Note: Descriptions are shown in the official language in which they were submitted.
~ CA 02214771 1997-09-0~
Ftl~E, F~a ~3 Tl~l~; A~Y~
T~T I~IA~SL~TION
Use of a Composite Material to Produce Sports Balls or as Shoe Upper Material
The invention relates to the use of a composite material to produce sports balls or shoe upper
material. The composite material comprises multiple layers, whereby an abrasion-resistant
plastic layer is provided as the outermost layer and a layer of spun-fiber nonwoven material
is provided as an inner layer.
The use of composite materials to produce sports balls is known, whereby an abrasion-resistant
plastic coating is provided as the outermost layer and a layer of resilient plastic, woven fabric,
felt or nonwoven material is provided as the interior layer; as applicable, several such layers
can be provided (c~ DE 27 23 625-C2, DE-U-18 72 725, DE 24 56 071-Al, DE-U-75 02 670,
EP-03 05 595-Al, DE-U-82 07 404.6, DE-29 50 620-Al). The essential problem in using
materials of this type for sports balls is that shape stability cannot be attained in the cover
because of strong internal pressure from an interior rubber bladder inflated with pressurized
air. Without special l~min ~tion on the innermost layer, balls of this type fail to attain perfect
roundness, while precision-made balls become unstable and lose their roundness over time.
This is due to the inadequate tensile stability of the inner layer or layers, particularly when
nonwoven materials or felts are used and/or when woven fabric backings are used and there
is directionally-dependent stretching.
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Until now, it has therefore been necessary, when such covers are used, to provide multiple
intermediate layers of cotton, viscose, polyamide or polyester, with the individual fabrics being
expensively laid at a 45~ angle to each other to attain multi-directional stability or special
sateen binding being provided to strengthen the fabric itself.
It is not possible, however, to attain ideal isotropic stretching of the supporting and
strengthening layers in this manner.
The object of the invention is to propose a composite material with which the type of sports
balls that are composed of several pieces sewn or bonded together and enclose an interior
rubber bladder attain exact ball-shaped roundness at the prescribed internal pressure of the
rubber bladder, and do not become unstable under heavy stress, and have long-lasting soft
elastic resilience.
According to the invention, this object is ~tt~ine~l by means of the features of the main claim
and furthered by the features of the subclaims.
rrhe outer layer is made of an abrasion-resistant plastic, such as polyurethane, silicone rubber,
polyvinyl chloride, polyethylene, polypropylene or polyacrylate, or of rubber latex. Because
the outermost plastic layer, which determines appearance, strength and resilience, is joined to
a second layer of spun-fiber nonwoven material that has uniform stretching and tearing
strength in all directions, regularity is achieved in the composite.
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Because of the uniformly low stretching and high tearing strength in all directions of the spun-
fiber nonwoven material of the second layer, the elastic material of the outer layer is able to
expand in a controlled and absolutely uniform fashion due to the internal pressure from the
inflated ball. Because of this corset, the roundness and precision of the balls are m~int~ined
in an absolutely shape-stable manner, and the material of the outer layer cannot warp or
expand irregularly. A further advantage of using such materials is ease of processing, because
the materials can be cut and sewed with clean edges.
Spun-fiber nonwoven materials have been known for a long time and are used in vehicle
construction, carpet manufacture, building and civil engineering, overhead trains, filter
technology, the electronics industry, rug manufacture, garden construction and agriculture.
Their high tearing strength, shock resistance, dimensional stability, temperature stability,
permeability, consistency and thermal deformability make them suitable for all of these uses.
To produce such nonwoven materials, such fiber-forming plastics as polyamide, polyester,
polyolefines, PVC and poly~ylelle are spun and the thin threads are deposited endlessly in
random orientation and then bonded into layers; bonding is done either by bonding the
crossing points of the threads with pressure and heat or by spraying a binding agent onto the
threads to cement them (cf~ DE 13 03 891-Bl).
Preferably, an inner or third layer of a suitable staple-fiber nonwoven material is provided,
which establishes a pressure equilibrium between the rubber bladder filled with pressurized air
and the outer cover and
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also damps the resilience to a certain extent, so that the cover behaves like a leather cover.
The invention provides the substantial advantage that sports balls manufactured with such
material attain optimal roundness under the heaviest stress. Stability is increased by the direct
application of the outer coating in plastic form to the second layer of spun-fiber nonwoven
material, so that an intimate connection can be achieved between the two layers. In addition,
sports balls with this structure can be inflated at higher pressure without losing their shape and
precision. Given a sufficiently strong nonwoven maf~erial, the seams of the balls last longer
than average and do not rip. Balls produced with this structure maintain their shape stability
even over long-term use because, thanks to the completely isotropic stretching of the
nonwoven material, they cannot warp or become unround.
