Note: Descriptions are shown in the official language in which they were submitted.
CA 02288405 1999-11-10
HIGH ACID IONOMERS AND GOLF BALL
COVER COMPOSITIONS COMPRISING SAME
This application is a division of copending
Application No. 2,088,140 filed in Canada on
January 26, 1993.
Field of the Invention
The present invention relates to new metal .cation
neutralized high acid ionomer resins and to improved golf
ball covers made from these resins. The improved golf ball
covers are useful for producing golf balls, particularly
multi-piece balls, exhibiting enhanced travel distance
while maintaining the playability and/or durability
characteristics necessary for repetitive play.
Background of the Invention
Ionomeric resins are polymers containing interchain
ionic bonding. As a result of their toughness, durability,
and flight characteristics, various ionomeric resins sold
by E.I. DuPont de Nemours & Company under the trademark
"Surlyn°" and more recently, by the Exxon Corporation (see
U.S. Patent No. 4,911,451) under the trademarks "Escor°"
and the tradename "Iotek", have become the materials of
choice for the construction of golf ball covers over the
traditional "balata" (trans polyisoprene, natural or
synthetic) rubbers. The softer balata covers, although
exhibiting enhanced playability properties, lack the
durability properties required for repetitive play.
Ionomeric resins are generally ionic copolymers of an
olefin, such as ethylene, and a metal salt of an
unsaturated carboxylic acid, such as acrylic acid,
methacrylic acid or malefic acid. In some instances, an
additional softening comonomer such as an acrylate can also
CA 02288405 1999-11-10
2
be included to form a terpolymer. The pendent ionic groups
in the ionomeric resins interact to form ion-rich
aggregates contained in a non-polar polymer matrix. The
metal ions, such as sodium, zinc, magnesium, lithium,
potassium, calcium, etc. are used to neutralize some
portion of the acid groups in the copolymer resulting in a
thermoplastic elastomer exhibiting enhanced properties,
i.e. improved durability, etc. for golf ball construction
over balata.
Broadly, the ionic copolymers comprise one or more
alpha-olefins and from about 9 to about 20 weight percent
of alpha, beta-ethylenically unsaturated mono- or
dicarboxylic acid, the basic copolymer neutralized with
metal ions to the extent desired. Usually, at least 20% of
the carboxylic acid groups of the copolymer are neutralized
by the metal ions (such as sodium, potassium, zinc,
calcium, magnesium, and the like) and exist in the ionic
state.
Suitable olefins for use in preparing the ionomeric
resins include ethylene, propylene, butene-1, hexene-1, and
the like. Unsaturated carboxylic acids include acrylic,
methacrylic, ethacrylic, a-chloroacrylic, crotonic, malefic,
fumaric, itaconic acids, and the like. The ionomeric
resins utilized in the golf ball industry are generally
copolymers of ethylene with acrylic (i.e. Escor°) and/or
methacrylic (i.e. Surlyn°) acid. In addition, two or more
types of ionomeric resins may be blended into the cover
compositions in order to produce the desired properties of
the resulting golf balls.
Along this line, the properties of the cover
compositions and/or the ionomeric resins utilized in the
golf ball industry vary according to the type and amount of
the metal cation, the molecular weight, the composition of
the base resin (i.e. the nature and the relative content of
the olefin, the unsaturated carboxylic acid groups, etc.),
the amount of acid, the degree of neutralization and
CA 02288405 1999-11-10
3
whether additional ingredients such as reinforcement agents
or additives are utilized. Consequently, the properties of
the ionomer resins can be controlled and varied in order to
produce golf balls having different playing
characteristics, such as differences in hardness,
playability (i.e. spin, feel, click, etc.), durability
(i.e. impact and/or cut resistance), and resilience (i.e.
coefficient of restitution).
However, while there are currently more than fifty
commercial grades of ionomers available from DuPont and
Exxon with a wide range of properties which vary according
to the type and amount of metal cations, molecular weight,
composition of the base resin (i.e. relative content of
ethylene and methacrylic and/or acrylic acid groups), the
degree of neutralization and additive ingredients such as
reinforcement agents, etc., a great deal of research
continues in order to develop golf ball cover compositions
exhibiting not only the playability characteristics
previously associated with the balata cover, but also the
improved impact resistance and carrying distance properties
produced by the ionomeric resins. Thus, an object of the
present invention is to provide golf ball cover
compositions which, when utilized in golf ball
construction, produce balls exhibiting improved travel
distance while maintaining satisfactory playability and
durability properties.
In enhancing the distance a golf ball will travel when
hit, there are a variety of factors which are considered.
The coefficient of restitution, along with ball size,
weight and additional factors such as club head speed,
angle of trajectory, and ball aerodynamics (i.e., dimple
pattern), generally determine the distance a ball will
travel when hit. Since club head speed and the angle of
trajectory are not factors easily controllable,
particularly by golf ball manufacturers, the factors of
CA 02288405 1999-11-10
4
concern among manufacturers are the coefficient of
restitution and the surface dimple pattern of the ball.
A golf ball's coefficient of restitution (C.O.R.) is
the ratio of the relative velocity of the ball after direct
impact to that before impact. One way to measure the
coefficient of restitution is to propel a ball at a given
speed against a hard massive surface, and measure its
incoming velocity and outgoing velocity. The coefficient
of restitution is defined as the ratio of the outgoing
velocity to incoming velocity of a rebounding ball and is
expressed as a decimal. As a result, the coefficient of
-restitution can vary from zero to one, with one being
equivalent to an elastic collision and zero being
equivalent to an inelastic collision.
The coefficient of restitution of a one-piece golf
ball is a function of the ball's composition. In a two-
piece or a multi-layered golf ball, the coefficient of
restitution is a function of the core, the cover and any
additional layer. While there are no United States Golf
Association (U.S.G.A.) limitations on the coefficient of
restitution values of a golf ball, the U.S.G.A. requires
that the golf ball cannot exceed an initial velocity of 255
feet/second. As a result, golf ball manufacturers
generally seek to maximize the coefficient of restitution
of a ball without violating the velocity limitation.
In various attempts to produce a high coefficient of
restitution golf ball exhibiting the enhanced travel
distance desired, the golfing industry has blended various
ionomeric resins. However, many of these blends do not
exhibit the durability and playability characteristics
necessary for repetitive play and/or the enhanced travel
distance desired.
The present invention is directed to the preparation
of new cation neutralized ionomer resins containing
relative high amounts of acid (i.e. greater than 16 weight
percent acid, preferably from about 17 to about 25 weight
CA 02288405 1999-11-10
percent acid, and more preferably from about 18.5 to about
21.5 weight percent acid) and partially neutralized with
sodium, manganese, lithium, potassium, zinc, magnesium
calcium and nickel ions. The new cation neutralized high
5 acid ionomers produce, when blended and melt processed
according to the parameters set forth below, cover
compositions exhibiting enhanced coefficient of restitution
values when compared to low acid ionomers, or blends of low
acid ionomer resins containing 16 weight percent acid or
less . The new high acid ionomer cover compositions produce
golf balls which exhibit properties of enhanced carrying
distance (i.e. possess higher coefficient of restitution
values) over known ionomer blends such as those set forth
in U.S. Patent Nos. 4,884,814 and 4,911,451, without
sacrificing desirable characteristics such as playability
and/or durability.
Along this line, until relatively recently, all of the
ionomer resins commercially available contained at most 15
to 16 weight percent carboxylic acid. In 1989, DuPont
introduced a number of new high acid ionomers and suggested
that these new ionomers may have some use in previously
known low acid ionomer applications such as the production
of shoe soles, box toes, bowling pins, golf balls, ski
boots, auto trim, etc.
Furthermore, DuPont suggested in a research disclosure
(E.I. DuPont de Nemours & Co., Research Disclosure No.
297,003) that ionomers produced from polymers of ethylene
acrylic acid or methacrylic acid containing greater than 15
weight percent acid can be melt processed to produce
articles (i.e. golf balls, foot wear, ski boots, cosmetic
bottle cap closures and so on) with good properties (i.e.
improved stiffness, hardness and clarity) when compared
with ionomers with lower acid levels.
However, not only has little information been provided
concerning the acid levels and types of effective ionomers,
particularly with respect to the art of golf ball
CA 02288405 1999-11-10
6
manu~acturing, it has been found that many cover
compositions produced from polymers of ethylene/acryli.c
acid or ethylene/methacrylic acid containing greater than
15 weight percent acid have been dissatisfactory in that
these compositions exhibit processing problems or are
generally short on distance and/or durability and thus, are
not particularly commercially viable. Similar poor results
have been produced with covers composed of blends of high
and low acid ethylene/acrylic acid or ethylene/methacrylic
acid polymers and/or covers produced from single high acid
ionomers.
However, notwithstanding the above difficulties, it
has been discovered that improved golf ball covers can be
produced from specific blends of high acid ionomers (i.e.
ionomer resins containing greater than 16 weight percent
acid, preferably from about 17 to about 25 weight percent
acid, and more preferably from about 18.5 to about 21.5
weight percent acid) which do not exhibit the processing,
distance and/or durability limitations demonstrated by the
prior art.
