U.S. patent application number 10/724952 was filed with the patent office on 2008-08-07 for game ball with urethane gum rubber surface.
This patent application is currently assigned to Spalding Sports Worldwide, Inc.. Invention is credited to Brian Feeney, Thomas J. Kennedy, R. Dennis Nesbitt.
Application Number | 20080188334 10/724952 |
Document ID | / |
Family ID | 23906207 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080188334 |
Kind Code |
A1 |
Feeney; Brian ; et
al. |
August 7, 2008 |
Game ball with urethane gum rubber surface
Abstract
A game ball having a highly durable cover exterior formed of a
urethane gum rubber compound. The urethane material of the cover
exterior is a cross-linked molded rubber material which provides
superior abrasion resistance compared to ball covers made from a
molded natural rubber.
Inventors: |
Feeney; Brian; (Enfield,
CT) ; Kennedy; Thomas J.; (Wilbraham, MA) ;
Nesbitt; R. Dennis; (Westfield, MA) |
Correspondence
Address: |
FAY SHARPE LLP
1100 SUPERIOR AVENUE, SEVENTH FLOOR
CLEVELAND
OH
44114
US
|
Assignee: |
Spalding Sports Worldwide,
Inc.
Chicopee
MA
|
Family ID: |
23906207 |
Appl. No.: |
10/724952 |
Filed: |
December 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09479985 |
Jan 10, 2000 |
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10724952 |
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Current U.S.
Class: |
473/605 |
Current CPC
Class: |
A63B 41/08 20130101;
A63B 45/00 20130101; A63B 2243/0037 20130101 |
Class at
Publication: |
473/605 |
International
Class: |
A63B 41/10 20060101
A63B041/10 |
Claims
1. A game ball comprising: an inflatable bladder; a layer of
windings disposed about said bladder; and a cover disposed about
said layer of windings, said cover including a vulcanized urethane
gum rubber layer, said urethane gum rubber layer having a thickness
of from 0.3 mm to 3.5 mm.
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
9. (canceled)
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. The game ball of claim 1, wherein the thickness of said
urethane gum rubber layer is from 0.9 mm to 2.7 mm.
24. The game ball of claim 1, wherein said urethane gum rubber
layer comprises a urethane gum rubber obtained from the
poly-addition of an isocyanate and a polyether; and said urethane
gum rubber is vulcanized through a sulfur-based cross-linking
reaction.
25. The game ball of claim 1, wherein said urethane gum rubber
layer comprises a urethane gum rubber obtained from the
poly-addition of a diphenylmethane diisocyanate and a C.sub.4
polyether; and said urethane gum rubber is vulcanized through a
sulfur-based cross-linking reaction.
26. The game ball of claim 1, wherein said cover further comprises
a vulcanization agent selected from the group consisting of sulfur,
mercaptobenzothiazole, dibenzothiazyl disulphide, zinc chloride
complex of dibenzothiazyl disulphide and mixtures thereof.
27. The game ball of claim 5, wherein said cover has a composition
comprising 50 to 100 parts of a urethane gum rubber and 2.5 to 12.0
parts of said vulcanization agent expressed parts by weight based
on 100 parts urethane.
28. The game ball of claim 6, wherein said composition further
comprises 5 to 50 parts of a reinforcing filler.
29. The game ball of claim 1, wherein said cover further includes
an inner layer overlayed by said urethane gum rubber layer.
30. The game ball of claim 8, wherein said inner layer is comprised
of cured natural rubber.
31. The game ball of claim 9, wherein said inner layer is foamed
and has a density within the range of 0.5 to 0.95 g/cm.sup.3.
32. The game ball of claim 8, wherein the thickness of said
urethane gum rubber layer is from 0.3 m to 1.9 mm.
33. The game ball of claim 11, wherein the thickness of said
urethane gum rubber layer is from 0.5 mm to 1.4 mm.
34. The game ball of claim 11, wherein the thickness of said inner
layer is from 0.1 mm to 1.6 mm.
35. The game ball of claim 1, wherein said urethane gum rubber
layer has a Shore A durometer hardness within the range of 45 to
85.
36. A game ball comprising: an inflatable bladder; a layer of
polymeric filaments wound over said bladder; and a cover molded
over said layer of filaments, said cover comprising a vulcanized
urethane gum rubber layer, wherein said urethane gum rubber
comprises a urethane gum rubber obtained from the poly-addition of
an isocyanate and a polyether; and said urethane gum rubber is
vulcanized through a sulfur-based cross-linking reaction.
