U.S. patent application number 14/992002 was filed with the patent office on 2016-05-05 for multi-layer core golf ball having opposing hardness gradient with steep gradient outer core layer.
This patent application is currently assigned to Acushnet Company. The applicant listed for this patent is Acushnet Company. Invention is credited to Brian Comeau, Derek A. Ladd, Michael J. Sullivan.
Application Number | 20160121174 14/992002 |
Document ID | / |
Family ID | 40221890 |
Filed Date | 2016-05-05 |
United States Patent
Application |
20160121174 |
Kind Code |
A1 |
Sullivan; Michael J. ; et
al. |
May 5, 2016 |
MULTI-LAYER CORE GOLF BALL HAVING OPPOSING HARDNESS GRADIENT WITH
STEEP GRADIENT OUTER CORE LAYER
Abstract
A golf ball comprising an inner core formed from a substantially
homogenous composition such that the geometric center hardness is
about 56 to 80 Shore C. An outer core layer has an outer surface
having hardness of about 85 to 98 Shore C and an inner surface
hardness of about 68 to 78 Shore C and being formed from a second
homogenous rubber composition. A cover layer is formed over the
outer core layer. The hardness of the second outer surface is
greater than the hardness of the inner surface to define a positive
hardness gradient of about 7 to 30 Shore C, and the hardness of the
first outer surface is lower than the hardness of the geometric
center to define a negative hardness gradient of about 1 to 15
Shore C.
Inventors: |
Sullivan; Michael J.; (Old
Lyme, CT) ; Ladd; Derek A.; (Acushnet, MA) ;
Comeau; Brian; (Berkley, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Assignee: |
Acushnet Company
Fairhaven
MA
|
Family ID: |
40221890 |
Appl. No.: |
14/992002 |
Filed: |
January 10, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14570110 |
Dec 15, 2014 |
9259621 |
|
|
14992002 |
|
|
|
|
14059718 |
Oct 22, 2013 |
8911305 |
|
|
14570110 |
|
|
|
|
13602515 |
Sep 4, 2012 |
8562461 |
|
|
14059718 |
|
|
|
|
13195083 |
Aug 1, 2011 |
8257200 |
|
|
13602515 |
|
|
|
|
12891283 |
Sep 27, 2010 |
7988570 |
|
|
13195083 |
|
|
|
|
12177227 |
Jul 22, 2008 |
7744489 |
|
|
12891283 |
|
|
|
|
12177203 |
Jul 22, 2008 |
7909709 |
|
|
12177227 |
|
|
|
|
11832163 |
Aug 1, 2007 |
7429221 |
|
|
12177203 |
|
|
|
|
11829461 |
Jul 27, 2007 |
7537530 |
|
|
11832163 |
|
|
|
|
11772903 |
Jul 3, 2007 |
7537529 |
|
|
11829461 |
|
|
|
|
Current U.S.
Class: |
473/374 |
Current CPC
Class: |
A63B 37/0092 20130101;
A63B 37/0051 20130101; A63B 37/0032 20130101; A63B 37/0062
20130101; A63B 37/0045 20130101; A63B 37/0064 20130101; A63B
37/0044 20130101; A63B 37/0043 20130101; A63B 37/0075 20130101;
A63B 37/0063 20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00 |
Claims
1. A golf ball comprising: an inner core layer having an outer
diameter of about 0.50 to 1.55 inches, a first outer surface, and a
geometric center, the inner core layer comprising a first
substantially homogenous composition such that the geometric center
has a hardness of about 51 to 76 Shore C; an outer core layer
disposed about the inner core layer, the outer core layer having an
outer diameter of about 1.30 to 1.62 inches, a second outer surface
having a hardness of about 85 to 98 Shore C, and comprising a
second substantially homogenous rubber composition; and a cover
layer disposed about the outer core layer; wherein the geometric
center and the first and second outer surfaces each have a
hardness, the hardness of the second outer surface being greater
than the hardness of the geometric center to define a positive
hardness gradient of about 7 to 30 Shore C.
2. The golf ball of claim 1, wherein the inner core has an outer
diameter of about 0.75 inches to 1.50 inches.
3. The golf ball of claim 2, wherein the inner core has an outer
diameter of about 1.00 inch to 1.40 inches.
4. The golf ball of claim 1, wherein the outer core layer has an
outer diameter of about 1.40 inches to 1.60 inches.
5. The golf ball of claim 4, wherein the outer core layer has an
outer diameter of about 1.50 inches to 1.59 inches
6. The golf ball of claim 1, wherein the hardness of the geometric
center is about 68 Shore C to 76 Shore C.
7. The golf ball of claim 1, wherein the cover layer comprises an
inner cover layer and an outer cover layer.
8. The golf ball of claim 7, wherein the inner cover layer
comprises a high acid ionomer comprising a copolymer of ethylene
and methacrylic or acrylic acid and having an acid content of at
least 16 to about 25 weight percent.
9. The golf ball of claim 1, wherein the cover layer comprises a
thermoset or thermoplastic polyurethane material.
10. The golf ball of claim 1, wherein the first composition
comprises an antioxidant in an amount of about 0.1 pph to 1.0 pph.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 14/570,110, filed Dec. 15, 2014, which is a
divisional of U.S. patent application Ser. No. 14/059,718, filed
Oct. 22, 2013 and now U.S. Pat. No. 8,911,305, which is a
continuation of U.S. patent application Ser. No. 13/602,515, filed
Sep. 4, 2012 and now U.S. Pat. No. 8,562,461, which is a
continuation of U.S. patent application Ser. No. 13/195,083, filed
Aug. 1, 2011 and now U.S. Pat. No. 8,257,200, which is a
continuation of U.S. patent application Ser. No. 12/891,283, filed
Sep. 27, 2010 and now U.S. Pat. No. 7,988,570, which is a
continuation of U.S. patent application Ser. No. 12/177,227, filed
Jul. 22, 2008 and now U.S. Pat. No. 7,744,489, which is a
continuation-in-part of U.S. patent application Ser. No.
12/177,203, filed Jul. 22, 2008 and now U.S. Pat. No. 7,909,709,
which is a continuation-in-part of U.S. patent application Ser. No.
11/832,163, filed Aug. 1, 2007 and now U.S. Pat. No. 7,429,221,
which is a continuation-in-part of U.S. patent application Ser. No.
11/829,461, filed Jul. 27, 2007 and now U.S. Pat. No. 7,537,530,
which is a continuation-in-part of U.S. patent application Ser. No.
11/772,903, filed Jul. 3, 2007 and now U.S. Pat. No. 7,537,529; the
disclosures of which are incorporated herein in their entirety.
FIELD OF THE INVENTION
[0002] This invention relates generally to multi-layer golf ball
cores formed from at least one component having a surface hardness
less than the center hardness so as to be defined by a "negative"
hardness gradient and a second component having a steep "positive"
hardness gradient.
BACKGROUND OF THE INVENTION
[0003] Solid golf balls are typically made with a solid core
encased by a cover, both of which can have multiple layers, such as
a dual core having a solid center and an outer core layer, or a
multi-layer cover having an inner. Generally, golf ball cores
and/or centers are constructed with a thermoset rubber, typically a
polybutadiene-based composition. The cores are usually heated and
crosslinked to create certain characteristics, such as higher or
lower compression, which can impact the spin rate of the ball
and/or provide better "feel." These and other characteristics can
be tailored to the needs of golfers of different abilities. From
the perspective of a golf ball manufacturer, it is desirable to
have cores exhibiting a wide range of properties, such as
resilience, durability, spin, and "feel," because this enables the
manufacturer to make and sell many different types of golf balls
suited to differing levels of ability.
[0004] Heretofore, most single core golf ball cores have had a
conventional hard-to-soft hardness gradient from the surface of the
core to the center of the core, otherwise known as a "positive
hardness gradient." The patent literature contains a number of
references that discuss a hard surface to soft center hardness
gradient across a golf ball core.
[0005] U.S. Pat. No. 4,650,193 to Molitor et al. generally
discloses a hardness gradient in the surface layers of a core by
surface treating a slug of curable elastomer with a cure-altering
agent and subsequently molding the slug into a core. This treatment
allegedly creates a core with two zones of different compositions,
the first part being the hard, resilient, central portion of the
core, which was left untreated, and the second being the soft,
deformable, outer layer of the core, which was treated by the
cure-altering agent. The two "layers" or regions of the core are
integral with one another and, as a result, achieve the effect of a
gradient of soft surface to hard center.
[0006] U.S. Pat. No. 3,784,209 to Berman, et al. generally
discloses a soft-to-hard hardness gradient. The '209 patent
discloses a non-homogenous, molded golf ball with a core of "mixed"
elastomers. A center sphere of uncured elastomeric material is
surrounded by a compatible but different uncured elastomer. When
both layers of elastomer are concurrently exposed to a curing
agent, they become integral with one another, thereby forming a
mixed core. The center of this core, having a higher concentration
of the first elastomeric material, is harder than the outer layer.
One drawback to this method of manufacture is the time-consuming
process of creating first elastomer and then a second elastomer and
then molding the two together.
[0007] Other patents discuss cores that receive a surface treatment
to provide a soft `skin`. However, since the interior portions of
these cores are untreated, they have the similar hard surface to
soft center gradient as conventional cores. For example, U.S. Pat.
No. 6,113,831 to Nesbitt et al. generally discloses a conventional
core and a separate soft skin wrapped around the core. This soft
skin is created by exposing the preform slug to steam during the
molding process so that a maximum mold temperature exceeds a steam
set point, and by controlling exothermic molding temperatures
during molding. The skin comprises the radially-outermost 1/32 inch
to 1/4 inch of the spherical core. U.S. Pat. Nos. 5,976,443 and
5,733,206, both to Nesbitt et al., disclose the addition of water
mist to the outside surface of the slug before molding in order to
create a soft skin. The water allegedly softens the compression of
the core by retarding crosslinking on the core surface, thereby
creating an even softer soft skin around the hard central
portion.
[0008] Additionally, a number of patents disclose multilayer golf
ball cores, where each core layer has a different hardness thereby
creating a hardness gradient from core layer to core layer. There
remains a need, however, to achieve a multi-layer layer core that
has an inner layer having a "negative" hardness gradient and an
outer core layer having a steep "positive" hardness gradient. A
core exhibiting such characteristics would allow the golf ball
designer to create products with unique combinations of
compression, "feel," and spin.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a golf ball including
an inner core having a first outer surface and a geometric center
and being formed from a first substantially homogenous composition
throughout such that the geometric center has a hardness of 51 to
76 Shore C and the first outer surface has a hardness of 50 to 75
Shore C. An outer core layer is disposed about the inner core, the
outer core layer having a second outer surface having a hardness of
85 to 98 Shore C and an inner surface having a hardness of 68 to 78
Shore C and being formed from a second substantially homogenous
rubber composition throughout, the rubber composition comprising a
base rubber and a resorcinol. A cover layer is disposed about the
outer core layer. The hardness of the second outer surface is
preferably greater than the hardness of the inner surface to define
a positive hardness gradient of greater than 15 Shore C, more
preferably greater than 20 Shore C, most preferably greater than 25
Shore C. The hardness of the first outer surface is typically lower
than the hardness of the geometric center to define a negative
hardness gradient of -1 to -5 Shore C or, in an alternative
embodiment, between -6 Shore C and -15 Shore C, more preferably
between -8 and -12 Shore C.
[0010] The resorcinol is preferably present in an amount of about
0.1 pph to about 1.0 pph. In one embodiment, the hardness of the
first outer surface is 65 Shore C to 70 Shore C and the hardness of
the geometric center is 67 Shore C to 72 Shore C. Additionally, the
hardness of the second outer surface may be 90 Shore C to 95 Shore
C and the hardness of the inner surface may be 70 Shore C to 75
Shore C. In an preferred embodiment, the inner surface hardness is
less than the hardness of the geometric center and first outer
surface.
[0011] The first composition typically includes an antioxidant in
an amount of about 0.1 pph to about 1.0 pph. The cover layer can
include an inner cover layer and an outer cover layer. In an
alternative embodiment, the inner surface hardness is greater than
the hardness of the first outer surface and less than the hardness
of the geometric center.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a graph of the hardness of the core as a function
of the distance from its center for both inventive cores and
comparative example cores;
[0013] FIG. 2 is a graph depicting preferred hardness ranges for a
one embodiment of the present invention;
[0014] FIG. 3 is a graph depicting preferred hardness ranges for a
second embodiment of the present invention;
[0015] FIG. 4 is a graph depicting preferred hardness ranges for a
third embodiment of the present invention; and
[0016] FIG. 5 is a graph depicting preferred hardness ranges for a
fourth embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The golf balls of the present invention may include a
single-layer (one-piece) golf ball, and multi-layer golf balls,
such as one having a core and a cover surrounding the core, but are
preferably formed from a core comprised of a solid center
(otherwise known as an inner core) and an outer core layer, an
inner cover layer and an outer cover layer. Of course, any of the
core and/or the cover layers may include more than one layer. In a
preferred embodiment, the core is formed of an inner core and an
outer core layer, where the outer core layer has a steep "positive"
(conventional, i.e., the outer surface of the outer core layer is
harder than its inner surface) hardness gradient and the inner core
has a "soft-to-hard" hardness gradient (a "negative" hardness
gradient) radially inward from the outer surface towards the
innermost portion (i.e., the geometric center).
[0018] Alternative embodiments involving varying direction and
combination of hardness gradient amongst core components are also
envisioned (e.g., a "negative" gradient in the outer core layer
coupled with a "positive" gradient in the inner core).
[0019] The center of the core may also be a liquid-filled or hollow
sphere surrounded by one or more intermediate and/or cover layers,
or it may include a solid or liquid center around which tensioned
elastomeric material is wound. Any layers disposed around these
alternative centers may exhibit the inventive core hardness
gradient (i.e., "negative" or "positive"). The cover layer may be a
single layer or, for example, formed of a plurality of layers, such
as an inner cover layer and an outer cover layer.
[0020] As briefly discussed above, the inventive cores may have a
hardness gradient defined by hardness measurements made at the
surface of the inner core (or outer core layer) and radially inward
towards the center of the inner core, typically at 2-mm increments.
