U.S. patent application number 12/702357 was filed with the patent office on 2010-07-08 for composite materials made from pretreated, adhesive coated beads.
Invention is credited to David W. Bainbridge.
Application Number | 20100173116 12/702357 |
Document ID | / |
Family ID | 46301662 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100173116 |
Kind Code |
A1 |
Bainbridge; David W. |
July 8, 2010 |
COMPOSITE MATERIALS MADE FROM PRETREATED, ADHESIVE COATED BEADS
Abstract
A composite material comprised of polymeric beads and adhesive,
primarily intended for use in constructing buildings, athletic
fields, waste pond covers, packaging, contact sports gear and
medial equipment, is comprised of a plurality of electrical
excitation zone-treated beads having average diameters between
about 1 mm and about 10 mm that are substantially coated with the
adhesive material and used in quantities such that void spaces
constitute at least about 10 percent by volume of the total volume
of the composite material. Upon curing, said adhesive preferably
has hardness levels ranging from about Shore A 20 to about Shore A
95.
Inventors: |
Bainbridge; David W.;
(Golden, CO) |
Correspondence
Address: |
MACMILLAN SOBANSKI & TODD, LLC
ONE MARITIME PLAZA FIFTH FLOOR, 720 WATER STREET
TOLEDO
OH
43604-1619
US
|
Family ID: |
46301662 |
Appl. No.: |
12/702357 |
Filed: |
February 9, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10685965 |
Oct 15, 2003 |
7662468 |
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12702357 |
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09684470 |
Oct 6, 2000 |
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10685965 |
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Current U.S.
Class: |
428/72 ;
428/338 |
Current CPC
Class: |
B29C 59/10 20130101;
B29C 44/3461 20130101; A41D 31/28 20190201; B29C 70/58 20130101;
Y10T 428/249991 20150401; Y10T 428/249971 20150401; Y10T 428/249985
20150401; Y10T 428/239 20150115; B29L 2031/732 20130101; Y10T
428/249982 20150401; Y10T 428/249983 20150401; B29C 59/14 20130101;
Y10T 428/268 20150115; Y10T 428/234 20150115; Y10T 428/249953
20150401; Y10T 428/249992 20150401 |
Class at
Publication: |
428/72 ;
428/338 |
International
Class: |
B32B 3/26 20060101
B32B003/26; B32B 5/16 20060101 B32B005/16; B32B 3/24 20060101
B32B003/24; B32B 3/00 20060101 B32B003/00 |
Claims
1. A composite material comprised of a plurality of beads having
average diameters that range from about 1 mm to about 10 mm and of
which at least 50 percent are at least 50 percent coated with an
adhesive, and wherein a cured form of the adhesive has a hardness
ranging from about Shore A 60 to about Shore A 95 and is used in a
quantity such that it represents between about 20 and about 80
weight percent of the composite material, thereby serving to create
a system of void spaces between the adhesive coated beads that
constitutes from about 10 to about 40 volume percent of the total
volume of the composite material.
2. The composite material of claim 1 wherein the adhesive coated
beads have average diameters that range from about 1 mm to about 4
mm.
3. The composite material of claim 1 wherein the beads are
inelastic.
4. The composite material of claim 1 wherein the beads are
elastic.
5. The composite material of claim 1 wherein the beads are made of
polymeric materials selected from the group consisting of
polyethylene, propylene, and ethyl propylene copolymer.
6. The composite material of claim 1 wherein the system of void
spaces is substantially comprised of substantially regularly
distributed void spaces.
7. The composite material of claim 1 wherein the beads have
diameters ranging from about 1 mm to about 4 mm.
8. The composite material of claim 1 wherein the beads are
solid.
9. The composite material of claim 1 wherein the beads are
hollow.
10. The composite material of claim 1 wherein the beads are made of
either a ceramic material, a glass material, or a plastic
material.
11. The composite material of claim 1 wherein the beads have one or
more holes passing through their bodies.
12. The composite material of claim 1 wherein the beads are made of
either a thermosetting material or a thermoplastic material.
13. The composite material of claim 1 wherein the adhesive is made
from a two part resin.
14. The composite material of claim 1 wherein the adhesive is made
from either a thermosetting synthetic resin or a thermoplastic
synthetic material.
15. The composite material of claim 1 wherein the beads are either
spherical or ellipsoid in shape.
16. The composite material of claim 1 wherein the beads are made of
different polymeric materials.
17. The composite material of claim 1 wherein the material is
placed in either a cloth-like casing or a net-like casing.
18. The composite material of claim 1 wherein the material is used
in conjunction with a hard plastic, outer shell.
19. The composite material of claim 1 wherein at least 50 percent
of the beads are at least 80 percent covered by the adhesive.
Description
RELATED APPLICATIONS
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 10/685,965 filed Oct. 15, 2003, now U.S. Pat.