37. The game ball of claim 15, wherein said cover consists
essentially of said urethane gum rubber layer.
38. The game ball of claim 15, wherein said cover further comprises
a vulcanized natural rubber layer, said natural rubber layer
positioned between said layer of filaments and said vulcanized
urethane gum rubber layer.
39. The game ball of claim 17, wherein said cover consists
essentially of said urethane gum rubber layer overlying said
natural rubber layer.
40. The game ball of claim 17, wherein said inner layer of said
cover is foamed to attain a density of 0.5 to 0.95 g/cm.sup.3.
41. The game ball of claim 17, wherein said inner layer has a
thickness in the range of 0.01-1.16 mm and said urethane gum rubber
layer has a thickness in the range of 0.3-1.9 mm.
42. A basketball comprising: an inflatable bladder; a layer of
polymeric filaments overlaying said bladder; and a multi-layered
cover overlying said layer of filaments, said cover comprising a
vulcanized natural rubber inner layer with a density of at least
0.8 g/cm.sup.3 overlying said layer of filaments and a vulcanized
urethane rubber exterior layer with a density of at least 0.8
g/cm.sup.3 overlying said inner layer, said exterior layer having a
higher durometer hardness and greater abrasion resistance than said
inner layer.
43. The basketball of claim 21, wherein the thickness of said
exterior layer is from 0.3 mm to 1.9 mm.
44. The basketball of claim 22, wherein the thickness of said
exterior layer is from 0.5 mm to 1.4 mm.
45. The basketball of claim 21, wherein the thickness of said inner
layer is from 0.1 mm to 1.6 mm.
46. The basketball of claim 24, wherein the thickness of said inner
layer is from 0.6 mm to 1.4 mm.
47. A method for making a game ball, comprising: providing a core;
providing urethane gum rubber resin obtained from the poly-addition
of an isocyanate and a polyether; mixing a vulcanized agent with
said urethane gum rubber resin to create a urethane gum rubber;
molding said urethane gum rubber over said core; and vulcanizing
said urethane gum rubber through a sulfur-based cross-linking
reaction.
48. The method of claim 26, wherein said urethane gum rubber resin
is obtained from the poly-addition of a diphenylmethane
diisocyanate and a C.sub.4 polyether.
49. The method of claim 26, wherein said vulcanization agent is
selected from the group consisting of sulfur,
mercaptobenzothiazole, dibenzothiazyl disulphide, zinc chloride
complex of dibenzothiazyl disulphide and mixtures thereof.
50. The method of claim 26, further comprising the step of molding
a rubber inner layer over said core and wherein the step of molding
said urethane gum rubber over said core comprises molding said
urethane gum rubber over said rubber inner layer.
51. The method of claim 29, wherein said step of molding a rubber
inner layer over said core comprises foaming said inner layer to a
density within the range of 0.5-0.95 g/cm.sup.3.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to game balls and
more particularly is directed to game balls having a urethane gum
rubber surface which provides for improved durability of the
ball.
BACKGROUND OF THE INVENTION
[0002] Traditionally, game balls are made with an outer cover of
leather. With a sport such as basketball, when played exclusively
in a gymnasium on a finished wooden floor, or football, which is
played on a grass covered field, the durability of a leather
covered game ball is not a critical factor. However, when these and
other sports are played on a paved surface such as is present in
playgrounds, residential driveways, parking lots, or even in the
street, the leather cover of the game ball wears excessively from
contact with the abrasive paved playing surface.
[0003] The game ball industry has developed balls featuring covers
formed from molded materials such as rubber or polyvinyl chloride
(PVC) to improve ball wear. In addition, synthetic leather covers
have been developed which closely simulate the appearance and feel
of a natural leather cover, while providing greater durability than
could be provided by natural leather.
[0004] Game balls which have covers made of molded natural rubber
or PVC are often formed with a pebbled surface texture resembling a
pebble-grained leather. When such balls are used on a paved playing
surface the pebble texture tends to wear away leaving the surface
of the ball smooth, slick and difficult for the player to handle. A
small amount of dust on either the hands of the player or on the
surface of the worn ball may dramatically increase the slipperiness
of the ball. Likewise, perspiration on the hands of the player or
water on the surface of the worn ball increase the slipperiness of
the ball as well.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to provide a game ball
with improved wear resistance.
[0006] Another object of the present invention is to provide a game
ball with improved wear resistance and with play performance
characteristics which are similar to the play performance
characteristics of a game ball with a natural rubber cover.