As used herein, the terms "negative" and "positive" refer to the
result of subtracting the hardness value at the innermost portion
of the component being measured (e.g., the center of a solid core
or an inner core in a dual core construction; the inner surface of
a core layer; etc.) from the hardness value at the outer surface of
the component being measured (e.g., the outer surface of a solid
core; the outer surface of an inner core in a dual core; the outer
surface of an outer core layer in a dual core, etc.). For example,
if the outer surface of a solid core has a lower hardness value
than the center (i.e., the surface is softer than the center), the
hardness gradient will be deemed a "negative" gradient (a smaller
number-a larger number=a negative number). It is preferred that the
inventive cores have an inner core having a "negative" hardness
gradient greater than (more negative) -1 Shore C, more preferably
between -1 and -5 Shore C or, alternatively, between -6 and -15
Shore C.
[0021] As discussed above, the direction of the hardness gradient
of a golf ball layer is defined by the difference in hardness
measurements taken at the outer and inner surfaces of a particular
layer. The center hardness of an inner core and the outer surfaces
of an inner core or outer core layer are readily determined
according to the procedures given herein. The outer surface of the
inner core layer (or other optional intermediate core layers) are
also readily determined according to the procedures given herein
for measuring the outer surface hardness of a golf ball layer, if
the measurement is made prior to surrounding the layer with an
additional core layer.
[0022] Once an additional core layer surrounds a layer of interest,
the hardness of the inner and outer surfaces of any inner or
intermediate layers can be difficult to determine. Therefore, for
purposes of the present invention, when the hardness of the inner
or outer surface of an outer core layer is needed after the inner
layer has been surrounded with another core layer, the procedure
below for measuring a point located 1 mm from an interface is
used.
[0023] The center hardness of a core is obtained according to the
following procedure. The core is gently pressed into a
hemispherical holder having an internal diameter approximately
slightly smaller than the diameter of the core, such that the core
is held in place in the hemispherical portion of the holder while
concurrently leaving the geometric central plane of the core
exposed. The core is secured in the holder by friction, such that
it will not move during the cutting and grinding steps, but the
friction is not so excessive that distortion of the natural shape
of the core would result. The core is secured such that the parting
line of the core is roughly parallel to the top of the holder. The
diameter of the core is measured 90 degrees to this orientation
prior to securing. A measurement is also made from the bottom of
the holder to the top of the core to provide a reference point for
future calculations. A rough cut is made slightly above the exposed
geometric center of the core using a band saw or other appropriate
cutting tool, making sure that the core does not move in the holder
during this step. The remainder of the core, still in the holder,
is secured to the base plate of a surface grinding machine. The
exposed `rough` surface is ground to a smooth, flat surface,
revealing the geometric center of the core, which can be verified
by measuring the height from the bottom of the holder to the
exposed surface of the core, making sure that exactly half of the
original height of the core, as measured above, has been removed to
within .+-.0.004 inches. Leaving the core in the holder, the center
of the core is found with a center square and carefully marked and
the hardness is measured at the center mark according to ASTM
D-2240. Additional hardness measurements at any distance from the
center of the core can then be made by drawing a line radially
outward from the center mark, and measuring the hardness at any
given distance along the line, typically in 2 mm increments from
the center. The hardness at a particular distance from the center
should be measured along at least two, preferably four, radial arms
located 180.degree. apart, or 90.degree. apart, respectively, and
then averaged. All hardness measurements performed on a plane
passing through the geometric center are performed while the core
is still in the holder and without having disturbed its
orientation, such that the test surface is constantly parallel to
the bottom of the holder, and thus also parallel to the properly
aligned foot of the durometer.
[0024] The outer surface hardness of a golf ball layer is measured
on the actual outer surface of the layer and is obtained from the
average of a number of measurements taken from opposing
hemispheres, taking care to avoid making measurements on the
parting line of the core or on surface defects, such as holes or
protrusions. Hardness measurements are made pursuant to ASTM D-2240
"Indentation Hardness of Rubber and Plastic by Means of a
Durometer." Because of the curved surface, care must be taken to
insure that the golf ball or golf ball subassembly is centered
under the durometer indentor before a surface hardness reading is
obtained. A calibrated, digital durometer, capable of reading to
0.1 hardness units is used for all hardness measurements and is set
to take hardness readings at 1 second after the maximum reading is
obtained. The digital durometer must be attached to, and its foot
made parallel to, the base of an automatic stand. The weight on the
durometer and attack rate conform to ASTM D-2240.
[0025] The hardness of a golf ball layer at a point located 1 mm
from an interface is obtained according to the following procedure.
First, an axis defining the geometric center of the core is
revealed by preparing the core according to the above procedure for
measuring the center hardness of a core. Leaving the core in the
holder, a point located 1 mm radially inward or outward from the
interface of two layers is determined and marked, and the hardness
thereof is measured according to ASTM D-2240.
[0026] Preferably the core layers (inner core or outer core layer)
is made from a composition including at least one thermoset base
rubber, such as a polybutadiene rubber, cured with at least one
peroxide and at least one reactive co-agent, which can be a metal
salt of an unsaturated carboxylic acid, such as acrylic acid or
methacrylic acid, a non-metallic coagent, or mixtures thereof.
Preferably, a suitable antioxidant is included in the composition.
An optional soft and fast agent (and sometimes a cis-to-trans
catalyst), such as an organosulfur or metal-containing organosulfur
compound, can also be included in the core formulation. Other
ingredients that are known to those skilled in the art may be used,
and are understood to include, but not be limited to,
density-adjusting fillers, process aides, plasticizers, blowing or
foaming agents, sulfur accelerators, and/or non-peroxide radical
sources.
[0027] The base thermoset rubber, which can be blended with other
rubbers and polymers, typically includes a natural or synthetic
rubber. A preferred base rubber is 1,4-polybutadiene having a cis
structure of at least 40%, preferably greater than 80%, and more
preferably greater than 90%.
[0028] Examples of desirable polybutadiene rubbers include
BUNA.RTM. CB22 and BUNA.RTM. CB23, commercially available from
LANXESS Corporation; UBEPOL.RTM. 360L and UBEPOL.RTM. 150L and
UBEPOL-BR rubbers, commercially available from UBE Industries, Ltd.
of Tokyo, Japan; KINEX.RTM. 7245 and KINEX.RTM. 7265, commercially
available from Goodyear of Akron, Ohio; SE BR-1220, and
TAKTENE.RTM. 1203G1, 220, and 221, commercially available from Dow
Chemical Company; EUROPRENE.RTM. NEOCIS.RTM. BR 40 and BR 60,
commercially available from Polimeri Europa; and BR 01, BR 730, BR
735, BR 11, and BR 51, commercially available from Japan Synthetic
Rubber Co., Ltd; PETROFLEX.RTM. BRNd-40; KARBOCHEM.RTM. ND40, ND45,
and ND60, commercially available from Karbochem; and SE BR-1220,
commercially available from The Dow Chemical Company.
[0029] Rubber compositions of the present invention include a
resorcinol, in particular the compositions used to form the steep
"positive" hardness gradient core layers, such as an outer core
layer. Preferred resorcinols include compounds represented by the
following formula, and hydrates thereof:
##STR00001##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4, is
independently selected from the group consisting of hydrogen, a
halogen group (F, Cl, Br, I), an alkyl group, a carboxyl group
(--COOH) and metal salts thereof (e.g., --COO.sup.-M.sup.+) and
esters thereof (-COOR), an acetate group (-CH.sub.2COOH) and esters
thereof (-CH.sub.2COOR), a formyl group (--CHO), an acyl group
(--COR), an acetyl group (-COCH.sub.3), a halogenated carbonyl
group (--COX), a sulfo group (--SO.sub.3H) and esters thereof
(--SO.sub.3R), a halogenated sulfonyl group (--SO.sub.2X), a
sulfino group (--SO.sub.2H), an alkylsulfinyl group (--SOR), a
carbamoyl group (--CONH.sub.2), a halogenated alkyl group, a cyano
group (--CN), an alkoxy group (--OR), a hydroxy group (--OH) and
metal salts thereof (e.g., --O.sup.-M.sup.+), an amino group
(--NH.sub.2), a nitro group (--NO.sub.2), an aryl group (e.g.,
phenyl, tolyl, etc.), an aryloxy group (e.g., phenoxy, etc.), an
arylalkyl group [e.g., cumyl (--C(CH.sub.3).sub.2phenyl); benzyl
(--CH.sub.2 phenyl)], a nitroso group (--NO), an acetamido group
(--NHCOCH.sub.3), and a vinyl group (--CH.dbd.CH.sub.2).
2-nitroresorcinol is particularly preferred.
[0030] Rubber compositions of the present invention may include a
combination of two or more resorcinols, each of which is
independently selected from compounds represented by the above
formula, or a combination of at least one resorcinol and one or
more chemical compounds selected from the group consisting of
hydroquinones, benzoquinones, quinhydrones, and catechols. Suitable
resorcinols and other additives may be found in co-pending U.S.
patent application Ser. Nos. 12/168,987 and 12/169,006, both filed
Jul. 8, 2008 and incorporated herein in their entirety by reference
thereto.
[0031] The present invention is not limited by a particular method
for adding the resorcinol to the rubber composition. The resorcinol
can be added as part of a masterbatch or in the neat form as a
liquid or solid.
[0032] The resorcinol is generally present in the rubber
composition in an amount of at least 0.05 parts by weight or at
least 0.1 parts by weight or at least 0.15 parts by weight or at
least 0.2 parts by weight per 100 parts of the base rubber, or an
amount within the range having a lower limit of 0.05 parts or 0.1
parts or 0.15 parts or 0.25 parts or 0.3 parts or 0.375 parts by
weight per 100 parts of the base rubber, and an upper limit of 0.5
parts or 1 part or 1.5 parts or 2 parts or 3 parts by weight per
100 parts of the base rubber. In a particular embodiment, a ratio
(P.sub.RESORCINOL/P.sub.INITIATOR) of the amount of the resorcinol
present in the rubber composition (P.sub.RESORCINOL) measured in
parts by weight per 100 parts of the base rubber, to the amount of
free radical initiator present in the rubber composition
(P.sub.INITIATOR), measured in parts by weight per 100 parts of the
base rubber, is from 0.05 to 2. In another embodiment,
P.sub.RESORCINOL/P.sub.INITIATOR is at least 0.05 and less than
0.5. In another embodiment, P.sub.RESORCINOL/P.sub.INITIATOR is at
least 0.2 and less than 0.5. In another embodiment,
P.sub.RESORCINOL/P.sub.INITIATOR is at least 0.25 and less than
0.5. In yet another embodiment, P.sub.RESORCINOL/P.sub.INITIATOR is
within the range having a lower limit of 0.05 or 0.2 or 0.25 and an
upper limit of 0.4 or 0.45 or 0.5 or 2.
[0033] The base rubber may also comprise high or medium Mooney
viscosity rubber, or blends thereof. A "Mooney" unit is a unit used
to measure the plasticity of raw or unvulcanized rubber. The
plasticity in a "Mooney" unit is equal to the torque, measured on
an arbitrary scale, on a disk in a vessel that contains rubber at a
temperature of 100.degree. C. and rotates at two revolutions per
minute. The measurement of Mooney viscosity is defined according to
ASTM D-1646. The Mooney viscosity range is preferably greater than
about 40, more preferably in the range from about 40 to about 80
and more preferably in the range from about 40 to about 60.
Polybutadiene rubber with higher Mooney viscosity may also be used,
so long as the viscosity of the polybutadiene does not reach a
level where the high viscosity polybutadiene clogs or otherwise
adversely interferes with the manufacturing machinery. It is
contemplated that polybutadiene with viscosity less than 65 Mooney
can be used with the present invention. In one embodiment of the
present invention, golf ball cores made with mid- to high-Mooney
viscosity polybutadiene material exhibit increased resiliency (and,
therefore, distance) without increasing the hardness of the ball.
Such cores are soft, i.e., compression less than about 60 and more
specifically in the range of about 50-55. Cores with compression in
the range of from about 30 about 50 are also within the range of
this preferred embodiment.
[0034] Commercial sources of suitable mid- to high-Mooney viscosity
polybutadiene include Bayer AG CB23 (Nd-catalyzed), which has a
Mooney viscosity of around 50 and is a highly linear polybutadiene,
and Shell 1220 (Co-catalyzed). If desired, the polybutadiene can
also be mixed with other elastomers known in the art, such as other
polybutadiene rubbers, natural rubber, styrene butadiene rubber,
and/or isoprene rubber in order to further modify the properties of
the core. When a mixture of elastomers is used, the amounts of
other constituents in the core composition are typically based on
100 parts by weight of the total elastomer mixture.
[0035] In one preferred embodiment, the base rubber comprises a
Nd-catalyzed polybutadiene, a rare earth-catalyzed polybutadiene
rubber, or blends thereof. If desired, the polybutadiene can also
be mixed with other elastomers known in the art such as natural
rubber, polyisoprene rubber and/or styrene-butadiene rubber in
order to modify the properties of the core. Other suitable base
rubbers include thermosetting materials such as, ethylene propylene
diene monomer rubber, ethylene propylene rubber, butyl rubber,
halobutyl rubber, hydrogenated nitrile butadiene rubber, nitrile
rubber, and silicone rubber.
[0036] Thermoplastic elastomers (TPE) many also be used to modify
the properties of the core layers, or the uncured core layer stock
by blending with the base thermoset rubber. These TPEs include
natural or synthetic balata, or high trans-polyisoprene, high
trans-polybutadiene, or any styrenic block copolymer, such as
styrene ethylene butadiene styrene, styrene-isoprene-styrene, etc.,
a metallocene or other single-site catalyzed polyolefin such as
ethylene-octene, or ethylene-butene, or thermoplastic polyurethanes
(TPU), including copolymers, e.g. with silicone. Other suitable
TPEs for blending with the thermoset rubbers of the present
invention 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. Any of the TPEs or TPUs above may also
contain functionality suitable for grafting, including maleic acid
or maleic anhydride.
