U.S. patent application number 10/894853 was filed with the patent office on 2006-01-26 for golf ball.
This patent application is currently assigned to Callaway Golf Company. Invention is credited to Mark L. Binette, Thomas J. III Kennedy.
Application Number | 20060019771 10/894853 |
Document ID | / |
Family ID | 35657973 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060019771 |
Kind Code |
A1 |
Kennedy; Thomas J. III ; et
al. |
January 26, 2006 |
Golf ball
Abstract
An elastomeric composition for forming a golf ball or a
component thereof is disclosed that includes the use of a metal
thiosulfate, either alone or in combination with one or more
halogenated organic sulfur compounds, such as halogenated
thiophenol (HTP), or salts thereof. The composition produces a
molded product exhibiting an enhanced combination of increased
compression (i.e., softness) and/or resilience (C.O.R.).
Inventors: |
Kennedy; Thomas J. III;
(Wilbraham, MA) ; Binette; Mark L.; (Ludlow,
MA) |
Correspondence
Address: |
CALLAWAY GOLF C0MPANY
2180 RUTHERFORD ROAD
CARLSBAD
CA
92008-7328
US
|
Assignee: |
Callaway Golf Company
Carlsbad
CA
|
Family ID: |
35657973 |
Appl. No.: |
10/894853 |
Filed: |
July 20, 2004 |
Current U.S.
Class: |
473/351 |
Current CPC
Class: |
C08K 5/37 20130101; C08K
5/37 20130101; C08K 5/42 20130101; C08L 9/00 20130101; C08L 9/00
20130101; C08L 9/00 20130101; C08K 5/098 20130101; C08K 5/098
20130101; A63B 37/0003 20130101; C08K 5/42 20130101; A63B 37/0061
20130101; A63B 37/0064 20130101 |
Class at
Publication: |
473/351 |
International
Class: |
A63B 37/00 20060101
A63B037/00 |
Claims
1-12. (canceled)
13. A composition for forming a golf ball or a golf ball component,
said composition comprising a base elastomer selected from
polybutadiene and mixtures of polybutadiene with other elastomers,
said polybutadiene having a weight average molecular weight of from
about 50,000 to about 500,000, at least one metallic salt of an
.alpha.,.beta.-ethylenically unsaturated monocarboxylic acid, a
free radical initiator, a halogenated thiophenol in an amount of
0.1 to 2.0 parts by weight of halogenated thiophenol based on 100
parts by weight elastomer, and a sodium hexamethylene thiosulfate
in an amount of about 0.25 to about 2.0 parts by weight of the
sodium hexamethylene thiosulfate based on 100 parts by weight
elastomer.
14. The composition as defined in claim 13, wherein said sodium
hexamethylene thiosulfate is disodium
hexamethylene-1,6-bisthiosulfate dihydrate.
15. The composition as defined in claim 13, wherein said
halogenated thiophenol is a chlorothiophenol or a salt thereof.
16. The composition as defined in claim 14, wherein said
halogenated thiophenol is pentachlorothiophenol, or a salt
thereof.
17. The composition as defined by claim 1, further comprising a
modifying ingredient selected from fillers, fatty acids, metal
salts of fatty acids, metal oxides, and mixtures thereof.
18-20. (canceled)
21. The composition as defined in claim 13, wherein said
composition comprises from about 0.5 to about 1.5 parts by weight
of the sodium hexamethylene thiosulfate based on 100 parts by
weight elastomer.
22. The composition as defined in claim 13, wherein the halogenated
thiophenol is zinc pentachlorothiophenol.
23-26. (canceled)
27. A golf ball comprising: a core formed from a composition
comprising a polybutadiene material, zinc oxide, zinc stearate, at
least one metallic salt of an .alpha.,.beta.-ethylenically
unsaturated monocarboxylic acid in an amount of 15 to 50 parts by
weight per 100 parts by weight of the polybutadiene material, a
free radical initiator in an amount of 0.1 to 10 parts by weight
per 100 parts by weight of the polybutadiene material, a
halogenated thiophenol in an amount of 0.1 to 2.0 parts by weight
per 100 parts by weight of the polybutadiene material, and a sodium
hexamethylene thiosulfate in an amount of 0.25 to 2.0 parts by
weight per 100 parts by weight of the polybutadiene material,
wherein the core has a diameter ranging from 1.0 inch to 1.6 inches
and a coefficient of restitution greater than 0.780; and a cover
disposed over the core.
28. The golf ball according to claim 27 further comprising at least
one boundary layer between the core and the cover.
29. The golf ball according to claim 27 wherein the polybutadiene
material comprises a first polybutadiene having a first Mooney
viscosity value and a second polybutadiene having a second Mooney
viscosity value wherein the first Mooney viscosity value is greater
than the second Mooney viscosity value.
30. The golf ball according to claim 27 wherein sodium
hexamethylene thiosulfate is disodium
hexamethylene-1,6-bisthiosulfate dihydrate.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of golf ball
construction and, more particularly, to elastomeric compositions
for producing golf balls or molded components thereof. The improved
golf balls exhibit enhanced combinations of compression and/or
resilience properties. Methods of preparing such golf balls are
also disclosed herein.
BACKGROUND OF THE INVENTION
[0002] Golf balls have traditionally been categorized in three
different groups. These are, namely, one-piece or unitary balls,
wound balls, and multi-piece solid balls.
[0003] A one-piece ball typically is formed from a solid mass of
moldable material which has been cured to develop the necessary
degree of hardness. The one-piece ball generally possesses no
significant difference in composition between the interior and
exterior of the ball. These balls do not have an enclosing cover.
One piece balls are described, for example, in U.S. Pat. No.
3,313,545; U.S. Pat. No. 3,373,123; and U.S. Pat. No.
3,384,612.
[0004] A wound ball has frequently been referred to as a "three
piece ball" since it is produced by winding vulcanized rubber
thread under tension around a solid or semi-solid center to form a
wound core and thereafter enclosed in a single or multi-layer
covering of tough protective material. For many years the wound
ball was desired by many skilled, low handicap golfers.
[0005] In this regard, the three piece wound ball typically has a
balata, or balata like, cover which is relatively soft and
flexible. Upon impact, it compresses against the surface of the
club producing high spin. Consequently, the soft and flexible
balata covers along with wound cores provide an experienced golfer
with the ability to apply a spin to control the ball in flight in
order to produce a draw or a fade or a backspin which causes the
ball to "bite" or stop abruptly on contact with the green.
Moreover, the balata cover produces a soft "feel" to the low
handicap player. Such playability properties of workability, feel,
etc., are particularly important in short iron play and low swing
speeds and are exploited significantly by highly skilled
players.
[0006] However, a three-piece wound ball has several disadvantages.
For example, a thread wound ball is relatively difficult to
manufacture due to the number of production steps required and the
careful control which must be exercised in each stage of
manufacture to achieve suitable roundness, velocity, rebound,
"click", "feel", and the like.
[0007] Additionally, a soft thread wound (three-piece) ball is not
well suited for use by the less skilled and/or high handicap golfer
who cannot intentionally control the spin of the ball. For example,
the unintentional application of side spin by a less skilled golfer
produces hooking or slicing. The side spin reduces the golfer's
control over the ball as well as reduces travel distance.
[0008] Similarly, despite all of the benefits of balata, balata
covered balls are easily "cut" and/or damaged if mishit.
Consequently, golf balls produced with balata or balata containing
cover compositions can exhibit a relatively short life span. As a
result of this negative property, balata and its synthetic
substitute, trans-polyisoprene, and resin blends, have been
essentially replaced as the cover materials of choice by golf ball
manufacturers by materials comprising ionomeric resins and other
elastomers such as polyurethanes.
[0009] Multi-piece solid golf balls, on the other hand, include a
solid resilient core and a cover having single or multiple layers
employing different types of material molded on the core. The core
can also include one or more layers. Additionally, one or more
intermediate layers can also be included between the core and cover
layers.
[0010] By utilizing different types of materials and different
construction combinations, multi-piece solid golf balls have now
been designed to match and/or surpass the beneficial properties
produced by three-piece wound balls. Additionally, the multi-piece
solid golf balls do not possess the manufacturing difficulties,
etc., that are associated with the three-piece wound balls.
[0011] The one-piece golf ball and the solid core for a multi-piece
solid (non-wound) ball frequently are formed from a combination of
elastomeric materials such as polybutadiene and other rubbers that
are cross-linked. These materials are molded under high pressure
and temperature to provide a ball or core of suitable hardness and
resilience. The cover or cover layers typically contain a
substantial quantity of ionomeric resins that impart toughness and
cut resistance to the covers. Additional cover materials include
synthetic balatas, polyurethanes, and blends of ionomers with
polyurethanes, etc.
[0012] As a result, a wide variety of multi-piece solid golf balls
are now available to suit an individual player's game. In essence,
different types of balls have been, and are being, specifically
designed or "tailor made" to suit various skill levels. Moreover,
improved golf balls are continually being produced by golf ball
manufacturers with technological advancements in materials and
manufacturing processes.
[0013] In this regard, the elastomeric composition of the core or
center of a golf ball is important in that it affects several
characteristics (i.e., playability, durability, etc.) of the ball.
Additionally, the elastomeric composition provides resilience to
the golf ball, while also providing many desirable properties to
both the core and the overall golf ball, including weight,
compression, etc.
[0014] Due to the continuous importance of improving the properties
of a golf ball, it would be beneficial to form an elastomeric
composition that exhibits improved properties, particularly
improved combinations of compression and/or resilience, over known
compositions. This is one of the objectives of the present
invention disclosed below.
[0015] These and other non-limiting objects and features of the
invention will be apparent from the following summary and
description of the invention, and from the claims.
SUMMARY OF THE INVENTION
[0016] The present invention satisfies the noted general objectives
and provides, in one aspect, a polybutadiene rubber composition for
producing a golf ball or a molded component thereof. The resulting
golf ball or golf ball component exhibits enhanced compression
and/or resilience. Methods for producing such a golf ball or golf
ball component are also included herein.
[0017] And in yet another aspect, the present invention provides a
golf ball comprising a core component formed from a cured,
polybutadiene rubber composition. One or more metal thiosulfates,
such as hexamethylene thiosulfates, are included in the composition
to increase the compression and/or resilience (i.e., C.O.R.) of the
resulting molded product. The golf ball further comprises one or
more core, intermediate or cover layers disposed over the core
component.
[0018] In a further aspect, the present development provides a golf
ball comprising a spherical molded rubber component formed from a
polybutadiene, a mixture of polybutadienes or a mixture of
polybutadiene with one or more other elastomers, and one or more
curing agents. The curing agents include metallic salts of
unsaturated carboxylic acid and a crosslinking initiator such as
organic peroxide. The curing agents are blended into the
polybutadiene rubber to crosslink the molecules main chain, etc.