[0007] These and related objects are achieved by providing a game
ball with a cover formed of a urethane gum rubber composition. The
urethane gum rubber is a raw rubber, based on polyurethane, which
is subjected to a cross-linking process (vulcanization) during and
after forming operations. The cured urethane rubber composition has
a cross-linked structure similar to that of vulcanized natural
rubber, but exhibits abrasion resistance many times greater than
natural rubber compounds. When used in the cover of a game ball the
ball exhibits very high durability with a high resistance to
abrasion and wear as experienced in normal use.
[0008] The cover of the ball is formed by molding the urethane gum
rubber in place over the substructure of the ball and subjecting
the molded ball to conditions to promote the cure and cross-linking
of the urethane gum rubber. The compositions of the cover
optionally include other materials, such as fillers, coloring
pigments or dyes, cross-linking promoters, processing aids and cure
accelerators.
[0009] A urethane gum rubber cover may be applied to any game ball.
However, such a cover has particular utility when used in
connection with basketballs, footballs, softballs, baseballs, and
generic play balls for use on paved surfaces. It is envisioned that
other game balls may advantageously use the urethane gum rubber
compositions for their respective covers.
[0010] The invention accordingly comprises the several steps and
the relation of one or more of such steps with respect to the
others and the article possessing the features, properties, and
relation of elements as exemplified in the following detail
disclosure.
DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a sectional view of the cover of a game ball made
according to the invention.
[0012] FIG. 2 is a sectional view of the cover of a game ball made
according to a second embodiment of the invention in which the
cover has multiple layers.
[0013] FIG. 3 is a view of a basketball, partially broken away and
partially in section, according to the second embodiment of the
invention which features a multiple layer covering.
DETAILED DESCRIPTION OF THE INVENTION
[0014] For clarity of description and ease of understanding, the
invention will be described in connection with basketballs. It will
be understood that other game balls including balls with various
core structures which may include solid cores, hollow cores, wound
cores, air-filled bladders and even air filled balls which have no
bladder can advantageously employ the features of the present
invention. Furthermore, in the figures similar structures in the
several drawings will be identified with the same numbers.
[0015] With reference to FIG. 1, the basketball 10 includes a
bladder 12 for holding air, a reinforcing layer of monofilament
windings 14 which wrap around the bladder 12 and help the ball
maintain its shape, and a cover layer 16 of a urethane gum rubber
which surrounds and encloses the winding wrapped bladder. The
bladder 12 is typically made of, for example, a butyl rubber
composition including halo-butyl rubber (chloro or bromo-butyl
rubber), or other similar resilient, stretchable material for
holding air. The bladder 12 has a generally spherical shape and is
equipped with a valve or other structure (not shown) for permitting
air under pressure to be introduced to the interior of the bladder
12 for inflation and pressurization.
[0016] The wound reinforcing layer 14 is typically formed of
monofilaments of polyester and/or nylon and is wrapped around the
bladder 12 in either a pre-determined pattern or a random fashion
to help the ball 10 retain spherical shape under typically
inflation pressure and under the stresses of use. The windings 14
are coated with an adhesive which allows them to adhere to the
bladder 12 and also to each other to ease the winding process. The
bladder 12 is ordinarily fully or partially pressurized to maintain
a spherical shape while the wrappings are applied. In addition, the
bladder 12 may be cooled to stiffen and stabilize the material of
the bladder to further ease winding of the reinforcing layer.
[0017] The cover 16 forms the exterior surface of the ball. The
cover 16 in the present invention is formed of a urethane gum
rubber composition which is molded in place over the monofilament
wrapped bladder and cured, preferably in a spherical mold with the
application of heat and pressure to promote the cure and
cross-linking of the urethane cover material.
[0018] In FIG. 2 a second embodiment of the invention is shown with
the ball 20 featuring a bladder 12 covered by a layer of windings
14, over which a multiple layer cover 22 is formed. The multiple
layer cover 22 features an inner or first layer 24 which surrounds
and encloses the bladder 12 and wound layer 14, and an outer or
second cover layer 26 which surrounds and encloses the first cover
layer 24 and defines the ball exterior surface 18. The first cover
layer 24 is formed of a natural rubbers while the outer cover layer
26 is formed of a urethane gum rubber composition.
[0019] In FIG. 3 a basketball with a multiple layer cover is shown
partially cut away. The ball 30 includes a bladder 12 covered with
a layer of windings 14 which is enclosed by an inner cover layer 24
of a natural rubber composition, the whole being enclosed and
enveloped within an outer cover layer 26 of urethane gum
rubber.