[0037] Additional polymers may also optionally be incorporated into
the base rubber. Examples include, but are not limited to,
thermoset elastomers such as core regrind, thermoplastic
vulcanizate, copolymeric ionomer, terpolymeric ionomer,
polycarbonate, polyamide, copolymeric polyamide, polyesters,
polyvinyl alcohols, acrylonitrile-butadiene-styrene copolymers,
polyarylate, polyacrylate, polyphenylene ether, impact-modified
polyphenylene ether, high impact polystyrene, diallyl phthalate
polymer, styrene-acrylonitrile polymer (SAN) (including
olefin-modified SAN and acrylonitrile-styrene-acrylonitrile
polymer), styrene-maleic anhydride copolymer, styrenic copolymer,
functionalized styrenic copolymer, functionalized styrenic
terpolymer, styrenic terpolymer, cellulose polymer, liquid crystal
polymer, ethylene-vinyl acetate copolymers, polyurea, and
polysiloxane or any metallocene-catalyzed polymers of these
species.
[0038] Suitable polyamides for use as an additional polymeric
material in compositions within the scope of the present invention
also include resins obtained by: (1) polycondensation of (a) a
dicarboxylic acid, such as oxalic acid, adipic acid, sebacic acid,
terephthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic
acid, with (b) a diamine, such as ethylenediamine,
tetramethylenediamine, pentamethylenediamine, hexamethylenediamine,
or decamethylenediamine, 1,4-cyclohexanediamine, or
m-xylylenediamine; (2) a ring-opening polymerization of cyclic
lactam, such as .epsilon.-caprolactam or .OMEGA.-laurolactam; (3)
polycondensation of an aminocarboxylic acid, such as 6-aminocaproic
acid, 9-aminononanoic acid, 11-aminoundecanoic acid, or
12-aminododecanoic acid; or (4) copolymerization of a cyclic lactam
with a dicarboxylic acid and a diamine. Specific examples of
suitable polyamides include NYLON 6, NYLON 66, NYLON 610, NYLON 11,
NYLON 12, copolymerized NYLON, NYLON MXD6, and NYLON 46.
[0039] Suitable peroxide initiating agents include dicumyl
peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane;
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne;
2,5-dimethyl-2,5-di(benzoylperoxy)hexane;
2,2'-bis(t-butylperoxy)-di-iso-propylbenzene;
1,1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane; n-butyl
4,4-bis(t-butyl-peroxy)valerate; t-butyl perbenzoate; benzoyl
peroxide; n-butyl 4,4'-bis(butylperoxy)valerate; di-t-butyl
peroxide; or 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane, lauryl
peroxide, t-butyl hydroperoxide, .alpha.-.alpha.
bis(t-butylperoxy)diisopropylbenzene,
di(2-t-butyl-peroxyisopropyl)benzene, di-t-amyl peroxide,
di-t-butyl peroxide. Preferably, the rubber composition includes
from about 0.25 to about 5.0 parts by weight peroxide per 100 parts
by weight rubber (phr), more preferably 0.5 phr to 3 phr, most
preferably 0.5 phr to 1.5 phr. In a most preferred embodiment, the
peroxide is present in an amount of about 0.8 phr. These ranges of
peroxide are given assuming the peroxide is 100% active, without
accounting for any carrier that might be present. Because many
commercially available peroxides are sold along with a carrier
compound, the actual amount of active peroxide present must be
calculated. Commercially-available peroxide initiating agents
include DICUP.TM. family of dicumyl peroxides (including DICUP.TM.
R, DICUP.TM. 40C and DICUP.TM. 40KE) available from Crompton (Geo
Specialty Chemicals). Similar initiating agents are available from
AkroChem, Lanxess, Flexsys/Harwick and R. T. Vanderbilt. Another
commercially-available and preferred initiating agent is
TRIGONOX.TM. 265-50B from Akzo Nobel, which is a mixture of
1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane and
di(2-t-butylperoxyisopropyl)benzene. TRIGONOX.TM. peroxides are
generally sold on a carrier compound.
[0040] Suitable reactive co-agents include, but are not limited to,
metal salts of diacrylates, dimethacrylates, and monomethacrylates
suitable for use in this invention include those wherein the metal
is zinc, magnesium, calcium, barium, tin, aluminum, lithium,
sodium, potassium, iron, zirconium, and bismuth. Zinc diacrylate
(ZDA) is preferred, but the present invention is not limited
thereto. ZDA provides golf balls with a high initial velocity. The
ZDA can be of various grades of purity. For the purposes of this
invention, the lower the quantity of zinc stearate present in the
ZDA the higher the ZDA purity. ZDA containing less than about 10%
zinc stearate is preferable. More preferable is ZDA containing
about 4-8% zinc stearate. Suitable, commercially available zinc
diacrylates include those from Sartomer Co. The preferred
concentrations of ZDA that can be used are about 10 phr to about 40
phr, more preferably 20 phr to about 35 phr, most preferably 25 phr
to about 35 phr. In a particularly preferred embodiment, the
reactive co-agent is present in an amount of about 29 phr to about
31 phr.
[0041] Additional preferred co-agents that may be used alone or in
combination with those mentioned above include, but are not limited
to, trimethylolpropane trimethacrylate, trimethylolpropane
triacrylate, and the like. It is understood by those skilled in the
art, that in the case where these co-agents may be liquids at room
temperature, it may be advantageous to disperse these compounds on
a suitable carrier to promote ease of incorporation in the rubber
mixture.
[0042] Antioxidants are compounds that inhibit or prevent the
oxidative breakdown of elastomers, and/or inhibit or prevent
reactions that are promoted by oxygen radicals. Some exemplary
antioxidants that may be used in the present invention include, but
are not limited to, quinoline type antioxidants, amine type
antioxidants, and phenolic type antioxidants. A preferred
antioxidant is 2,2'-methylene-bis-(4-methyl-6-t-butylphenol)
available as VANOX.RTM. MBPC from R. T. Vanderbilt. Other
polyphenolic antioxidants include VANOX.RTM. T, VANOX.RTM. L,
VANOX.RTM. SKT, VANOX.RTM. SWP, VANOX.RTM. 13 and VANOX.RTM.
1290.
[0043] Suitable antioxidants include, but are not limited to,
alkylene-bis-alkyl substituted cresols, such as
4,4'-methylene-bis(2,5-xylenol);
4,4'-ethylidene-bis-(6-ethyl-m-cresol);
4,4'-butylidene-bis-(6-t-butyl-m-cresol);
4,4'-decylidene-bis-(6-methyl-m-cresol);
4,4'-methylene-bis-(2-amyl-m-cresol);
4,4'-propylidene-bis-(5-hexyl-m-cresol);
3,3'-decylidene-bis-(5-ethyl-p-cresol);
2,2'-butylidene-bis-(3-n-hexyl-p-cresol);
4,4'-(2-butylidene)-bis-(6-t-butyl-m-cresol);
3,3'-4(decylidene)-bis-(5-ethyl-p-cresol);
(2,5-dimethyl-4-hydroxyphenyl) (2-hydroxy-3,5-dimethylphenyl)
methane; (2-methyl-4-hydroxy-5-ethylphenyl)
(2-ethyl-3-hydroxy-5-methylphenyl) methane;
(3-methyl-5-hydroxy-6-t-butylphenyl)
(2-hydroxy-4-methyl-5-decylphenyl)-n-butyl methane;
(2-hydroxy-4-ethyl-5-methylphenyl)
(2-decyl-3-hydroxy-4-methylphenyl)butylamylmethane;
(3-ethyl-4-methyl-5-hydroxyphenyl)-(2,3-dimethyl-3-hydroxy-phenyl)nonylme-
thane;
(3-methyl-2-hydroxy-6-ethylphenyl)-(2-isopropyl-3-hydroxy-5-methyl--
phenyl)cyclohexylmethane; (2-methyl-4-hydroxy-5-methylphenyl)
(2-hydroxy-3-methyl-5-ethylphenyl)dicyclohexyl methane; and the
like.
[0044] Other suitable antioxidants include, but are not limited to,
substituted phenols, such as 2-tert-butyl-4-methoxyphenol;
3-tert-butyl-4-methoxyphenol; 3-tert-octyl-4-methoxyphenol;
2-methyl-4-methoxyphenol; 2-stearyl-4-n-butoxyphenol;
3-t-butyl-4-stearyloxyphenol; 3-lauryl-4-ethoxyphenol;
2,5-di-t-butyl-4-methoxyphenol; 2-methyl-4-methoxyphenol;
2-(1-methycyclohexyl)-4-methoxyphenol;
2-t-butyl-4-dodecyloxyphenol; 2-(1-methylbenzyl)-4-methoxyphenol;
2-t-octyl-4-methoxyphenol; methyl gallate; n-propyl gallate;
n-butyl gallate; lauryl gallate; myristyl gallate; stearyl gallate;
2,4,5-trihydroxyacetophenone; 2,4,5-trihydroxy-n-butyrophenone;
2,4,5-trihydroxystearophenone; 2,6-ditert-butyl-4-methylphenol;
2,6-ditert-octyl-4-methylphenol; 2,6-ditert-butyl-4-stearylphenol;
2-methyl-4-methyl-6-tert-butylphenol; 2,6-distearyl-4-methylphenol;
2,6-dilauryl-4-methylphenol; 2,6-di(n-octyl)-4-methylphenol;
2,6-di(n-hexadecyl)-4-methylphenol;
2,6-di(1-methylundecyl)-4-methylphenol;
2,6-di(1-methylheptadecyl)-4-methylphenol;
2,6-di(trimethylhexyl)-4-methylphenol;
2,6-di(1,1,3,3-tetramethyloctyl)-4-methylphenol; 2-n-dodecyl-6-tert
butyl-4-methylphenol;
2-n-dodecyl-6-(1-methylundecyl)-4-methylphenol;
2-n-dodecyl-6-(1,1,3,3-tetramethyloctyl)-4-methylphenol;
2-n-dodecyl-6-n-octadecyl-4-methylphenol;
2-n-dodecyl-6-n-octyl-4-methylphenol;
2-methyl-6-n-octadecyl-4-methylphenol;
2-n-dodecyl-6-(1-methylheptadecyl)-4-methylphenol;
2,6-di(1-methylbenzyl)-4-methylphenol;
2,6-di(1-methylcyclohexyl)-4-methylphenol;
2,6-(1-methylcyclohexyl)-4-methylphenol; and
2-(1-methylbenzyl)-4-methylphenol.
[0045] More suitable antioxidants include, but are not limited to,
alkylene bisphenols, such as 4,4'-butylidene bis(3-methyl-6-t-butyl
phenol); 2,2-butylidene bis(4,6-dimethyl phenol); 2,2'-butylidene
bis(4-methyl-6-t-butyl phenol); 2,2'-butylidene
bis(4-t-butyl-6-methyl phenol); 2,2'-ethylidene
bis(4-methyl-6-t-butylphenol); 2,2'-methylene bis(4,6-dimethyl
phenol); 2,2'-methylene bis(4-methyl-6-t-butyl phenol);
2,2'-methylene bis(4-ethyl-6-t-butyl phenol); 4,4'-methylene
bis(2,6-di-t-butyl phenol); 4,4'-methylene bis(2-methyl-6-t-butyl
phenol); 4,4'-methylene bis(2,6-dimethyl phenol); 2,2'-methylene
bis(4-t-butyl-6-phenyl phenol);
2,2'-dihydroxy-3,3',5,5'-tetramethylstilbene; 2,2'-isopropylidene
bis(4-methyl-6-t-butyl phenol); ethylene bis(beta-naphthol);
1,5-dihydroxy naphthalene; 2,2'-ethylene bis(4-methyl-6-propyl
phenol); 4,4'-methylene bis(2-propyl-6-t-butyl phenol);
4,4'-ethylene bis(2-methyl-6-propyl phenol); 2,2'-methylene
bis(5-methyl-6-t-butyl phenol); and 4,4'-butylidene
bis(6-t-butyl-3-methyl phenol).
[0046] Suitable antioxidants further include, but are not limited
to, alkylene trisphenols, such as
2,6-bis(2'-hydroxy-3'-t-butyl-5'-methyl benzyl)-4-methyl phenol;
2,6-bis(2'-hydroxy-3'-t-ethyl-5'-butyl benzyl)-4-methyl phenol; and
2,6-bis(2'-hydroxy-3'-t-butyl-5'-propyl benzyl)-4-methyl
phenol.
[0047] The antioxidant is typically present in an amount of about
0.1 phr to about 5 phr, preferably from about 0.1 phr to about 2
phr, more preferably about 0.1 phr to about 1 phr. In a
particularly preferred embodiment, the antioxidant is present in an
amount of about 0.4 phr. In an alternative embodiment, the
antioxidant should be present in an amount to ensure that the
hardness gradient of the inventive cores is negative. Preferably,
about 0.2 phr to about 1 phr antioxidant is added to the core layer
(inner core or outer core layer) formulation, more preferably,
about 0.3 to about 0.8 phr, and most preferably 0.4 to about 0.7
phr. Preferably, about 0.25 phr to about 1.5 phr of peroxide as
calculated at 100% active can be added to the core formulation,
more preferably about 0.5 phr to about 1.2 phr, and most preferably
about 0.7 phr to about 1.0 phr. The ZDA amount can be varied to
suit the desired compression, spin and feel of the resulting golf
ball. The cure regime can have a temperature range between from
about 290.degree. F. to about 335.degree. F., more preferably about
300.degree. F. to about 325.degree. F., and the stock is held at
that temperature for at least about 10 minutes to about 30
minutes.
[0048] The thermoset rubber composition of the present invention
may also include an optional soft and fast agent. As used herein,
"soft and fast agent" means any compound or a blend thereof that
that is capable of making a core 1) be softer (lower compression)
at constant COR or 2) have a higher COR at equal compression, or
any combination thereof, when compared to a core equivalently
prepared without a soft and fast agent. Preferably, the composition
of the present invention contains from about 0.05 phr to about 10.0
phr soft and fast agent. In one embodiment, the soft and fast agent
is present in an amount of about 0.05 phr to about 3.0 phr,
preferably about 0.05 phr to about 2.0 phr, more preferably about
0.05 phr to about 1.0 phr. In another embodiment, the soft and fast
agent is present in an amount of about 2.0 phr to about 5.0 phr,
preferably about 2.35 phr to about 4.0 phr, and more preferably
about 2.35 phr to about 3.0 phr. In an alternative high
concentration embodiment, the soft and fast agent is present in an
amount of about 5.0 phr to about 10.0 phr, more preferably about
6.0 phr to about 9.0 phr, most preferably about 7.0 phr to about
8.0 phr. In a most preferred embodiment, the soft and fast agent is
present in an amount of about 2.6 phr.