When the aforementioned composite materials are used for sports balls, vulr~ni7~fion is
especially effective in optimi7.ing the bouncing behavior of the balls and is therefore especially
preferred. This realization is based on the fact that such composite materials become sluggish
and stiff when bonded in a self-linking manner or with latex, for example. It has thus been
found that self-linking nonwoven materials are not suitable for use as high-quality ball
material, because sports balls produced from such fabrics have no liveliness and display poor
bouncing behavior, which in practice is unacceptable in sports. The reason for this negative
bouncing effect is that
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in self-linking systems, the fibers of the nonwoven material are cemented stiffly and
inelastically with resins.
In contrast, vulc~ni7~tion even makes it possible, depending on needs and requirements, to
systematically attain different elasticity values and degrees of hardness in the nonwoven
substrate. Vulc~ni7~tion creates a soft rubber that is highly resistant to heat and cold. The
latex is vulcanized with the nonwoven material at 140~ -- in contrast to coagulation, which is
based on a temperature between 37~ and 65~.
The temperature of 140~ should not be exceeded during vul~ni7~tion, because the quality of
the vulcanized substrate would be lost and the nonwoven material would become hard and
brittle.
In an especially preferred variant, the nonwoven material is vulcanized in light colors or white.
In contrast to coagulated products, a vulcanized nonwoven substrate remains open-pored,
because the open spaces in the nonwoven material do not become filled and clogged in a jelly-
like fashion.
Another advantage is that a vulcanized nonwoven substrate can be better filled with latex than,
for example, a self-linking nonwoven material. The latex is more strongly joined to the fibers
and fiber crossing points during vulc~ni7~tion, but the substrate nonetheless remains
outstandingly open-pored and has strong breathing activity.
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In this preferred vul~ni7~tion, the chain-type molecules made up of isoprenes are connected
to each other by sulphur bridges. Such vulcanized material has special elasticity and viscosity
and displays first-class reflexes, as clearly reflected by the perfect, first-class bouncing behavior
of sports balls. The particular benefit here is that players can maintain optimal soft contact
with the ball, without the ball bouncing away uncontrollably. The ball has first-class ball
guidance and, as needed, extremely fast acceleration.
Other important advantages are that a ball of vulcanized material maintains its original
resilience at various high and low temperatures, and that it does so even over years of storage,
without hardening of the synthetic upper material.
Another great advantage of a vulcanized nonwoven substrate is that the emulsifiers found in
every latex, which serve to keep the latex liquid during transport, are incorporated into the
nonwoven material during the vul~ni7~tion process. As a result, the ~mlllcifi~rs can no longer
become free during stretching and contraction of the nonwoven substrate, and thus cannot
cause moisture to build up in the open pores of the nonwoven material. Such emulsifiers act
like a soap and result, e.g., in self-linking nonwoven substrates, in insurmountable problems
in waterproofing. The open-poredness of the substrate and the usual stretching and
contraction of the upper material during use cause these emulsifiers, in conjunction with
moisture, to exercise a continuous suctioning effect. Any waterproofing thereby loses its
effectiveness.
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In testing, it was found that when two absolutely identical nonwoven substrates, one self-
linking and the other vulcanized, were washed and waterproofed in the same manner, the self-
linking material quickly became saturated with water. In contrast, the vulcanized substrate
displayed no buildup of moisture.
Given the aforementioned positive properties of vulcanized material, such a material can also
be used for shoe uppers, because long-lasting resistance to bending, tearing and contraction as
well as excellent suppleness, elasticity and--due to the open-poredness of the substrate--
breathing activity are ensured in this way.
The abrasion-resistant coating for a shoe upper material of this type can consist of either a
closed film or a porous, permeable film, primarily based on PU.
Furthermore, a vulcanized nonwoven substrate of this type can be used, without being coated
on the upper side, as a trimming material in shoes with a velour look, because such vulcanized
substrates have very high abrasion resistance.
Another possible use for such a substrate (also with a velour look) is in the area of indoor gym
balls with a damped bounce; as needed, the spun-fiber nonwoven material can be lined on the
back.
Alternatively, it is also possible for the various suggested nonwoven materials to be coagulated
with PU
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or foamed or coated with foam, e.g., high-solit [sic] PU foam or PVC foam, to achieve perfect
isotropic uniformity and elastic strength. It is also possible to coat a spun-fiber nonwoven
material with foam and to use this combination as a substrate or to provide it, in addition, an
.
abraslon-reslstant coatmg.
