antimony oxide, lead oxide or lead peroxide. Lead based
curing agents may be used when appropriate safety precautions are
implemented. Butyl rubbers are commercially available in various
grades from viscous liquid to solids with varying the degree of
unsaturation and molecular weights. Latex grades are also
available.
[0032] Butyl rubber and halogenated rubber can be processed by
milling, calendering, extruding, injection molding and compression
molding, among other techniques. These processing techniques can
produce a semi-cured sheets or half-shelves of the moisture vapor
barrier material, which can be wrapped around a core or a core
subassembly. The moisture vapor barrier can be fully cured by
exposure to heat at elevated temperatures typically in the range of
about 250.degree. F. to 2000.degree. F.
[0033] Additionally, any number of fillers, additives, fibers and
flakes, such as mica, micaceous ion oxide, metal, ceramic,
graphite, aluminum or more preferably leafing aluminum, can be
incorporated into the moisture vapor barrier layer to create a
physical barrier, i.e., a more tortuous path, against moisture
vapor encroachment.
[0034] In accordance to another aspect of the invention. The curing
of the moisture vapor barrier material on to the core or the core
subassembly is preferably accomplished by infrared radiation (IR).
IR advantageously heats the moisture vapor material, e.g., butyl
rubber, locally without penetrating the underlying golf ball core
and/or other encased layers. Hence, the predetermined properties of
the core and/or of the encased layers would not be affected by the
heating/curing of the moisture vapor barrier layer. U.S. Pat. No.
6,174,388 B1 discloses that IR can be used effectively to heat and
cure the surface of a polymeric object while leaving the other
portions of the object unchanged. U.S. Pat. Nos. 5,677,362 and
5,672,393 disclose that IR heating can be used in conjunction with
ultraviolet heating to cure polymers effectively. The disclosure of
the patents are incorporated by reference in their entireties.
[0035] Another advantage of using IR as the curing technique is
that suitable moisture vapor barrier polymers, which have cured or
cross-linking temperatures that are higher than the softening
temperature or the melting temperature of the materials encased
therein, can be now employed as the moisture vapor barrier layer
and/or other outer layers.
[0036] In accordance to another aspect of the present invention,
another suitable IR-cured water vapor barrier material is
polysulfide rubber including those disclosed in U.S. Pat. Nos.
4,263,078 and 4,165,425, among others. These references are
incorporated herein by reference. In one example, the polysulfide
rubber is cured with lower alkyl tin oxide, such as di-n-butyl tin
oxide, and used in hot applied processes as disclosed in the '425
patent. This particular polysulfide rubber is thiol terminated and
cured with the lower alkyl tin oxide at temperatures between
100.degree. C. and 300.degree. C. to become a solid thermoplastic
elastomer that can be softened by heating and then cast or
injection molded into a water vapor barrier layer. This polysulfide
compound is preferably cured by IR.
[0037] Another suitable IR-curable polysulfide rubber is based on
thiol terminated liquid polysulfide polymer cured with zinc oxide
and a sulfur containing compound selected from
2-mercaptobenzothiazol, zinc lower alkyl dithiocarbamate and alkyl
thiuram polysulfides at temperatures from about 200.degree. F. to
about 390.degree. F. Agents, which improve the flowing properties
of the composition, such as copolymers of styrene and alkylenes,
organic or inorganic reinforcing fibrous materials, phenolic
resins, coumarone-indene resins, antioxidants, heat stabilizers,
polyalkylene polymers, factice, terpene resins, terpene resins
esters, benzothiazyl disulfide or diphenyl guanidine, can also be
added to the composition. Advantageously, this polysulfide rubber
possesses a good ability to wet the substrate and forms good bonds
with such substrate when cooled and, therefore, is a preferred
sealant for the golf ball core. This polysulfide compound is also
preferably cured by IR.
[0038] Moisture vapor barrier layer comprising polysulfide rubber
is fully disclosed in co-pending patent application entitled "Golf
Ball With Vapor Barrier Layer and Method for Making Same" filed on
the same day as the present application and assigned to the same
assignee. The disclosure of this co-pending patent application is
incorporated herein by reference.
[0039] In accordance to another aspect of the present invention,
suitable IR-cured water vapor barrier polymers include single-pack
castable polymers. A preferred single-pack polymer uses uretdiones
or blocked isocyanates to form a single-pack urethane component.
The single-pack blocked isocyanate system, which preferably
comprises isocyanate combined with an amine or poloyl, is
advantageously stable at room temperature. The application of heat,
such as infrared radiation, causes the isocyanate to become
unblocked or to react to form a urethane. No mixing or dynamically
controlling the ratios of the components is required.