No. 7,662,468 issued Feb. 16, 2010, which was a
continuation-in-part of U.S. patent application Ser. No. 09/684,470
filed Oct. 6, 2000, both of which are incorporated herein in their
entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention disclosed herein generally relates to the
field of composite materials. For the purposes of this patent
disclosure the term "composite material(s)" may be taken to mean a
mixture (on a macro scale) of two or more materials that are solid
in a finished state, are mutually insoluble, and differ in chemical
nature. Certain preferred composite materials for the practice of
the herein described invention are those polymeric beads associated
with each other through use of adhesive materials. Such polymeric
bead/adhesive composite materials are often referred to as "foam"
or "foamed" materials. The most preferred composite materials for
the practice are those polymeric bead/adhesive composite materials
wherein the polymeric bead component is comprised of beads that
have been treated in an electrically excited field.
[0004] The polymeric bead/adhesive composite materials of this
patent disclosure have a wide variety of uses. For example they can
be used as construction materials, insulation materials, sound
and/or vibration abatement materials, drainage control materials,
waste pond and/or landfill covers, packaging materials, padding for
sports gear and/or medical equipment that comes into contact with
the human body (e.g., helmets, shoulder pads, prosthetic devices,
mattresses, cushions, etc.), indeed virtually any application where
foam materials are employed. This invention also relates to
treating those polymer beads used to make composite materials so
that they will better form the end product materials of this patent
disclosure. Generally speaking these treatment processes involve
treating polymer beads in an electrically excited field.
[0005] 2. Discussion of the Background
[0006] Designing composite materials for a wide variety of purposes
(exterior wall and/or roof insulation, building foundation drainage
control systems, athletic field padding, e.g., to be placed under
athletic field turf, sound and/or vibration absorbing materials,
waste pond covers, protective padding sports equipment, prosthetic
devices, mattresses, etc. presents numerous challenges. For
example, composite materials used as insulation in wall or roof
construction is most preferably air breathable in nature. Composite
materials used in building foundation drainage systems must be
water permeable (preferably in all three directions). Designing
protective padding for impact absorbing athletic gear is especially
challenging. In addition to having the padding perform its primary
function of repeatedly absorbing high impact forces, such padding
also should be lightweight, air breathable, water permeable and
washable. It also should be easily integrated into sports gear such
as jerseys, pants, helmets, shoulder pads and the like--in a manner
that does not unduly inhibit the user's movements.
[0007] Thus, using athletic equipment design as an example of such
design challenges, one would note that many prior art pads and
padding techniques accomplish some of these goals--to varying
degrees. For example, U.S. Pat. No. 4,343,047 to Lazowski teaches
use of loosely filled, lightweight beads in a breathable casing to
form a helmet pad. The helmet pad readily conforms to the contours
of the wearer's head. In use, the loose beads are designed to move
or shift around relative to each other within the casing. The beads
also are designed to be crushable in order to absorb and attenuate
particularly high impact forces. Crushable beads of this kind are
designed to absorb one major impact, much like a car airbag.
Therefore, padding made from crushable beads cannot be used in most
athletic gear (e.g., football thigh and knee pads) since it must be
able to withstand repeated impacts without losing its mechanical
integrity.
[0008] Other prior art, sports-related, padding materials use
incompressible beads that are designed not to be crushed (e.g.,
British Patent No. 1,378,494 to Bolton, U.S. Pat. No. 3,459,179 to
Olesen, and U.S. Pat. No. 4,139,920 to Evans). Still others use
beads that are resilient rather than crushable (e.g., U.S. Pat. No.
3,552,044 to Wiele and U.S. Pat. No. 5,079,787 to Pollman). These
beads also are loosely packed in a bead containment sack or casing.
Here again, this allows the beads to move, roll, flow, etc.
relative to each other in order to achieve maximum pad conformation
to the shape of a particular part of the human body. The Wiele
patent further teaches lubrication of such beads to enhance their
flowability to achieve such conformation. In this art, these
loosely packed conditions are often referred to as "underfilling".
The general object of underfilling is to achieve a padding material
having the flow and conforming characteristics of a liquid-filled
pad, without the burden of carrying the relatively heavy weight of
liquids--or the need for waterproofing the casings needed to
contain them.
[0009] While underfilled pads initially behave like a liquid when
subjected to impacts, they have a tendency toward allowing the
beads contained therein to be permanently driven out of the way in
localized areas that receive repeated blows. This tendency
gradually reduces the thickness of the padding around the human
body part receiving the repeated blows. Indeed, this tendency may
even allow the human body part to eventually "bottom out" in the
pad. Under such bottomed out conditions, the beads are driven away
from the very areas where they are most needed.
[0010] Consequently, much of the padding used in today's athletic
equipment is comprised of one or more sheets or layers of foam-like
materials rather than underfilled pads. So used, these foam-like
materials have the distinct advantage of not easily bottoming out.
They also are relatively light in weight and inexpensive to
manufacture. There are two general types of foam padding materials.