Another possibility is to use a nonwoven material that is formed with endless fibers, in the
manner of a spun-fiber nonwoven material, and then needle-bonded in a higher grammage and,
as needed, split. Furthermore, it is possible to use a spun-fiber nonwoven material that is
combined with woven fabric or knits, etc., and then coagulated with PU or vulcanized with
latex. Such a substrate can also be provided with an abrasion-resistant coating.
At the same time, the spun-fiber nonwoven material makes it possible to replace the
reinforcement l~min ~tion needed on the inside of the sports ball, which usually consists of
woven fabric, with spun-fiber nonwoven material, or to combine the spun-fiber nonwoven
material with woven fabric or knits.
The high processing and vulc~ni7~tion temperature of 140~ used to bond the nonwoven
material on the basis of latex results in first-class open-poredness in the nonwoven substrate.
At the same time, the working temperature of 140~ is most effective in combining sulphur and
latex during the bonding of the nonwoven material, and thereby ensures optimal, uniform
interconnection, resulting in first-class resilience and flexibility in the nonwoven substrate.
The latex simply covers and coats the fibers and fiber crossings in the nonwoven material,
wlthout
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filling in, sealing or clogging the substrate.
Another important advantage is that, thanks to the vul~ni7~tion, no negative after-hardening
of the substrate is caused by the sulphur. This would normally happen during further
processing steps such as condensation or heat coating between 140~ and 160~, for example.
Such a substrate would thereby after-harden and its properties would be negatively changed
by embrittlement.
Vulc~ni7~tion of the nonwoven material in white and light colors is especially preferred, as
is stabilization of the vulcanized spun-fiber nonwoven material with sulphur, and
waterproofing with fluorocarbon.
The invention is described in greater detail in the following description in reference to the
example shown in the drawing.
The drawing shows, in a partial cross-section, the structure of a composite material with three
layers, following the contours of a sports ball. Starting from an outer layer 1 of a highly
abrasion-resistant material, e.g., a material based on polyurethane, there is a second layer of
spun-fiber nonwoven material 2, which has uniform stretching and tearing strength
multi~im~n~ionally. This nonwoven material 2 absorbs the compressive stress produced by
the internal pressure of the rubber bladder 4. As a result, the ball maintains shape stability.
These material properties are found in a wide variety of nonwoven materials, such as
polyester, viscose polyester and polyamide, and in copolymers of other plastics, etc.
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Orders of magnitude of from 10 to 1000 N/5 cm can be assumed for the tearing strength.
Especially preferred are spun-fiber nonwoven materials that are bonded by vul~ni7~tion with
latex at high temperatures, as described above.
The spun-fiber nonwoven material is, as applicable, applied directly to an innermost layer 3,
which consists of soft and instable, i.e., non-bonded, staple-fiber nonwoven materials. The
object of layer 3 is to provide the desired bounce-damping and the necessary ball weight as
well as the properties needed to ensure a good ball feel and good ball guidance during play.
This innermost layer 3 can consist of a wide variety of short-fiber nonwoven materials, such
as microfiber nonwoven materials, coagulated nonwoven materials, poromeric nonwoven
materials, polyester nonwoven materials, polyamide nonwoven materials, felts, leather fiber
materials, glass fiber nonwoven materials, synthetic ceramic nonwoven material, and the like.
Thls )ommg of a stable spun-fiber nonwoven materlal that has umform stretchmg m multlple
directions to a non-rigid nonwoven material of short staple fibers results in optimal behavior.
Layers 2 and 3 can be joined to each other, for example, with the help of a polyurethane
adhesive or, if suitable materials are used, by bonding or a rubber adhesive and vul~ni7~tion.
It is especially preferable to bond the two materials by means of a hot-melt adhesive based on
thermoplastics .
Furthermore, it is preferable for the spun-fiber nonwoven material of layer 2 to serve as the
carrier on which the staple fibers,
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from which the nonwoven material layer 3 is formed in the known manner, are deposited
directly, to then be compressed into the nonwoven material.
To connect the spun-fiber nonwoven material and the short-fiber nonwoven material, it is
preferable to use an emulsion of natural or synthetic rubber that contains a silicone or
fluorocarbon waterproofing agent as well as, as applicable, urethane or acrylate as a binding
agent. When dried and vulcanized (in a self-linking manner, as applicable), this adhesive
creates a firm bond to the fiber contact points of the layers, but does not substantially reduce
porosity or gas permeability. Thanks to the contained waterproofing material, which is bound
into the rubber, the nonwoven material is provided in this same work step with protection
against penetration by liquid water. Surprisingly, a material pretreated in this way can still
adhere, despite the waterproofing, to the polyurethane layer 1 and, as applicable, to the
reinforcing woven fabrics or weight-giving woven fabrics or films under the nonwoven
material. The materials have good elasticity even in the cold.