[0049] Suitable soft and fast agents include, but are not limited
to, organosulfur or metal-containing organosulfur compounds, an
organic sulfur compound, including mono, di, and polysulfides, a
thiol, or mercapto compound, an inorganic sulfide compound, a Group
VIA compound, or mixtures thereof. The soft and fast agent
component may also be a blend of an organosulfur compound and an
inorganic sulfide compound.
[0050] Suitable soft and fast agents of the present invention
include, but are not limited to those having the following general
formula:
##STR00002##
where R.sub.1-R.sub.5 can be C.sub.1-C.sub.8 alkyl groups; halogen
groups; thiol groups (--SH), carboxylated groups; sulfonated
groups; and hydrogen; in any order; and also pentafluorothiophenol;
2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol;
2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol;
3,5-fluorothiophenol 2,3,4-fluorothiophenol;
3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol;
2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol;
pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol;
4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol;
3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol;
3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol;
2,3,5,6-tetrachlorothiophenol; pentabromothiophenol;
2-bromothiophenol; 3-bromothiophenol; 4-bromothiophenol;
2,3-bromothiophenol; 2,4-bromothiophenol; 3,4-bromothiophenol;
3,5-bromothiophenol; 2,3,4-bromothiophenol; 3,4,5-bromothiophenol;
2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol;
pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol;
4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol;
3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol;
3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;
2,3,5,6-tetraiodothiophenoland; and their zinc salts. Preferably,
the halogenated thiophenol compound is pentachlorothiophenol, which
is commercially available in neat form or under the tradename
STRUKTOL.RTM., a clay-based carrier containing the sulfur compound
pentachlorothiophenol loaded at 45 percent (correlating to 2.4
parts PCTP). STRUKTOL.RTM. is commercially available from Struktol
Company of America of Stow, Ohio. PCTP is commercially available in
neat form from eChinachem of San Francisco, Calif. and in the salt
form from eChinachem of San Francisco, Calif. Most preferably, the
halogenated thiophenol compound is the zinc salt of
pentachlorothiophenol, which is commercially available from
eChinachem of San Francisco, Calif.
[0051] As used herein when referring to the invention, the term
"organosulfur compound(s)" refers to any compound containing
carbon, hydrogen, and sulfur, where the sulfur is directly bonded
to at least 1 carbon. As used herein, the term "sulfur compound"
means a compound that is elemental sulfur, polymeric sulfur, or a
combination thereof. It should be further understood that the term
"elemental sulfur" refers to the ring structure of S.sub.8 and that
"polymeric sulfur" is a structure including at least one additional
sulfur relative to elemental sulfur.
[0052] Additional suitable examples of soft and fast agents (that
are also believed to be cis-to-trans catalysts) include, but are
not limited to, 4,4'-diphenyl disulfide; 4,4'-ditolyl disulfide;
2,2'-benzamido diphenyl disulfide; bis(2-aminophenyl)disulfide;
bis(4-aminophenyl)disulfide; bis(3-aminophenyl)disulfide;
2,2'-bis(4-aminonaphthyl)disulfide;
2,2'-bis(3-aminonaphthyl)disulfide;
2,2'-bis(4-aminonaphthyl)disulfide;
2,2'-bis(5-aminonaphthyl)disulfide;
2,2'-bis(6-aminonaphthyl)disulfide;
2,2'-bis(7-aminonaphthyl)disulfide;
2,2'-bis(8-aminonaphthyl)disulfide;
1,1'-bis(2-aminonaphthyl)disulfide;
1,1'-bis(3-aminonaphthyl)disulfide;
1,1'-bis(3-aminonaphthyl)disulfide;
1,1'-bis(4-aminonaphthyl)disulfide;
1,1'-bis(5-aminonaphthyl)disulfide;
1,1'-bis(6-aminonaphthyl)disulfide;
1,1'-bis(7-aminonaphthyl)disulfide;
1,1'-bis(8-aminonaphthyl)disulfide;
1,2'-diamino-1,2'-dithiodinaphthalene;
2,3'-diamino-1,2'-dithiodinaphthalene;
bis(4-chlorophenyl)disulfide; bis(2-chlorophenyl)disulfide;
bis(3-chlorophenyl)disulfide; bis(4-bromophenyl)disulfide;
bis(2-bromophenyl)disulfide; bis(3-bromophenyl)disulfide;
bis(4-fluorophenyl)disulfide; bis(4-iodophenyl)disulfide;
bis(2,5-dichlorophenyl)disulfide; bis(3,5-dichlorophenyl)disulfide;
bis(2,4-dichlorophenyl)disulfide; bis(2,6-dichlorophenyl)disulfide;
bis(2,5-dibromophenyl)disulfide; bis(3,5-dibromophenyl)disulfide;
bis(2-chloro-5-bromophenyl)disulfide;
bis(2,4,6-trichlorophenyl)disulfide;
bis(2,3,4,5,6-pentachlorophenyl)disulfide;
bis(4-cyanophenyl)disulfide; bis(2-cyanophenyl)disulfide;
bis(4-nitrophenyl)disulfide; bis(2-nitrophenyl)disulfide;
2,2'-dithiobenzoic acid ethylester; 2,2'-dithiobenzoic acid
methylester; 2,2'-dithiobenzoic acid; 4,4'-dithiobenzoic acid
ethylester; bis(4-acetylphenyl)disulfide;
bis(2-acetylphenyl)disulfide; bis(4-formylphenyl) disulfide;
bis(4-carbamoylphenyl)disulfide; 1,1'-dinaphthyl disulfide;
2,2'-dinaphthyl disulfide; 1,2'-dinaphthyl disulfide;
2,2'-bis(1-chlorodinaphthyl)disulfide;
2,2'-bis(1-bromonaphthyl)disulfide;
1,1'-bis(2-chloronaphthyl)disulfide;
2,2'-bis(1-cyanonaphthyl)disulfide;
2,2'-bis(1-acetylnaphthyl)disulfide; and the like; or a mixture
thereof. Preferred organosulfur components include 4,4'-diphenyl
disulfide, 4,4'-ditolyl disulfide, or 2,2'-benzamido diphenyl
disulfide, or a mixture thereof. A more preferred organosulfur
component includes 4,4'-ditolyl disulfide. In another embodiment,
metal-containing organosulfur components can be used according to
the invention. Suitable metal-containing organosulfur components
include, but are not limited to, cadmium, copper, lead, and
tellurium analogs of diethyldithiocarbamate, diamyldithiocarbamate,
and dimethyldithiocarbamate, or mixtures thereof.
[0053] Suitable substituted or unsubstituted aromatic organic
components that do not include sulfur or a metal include, but are
not limited to, 4,4'-diphenyl acetylene, azobenzene, or a mixture
thereof. The aromatic organic group preferably ranges in size from
C.sub.6 to C.sub.20, and more preferably from C.sub.6 to C.sub.10.
Suitable inorganic sulfide components include, but are not limited
to titanium sulfide, manganese sulfide, and sulfide analogs of
iron, calcium, cobalt, molybdenum, tungsten, copper, selenium,
yttrium, zinc, tin, and bismuth.
[0054] A substituted or unsubstituted aromatic organic compound is
also suitable as a soft and fast agent. Suitable substituted or
unsubstituted aromatic organic components include, but are not
limited to, components having the formula
(R.sub.1).sub.x--R.sub.3-M-R.sub.4--(R.sub.2).sub.y, wherein
R.sub.1 and R.sub.2 are each hydrogen or a substituted or
unsubstituted C.sub.1-20 linear, branched, or cyclic alkyl, alkoxy,
or alkylthio group, or a single, multiple, or fused ring C.sub.6 to
C.sub.24 aromatic group; x and y are each an integer from 0 to 5;
R.sub.3 and R.sub.4 are each selected from a single, multiple, or
fused ring C.sub.6 to C.sub.24 aromatic group; and M includes an
azo group or a metal component. R.sub.3 and R.sub.4 are each
preferably selected from a C.sub.6 to C.sub.10 aromatic group, more
preferably selected from phenyl, benzyl, naphthyl, benzamido, and
benzothiazyl. R.sub.1 and R.sub.2 are each preferably selected from
a substituted or unsubstituted C.sub.1-10 linear, branched, or
cyclic alkyl, alkoxy, or alkylthio group or a C.sub.6 to C.sub.10
aromatic group. When R.sub.1, R.sub.2, R.sub.3, or R.sub.4 are
substituted, the substitution may include one or more of the
following substituent groups: hydroxy and metal salts thereof;
mercapto and metal salts thereof; halogen; amino, nitro, cyano, and
amido; carboxyl including esters, acids, and metal salts thereof;
silyl; acrylates and metal salts thereof; sulfonyl or sulfonamide;
and phosphates and phosphites. When M is a metal component, it may
be any suitable elemental metal available to those of ordinary
skill in the art. Typically, the metal will be a transition metal,
although preferably it is tellurium or selenium. In one embodiment,
the aromatic organic compound is substantially free of metal, while
in another embodiment the aromatic organic compound is completely
free of metal.
[0055] The soft and fast agent can also include a Group VIA
component. Elemental sulfur and polymeric sulfur are commercially
available from Elastochem, Inc. of Chardon, Ohio Exemplary sulfur
catalyst compounds include PB(RM-S)-80 elemental sulfur and
PB(CRST)-65 polymeric sulfur, each of which is available from
Elastochem, Inc. An exemplary tellurium catalyst under the
tradename TELLOY.RTM. and an exemplary selenium catalyst under the
tradename VANDEX.RTM. are each commercially available from RT
Vanderbilt.
[0056] Other suitable soft and fast agents include, but are not
limited to, hydroquinones, benzoquinones, quinhydrones, catechols,
and resorcinols.
[0057] Suitable hydroquinone compounds include compounds
represented by the following formula, and hydrates thereof:
##STR00003##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are hydrogen;
halogen; alkyl; carboxyl; metal salts thereof, and esters thereof;
acetate and esters thereof; formyl; acyl; acetyl; halogenated
carbonyl; sulfo and esters thereof; halogenated sulfonyl; sulfino;
alkylsulfinyl; carbamoyl; halogenated alkyl; cyano; alkoxy; hydroxy
and metal salts thereof; amino; nitro; aryl; aryloxy; arylalkyl;
nitroso; acetamido; or vinyl.
[0058] Other suitable hydroquinone compounds include, but are not
limited to, hydroquionone; tetrachlorohydroquinone;
2-chlorohydroquionone; 2-bromohydroquinone;
2,5-dichlorohydroquinone; 2,5-dibromohydroquinone;
tetrabromohydroquinone; 2-methylhydroquinone;
2-t-butylhydroquinone; 2,5-di-t-amylhydroquinone; and
2-(2-chlorophenyl) hydroquinone hydrate.
[0059] More suitable hydroquinone compounds include compounds
represented by the following formula, and hydrates thereof:
##STR00004##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are a metal
salt of a carboxyl; acetate and esters thereof; hydroxy; a metal
salt of a hydroxy; amino; nitro; aryl; aryloxy; arylalkyl; nitroso;
acetamido; or vinyl.
[0060] Suitable benzoquinone compounds include compounds
represented by the following formula, and hydrates thereof:
##STR00005##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are hydrogen;
halogen; alkyl; carboxyl; metal salts thereof, and esters thereof;
acetate and esters thereof; formyl; acyl; acetyl; halogenated
carbonyl; sulfo and esters thereof; halogenated sulfonyl; sulfino;
alkylsulfinyl; carbamoyl; halogenated alkyl; cyano; alkoxy; hydroxy
and metal salts thereof; amino; nitro; aryl; aryloxy; arylalkyl;
nitroso; acetamido; or vinyl.
[0061] Other suitable benzoquinone compounds include one or more
compounds represented by the following formula, and hydrates
thereof:
##STR00006##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are a metal
salt of a carboxyl; acetate and esters thereof; hydroxy; a metal
salt of a hydroxy; amino; nitro; aryl; aryloxy; arylalkyl; nitroso;
acetamido; or vinyl.
[0062] Suitable quinhydrones include one or more compounds
represented by the following formula, and hydrates thereof:
##STR00007##
wherein each R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, and R.sub.8 are hydrogen; halogen; alkyl; carboxyl; metal
salts thereof, and esters thereof; acetate and esters thereof;
formyl; acyl; acetyl; halogenated carbonyl; sulfo and esters
thereof; halogenated sulfonyl; sulfino; alkylsulfinyl; carbamoyl;
halogenated alkyl; cyano; alkoxy; hydroxy and metal salts thereof;
amino; nitro; aryl; aryloxy; arylalkyl; nitroso; acetamido; or
vinyl.
[0063] Other suitable quinhydrones include those having the above
formula, wherein each R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5,
R.sub.6, R.sub.7, and R.sub.8 are a metal salt of a carboxyl;
acetate and esters thereof; hydroxy; a metal salt of a hydroxy;
amino; nitro; aryl; aryloxy; arylalkyl; nitroso; acetamido; or
vinyl. Suitable catechols include one or more compounds represented
by the following formula, and hydrates thereof:
##STR00008##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are hydrogen;
halogen; alkyl; carboxyl; metal salts thereof, and esters thereof;
acetate and esters thereof; formyl; acyl; acetyl; halogenated
carbonyl; sulfo and esters thereof; halogenated sulfonyl; sulfino;
alkylsulfinyl; carbamoyl; halogenated alkyl; cyano; alkoxy; hydroxy
and metal salts thereof; amino; nitro; aryl; aryloxy; arylalkyl;
nitroso; acetamido; or vinyl.
[0064] Suitable resorcinols include one or more compounds
represented by the following formula, and hydrates thereof:
##STR00009##
wherein each R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are hydrogen;
halogen; alkyl; carboxyl; metal salts thereof, and esters thereof;
acetate and esters thereof; formyl; acyl; acetyl; halogenated
carbonyl; sulfo and esters thereof; halogenated sulfonyl; sulfino;
alkylsulfinyl; carbamoyl; halogenated alkyl; cyano; alkoxy; hydroxy
and metal salts thereof; amino; nitro; aryl; aryloxy; arylalkyl;
nitroso; acetamido; or vinyl.