Also included in the composition is a hexamethylene thiosulfate,
including a sodium hexamethylene thiosulfate, such as disodium
hexamethylene (HTS or DHTS). This combination of materials
produces, when molded, golf balls exhibiting improved combinations
of characteristics, such as increased compression and/or
resilience.
[0019] In an additional aspect, the development disclosed herein
concerns a composition for forming a molded golf ball or a golf
ball component such as a molded core. The composition comprises a
base elastomer selected from polybutadiene, mixtures of
polybutadiene or mixtures of polybutadiene and other elastomers,
curing agents such as a metallic salt of an unsaturated carboxylic
acid and a crosslinking initiator such as an organic peroxide, and
a disodium hexamethylene thiosulfate (DHTS). Preferably, the
polybutadiene has a weight average molecular weight of about 50,000
to about 1,000,000 and the disodium hexamethylene thiosulfate is
hexamethylene-1,6-bis(thiosulfate), disodium salt, dihydrate. The
composition can also include one or more modifying ingredients
selected from the group consisting of fillers, fatty acids,
peptizers, metal oxides, and mixtures thereof.
[0020] In a yet further aspect, the development relates to the
addition of one or more halogenated organic sulfur compounds and/or
one or more hexamethylene thiosulfates to a polybutadiene rubber
composition in order to increase the combination of compression
(i.e., softness) and/or resilience (i.e., speed) of the molded
product. The preferred halogenated organic sulfur compounds include
halogenated thiophenols such as fluoro-, chloro-, bromo-, and
iodo-thiophenols, and metallic salts thereof. More preferably, the
halogenated thiophenol is a chlorophenol such as
pentachlorothiophenol (PCTP) and salts thereof, such as zinc
pentachlorothiophenol (ZnPCTP). The preferred hexamethylene
thiosulfates include, but are not limited to, sodium hexamethylene
thiosulfates, such as disodium hexamethylene-1,6-bisthiosulfate,
dihydrate (DHTS). The combination of the hexamethylene thiosulfate
and the halogenated thiophenol produces synergistic effects which
results in enhanced compression and/or resilience in the molded
product over known compositions.
[0021] In another aspect, it has been noted that the sodium
hexamethylene thiosulfate, such as disodium
hexamethylene-1,6-bisthiosulfate, dihydrate (DHTS), and an
optionally halogenated organic sulfur compound can be utilized in
combination with lower solution viscosity and/or lower linearity
(more branched) polybutadiene materials and crosslinking agents to
produce similar compression (i.e., softness) and/or resilience
characteristics produced by components molded from high solution
viscosity/high linearity polymer polybutadienes. This allows for
the interchangeability of these materials for certain usages in
golf ball construction.
[0022] In a yet further aspect, the present invention concerns
improved polybutadiene compositions suitable for use in golf ball
construction. The composition comprises a base elastomer selected
from polybutadiene and/or mixtures of polybutadiene with other
elastomers, said polybutadiene having a weight average molecular
weight of from about 50,000 to about 500,000, and a Mooney
viscosity of from about 20 to about 100, at least one metallic salt
of an .varies., .beta.-ethylenically unsaturated monocarboxylic
acid, a free radical initiator, and at least one halogenated
organic sulfur compound and/or at least one disodium hexamethylene
thiosulfate. The composition further comprises one or more
modifying ingredients selected from the group consisting of
additional curing agents or aids, such as activators, retardants
and accelerators, processing additives such as oils and resins,
coupling agents, and plasticizers, fillers, pigments, fatty acids,
metal oxides, waxes, antioxidants, reinforcing materials and
secondary peptizing agents, and mixtures thereof.
[0023] Preferably, in this aspect, the disodium hexamethylene
thiosulfate (DHTS) is hexamethylene-1,6-bisthiosulfate, disodium
salt, dihydrate and the halogenated organic sulfur compound is a
halogenated thiophenol such as fluoro-, chloro-, bromo-, and
iodo-thiophenol. More preferably, the halogenated thiophenol is
pentachlorothiophenol (PCTP) and salts thereof. The amount of
hexamethylene thiosulfate is preferably from about 0.1 to about 3.0
parts per hundred elastomer or resin (phr), more preferably from
about 0.5 to about 2.0 phr, and most preferably from about 0.5 to
about 1.5 phr. The amount of halogenated thiophenol is preferably
from about 0.01 to about 5.0 phr, more preferably from about 0.10
to about 2.0 phr, and most preferably from about 0.5 to about 1.0
phr.
[0024] Further scope of the applicability of the present invention
will become apparent from the detailed description given hereafter.
It should, however, 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 scope of the
invention will become apparent to those skilled in the art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] The present invention relates to improved elastomeric
compositions for producing a golf ball or to a molded golf ball
component thereof, such as a molded core or center component
utilized in golf ball construction.
[0026] It has been ascertained that the addition of a hexamethylene
thiosulfate and an optional organic sulfur compound, such as an
organic thiophenol, to polybutadiene based elastomers produces
molded golf ball components and/or golf ball products incorporating
the same which exhibit enhanced combinations of compression and/or
resilience.
[0027] The compositions of the present invention comprise a
polybutadiene-based elastomer selected from the group consisting of
polybutadienes, mixtures thereof or mixtures of the polybutadienes
with other elastomers, one or more crosslinking agents and a metal
thiosulfate, such as disodium hexamethylene thiosulfate (DHTS).
Also optionally included in the compositions are one or more
modifying ingredients such as additional curing agents or aids,
processing additives, secondary peptizers, fillers, reinforcing
agents, fatty acids, metal oxides, etc. The polybutadiene
preferably has a weight average molecular weight of about 50,000 to
about 1,000,000, including from about 50,000 to about 500,000, and
a Mooney viscosity of from about 20 to about 100. The disodium
hexamethylene thiosulfate (DHTS) is preferably
hexamethylene-1,6-bis(thiosulfate), disodium salt, dihydrate. It
has been found that the addition of the disodium hexamethylene
thiosulfate (DHTS) to the polybutadiene compositions enhances the
compression and/or resilience of the molded products.
[0028] In a further embodiment, the present invention relates to
the use of a metal thiosulfate, such as disodium hexamethylene
thiosulfates (DHTS), either alone or in combination with one or
more halogenated organic sulfur compounds, including halogenated
thiophenols, to enhance the combination of softness and/or
resilience of polybutadiene based core compositions. Such
polybutadiene based core compositions preferably comprise a base
elastomer selected from polybutadiene and/or mixtures of
polybutadiene with other elastomers and co-curing agents such as a
metallic salt of unsaturated carboxylic acid and a free radical
initiator. The core composition can further comprise one or more
modifying agents selected from fillers, fatty acids, metal oxides,
moldabilty additives, processing aids, dispersing agents, and
mixtures thereof. Preferably, the disodium hexamethylene
thiosulfate (DHTS) is hexamethylene-1,6-bis(thiosulfate), disodium
salt, dihydrate, and the halogenated thiophenol is a fluoro-,
chloro-, bromo-, or iodo-thiophenol, or a metal salt thereof. The
metal salt can include zinc, calcium, potassium, magnesium, sodium,
and lithium salts. More preferably, the halogenated thiophenol is
pentachlorothiophenol (PCTP) and/or the metal salt, zinc
pentachlorothiophenol (ZnPCTP).
[0029] In an additional embodiment, it has been noted that the
disodium hexamethylene thiosulfate (DHTS) and optionally a
halogenated thiophenol, can be utilized in combination with lower
solution viscosity/lower linearity polybutadiene materials to
produce similar compressions (softness) and/or resilience (C.O.R.)
characteristics produced by components molded from high solution
viscosity/high linearity polymer polybutadienes (polybutadienes may
have the same Mooney viscosity and different solution viscosities
due to the higher linearity of the polymer). This allows for lower
solution viscosity/lower linearity materials to be used somewhat
interchangeably in certain usages for golf ball construction. This
is both a cost and processing advantage in that the high
solution/high linearity polymers are more expensive to make and do
not process as well due to their "sticky" nature.
[0030] The golf balls including the compositions of the present
invention can be one-piece, two-piece, or multi-layer balls.
Non-limiting examples of golf balls according to the present
invention include a one-piece ball comprising polybutadiene rubber.
Alternatively, a two-piece ball can be formed with a core formed
from a core composition including polybutadiene rubber of the
present invention and a cover disposed about the core. A
multi-piece ball can also be formed with a core formed from a core
composition including a polybutadiene rubber, a mantle or
intermediate layer, and a cover disposed about the mantle. A
multi-layer ball can also be formed wherein the ball includes a
multi-layer core, where one or more layers of the multi-layer core
is formed from a core composition including polybutadiene rubber in
accordance with the present invention. Additionally, the
compositions of this development can also be utilized to produce
the inner center or molded core of a three-piece or wound ball.
[0031] In this regard, the construction of unitary golf balls or
golf balls with molded polybutadiene cores or other components with
higher resilience, while having substantially the same or lower
compression, i.e., softness, is in many instances desired. When the
construction of a molded core is desired, the diameter of the core
is determined based upon the desired ball diameter minus the
thickness of the cover layer(s) or intermediate layer(s) (if
desired). The core generally has a diameter of about 1.0 to 1.6
inches, preferably about 1.40 to 1.60 inches, and more preferably
from about 1.470 to about 1.585 inches. Additionally, the weight of
the core is adjusted so that the finished golf ball closely
approaches the U.S.G.A. upper weight limit of 1.620 ounces. The
molded core exhibits a resilience (C.O.R.) of greater than 0.760,
preferably greater than 0.780, and more preferably greater than
0.800, and a compression (Instron) of greater than 0.0880,
preferably greater than 0.0900, and more preferably greater than
0.0950. Optimal combinations of core compression and resilience are
further exhibited by this development.
[0032] A detailed description of the various components and
materials utilized in the present invention golf balls and/or
components thereof is set forth in more detail below after a
description of various golf ball properties and characteristics
utilized herein.
Properties and Characteristics
[0033] Two principal properties involved in golf ball performance
are resilience and compression. Resilience is determined by the
coefficient of restitution (C.O.R.), i.e., the constant "e" which
is the ratio of the relative velocity of an elastic sphere after
direct impact to that before impact. As a result, the coefficient
of restitution ("e") can vary from 0 to 1, with 1 being equivalent
to a perfectly or completely elastic collision and 0 being
equivalent to a perfectly or completely inelastic collision.