The first type comprises so-called "closed cell" foams. Aside from
not being inclined to bottom out, such foams also have the
advantage of not absorbing moisture such as perspiration. However,
closed-cell foams tend to be stiff--and, hence, body
movement-stifling. Moreover, closed cell foam materials do not
readily conform to human body contours, particularly under the
rapidly changing conditions associated with many contact sports.
Moreover, closed-cell foams do not "breathe" very well and
therefore do not allow dissipation of the equipment user's body
heat. Closed cell foams also suffer from the fact that they are not
readily sewn into, or washable with, athletic clothing and
equipment such as jerseys, pants and the like.
[0011] The second type of foam commonly used in sports and medical
equipment comprises so-called "opened-cell" foams. These foams tend
to be softer and more pliable than closed-cell foams. Hence, they
tend to better conform to various contours of the human body,
especially under rapidly changing conditions. They also do not
inhibit the user's movements nearly as much as closed-cell foams.
Open-cell foams also have good breathing qualities. Opened-cell
foams do, however, tend to absorb and hold moisture and odor to
such a degree that this tendency is often regarded as their major
drawback. Hence, open-cell foams are usually coated with a
waterproofing material (e.g., vinyl and the like) to prevent high
levels of absorption of perspiration. Unfortunately, use of these
coating materials tends to make athletic pads made from opened-cell
foams considerably less breathable and, hence, more body
heat-retaining. Use of these coating materials also tends to make
the underlying pads less pliable.
[0012] Padding materials made from polystyrene, polyethylene and
polypropylene have proven to be especially efficacious in athletic
equipment (e.g., football helmets, shoulder pads, etc.) that must
repeatedly absorb impacts. The precursor beads (polystyrene,
polyethylene, polypropylene and mixtures thereof) from which these
materials are made are simply placed in a container and subjected
to heat treatments (e.g., steaming) in order to join the individual
beads to each other and thereby create unified materials from which
padding for sports equipment can be made. These manufacturing
processes are very generally depicted in FIGS. 2-7 of this patent
disclosure. For example, the cross-sectional bead array shown in
FIG. 2 can be heated (e.g., by steam) in order to join or meld the
individual beads 1, 2, 3, 4, 5, 6, etc. into a unified body of
material such as that depicted in FIG. 3. In FIG. 2, the individual
beads are shown having idealized, round configurations. This
implies that void spaces will exist between abutting individual
beads. Those skilled in this art will appreciate that these void
spaces become filled in when the beads are made fluid or plastic in
nature by the heat treatment used to join or meld the beads
together in the manner suggested in FIG. 3. After such heat
treatments, the composite body constitutes a "foam" from which
padding materials can be made. A perspective view of a generalized
block of such foam material is depicted in FIG. 4. It illustrates
that the void spaces shown in FIG. 2 become filled in (in all three
dimensions) by the material from which the individual beads are
made; hence the resulting foam material does not possess
particularly good breathing qualities.
[0013] Other composite materials, that are primarily used in
applications other than athletic equipment (e.g., building
materials such as those used in insulation slabs, sound/vibration
absorbing slabs, athletic turf padding/drainage control slabs,
building foundation drainage control slabs, waste pond covers,
etc.), have been designed to maintain void spaces between their
individual beads even after they have been subjected to such heat
treatments. The void spaces contribute to the relatively light
weight of such building materials. Such materials are usually made
from hollow microspheres or microbeads that are--to some
degree--covered with a resin material that is applied to the
microspheres by melting the resin material in the presence of the
beads. For example, U.S. Pat. No. 5,587,231 ("the '231 patent")
teaches a foam material made from a mixture of hollow ceramic
microspheres and dry granules of a resin powder. The dry resin
powder is a thermosetting or high-temperature thermoplastic whose
individual particles are mechanically mixed into a mass of dry
microspheres. Upon heating the hollow microsphere/resin mixture to
the resin powder's melting point, the microspheres become bonded
together by a cured form of the resin that results from the heat
treatment and subsequent cooling of the melted resin material. That
is to say that the resin is in a melted state when it first goes
into a liquid state (by virtue of having been melted) and makes its
initial contact with the beads in this liquid (and melted) state.
The end product material is an array of (1) hollow ceramic
microspheres, (2) a thermally set resin that interconnects
individual microspheres and thereby serves to hold said
microspheres in a cohesive body and (3) void spaces. Optionally,
the material may contain fiber strands as well. These materials are
depicted in FIGS. 2A and 2B of the '231 patent as well as in FIG.
12 of the present patent disclosure.