[0065] Fillers may also be added to the thermoset rubber
composition of the core to adjust the density of the composition,
up or down. Typically, fillers include materials such as tungsten,
zinc oxide, barium sulfate, silica, calcium carbonate, zinc
carbonate, metals, metal oxides and salts, regrind (recycled core
material typically ground to about 30 mesh particle),
high-Mooney-viscosity rubber regrind, trans-regrind core material
(recycled core material containing high trans-isomer of
polybutadiene), and the like. When trans-regrind is present, the
amount of trans-isomer is preferably between about 10% and about
60%. In a preferred embodiment of the invention, the core comprises
polybutadiene having a cis-isomer content of greater than about 95%
and trans-regrind core material (already vulcanized) as a filler.
Any particle size trans-regrind core material is sufficient, but is
preferably less than about 125 .mu.m.
[0066] Fillers added to one or more portions of the golf ball
typically include processing aids or compounds to affect
rheological and mixing properties, density-modifying fillers, tear
strength, or reinforcement fillers, and the like. The fillers are
generally inorganic, and suitable fillers include numerous metals
or metal oxides, such as zinc oxide and tin oxide, as well as
barium sulfate, zinc sulfate, calcium carbonate, barium carbonate,
clay, tungsten, tungsten carbide, an array of silicas, and mixtures
thereof. Fillers may also include various foaming agents or blowing
agents which may be readily selected by one of ordinary skill in
the art. Fillers may include polymeric, ceramic, metal, and glass
microspheres may be solid or hollow, and filled or unfilled.
Fillers are typically also added to one or more portions of the
golf ball to modify the density thereof to conform to uniform golf
ball standards. Fillers may also be used to modify the weight of
the center or at least one additional layer for specialty balls,
e.g., a lower weight ball is preferred for a player having a low
swing speed.
[0067] Materials such as tungsten, zinc oxide, barium sulfate,
silica, calcium carbonate, zinc carbonate, metals, metal oxides and
salts, and regrind (recycled core material typically ground to
about 30 mesh particle) are also suitable fillers.
[0068] The polybutadiene and/or any other base rubber or elastomer
system may also be foamed, or filled with hollow microspheres or
with expandable microspheres which expand at a set temperature
during the curing process to any low specific gravity level. Other
ingredients such as sulfur accelerators, e.g., tetra methylthiuram
di, tri, or tetrasulfide, and/or metal-containing organosulfur
components may also be used according to the invention. Suitable
metal-containing organosulfur accelerators include, but are not
limited to, cadmium, copper, lead, and tellurium analogs of
diethyldithiocarbamate, diamyldithiocarbamate, and
dimethyldithiocarbamate, or mixtures thereof. Other ingredients
such as processing aids e.g., fatty acids and/or their metal salts,
processing oils, dyes and pigments, as well as other additives
known to one skilled in the art may also be used in the present
invention in amounts sufficient to achieve the purpose for which
they are typically used.
[0069] There are two preferred embodiments defined by the present
invention, which is preferably a golf ball including a "dual core,"
in which the inner core has a steep "positive" hardness gradient
and the outer core layer has a "negative" hardness gradient of
varying slope. The first embodiment is a golf ball having a dual
core where the inner core has a steep "positive" hardness gradient
of 20 Shore C or greater, more preferably 25 Shore C or greater,
most preferably 30 Shore C or greater, and the outer core layer has
a gradual "negative" gradient of -1 to -5 Shore C, more preferably
-2 to -5 Shore C, most preferably -2 to -4 Shore C. The second
embodiment is a golf ball having a dual core where the inner core
has a steep "positive" hardness gradient of 20 Shore C or greater,
more preferably 25 Shore C or greater, most preferably 30 Shore C
or greater, and the outer core layer has a steep "negative"
gradient of -6 or less (more negative, i.e., -7, -8, -9, -10,
etc.), preferably -6 to -15 Shore C, more preferably -8 to -12
Shore C, and most preferably about -10.
[0070] Representative graphs depicting the hardness regions in
which the steep "positive" and "negative" hardness gradients
disclosed herein can reside are shown in FIGS. 2 and 3. The
"negative" gradients, particularly in the above embodiments, can
have any slope (i.e., steep or shallow) whereas it is preferred
that the "positive" gradients, at least for the core layers, are
steep in nature (i.e., >20 Shore C).
[0071] Inner core compositions for both embodiments include at
least one base rubber, such as butadiene rubber (BR), ZDA, at least
one peroxide, optionally a metal salt of a halogenated thiophenol
(ZnPCTP), and a resorcinol, typically in an amount of 0.1 pph to
1.0 pph, more preferably 0.2 pph to 0.6 pph, and most preferably
0.3 pph to 0.5 pph. Outer core compositions also typically include
BR, ZDA, at least one peroxide, optionally a metal salt of a
halogenated thiophenol, and about 0.1 pph to 1 pph antioxidant
(AO), such as those listed herein. Adjusting AO levels allows
tailoring of the slope of the "negative" hardness gradient of the
outer core layer. No resorcinol is present when a "negative"
hardness gradient is desired.
[0072] Typical suitable compositions and properties are shown in
TABLE 1 below.
TABLE-US-00001 TABLE 1 Embodiment 1 Embodiment 2 Outer Core BR 100
100 trans-PI 0-15 0-15 ZDA 25-40 25-35 ZnO 5 5 Peroxide 0.5-2 0.5-2
AO 0.1-1 0.1-1 ZnPCTP 0-3 0-3 regrind 0-25 0-25 resorcinol 0 0
Filler Adjust weight as needed Adjust weight as needed Cure Temp
300-340.degree. F. 280-320.degree. F. Cure Time 10-30 min 10-30 min
Surface Hardness 50-75 Shore C 50-75 Shore C Inner Hardness 51-76
Shore C 56-80 Shore C Layer Gradient -1 to -5 -6 to -15 Inner Core
BR 100 100 ZDA 20-30 20-30 ZnO 5 5 Peroxide 0.5-2 0.5-2 AO 0 0
ZnPCTP 0-3 0-3 regrind 0-25 0-25 resorcinol 0.1-1 0.1-1 Filler
Adjust weight as needed Adjust weight as needed Cure Temp
340-400.degree. F. 340-400.degree. F. Cure Time 8-20 min 8-20 min
Surface Hardness 70-95 Shore C 70-95 Shore C Inner Hardness 40-60
Shore C 40-60 Shore C Layer Gradient +20-40 +20-40
[0073] In certain embodiments, a point or plurality of points
measured along the "positive" or "negative" gradients may be above
or below a line fit through the gradient and its outermost and
innermost hardness values. In an alternative preferred embodiment,
the hardest point along a particular steep "positive" or "negative"
gradient may be higher than the value at the innermost portion of
the inner core (the geometric center) or outer core layer (the
inner surface)--as long as the outermost point (i.e., the outer
surface of the inner core) is greater than (for "positive") or
lower than (for "negative") the innermost point (i.e., the
geometric center of the inner core or the inner surface of the
outer core layer), such that the "positive" and "negative"
gradients remain intact.
[0074] There are a number of suitable and alternative embodiments,
each of which provide a varying degree of golf ball performance
properties. In each of the following embodiments, the inner core
preferably has an outer diameter of about 1.00 inch and the core
(the combination of the inner core and the outer core layer)
preferably has an outer diameter of about 1.55 inches. Any cover
material listed herein would be suitable and an inner cover may or
may not be present. Preferably, an inner cover layer is present and
it an ionomer-based material, such as a highly-neutralized ionomer
or a blend of high-acid ionomers and FUSABOND.RTM.. Preferably the
outer cover is formed from a castable urethane or urea
material.
[0075] Alternative embodiments include a golf ball where the
hardness of the outer surface of the inner core generally ranges
from 70 Shore C to 95 Shore C, more preferably 85 Shore C to 95
Shore C, most preferably 90 Shore C to 95 Shore C, and the hardness
of the geometric center of the inner core generally ranges from 40
Shore C to 60 Shore C, more preferably 50 Shore C to 60 Shore C,
most preferably 55 Shore C to 60 Shore C, such that the "positive"
hardness gradient has a magnitude of greater than 20 Shore C.
[0076] Correspondingly, the hardness of the outer surface of the
outer core layer generally ranges from 50 Shore C to 75 Shore C,
more preferably 65 Shore C to 70 Shore C, and the hardness of the
inner surface of the outer core layer generally ranges from 51
Shore C to 76 Shore C, more preferably 67 Shore C to 72 Shore C
(for a shallow "negative" hardness gradient) and from 56 Shore C to
80 Shore C, more preferably 72 Shore C to 77 Shore C (for a steep
"negative" hardness gradient), such that the "negative hardness
gradient" has a magnitude of about -1 to -5 or -6 or less,
respectively.
[0077] There are two alternative preferred embodiments defined by
the present invention, which is preferably a golf ball including a
"dual core," in which the outer core layer has a steep "positive"
hardness gradient and the inner core has a "negative" hardness
gradient of varying slope. The third embodiment is a golf ball
having a dual core where the outer core layer has a steep
"positive" hardness gradient of 15 Shore C or greater, more
preferably 20 Shore C or greater, most preferably 25 Shore C or
greater, and the inner core has a gradual "negative" gradient of -1
to -5 Shore C, more preferably -2 to -5 Shore C, most preferably -2
to -4 Shore C. The fourth embodiment is a golf ball having a dual
core where the outer core layer has a steep "positive" hardness
gradient of 15 Shore C or greater, more preferably 20 Shore C or
greater, most preferably 25 Shore C or greater, and the inner core
has a steep "negative" gradient of -6 or less (more negative, i.e.,
-7, -8, -9, -10, etc.), preferably -6 to -15 Shore C, more
preferably -8 to -12 Shore C, and most preferably about -10.
[0078] Representative graphs depicting the hardness regions in
which the steep "positive" and "negative" hardness gradients
disclosed herein can reside are shown in FIGS. 4 and 5. The
"negative" gradients, particularly in the above embodiments, can
have any slope (i.e., steep or shallow) whereas it is preferred
that the "positive" gradients are steep in nature (i.e., >20
Shore C).
[0079] Outer core layer compositions for both embodiments include
at least one base rubber, such as butadiene rubber (BR), ZDA, at
least one peroxide, optionally a metal salt of a halogenated
thiophenol (ZnPCTP), and a resorcinol, typically in an amount of
0.1 pph to 1.0 pph, more preferably 0.2 pph to 0.6 pph, and most
preferably 0.3 pph to 0.5 pph. Inner core compositions typically
include BR, ZDA, at least one peroxide, optionally a metal salt of
a halogenated thiophenol, and about 0.1 pph to 1 pph antioxidant
(AO), such as those listed herein. Adjusting AO levels allows
tailoring of the slope of the "negative" hardness gradient of the
inner core. No resorcinol is present when a "negative" hardness
gradient is desired.
[0080] Typical suitable compositions and properties are shown in
TABLE 2 below.
TABLE-US-00002 TABLE 2 Embodiment 3 Embodiment 4 Outer Core BR 100
100 trans-PI 0-15 0-15 ZDA 30-50 30-50 ZnO 5 5 Peroxide 1-3 1-3 AO
0 0 ZnPCTP 0-3 0-3 regrind 0.25 0.25 resorcinol 0.1-1 0.1-1 Filler
Adjust weight as needed Adjust weight as needed Cure Temp
340-400.degree. F. 340-400.degree. F. Cure Time 8-20 min 8-20 min
Surface Hardness 85-98 Shore C 85-98 Shore C Inner Hardness 68-78
Shore C 68-78 Shore C Layer Gradient 15-25 15-25 Inner Core BR 100
100 ZDA 15-30 15-30 ZnO 5 5 Peroxide 0.5-2 0.5-2 AO 0.1-1 0.1-1
ZnPCTP 0-3 0-3 regrind 0-25 0-25 resorcinol 0 0 Filler Adjust
weight as needed Adjust weight as needed Cure Temp 300-340.degree.
F. 280-320.degree. F. Cure Time 8-25 min 8-25 min Surface Hardness
50-75 Shore C 50-75 Shore C Inner Hardness 51-76 Shore C 56-80
Shore C Layer Gradient -1 to -5 -6 to -15
[0081] There are a number of suitable and alternative embodiments,
each of which provide a varying degree of golf ball performance
properties. In each of the following embodiments, the inner core
preferably has an outer diameter of about 1.00 inch and the core
(the combination of the inner core and the outer core layer)
preferably has an outer diameter of about 1.55 inches. Any cover
material listed herein would be suitable and an inner cover may or
may not be present. Preferably, an inner cover layer is present and
it an ionomer-based material, such as a highly-neutralized ionomer
or a blend of high-acid ionomers and FUSABOND.RTM.. Preferably the
outer cover is formed from a castable urethane or urea
material.
[0082] Alternative embodiments include a golf ball where the
hardness of the outer surface of the outer core layer generally
ranges from 85 Shore C to 98 Shore C, more preferably 90 to 95
Shore C, and the hardness of the geometric center of the inner core
generally ranges from 68 Shore C to 78 Shore C, more preferably 70
to 75 Shore C, such that the "positive" hardness gradient has a
magnitude of greater than 15 Shore C, more preferably greater than
20 Shore C, most preferably greater than 25 Shore C.
[0083] Correspondingly, the hardness of the outer surface of the
inner core generally ranges from 50 Shore C to 75 Shore C, more
preferably 65 Shore C to 70 Shore C, and the hardness of the inner
surface of the inner core generally ranges from 51 Shore C to 76
Shore C, more preferably 67 Shore C to 72 Shore C (for a shallow
"negative" hardness gradient) and from 56 Shore C to 80 Shore C,
more preferably 72 Shore C to 77 Shore C (for a steep "negative"
hardness gradient), such that the "negative hardness gradient" has
a magnitude of about -1 to -5 or -6 or less, respectively.