[0034] Resilience (C.O.R.), along with additional factors such as
club head speed, angle of trajectory and ball configuration (i.e.,
dimple pattern) generally determine the distance a ball will travel
when hit. Since club head speed and the angle of trajectory are
factors not easily controllable by a manufacturer, factors of
concern among manufacturers are the coefficient of restitution
(C.O.R.) and the surface configuration of the ball.
[0035] The coefficient of restitution (C.O.R.) in solid core balls
is a function of the composition of the molded core and of the
cover. In balls containing a wound core (i.e., balls comprising a
liquid or solid center, elastic windings, and a cover), the
coefficient of restitution is a function of not only the
composition of the center and the cover, but also the composition
and tension of the elastomeric windings.
[0036] The coefficient of restitution is the ratio of the outgoing
velocity to the incoming velocity. In the examples of this
application, the coefficient of restitution of a golf ball was
measured by propelling a ball horizontally at a speed of 125.+-.1
feet per second (fps) against a generally vertical, hard, flat
steel plate and measuring the ball's incoming and outgoing velocity
electronically. Speeds were measured with a pair of Ohler Mark 55
ballistic screens, which provide a timing pulse when an object
passes through them. The screens are separated by 36 inches and are
located 25.25 inches and 61.25 inches from the rebound wall. The
ball speed was measured by timing the pulses from screen 1 to
screen 2 on the way into the rebound wall (as the average speed of
the ball over 36 inches), and then the exit speed was timed from
screen 2 to screen 1 over the same distance. The rebound wall was
tilted 2 degrees from a vertical plane to allow the ball to rebound
slightly downward in order to miss the edge of the cannon that
fired it.
[0037] As indicated above, the incoming speed should be 125.+-.1
fps. Furthermore, the correlation between C.O.R. and forward or
incoming speed has been studied and a correction has been made over
the .+-.1 fps range so that the C.O.R. is reported as if the ball
had an incoming speed of exactly 125.0 fps.
[0038] The coefficient of restitution must be carefully controlled
in all commercial golf balls if the ball is to be within the
specifications regulated by the United States Golf Association
(U.S.G.A.). Along this line, the U.S.G.A. standards indicate that a
"regulation" ball cannot have an initial velocity (i.e., the speed
off the club) exceeding 255 feet per second in an atmosphere of
75.degree. F. when tested on a U.S.G.A. machine. Since the
coefficient of restitution of a ball is related to the ball's
initial velocity, it is highly desirable to produce a ball having
sufficiently high coefficient of restitution to closely approach
the U.S.G.A. limit on initial velocity, while having an ample
degree of softness (i.e., hardness) to produce enhanced playability
(i.e., spin, etc.).
[0039] As indicated above, compression is another important
property involved in the performance of a golf ball. The
compression of the ball can affect the playability of the ball on
striking and the sound or "click" produced. Similarly, compression
can affect the "feel" of the ball (i.e., hard or soft responsive
feel), particularly in chipping and putting.
[0040] Moreover, while compression itself has little bearing on the
distance performance of a ball, compression can affect the
playability of the ball on striking. The degree of compression of a
ball against the club face and the softness of the cover strongly
influence the resultant spin rate. Typically, a softer cover will
produce a higher spin rate than a harder cover. Additionally, a
harder core will produce a higher spin rate than a softer core.
This is because at impact a hard core serves to compress the cover
of the ball against the face of the club to a much greater degree
than a soft core thereby resulting in more "grab" of the ball on
the clubface and subsequent higher spin rates. In effect, the cover
is squeezed between the relatively incompressible core and
clubhead. When a softer core is used, the cover is under much less
compressive stress than when a harder core is used and therefore
does not contact the clubface as intimately. This results in lower
spin rates.
[0041] The term "compression" utilized in the golf ball trade
generally defines the overall deflection that a golf ball undergoes
when subjected to a compressive load. For example, compression
indicates the amount of change in golf ball's shape upon striking.
The development of solid core technology in two-piece or
multi-piece solid balls has allowed for much more precise control
of compression in comparison to thread wound three-piece balls.
This is because in the manufacture of solid core balls, the amount
of deflection or deformation is precisely controlled by the
chemical formula used in making the cores. This differs from wound
three-piece balls wherein compression is controlled in part by the
winding process of the elastic thread. Thus, two-piece and
multi-layer solid core balls exhibit much more consistent
compression readings than balls having wound cores such as the
thread wound three-piece balls.
[0042] In the past, PGA compression related to a scale of from 0 to
200 given to a golf ball. The lower PGA compression value, the
softer the feel of the ball upon striking. In practice, tournament
quality balls have compression ratings around 40 to 110, and
preferably around 50 to 100.
[0043] In determining PGA compression using the 0 to 200 scale, a
standard force is applied to the external surface of the ball. A
ball which exhibits no deflection (0.0 inches in deflection) is
rated 200 and a ball which deflects 2/10.sup.th of an inch (0.2
inches) is rated 0. Every change of 0.001 of an inch in deflection
represents a 1 point drop in compression. Consequently, a ball
which deflects 0.1 inches (100.times.0.001 inches) has a PGA
compression value of 100 (i.e., 200 to 100) and a ball which
deflects 0.110 inches (110.times.0.001 inches) has a PGA
compression of 90 (i.e., 200 to 110).
[0044] In order to assist in the determination of compression,
several devices have been employed by the industry. For example,
PGA compression is determined by an apparatus fashioned in the form
of a small press with an upper and lower anvil. The upper anvil is
at rest against a 200-pound die spring, and the lower anvil is
movable through 0.300 inches by means of a crank mechanism. In its
open position, the gap between the anvils is 1.780 inches, allowing
a clearance of 0.200 inches for insertion of the ball. As the lower
anvil is raised by the crank, it compresses the ball against the
upper anvil, such compression occurring during the last 0.200
inches of stroke of the lower anvil, the ball then loading the
upper anvil which in turn loads the spring. The equilibrium point
of the upper anvil is measured by a dial micrometer if the anvil is
deflected by the ball more than 0.100 inches (less deflection is
simply regarded as zero compression) and the reading on the
micrometer dial is referred to as the compression of the ball. In
practice, tournament quality balls have compression ratings around
80 to 100 which means that the upper anvil was deflected a total of
0.120 to 0.100 inches. When golf ball components (i.e., centers,
cores, mantled core, etc.) smaller than 1.680 inches in diameter
are utilized, metallic shims are included to produce the combined
diameter of the shims and the component to be 1.680 inches.
[0045] An example to determine PGA compression can be shown by
utilizing a golf ball compression tester produced by OK Automation,
Sinking Spring, Pa. (formerly, Atti Engineering Corporation of
Newark, N.J.). The compression tester produced by OK Automation is
calibrated against a calibration spring provided by the
manufacturer. The value obtained by this tester relates to an
arbitrary value expressed by a number which may range from 0 to
100, although a value of 200 can be measured as indicated by two
revolutions of the dial indicator on the apparatus. The value
obtained defines the deflection that a golf ball undergoes when
subjected to compressive loading. The Atti test apparatus consists
of a lower movable platform and an upper movable spring-loaded
anvil. The dial indicator is mounted such that is measures the
upward movement of the spring-loaded anvil. The golf ball to be
tested is placed in the lower platform, which is then raised a
fixed distance. The upper portion of the golf ball comes in contact
with and exerts a pressure on the spring-loaded anvil. Depending
upon the distance of the golf ball to be compressed, the upper
anvil is forced upward against the spring.
[0046] Alternative devices have also been employed to determine
compression. For example, Applicant also utilizes a modified Riehle
Compression Machine originally produced by Riehle Bros. Testing
Machine Company, Philadelphia, Pa., to evaluate compression of the
various components (i.e., cores, mantle cover balls, finished
balls, etc.) of the golf balls. The Riehle compression device
determines deformation in thousandths of an inch under a load
designed to emulate the 200 pound spring constant of the Atti or
PGA compression testers. Using such a device, a Riehle compression
of 61 corresponds to a deflection under load of 0.061 inches.
[0047] Furthermore, additional compression devices may also be
utilized to monitor golf ball compression. These devices have been
designed, such as a Whitney Tester, Whitney Systems, Inc.,
Chelsford, Mass., or an Instron Device, Instron Corporation,
Canton, Mass., to correlate or correspond to PGA or Afti
compression through a set relationship or formula.
[0048] As used herein, "Shore D hardness" of a cover is measured
generally in accordance with ASTM D-2240, except the measurements
are made on the curved surface of a molded cover, rather than on a
plaque. Furthermore, the Shore D hardness of the cover is measured
while the cover remains over the core. When a hardness measurement
is made on a dimpled cover, Shore D hardness is measured at a land
area of the dimpled cover.
[0049] A "Mooney unit" is an arbitrary unit used to measure the
plasticity of raw, or unvulcanized rubber. The plasticity in Mooney
units is equal to the torque, measured on an arbitrary scale, on a
disk in a vessel that contains rubber at a temperature of
212.degree. F. (100.degree. C.) and that rotates at two revolutions
per minute.
[0050] The measurement of Mooney viscosity, i.e. Mooney viscosity
[ML.sub.1+4(100.degree. C.], is defined according to the standard
ASTM D-1646, herein incorporated by reference. In ASTM D-1646, it
is stated that the Mooney viscosity is not a true viscosity, but a
measure of shearing torque over a range of shearing stresses.
Measurement of Mooney viscosity is also described in the Vanderbilt
Rubber Handbook, 13th Ed., (1990), pages 565-566, also herein
incorporated by reference. Generally, polybutadiene rubbers have
Mooney viscosities, measured at 212.degree. F., of from about 25 to
about 65. Instruments for measuring Mooney viscosities are
commercially available such as a Monsanto Mooney Viscometer, Model
MV 2000. Another commercially available device is a Mooney
viscometer made by Shimadzu Seisakusho Ltd.
[0051] As will be understood by those skilled in the art, polymers
may be characterized according to various definitions of molecular
weight. The "number average molecular weight," M.sub.n, is defined
as: M n = N i / M i N i ##EQU1## where the limits on the summation
are from i=1 to i=infinity where N.sub.i is the number of molecules
having molecular weight M.sub.i.
[0052] "Weight average molecular weight," M.sub.w is defined as: M
w = N i .times. M i 2 N i .times. M i ##EQU2## where N.sub.i and
M.sub.i have the same meanings as noted above.
[0053] The "Z-average molecular weight," M.sub.z, is defined as: M
z = N i .times. M i a + 1 N i .times. M i a ##EQU3## where N.sub.i
and M.sub.i have the same meanings as noted above and a=2. M.sub.z
is a higher order molecular weight that gives an indication of the
processing characteristics of a molten polymer.
[0054] "M.sub.peak" is the molecular weight of the most common
fraction or sample, i.e. having the greatest population.
