Note: Descriptions are shown in the official language in which they were submitted.
WO 01/62348 1 PCT/USO1/04922
GAME BALL CENTER HAVING OUTER LAYER OF
INJECTION MOLDED IONOMER
Field of the Invention
The present invention relates generally to game balls and, more
particularly, to a ball having a resilient shell disposed about a relatively
low
density core.
Background of the Invention
Game balls such as baseballs and softballs are well known.
Typically, they are formed from a core of cork which is covered by a
winding of string or yarn wrapped about the core to provide strength and
resilience. Thereafter, a cover composed of a synthetic or natural leather
is disposed about the windings.
Prior art balls generally have a relatively short playing life. The cover
and windings may quickly become split from normal play and/or the ball
may become non-spherical such that playing characteristics are
unacceptable. Additionally, the prior art balls will soak up water when
exposed to wet, or even damp, conditions. When the ball becomes water
soaked, the weight of the ball is greatly increased, and the resilience of the
ball is decreased thereby reducing performance, e.g., feel off the bat and
sound or "crack" of the bat.
One particular standard measure of a property of a ball is that of the
ball's Coefficient of Restitution (COR). In determining the COR, a ball is
propelled against a standard surface at eighty (80) miles per hour, and the
speed of the rebound is determined. There are two standards set for balls,
one for restrictive flight balls and one for unrestrictive flight balls and
depending on league rules, e.g., given the age and abilities of the
participants, one or the other is chosen. Restrictive flight balls must have
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a COR of no more than 0.44, unrestrictive flight balls have no more than
0.48 and a COR higher than either of these will result in an unofficial ball,
not useable in official ball play.
Typically, prior art balls do not closely approach these standards on
maximum permissible COR and the problem becomes exacerbated when
the balls become water soaked.
Summary of the Invention
It is an object of the invention to provide a ball having an increased
durability with respect to the prior art.
It is another object to provide a ball with an improved coefficient of
restitution especially under wet conditions.
It is also an object of the present invention is to provide a ball having
and maintaining a desirable sound when the ball is struck by a bat.
Another object of the present invention is to provide a ball which is
formed in a relatively inexpensive manner and utilizes a relatively low cost
inner core.
These and other related aspects of the invention are achieved by
providing a game ball comprising a core, a thermoplastic shell intimately
encapsulating the core and preferably being composed of a foamed ionomer
and an outer cover being disposed about the shell and core. The core may
comprise either cork or polyurethane. The outer cover of the game ball
may comprise a synthetic leather or a natural leather. The game ball may
be either a softball or a baseball.
In another aspect of the present invention, the game ball comprises
a shell which comprises a plurality of layers, at least one of which
comprises an ionomer. Another of the layers may comprise an ionomer
which may have a filling material. For example, the filling material may
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comprise either a metal stearate or glass. The filling material may also
comprise microspheres which for example, may contain glass.
The present invention provides a ball which has greater durability
and an enhanced performance and sound relative to that of the prior art.
Brief Description of the Drawings
These and other objects and advantages of the invention will be
explained in greater detail with reference to the accompanying drawings,
in which:
Figure 1 is an elevational view of a game ball in accordance with an
embodiment of the present invention;
Figure 2 is a cross sectional view taken along line I of Figure 1;
Figure 3 is an enlarged partial cross sectional view of another
embodiment of the present invention; and
Figure 4 is a partial cross sectional view of a further embodiment of
the present invention.
Detailed Description of the Present Invention
A game ball in accordance with one embodiment of the present
invention is illustrated generally at 10 in Figure 1. The game ball, for
example a baseball or softball, comprises an outer covering 12 which may
be composed of a supple, flexible material such as leather or well known
leather substitute such as a synthetic leather. The cover 12 may be
stitched together by laces 14 in the case of a leather cover. In the case of
a synthetic cover, laces 14 may be formed or molded thereon for
maintaining the look and feel of the game ball 10.
As illustrated in Figure 2, the game ball 10 comprises a core 16 and
a shell 18 interposed between the core and the cover 12. The core 16 fills
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the shell 18 and assists in preventing collapsing of the shell when the ball
is hit by a bat. The core 16 may be composed of a relatively low density
material which is sufficiently resilient to withstand the flexing which occurs
during contact with a bat. Suitable materials include cork, kapok, feathers
or polyurethane, e.g., a polyurethane foam. The core 16 may also include
multiple layers of one or more of the foregoing materials.
In accordance with a feature of the present invention, the shell 18
is provided for increasing the durability and performance of the game ball
10. The shell 18 is preferably formed of a thermoplastic material such as,
for example, an ibnomer which is molded as a skin or the like over the
core. An ionomer which may be used in the practice of the present
invention is sold under the trademark SURLYN by the Du Pont Co.,
Wilmington, Delaware. The ionomer may, for example, contain an acrylate
ester-containing ionic copolymer in a weight percentage of 90 -100. The
thickness of the shell 18 may, for example, range on the order from about
0.0313 inches to about 0.500 inches.
In order to, e.g., reduce weight and/or decrease the stiffness of the
shell 18, the ionomer may be foamed and, as illustrated, the shell 18
includes gas pockets 20 disposed throughout the shell. It will be
appreciated that a suitable physical blowing agent or chemical blowing
agent may be employed during formation of the foamed ionomer. It will be
understood that the thickness of the shell 18 may be varied depending
upon, for example, the desired COR, sound and/or weight characteristics.
The shell 18 may also be composed of a blend of different thermoplastic
materials, e.g., an ionomer and another thermoplastic material.
During manufacture, the shell 18 is preferably formed through
injection molding or otherwise and, more preferably, foam molded about
the core 16 using suitable techniques in order to provide a sealed structure.
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Thereafter, the outer cover 12 may be mounted or molded over the shell
18.
Figure 3 illustrates another embodiment of a game ball in accordance
with the present invention, and a partial cross sectional view of the game
ball is generally illustrated at 10'. This embodiment of the present
invention varies from that of Figure 2, for example, in that the shell 18'
comprises a material composed of an ionomer and another material which
functions as a filler. It will be understood that the ionomer may also be
blended with another thermoplastic material as discussed above in addition
to employing a filler material. The ionomer may be filled with a material
such as a metal stearate, e.g. zinc stearate, which functions to improve
the moldability and processing of the ionomer and/or, in another example,
micro-spheres containing, e.g., glass or any other suitable low cost fillers.
Still another embodiment of the present invention is illustrated
generally at 10" in Figure 4. The game ball 10" is generally similar to
those illustrated with respect to Figures 2 and 3, excepting that a shell 18"
is provided which comprises multiple layers. In particular, two layers 18a"
and 18b" are illustrated, although, it will be understood that additional
layers may be employed. Layer 18a" may be composed of an ionomer or
an ionomer blended with another thermoplastic material and layer 18b"
may be composed of a filled ionomer with the filler being any of those
discussed above. It will be appreciated that the skilled artisan may vary
the particular properties and combinations of materials thereof in order to
better arrive at a game ball which is most suitable in weight, COR and/or
sound characteristics.
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While the present invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiments, it is to be understood that the present invention is not
limited to the disclosed embodiments. Rather, it is intended to cover all of
the various modifications and the equivalent arrangements included within
the spirit and scope of the appended claims.
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