[0084] The above embodiments may be tailored to meet predetermined
performance properties. For example, alternative embodiments
include those having an inner core having an outer diameter of
about 0.250 inches to about 1.550 inches, preferably about 0.500
inches to about 1.500 inches, and more preferably about 0.750
inches to about 1.400 inches. In preferred embodiments, the inner
core has an outer diameter of about 1.000 inch, 1.200 inches, or
1.300 inches, with a most preferred outer diameter being 1.130
inches. The outer core layer should have an outer diameter (the
entire dual core) of about 1.30 inches to about 1.620 inches,
preferably 1.400 inches to about 1.600 inches, and more preferably
about 1.500 inches to about 1.590 inches. In preferred embodiments,
the outer core layer has an outer diameter of about 1.510 inches,
1.530 inches, or most preferably 1.550 inches.
[0085] A number of cores were formed based on the formulation and
cure cycle described in TABLE 3 below and core hardness values are
reported in TABLE 4 below and plotted in FIG. 1.
TABLE-US-00003 TABLE 3 Ex 1 Ex 2 Ex 3 Comp Ex 1 Comp Ex 2 Comp Ex 3
Formulation (phr) SR-526.sup.+ 34.0 34.0 31.2 29.0 29.0 29.0 ZnO 5
5 5 5 5 5 BaSO.sub.4 11.2 11.2 16.1 13.8 13.8 13.8 VANOX MBPC* 0.40
0.40 0.40 -- 0.50 -- TRIGONOX-265- 1.4 1.4 1.6 -- -- 0.8 50B**
PERKADOX BC- -- -- -- 1.0 1.6 -- FF*** polybutadiene 100 100 100
100 100 100 ZnPCTP 2.35 2.35 2.60 2.35 2.35 2.35 regrind -- -- 17
17 -- -- antioxidant/initiator 0.57 0.57 0.50 -- 0.31 -- ratio Cure
Temp. (.degree. F.) 305 315 320 350 335 335 Cure Time (min) 14 11
16 11 11 11 Properties diameter (in) 1.530 1.530 1.530 1.530 1.530
1.530 Atti compression 69 63 70 69 47 -- COR @ 125 ft/s 0.808 0.806
0.804 0.804 -- -- *Vanox MBPC is
2,2'-methylene-bis-(4-methyl-6-t-butylphenol), available from R.T.
Vanderbilt Company, Inc.; **Trigonox 265-50B is a mixture of
1,1-di(t-butylperoxy)-3,3,5-trimethycyclohexane and
di(2-t-butylperoxyisopropyl)benzene, 50% active on an inert
carrier, available from Akzo Nobel; ***Perkadox BC-FF is dicumyl
peroxide (99%-100% active), available from Akzo Nobel; and
.sup.+SR-526 is ZDA, available from Sartomer.
TABLE-US-00004 TABLE 4 Shore C Hardness Distance from Comp Comp
Center Ex 1 Ex 2 Ex 3 Comp Ex 1 Ex 2 Ex 3 Center 73 70 71 61 52 61
2 74 71 72 67 57 62 4 74 72 73 70 62 65 6 75 73 73 72 64 67 8 75 73
73 73 64 69 10 75 73 74 73 64 71 12 74 74 73 72 66 72 14 74 74 72
73 70 73 16 70 71 70 77 71 73 18 60 60 63 80 72 73 Surface 63 70 66
85 73 74 Surface - Center -10 0 -5 24 21 13
[0086] Referring to TABLES 3-4, in Example 1, the surface is 10
Shore C points lower than the center hardness and 12 Shore C points
lower than the hardest point in the core. In Example 3, the surface
is 5 Shore C points lower than the center hardness and 8 Shore C
points lower than the hardest point in the core. In Example 2, the
center and surface hardness values are equal and the softest point
in the core is 10 Shore C points lower than the surface.
[0087] In the examples of the invention presented in TABLE 3, the
cure temperatures are varied from 305.degree. F. to 320.degree. F.
and cure times are varied from 11 to 16 minutes. The core
compositions of examples 1 and 2 are identical, and only the cure
cycle is changed. In example 3 the amount of antioxidant is
identical to examples 1 and 2, but other ingredients are varied as
well the cure cycle. Additionally, the ratio of antioxidant to
initiator varies from 0.50 to 0.57 from example 1 and 2 to example
3.
[0088] The ratio of antioxidant to initiator is one factor to
control the surface hardness of the cores. The data shown in TABLE
4 shows that hardness gradient is at least, but not limited to, a
function of the amount of antioxidant and peroxide, their ratio,
and the cure cycle. It should be noted that higher antioxidant also
requires higher peroxide initiator to maintain the desired
compression.
[0089] In FIG. 1, cores of Comparative Examples 1-3 are compared to
the inventive cores. The core of Comparative Example 1, whose
composition is shown in TABLE 3 was cured using a conventional cure
cycle, with a cure temperature of 350.degree. F. and a cure time of
11 minutes. The inventive cores were produced using cure cycles of
305.degree. F. for 14 minutes, 315.degree. F. for 11 minutes and
320.degree. F. for 16 minutes. The hardness gradients of these
cores were measured and the following observations can be made. For
the cores of the Comparative Examples, as expected, a conventional
hard surface to soft center gradient can be clearly seen. The
gradients for inventive cores follow substantially the same shape
as one another.
[0090] In all preferred embodiments of invention, the hardness of
the core at the surface is at most about the same as or
substantially less than the hardness of the core at the center.
Furthermore, the center hardness of the core may not be the hardest
point in the core, but in all cases, it is preferred that it is at
least equal to or harder than the surface. Additionally, the lowest
hardness anywhere in the core does not have to occur at the
surface. In some embodiments, the lowest hardness value occurs
within about the outer 6 mm of the core surface. However, the
lowest hardness value within the core can occur at any point from
the surface, up to, but not including the center, as long as the
surface hardness is still equal to, or less than the hardness of
the center. It should be noted that in the present invention the
formulation is the same throughout the core, or core layer, and no
surface treatment is applied to the core to obtain the preferred
surface hardness.
[0091] While the inventive golf ball may be formed from a variety
of differing and conventional cover materials (both intermediate
layer(s) and outer cover layer), preferred cover materials include,
but are not limited to: [0092] (1) Polyurethanes, such as those
prepared from polyols or polyamines and diisocyanates or
polyisocyanates and/or their prepolymers, and those disclosed in
U.S. Pat. Nos. 5,334,673 and 6,506,851; [0093] (2) Polyureas, such
as those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794; and
[0094] (3) Polyurethane-urea hybrids, blends or copolymers
comprising urethane or urea segments.
[0095] Suitable polyurethane compositions comprise a reaction
product of at least one polyisocyanate and at least one curing
agent. The curing agent can include, for example, one or more
polyamines, one or more polyols, or a combination thereof. The
polyisocyanate can be combined with one or more polyols to form a
prepolymer, which is then combined with the at least one curing
agent. Thus, the polyols described herein are suitable for use in
one or both components of the polyurethane material, i.e., as part
of a prepolymer and in the curing agent. Suitable polyurethanes are
described in U.S. Pat. No. 7,331,878, which is incorporated herein
in its entirety by reference.
[0096] Any polyisocyanate available to one of ordinary skill in the
art is suitable for use according to the invention. Exemplary
polyisocyanates include, but are not limited to,
4,4'-diphenylmethane diisocyanate (MDI); polymeric MDI;
carbodiimide-modified liquid MDI; 4,4'-dicyclohexylmethane
diisocyanate (H.sub.12MDI); p-phenylene diisocyanate (PPDI);
m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI);
3,3'-dimethyl-4,4'-biphenylene diisocyanate;
isophoronediisocyanate; 1,6-hexamethylene diisocyanate (HDI);
naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene
diisocyanate; m-tetramethylxylene diisocyanate; ethylene
diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl
cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of
2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate;
napthalene diisocyanate; anthracene diisocyanate; isocyanurate of
toluene diisocyanate; uretdione of hexamethylene diisocyanate; and
mixtures thereof. Polyisocyanates are known to those of ordinary
skill in the art as having more than one isocyanate group, e.g.,
di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably,
the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof,
and more preferably, the polyisocyanate includes MDI. It should be
understood that, as used herein, the term MDI includes
4,4'-diphenylmethane diisocyanate, polymeric MDI,
carbodiimide-modified liquid MDI, and mixtures thereof and,
additionally, that the diisocyanate employed may be "low free
monomer," understood by one of ordinary skill in the art to have
lower levels of "free" monomer isocyanate groups, typically less
than about 0.1% free monomer isocyanate groups. Examples of "low
free monomer" diisocyanates include, but are not limited to Low
Free Monomer MDI, Low Free Monomer TDI, and Low Free Monomer
PPDI.
[0097] The at least one polyisocyanate should have less than about
14% unreacted NCO groups. Preferably, the at least one
polyisocyanate has no greater than about 8.0% NCO, more preferably
no greater than about 7.8%, and most preferably no greater than
about 7.5% NCO with a level of NCO of about 7.2 or 7.0, or 6.5% NCO
commonly used.
[0098] Any polyol available to one of ordinary skill in the art is
suitable for use according to the invention. Exemplary polyols
include, but are not limited to, polyether polyols,
hydroxy-terminated polybutadiene (including partially/fully
hydrogenated derivatives), polyester polyols, polycaprolactone
polyols, and polycarbonate polyols. In one preferred embodiment,
the polyol includes polyether polyol. Examples include, but are not
limited to, polytetramethylene ether glycol (PTMEG), polyethylene
propylene glycol, polyoxypropylene glycol, and mixtures thereof.
The hydrocarbon chain can have saturated or unsaturated bonds and
substituted or unsubstituted aromatic and cyclic groups.
Preferably, the polyol of the present invention includes PTMEG.
[0099] In another embodiment, polyester polyols are included in the
polyurethane material. Suitable polyester polyols include, but are
not limited to, polyethylene adipate glycol; polybutylene adipate
glycol; polyethylene propylene adipate glycol;
o-phthalate-1,6-hexanediol; poly(hexamethylene adipate) glycol; and
mixtures thereof. The hydrocarbon chain can have saturated or
unsaturated bonds, or substituted or unsubstituted aromatic and
cyclic groups.
[0100] In another embodiment, polycaprolactone polyols are included
in the materials of the invention. Suitable polycaprolactone
polyols include, but are not limited to, 1,6-hexanediol-initiated
polycaprolactone, diethylene glycol initiated polycaprolactone,
trimethylol propane initiated polycaprolactone, neopentyl glycol
initiated polycaprolactone, 1,4-butanediol-initiated
polycaprolactone, and mixtures thereof. The hydrocarbon chain can
have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups.
[0101] In yet another embodiment, polycarbonate polyols are
included in the polyurethane material of the invention. Suitable
polycarbonates include, but are not limited to, polyphthalate
carbonate and poly(hexamethylene carbonate) glycol. The hydrocarbon
chain can have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups. In one embodiment, the
molecular weight of the polyol is from about 200 to about 4000.
[0102] Polyamine curatives are also suitable for use in the
polyurethane composition of the invention and have been found to
improve cut, shear, and impact resistance of the resultant balls.
Preferred polyamine curatives include, but are not limited to,
3,5-dimethylthio-2,4-toluenediamine and isomers thereof;
3,5-diethyltoluene-2,4-diamine and isomers thereof, such as
3,5-diethyltoluene-2,6-diamine;
4,4'-bis-(sec-butylamino)-diphenylmethane;
1,4-bis-(sec-butylamino)-benzene,
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(3-chloro-2,6-diethylaniline);
polytetramethyleneoxide-di-p-aminobenzoate; N,N'-dialkyldiamino
diphenyl methane; p,p'-methylene dianiline; m-phenylenediamine;
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(2,6-diethylaniline);
4,4'-methylene-bis-(2,3-dichloroaniline);
4,4'-diamino-3,3'-diethyl-5,5'-dimethyl diphenylmethane;
2,2',3,3'-tetrachloro diamino diphenylmethane; trimethylene glycol
di-p-aminobenzoate; and mixtures thereof. Preferably, the curing
agent of the present invention includes
3,5-dimethylthio-2,4-toluenediamine and isomers thereof, such as
ETHACURE.RTM. 300, commercially available from Albermarle
Corporation of Baton Rouge, La. Suitable polyamine curatives, which
include both primary and secondary amines, preferably have
molecular weights ranging from about 64 to about 2000.
[0103] At least one of a diol, triol, tetraol, or
hydroxy-terminated curatives may be added to the aforementioned
polyurethane composition. Suitable diol, triol, and tetraol groups
include ethylene glycol; diethylene glycol; polyethylene glycol;
propylene glycol; polypropylene glycol; lower molecular weight
polytetramethylene ether glycol; 1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;
1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;
1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;
resorcinol-di-(.beta.-hydroxyethyl)ether;
hydroquinone-di-(.beta.-hydroxyethyl)ether; and mixtures thereof.
Preferred hydroxy-terminated curatives include
1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;
1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;
1,4-butanediol, and mixtures thereof. Preferably, the
hydroxy-terminated curatives have molecular weights ranging from
about 48 to 2000. It should be understood that molecular weight, as
used herein, is the absolute weight average molecular weight and
would be understood as such by one of ordinary skill in the
art.
[0104] Both the hydroxy-terminated and amine curatives can include
one or more saturated, unsaturated, aromatic, and cyclic groups.
Additionally, the hydroxy-terminated and amine curatives can
include one or more halogen groups. The polyurethane composition
can be formed with a blend or mixture of curing agents. If desired,
however, the polyurethane composition may be formed with a single
curing agent.
[0105] In a preferred embodiment of the present invention,
saturated polyurethanes are used to form one or more of the cover
layers, preferably the outer cover layer, and may be selected from
among both castable thermoset and thermoplastic polyurethanes. In
this embodiment, the saturated polyurethanes of the present
invention are substantially free of aromatic groups or moieties.
Saturated polyurethanes suitable for use in the invention are a
product of a reaction between at least one polyurethane prepolymer
and at least one saturated curing agent. The polyurethane
prepolymer is a product formed by a reaction between at least one
saturated polyol and at least one saturated diisocyanate. As is
well known in the art, that a catalyst may be employed to promote
the reaction between the curing agent and the isocyanate and
polyol, or the curing agent and the prepolymer.
[0106] Saturated diisocyanates which can be used include, without
limitation, ethylene diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate
(HDI); 2,2,4-trimethylhexamethylene diisocyanate;
2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; dicyclohexylmethane diisocyanate;
cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isophorone diisocyanate; methyl cyclohexylene diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate. The most preferred saturated diisocyanates are
4,4'-dicyclohexylmethane diisocyanate and isophorone
diisocyanate.