[0055] Considering these various measures of molecular weight,
provides an indication of the distribution or rather the "spread"
of molecular weights of the polymer under review.
[0056] A common indicator of the degree of molecular weight
distribution of a polymer is its "polydispersity", P: P = M w M n
##EQU4##
[0057] Polydispersity, also referred to as "dispersity", also
provides an indication of the extent to which the polymer chains
share the same degree of polymerization. If the polydispersity is
1.0, then all polymer chains must have the same degree of
polymerization. Since weight average molecular weight is always
equal to or greater than the number average molecular weight,
polydispersity, by definition, is equal to or greater than 1.0.
[0058] As used herein, the term "phr" refers to the number of parts
by weight of a particular component in an elastomeric or rubber
mixture, relative to 100 parts by weight of the total elastomeric
or rubber mixture.
The Molded Elastomeric Component
[0059] The present development is directed to an elastomeric rubber
composition for producing a molded sphere, such as a one-piece golf
ball, a molded core for a multi-piece golf ball, or a molded core
or center for a three-piece or thread wound golf ball. One or more
additional core layers may also be disposed about the core
component followed by one or more cover layers. Additionally, one
or more intermediate layers may also be present.
[0060] In accordance with this development, the molded component,
such as a molded core, comprises a polybutadiene composition
containing at least one curing agent and one or more metal
thiosulfates, such as sodium hexamethylene thiosulfates (DHTS). It
has been found that the addition of the hexamethylene
thiosulfate(s) enhances the combination of certain properties of
the resulting molded product.
[0061] A further advantage provided by the cured cores is that such
cores are relatively soft, i.e. having a relatively low
compression, yet exhibit high resilience, i.e. display drop
rebounds higher than those corresponding to rebounds associated
with conventional cores.
[0062] It is preferred that the base elastomer included in the
composition is a polybutadiene material. Polybutadiene has been
found to be particularly useful because it imparts to the golf
balls a relatively high coefficient of restitution. Polybutadiene
can be cured using a free radical initiator such as a peroxide. A
broad range for the weight average molecular weight of preferred
base elastomers is from about 50,000 to about 1,000,000. A more
preferred range for the molecular weight of the base elastomer is
from about 50,000 to about 500,000. As a base elastomer for the
core composition, high cis-1-4-polybutadiene is preferably
employed, or a blend of high cis-1-4-polybutadiene with other
elastomers may also be utilized. Most preferably, high
cis-1-4-polybutadiene having a weight-average molecular weight of
from about 100,000 to about 500,000 is employed.
[0063] One preferred polybutadiene for use in the core assemblies
of the present invention feature a cis-1,4 content of at least 90%
and preferably greater than 96% such as Cariflex.RTM. BR-1220
currently available from Dow Chemical, France; and Taktene.RTM. 220
currently available from Bayer, Orange, Tex.
[0064] For example, Cariflex.RTM. BR-1220 polybutadiene and
Taktene.RTM. 220 polybutadiene may be utilized alone, in
combination with one another, or in combination with other
polybutadienes. Generally, these other polybutadienes have Mooney
viscosities in the range of about 25 to 65 or higher. The general
properties of BR-1220 and Taktene.RTM. 220 are set forth below.
[0065] A. Properties of Cariflex.RTM. BR-1220 Polybutadiene
TABLE-US-00001 Physical Properties: Polybutadiene Rubber CIS 1,4
Content - 97%-99% Min. Stabilizer Type - Non Staining Total Ash -
0.5% Max. Specific Gravity - 0.90-0.92 Color - Transparent, clear,
Lt. Amber Moisture - 0.3% max. ASTM .RTM. 1416.76 Hot Mill Method
Polymer Mooney Viscosity - (35-45 Cariflex .RTM.) (ML1 + 4 @
212.degree. F.) 90% Cure - 10.0-13.0 Polydispersity 2.5-3.5
Molecular Weight Data: Trial 1 Trial 2 M.sub.n 80,000 73,000
M.sub.w 220,000 220,000 M.sub.z 550,000 M.sub.peak 110,000
[0066] B. Properties of Taktene.RTM. 220 Polybutadiene
TABLE-US-00002 Physical Properties: Polybutadiene Rubber CIS 1,4
Content (%) - 98% Typical Stabilizer Type - Non Staining 1.0-1.3%
Total Ash - 0.25 Max. Raw Polymer Mooney Visc. - 35-45 40 Typical
(ML1 + 4'@212 Deg. F./212.degree. F.) Specific Gravity - 0.91 Color
- Transparent - almost colorless (15 APHA Max.) Moisture % - 0.30%
Max. ASTM .RTM. 1416-76 Hot Mill Method Product A relatively low to
mid Mooney viscosity, non-staining, solution Description
polymerized, high cis-1,4-polybutadiene rubber. Property Range Test
Method Raw Polymer Properties Mooney viscosity 40 .+-. 5 ASTM .RTM.
D 1646 1 + 4(212.degree. F.) Volatile matter (wt %) 0.3 max. ASTM
.RTM. D 1416 Total Ash (wt %) 0.25 max. ASTM .RTM. D 1416
Cure.sup.(1)(2) Characteristics Minimum torque M.sub.L (dN m) 9.7
.+-. 2.2 ASTM .RTM. D 2084 (lbf) in) 8.6 .+-. 1.9 ASTM .RTM. D 2084
Maximum torque M.sub.H (dN m) 35.7 .+-. 4.8 ASTM .RTM. D 2084 (lbf
in) 31.6 .+-. 4.2 ASTM .RTM. D 2084 t.sub.21 (min) 4 .+-. 1.1 ASTM
.RTM. D 2084 t'50 (min) 9.6 .+-. 2.5 ASTM .RTM. D 2084 t'90 (min)
12.9 .+-. 3.1 ASTM .RTM. D 2084 Other Product Features Property
Typical Value Specific gravity 0.91 Stabilizer type Non-staining
TAKTENE .RTM. 220 100 (parts by mass) Zinc oxide 3 Stearic acid 2
IRB #6 black (N330) 60 Naphthenic oil 15 TBBS 0.9 Sulfur 1.5
.sup.(1)Monsanto Rheometer at 160.degree. C., 1.7 Hz (100 cpm), 1
degree arc, micro-die .sup.(2)Cure characteristics determined on
ASTM .RTM. D 3189 MIM mixed compound: *This specification refers to
product manufactured by Bayer Corp., Orange, Texas, U.S.A.
[0067] An example of a high Mooney viscosity polybutadiene suitable
for use with the present invention includes Cariflex.RTM. BCP 820,
from Shell Chimie of France. Although this polybutadiene produces
cores exhibiting higher C.O.R. values, it is somewhat difficult to
process using conventional equipment. The properties and
characteristics of this preferred polybutadiene are set forth
below. TABLE-US-00003 Properties of Shell Chimie BCP 820 (Also
Known As BR-1202J) Property Value Mooney Viscosity (approximate)
70-83 Volatiles Content 0.5% maximum Ash Content 0.1% maximum Cis
1,4-polybutadiene Content 95.0% minimum Stabilizer Content 0.2 to
0.3% Polydispersity 2.4-3.1 Molecular Weight Data: Trial 1 Trial 2
M.sub.n 110,000 111,000 M.sub.w 300,000 304,000 M.sub.z 680,000
M.sub.peak 175,000
[0068] Examples of further polybutadienes include those obtained by
using a neodymium-based catalyst, such as Neo Cis 40 and Neo Cis 60
from Enichem, Polimeri Europa America, 200 West Loop South, Suite
2010, Houston, Tex. 77027, and those obtained by using a neodymium
based catalyst, such as CB-22, CB-23, and CB-24 from Bayer Co.,
Pittsburgh, Pa. The properties of these polybutadienes are given
below. TABLE-US-00004 A. Properties of Neo Cis 40 and 60 Properties
of Raw Polymer Microstructure 1,4 cis (typical) 97.5% 1,4 trans
(typical) 1.7% Vinyl (typical) 0.8% Volatile Matter (max) 0.75% Ash
(max) 0.30% Stabilizer (typical) 0.50% Mooney Viscosity, ML 1 + 4
at 100.degree. C. 38-48 and 60-66 Properties of compound (typical)
Vulcanization at 145.degree. C. Tensile strength, 35' cure, 16 MPa
Elongation, 35' cure, 440% 300% modulus, 35' cure, 9.5 MPa
[0069] TABLE-US-00005 B. Properties of CB-22 TESTS RESULTS
SPECIFICATIONS 1. Mooney-Viscosity ML1 + 4 100 Cel/ASTM .RTM.-sheet
ML1 + 1 Minimum 58 MIN. 58 ME Maximum 63 MAX. 68 ME Median 60 58-68
ME 2. Content of ash DIN 53568 Ash 0.1 MAX. 0.5% 3. Volatile matter
heating 3 h/105 Cel Loss in weight 0.11 MAX. 0.5% 4. Organic acid
Bayer Nr. 18 Acid 0.33 MAX. 1.0% 5. CIS-1,4 content IR-spectroscopy
CIS 1,4 97.62 MIN. 96.0% 6. Vulcanization behavior Monsanto MDR/160
Cel DIN 53529 Compound after ts01 3.2 2.5-4.1 min t50 8.3 6.4-9.6
min t90 13.2 9.2-14.0 min s'min 4.2 3.4-4.4 dN m s'max 21.5
17.5-21.5 dN m 7. Informative data Vulcanization 150 Cel 30 min
Tensile ca. 15.0 Elongation at break ca. 450 Stress at 300%
elongation ca. 9.5
[0070] TABLE-US-00006 C. Properties of CB-23 TESTS RESULTS
SPECIFICATIONS 1. Mooney-Viscosity ML1 + 4 100 Cel/ASTM .RTM.-sheet
ML1 + 4 Minimum 50 MIN. 46 ME Maximum 54 MAX. 56 ME Median 51 46-56
ME 2. Content of ash DIN 53568 0.09 MAX. 0.5% Ash 3. Volatile
matter DIN 53526 Loss in weight 0.19 MAX. 0.5% 4. Organic acid
Bayer Nr. 18 Acid 0.33 MAX. 1.0% 5. CIS-1,4 content IR-spectroscopy
CIS 1,4 97.09 MIN. 96.0% 6. Vulcanization behavior Monsanto MDR/160
Cel DIN 53529 Compound after MIN. 96.0 ts01 3.4 2.4-4.0 min t50 8.7
5.8-9.0 min t90 13.5 8.7-13.5 min s'min 3.1 2.7-3.8 dN m s'max 20.9
17.7-21.7 dN m 7. Vulcanization test with ring Informative data
Tensile ca. 15.5 Elongation at break ca. 470 Stress at 300%
elongation ca. 9.3
[0071] TABLE-US-00007 D. Properties of CB-24 TESTS RESULTS
SPECIFICATIONS 1. Mooney-Viscosity ML1 + 4 100 Cel/ASTM .RTM.-sheet
ML1 + 4 Minimum 44 MIN. 39 ME Maximum 46 MAX. 49 ME Median 45 39-49
ME 2. Content of ash DIN 53568 Ash 0.12 MAX. 0.5% 3. Volatile
matter DIN 53526 Loss in weight 0.1 MAX. 0.5% 4. Organic acid Bayer
Nr. 18 Acid 0.29 MAX. 1.0% 5. CIS-1,4 content IR-spectroscopy CIS
1,4 96.73 MIN. 96.0% 6. Vulcanization behavior Monsanto MDR/160 Cel
DIN 53529 Compound after masticator ts01 3.4 2.6-4.2 min t50 8.0
6.2-9.4 min t90 12.5 9.6-14.4 min s'min 2.8 2.0-3.0 dN m s'max 19.2
16.3-20.3 dN m 7. Informative data Vulcanization 150 Cel 30 min
Tensile ca 15.0 Elongation at break ca. 470 Stress at 300%
elongation ca. 9.1
[0072] Alternative polybutadienes include fairly high Mooney
viscosity polybutadienes including the commercially available BUNAS
CB series polybutadiene rubbers manufactured by the Bayer Co.,
Pittsburgh, Pa. The BUNA.RTM. CB series polybutadiene rubbers are
generally of a relatively high purity and light color. The low gel
content of the BUNA.RTM. CB series polybutadiene rubbers ensures
almost complete solubility in styrene. The BUNA.RTM. CB series
polybutadiene rubbers have a relatively high cis-1,4 content.