[0014] Because the dry resin powder taught in the '231 patent
disclosure is simply mechanically mixed with the microspheres, the
resulting materials are, to some degree, characterized by the fact
that the cured resin does not tend to fully coat the microspheres
(again see FIGS. 2A and 2B of the '231 patent or FIG. 12 of the
present patent disclosure). That is to say that the '231 patent's
thermally set resin material associates with the beads in such a
manner that it generally serves to form branch-like, or net-like,
components whose individual elements serve to interconnect the
beads at certain limited locations on the bead's surface--as
opposed to fully coating the microspheres. The '231 patent's end
product materials also are characterized by the fact that the void
spaces created by the thermal setting of the resin tend to be
"clogged" and somewhat randomly created in said materials. Hence,
the breathing qualities of these materials are not particularly
good. This is, however, of little or no concern to the '231 patent
disclosure because its light weight materials are intended for use
as construction materials in buildings, aircraft, trucks, boats,
tanks and the like. These breathing qualities will be contrasted
with the padding materials of applicant's patent disclosure wherein
the resulting bead/adhesive/void space materials remain highly
breathable and hence better suited for use in athletic equipment or
medical equipment.
[0015] U.S. Pat. No. 5,888,642 ("the '642 patent") teaches a
padding material similar to that taught in the '231 patent. It is
comprised of microspheres that are held together in a coherent body
by two resins. One of these resins is melted and subsequently
thermally set. The teachings of this patent disclosure differ from
those of the '231 patent in that the second resin in the '642
patent forms microballoons when suitably heated. In any case, the
resulting material also has an array of hollow beads, resins and
void spaces. It does not, however, necessarily have fiber strands
as part of its make as in the case in the '231 patent. A
representative material is shown in FIG. 9 of the '642 patent and
in FIG. 11a of the present patent disclosure. As was the case in
the '231 patent, the materials taught by the '642 patent are
intended for use as construction materials rather than as padding
for athletic equipment or medical equipment.
[0016] U.S. Pat. No. 3,640,787 to Heller teaches a method of making
construction materials from fully coating shaped beads of low
specific gravity (e.g., polystyrene) with a liquid binder material.
In effect, the beads are first immersed in a liquid form of the
binder. This immersion fully coats the beads. The resulting
binder-covered beads are, in turn, coated with a solid pulverulent
material such as particles of metal oxides, sand and the like. FIG.
4 of the Heller patent disclosure shows that cell-like bodies are
formed from the beads (e.g., polystyrene beads) and that the walls
of these cells are comprised of the hardened binder material which
also contains the pulverulent materials embedded therein. Since the
resulting honeycomb-like materials have no void spaces between its
adjoining cells, the resulting material does not have good
breathing qualities. In other words, Heller's individual cells do
have void spaces, but they are totally surrounded by the cell walls
created from the beads and binder/pulverant coating on those cell
walls. Here again, however, this is of little concern to the Heller
patent disclosure since its end product materials also appear to be
intended for use as building construction materials rather than
padding for athletic equipment.
[0017] Thus, there remains a continuing need for composite
materials that are particularly characterized by the fact that they
are highly breathable, water permeable (especially in all three
directions) light in weight, conformable to the human body, and
able to withstand repeated blows without mechanically breaking down
and/or bottoming out. To this end, the composite materials
disclosed herein have high levels of all of these desired
qualities. Moreover, they can be easily incorporated into a wide
variety of applications. They also are (if need be) washable and
relatively easy, and inexpensive, to make.
[0018] It might also be noted that, even though their ability to
repeatedly absorb blows may not be needed, the other attributes of
these padding materials (breathability, light weight,
conformability to the human body) also make them well suited for
use in medically related devices such as prosthetic devices,
cushions, mattresses and the like. Moreover, the breathing
qualities of these materials may, alone, make them suitable for use
as padding for certain goods that must be exposed to air during
shipping. The breathability of these composite materials also makes
them useful as filters. For example they would be particularly
useful in equipment where both padding and filtering functions must
be performed by the same material. By way of example only,
applicant's materials can be used as padding in electrical
equipment such as computer hard drive equipment that must be
protected from mechanical disturbances and subjected to a stream of
cooling air that must be filtered before introduced into hard
drives that have very little tolerance for particles of foreign
materials. There are of course many applications where
"breathability" may not be a particularly important attribute--but
does no harm in that application (building insulation,
soundproofing, drainage control packaging, etc.).
SUMMARY OF THE INVENTION
[0019] This invention relates to processes and apparatus for making
composite materials. Such composite materials are primarily
comprised of polymer beads and adhesive materials. Additives such
as flame retardant agents and the like may also be present. In any
case, applicant's processes begin with corona, plasma, hybrid
corona/plasma and/or glow discharge treatments of the polymer beads
that will be combined with an adhesive material to make the subject
composite materials. Thus, for the purposes of this patent
disclosure these beads can be referred to as "electrical excitation
zone-treated" particles, beads, etc. The polymer beads treated by
the apparatus and processes of this patent disclosure will
generally range in average diameter from about 1 millimeter (mm) to
about 10 mm. Treatment of those beads ranging in average diameter
from about 1 to about 4 mm is even more preferred. The treatments
of this patent disclosure may be directed at an entire bead body
(e.g., causation of a chemical reaction of substantially all of the
material from which a given bead is made). However, in some of the
most preferred embodiments of this invention, the herein described
electrical excitation zone treatment processes will primarily be
used to effect treatments of the surface areas of the subject
polymer beads.