[0107] Saturated polyols which are appropriate for use in this
invention include without limitation polyether polyols such as
polytetramethylene ether glycol and poly(oxypropylene) glycol.
Suitable saturated polyester polyols include polyethylene adipate
glycol, polyethylene propylene adipate glycol, polybutylene adipate
glycol, polycarbonate polyol and ethylene oxide-capped
polyoxypropylene diols. Saturated polycaprolactone polyols which
are useful in the invention include diethylene glycol-initiated
polycaprolactone, 1,4-butanediol-initiated polycaprolactone,
1,6-hexanediol-initiated polycaprolactone; trimethylol
propane-initiated polycaprolactone, neopentyl glycol initiated
polycaprolactone, and polytetramethylene ether glycol-initiated
polycaprolactone. The most preferred saturated polyols are
polytetramethylene ether glycol and PTMEG-initiated
polycaprolactone.
[0108] Suitable saturated curatives include 1,4-butanediol,
ethylene glycol, diethylene glycol, polytetramethylene ether
glycol, propylene glycol; trimethanolpropane;
tetra-(2-hydroxypropyl)-ethylenediamine; isomers and mixtures of
isomers of cyclohexyldimethylol, isomers and mixtures of isomers of
cyclohexane bis(methylamine); triisopropanolamine; ethylene
diamine; diethylene triamine; triethylene tetramine; tetraethylene
pentamine; 4,4'-dicyclohexylmethane diamine;
2,2,4-trimethyl-1,6-hexanediamine;
2,4,4-trimethyl-1,6-hexanediamine; diethyleneglycol
di-(aminopropyl)ether;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,2-bis-(sec-butylamino)cyclohexane;
1,4-bis-(sec-butylamino)cyclohexane; isophorone diamine;
hexamethylene diamine; propylene diamine; 1-methyl-2,4-cyclohexyl
diamine; 1-methyl-2,6-cyclohexyl diamine; 1,3-diaminopropane;
dimethylamino propylamine; diethylamino propylamine;
imido-bis-propylamine; isomers and mixtures of isomers of
diaminocyclohexane; monoethanolamine; diethanolamine;
triethanolamine; monoisopropanolamine; and diisopropanolamine. The
most preferred saturated curatives are 1,4-butanediol,
1,4-cyclohexyldimethylol and
4,4'-bis-(sec-butylamino)-dicyclohexylmethane.
[0109] Alternatively, other suitable polymers include partially or
fully neutralized ionomer, metallocene, or other single-site
catalyzed polymer, polyester, polyamide, non-ionomeric
thermoplastic elastomer, copolyether-esters, copolyether-amides,
polycarbonate, polybutadiene, polyisoprene, polystryrene block
copolymers (such as styrene-butadiene-styrene),
styrene-ethylene-propylene-styrene,
styrene-ethylene-butylene-styrene, and the like, and blends
thereof. Thermosetting polyurethanes or polyureas are suitable for
the outer cover layers of the golf balls of the present
invention.
[0110] Additionally, polyurethane can be replaced with or blended
with a polyurea material. Polyureas are distinctly different from
polyurethane compositions, but also result in desirable aerodynamic
and aesthetic characteristics when used in golf ball components.
The polyurea-based compositions are preferably saturated in
nature.
[0111] Without being bound to any particular theory, it is now
believed that substitution of the long chain polyol segment in the
polyurethane prepolymer with a long chain polyamine oligomer soft
segment to form a polyurea prepolymer, improves shear, cut, and
resiliency, as well as adhesion to other components. Thus, the
polyurea compositions of this invention may be formed from the
reaction product of an isocyanate and polyamine prepolymer
crosslinked with a curing agent. For example, polyurea-based
compositions of the invention may be prepared from at least one
isocyanate, at least one polyether amine, and at least one diol
curing agent or at least one diamine curing agent.
[0112] Any polyamine available to one of ordinary skill in the art
is suitable for use in the polyurea prepolymer. Polyether amines
are particularly suitable for use in the prepolymer. As used
herein, "polyether amines" refer to at least polyoxyalkyleneamines
containing primary amino groups attached to the terminus of a
polyether backbone. Due to the rapid reaction of isocyanate and
amine, and the insolubility of many urea products, however, the
selection of diamines and polyether amines is limited to those
allowing the successful formation of the polyurea prepolymers. In
one embodiment, the polyether backbone is based on tetramethylene,
propylene, ethylene, trimethylolpropane, glycerin, and mixtures
thereof.
Suitable polyether amines include, but are not limited to,
methyldiethanolamine; polyoxyalkylenediamines such as,
polytetramethylene ether diamines, polyoxypropylenetriamine, and
polyoxypropylene diamines; poly(ethylene oxide capped
oxypropylene)ether diamines; propylene oxide-based triamines;
triethyleneglycoldiamines; trimethylolpropane-based triamines;
glycerin-based triamines; and mixtures thereof. In one embodiment,
the polyether amine used to form the prepolymer is JEFFAMINE.RTM.
D2000 (manufactured by Huntsman Chemical Co. of Austin, Tex.).
[0113] The molecular weight of the polyether amine for use in the
polyurea prepolymer may range from about 100 to about 5000. In one
embodiment, the polyether amine molecular weight is about 200 or
greater, preferably about 230 or greater. In another embodiment,
the molecular weight of the polyether amine is about 4000 or less.
In yet another embodiment, the molecular weight of the polyether
amine is about 600 or greater. In still another embodiment, the
molecular weight of the polyether amine is about 3000 or less. In
yet another embodiment, the molecular weight of the polyether amine
is between about 1000 and about 3000, and more preferably is
between about 1500 to about 2500. Because lower molecular weight
polyether amines may be prone to forming solid polyureas, a higher
molecular weight oligomer, such as JEFFAMINE.RTM. D2000, is
preferred.
[0114] As briefly discussed above, some amines may be unsuitable
for reaction with the isocyanate because of the rapid reaction
between the two components. In particular, shorter chain amines are
fast reacting. In one embodiment, however, a hindered secondary
diamine may be suitable for use in the prepolymer. Without being
bound to any particular theory, it is believed that an amine with a
high level of stearic hindrance, e.g., a tertiary butyl group on
the nitrogen atom, has a slower reaction rate than an amine with no
hindrance or a low level of hindrance. For example,
4,4'-bis-(sec-butylamino)-dicyclohexylmethane (CLEARLINK.RTM. 1000)
may be suitable for use in combination with an isocyanate to form
the polyurea prepolymer.
[0115] Any isocyanate available to one of ordinary skill in the art
is suitable for use in the polyurea prepolymer. Isocyanates for use
with the present invention include aliphatic, cycloaliphatic,
araliphatic, aromatic, any derivatives thereof, and combinations of
these compounds having two or more isocyanate (NCO) groups per
molecule. The isocyanates may be organic polyisocyanate-terminated
prepolymers. The isocyanate-containing reactable component may also
include any isocyanate-functional monomer, dimer, trimer, or
multimeric adduct thereof, prepolymer, quasi-prepolymer, or
mixtures thereof. Isocyanate-functional compounds may include
monoisocyanates or polyisocyanates that include any isocyanate
functionality of two or more.
[0116] Suitable isocyanate-containing components include
diisocyanates having the generic structure:
O.dbd.C.dbd.N--R--N.dbd.C.dbd.O, where R is preferably a cyclic,
aromatic, or linear or branched hydrocarbon moiety containing from
about 1 to about 20 carbon atoms. The diisocyanate may also contain
one or more cyclic groups or one or more phenyl groups. When
multiple cyclic or aromatic groups are present, linear and/or
branched hydrocarbons containing from about 1 to about 10 carbon
atoms can be present as spacers between the cyclic or aromatic
groups. In some cases, the cyclic or aromatic group(s) may be
substituted at the 2-, 3-, and/or 4-positions, or at the ortho-,
meta-, and/or para-positions, respectively. Substituted groups may
include, but are not limited to, halogens, primary, secondary, or
tertiary hydrocarbon groups, or a mixture thereof.
[0117] Examples of diisocyanates that can be used with the present
invention include, but are not limited to, substituted and isomeric
mixtures including 2,2'-, 2,4'-, and 4,4'-diphenylmethane
diisocyanate; 3,3'-dimethyl-4,4'-biphenylene diisocyanate; toluene
diisocyanate; polymeric MDI; carbodiimide-modified liquid
4,4'-diphenylmethane diisocyanate; para-phenylene diisocyanate;
meta-phenylene diisocyanate; triphenyl methane-4,4'- and triphenyl
methane-4,4'-triisocyanate; naphthylene-1,5-diisocyanate; 2,4'-,
4,4'-, and 2,2-biphenyl diisocyanate; polyphenyl polymethylene
polyisocyanate; mixtures of MDI and PMDI; mixtures of PMDI and TDI;
ethylene diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,2-diisocyanate; tetramethylene-1,3-diisocyanate;
tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate;
octamethylene diisocyanate; decamethylene diisocyanate;
2,2,4-trimethylhexamethylene diisocyanate;
2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate;
2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane
diisocyanate; 4,4'-dicyclohexyl diisocyanate; 2,4'-dicyclohexyl
diisocyanate; 1,3,5-cyclohexane triisocyanate;
isocyanatomethylcyclohexane isocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isocyanatoethylcyclohexane isocyanate;
bis(isocyanatomethyl)-cyclohexane diisocyanate;
4,4'-bis(isocyanatomethyl)dicyclohexane;
2,4'-bis(isocyanatomethyl)dicyclohexane; isophorone diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate; 4,4'-dicyclohexylmethane diisocyanate;
2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene
diisocyanate; 1,2-, 1,3-, and 1,4-phenylene diisocyanate; aromatic
aliphatic isocyanate, such as 1,2-, 1,3-, and 1,4-xylene
diisocyanate; meta-tetramethylxylene diisocyanate;
para-tetramethylxylene diisocyanate; trimerized isocyanurate of any
polyisocyanate, such as isocyanurate of toluene diisocyanate,
trimer of diphenylmethane diisocyanate, trimer of tetramethylxylene
diisocyanate, isocyanurate of hexamethylene diisocyanate,
isocyanurate of isophorone diisocyanate, and mixtures thereof;
dimerized uredione of any polyisocyanate, such as uretdione of
toluene diisocyanate, uretdione of hexamethylene diisocyanate, and
mixtures thereof; modified polyisocyanate derived from the above
isocyanates and polyisocyanates; and mixtures thereof.
[0118] Examples of saturated diisocyanates that can be used with
the present invention include, but are not limited to, ethylene
diisocyanate; propylene-1,2-diisocyanate; tetramethylene
diisocyanate; tetramethylene-1,4-diisocyanate;
1,6-hexamethylene-diisocyanate; octamethylene diisocyanate;
decamethylene diisocyanate; 2,2,4-trimethylhexamethylene
diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate;
2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane
diisocyanate; 4,4'-dicyclohexyl diisocyanate; 2,4'-dicyclohexyl
diisocyanate; 1,3,5-cyclohexane triisocyanate;
isocyanatomethylcyclohexane isocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isocyanatoethylcyclohexane isocyanate;
bis(isocyanatomethyl)-cyclohexane diisocyanate;
4,4'-bis(isocyanatomethyl)dicyclohexane;
2,4'-bis(isocyanatomethyl)dicyclohexane; isophorone diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate; 4,4'-dicyclohexylmethane diisocyanate;
2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene
diisocyanate; and mixtures thereof. Aromatic aliphatic isocyanates
may also be used to form light stable materials. Examples of such
isocyanates include 1,2-, 1,3-, and 1,4-xylene diisocyanate;
meta-tetramethylxylene diisocyanate; para-tetramethylxylene
diisocyanate; trimerized isocyanurate of any polyisocyanate, such
as isocyanurate of toluene diisocyanate, trimer of diphenylmethane
diisocyanate, trimer of tetramethylxylene diisocyanate,
isocyanurate of hexamethylene diisocyanate, isocyanurate of
isophorone diisocyanate, and mixtures thereof; dimerized uredione
of any polyisocyanate, such as uretdione of toluene diisocyanate,
uretdione of hexamethylene diisocyanate, and mixtures thereof;
modified polyisocyanate derived from the above isocyanates and
polyisocyanates; and mixtures thereof. In addition, the aromatic
aliphatic isocyanates may be mixed with any of the saturated
isocyanates listed above for the purposes of this invention.
[0119] The number of unreacted NCO groups in the polyurea
prepolymer of isocyanate and polyether amine may be varied to
control such factors as the speed of the reaction, the resultant
hardness of the composition, and the like. For instance, the number
of unreacted NCO groups in the polyurea prepolymer of isocyanate
and polyether amine may be less than about 14 percent. In one
embodiment, the polyurea prepolymer has from about 5 percent to
about 11 percent unreacted NCO groups, and even more preferably has
from about 6 to about 9.5 percent unreacted NCO groups. In one
embodiment, the percentage of unreacted NCO groups is about 3
percent to about 9 percent. Alternatively, the percentage of
unreacted NCO groups in the polyurea prepolymer may be about 7.5
percent or less, and more preferably, about 7 percent or less. In
another embodiment, the unreacted NCO content is from about 2.5
percent to about 7.5 percent, and more preferably from about 4
percent to about 6.5 percent.
[0120] When formed, polyurea prepolymers may contain about 10
percent to about 20 percent by weight of the prepolymer of free
isocyanate monomer. Thus, in one embodiment, the polyurea
prepolymer may be stripped of the free isocyanate monomer. For
example, after stripping, the prepolymer may contain about 1
percent or less free isocyanate monomer. In another embodiment, the
prepolymer contains about 0.5 percent by weight or less of free
isocyanate monomer.
[0121] The polyether amine may be blended with additional polyols
to formulate copolymers that are reacted with excess isocyanate to
form the polyurea prepolymer. In one embodiment, less than about 30
percent polyol by weight of the copolymer is blended with the
saturated polyether amine. In another embodiment, less than about
20 percent polyol by weight of the copolymer, preferably less than
about 15 percent by weight of the copolymer, is blended with the
polyether amine. The polyols listed above with respect to the
polyurethane prepolymer, e.g., polyether polyols, polycaprolactone
polyols, polyester polyols, polycarbonate polyols, hydrocarbon
polyols, other polyols, and mixtures thereof, are also suitable for
blending with the polyether amine. The molecular weight of these
polymers may be from about 200 to about 4000, but also may be from
about 1000 to about 3000, and more preferably are from about 1500
to about 2500.