[0020] The use of a multiple layer cover combining a layer of
natural rubber with a layer of urethane gum rubber in the cover
reduces the total amount of urethane gum rubber required in a ball
of the present invention. At present market prices, urethane gum
rubber materials are quite expensive. Creating a cover with a
reduced amount of urethane gum rubber is of particular interest in
controlling the cost of a game ball. By reducing the thickness of
the urethane gum rubber used in the cover of the ball and adding a
layer of natural rubber, the desirable durability and long-wearing
properties are retained while the total expense of the materials
from which the ball is made are reduced. The urethane gum rubber
used in the cover of the invention is a raw rubber material based
on polyurethane which can be processed using conventional machinery
intended for processing natural rubber compounds. Like a natural
rubber composition, the urethane gum rubber is shaped and then
subjected to a cross-linking process (vulcanization).
[0021] The cover of the ball of the present invention may be molded
to include a textured outer surface 18 for improving the grip and
feel of the ball. It will be appreciated that the surface 18 of a
basketball can be molded with a surface texture simulating the
pebbled texture of pebble-grained leather or any other texture as
desired. Other surface detail including the manufacturer's name,
trademarks, model numbers, inflation instructions, ball detailing
such as simulated lacing or stitching, and graphics can also be
molded into the surface of the ball.
[0022] In terms of physical properties, once a urethane gum rubber
is cross-linked and cured it exhibits high tear resistance, high
elongation at break, high rebound resilience, and depending on the
composition, a Shore A hardness of about 45-85. The cross-linked
urethane gum rubber also has excellent resistance to degradation
from exposure to ultra-violet light, oxygen, and ozone. What is of
greatest interest in the present invention is the high degree of
abrasion resistance offered by the urethane gum rubber.
[0023] One particular urethane gum rubber highly suitable for use
in this invention is commercially available from Rhein Chemie
Corporation, Trenton, N.J., and is commercially available as UREPAN
50EL06G. This particular urethane material is the poly-addition
product made from diphenylmethane diisocyanate and a C.sub.4
polyether. According to the manufacturer, UREPAN 50EL06G may be
processed using standard rubber industry processing techniques and
equipment without any restrictions. It will be appreciated by the
practitioner of skill in the art that other UREPAN materials and
similar materials available from other chemical manufacturers, may
be selected according to their physical properties for the desired
game ball application. The urethane gum rubber of the present
invention is mixed with other materials for processing into a game
ball cover. In general, these materials include vulcanizing agents
for promoting the cross-linking of the urethane gum rubber and
various other components including fillers, coloring materials, and
materials to improve processing.
[0024] The vulcanizing agents act as cross-linking agents and as
cure accelerators. The use of sulfur plus mercapto accelerators has
proven to be favorable for use as vulcanizing agents in urethane
gum rubber resin compositions. Zinc stearate may be used as a
coactivator. Therefore, combinations of sulfur,
mercaptobenzothiazole (MBT), dibenzothiazyl disulphide (MBTS),
complexes of zinc chloride and dibenzothiazyl disulphide (RHENOCURE
AUR available from Rhein Chemie Corp., Trenton, N.J.) and mixtures
thereof may be used as cross-linking agents and cure accelerators
in urethane gum rubber resin compositions.
[0025] A general formula setting forth the amounts of various
components and additives suitable for making a game ball cover is
presented in Table 1 below.
TABLE-US-00001 TABLE 1 URETHANE GUM RUBBER COMPOSITION General
Formula Ingredient Parts by Weight urethane 50-100 sulfur 1-4
reinforcing filler 5-50 zinc stearate 0.25-2.0 curing agent 0.5-2.0
cure accelerator(s) 1.0-6.0 coloring pigment(s) 0-5 processing
promoter 1.0-5.0 dispersing and tackifying resin 0.5-3.0
[0026] The process of manufacturing a game ball of the present
invention is generally similar to that used in manufacturing a game
ball having a natural rubber cover. In the case of a game ball
having a cover 16 comprising a single layer of urethane gum rubber,
a bladder 12 of butyl rubber is manufactured by conventional
methods, such as by parison blow-molding or by blow-molding two
parallel sheets of uncured butyl rubber in a spherical mold.
Typically, a valve is molded into the bladder 12 when the bladder
is formed.
[0027] The bladder 12 is inflated to an appropriate pressure to
stabilize its spherical shape and monofilaments of polyester and/or
nylon are then wrapped around the bladder 12 to create the winding
layer 14. To cause the windings to adhere to the bladder and to
each other, and thus simplify the winding process, the filaments
are lightly coated with an adhesive (not shown) compatible with the
materials of the bladder 12, the windings, and the cover 16. As the
monofilaments are wrapped in place around the bladder 12 the
adhesive holds them in place and prevents them from unraveling.