Preferably, each BUNA.RTM. CB series polybutadiene rubber has a
cis-1,4 content of at least 96%. Additionally, each BUNA.RTM. CB
series polybutadiene rubber exhibits a different solution
viscosity, preferably from about 42 mPas to about 170 mPas, while
maintaining a relatively constant solid Mooney viscosity value
range, preferably of from about 38 to about 52. The BUNA.RTM. CB
series polybutadiene rubbers preferably have a vinyl content of
less than about 12%, more preferably a vinyl content of about 2%.
In this regard, below is a listing of commercially available
BUNA.RTM. CB series polybutadiene rubbers and the solution
viscosity and Mooney viscosity of each BUNA.RTM. CB series
polybutadiene rubber.
Solution Viscosity and Mooney Viscosity of BUNA.RTM. CB Series
Polybutadiene Rubbers
[0073] TABLE-US-00008 BUNA .RTM. CB BUNA .RTM. CB BUNA .RTM. CB
BUNA .RTM. CB BUNA .RTM. CB Property 1405 1406 1407 1409 1410
Solution 50 +/- 7 60 +/- 7 70 +/- 10 90 +/- 10 100 +/- 10 Viscosity
mPa s Mooney 45 +/- 5 45 +/- 5 45 +/- 5 45 +/- 5 45 +/- 5 Viscosity
mL 1 + 4 100.degree. C. BUNA .RTM. CB BUNA .RTM. CB BUNA .RTM. CB
BUNA .RTM. CB BUNA .RTM. CB Property 1412 1414 1415 1416 10
Solution 120 +/- 10 140 +/- 10 150 +/- 10 160 +/- 10 140 +/- 20
Viscosity mPa s Mooney 45 +/- 5 45 +/- 5 45 +/- 5 45 +/- 5 47 +/- 5
Viscosity mL 1 + 4 100.degree. C.
Properties
[0074] TABLE-US-00009 BUNA .RTM. BUNA .RTM. BUNA .RTM. BUNA .RTM.
Property Test Method Units CB 1406 CB 1407 CB 1409 CB 1410 Catalyst
Cobalt Cobalt Cobalt Cobalt Cis-1,4 IR % .gtoreq.96 .gtoreq.96
.gtoreq.96 .gtoreq.96 Content Spectroscopy; AN-SAA 0422 Volatile
ISO 248/ % .ltoreq.0.5 .ltoreq.0.5 .ltoreq.0.5 .ltoreq.0.5 Matter
ASTM D 1416 Ash Content ISO 247/ % .ltoreq.0.1 .ltoreq.0.1
.ltoreq.0.1 .ltoreq.0.1 ASTM D 1416 Mooney ISO 289/DIN MU 45 .+-. 5
45 .+-. 5 45 .+-. 5 45 .+-. 5 Viscosity ML 53 523/ASTM (1 + 4)
100.degree. C. D 1646 Solution ASTM D 445/ mPa s 60 .+-. 7 70 .+-.
7 90 .+-. 10 100 .+-. 10 Viscosity, 5% DIN 51 562 in styrene
Styrene 08-02.08.CB ppm .ltoreq.100 .ltoreq.100 .ltoreq.100
.ltoreq.100 insoluble: dry gel Color in ISO 6271/ APHA .ltoreq.10
.ltoreq.10 .ltoreq.10 .ltoreq.10 styrene ASTM D 1209 Solubility in
in in in aliphatic aliphatic aliphatic aliphatic hydrocarbons
hydrocarbons hydrocarbons hydrocarbons Total Amount AN-SAA 0583 %
0.2 0.2 0.2 0.2 of Stabilizer BUNA .RTM. BUNA .RTM. BUNA .RTM. BUNA
.RTM. Property Test Method Units CB 1412 CB 1414 CB 1415 CB 1416
Catalyst Cobalt Cobalt Cobalt Cobalt Cis-1,4 IR % .gtoreq.96
.gtoreq.96 .gtoreq.96 .gtoreq.96 Content Spectroscopy; AN-SAA 0422
Volatile ISO 248/ % .ltoreq.0.5 .ltoreq.0.5 .ltoreq.0.5 .ltoreq.0.5
Matter ASTM D 1416 Ash Content ISO 247/ % .ltoreq.0.1 .ltoreq.0.1
.ltoreq.0.1 .ltoreq.0.1 ASTM D 1416 Mooney ISO 289/DIN MU 45 .+-. 5
45 .+-. 5 45 .+-. 5 45 .+-. 5 Viscosity ML 53 523/ASTM (1 + 4)
100.degree. C. D 1646 Solution ASTM D 445/ mPa s 120 .+-. 10 140
.+-. 10 150 .+-. 10 160 .+-. 10 Viscosity, 5% DIN 51 562 in styrene
Styrene 08-02.08.CB ppm .ltoreq.100 .ltoreq.100 .ltoreq.100
.ltoreq.100 insoluble: dry gel Color in ISO 6271/ APHA .ltoreq.10
.ltoreq.10 .ltoreq.10 .ltoreq.10 styrene ASTM D 1209 Solubility in
in in in aliphatic aliphatic aliphatic aliphatic hydrocarbons
hydrocarbons hydrocarbons hydrocarbons Total Amount AN-SAA 0583 %
0.2 0.2 0.2 0.2 of Stabilizer
[0075] In addition to the polybutadiene rubbers noted above,
BUNA.RTM. CB 10 polybutadiene rubber is also very desirous to be
included in the composition of the present invention. BUNA CB 10
polybutadiene rubber has a relatively high cis-1,4 content, good
resistance to reversion, abrasion and flex cracking, good low
temperature flexibility and high resilience. The BUNA.RTM. CB 10
polybutadiene rubber preferably has a vinyl content of less than
about 12%, more preferably about 2% or less. Listed below is a
brief description of the properties of the BUNA.RTM. CB 10
polybutadiene rubber.
Properties of BUNA.RTM. CB 10 Polybutadiene Rubber
[0076] TABLE-US-00010 Value Unit Test method Raw Material
Properties Volatile Matter .ltoreq.0.5 wt-% ISO 248/ASTM D 5668
Mooney viscosity 47 .+-. 5 MU ISO 289/ASTM D 1646 ML(1 + 4) @
100.degree. C. Solution viscosity, 140 .+-. 20 mPa s ASTM D 445/ISO
5.43 wt % in toluene 3105 (5% in toluene) Cis-1,4 content
.gtoreq.96 wt-% IR Spectroscopy, AN-SAA 0422 Color, Yellowness
.ltoreq.10 ASTM E 313-98 Index Cobalt content .ltoreq.5 ppm DIN 38
406 E22 Total Stabilizer .gtoreq.0.15 wt-% AN-SAA 0583 content
Specific Gravity 0.91 Monsanto Rheometer MDR 2000E, 160.degree.
C./30 min./.alpha. = .+-.0.5.degree. C. Vulcanization Properties
(Test formulation from ISO 2476/ASTM D 3189 (based on IRB 7))
Torque Minimum 3.5 .+-. 0.7 dNm ISO 6502/ASTM D5289 (ML) Torque
Maximum 19.9 .+-. 2.4 dNm ISO 6502/ASTM D5289 (MH) Scorch Time,
t.s..sub.1 2.9 .+-. 0.6 min ISO 6502/ASTM D5289 Cure Time,
t.c..sub.50 8.7 .+-. 1.7 min ISO 6502/ASTM D5289 Cure Time,
t.c..sub.90 12.8 .+-. 2.4 min ISO 6502/ASTM D5289
[0077] Furthermore, as noted, relatively low or mid-range Mooney
viscosity polybutadienes (i.e., Cariflex BR-1220) can be utilized
with the hexamethylene thiosulfate and an optional halogenated
thiophenol to produce properties similar to those produced by
higher solution viscosity/higher linearity polybutadienes (i.e., CB
10, etc.). This is discussed in more detail below.
[0078] The base elastomer utilized in the present invention can
also be mixed with other elastomers. These include natural rubbers,
polyisoprene rubber, SBR rubber (styrene-butadiene rubber) and
others to produce certain desired core properties.
[0079] Also included with the base elastomer is a metal
thiosulfate. The metal thiosulfate can be defined by the general
formula below:
mM.sup.n[O.sub.3S--S--(CH.sub.2).sub.x(CHA).sub.y(CHB).sub.z--S--SO.sub.3-
].sup.-(mn).smallcircle.kH.sub.2O where k=0-12, x=2-10, y=0-10,
z=0-10, M=a metal cation, and A or B is selected from group (1) or
group (2) where: [0080] (1) includes --H,
--(CH.sub.2).sub.q--S--SO.sub.3.sup.-,
--(CH.sub.2).sub.q(CH.dbd.CR).sub.lCH.sub.2S--SO.sub.3.sup.-,
--(CH.sub.2).sub.q(CH.dbd.CR).sub.lCH.sub.3;
--(CH.sub.2).sub.q--CHR--CHRCO.sub.2H and l=1-4, R.dbd.H, CH.sub.3,
and q=0-8; or, [0081] (2) a substituent incorporating the
antioxidant, accelerator or initiator functionality.