[0020] Such surface treatments can, for example, be used to cause
chemical reactions of the surface molecules of a given polymer bead
in order to create certain desired chemical groups. That is to say
that, in effect, the electrical excitation zone treatments of this
patent disclosure can cause electrons and/or ions having different
energies to hit a given polymer bead's surface and thereby causing
molecular chains comprising the bead's surface to be broken in a
manner such that new functional chemical groups are formed. By way
of example only, such chemical groups can be those having oxygen
based radicals, e.g., carboxyl groups, hydroxyl groups, peroxide
groups and the like. The creation of such functional groups is
especially efficacious in bonding the treated beads with various
adhesives used to bind an array of such beads together in order to
produce larger formed materials such as foams. Other embodiments of
this invention may be used to remove contaminating materials (e.g.,
water, oil, foreign chemical films, foreign particles and the like)
from the surface regions of such beads. Such decontamination
treatments are particularly effective when the contaminating
substance is volatile in nature (e.g., water, oil and/or chemicals
in liquid forms). These surface treatments also may be used to etch
or otherwise physically change the topographies of certain polymer
beads. Generally speaking, new surface topographies are created on
treated beads when ions generated in the electrical fields created
by the apparatus of this patent disclosure hit the surfaces of said
beads with a distribution of different energies.
[0021] Regardless of the molecular structure of the polymers from
which the subject particles are made, or the purpose of their
treatments (e.g., causation of chemical reactions, particle surface
cleaning, etching, deposition of particle surface coatings and the
like), the basic treatments of this patent disclosure will include
the steps of: (1) introducing polymeric beads into an electrical
excitation chamber (e.g., a corona, plasma, hybrid corona/plasma
and/or glow discharge etc. chamber), (2) introducing at least one
gas into the electrical excitation chamber to create a bead/gas
mixture, (3) directing the bead/gas mixture through at least one
electrical excitation zone created in the excitation chamber, (4)
creating an electrically excited gas that treats the beads and (5)
removing a resulting treated bead/gas mixture from said chamber.
Some preferred embodiments of this invention may involve treating
beads with a first electrically excited gas to achieve a first
purpose (e.g., cleaning), removing that gas from the excitation
chamber and treating the beads with a second electrically excited
gas to achieve a second purpose (e.g., deposition).
[0022] Next, it should be noted that in those cases involving
creating chemical functional groups, the cleaning particle surface
and/or etching gas may be an inert gas such as nitrogen and/or
argon. In the case of deposition coating such beads, however, the
gas will not be inert, but rather be a gas that is (1) capable of
being ionized under the electrical field conditions employed by the
herein described processes and (2) capable of being deposited on
the surface of the subject beads. The use of one or more of gases
having these characteristics with one or more inert gases is also
possible in the practice of this invention. It should also be noted
that an electrical excitation chamber used to carry out the
processes of this patent disclosure may be, but need not be, under
vacuum conditions according to certain considerations hereinafter
more fully described.
[0023] Some particularly preferred embodiments of this invention
will further comprise the use of more than one electrical
excitation electrode to produce more than one electrical excitation
zone in the electrical excitation chamber. Still other particularly
preferred embodiments of this invention will employ multiple
electrical excitation zones whose fields overlap. These multiple
electrical excitation zones will preferably be created through use
of at least one electrical excitation electrode located within the
electrical excitation chamber and at least one electrically opposed
electrode (e.g., a ground electrode) that is separated from the
excitation electrode by a dielectric material at a distance that
permits flow of a bead/gas mixture between said excitation
electrode and said dielectric material. The electrically opposed
electrode can be positioned inside of the electrical excitation
chamber (e.g., in the manner generally depicted in FIG. 4 of U.S.
Pat. No. 5,357,015). However, in some of the most preferred
embodiments of this invention, the opposing electrode (preferably a
grounding electrode, rather than an excitation electrode) will be
located outside of the body of the electrical excitation chamber.
Other particularly preferred embodiments of this invention will
employ bead flow directing devices and/or gas stream directing
devices to direct a bead/gas mixture through the electrical
excitation zone(s). Other particularly preferred embodiments of
this invention will employ hybrid corona/plasma field creating
apparatus hereinafter more fully described to created electrical
excitation zones. Their hybrid corona/plasma treatments are
especially useful in effecting surface treatments of certain
polymeric beads. Still other preferred embodiments of this
invention will employ treatment apparatus that have a series of
interconnected treatment vessels (e.g., three such interconnected
vessels) that are particularly well suited to carrying out
"continuous" or semi-continuous operations (as opposed to "batch"
operations). Still other embodiments will employ excitation
chambers as connecting devices between vessels (e.g., in an
apparatus comprised of a series of vessels that carry out
continuous or semi-continuous embodiments of the herein described
particle treatment particles).