[0122] The polyurea composition can be formed by crosslinking the
polyurea prepolymer with a single curing agent or a blend of curing
agents. The curing agent of the invention is preferably an
amine-terminated curing agent, more preferably a secondary diamine
curing agent so that the composition contains only urea linkages.
In one embodiment, the amine-terminated curing agent may have a
molecular weight of about 64 or greater. In another embodiment, the
molecular weight of the amine-curing agent is about 2000 or less.
As discussed above, certain amine-terminated curing agents may be
modified with a compatible amine-terminated freezing point
depressing agent or mixture of compatible freezing point depressing
agents.
[0123] Suitable amine-terminated curing agents include, but are not
limited to, ethylene diamine; hexamethylene diamine;
1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene
diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,4-bis-(sec-butylamino)-cyclohexane;
1,2-bis-(sec-butylamino)-cyclohexane; derivatives of
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
4,4'-dicyclohexylmethane diamine;
1,4-cyclohexane-bis-(methylamine);
1,3-cyclohexane-bis-(methylamine); diethylene glycol
di-(aminopropyl)ether; 2-methylpentamethylene-diamine;
diaminocyclohexane; diethylene triamine; triethylene tetramine;
tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;
dimethylamino propylamine; diethylamino propylamine; dipropylene
triamine; imido-bis-propylamine; monoethanolamine, diethanolamine;
triethanolamine; monoisopropanolamine, diisopropanolamine;
isophoronediamine; 4,4'-methylenebis-(2-chloroaniline);
3,5;dimethylthio-2,4-toluenediamine;
3,5-dimethylthio-2,6-toluenediamine;
3,5-diethylthio-2,4-toluenediamine;
3,5;diethylthio-2,6-toluenediamine;
4,4'-bis-(sec-butylamino)-diphenylmethane and derivatives thereof;
1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene;
N,N'-dialkylamino-diphenylmethane;
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylene diamine;
trimethyleneglycol-di-p-aminobenzoate;
polytetramethyleneoxide-di-p-aminobenzoate;
4,4'-methylenebis-(3-chloro-2,6-diethyleneaniline);
4,4'-methylenebis-(2,6-diethylaniline); meta-phenylenediamine;
paraphenylenediamine; and mixtures thereof. In one embodiment, the
amine-terminated curing agent is
4,4'-bis-(sec-butylamino)-dicyclohexylmethane.
[0124] Suitable saturated amine-terminated curing agents include,
but are not limited to, ethylene diamine; hexamethylene diamine;
1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene
diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,4-bis-(sec-butylamino)-cyclohexane;
1,2-bis-(sec-butylamino)-cyclohexane; derivatives of
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
4,4'-dicyclohexylmethane diamine;
4,4'-methylenebis-(2,6-diethylaminocyclohexane;
1,4-cyclohexane-bis-(methylamine);
1,3-cyclohexane-bis-(methylamine); diethylene glycol
di-(aminopropyl)ether; 2-methylpentamethylene-diamine;
diaminocyclohexane; diethylene triamine; triethylene tetramine;
tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;
dimethylamino propylamine; diethylamino propylamine;
imido-bis-propylamine; monoethanolamine, diethanolamine;
triethanolamine; monoisopropanolamine, diisopropanolamine;
isophoronediamine; triisopropanolamine; and mixtures thereof. In
addition, any of the polyether amines listed above may be used as
curing agents to react with the polyurea prepolymers.
[0125] Cover layers of the inventive golf ball may also be formed
from ionomeric polymers, preferably highly-neutralized ionomers
(HNP). In a preferred embodiment, at least one intermediate layer
of the golf ball is formed from an HNP material or a blend of HNP
materials. The acid moieties of the HNP's, typically ethylene-based
ionomers, are preferably neutralized greater than about 70%, more
preferably greater than about 90%, and most preferably at least
about 100%. The HNP's can be also be blended with a second polymer
component, which, if containing an acid group, may be neutralized
in a conventional manner, by the organic fatty acids of the present
invention, or both. The second polymer component, which may be
partially or fully neutralized, preferably comprises ionomeric
copolymers and terpolymers, ionomer precursors, thermoplastics,
polyamides, polycarbonates, polyesters, polyurethanes, polyureas,
thermoplastic elastomers, polybutadiene rubber, balata,
metallocene-catalyzed polymers (grafted and non-grafted),
single-site polymers, high-crystalline acid polymers, cationic
ionomers, and the like. HNP polymers typically have a material
hardness of between about 20 and about 80 Shore D, and a flexural
modulus of between about 3,000 psi and about 200,000 psi.
[0126] In one embodiment of the present invention the HNP's are
ionomers and/or their acid precursors that are preferably
neutralized, either filly or partially, with organic acid
copolymers or the salts thereof. The acid copolymers are preferably
.alpha.-olefin, such as ethylene, C.sub.3-8
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, such as
acrylic and methacrylic acid, copolymers. They may optionally
contain a softening monomer, such as alkyl acrylate and alkyl
methacrylate, wherein the alkyl groups have from 1 to 8 carbon
atoms.
[0127] The acid copolymers can be described as E/X/Y copolymers
where E is ethylene, X is an .alpha.,.beta.-ethylenically
unsaturated carboxylic acid, and Y is a softening comonomer. In a
preferred embodiment, X is acrylic or methacrylic acid and Y is a
C.sub.1-8 alkyl acrylate or methacrylate ester. X is preferably
present in an amount from about 1 to about 35 weight percent of the
polymer, more preferably from about 5 to about 30 weight percent of
the polymer, and most preferably from about 10 to about 20 weight
percent of the polymer. Y is preferably present in an amount from
about 0 to about 50 weight percent of the polymer, more preferably
from about 5 to about 25 weight percent of the polymer, and most
preferably from about 10 to about 20 weight percent of the
polymer.
[0128] Specific acid-containing ethylene copolymers include, but
are not limited to, ethylene/acrylic acid/n-butyl acrylate,
ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic
acid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,
ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic
acid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,
ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylic
acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl
methacrylate. Preferred acid-containing ethylene copolymers
include, ethylene/methacrylic acid/n-butyl acrylate,
ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic
acid/methyl acrylate, ethylene/acrylic acid/ethyl acrylate,
ethylene/methacrylic acid/ethyl acrylate, and ethylene/acrylic
acid/methyl acrylate copolymers. The most preferred acid-containing
ethylene copolymers are, ethylene/(meth)acrylic acid/n-butyl,
acrylate, ethylene/(meth)acrylic acid/ethyl acrylate, and
ethylene/(meth)acrylic acid/methyl acrylate copolymers.
[0129] Ionomers are typically neutralized with a metal cation, such
as Li, Na, Mg, K, Ca, or Zn. It has been found that by adding
sufficient organic acid or salt of organic acid, along with a
suitable base, to the acid copolymer or ionomer, however, the
ionomer can be neutralized, without losing processability, to a
level much greater than for a metal cation. Preferably, the acid
moieties are neutralized greater than about 80%, preferably from
90-100%, most preferably 100% without losing processability. This
accomplished by melt-blending an ethylene
.alpha.,.beta.-ethylenically unsaturated carboxylic acid copolymer,
for example, with an organic acid or a salt of organic acid, and
adding a sufficient amount of a cation source to increase the level
of neutralization of all the acid moieties (including those in the
acid copolymer and in the organic acid) to greater than 90%,
(preferably greater than 100%).
[0130] The organic acids of the present invention are aliphatic,
mono- or multi-functional (saturated, unsaturated, or
multi-unsaturated) organic acids. Salts of these organic acids may
also be employed. The salts of organic acids of the present
invention include the salts of barium, lithium, sodium, zinc,
bismuth, chromium, cobalt, copper, potassium, strontium, titanium,
tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin,
or calcium, salts of fatty acids, particularly stearic, behenic,
erucic, oleic, linoelic or dimerized derivatives thereof. It is
preferred that the organic acids and salts of the present invention
be relatively non-migratory (they do not bloom to the surface of
the polymer under ambient temperatures) and non-volatile (they do
not volatilize at temperatures required for melt-blending).
[0131] The ionomers of the invention may also be more conventional
ionomers, i.e., partially-neutralized with metal cations. The acid
moiety in the acid copolymer is neutralized about 1 to about 90%,
preferably at least about 20 to about 75%, and more preferably at
least about 40 to about 70%, to form an ionomer, by a cation such
as lithium, sodium, potassium, magnesium, calcium, barium, lead,
tin, zinc, aluminum, or a mixture thereof.
[0132] In a preferred embodiment, the inventive single-layer core
is enclosed with two cover layers, where the inner cover layer has
a thickness of about 0.01 inches to about 0.06 inches, more
preferably about 0.015 inches to about 0.040 inches, and most
preferably about 0.02 inches to about 0.035 inches, and the inner
cover layer is formed from a partially- or fully-neutralized
ionomer having a Shore D hardness of greater than about 55, more
preferably greater than about 60, and most preferably greater than
about 65. In this embodiment, the outer cover layer should have a
thickness of about 0.015 inches to about 0.055 inches, more
preferably about 0.02 inches to about 0.04 inches, and most
preferably about 0.025 inches to about 0.035 inches, and has a
hardness of about Shore D 60 or less, more preferably 55 or less,
and most preferably about 52 or less. The inner cover layer should
be harder than the outer cover layer. In this embodiment the outer
cover layer comprises a partially- or fully-neutralized iononomer,
a polyurethane, polyurea, or blend thereof. A most preferred outer
cover layer is a castable or reaction injection molded
polyurethane, polyurea or copolymer or hybrid thereof having a
Shore D hardness of about 40 to about 50. A most preferred inner
cover layer material is a partially-neutralized ionomer comprising
a zinc, sodium or lithium neutralized ionomer such as SURLYN.RTM.
8940, 8945, 9910, 7930, 7940, or blend thereof having a Shore D
hardness of about 63 to about 68.
[0133] In another multi-layer cover, single core embodiment, the
outer cover and inner cover layer materials and thickness are the
same but, the hardness range is reversed, that is, the outer cover
layer is harder than the inner cover layer.
[0134] In an alternative preferred embodiment, the golf ball is a
one-piece golf ball having a dimpled surface and having a surface
hardness equal to or less than the center hardness (i.e., a
negative hardness gradient). The one-piece ball preferably has a
diameter of about 1.680 inches to about 1.690 inches, a weight of
about 1.620 oz, an Atti compression of from about 40 to 120, and a
COR of about 0.750-0.825.
[0135] In a preferred two-piece ball embodiment, the single-layer
core having a negative hardness gradient is enclosed with a single
layer of cover material having a Shore D hardness of from about 20
to about 80, more preferably about 40 to about 75 and most
preferably about 45 to about 70, and comprises a thermoplastic or
thermosetting polyurethane, polyurea, polyamide, polyester,
polyester elastomer, polyether-amide or polyester-amide, partially
or fully neutralized ionomer, polyolefin such as polyethylene,
polypropylene, polyethylene copolymers such as ethylene-butyl
acrylate or ethylene-methyl acrylate, poly(ethylene methacrylic
acid) co-and terpolymers, metallocene-catalyzed polyolefins and
polar-group functionalized polyolefins and blends thereof. A
preferred cover material in the two-piece embodiment is an ionomer
(either conventional or HNP) having a hardness of about 50 to about
70 Shore D. Another preferred cover material in the two-piece
embodiment is a thermoplastic or thermosetting polyurethane or
polyurea. A preferred ionomer is a high acid ionomer comprising a
copolymer of ethylene and methacrylic or acrylic acid and having an
acid content of at least 16 to about 25 weight percent. In this
case the reduced spin contributed by the relatively rigid high acid
ionomer may be offset to some extent by the spin-increasing
negative gradient core. The core may have a diameter of about 1.0
inch to about 1.64 inches, preferably about 1.30 inches to about
1.620, and more preferably about 1.40 inches to about 1.60
inches.
[0136] Another preferred cover material comprises a castable or
reaction injection moldable polyurethane, polyurea, or copolymer or
hybrid of polyurethane/polyurea. Preferably, this cover is
thermosetting but may be a thermoplastic, having a Shore D hardness
of about 20 to about 70, more preferably about 30 to about 65 and
most preferably about 35 to about 60. A moisture vapor barrier
layer, such as disclosed in U.S. Pat. Nos. 6,632,147; 6,932,720;
7,004,854; and 7,182,702, all of which are incorporated by
reference herein in their entirety, is optionally employed between
the cover layer and the core.
[0137] While any of the embodiments herein may have any known
dimple number and pattern, a preferred number of dimples is 252 to
456, and more preferably is 330 to 392. The dimples may comprise
any width, depth, and edge angle disclosed in the prior art and the
patterns may comprises multitudes of dimples having different
widths, depths and edge angles. The parting line configuration of
said pattern may be either a straight line or a staggered wave
parting line (SWPL). Most preferably the dimple number is 330, 332,
or 392 and comprises 5 to 7 dimples sizes and the parting line is a
SWPL.
[0138] In any of these embodiments the single-layer core may be
replaced with a 2 or more layer core wherein at least one core
layer has a negative hardness gradient.
Other than in the operating examples, or unless otherwise expressly
specified, all of the numerical ranges, amounts, values and
percentages such as those for amounts of materials and others in
the specification may be read as if prefaced by the word "about"
even though the term "about" may not expressly appear with the
value, amount or range. Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques.
[0139] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contain certain errors necessarily resulting from the
standard deviation found in their respective testing measurements.
Furthermore, when numerical ranges of varying scope are set forth
herein, it is contemplated that any combination of these values
inclusive of the recited values may be used.
[0140] While it is apparent that the illustrative embodiments of
the invention disclosed herein fulfill the objective stated above,
it is appreciated that numerous modifications and other embodiments
may be devised by those skilled in the art. Therefore, it will be
understood that the appended claims are intended to cover all such
modifications and embodiments, which would come within the spirit
and scope of the present invention.
* * * * *