[0028] A batch of urethane gum rubber is prepared having a general
composition as set forth in Table 1. The components of the
composition are mixed using standard rubber processing equipment,
such as a Banbury mixer, to thoroughly combine the ingredients. A
pliable, moldable dough-like mass is produced which can
subsequently be molded and cured. For the cover of a ball, such as
a basketball, the dough-like mass of uncured urethane gum rubber is
formed into a sheet such as by passing it through the rollers of a
calendaring machine. The uncured sheet is cut to an appropriate
size and shape for lining the interior surface of a hemispherical
ball mold. For a basketball, the sheet can be cut into
double-tapered panels or simple strips, for example, and laid in
each half of the ball mold to completely cover the mold surface. A
mold may feature a vacuum system to hold the panels in place in the
mold or, alternately, a light adhesive may be used to hold the
panels in place. Typically, the panels or pieces of uncured sheet
of urethane gum rubber are overlapped at their edges to ensure the
structural integrity of the molded cover. Alternatively, the
urethane gum rubber can be preformed into a hollow hemispherical
shape ending at an equator line. Two urethane hemispheres are then
placed in opposition within the mold with their equator lines
facing.
[0029] The interior surface of the ball mold may be engraved or
tooled to impart a surface texture to the cover of the finished
ball. Also, simulated stitching, lacing, seams or panel lines may
be added to the mold surface, along with manufacturers' names,
model names and numbers, autographs of sport figures and graphic
designs, for molding into the ball cover.
[0030] A bladder 12 and winding layer 14 subunit is placed into the
mold lined with urethane cover material and the mold is closed
around the subunit. The bladder is inflated to force the subunit
into full contact with the urethane material lining the interior of
the mold cavity. Heat and pressure is applied to the mold to cause
the raw urethane gum rubber to flow into and around the
monofilaments of the winding layer and to assume the shape and
texture imparted by the tooled mold inner surface. The heat and
pressure also causes the urethane material to cross-link and cure,
firmly bonding the cover and subunit into a unitary basketball and
permanently creating the textured exterior surface of the ball. At
the end of the time necessary to attain the desired level of
cross-linking, the completed ball is removed from the mold and
allowed to cool. Any flash or mold marks left on the cover of the
finished ball may be buffed out or otherwise removed. The ball may
then be decorated through the application of paint, decals, and
other graphics or decorations.
[0031] The game ball 20 of the present invention which possesses a
multi-layer cover 22 may be made according to a process similar to
that described above. A layer of raw urethane gum rubber sheet is
placed in contact with the mold halves. A layer of raw natural
rubber sheet is placed in contact with the urethane gum rubber
layer. The bladder and winding layer subunit is placed within the
mold, the mold is closed and the bladder inflated. Heat and
pressure is applied and both the natural rubber and urethane gum
rubber flow and are cured within the mold. Naturally, one or both
of the natural and urethane rubber layers could also be in the form
of hollow hemispheres which are layered in opposition within the
mold.
[0032] The ball of the invention may also be manufactured using the
carcass and panel method as described in U.S. Pat. No. 3,119,618.
This method is particularly suited for the manufacture of
basketballs. Following this method a ball carcass which
encapsulates the bladder and windings can be molded from a natural
rubber compound. The carcass is formed with protruding channels
which provide assistance in locating the cover panels in position
on the ball. The cover panels are formed from a urethane gum rubber
composition and cured in a mold which provides cover panels of the
exact size and shape need to fit between the channels of the
carcass. The cured panels are glued in place on the carcass with an
adhesive appropriate for the carcass and cover materials, the ball
is given a final clean-up to remove manufacturing marks, and detail
or decoration are added, as needed.
[0033] When a multi-layered cover is to be made special care must
be taken in selecting and preparing the materials used in the cover
and also special care must be taken in the subsequent cross-linking
process. It is well known that natural rubber cross-links at a much
faster rate than the urethane gum rubber. For example, a typical
natural gum rubber composition will typically vulcanize within 5
minutes upon application of 150.degree. C. In contrast, a urethane
gum rubber as used in the present invention may take up to 15
minutes to achieve a desired level of cross-linking. It is further
known that exposing the natural rubber to the amount of heat
necessary to achieve proper cross-linking for the urethane gum
rubber may damage the natural rubber. Conversely, exposing the
urethane gum rubber to the amount of heat necessary to cause
cross-linking of the natural rubber will leave the urethane gum
rubber under cured. To accommodate the disparate cure rates of the
natural rubber and the urethane gum rubber the inventors have found
that reduced amounts of accelerators in the natural rubber
composition may be used.