[0024] Be these processes and/or apparatus features as they may,
applicant's composite materials are comprised of three dimensional
arrays of beads that are treated by the above described processes
before they are bound together in a coherent body (e.g., a slab) by
an adhesive that substantially covers or coats a major portion
(i.e., at least 50%, preferably at least 80% and most preferably,
substantially 100%) of all of the beads in said coherent body. In
order to best do this, the adhesive will constitute from about 20
to about 150 weight percent of the composite material. Moreover,
upon curing, the adhesive should have a hardness level ranging from
about Shore A 20 to about Shore A 95. The resulting composite
materials also should have void volumes that constitute from about
10 to about 40 volume percent of that material. The adhesive coated
beads used to make these composite materials will generally have
overall diameters (i.e., bead diameter plus coating thickness)
ranging from about 1 to about 10 millimeters ("mm"). In some of the
more preferred embodiments of this invention, however, these coated
beads will have average diameters ranging from about 1 to about 4
mm.
[0025] More specifically, applicant has found that the
breathability, water porosity, impact resistance, washability and
ease of manufacture of the composite materials of this patent
disclosure are achieved when the beads from which the composite
materials are made are pretreated in a manner hereinafter more
fully described--before they are coated with adhesives. These bead
pretreatments will include the steps of: (1) introducing the
subject beads into an electrical excitation chamber (e.g., a
corona, plasma, hybrid corona/plasma and/or glow discharge etc.
chamber), (2) introducing at least one gas into the electrical
excitation chamber to create a bead/gas mixture, (3) directing the
bead/gas mixture through at least one electrical excitation zone
created in the excitation chamber, (4) creating an electrically
excited gas that treats the beads and (5) removing the resulting
treated bead/gas mixture from said chamber.
[0026] Applicant's substantial adhesive coating of these electrical
excitation zone-treated beads can be improved upon by virtue of the
fact that the adhesive is associated with the beads while said
adhesive is in a liquid (or semi-liquid) state. More preferably,
this liquid state is not brought about by melting said adhesive
material(s). In other words, applicant's adhesive is most
preferably not in a melted state when it is, as a liquid or
semi-liquid, initially placed in contact with the beads. The
adhesive is then cured or hardened from its initial liquid state
(wherein the adhesive is not in a melted state) while in contact
with said beads. Thus, for the purposes of this patent disclosure,
expressions such as "adhesive cured from a liquid state (or
semi-liquid state) wherein the adhesive is not melted while in
contact with individual beads" means that applicant's adhesive
compositions are not made to be liquids (or semi-liquids) by
melting their adhesive components. This circumstance is to be
contrasted with the teachings of the '231 and '642 patents wherein
beads are associated with dry resin particles which are first
melted (and thereby become liquids or semi-liquids) and thereafter
allowed to set in order to create the thereindisclosed
bead/resin/void space systems.
[0027] Next, applicant notes that, for the purposes of the present
patent disclosure, the expression "substantially coats" should be
taken to mean that an adhesive material covers at least 50 percent
of a pretreated bead's surface area. Preferably, the majority of
the pretreated beads in applicant's resulting padding materials
will be at least 60% covered by an adhesive layer. More preferably,
at least 80% of the pretreated beads in a given body of the
composite materials of this patent disclosure will be at least 80%
covered by such an adhesive material. Most preferably,
substantially 100% of such beads will be substantially 100% covered
with the liquid adhesive. To these ends, the liquid adhesive
compositions of this patent disclosure will have viscosities
ranging from about 500 centipoises ("cps") to about 5000 cps under
ambient conditions. Generally speaking, the liquid adhesive
composition will be capable of wetting the pretreated beads upon
contact.
[0028] As was previously noted, the cured form of the adhesives
employed in applicant's padding materials will have Shore hardness
levels ranging from about Shore A 20 to about Shore A 95. In some
of the most preferred embodiments of this invention, the Shore
hardness levels of the cured adhesive coatings will range from
about Shore A 60 to about Shore A 90. It also should be noted that,
even after their volatile components have left the adhesive
material as part of the curing process, the adhesive component of
the end product material will represent a major part (20-80%) of
the weight of the padding material even though it may represent a
relatively minor part of the material's volume. Indeed, for reasons
hereinafter more fully discussed, these adhesive materials will
usually represent no more than about 5 volume percent of
applicant's finished product composite materials.
[0029] The composite materials made according to the teachings of
this patent disclosure also are particularly characterized by their
possession of relatively large void volumes that are comprised of a
large number of smaller void volumes that are, to a substantial
degree, regularly spaced from each other. Moreover, these smaller
void volumes are, to a large degree, in fluid communication with
each other. This is to be contrasted with the totally encapsulated
void volumes, if any, of the cells of the '787 patent disclosure
(see FIG. 4 thereof). The presence of an array of regularly spaced
and greatly interconnected void volumes gives applicant's composite
materials a particularly porous (e.g., water permeable), breathable
(e.g., air breathable) quality that greatly enhances their
viability as athletic or medical equipment components. That is to
say that the particularly good porosity and breathing qualities
resulting from this array of regularly spaced void spaces that are
in fluid communication with each other, produces improved
perspiration evaporation and, hence, improved body heat
dissipation, qualities in applicant's composite materials that are
used in association with the human body, e.g., padding materials in
athletic equipment, prosthetic devices, mattresses and the
like.