In this regard, it has been found that blends of
specific high acid ionomer resins, particularly blends of
sodium and zinc high acid ionomers, as well as blends of
sodium and magnesium high acid ionomers, extend, when
utilized in golf ball cover construction, the range of
hardness beyond that previously obtainable while
maintaining the beneficial properties (i.e. durability,
click, feel, etc.) of the softer low acid ionomers
disclosed in U.S. Patent Nos. 4,884,814 and 4,911,451.
These blends produce harder, stiffer golf balls having
higher C.O.R.s, and thus longer distance. This discovery
is the subject matter of copending Canadian
Application No. 2,078,842.
The present invention is directed to the development
of a number of new high acid ionomers, particularly new
CA 02288405 1999-11-10
7
metal cation neutralized acrylic acid based high acid
ionomer resins, which exhibit, when utilized for golf ball
cover construction, cover compositions having further
improved hardness and resilience (C.O.R.) properties. The
new metal cation neutralized acrylic acid based high acid
ionomer resins, as well as specific blends of these resins,
are particularly valuable in the field of golf ball
production.
Furthermore, as a result of the development of a
number of new acrylic acid based high acid ionomers
neutralized to various extents by several different types
of metal cations, such as by manganese, lithium, potassium,
calcium and nickel cations, several new high acid ionomers
and/or high acid ionomer blends besides sodium, zinc and
magnesium high acid ionomers or ionomer blends are now
available for golf ball cover production. It has been
found that many of. these new cation neutralized high acid
ionomer blends produce cover compositions exhibiting
enhanced resilience (i.e. longer distance) due to synergies
which occur during processing. Consequently, the new metal
cation neutralized acrylic acid based high acid ionomer
resins of the present invention may be blended to produce
substantially harder golf balls having higher C.O.R.'s than
those produced by the low acid ionomer covers presently
commercially available.
These and other objects and features of the invention
will be apparent from the following description and from
the claims.
Summary of the Invention
In one aspect, the present invention is directed to
new metal cation neutralized high acid ionomer resins
comprising a copolymer of greater than 16% by weight of an
alpha, beta-unsaturated carboxylic acid (preferably from
about 17% to about 25% by weight acid, and more preferably
from about 18.5% to about 21.5% by weight acid) and an
alpha-olefin, of which about 10% to about 90% of the
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carboxyl groups of the copolymer are neutralized with a
metal cation selected from the group consisting of
manganese, lithium, potassium, calcium and nickel.
In another aspect, the invention relates to metal
cation neutralized high acid ionomer resins comprising a
copolymer of about 20% by weight of an alpha, beta
unsaturated carboxylic acid (preferably acrylic acid) and
an olefin (preferably ethylene), of which about 10% to
about 90% of the carboxyl groups of the copolymer are
neutralized with a metal cation selected from the group
consisting of manganese, lithium, potassium, calcium and
nickel.
In a further aspect, the present invention concerns a
metal cation neutralized high acid ionomer resins
comprising a copolymer of about 20% by weight acrylic acid
with the remainder, or balance, thereof being ethylene, of
which 10% to 90% of the carboxyl groups of the copolymer
are neutralized with a metal cation selected from the group
consisting of manganese, lithium, potassium, magnesium,
calcium and nickel.
In still another aspect, the invention is directed to
a metal cation neutralized high acid ionomer resin
comprising a copolymer of about 20% by weight acrylic acid
and the remainder ethylene, of which 10% to 90% of the
carboxyl groups of the copolymer are neutralized with a
metal cation selected from the group consisting of sodium,
manganese, lithium, potassium, zinc, magnesium, calcium and
nickel. The metal cation neutralized high acid ionomer
resin produces, when blended and molded around solid or
wound cores to form a cover composition, golf balls
exhibiting enhanced resilience (i.e. improved C.O.R.)
without adversely affecting the ball's playability and/or
durability characteristics.
In an additional aspect, the invention relates to a
method for producing metal cation neutralized high acid
ionomer resins comprising the steps of providing a
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copolymer comprised of greater than 16% by weight of an
alpha, beta-unsaturated carboxylic acid and an olefin; and
neutralizing from about 10% to about 90% of the carboxylic
acid groups of the copolymer with a metal cation selected
from the group consisting of manganese, lithium, potassium,
calcium and nickel. The metal cation neutralized high acid
ionomer resins produced by this method are also provided.
In another aspect, the present invention concerns a
process for producing metal cation neutralized acrylic acid
based high acid ionomer resins comprising the steps of
providing a copolymer made of about 20% by weight of
acrylic acid and the balance ethylene, and neutralizing
from about 10% to about 90% of the carboxylic acid groups
of the copolymer with a metal cation selected from the
group consisting of manganese, lithium, potassium,
magnesium, calcium and nickel. The new metal cation
neutralized high acid ionomer resins produced by this
method are also provided.
In still a further aspect, the invention is directed
to a golf ball comprising a core and a cover, wherein the
cover is comprised of a metal cation neutralized high acid
ionomer resin which is a copolymer of greater than 16% by
weight of an alpha, beta-unsaturated carboxylic acid,
(preferably from about 17% to about 25% by weight acid, and
more preferably from about 18.5% to about 21.5% by weight
acid) and an olefin, of which 10% to 90% of the carboxyl
groups of the copolymer are neutralized with a metal cation
selected from the group consisting of manganese, lithium,
potassium, calcium and nickel. In addition, the cover may
contain of one or more additional ingredients such as
pigments, dyes, U.V. absorbers and optical brighteners.
In another further aspect, the invention relates to a
golf ball comprising a core and a cover, wherein the cover
is comprised of a metal cation neutralized ionomer resin
which is a copolymer of about 20% by weight of an acrylic
acid and the remainder ethylene, of which loo to 90% of the
CA 02288405 1999-11-10
carboxyl groups of the acrylic acid/ethylene copolymer are
neutralized with a metal cation selected from the group
consisting of manganese, lithium, potassium, magnesium,
calcium and nickel. The core is generally a solid core,
5 and additional ingredients such as pigments, dyes, U.v.
absorbers and optical brighteners may be included in the
cover.
In a further additional aspect, the invention is
directed to a golf ball comprising a core and a cover,
10 wherein the cover is a blend of two or more metal cation
neutralized high acid ionomer resins, each ionomer resin
comprised of about 20% by weight of acrylic acid and the
remainder ethylene, of which about 10% to about 90% of the
carboxyl groups of the copolymer are neutralized with a
metal cation. The metal cation of each resin is a cation
selected from the group consisting of sodium, manganese,
lithium, potassium, zinc, magnesium, calcium and nickel.
In this regard, diblends consisting of sodium/manganese,
sodium/lithium, sodium/zinc, sodium/magnesium,
sodium/calcium, manganese/potassium, lithium/zinc,
lithium/magnesium,lithium/calcium,and potassium/magnesium
neutralized 20% acrylic acid/ethylene ionomer resins and
triblends consisting of zinc/lithium/potassium,
sodium/zinc/lithium, sodium/manganese/calcium,
sodium/potassium/manganese, and sodium/potassium/magnesium
neutralized 20% acrylic acid/ethylene ionomer resins are
the more preferred blends which comprise the cover
component of the invention.
Further scope of the applicability of the present
invention will become apparent from the detailed
description given hereinafter. However, it should be
understood that the detailed description and specific
examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since
various changes and modifications within the spirit and
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11
scope of the invention will become apparent to those
skilled in the art.
Detailed Description of the Invention
The present invention relates to the development of a
number of new metal cation neutralized high acid ionomers.
In addition, the present invention relates to the use of
these new metal cation neutralized high acid ionomers,
and/or blends thereof, for the purpose of producing golf
ball covers exhibiting enhanced resilience and/or hardness
characteristics.
In this regard, several new metal cation neutralized
high acid ionomer resins have been produced by
neutralizing, to various extents, high acid copolymers of
an alpha-olefin and an alpha, beta-unsaturated carboxylic
acid with a wide variety of different metal cation salts.
More particularly, it has been found that numerous new
metal cation neutralized high acid ionomer resins can be
obtained by reacting a high acid copolymer (i.e. a
copolymer containing greater than 16% by weight acid,
preferably from about 17 to about 25 weight percent acid,
and more preferably about 20 weight percent acid), with a
metal cation salt capable of ionizing or neutralizing the
copolymer to the extent desired (i.e. from about 10% to
90%).
The base copolymer is made up of greater than 16% by
weight of an alpha, beta-unsaturated carboxylic acid and an
alpha-olefin. Optionally, a softening comonomer can be
included in the copolymer. Generally, the alpha-olefin has
from 2 to 10 carbon atoms and is preferably ethylene, and
the unsaturated carboxylic acid is a carboxylic acid having
from about 3 to 8 carbons. Examples of such acids include
acrylic acid, methacrylic acid, ethacrylic acid,
chloroacrylic acid, crotonic acid, malefic acid, fumaric
acid, and itaconic acid, with acrylic acid being preferred.