[0034] It may be desirable for certain game ball applications to
produce a softer cover material. As the urethane gum rubber of the
cover is typically rather hard, the inventors have found that
foaming the natural rubber layer of the multi-layered cover
provides the finished ball with an appropriate level of cover
softness. In the case of a basketball cover, a foam rubber density
in the range of 0.5 to 0.95 grams/cubic centimeter (g/cm.sup.3)
provides a ball with good feel and playability.
[0035] In a game ball with a single layer cover, the thickness of
the urethane gum rubber layer ranges from 0.3 to 3.5 mm, more
preferably from 0.9 to 2.7 mm and optimally is about 1.9 mm. In a
game ball with a multiple layer cover, the thickness of the inner
natural rubber layer ranges from 0.1 to 1.6 mm, more preferably
from 0.6 to 1.4 mm and is optimally about 1.1 mm. The outer
urethane gum rubber layer overlying the inner natural rubber layer
ranges from 0.3 to 1.9 mm, more preferably from 0.5 to 1.4 mm and
is optimally about 0.8 mm. Naturally, when a carcass with
protruding channels is used, the thickness of the inner natural
rubber layer will be greater in the area of the channels.
[0036] A batch of urethane gum rubber was prepared according to the
formulation found in Table 2 below. This composition is identified
as STOCK EXAMPLE 1 (Stock Ex. 1).
TABLE-US-00002 TABLE 2 STOCK EXAMPLE 1 - URETHANE GUM RUBBER
COMPOSITION Ingredient Parts by Weight UREPAN 50ELO6G.sup.1
urethane rubber resin 100.00 sulfur 1.50 CABOSIL.sup.2 reinforcing
filler 40.00 zinc stearate 0.50 RHENOCURE AUR.sup.3 curing agent
1.00 ALTAX (MBTS).sup.4 cure accelerator 4.00 CAPTAX (MBT).sup.5
cure accelerator 2.00 ORANGE MASTER BATCH.sup.6 coloring 3.50
TiO.sub.2 coloring pigment 2.00 AFLUX 12.sup.7 processing promoter
1.00 RHENOSIN TM90.sup.8 processing promoter 4.00 TOTAL 159.5
.sup.1UREPAN 50ELO6G is a urethane rubber resin commercially
available from Rhein Chemie Corp., Trenton, New Jersey.
.sup.2CABOSIL is a fumed silica reinforcing filler commercially
available from Cabot Corp., Atlanta, Georgia. .sup.3RHENOCURE AUR
is a curing agent for sulphur cross-linkable polyurethane rubbers
and is commercially available from Rhein Chemie Corp., Trenton, New
Jersey. .sup.4ALTAX is an MBTS cure accelerator commercially
available from R. T. Vanderbilt, Norwalk, Connecticut. .sup.5CAPTAX
is an MBT cure accelerator commercially available from R. T.
Vanderbilt, Norwalk, Connecticut. .sup.6ORANGE MASTER BATCH is an
orange colored pigment master batch commercially available from
Disco Inc., Ringwood, New Jersey. .sup.7AFLUX 12 is a processing
promoter for synthetic rubber compounds and is commercially
available from Rhein Chemie Corp. .sup.8RHENOSIN TM90 is a
processing promoter which improves the distribution of fillers
within the rubber composition and is commercially available from
Rhein Chemie Corp.
[0037] The ingredients were mixed in a Banbury-type mixer to
completely mix the ingredients and obtain a batch of stock
identified as Stock Example 1. It will be appreciated that the
urethane gum rubber of the invention may be mixed and processed
using conventional rubber making equipment and techniques. The
uncured mixture was then passed through a calendaring machine or a
2 roll mill to produce a sheet of uncured urethane gum rubber. The
sheet was cut into several pieces each sized to fit a plaque mold
and the pieces were cured in an electric press under various
conditions which are outlined below. The samples were tested to
determine their physical properties.
STOCK EX. 1-A
[0038] A sample Stock Example 1 was placed in a mold preheated and
maintained at a temperature of 150.degree. C. The material remained
in the hot mold for 10 minutes under 7 tons of pressure to form a
plaque and was removed while hot. This plaque was tested and found
to hive a Shore A hardness of 77.