[0082] For example, when M=sodium, k=2, m=2, n=1, x+y+z=6, A=H and
B=H, the metal thiosulfate is a hexamethylene thiosulfate such as
hexamethylene-1,6-bis(thiosulfate), disodium salt.
[0083] In this regard, the hexamethylene thiosulfate included in
the elastomeric composition of the present invention is preferably
hexamethylene-1,6-bis(thiosulfate), disodium salt, dihydrate (CAS
No. 5719-73-3), such as that which is available from Flexsys
America, Akron, Ohio, under the product name "Duralink.TM. DHTS".
This material is also known as disodium
hexamethylene-1,6-bisthiosulfate dihydrate, "HTS Na" or "DHTS".
These names have been utilized interchangeably or synonymously by
the manufacturer. The molecular weight of Duralink.TM. DHTS is
390.4, and it has a molecular formula of
C.sub.6--H.sub.16--O.sub.8--Na.sub.2--S.sub.4 as shown below in
Formula I: ##STR1##
[0084] According to the literature, this sodium hexamethylene
thiosulfate material has been utilized in rubber compositions in
the tire industry to provide improved thermal resistance and
dynamic properties. Additionally this material has been utilized in
sulfur based vulcanization systems to generate hybrid crosslinks
which provide increased retention of physical and dynamic
properties when exposed to anaerobic conditions at elevated
temperatures such as those experienced during over cure, when using
high curing temperatures, or produced during service life of the
tire. It is sometimes utilized in the tire industry to act as an
anti-reversion agent in sulfur vulcanization processes. Reversion
of rubber properties occurs due to relatively high tire cure
temperatures as well as high operational temperatures such as heavy
vehicular loads at high speeds.
[0085] The typical properties of Duralink.TM. DHTS are set forth
below: TABLE-US-00011 Duralink .TM. DHTS pdr-d-s dust suppressed
Product form fine powder Test method PRODUCT SPECIFICATIONS
Appearance white powder FF97.5 Assay (titration) (%) min. 95.0
FAg97.2 Chloride as NaCl (%) max. 1.0 FAc97.2 Moisture (%) 8.5-10.0
FAmp90.1 Additive (%) 1.0-2.0 FGr83.6 TYPICAL PROPERTIES Density at
25.degree. C. (kg/m.sup.3) 1390 Residue (%) max. <0.05% on150
.mu.m sieve
[0086] Preferably, the curing agent of the elastomeric composition
of the present invention is the reaction product of the selected
unsaturated carboxylic acid or acids and an oxide or carbonate of a
metal such as zinc, magnesium, barium, calcium, lithium, sodium,
potassium, cadmium, lead, tin, and the like. Preferably, the oxides
of polyvalent metals such as zinc, magnesium and calcium are used,
and most preferably, the oxide is zinc oxide.
[0087] Exemplary of the unsaturated carboxylic acids which find
utility in the present core compositions are acrylic acid,
methacrylic acid, itaconic acid, crotonic acid, sorbic acid, and
the like, and mixtures thereof. Preferably, the acid component is
either acrylic or methacrylic acid. Usually, from about 15 to about
50, and preferably from about 17 to about 35 parts by weight of the
carboxylic acid salt, such as zinc diacrylate (ZDA), is included
per 100 parts of the elastomer components in the core composition.
The unsaturated carboxylic acids and metal salts thereof are
generally soluble in the elastomeric base, or are readily
dispersible. Examples of such commercially available curing agents
include the zinc acrylates and zinc diacrylates available from
Sartomer Company, Inc., 502 Thomas Jones Way, Exton, Pa.
[0088] The free radical initiator included in the elastomeric
composition of the present development is any known polymerization
initiator which decomposes during the cure cycle. The term "free
radical initiator" as used herein refers to a chemical which, when
added to a mixture of the elastomeric blend and a metal salt of an
unsaturated, carboxylic acid, promotes crosslinking of the
elastomers by the metal salt of the unsaturated carboxylic acid.
The amount of the selected initiator present is dictated only by
the requirements of catalytic activity as a polymerization
initiator. Suitable initiators include peroxides, persulfates, azo
compounds and hydrazides. Peroxides which are readily commercially
available are conveniently used in the present invention, generally
in amounts of from about 0.1 to about 10.0 and preferably in
amounts of from about 0.3 to about 3.0 parts by weight per each 100
parts of elastomer, wherein the peroxide has a 40% level of active
peroxide. Blends or combinations of two or more peroxides may be
used to facilitate crosslinking. When using blends of peroxides, it
is preferred that the initiators of different reactivities or half
lifes are utilized.
[0089] Exemplary of suitable peroxides for the purposes of the
present invention are dicumyl peroxide, n-butyl 4,4'-bis
(butylperoxy) valerate, 1,1-bis(t-butylperoxy)-3,3,5-trimethyl
cyclohexane, di-t-butyl peroxide and 2,5-di-(t-butylperoxy)-2,5
dimethyl hexane and the like, as well as mixtures thereof. It will
be understood that the total amount of initiators used will vary
depending on the specific end product desired and the particular
initiators employed.
[0090] Examples of such commercial available peroxides are
Luperco.TM. 230 or 231 XL, a peroxyketal manufactured and sold by
Atochem, Lucidol Division, Buffalo, N.Y., and Trigonox.TM. 17/40 or
29/40, a peroxyketal manufactured and sold by Akzo Chemie America,
Chicago, Ill. The one hour half life of Luperco.TM. 231 XL and
Trigonox.TM. 29/40 is about 112.degree. C., and the one hour half
life of Luperco.TM. 230 XL and Trigonox.TM. 17/40 is about
129.degree. C. Luperco.TM. 230 XL and Trigonox.TM. 17/40 are
n-butyl-4,4-bis(t-butylperoxy) valerate and Luperco.TM. 231 XL and
Trigonox.TM. 29/40 are 1,1-di(t-butylperoxy) 3,3,5-trimethyl
cyclohexane.
[0091] More preferably, Trigonox.TM. 42-40B from Akzo Nobel of
Chicago, Ill. is used in the present development. Most preferably,
a solid form of this peroxide is used. Trigonox.TM. 4240B is
tert-Butyl peroxy-3,5,5-trimethylhexanoate. The liquid form of this
agent is available from Akzo under the designation Trigonox.TM.
42S.
[0092] Preferred co-agents which can be used with the above
peroxide polymerization agents include zinc diacrylate (ZDA), zinc
dimethacrylate (ZDMA), trimethylol propane triacrylate, and
trimethylol propane trimethacrylate, most preferably zinc
diacrylate. Other co-agents may also be employed and are known in
the art.
[0093] The elastomeric polybutadiene compositions of the present
invention can also optionally include one or more halogenated
organic sulfur compounds. Preferably, the halogenated organic
sulfur compound is a halogenated thiophenol of the formula below:
##STR2## wherein R.sub.1-R.sub.5 can be halogen groups, hydrogen,
alkyl groups, thiol groups or carboxylated groups. At least one
halogen group is included, preferably 3-5 of the same halogenated
groups are included, and most preferably 5 of the same halogenated
groups are part of the component. Examples of such fluoro-,
chloro-, bromo-, and iodo-thiophenols include, but are not limited
to 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-bromothiophehol;
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; 2,4-iodothiophenol;
3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol;
3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;
2,3,5,6-tetraiodothiophenol; and their metal salts thereof, and
mixtures thereof. The metal salt may be salts of zinc, calcium,
potassium, magnesium, sodium, and lithium.
[0094] Pentachlorothiophenol or a metallic salt of
pentachlorothiophenol is preferably included in the present
invention. For example, RD 1302 of Rheim Chemie of Trenton, N.J.
can be included therein. RD 1302 is a 75% masterbatch of Zn PCTP in
a high-cis polybutadiene rubber.
[0095] Other suitable pentachlorothiphenols include those available
from Dannier Chemical, Inc., Tustin, Calif., under the designation
Dansof P.TM.. The product specifications of Dansof P.TM. are set
forth below: TABLE-US-00012 Compound Name Pentachlorothiophenol
Synonym (PCTP) CAS # n/a Molecular Formula: C6Cl5SH Molecular
Weight: 282.4 Grade: Dansof P Purity: 97.0% (by HLPC) Physical
State: Free Flowing Powder Appearance Light Yellow to Gray Moisture
Content (K.F.) <0.4% Loss on Drying (% by Wt.): <0.4%
Particle Size: 80 mesh
[0096] The molecular structure of pentachlorothiophenol is
represented below: ##STR3##
[0097] A representative metallic salt of pentachlorothiophenol is
the zinc salt of pentachlorothiophenol (ZnPCTP) sold by Dannier
Chemical, Inc. under the designation Dansof Z.TM.. The properties
of this material are as follows: TABLE-US-00013 Compound Name Zinc
Salt of Pentachlorothiophenol Synonym Zn(PCTP) CAS # n/a Molecular
Formula: Molecular Weight: Grade: DR 14 Purity: =99.0% Physical
State: Free Flowing Powder Appearance Off-white/Gray Odor: Odorless
Moisture Content (K.F.) <0.5% Loss on Drying (% by Wt.):
<0.5% Mesh Size: 100 Specific Gravity 2.33
[0098] Pentachlorothiophenol or a metallic salt thereof is added to
the core material in an amount of 0.01 to 5.0 parts by weight,
preferably 0.1 to 2.0 parts by weight, more preferably 0.5 to 1.0
parts by weight, on the basis of 100 parts by weight of the base
elastomer.
[0099] In addition to the foregoing, filler materials can be
employed in the compositions of the invention to control the weight
and density of the ball. Fillers which are incorporated into the
compositions should be in finely divided form, typically in a size
generally less than about 20 mesh, preferably less than about 100
mesh U.S. standard size. Preferably, the filler is one with a
specific gravity of from about 0.5 to about 19.0. Examples of
fillers which may be employed include, for example, silica, clay,
talc, mica, asbestos, glass, glass fibers, barytes (barium
sulfate), limestone, lithophone (zinc sulphide-barium sulfate),
zinc oxide, titanium dioxide, zinc sulphide, calcium metasilicate,
silicon carbide, diatomaceous earth, particulate carbonaceous
materials, micro balloons, aramid fibers, particulate synthetic
plastics such as high molecular weight polyethylene, polystyrene,
polyethylene, polypropylene, ionomer resins and the like, as well
as cotton flock, cellulose flock and leather fiber. Powdered metals
such as titanium, tungsten, aluminum, bismuth, nickel, molybdenum,
copper, brass and their alloys also may be used as fillers.