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The softening comonomer that can be optionally
included in the invention may be selected from the group
consisting of vinyl esters of aliphatic carboxylic acids
wherein the acids have 2 to 10 carbon atoms, vinyl ethers
wherein the alkyl groups contains 1 to 10 carbon atoms, and
alkyl acrylates or methacrylates wherein the alkyl group
contains 1 to 10 carbon atoms. Suitable softening
comonomers include vinyl acetate, methyl acrylate, methyl
methacrylate, ethyl acrylate, ethyl methacrylate, butyl
acrylate, butyl methacrylate, or the like.
Consequently, examples of a number of copolymers
suitable for use in the invention include, but are not
limited to, high acid embodiments of an ethylene/acrylic
acid copolymer, an ethylene/methacrylic acid copolymer, an
ethylene/itaconic acid copolymer, an ethylene/maleic acid
copolymer, an ethylene/methacrylic acid/vinyl acetate
copolymer, an ethylene/acrylic acid/vinyl alcohol
copolymer, etc. The base copolymer broadly contains
greater than 16% by weight unsaturated carboxylic acid,
from about 30 to about 83% by weight ethylene and from 0 to
about 40% by weight of a softening comonomer. Preferably,
the copolymer contains about 20% by weight unsaturated
carboxylic acid and about 80% by weight ethylene. Most
preferably, the copolymer contains about 20% acrylic acid
with the remainder being ethylene.
Along these lines, examples of the preferred high acid
base copolymers which fulfill the criteria set forth above,
are a series of ethylene-acrylic copolymers which are
commercially available from The Dow Chemical Company,
Midland, Michigan, under the "Primacor" designation. These
high acid base copolymers exhibit the typical properties
set forth below in Table 1.
*Trade-mark
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TABLE 1
Typical Properties of Primacor
Ethylene-Acrylic Acid Copolymers
GRADE PERCENTDENSITY,HELT TENSILEFIEXURAIVICAT SHORE
ACID glcc INDEX,YD. HODULUSSOFT D
g/l0minST (psi) PT HARDNESS
(psi) ('C)
ASTH 0-T92 D-1238D-638 D-790 D-1525D-2240
5980 20.0 0.958 300.0 - 4800 43 50
5990 Z0.0 0.955 1300.0650 2600 40 42
5990 20.0 0.955 1300.0b50 3200 40 42
5981 20.0 0.960 300.0 900 3200 46 48
1 0 5981 20.0 0.960 300.0 900 3200 46 48
5983 20.0 0.958 500.0 850 3100 44 45
5991 20.0 0.953 2600.0635 2600 38 ~.0
The Nelt Index values are obtained according to ASTH 0-1238, at 190'C.
Due to the high molecular weight of the Primacor 5981
grade of the ethylene-acrylic acid copolymer, this
copolymer is the more preferred grade utilized in the
invention.
The metal cation salts utilized in the invention are
those salts which provide the metal cations capable of
neutralizing, to various extents, the carboxylic acid
groups of the high acid copolymer. These include acetate,
oxide or hydroxide salts of lithium, calcium, zinc, sodium,
potassium, nickel, magnesium, and manganese.
Examples of such lithium ion sources are lithium
hydroxide monohydrate, lithium hydroxide, lithium oxide and
lithium acetate. Sources for. the calcium ion include
calcium hydroxide, calcium acetate and calcium oxide.
Suitable zinc ion sources are zinc acetate dihydr_ate and
zinc acetate, a blend of zinc oxide and acetic acid.
Examples of sodium ion sources are sodium hydroxide and
sodium acetate. Sources for the potassium ion include
potassium hydroxide and potassium acetate. Suitable nickel
ion sources are nickel acetate, nickel oxide and nickel
hydroxide. Sources of magnesium include magnesium oxide,
CA 02288405 1999-11-10
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magnesium hydroxide, magnesium acetate. Sources of
manganese include manganese acetate and manganese oxide.
The new metal cation neutralized high acid ionomer
resins of the invention are produced by reacting the high
acid base copolymer with various amounts of the metal
cation salts above the crystalline melting point of the
copolymer, such as at a temperature from about 200° F to
about 500° F, preferably from about 250° F to about 350°
F
under high shear conditions at a pressure of from about 100
psi to 10,000 psi. Other well known blending techniques
may also be used. The amount of metal cation salt utilized
to produce the new metal cation neutralized high acid based
ionomer resins is the quantity which provides a sufficient
amount of the metal cations to neutralize the desired
percentage of the carboxylic acid groups in the high acid
copolymer. The extent of neutralization is generally from
about 10% to about 90%.
As indicated more specifically in Example 1 below, a
number of new types of metal cation neutralized high acid
ionomers can be obtained from the process of this
invention. These include new high acid ionomer resins
neutralized to various extents with manganese, lithium,
potassium, calcium and nickel cations. In addition, when
a high acid ethylene/acrylic acid copolymer is utilized as
the base copolymer component of the invention and this
component is subsequently neutralized to various extents
with the metal cation salts producing acrylic acid based
high acid ionomer resins neutralized with cations such as
sodium, potassium, lithium, zinc, magnesium, manganese,
calcium and nickel, several new cation neutralized acrylic
acid based high acid ionomer resins are produced.
When compared to low acid versions of similar cation
neutralized ionomer resins, the new metal cation
neutralized high acid ionomer resins exhibit enhanced
hardness, modulus and resilience characteristics. These
are properties that are particularly desirable in a number
CA 02288405 1999-11-10
of thermoplastic fields, including the field golf ball
manufacturing.
When utilized in golf ball cover construction, it has
been found that the new acrylic acid based high acid
5 ionomers extend the range of hardness beyond that
previously obtainable while maintaining the beneficial
properties (i.e. durability, click, feel, etc.) of the
softer low acid ionomer covered balls, such as balls
produced utilizing the low acid ionomers disclosed in U.S.
10 Patent Nos. 4,884,814 and 4,911,451, and the recently
produced high acid blends disclosed in copending
Canadian Application No. 2,078,842.
Moreover, as a result of the development of a number
of new acrylic acid based high acid ionomer resins
15 neutralized to various extents by several different types
of metal cations, such as manganese, lithium, potassium,
calcium and nickel cations, several new ionomers or ionomer
blends are now available for golf ball production. By
using the high acid ionomer resins of the present
invention, harder, stiffer golf balls having higher
C.O.R.s, and thus longer distance, can be obtained.
Examples of existing high acid methacrylic acid based
ionomers include Surlyn~ AD-8422 (sodium cation), Surlyn°
8162 (zinc cation), Surlyn° SEP-503-1 (an experimental zinc
cation), and Surlyn° SEP-503-2 (an experimental magnesium
cation). According to DuPont, all of these ionomers
contain from about 18.5% to about 21.5% by weight
methacrylic acid.
More particularly, Surlyn° AD-8422, is currently
commercially available from DuPont in a number of different
grades (i.e. AD-8422-2, AD-8422-3, AD-8422-5, etc.) based
upon differences in melt index. According to DuPont,
Surlyn° AD-8422 offers the following general properties
when compared to Surlyn° 8920 the stiffest, hardest of all
of the low acid grades (referred to as "hard" ionomers in
U.S. Patent No. 4,884,814):
CA 02288405 1999-11-10
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TABLE 2
LOW ACID HIGH ACID
(15 wt% Acid) (>20 wt% Acid)
SURLYN SURLYN SURLYN
8920 8422-2 8422-3
I ONOMER
Cation Na Na Na
Melt Index 1.2 2.8 1.0
Sodium, Wt% 2.3 1.9 2.4
Base Resin MI 60 60 60
Mpl~ C 88 86 85
Fpl, C 47 48.5 45
COMPRESSION MOLDING2
Tensile Break, psi 4350 4190 5330
Yield, psi 2880 3670 3590
Elongation, % 315 263 289
Flex Mod, K psi 53.2 76.4 88.3
Shore D hardness 66 67 68
' DSC second heat, 10°C/min heating rate.
Samples compression molded at 150°C annealed 24
hours at 60°C. 8422-2, 8422-3 were homogenized at
190°C before molding.
In comparing Surlyn° 8920 to Surlyn° 8422-2 and
Surlyn° 8422-3, it is noted that the high acid Surlyn°
8422-2 and 8422-3 ionomers have a higher tensile yield,
lower elongation, slightly higher Shore D hardness and much
higher flexural modulus. Surlyn° 8920 contains 15 weight
percent methacrylic acid and is 59% neutralized with
sodium.
In addition, Surlyn° SEP-503-1 (an experimental zinc
cation neutralized high acid methacrylic acid based ionomer
resin) and Surlyn° SEP-503-2 ( an experimental magnesium
cation neutralized high acid methacrylic acid based ionomer
resin) are high acid zinc and magnesium versions of the
Surlyn° AD 8422 high acid ionomers. When compared to the
CA 02288405 1999-11-10
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Surlyn° AD 8422 high acid ionomers, the Surlyn° SEP-503-1
and SEP-503-2 ionomers can be defined as follows:
TABLE 3
Surlvnm Ionomer Ion Melt Index Neutralization is
AD 8422-3 Na 1.0 45
SEP 503-1 Zn 0.8 38
SEP 503-2 Mg 1.8 43
Furthermore, Surlyn° 8162 is a zinc cation neutralized
methacrylic acid based high acid ionomer resin containing
approximately 20% by weight (i.e. 18.5-21.5% weight) _
methacrylic acid copolymer that has been 30-70%
neutralized. Surlyn° 8162 is currently commercially
available from DuPont.