STOCK EX. 1-B
[0039] A plaque was prepared as in Example-1A above, with the
plaque remaining in the hot mold for 20 minutes. This plaque was
tested and found to have a Shore A hardness of 77.
STOCK EX. 1-C
[0040] A plaque was prepared as in Example 1-A above, with the
plaque remaining in the hot mold for 30 minutes. This plaque was
tested and found to have a Shore A hardness of 78.
COMPARATIVE EXAMPLE 1
[0041] A batch of natural rubber cover stock having a composition
as set forth in Table 3 below was also prepared. This composition
is identified as COMPARATIVE EXAMPLE 1 (Comp. Ex. 1).
TABLE-US-00003 TABLE 3 COMPARATIVE EXAMPLE 1 - NATURAL RUBBER
COMPOSITION Ingredient Parts by Weight 60 CV.sup.1 Malaysian
natural rubber resin 59.00 ANDREZ 8000.sup.2 high styrene resin
22.00 CARIFLEX BR-1220.sup.3 polybutadiene 19.00 VERFLAKE
(CaCO.sub.3).sup.4 filler 60.00 HISIL 233.sup.5 reinforcing filler
18.50 CIRCO.sup.6 light oil processing oil 5.00 ZnO activator 3.30
stearic acid activator 2.00 DEG diethylene glycol activator 1.00
CUMAR.sup.7 resin plasticizer 2.20 VANAX 1290.sup.8 antioxidant
2.20 ORANGE MASTER BATCH coloring pigment 3.50 sulfur 1.90 CAPTAX
(MBT) cure accelerator .78 ALTAX (MBTS) cure accelerator .24
unads.sup.9 cure accelerator .50 m. tuads.sup.10 vulcanization
accelerator 1.00 Total 202.12 .sup.1SMR 60 CV is a natural butyl
resin obtained from Malaysian rubber trees and is commercially
available from Muehlstein, Leominster, Massachusetts. .sup.2ANDREZ
8000 is a commercially available from high styrene/butadiene resin
commercially available from Anderson Development, Adrian, Michigan.
.sup.3CARIFLEX B2-1220 is a polybutadiene commercially available
from Muehlstein, Norwalk, Connecticut .sup.4VERFLAKE is a calcium
carbonate filler commercially available from Hampden Color &
Chemical, Springfield, Massachusetts. .sup.5HISIL 233 is a fumed
silica reinforcing filler commercially available from PPG
Industries, Pittsburgh, Pennsylvania .sup.6CIRCO light oil is a
processing oil commercially available from Sun Chemical,
Cincinnati, Ohio. .sup.7CUMAR is a plasticizer/softener
commercially available from Neville Chemical, Pittsburgh,
Pennsylvania. .sup.8VANAX 1290 antioxidant commercially available
from R. T. Vanderbilt. .sup.9unads is a tetramethyl thiuram
monusulfide vulcanization accelerator commercially available from
R. T. Vanderbilt, Norwalk, Connecticut. .sup.10m. tuads is a methyl
tetramethyl thiuram disulfide vulcanization accelerator
commercially available from R. T. Vanderbilt, Norwalk,
Connecticut.
[0042] The natural rubber composition was mixed in a Banbury mixer,
formed into a sheet on a 2 roll mill and pieces of the sheet were
cut to fit a plaque mold. The pieces were then cured in an electric
press under various conditions as outlined below. Tests were
conducted to determine their physical properties.
COMP. EX. 1-A
[0043] A sample of the batch of stock identified as Comp. Ex. 1 was
placed in a mold preheated and maintained at a temperature of
140.degree. C. The material remained in the hot mold for 10 minutes
to form a plaque and then was removed while hot. This plaque was
tested and found to have a Shore A hardness of 70.
COMP. EX. 1-B
[0044] A plaque was prepared as in Comp. Ex. 1-A above, with the
plaque remaining in the hot mold for 20 minutes. This plaque was
tested and found to have a Shore A hardness of 77.
COMP. EX. 1-C
[0045] A plaque was prepared as in Comp. Ex. 1-A above, with the
plaque remaining in the hot mold for 30 minutes. This plaque was
tested and found to have a Shore A hardness of 78.
[0046] Comparative testing was carried out on samples of the
urethane gum rubber and the natural rubber of the control stock
using a Taber abrasion testing machine following the methods
outlined in ASTM F 510-78. The results of the Taber abrasion test
are reported below in Table 4.