[0030] For purposes of this patent disclosure the expression
"regularly spaced" should be taken to mean that (on average), at
least one void space will preferably be present between at least
every third bead (in all three dimensions). In some of the more
preferred embodiments of this invention, this regularity will imply
that such void spaces ideally will be present (on average) between
every second bead. In some of the most preferred forms of
applicant's composite materials, a void space will (on average)
exist between substantially every bead in a body of said materials.
The breathing qualities of applicant's composite materials
generally tend to improve as this ideal is approached. Preferably,
these void spaces will constitute at least about 10 percent, but no
more than about 40 percent, of the total volume of the resulting
composite material.
[0031] Applicant has found that the presence of these regularly
spaced void spaces are preferably brought about when the adhesive
is applied in a liquid (or semi-liquid) state to the surface of the
beads in quantities such that a subsequent dry form of the adhesive
(resulting from its curing and/or drying) constitutes from about 20
weight percent to about 80 weight percent of applicant's end
product, bead/adhesive/void space-comprised composite materials. In
some of the most preferred embodiments of this invention the dried
or cured form of the relatively hard adhesive will represent from
about 40 to about 60 weight percent of applicant's end product
composite materials.
[0032] In the case of use of applicant's composite materials being
used as padding materials used in sporting or medical equipment,
said materials will be placed in a pliable casing material such as
a cloth-like, or web-like bag, casing or cover. When used in
contact sports equipment, these padding materials (and their
coverings) can be further associated with shell-like, outer facing,
inelastic materials such as those hard plastic materials from which
the outer surfaces of football helmets, football shoulder pads,
thigh pads and the like are made. Some representative uses of
applicant's padding materials in such equipment will be more fully
illustrated in subsequent portions of this patent disclosure.
Again, the porous, breathable, padding materials of this patent
disclosure make them particularly well suited for use in athletic
or medical equipment. They can, however, also be used when
lightweight, shock absorption, or breathability are not strongly
called for; e.g., in other applications such as construction
materials such as those slabs of composite materials placed (1)
around building foundations, (2) under artificial athletic playing
fields, (3) under floors, (4) between walls and so forth. These
padding materials also can be used as shipment padding and
packaging materials for shipping other objects (such as mechanical
or electrical equipment, fruit, eggs or vegetables), air filters,
waste pond covers, light weight sound and/or vibration abatement
materials and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 depicts a preferred embodiment of this invention
wherein an electrical excitation chamber is provided with three
separate and distinct excitation electrodes within the chamber and
one opposing electrode (i.e., grounding electrode) positioned
outside of the excitation chamber.
[0034] FIG. 2 depicts (in cross section) a general array of prior
art, foamable beads that are generally separated by void spaces
20.
[0035] FIG. 3 depicts the result of heating the prior art foamable
beads of FIG. 2 (e.g., by steaming). In effect, the individual
beads become, to some degree, melded or joined together by the heat
treatment. That is to say that the beads 1, 2, 3, 4, 5, etc. shown
in
[0036] FIG. 3 are no longer the distinctly round particles shown in
FIG. 2, but rather are partially melded or joined to one another in
a manner that substantially fills in the void spaces 20 depicted in
FIG. 2.
[0037] FIG. 4 depicts a three dimensional block of the material
shown in FIG. 3. Such a three dimensional block of material can be
created by molding operations known to this art, or can be cut from
slabs to desired shapes for use as padding materials including
padding for athletic equipment.
[0038] FIG. 5 depicts a prior art bead system similar to the one
depicted in FIG. 2. FIG. 5 however shows some of the beads (i.e.,
beads 2, 3, 4, 5, 6 and 7) as being made of a material different
from the remainder of the beads.
[0039] FIG. 6 depicts the result of melding the beads shown in FIG.
5 into a mixed bead system.
[0040] FIG. 7 depicts a three dimensional block of the material
shown in FIG. 6. It should be specifically noted that the resulting
materials shown in FIGS. 4 and 7 do not generally have distinct
void spaces after the beads have been melded together by a heat
treatment.
[0041] FIG. 8 depicts a prior art system comprised of beads 1-19
that are held together in a coherent unit by a polymeric material
22. This polymeric material 22, in effect, fills in all of the void
spaces between the various beads.
[0042] FIG. 9 depicts a prior art system wherein a polymeric
material 22 used to associate the beads 1-19 is employed in
proportions such that the beads may be considered to be "immersed"
in said polymeric material 22.
[0043] FIG. 10 depicts a prior art system similar to that shown in
FIG. 8. It does however differ from the system shown in FIG. 8 in
that some of the beads are made from materials different from the
remainder of the beads. For example, in FIG. 10 beads 2, 3, 4, 5, 6
and 7 are depicted as being made from a material different from
beads 1, and 8-19.