For comparison purposes, examples of commercially
available low acid methaciylic acid based ionomer resins
are set forth below. These are many of the "hard" ionomers
utilized in the cover composition disclosed in U.S. Patent
No. 4,884,814. Along this line, the low acid ionomer resin
cover compositions disclosed in the '814 patent are
generally considered to be among the best prior art
methacrylic acid based cover compositions currently
available from Spalding & Evenflo Companies, Inc., the
assignee of the present application copending Canadian
Application No. 2,078,842.
CA 02288405 1999-11-10
18
TABLE
4
ASTM D 8 40 9910 8920
Cation Type Sodiun Zinc Sodiun
Helt flow index, D-1238 2.8 0.7 0.9
S gms/10 min
Specific Gravity, D-792 0.95 0.97 0.95
9/~'
Hardness, Share D-2240 66 64 66
0
Tensile Strength, D-638 (4.8) (3.b) (5.4)
1 0 (kpsi), HPa 33.1 24.8 37.2
Elongation, X 0-638 470 290 350
Flexural Hodulus, D-790 (51) (48) (55)
(kpsi) HPa 350 330 380
Tensile Impact (23C)D-18225 1020 1020 865
1 5 KJ/m, (ft.-lbs./in') (485) (485) (410)
Vicat Temperature, D-1525 b3 b2 58
C
X height Hethacrylic 15 15 15
acid (HAA)
X of Acid Groups 29 58 59
2 0 Cation Neutralized
ASTH D 8528 9970 9730
Cation Type Sodium Zinc Zinc
Helt floe index, D-1238 1.3 14.0 1.6
9ms/10 min
2 S Specific Gravity, 0-792 0.94 0.95 0.95
9/~'
Hardness, Shore 0-2240 60 62 63
D
Tensile Strength, D-638 (4.2) (3.2) (4.1)
(kpsi), HPa 29.0 22.0 28.0
3 0 Elongation, X 0-638 450 460 460
Flexural Hodulus, D-790 (32) (28) (30)
(kpsi) HPa 220 190 210
Tensile Impact (23C)D-18225 1160 760 1240
KJ/m, (ft.-lbs./in') (550) (360) (590)
3 5 Vicat Temperature, D-1525 73 b1 73
C
X Weight Hethacrylic 10 15 12
acid (HAA)
X of Acid Groups 54 22 38
Cation Neutralized
40 Examples of existing high id
ac acrylic
acid
based
ionomer resins include the Escor° or the Iotek acrylic acid
based high acid ionomers recently experimentally produced
CA 02288405 1999-11-10
19
by Exxon. In this regard, Escor°, or Iotek, 959 is a
sodium ion neutralized ethylene-acrylic acid copolymer and
Escor°, or Iotek;~ 960 is a zinc neutralized ethylene-
acrylic acid copolymer. According to Exxon, Ioteks'~959 and
960 contain from about 19.0 to about 21.0 % by weight
acrylic acid with approximately 30 to about 70 percent of
the acid groups neutralized with sodium and zinc ions
respectfully. The physical properties of these high acid
acrylic acid based ionomers are as follows:
TABLE 5
PROPERTY ESCORm (IOTEK) ESCORm (IOTEK)
959 960
Melt Index, g/10 min 2.0 1.8
Cation Sodium Zinc
Milting Point, F 172 174
Vicat Softening Point, F 130 131
Tensile ~ Break, psi 4600 3500
Elongation ~ Break, ~ 325 430
Hardness, Shore D 66 57
Flexural Modulus, psi 66,000 27,000
For comparison purposes, examples of commercially
available low acid acrylic acid based ionomer resins, such
as these utilized in U.S. Patent No. 4,911,451 are set
forth below.
CA 02288405 1999-11-10
20
TABLE
6
Typical Properties Low Acid (Iotek)Ionomers
of Escorm
Resin ASTM
Properties MethodUnits 40004010 80008020
Cation type zinczinc sodium
sodium
Melt index D-7.238g/10 2.5 1.5 0.8 1.6
min.
Density D-1505kg/m' 963 963 954 960
Melting Point D-3417C 90 90 90 87.5
Crystallization PointD-3417C 62 64 56 53
Vicat Softening PointD-1525C 62 63 61 64
% Weight Acrylic 16 -- 11 --
Acid
% of Acid Groups 30 -- 40 --
Cation Neutralized
Plaque ASTM
Properties MethodUnits 40004010 80008020
(3 mm thick,
compression molded)
Tensile at Break D-638 MPa 24 26 36 31.5
Yield point D-638 MPa nonenone 21 21
2 Elongation at break D-638 % 395 420 350 410
0
1% Secant modulus D-638 MPa 160 160 300 350
Shore Hardness D D-2240-- 55 55 61 58
Resin ASTM
Properties MethodUnits 80307010 70207030
Cation type sodium zinczinc
zinc
Melt index D-1238g/10 2.8 0.8 1.5 2.5
min.
Density D-1505kg/m' 960 960 960 960
Melting Point D-3417C 87.590 90 90
Crystallization PointD-3417C 55 -- -- --
3 Vicat Softening PointD-1525C 67 60 63 62.5
0
% Weight Acrylic -- -- -- --
Acid
% of Acid Groups -- -- -- --
Cation Neutralized
CA 02288405 1999-11-10
21
Plaque ASTM
Properties Method Units 8030 701070207030
(3 mm thick,
compression molded)
Tensile at Break D-638 MPa 28 38 38 38
Yield point D-638 MPa 23 nonenonenone
Elongation at break D-638 % 395 500 420 395
1% Secant modulus D-638 MPa 390 -- -- --
Shore Hardness D D-2240 -- 59 57 55 55
According to the present invention, it has been found
that when the above indicated new metal cation neutralized
acrylic acid based high acid ionomers, are processed
according to the parameters set forth below to produce the
covers of multi-layered golf balls, the resulting golf
balls will travel further than previously known low acid
ionomer resin covers and/or covers produced from high acid
ionomers and/or high acid/low acid ionomer blends due to
the balls' enhanced coefficient of restitution values.
This is particularly important in that an improvement of
.001 in C.O.R. generally relates to our improvement of
about 0.2 to 0.5 yards in travel distance. In addition,
the resulting golf balls maintain the playability and
durability characteristics exhibited by known low-acid
ionomer resin covered balls.
When blends of two of the above indicated metal cation
neutralized acrylic acid high acid ionomers are used (i.e.
"dibends"), the ratio of one type of metal cation
neutralized acrylic acid high acid ionomer to another is
generally from about 75% to about 25% and from about 25% to
about 75%. In addition, "triblends" can also be fornlulated
utilizing the new metal cation neutralized acrylic acid
based high acid ionomers of the present invention. The
general ratio for such "triblends" is 33.33%/33.33%/33.33%
by weight.
Additional compatible additive materials may also be
added to the compositions of the present invention, such as
CA 02288405 1999-11-10
22
dyes (for example, Ultramarine Blue sold by Whitaker,
Clark, and Daniels of South Painsfield, NJ), and pigments,
i.e. white pigments such as titanium dioxide (for example
Unitane 0-110) zinc oxide, and zinc sulfate, as well as
fluorescent pigments. As indicated in U.S. Patent
4,884,814, the amount of pigment and/or dye used in
conjunction with the polymeric cover composition depends on
the particular base ionomer mixture utilized and the
particular pigment and/or dye utilized. The concentration
of the pigment in the polymeric cover composition can be
from about 1% to about 10% as based on the weight of the
base ionomer mixture. A more preferred range is from about
1% to about 5% as based on the weight of the base ionomer
mixture. The most preferred range is from about 1% to
about 3% as based on the weight of the base ionomer
mixture. The most preferred pigment for use in accordance
with this invention is titanium dioxide.
Moreover, since these are various hues of white, i.e.
blue white, yellow white, etc., trace amounts of blue
pigment may be added to the cover stock composition to
impart a blue white appearance thereto. However, if
different hues of the color white are desired, different
pigments can be added to the cover composition at the
amounts necessary to produce the color desired.
In addition, it is within the purview of this
invention to add to the cover compositions of this
invention compatible materials which do not affect the
basic novel characteristics of the composition of this
invention. Among such materials are antioxidants (i.e.
Santonox R), antistatic agents, stabilizers and processing
aids. The cover compositions of the present inventiem may
also contain softening agents, such as plasticizers, etc.,
and reinforcing materials such as glass fibers and
inorganic fillers, as long as the desired properties
produced by the golf ball covers of the invention are not
impaired.
CA 02288405 1999-11-10
23
Furthermore, optical brighteners, such as those
disclosed in U.S. Patent No. 4,679,795, may also be
included in the cover composition of the invention.