[0040] Uretdione castable materials can be pre-formulated as a
single-pack system without premature reaction. The mixed
single-pack material can be directly injected or poured into a
mold, avoiding metering and mixing of multiple components. Parts
can be made utilizing viscous or solid materials that previously
could not be used with traditional two-pack systems.
Advantageously, uretdiones and blocked isocyanates when combined
with suitable reactive components can be milled into rubber stock
for use with other manufacturing techniques, discussed above.
[0041] A non-limiting example of a single-pack system in accordance
to the present invention is as follows. Finely ground uretdione is
dispersed in a liquid polyol or polyamine in combination with a tin
catalyst and cyclic amidine catalyst. A slurry is created. The
slurry mixture is poured into a suitable golf ball mold to make the
required part, e.g., core, intermediate layer or cover. The mold is
then heated to reach the predetermined deblocking temperature of
about 150-180.degree. C., and the reaction is allowed sufficient
time to complete. The cured component then can be removed from the
mold for further processing, if necessary.
[0042] In another example, 3,5 dimethylpyrazole (DMP) blocked-IPDI
is used in place of the uretdione in the above example. The mold is
then heated to the deblocking temperature of about 140-160.degree.
C., and the reaction is allowed sufficient time to complete. In
another non-limiting example, the single-pack moisture vapor
barrier layer utilizes blocked isocyanates that volatilize when
de-blocking occurs, such as diethylmaleonate (DEM) or methyl ethyl
ketoxime (MEKO) blocked hexamethylene diisocyanate cyclic trimer.
Such an example could be sprayed or dipped onto the golf ball core,
subassembly or the like and then followed with an IR cure.
[0043] Non-limiting chemical structures of the single-pack system
are shown below:
[0044] Formation of uretdiones: 1
[0045] Preferred chemical structure of polyuretdione cross-linker:
2
[0046] The preferred hardeners are uretdiones or a blocked
isocyanates, where the blocking agent remains in the component as a
solid once cast, such as DMP or triazole blocked isocyanates. The
structures of the preferred blocking agents are: 3
[0047] Single-pack castable water vapor barrier material is fully
disclosed in parent application Ser. No. 09/973,342, which has been
incorporated by referenced.
[0048] In accordance to one aspect of the invention, the Shore D
hardness values for the core and moisture vapor barrier
sub-assemblies have been measured less than about 60 and more
specifically in the range of about 5-50. Alternatively, according
to other aspects of the invention, the moisture barrier
sub-assemblies may have Shore D hardness value of greater than 50,
when more rigid materials, such as stiff ionomer with a Shore D
hardness of greater than 55 are used in conjunction with the
moisture vapor barrier layer 14.
[0049] Preferably, a golf ball in accordance to the present
invention comprises a solid or multiple-layer solid polybutadiene
core 12 having an outer diameter of greater than about 1.50 inches,
more preferably 1.550 inches and most preferably about 1.580
inches. Moisture vapor barrier layer 14 has a thickness preferably
in the range of about 0.001 inch to about 0.100 inch, more
preferably in range of about 0.010 inch to about 0.050 inch and
cover 16 is a urethane cover with sufficient thickness to produce a
1.680 inch diameter golf ball.
[0050] More preferably, the moisture vapor barrier layer is a thin
layer of suitable butyl rubber polymers discussed above, preferably
less than 0.050 inch, more preferable less than 0.030 inch and most
preferably less than 0.010 inch. It is also preferable that the
butyl rubber moisture vapor barrier layer would not significantly
and negatively affect the coefficient of restitution of the golf
ball. Preferably, the polybutadiene core 12 and the thin butyl
rubber moisture vapor barrier layer 14 are covered by a relatively
soft polymer cover having a thickness from about 0.010 to about
0.050 inch, more preferably about 0.030 inch and has a Shore D of
less than 65 or from about 30 to about 60, more preferably from
about 35 to about 50 and even more preferably about 40 to about 45.
Such a cover is fully disclosed in U.S. Pat. Nos. 5,885,172 and
6,132,324. The disclosures of these two patents are incorporated
herein by reference in their entireties. Preferred cover polymers
include thermoset urethanes and polyurethanes, thermoset urethane
ionomers and thermoset urethane epoxies.
[0051] In accordance to yet another aspect of the invention, as
shown in FIG. 3 golf ball 20 may have multiple layer core 12a, 12b
and 12c, surrounded by intermediate layer 14 and dimpled cover 16.
Core layers 12b and 12c may be an integral solid layer or discrete
layers molded on each other. Alternatively, both outer core layers
12b and 12c could be wound layers, or one of these two layers may
be a wound layer, and the innermost core 12a may be
liquid-filled.
[0052] While various descriptions of the present invention are
described above, it is understood that the various features of the
present invention can be used singly or in combination thereof.
Therefore, this invention is not to be limited to the specifically
preferred embodiments depicted therein.
* * * * *