[0100] The amount of filler employed is primarily a function of
weight restrictions on the weight of a golf ball made from those
compositions. In this regard, the amount and type of filler will be
determined by the characteristics of the golf ball desired and the
amount and weight of the other ingredients in the core composition.
The overall objective is to closely approach the maximum golf ball
weight of 1.620 ounces (45.92 grams) set forth by the U.S.G.A.
[0101] The compositions of the invention also may include various
processing aids known in the rubber and molding arts, such as fatty
acids. Generally, free fatty acids having from about 10 carbon
atoms to about 40 carbon atoms, preferably having from about 15
carbon atoms to about 20 carbon atoms, saturated or unsaturated,
may be used. Examples of fatty acids which may be used include
stearic acid, linoleic acid and oleic acids, as well as mixtures
thereof. When included in the compositions of the invention, the
fatty acid component is present in amounts of from about 1 part by
weight per 100 parts elastomer, preferably in amounts of from about
2 parts by weight per 100 parts elastomer to about 5 parts by
weight per 100 parts elastomer. Examples of processing aids which
may be employed include, for example, calcium stearate, barium
stearate, zinc stearate, lead stearate, basic lead stearate, zinc
oleate, magnesium oleate, calcium oleate, dibasic lead phosphite,
dibutyltin dilaurate, dibutyltin dimealeate, dibutyltin mercaptide,
as well as dioctyltin and stannane diol derivatives.
[0102] Coloring pigments also may be included in the compositions
of the invention. Useful coloring pigments include, for example,
titanium dioxide, the presence of which simplifies the surface
painting operation of a one piece golf ball. In some cases,
coloring pigments eliminate the need for painting such as, for
example, a one piece golf ball intended for use on driving
ranges.
[0103] The core compositions of the present invention may
additionally contain any other suitable and compatible modifying
ingredients including, but not limited to, metal oxides, fatty
acids, and diisocyanates and polypropylene powder resin.
[0104] Various activators may also be included in the compositions
of the present invention. For example, zinc oxide and/or magnesium
oxide are activators for the polybutadiene. The activator can range
from about 2 to about 50 parts by weight per 100 parts by weight of
the rubbers (phr) component, preferably at least 3 to 5 parts by
weight per 100 parts by weight of the rubbers.
[0105] Higher specific gravity fillers may be added to the core
composition so long as the specific core weight limitations are
met. The amount of additional filler included in the core
composition is primarily dictated by weight restrictions and
preferably is included in amounts of from about 0 to about 100
parts by weight per 100 parts rubber. Ground flash filler may be
incorporated and is preferably mesh ground up center stock from the
excess flash from compression molding. It lowers the cost and may
increase the hardness of the ball.
[0106] Diisocyanates may also be optionally included in the core
compositions. When utilized, the diisocyanates are included in
amounts of from about 0.2 to about 5.0 parts by weight based on 100
parts rubber. Exemplary of suitable diisocyanates is
4,4'-diphenylmethane diisocyanate and other polyfunctional
isocyanates known to the art.
[0107] Furthermore, the dialkyl tin difatty acids set forth in U.S.
Pat. No. 4,844,471, the dispersing agents disclosed in U.S. Pat.
No. 4,838,556, and the dithiocarbamates set forth in U.S. Pat. No.
4,852,884 may also be incorporated into the polybutadiene
compositions of the present invention. The specific types and
amounts of such additives are set forth in the above identified
patents, which are incorporated herein by reference.
[0108] A golf ball or a molded component thereof formed from
compositions of the invention may be made by conventional mixing
and compounding procedures used in the rubber industry. For
example, the ingredients may be intimately mixed using, for
example, two roll mills or a BANBURY.RTM. mixer, until the
composition is uniform, usually over a period of from about 5 to 20
minutes. The sequence of addition of components is not critical. A
preferred blending sequences is as follows.
[0109] The elastomer, sodium hexamethylene thiosulfate (DHTS), the
halogenated thiophenol (if desired), fillers, zinc salt, metal
oxide, fatty acid, and the metallic dithiocarbamate (if desired),
surfactant (if desired), and, tin difatty acid (if desired), are
blended for about 7 minutes in an internal mixer such as a
BANBURY.RTM. mixer. As a result of shear during mixing, the
temperature rises to about 200.degree. F. The initiator and
diisocyanate are then added and the mixing continued until the
temperature reaches about 220.degree. F. whereupon the batch is
discharged onto a two roll mill, mixed for about one minute and
sheeted out. The mixing is desirably conducted in such a manner
that the composition does not reach incipient polymerization
temperature during the blending of the various components.
[0110] The composition can be formed into a core structure by any
one of a variety of molding techniques, e.g. injection,
compression, or transfer molding. If the core is compression
molded, the sheet is then rolled into a "pig" and then placed in a
BARWELL.RTM. preformer and slugs are produced. The slugs are then
subjected to compression molding at about 320.degree. F. for about
14 minutes. After molding, the molded cores are cooled at room
temperature for about 4 hours or in cold water for about one
hour.
[0111] Usually the curable component of the composition will be
cured by heating the composition at elevated temperatures on the
order of from about 275.degree. F. to about 350.degree. F.,
preferably and usually from about 290.degree. F. to about
325.degree. F., with molding of the composition effected
simultaneously with the curing thereof. When the composition is
cured by heating, the time required for heating will normally be
short, generally from about 10 to about 20 minutes, depending upon
the particular curing agent used. Those of ordinary skill in the
art relating to free radical curing agents for polymers are
conversant with adjustments to cure times and temperatures required
to effect optimum results with any specific free radical agent.
[0112] After molding, the core is removed from the mold and the
surface may be treated to facilitate adhesion thereof to the
covering materials. Surface treatment can be effected by any of the
several techniques known in the art, such as corona discharge,
ozone treatment, sand blasting, and the like. Preferably, surface
treatment is effected by grinding with an abrasive wheel
(centerless grinding) whereby a thin layer of the molded core is
removed to produce a round core having a diameter of 1.28 to 1.63
inches, preferably about 1.37 to about 1.600 inches, and most
preferably, 1.585 inches. Alternatively, the cores are used in the
as-molded state with no surface treatment.
[0113] One or more cover layers can be applied about the present
core in accordance with procedures known in the art. The
composition of the cover may vary depending upon the desired
properties for the resulting golf ball. Any known cover composition
to form a cover can be used. U.S. Pat. Nos. 6,290,614; 6,277,921;
6,220,972; 6,150,470; 6,126,559; 6,117,025; 6,100,336; 5,779,562;
5,688,869; 5,591,803; 5,542,677; 5,368,304,5,312,857, and 5,306,760
herein entirely incorporated by reference, disclose cover
compositions, layers, and properties suitable for forming golf
balls in accordance with the present invention.
[0114] In a multi-layer golf ball, the core is converted into a
golf ball by providing at least one layer of covering material
thereon. The thickness of the cover layer(s) is dependent upon the
overall ball size desired. However, typical ranges in cover
thicknesses are from about 0.005 to about 0.250 inches, preferably
from about 0.010 to about 0.090 inches, and more preferably from
about 0.015 to about 0.040 inches.
[0115] In this regard, the present development can be used in
forming golf balls of a wide variety of sizes. The U.S.G.A.
dictates that the size of a competition golf ball must be at least
1.680 inches in diameter, however, golf balls of any size can be
used for leisure golf play.
[0116] Furthermore, the preferred diameter of the golf balls is
from about 1.680 inches to about 1.800 inches. The more preferred
diameter is from about 1.680 to about 1.780 inches. A diameter of
from about 1.680 to about 1.760 inches is most preferred. Oversize
golf balls with diameters above 1.700 inches are also within the
scope of this development.
[0117] The cover or the layers of the multi-layer cover may be
formed from generally the same resin composition, or may be formed
from the different resin compositions with similar hardnesses. For
example, one cover layer may be formed from an ionomeric resin of
ethylene and methacrylic acid, while another layer is formed from
an ionomer of ethylene and acrylic acid. One or more cover layers
may contain polyamides or polyamide-nylon copolymers or intimate
blends thereof. Furthermore, polyurethanes, Pebax.RTM.
polyetheramides, Hytrel.RTM. polyesters, natural or synthetic
balatas, and/or thermosetting polyurethanes/polyureas can be used.
Preferably, the cover composition is an ionomer blend, a
polyurethane/polyurea or blends thereof. In order to visibly
distinguish the layers, various colorants, metallic flakes,
phosphorous, florescent dyes, florescent pigments, etc., can be
incorporated in the resin.
[0118] The covered golf ball can be formed in any one of several
methods known in the art. For example, the molded core may be
placed in the center of a golf ball mold and the ionomeric
resin-containing cover composition injected into and retained in
the space for a period of time at a mold temperature of from about
40.degree. F. to about 120.degree. F.
[0119] Alternatively, the cover composition may be injection molded
at about 300.degree. F. to about 450.degree. F. into
smooth-surfaced hemispherical shells, a core and two such shells
placed in a dimpled golf ball mold and unified at temperatures on
the order of from about 200.degree. F. to about 300.degree. F.
[0120] The golf ball produced is then painted and marked, painting
being effected by spraying techniques.
[0121] The present invention is further illustrated by the
following examples in which the parts of the specific ingredients
are by weight. 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.
EXAMPLE 1
[0122] Several spherical core components were produced utilizing
the formulations set forth below (all amounts are parts by weight
unless otherwise indicated): TABLE-US-00014 Control Ingredients
(grams) A B C D Core Masterblend.sup.1 165.65 165.65 165.65 165.65
Dansof Z.sup.2 -- 0.5 -- -- RD 1302 Zn PCTP MB.sup.3 -- 0.66 --
Duralink DHTS.sup.4 -- -- -- 1 Size 1.579 1.58 1.578 1.576 Weight
38.74 38.8 38.7 38.8 I Comp 0.0913 0.1030 0.1045 0.0899 COR 0.8059
0.8052 0.8050 0.8074 Nes factor 897.2 908.2 909.5 897.3 Nes Diff 11
12.3 0.1 .sup.1Masterblend: CB 10 70 NeoCis 60 30 Zn Oxide 19.4 Zn
Stearate 16 ZDA 29 Trig 42/40 1.25 165.65 .sup.2Dansof Z is a zinc
salt of pentachlorothiophenol (Zn PCTP) available from Dannier
Chemical, Inc., Tustin, CA. .sup.3RD 1302 is Zn PCTP masterbatch
from Rhein Chemie, Trenton, NJ. It is a 75% masterbatch of Zn PCTP
in a high-cis polybutadiene rubber. .sup.4Duralink DHTS is
1,6-bis(thiosulfate), disodium salt, dihydrate available from
Flexsys America, Akron, Ohio.