TABLE-US-00004 TABLE 4 ABRASION TESTING (TABER) Mass in grams of
amount abraded after 1000 cycles using H-18 "GREY WHEEL" Material
1.sup.st RUN 2.sup.nd RUN Comp. Ex. 1-A, natural rubber, 0.84 1.03
10 min. cure time Stock Ex. 1-A, urethane gum 0.11 0.12 rubber, 10
min. cure time Comp. Ex. 1-B, natural rubber, 1.08 1.04 20 min.
cure time Stock Ex. 1-B, urethane gum 0.11 0.10 rubber, 20 min.
cure time Comp. Ex. 1-C, natural rubber, 1.11 1.08 30 min. cure
time Stock Ex. 1-C, urethane gum 0.11 0.10 rubber, 30 min. cure
time
[0047] In each of the abrasion test runs it was found that the
polyurethane rubber provided substantially greater resistance to
abrasion than did natural rubber. It will be recalled that natural
rubber cures more quickly than urethane rubber and consequently one
might expect natural rubber to have greater abrasion resistance
than urethane rubber at the shorter cure times. Surprisingly, the
urethane rubber exhibits higher abrasion resistance than natural
rubber at every cure time tested. It is also projected that the
urethane rubber likewise would perform superior to the natural
rubber at every cross-link density. It will be appreciated that
improved abrasion resistance translates directly into longer ball
life and retention of molded surface texture.
[0048] A ball made according to the present invention with a
polyurethane rubber cover was tested against several commercially
available balls in a bounce test. The ball made according to the
present invention was designated Example 2. In the bounce test each
ball was propelled from a series of rotating wheels (in a manner
similar to batting practice machines used to pitch baseballs) at an
angled barrier comprising a new, cross-hatched steel bounce plate.
The ball bounces off the angled barrier and is directed into a net
where the energy of the rebounding ball is dissipated. A return
ramp in the mechanism automatically returns the ball to the wheels
for repeated firing against the angled barrier. The firing is
continued until the ball has been fired against the barrier 10,000
times; each impact with the angled barrier being counted as a
single bounce.
[0049] Prior to the testing each ball was measured to determine the
initial circumference (size) of the ball in inches, initial weight
in grams, durometer hardness (using a Type "O" gauge from Rex Gauge
Company, 1250 Busch Parkway, Buffalo Grove, Ill.), and out of round
measurement or "O/R". Out of round measurement is tested by placing
a ball on a roller stand. A dial indicator is placed against the
ball outside surface and the gauge is set to read zero. The ball is
rotated on the roller stand 360 degrees and the high and low
readings on the gauge are recorded. The ball is repositioned a
total of three times and the high and low measurements are
averaged. The differences between the high and low readings
represent the out of round measurement.
[0050] After 10,000 bounces the size, weight, durometer hardness
and O/R measurements were taken again. In addition, the change in
weight of each ball was determined. The data accumulated is
reported in Table 5, below.
TABLE-US-00005 TABLE 5 BOUNCE AND ABRASION TESTING OF BASKETBALLS
Measurements After 10,000 Bounces Ball Ball Initial Measurements
Change Mfg. Model Dur. Size O/R Wt. Dur. Size O/R Wt. in Wt.
Example 2 72 30.13 0.087 596.9 72 30.31 0.125 593.7 3.2 Wilson Jet
Extreme 56 29.88 0.116 598.3 54 30 0.160 594.5 3.8 Vega NBA 70
29.63 0.077 593.5 67 29.75 0.116 578.7 14.8 Ultimate Rawlings RR1
73 29.63 0.028 615.2 70 30.00 0.109 598.6 16.6 Urax ZR 58 29.75
0.049 596.2 55 30.06 0.182 578.8 17.4 Cushion Urax Kobe 71 29.75
0.046 595.1 67 30.00 0.187 573.3 21.8 Nike NSB 1000 70 29.56 0.050
621.6 70 29.63 0.085 586.4 35.2 Weight Measurements (wt.) are given
in grams. Size refers to the circumference of the ball measured in
inches.
[0051] As shown in Table 5, the ball made according to the present
invention, Example 2, showed the lowest change in weight due to
abrasion incurred in the bounce test. The durometer hardness
remained unchanged before and after the test, a performance which
was only equaled by the Nike "NSB 1000" ball. The Example 2 ball
showed a slight increase in size (0.18 inch) due to the repeated
impacts. This is well within acceptable limits and less than the
Urax "ZR Cushion" and Urax "Kobe" balls.
[0052] As will be apparent to those skilled in the art, various
modifications and adaptations will become readily apparent without
departure from the spirit and scope of the invention.
* * * * *