In producing the composite material, it has proved advantageous to first connect the spun fiber
nonwoven layer and the inner nonwoven layer to each other, and to then apply the outer
plastic layer, either in the form of a hardenable dispersion of
aqueous polyurethanes
two-component polyurethanes
polyurethane on high-solid [sic] basis
or in the form of a thermoplastic powder or a prefabricated film, and then to
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implement bonding, either in a melting furnace or by means of infrared radiation. In this
way, the plastic partially penetrates the following layer, SQ that an especially secure connection
is attained. Corresponding techniques are known for producing other composite materials.
Less preferred, but also possible, is joining via a binding agent, for example, a latex or silicone
rubber adhesive.
It is especially preferable to equip the spun-fiber nonwoven material on its upper side with a
thin layer (0.2 - 1 mm) and on its bottom side with a thicker layer (1 - 5 mm) of staple fibers,
which are preferably joined to each other by needle-bonding, and then to impregnate this
composite layer with the aforementioned rubber waterproofing emulsion (20 - 40%), vulcanize
the composite in the furnace, abrade away its surface roughnesses and, only then, connect the
composite to the layer 1. The thin, largely re-abraded cover layer thus provides an especially
smooth backing for the plastic, but is still sufficiently honeycombed to permit adhesion of the
spun-fiber nonwoven layer.
The outer layer preferably has a leather-like grain on its surface, which is created during
production as usual with a suitably patterned stamping roller or applied via a release paper
coatlng.
Water can enter the interior through the seams of products made with the composite material
according to the invention and also, in part, through pores in the cover layer; the water then
is distributed in the nonwoven layers in capillary fashion. It has therefore proved
advantageous
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to prevent water penetration by waterproofing these materials. As a result, the material
becomes 100% watertight and does not gain weight even when wet.
Solutions or emulsions of known product groups, such as aluminum salts and ~irconium salts,
higher fatty acids, and fatty-acid modified m~l~mines, are suitable as waterproofing agents, as
are, preferably, solutions or emulsions of silicones, fluorosilicones and fluorocarbon resins.
It is also possible to combine the aforementioned components with polyurethane dispersions
or to carry out waterproofing completely on a dispersion basis. Surprisingly, materials
waterproofed in this way can still be coated by or cemented to polymers.
Either the waterproofing agent can be applied after production of the composite material, or
the nonwoven material can be impregnated with the waterproofing agent prior to l~min~tion
with the outer plastic cover. Prior impregnation has proved advantageous when the
waterproofing agent is applied with a solvent, in which the outer cover could be partially
dissolved. Subsequent impregnation is necessary if the waterproofing agent would impair the
adhesion between the outer plastic cover, the spun-fiber nonwoven material and/or the
nonwoven backing material. Suitable binding agents can be used in such cases. Because the
waterproofing agents do not fill the pores in the nonwoven material, but instead coat the
fibers thinly, the material remains aerated and can breathe actively.
Por this reason, the material is advantageously used as a shoe upper material. Because the
extremely slight isotropic stretching
13
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of the spun-fiber nonwoven material is a disadvantage in the case of shoe uppers and special
balls and thus, in given cases, greater stretching is preferred, the material must be specially
constructed in a two-layer fashion. The layer of spun-fiber nonwoven material can thereby
be omitted. This is also true for less expensive sports balls, in which greater stretching and
tolerances are acceptable. The special effect and highly effective property of a two-layer
material of this type are ensured by the latex binding of the substrate in conjunction with heat
vul~ni~tion and, as applicable, waterproofing.
The tensile strength and stretching found in a material with a 2-layer structure of this type
(staple-fiber nonwoven material and coating) are as follows (with reference to DIN 53328):
% of stretching at:
N/20 % of 50N lOON 150N 200N 250N
mm expan-
sion
Direction a 276 66 8.7 19.7 31.2 41.5 52.3
Direction b 368 103 13.7 33.1 47.4 59.7 70.7
Diagonally 332 95 11.8 27.9 41.8 53.8 65.0
Furthermore, the materials according to the invention are to be used in a wide temperature
range, e.g., between -10~ and +50~C. To prevent the plastics from becoming brittle at low
temperatures, it can therefore be advantageous to add known softeners (phthalate, adipate,
etc.). To inhibit the migration in the composite of such usually oily softeners, it is also
possible to interconnect the latter to the synthetic material or to condense them.
14
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Because different types of sports balls (soccer balls, handballs, volley balls, etc.) require
different siz:es, weights and bouncing behaviors, it may be necessar,v, in the case of a composite
material not especially matched to its purpose, to establish these properties by adding further
nonwoven layers or woven fabric layers between the cover and the rubber bladder.