[0123] The results indicated that the addition of the sodium
hexamethylene-1,6-biothiosulfate, dihydrate (i.e., Duralink DHTS)
to a high solution viscosity/high linearity polybutadiene material
(i.e., CB 10, etc.) produced a faster, more resilient core. See,
for example, Formulation 1D in comparison to Formulation 1A
(Control) wherein an increase of C.O.R. of 15 points was noted.
Furthermore, the addition of the sodium
hexamethylene-1,6-bisthiosulfate, and dihydrate also produced a
further increase in resilience than just the use of the zinc salt
of pentachlorothiophenol (Zn-PCTP) alone. See, for example, the
increase in C.O.R. produced by Formulation 1D in comparison to
Formulations 1B and 1C.
EXAMPLE 2
[0124] Additional core formulations were produced to determine
whether any synergies existed through the combined use of the
hexamethylene-1,6-bisthiosulfate, disodium, dihydrate along with a
pentachlorothiophenol. These formulations are set forth below:
TABLE-US-00015 Control Ingredients (grams) A B C D Core
Masterblend.sup.1 165.65 165.65 165.65 165.65 RD 1302 Zn PCTP MB --
0.66 0.66 0.66 Duralink DHTS -- -- 1 2 Size 1.501 1.503 1.503 1.502
Weight 34.17 34.21 34.32 34.35 I Comp 0.0833 0.0930 0.0943 0.0964
COR 0.8146 0.8146 0.8177 0.8121 Nes factor.sup.2 897.9 907.6 912
908.5 .sup.1Core Masterblend: CB 10 70 NeoCis 60 30 Zn Oxide 19.4
Zn Stearate 16 ZDA 29 Trig 42/40 1.25 165.65 .sup.2Nes factor is
determined by taking the sum of the Instrom compression and
resilience (C.O.R.) measurements and multiplying this value by
1000. It represents an optimal combination of softer but more
resilient cores.
[0125] The data indicated that the addition of the
hexamethylene-1,6-bisthiosulfate, disodium salt, dihydrate
(Duralink DHTS), along with the zinc salt of pentachlorothiophenol
(Zn-PCTP) to high solution viscosity/high linearity polybutadiene
compositions (i.e., CB 10, etc.) produced cores with enhanced
resilience (i.e., higher C.O.R.) and/or compression (softness).
See, for example, a comparison of Formulation 2C with Formulation
2A or 2B. These combinations also produced an enhanced combination
of compression and resilience characteristics as noted by the Nes
factor characteristics.
[0126] Such synergistic effects were also noted when lower solution
viscosity/lower linearity materials were utilized. This is shown
below: TABLE-US-00016 H I J K Cariflex 1220 65 65 65 65 Neo Cis 60
35 35 35 35 Zinc Oxide 19.8 19.8 19.8 19.8 Zinc Stearate 16 146 16
16 ZDA 30.5 30.5 30.5 30.5 Trigonox 42/40 1.25 1.25 1.25 1.25 RD
1302P Zn PCTP MB 0.66 0.66 0 0 Duralink DHTS 0 1 0 1 Size Pole
1.528 1.531 1.53 1.532 Size Eq 1.532 1.534 1.531 1.533 Weight 35.91
36.14 35.94 36.08 Instron Comp 0.1012 0.1006 0.0915 0.0901 C.O.R.
0.8086 0.8132 0.8039 0.8079 Nes factor 909.8 913.8 895.4 898
[0127] As shown, the combination of DHTS and the Zn-PCTP in
Formulation I produced a far greater combination of enhanced
compression and resilience (i.e., Nes factor of 913.8) than the
remaining formulations. Additionally, the data also demonstrates
that the addition of DHTS alone in Formulation K resulted in
enhanced resilience and/or compression than that of Control
Formulation J.
EXAMPLE 3
[0128] Several different types of polybutadienes (CB 10, Necodene
60, and Neo Cis 60) and zinc diacrylates (ZDA), as well as varying
amounts of zinc stearate, etc., were added to various formulations
and compared to the use of the hexamethylene thiosulfate (DHTS) in
combination with the zinc salt of pentachlorothiophenol (Zn-PCTP).
These formulations are presented below: TABLE-US-00017 A B C D
Parts BW Parts BW Parts BW Parts BW CB 10 70 420 70 420 0 0 0 0
Neodene 60 0 0 0 0 100.00 600 100 600 Neo Cis 60 30 180 30 180 0 0
0 0 Zinc Oxide 18.90 113.4 17.5 105 17.5 105 16.5 99 Zinc Stearate
16 96 16 96 16 96 3 18 TF ZDA 30 180 0 0 0 0 0 0 ZDA.sup.1 0 0 34
204 34 204 35 210 Zn PCTP MB 0.67 4.02 0.67 4.05 0.67 4.05 0.67
4.05 Duralink DHTS 0 0 0 0 1 6 1 6 Trig 42/40 1.25 7.5 1.25 7.5
1.25 7.5 1.25 7.5 Color Orange Purple Gold Tan Size Pole 1.505
1.507 1.504 1.503 Size EQ 1.505 1.507 1.505 1.503 Weight 34.16
34.05 34.03 34.07 Instron Comp 0.1017 0.1012 0.1004 0.0993 COR
0.8100 0.8107 0.8129 0.8170 Nes factor 912 912 913 916 .sup.1ZDA is
SR 416, a modified ZDA, available from Sartomer.
[0129] The results indicated that the addition of the hexamethylene
thiosulfate increased the C.O.R. of the core. See Formulations 3C
and 3D in comparison to the remaining formulations. This is further
shown in the additional formulations listed below. TABLE-US-00018 1
2 3 Parts BW Parts BW Parts BW CB 10 70 420 70 420 70 420 Neo Cis
60 30 180 30 180 30 180 Zinc Oxide 18.9 113.4 16.3 97.8 18.1 108.6
Zinc Stearate 16 96 3 18 16 96 TF ZDA 30 180 0 0 32 192 ZDA.sup.1 0
0 37 222 0 0 Zn PCTP MB 0.67 4.02 0.67 4.02 1 6 Duralink HTS 0 0 1
6 1.5 9 Trig 42/40 1.25 7.5 1.25 7.5 1.25 7.5 Color Size Pole 1.504
1.503 1.503 Size EQ 1.503 1.503 1.503 Weight 33.89 34.06 33.90
Instron Comp 0.1042 0.0974 0.1049 COR 0.8086 0.8178 0.8115 Nes
factor 913 915 916 .sup.1ZDA is SR 416, a modified ZDA available
from Sartomer
EXAMPLE 4
[0130] Hexamethylene thiosulfate (DHTS) was added to several
conventional core formulations containing the zinc salt of
pentachlorothiophenol (Zn-PCTP) and compared to core formulations
produced utilizing a high viscosity/high linearity polymer (i.e.,
CB 10) and pentachlorothiophenol. In this regard, the following
core formulations were produced.
[0131] A. Polybutadiene Formulations Containing Hexamethylene
Thiosulfate (DHTS) TABLE-US-00019 Material S.G. Parts Volume 100%
Caraflex BR-1220 0.91 65.00 71.43 39.90 Neo Cis 60 0.91 35.00 38.46
21.49 Zinc Oxide 5.57 20.00 3.59 12.28 Zinc Stearate 1.09 10.00
9.17 6.14 ZDA 2.1 30.15 14.36 18.51 Duralink DHTS 1.39 1.00 0.72
0.61 Zn PCTP 2.3 0.50 0.22 0.31 Trig 42/40B 1.4 1.25 0.89 0.77
Totals 1.173 162.90 138.84 100.00
[0132] B. High Viscosity/High Linearity Polybutadiene Formulations
without Hexamethylene Thiosulfate (DHTS) TABLE-US-00020 Material
S.G. Parts Volume 100% CB 10 0.91 70.00 76.92 41.67 Neo Cis 60 0.91
30.00 32.97 17.86 Zinc Oxide 5.57 20.75 3.73 12.35 Zinc Stearate
1.09 16.00 14.68 9.52 ZDA 2.1 29.50 14.05 17.56 Zn PCTP 2.3 0.50
0.22 0.30 Trig 42/40B 1.4 1.25 0.89 0.74 Totals 1.171 168.00 143.45
100.00
C. Results
[0133] i) Standard Polybutadiene with PCTP and DHTS TABLE-US-00021
Size (p inches) Size (off eq inches) Weight (grams) Comp Coeff
1.528 1.527 36.30 0.1030 0.8125 1.527 1.529 35.97 0.1040 0.8123
1.528 1.537 36.32 0.1023 0.8093 1.529 1.535 36.16 0.1049 0.8132
1.528 1.536 36.00 0.1058 0.8146 1.531 1.533 35.82 0.1052 0.8096
1.525 1.524 36.12 0.1024 0.8082 1.529 1.528 35.82 0.1019 0.8144
1.526 1.529 36.20 0.1027 0.8105 1.529 1.528 36.00 0.1017 0.8144
1.528 1.528 36.06 0.1040 0.8120 1.528 1.528 36.00 0.1037 0.8133
1.528 1.530 36.06 0.1035 0.8120 Nes factor = 915.5
[0134] ii) High Solution Viscosity/High Linearity Polybutadiene
with PCTP TABLE-US-00022 Size (p inches) Size (off eq inches)
Weight (grams) Comp Coeff 1.532 1.545 35.85 0.0975 0.8154 1.528
1.533 36.21 0.0977 0.8181 1.531 1.536 35.85 0.0980 0.8153 1.533
1.542 36.10 0.0996 0.8159 1.529 1.532 36.35 0.0978 0.8186 1.530
1.542 36.27 0.1001 0.8179 1.534 1.534 36.33 0.1010 0.8177 1.528
1.532 36.19 0.0993 0.8149 1.530 1.527 36.07 0.0970 0.8161 1.532
1.535 36.20 0.0985 0.8111 1.529 1.533 36.31 0.0974 0.8170 1.525
1.528 36.00 0.0987 0.8193 1.530 1.535 36.14 0.0986 0.8164 Nes
factor = 915
[0135] The results indicate that by adding hexamethylene
thiosulfate (DHTS) to conventional polybutadiene blends, similar
core performance results can be obtained (Nes factor=915.5) in
comparison to the use of a high solution viscosity/high linearity
polybutadiene without DHTS (Nes factor=915) (i.e., CB 10).
[0136] The invention has been described with reference to the
preferred embodiments. Obviously, modifications and alterations
will occur to others upon reading and understanding 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 claims and the
equivalents thereof.
* * * * *