Examples of suitable optical brighteners which can be used
in accordance with this invention are Uvitex OB as sold by
the Ciba-Geigy Chemical Company, Ardaley, N.Y. Uvitex OB is
thought to be 2,5-Bis(5-tert-butyl-2-benzoxazoly)thiopene.
Examples of other optical brighteners suitable for use in
accordance with this invention are as follows: Leucopure*
EGM as sold by Sandoz, East Hanover, N.J. 07936. Leucopure
EGM is thought to be 7-(2h-naphthol(1,2-d)-triazol-2y1)-
3phenyl-coumarin. Phorwhite K-2062 is sold by Mobay
Chemical Corporation, P.O. Box 385, Union Metro Park,
Union, N.J. 07083, and is thought to be a pyrazoline
derivative, Eastobrite OB-1 as sold by Eastman Chemical
Products, Inc. .Kingsport, Tenn., is thought to be 4,4-Bis(-
benzoxaczoly)stilbene. The above-mentioned Uvitex and
Eastobrite OB-1 are preferred optical brighteners for use
in accordance with this invention.
Moreover, since many optical brighteners are colored,
the percentage of optical brighteners utilized must not be
excessive in order to prevent the optical brightener from
functioning as a pigment or dye in its own right.
The percentage of optical brighteners which can be
used in accordance with this invention is from about 0.01%
to about 0.5% as based on the weight of the polymer used as
a cover stock. A more preferred range is from about 0.05%
to about 0.25 % with the most preferred range from about
0.10% to about .020% depending on the optical properties of
the particular optical brightener used and the polymeric
environment in which it is a part.
Generally, the additives are admixed with a ionomer to
be used in the cover composition to provide a masterbatch
(M.B.) of desired concentration and an amount of the
masterbatch sufficient to provide the desired amounts of
additive is then admixed with the copolymer blends.
CA 02288405 1999-11-10
24
The cover compositions of the present invention may be
produced according to conventional melt blending
procedures. In this regard, the above indicated high acid
ionomeric resins are blended along with the masterbatch
containing the desired additives in a Banbury type mixer,
two-roll mill, or extruded prior to molding. The blended
composition is then formed into slabs or pellets, etc. and
maintained in such a state until molding is desired.
Alternatively a simple dry blend of the pelletized or
granulated resins and color masterbatch may be prepared and
fed directly into the injection molding machine where
homogenization occurs in the mixing section of the barrel
prior to injection into the mold. If necessary, further
additives such as an inorganic filler, etc., may be added
and uniformly mixed before initiation of the molding
process.
Moreover, golf balls of the present invention can be
produced by molding processes currently well known in the
golf ball art. Specifically, the golf balls can be
produced by injection molding or compression molding the
novel cover compositions about wound or solid molded cores
to produce a golf ball having a diameter of about 1.680
inches or greater and weighing about 1.620 ounces. The
standards for both the diameter and weight of the balls are
established by the United States Golf Association
(U.S.G.A.). Although both solid core and wound cores can
be utilized in the present invention, as a result of their
lower cost and superior performance, solid molded cores are
preferred over wound cores.
Conventional solid cores are typically compression
molded from a slug of uncured or lightly cured elastomer
composition comprising a high cis content polybutadiene and
a metal salt of an a, a, ethylenically unsaturated
carboxylic acid such as zinc mono or diacrylate or
methacrylate. To achieve higher coefficients of
restitution in the core, the manufacturer may include a
CA 02288405 1999-11-10
small amount of a metal oxide such as zinc oxide. In
addition, larger amounts of metal oxide than those that are
needed to achieve the desired coefficient may be included
in order to increase the core weight so that the finished
5 ball more closely approaches the U.S.G.A. upper weight
limit of 1.620 ounces. Other materials may be used in the
core composition including compatible rubbers or ionomers,
and low molecular weight fatty acids such as stearic acid.
Free radical initiator catalysts such as peroxides are
10 admixed with the core composition so that on the
application of heat and pressure, a complex curing or
cross-linking reaction takes place.
The term "solid cores" as used herein refers not only
to one piece cores but also to those cores having a
15 separate solid layer beneath the cover and above the core
as in U.S. Patent No. 4,431,193, and other multilayer
and/or non-wound cores (such as those described in U.S.
Patent No. 4,848,770).
Wound cores are generally produced by winding a very
20 large elastic thread around a solid or liquid filled
balloon center. The elastic thread is wound around the
center to produce a finished core of about 1.4 to 1.6
inches in diameter, generally. Since the core material is
not an integral part of the present invention, a detailed
25 discussion concerning the specific types of core materials
which may be utilized with the cover compositions of the
invention are not specifically set forth herein. In this
regard, the cover compositions of the invention may be used
in conjunction with any standard golf ball core.
As indicated, the golf balls of the present invention
may be produced by forming covers consisting of the
compositions of the invention around cores by conventional
molding processes. For example, in compression molding,
the cover composition is formed via injection at about
380°F to about 450°F into smooth surfaced hemispherical
shells which are then positioned around the core in a
CA 02288405 1999-11-10
26
dimpled golf ball mold and subjected to compression molding
at 200-300°F for 2-10 minutes, followed by cooling at 50-
70°F for 2-10 minutes, to fuse the shells together to form
an unitary ball. In addition, the golf balls may be
produced by injection molding, wherein the cover
composition is injected directly around the core placed in
the center of a golf ball mold for a period of time at a
. mold temperature of from 50°F to about 100°F. After
molding the golf balls produced may undergo various further
finishing steps such as buffing, painting, and marking as
disclosed in U.S. Patent No. 4,911,451.
The present invention is further illustrated by the
following examples in which the parts of the specific
ingredients are by weight (pbw). It is to be understood
that the present invention is not limited to the examples,
and various changes and modifications may be made in the
invention without departing from the spirit and scope
thereof.
EXAMPLES
By blending the ingredients set forth in the Tables
below, a series of new metal cation neutralized high acid
ionomer resins and golf ball cover formulations containing
these resins were produced. Finished golf balls were
prepared using the cover compositions of the present
invention, controls and comparative cover compositions by
positioning a solid preformed cross-linked polybutadiene
core in an injection molding cavity in such a manner to
permit the uniform injection of the selected cover
composition over each core. Along this line, the cover
formulations were injection molded at about 400°F around
identical solid type cores having a finished diameter of
1.545 inches to produce golf balls approximately 1.680
inches in diameter having a normal cover thickness of
0.0675 inches. All materials were molded under essentially
identical conditions. The properties of coefficient of
CA 02288405 1999-11-10
27
restitution (C.O.R.) of the molded and finished balls,
Shore D hardness, cold crack resistance, spin rates, etc.
for the cover compositions were then determined.
In conducting the comparative prior art testing,
Escor° 4000/7030 and Escor° 900/8000 ionomers were
utilized. In this regard, blends of Escor° 4000/7030 and
Escor° 900/8000 (i.e. the subject of U.S. Patent No.
4,911,451) are considered by the inventors to be generally
among the best prior art cover compositions concerning
ethylene-acrylic acid ionomer (low acid) blends.
The data for each example represents the average data
for one dozen balls produced according to the desired
manner. The properties were measured according to the
following parameters:
Coefficient of restitution (C.O.R.) was measured by
firing the resulting golf ball in an air cannon at a
velocity of 125 feet per second against a steel plate which
is positioned 12 feet from the muzzle of the cannon. The
rebound velocity was then measured. The rebound velocity
was divided by the forward velocity to give the coefficient
of restitution.
Shore hardness was measured in accordance with ASTM
Test D-2240.
Cold cracking resistance was measured by firing balls
from an air cannon, 5 blows at 165 feet/sec, after the
balls had been conditioned for 24 hours at -10°F. After
allowing the balls to equilibrate to room temperature the
balls are inspected for cover cracking.
The spin rate of the golf ball was measured by
striking the resulting golf balls with a pitching wedge or
9-iron wherein the club-head speed is about 80 feet per
second and the ball is launched at an angle of 26 to 34
degrees with an initial velocity of about 110-115 feet per
second. The spin rate was measured by observing the
rotation of the ball in flight using stop action Strobe
photography.
CA 02288405 1999-11-10
28
EXAMPLE 1
Preparation of Acrylic Acid Based
High Acid Ionomera
A number of new cation neutralized acrylic acid based
high acid ionomer resins were prepared utilizing as the
copolymer of an olefin and an alpha, beta-unsaturated
carboxylic acid, a 20 weight percent acrylic acid/ethylene
copolymer produced by The Dow Chemical Company, Midland,
Michigan under the designation "Primacor 5981." According
to The Dow Chemical Company, Primacor 5981 has a melt index
(at 190°C, 2150 g) of 300 g/10 min. The carboxylic acid
groups present in the 20 weight percent acrylic
acid/ethylene copolymer were neutralized to various weight
percentages by a number of different metal cation salts
resulting in the production of several new thermoplastic
elastomers exhibiting enhanced properties for golf ball
cover production. Due to differences in the nature of the
cation salts, the amount of cation salts utilized, etc.,
the new high acid ionomer resins produced differed
substantially in the extent of neutralization and in melt
indices, as well as in resilience (i.e. C.O.R.) and
hardness values.
For the purpose of determining the weight percent of
neutralization of the carboxylic acid groups in the acrylic
acid/ethylene copolymer after reacting with various cation
salts, it was assumed that 1 mole of sodium (Na+),
potassium (K+), and lithium (Li+) neutralized one mole of
acrylic acid, and that one mole of zinc (Zn2+), magnesium
(Mg2+) , manganese (Mn2+) , calcium (Cap+) and nickel (Ni2+)
neutralized two moles of acrylic acid. The calculations of
neutralization were based upon an acrylic acid molecular
weight of 79 g/m, giving 0.2778 moles per 100 grams of
copolymer.
As indicated below in Table 7, the various cation
salts were added in variable amounts to the 20 weight
percent acrylic acid/ethylene copolymer in order to
CA 02288405 1999-11-10
29
determine the optimal level of neutralization for each of
the cations. In Table 7, NaOH refers to sodium hydroxide
(formula weight of 40). MnAc refers to manganese acetate
tetrahydrate having a formula weight of 245. LiOH is
lithium hydroxide, fwt=24. KOH is potassium hydroxide,
fwt=56. ZnAc is zinc acetate dihydrate, fwt=219.5. MgAc
is magnesium acetate tetrahydrate, fwt=214.4. CaAc is
calcium acetate, fwt=158. Mg0 is magnesium oxide,
fwt=40.3. NiAc is nickel acetate, fwt=176.8. All of these
cation salts are solids at room temperature.
The specific cation salts were added in differing
amounts with the 20 weight percent acrylic acid/ethylene
copolymer (i.e. the Primacor 5981) to an internal mixer
(Banbury*'type) for the neutralization reaction. The only
exception was calcium acetate, which, due to problems
encountered in solid form, was added as a 30 wt-% solution
in water.
In the neutralization reaction, the cation salts
solubilized in the Primacor 5981 acrylic acid/ethylene
copolymer above the melting point of the copolymer and a
vigorous reaction took place with a great deal of foaming
occurring as the cation reacted with the carboxylic acid
groups of the acrylic acid/ethylene copolymer and the
volatile by-products of water (in the case of oxides or
hydroxides) or acetic acid (when acetates are used) were
evaporated. The reaction was continued until foaming
ceased (i.e. about 30-45 minutes at 250-350°F), and the
batch was removed from the Banbury mixer. Mixing continued
of the batch obtained from the mixer on a hot two-roll mill
(175-250°F) to complete the neutralization reaction. The
extent of the reaction was monitored by measuring melt flow
index according to ASTM D-1238-E. As indicated below, the
neutralized products exhibited drastically different
properties depending upon the nature and amount of the
cation salts utilized.
* Trade-mark
CA 02288405 1999-11-10
TABLE 7
llt-X Wt-X Nelt Shore
FormulationCation NeutralizationIndex C.O.R.D
No. Salt Hardness
1(NaOH) 6.98 67.5 0.9 .804 71
2(NaOH) 5.66 54.0 2.4 .808 T3
5 3(N80H) 3.84 35.9 12.2 .812 b9
4(NaDH) 2.91 27.0 17.5 .812 (brittle)
5(Hnllc) 19.6 71.7 7.5 .809 73
6(NMc) 23.1 88.3 3.5 .814 T7
7(NMC) 15.3 53.0 7.5 .810 ~ 72
1 0 $(Hnllc) 26.5 106 0.7 .813 (brittle)
9(LiOH) 4.54 71.3 0.6 .810 74
10(l.iOH) 3.38 52.5 4.2 .818 72
11(LiOH) 2.34 35.9 18.6 .815 72
12(KOH) 5.30 36.0 19.3 Broke70
1 5 13(KOH) 8.26 57.9 7.18 .804 70
14(KOH) 10.7 77.0 4.3 .801 67
15(2Mc) 17.9 71.5 0.2 .806 71
16(ZMc) 13.9 53.0 0.9 .797 69
17(ZMc) 9.91 36.1 3.4 .793 67
2 0 18(NgAc) 17.4 T0.7 2.8 .814 74
19(HgAc) 20.6 87.1 1.5 .815 76
20(HgAc) 13.8 53.8 4.1 .814 74
21(CaAc) 13.2 69.2 1.1 .813 74
22(CaAc) 7.12 34.9 10.1 .808 70
2 S Controls: 50/50 Blend of loteks 8000/7030 C.O.R.=.810/65 Shore D Hardness
DuPont High Acid Surlyr~ 8422 (Na) C.O.R.=.811/70 Shore D Hardness
DuPOnt High Acid Surlyr~ 8162 (Zn) C.O.R.=.807/65 Shore 0 Hardness
Exxon High Acid Iotek EX-960 (Zn) C.O.R.=.796/65 Shore D Hardness
CA 02288405 1999-11-10
31
TABLE 7 (continued)
ut-x ut-x He(t
FormulationCation NeutralizationIndex C.O.R.
No. Salt
23(Hg0) 2.91 53.5 2.5 .813
24(Hg0) 3.85 71.5 2.8 .808
25(Hg0) 4.76 89.3 1.1 .809
[ 26(Hg0) 1.96 35.7 7.5 .815
Control for Formulations 23-26 is 50/50 lotek 8000/7030,
C.O.R.=.814, Formulation 26 C.O.R. uas normalized to that tontrol accordingly
TABLE 7 (continued)
i
1 0 Formulationut-X ut-X Helt C.O.R.
Ho. Cation NeutralizationIndex Shore
Salt D
Hardness
27(NiAc) 13.04 61.1 0.2 .802 71
28(NiAc) 10.71 48.9 0.5 .799 72
29(NiAc) 8.26 36.7 1.8 .796 69
30(NiAc) 5.66 24.4 7.5 .786 64
1 5 Control for Formulation Nos. 27-30 is 50/50 lotek 8000/7030, C.O.R.=.807
As indicated in Table 7, a number of the new cation
neutralized acrylic acid based high acid ionomer resins
exhibited C.O.R. and Shore D hardness values greater than
that exhibited by a 50/50 blend of the Iotek low acid
20 acrylic acid based hard ionomer resins, such as the Iotek
8000/7030 blend utilized in the cover compositions
disclosed in U.S. Patent No. 4,911,451. Moreover, included
in new acrylic acid based high acid ionomer resins were
numerous cation neutralized high acid ionomer resins
25 previously not available, such as those acrylic acid based
high acid ionomer resins neutralized to various degrees by
the manganese, lithium, potassium, magnesium, calcium and
nickel salts. Furthermore, the new cation neutralized
acrylic acid based high acid ionomers produced C.O.R. and
30 hardness values greater than those shown by the methacrylic
acid based high acid ionomer resins recently produced by
CA 02288405 1999-11-10
32
DuPont (i.e. Surlyn° 8422 (Na) and Surlyn° 8162 (Zn)) and
the acrylic acid based high acid resins experimentally
produced by Exxon (i.e. Iotek EX-959 and Ex-960 (Zn)),
collectively referred to as "the controls."
In addition, the results produced by Formulation Nos.
1 through 3 directed to the sodium ion neutralized
ethylene-acrylic acid copolymers and Formulation Nos. 15
through 17 directed to the zinc ion neutralized ethylene-
acrylic acid copolymers in comparison to the new Iotek high
acid ethylene acrylic acid ionomers were also of interest.
As indicated above, Escor° or Iotek Ex-959 is a sodium ion
neutralized ethylene-acrylic acid copolymer and Escor° or
Iotek Ex-960 is a zinc neutralized ethylene-acrylic acid
copolymer. According to Exxon, Ioteks 959 and 960 contain
from about 19.0 to about 21.0% by weight acrylic acid with
approximately 30 to about 70 percent of the acid groups
neutralized with sodium and zinc ions, respectfully.
Formulation No. 2 (i.e. 5.66 wt-% sodium salt, 54 wt-
neutralization, 2.4 melt index, .808 C.O.R. and 73 Shore D
hardness) is somewhat similar to Iotek 959 and Formulation
No. 16 (i.e. 13.9 wt-% zinc salt, 53 wt-% neutralization,
0.9 melt index, .797 C.O.R. and 69 Shore D hardness) is
somewhat similar to Iotek 960.
However, not only did the new cation neutralized
acrylic acid based high acid ionomers of the present
invention exhibit similar or better resilience (C.O.R.) at
comparable or better hardness values than those exhibited
by the sodium or zinc high acid Iotek ionomers, as a result
of the neutralization of the acrylic acid/ethylene
copolymer with several different cation salts, to a number
of different neutralization percentages, a wide variety of
new catior~ neutralized acrylic acid based high acid
ionomers were produced having improved resilience and
hardness values. These new cation neutralized high acid
ionomer resins are particularly valuable in the field of
golf ball production.
CA 02288405 1999-11-10
33
More particularly, the development of a number of
separate different cation neutralized high acid ionomers
besides the sodium or zinc high acid ionomers available
from DuPont or Exxon, such as the new manganese, lithium,
potassium, magnesium, calcium and nickel acrylic acid based
high acid ionomer resins, allows for the production of a
wide variety of cation neutralized high acid ionomer
blends. Furthermore, since the new sodium or zinc
neutralized high acid ionomers produced improved properties
over those produced by the existing available sodium or
zinc high acid ionomers, a number of new cover compositions
can be produced having enhanced characteristics.
Along this line, several of the cation neutralized
acrylic acid based high acid ionomer resins produced above
which exhibited enhanced C.O.R. and Shore D hardness values
were blended together and evaluated for the purpose of
determining whether any synergistic effects were produced
particularly with respect to enhanced C.O.R. values.
Specifically, from each group of the different cation
neutralized high acid ionomer resins set forth in Table 7,
the best overall ionomer (based upon C.O.R. , melt index and
Shore D hardness) was utilized to produce a number of
blends ("diblends" and "triblends") and processed to
produce the cover component of multi-layered golf balls.
The "diblends" consisted of 50/50 mixtures and the
"triblends" consisted of a 33.33/33.33/33.33 mixtures.
With respect to the blends set forth in Tables 8 and
9, Na refers to Formulation No. 3, C.O.R. (molded/finished)
of .812/817; Mn refers to Formulation No. 6, C.O.R.
(molded/finished) of .814/.814; Li refers to Formulation
No. 10, C.O.R. (molded/finished) of .818/.819; K refers to
Formulation No. 13, C.O.R. (molded/finished) of .805/.809;
Zn refers to Formulation No. 16, C.O.R. (molded/finished)
of .797/.796; Mg refers to Formulation No. 18, C.O.R.
(molded/finished) of .814/.820; Ca refers to Formulation
No. 21, C.O.R. (molded/finished) of .813/.812; Ni refers to
CA 02288405 1999-11-10
34
Formulation No. 28, C.O.R. (molded/finished) of .799/.817;
and 50/50 Iotek 8000/7030 refers to control of 50/50 blend
of Iotek 8000/7030, C.O.R. (molded/finished) of .810/.812.
The C.O.R. values of the "diblends" and "triblends"
were then evaluated after molding with a center stock
having the following composition:
HATERIAL t~EIGHT (ohr)
88-1220' 70.70
Taktene 220' 29.30
React Rite ZDA' 31.14
Zinc Oxide 6.7~
Zinc Steerete 20.15
Limestone 17.58
Ground Flash (20-40 20.15
mesh)
1 5 Blue Hasterbatch '012
Luperco 231XL' * .89
or T~igonox 29/40'
Papi 94' .50
'BR-1220 is high cis-polybutadiene from Shell Chemical Co., Houston Taxes.
2 0 'Taktene is high cis-polybutadiene from Polysar Chemical.
'ZOA is zinc diacrylate.
'Luperco 231XL is a peroxide-free radical initiator ma~factured and sold by
Atochem, Buffalo,
Neu York.
'Trigonox 29/40 is peroxide-free radical initiator manufactured and sold by
Akzo Chemie America,
2 5 Chicago, Illinois.
'Papi 94 is a polymeric diisocyanate available from Dou Chemical Co., Hidlend,
Hichigan.
In addition, the molded balls were coated and finished
according to the procedure mentioned above. The C.O.R.
values of the finished balls were determined in order to
30 evaluate whether any improvement in resilience was
produced. Generally, it is typical to observe a .002 to
.003 point pick up in C.O.R. values of the finished balls
in comparison to the molded balls . The results are set
forth in Tables SA, 8B and 9 below.
*Trade-mark
CA 02288405 1999-11-10
TABLE 8A
D_iblends (50/50 Blends) C.O.R.
(Molded/Finished) Values
Forwulation Blend C O R (Holded/Finished)
No.
5 31 Na/Hn .813/.818
32 Na/Li .813/.818
33 Na/K .809/.816
34 Na/Zn .811/.818
35 Na/Hg .813/.819
1 0 36 Na/Ca .811/.819
3T HNIi .811/.817
38 HNK .811/.818
39 HNZn .807/.814
40 HNH9 .809/.816
15 41 HNCa .809/.816
42 Li/K .810/.817
43 Li/Zn .813/.819
44 Li/Hg .812/.820
45 Li/Ca .811/.818
2 0 46 K/Zn .810/.815
47 K/H9 .811/.820
48 K/Ca .810/.817
49 ZNHg .807/.814
50 ZNCa .808/.814
2 5 st Hg/ca .8o1/.ats
52 Na/Ni .809/.815
53 HNNi .807/.814
54 Li/Ni .809/.816
55 K/Ni .809/.816
3 0 56 Zn/Ni .799/.804
57 Hg/Ni .805/.813
58 Ca/Ni .807/.815
59 Iotek .811/.818
959/960
60 Control .809/NA
3 S 61 Control .806/NA
Controls are Formulation No. 59, a 50/50 blend of Iotek 959/960; Formulation
No. 60 a 75/25 blend
of Surlyn 8162/8422; and Formulation No. 61 a 50/50 blind of lotek 8000/7030.
CA 02288405 1999-11-10
36
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CA 02288405 1999-11-10
36a
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CA 02288405 1999-11-10
37
In Table 8B above, the C.O. R. synergy values are based
upon the data from Table 7 of the various metal cation
neutralized high acid acrylic acid based ionomer resins and
the following calculations:
(COR)calc = coefficient calculated as weighted average
of as-molded COR's for polymers of salts 1 and 2
(COR) exp = experimental as-molded COR for blend
FINAL (COR)calc = coefficient calculated as weighted
average of finished COR's for polymers of salts
1 and 2
FINAL (COR) exp = experimental finished COR for blend
FINAL (COR) diff = difference between FINAL (COR) exp
and FINAL (COR) (calc)
As noted in Table 8B, positive synergy in resilience
is observed for nearly all of the finished (final) blends,
with substantial synergy being produced in Formulation Nos.
34, 38, 39, 43, 46, 48, 49, 50.
Moreover, the diblends were also evaluated against a
control Formulation No. 59 (see Table 8A), a 50/50 blend of
Iotek 959/960, the best available high acid blends, with
respect to improved C.O.R. values (i.e. 811/.818). Similar
or enhanced C.O.R. values (molded/finished) were observed
in Formulation Nos. 31 (Na/Mn), 32 (Na/Li), 34 (Na/Zn), 35
(Na/Mg), 36 (Na/Ca), 38 (Mn/K), 43 (Li/Zn), 44 (Li/Mg), 45
(Li/Ca), and 47 (K/Mg).
Furthermore, when reviewed for cold cracking, with the
exception of Formulation No. 35, all of the diblends tested
exhibited resistance to breaking. With respect to
Formulation No. 35, some breakage did occur with 2 out of
the 12 balls tested exhibiting breakage.
When the small test sample of the triblends were
evaluated (see Table 9 below) in comparison to a 50/50
blends of the low acid acrylic acid based hard ionomers
(i.e. Iotek 8000/7030 U.S. Patent No. 4,911,451), all of
the cation neutralized high acid acrylic acid based
CA 02288405 1999-11-10
38
triblends produced enhanced C.O.R. values upon molding and
finishing_ In addition, when subjected to cold cracking,
no breakages were observed.
TABLE 9
C.O.R.C.O.R.
FornulationCation !foldedFinished
Blend Ball
62 ZNIi/K .819 .828
Na/ZNLi .821 .829
i
64 lotek 8000/7030.816 .819
65 . Na/NNCa .820 .828
1 0 66 Na/K/Mn .821 .829
67 Na/K/N9 .821 .829
Consequently, not only are a number of new cation
neutralized acrylic acid based high acid ionomers now
available for golf ball cover construction, these new
cation neutralized acrylic acid based high acid ionomers
may be blended together in various combinations to produce
cover compositions exhibiting enhanced resilience (i.e.
distance) due to the synergies noted above.
EXAMPLE 2
In order to determine whether the diblends or
triblends of the new cation neutralized acrylic acid based
high acid ionomer resins produced different results when
dry blended ( i . a . prepared as simple dry blends of pre-made
single cation neutralized acrylic acid based high acid
ionomers, such as those set forth in Example 1 above) or
when produced as "in-situ" cation blends (i.e. the cations
were first blended and then added to the acrylic
acid/ethylene copolymers in the Banbury mixer) , a number of
comparison reactions were generated. Specifically, in-situ
Formulation Nos. 68-72 in Table 10 below correspond to dry-
blended Formulation Nos. 31, 32, 43, 44 and 46,
respectively, and in-situ Formulation Nos. 73 and 74 in
CA 02288405 1999-11-10
39
Table 10 below correspond to dry-blended Formulation Nos.
62 and 63, respectively.
TABLE 10
C.O.RC.O.R.Spin Shore
FormulationCation MoldedFinishedRate 0
No Blend 9-Iron.RPNHardness
.
b8 Na/Mn .822 .828 5,008 74
b9 Na/Li .820 .828 5,820 70
70 Li/Zn .820 .825 5,425 71
77 Li/Mg .821 .828 5,451 T3
T2 Zn/K .817 .821 5,934 69
1 0 73 Li/Zn/K .822 .826 5,266 71
74 Na/Li/Zn .821 .824 5,165 71
75 fotek .819 .824 5,926
959(Na)/960(Zn)
Tour Editionm 10,124
100
Tour Edition~ 9,821
90
1 5 Top-Flite~ 6,942
XL II
The results indicated that little difference in C.O.R.
was produced (relative to a control of 50/50 mixture of the
high acid Iotek 959/960) whether a dry blending process or
an in-situ blending process was used. Moreover, the data
20 further clearly indicated that the cation neutralized
acrylic acid based high acid ionomer blends of the present
invention generally exhibit higher C.O.R. values and
significantly lower spin rates than the best acrylic acid
based high acid ionomers (i.e. the Ioteks 959(Na)/960(Zn)
25 blend), see Formulation Nos. 68, 70, 71, 73 and 74 in
comparison to Formulation No. 75 (control). The lower
C.O.R. value and the substantially similar spin rate
produced by the Zn/K blend in Fornlulation 72 was attributed
to the slightly lower hardness of this blend versus the
30 others. As indicated in Table 7, the K and Zn acrylic acid
based high acid ionomers are a little softer than the Na,
Mn, Li and Mg acrylic acid based high acid ionomers.
Similarly, the higher spin rate of the Na/Li blend in
CA 02288405 1999-11-10
Formulation 69 was due to its relative softness versus the
other blends. In addition, other more subtle factors may
also be at play, such as differences in coefficient of
friction, deformation under load, etc., which have not
5 quantified.
In addition, when compared with a number of
commercially available balls produced by Spalding & Evenflo
Companies, Inc., the assignee of the present invention,
with low acid ionomer resin covers (i.e. the Tour Edition°
10 100, Tour Edition° 90 and Top-Flite° XL II balls) , the spin
rates of the cation neutralized acrylic acid high acid
ionomer blends of the present invention (i.e. Formulations
68-75) exhibited much lower spin rates. Consequently, the
cation neutralized acrylic acid based high acid ionomer
15 blends of the present invention produced, when utilized to
formulate the cover of a multi-layered golf ball, a much
harder surface then those produced by the low acid ionomer
covers presently available. This may be desirable to a
golfer who imparts unmanageable spin (slice/hook) to the
20 ball and thereofre may benefit from a "low spin" ball.
EXAMPhE 3
Acrylic Acid Based HicLh Acid Ionomer
Di Blends ContainincL Va rying Ratios of Cation Neutralized
Acrylic Acid Based High Acid Ionomers
25 In addition to the 50/50 blends of various
combinations of the new cation neutralized acrylic acid
based high acid ionomers set forth in Example 1, di-blends
varying from 25/75 to 75/25 ratios were produced utilizing
the more preferred diblends in the "in-situ" process
30 described in Example 2. In this regard, the more preferred
diblend formulations set forth in Example 1 (i.e.
Formulation No. 31 (Na/Mn), Formulation No. 32 (Na/Li),
Formulation 43 (Li/Zn), Formulation No. 44 (Li/Mg), and
Forn~ulation No. 46 (Zn/K)) were produced in-situ in 50/50,
CA 02288405 1999-11-10
41
25/75 and 75/25 combinations according to the following
formulations
TABLE 11
Formulations
IngredientsT6 77 78 79 80 81 82 83 84 85
Acid 100 100 100 100 100 100 100 100 100 100
'~
COpOlymler I
(Prinacor
5981)
1 0 NaOH 2.0 1.0 3.0 2.0 1.0 3.0 --- --- --- ---
Nn Acetate15.022.5 7.5 --- --- --- --- --- -" ---
lithium --- --- --- 3.1 4.T 1.6 3.1 1.6 4.T 3.1
Hydroxide
Monohydrate
1 5 Zinc ___ ___ ___ ___ ___ ___ 8.0012.04.0 ___
Acetate
Potassitm___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Hydroxide
Nagnesiun___ ___ ___ ___ ___ ___ ___ _._ ___ 10.5
2 0 Acetate
Ingredients Formulation
No.
86 87 88 89 90
Primacor 100 100 100 100 100
5981
lithium Hydroxide1.6 4.7 --- --- ---
Nagnesiun 15.8 5.3 --- --- ---
Acetate
2 5 Zinc Acetate--- --- 8.00 . 12.04.0
Potassium --- --- 4.50 2.25 6.75
Hydroxide
CA 02288405 1999-11-10
42
The di-blends produced the following C.O.R. values:
TABLE 12
FormulationCation Blend C.O.R. (Holded)
No.
76 50/50 Na/Mn .820
77 25/75 Na/Hn .821
7g 75/25 Na/Mn .825
79 50/50 Na/Li .822
gp 25/75 Na/Li .822
81 75/25 Na/Li .823
1 0 82 50/50 Li/Zn .816
83 25/75 Li/Zn
84 75/25 li/Zn .825
85 50/50 li/Hg .823
86 25/75 Li/Hg .822
1 S 87 75/25 li/Hg .821
88 50/50 ZNK .820
89 75/25 ZNK .798
90 25/75 ZNK .821
Control is a 50/50 Iotek LoW Acid Ionon~er Blend (8000/7030), C.O.R. (nalded)
.817
20 The results indicated that in general the new cation
neutralized acrylic acid based high acid ionomer diblends
produced enhanced C.O.R. values over the known acrylic acid
based low acid ionomer blends. See Formulation Nos. 76-81,
84-88 and 90. While Fortllulation 82 produced a lower C.O.R.
25 value than expected, the data suggested that in some cases,
a 50/50 blend is not optimal (particularly in the Zn/K and
the Li/Zn blends), while in others (i.e. Li/Mg, Na/Li) the
blend ratio is not significantly different.
EXAMPLE 4
30 Since the data set forth in Examples 1-3 indicated the
resilience (C.O.R.) and/or hardness properties of the cover
compositions can be substantially enhanced through the use
CA 02288405 1999-11-10
43
of the new cation neutralized acrylic acid based high acid
ionomers and/or diblends or triblends of such ionomers, the
molecular weight property of the acrylic acid/ethylene
copolymers utilized to produce the ionomers was evaluated.
Specifically, the molecular weight of the acid copolymers
was assessed for the purpose of determining whether further
enhanced properties can be produced by varying the
molecular weight of the acid copolymer.
In this regard, since the data indicated that there
was little difference between using the dry blending
process or the in-situ blending method for processing the
cations, the in-situ method of producing the cation
neutralized high acid ionomer blends was used in this
analysis.
Along this line, the diblend and triblends set forth
in Formulation Nos. 68, 73 and 74 are essentially the same
as those set forth below in Formulation Nos. 91, 94 and 97,
respectively. However, since a different batch of cores
was utilized than those used in Example 2, the C.O.R.'s are
slightly lower. While the cores utilized in the present
Example were of the same composition, the lower C.O.R. was
due to the age of the cores, i.e. molded cores will lose
C.O.R. upon aging mainly due to moisture pickup.
Formulation Nos. 92-93, 95-96 and 98-99, are similar to
those set forth in Formulation Nos. 91, 94 and 97,
respectively, with the exception that the molecular weight
of the acrylic acid/ethylene copolymer utilized was varied.
Specifically, Primacor 5983 and Primacor 5990 both contain
the same acid content as Primacor 5981 (i.e. 20 weight
percent acrylic acid) but have lower viscosities (lower
molecular weights) and lower densities. Primacor 5981 has
a melt index of 300 g/10 minute (ASTM Method D-1238 at 190°
C) and a Brookfield viscosity of 51,000 cps at 350° F.
Primacor 5983 has a melt index of 500 and a Brookfield
viscosity of 26,000 cps at 350° F; and Primacor 5990 has a
melt index of 1300 and viscosity of 13,000 cps at 350° F.
CA 02288405 1999-11-10
44
The resilience (C.O.R.) of the molded balls produced
utilizing the different molecular weight acrylic
acid/ethylene copolymers are set forth below in Table 13.
TABLE 13
S Formulation Cations Acid CopolymerC.O.R. (HOLDED)
No.
91 Na/Hn Primacor 5981.813
92 Na/Hn Primacor 5983.805
93 Na/Mn Primacor 5990Alt Balls
crack
94 Li/2n/K Primacor 5981.814
1~ 95 Li/ZNK Primacor 5983.809
96 Li/ZNK Primacor 5990All Balls
crack
97 Na/Li/Zn Primacor 5981.813
98 Na/Li/Zn Primacor 5983.808
99 Na/Li/Zn Primacor 5990All Balls
crack
15 The data indicated that a higher molecular weight acid
copolymer is preferred for obtaining high resilience (i.e.
C.O.R.) and required toughness.
The invention has been described with reference to the
preferred embodiment. Obviously, modifications and
20 alterations will occur to others upon a reading and
understanding of the preceding detailed description. It is
intended that the invention be construed as including all
such alterations and modifications insofar as they come
within the scope of the appended claims or the equivalents
25 thereof.