[0044] FIG. 11 shows a prior art system similar to that shown in
FIG. 9 except for the fact that some of the polymeric
material-immersed beads (i.e., beads 2, 3, 4, 5, 6, 7) are made of
a material different from the material from which the remainder of
the beads are made. All of the beads can be considered as being
totally immersed in the polymeric material 22.
[0045] FIG. 12 shows a prior art padding material (as taught by
FIGS. 2A and 2B of the '231 patent) made from hollow ceramic
microspheres that are held together in a coherent body by a resin
material that interconnects the individual beads. The resulting
material also has distinct void spaces 20 and fibers distributed
throughout its structure.
[0046] FIG. 12A shows a prior art padding material (as taught by
FIG. 10 of the '642 patent) made from hollow microspheres and two
distinct kinds of resin--one of which forms microballoons when
heated. This material has distinct void spaces 20.
[0047] FIG. 13 depicts a basic component of the composite materials
of the present patent disclosure. It shows a single solid bead 24
covered by a layer of adhesive material 26. The bead 24 can be made
from an inelastic material or an elastic material.
[0048] FIG. 14 depicts a two component bead that also can be used
to make the hereindisclosed composite materials. The bead has an
inner, solid, bead 24 having a cover layer 24(a) of bead material
that is different from the material from which the inner bead 24 is
made. Thus, the resulting bead has two components 24 and 24(a) that
each can be made of elastic or inelastic materials. This two
component bead is shown about 50% covered with an adhesive layer 26
of varying thickness 27 (27').
[0049] FIG. 15 depicts a solid bead having an ellipsoidal
configuration that also can be used in the practice of this
invention. Said ellipsoidal bead is shown about 80% covered with a
layer of adhesive 26 of varying thickness 27''.
[0050] FIG. 16 shows a portion of an idealized, two dimensional,
bead system wherein the beads are solid and wherein every third
bead in this two dimensional presentation is regularly provided
with an adjacent void space 20.
[0051] FIG. 17 shows a portion of an idealized bead system wherein
every second bead is regularly provided with an adjacent void space
20.
[0052] FIG. 18 shows a portion of an idealized bead system wherein
every bead is regularly provided with an adjacent void space
20.
[0053] FIG. 19 depicts another two dimensional system of
adhesive-coated beads associated in a manner taught by this patent
disclosure. Said system is comprised of essentially round, solid
beads (such as that shown in FIG. 13) that are completely coated
with a layer of adhesive material of substantially uniform
thickness.
[0054] FIG. 19A depicts an array of beads wherein some of the beads
are not totally covered by the adhesive and wherein some of the
bead bodies have, to some degree, melted together.
[0055] FIG. 20 depicts an bead/adhesive/void composite material
system of this patent disclosure that is comprised of uniformly
coated beads made from three different bead construction materials
and wherein some of the beads have holes passing through the body
of the bead.
[0056] FIG. 21 depicts an bead/adhesive/void space composite
material of this patent disclosure that features the use of beads
of different sizes and different construction materials as well as
the use of non-coated beads in such composite materials.
[0057] FIG. 22 illustrates the composite materials of the present
invention integrated into various items of football equipment.
[0058] FIG. 23 is a cross-sectional view of a pad made according to
the teachings of this patent disclosure. Such pads can be used in
various items of equipment for contact sports such as football,
hockey, lacrosse and the like.
[0059] FIG. 24 is an exploded view of a football thigh pad that
employs the padding materials of this patent disclosure in
conjunction with an outer facing shell made of a hard plastic
material.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0060] FIG. 1 depicts, in cross-section, a preferred apparatus 10
for carrying out a preferred process for treating polymer beads
according to the teachings of this patent disclosure. The apparatus
10 has an electrical excitation chamber 12 that, in this preferred
embodiment, is shown housing three separate and distinct excitation
electrodes 14, 16 and 18. A single opposing electrode 20 is shown
positioned outside of the electrical excitation chamber wall 12A.
The electrical excitation chamber 12 (or at least that portion of
the chamber which separates electrodes 14, 16 and 18 from the
opposing electrode 20) is made of a dielectric material such as
glass, a ceramic material or a polymeric material having suitable
dielectric properties. Thus, in this preferred embodiment, the
electrical excitation chamber wall 12A shown in FIG. 1 both
physically and electrically separates electrodes 14, 16 and 18 from
the electrically opposed electrode 20.
[0061] This physical arrangement of these electrically opposed
electrodes serves to create an electrical field or electrical
excitation zone between each of the respective electrodes 14, 16
and 18 and the opposing electrode 20. Such electrical field
creations can be created in excitation chambers under positive gas
pressures. However, in some particularly preferred embodiments of
this invention, the creation of the required electrical fields can
be enhanced through use of vacuum conditions (e.g., those ranging
from about 5 to about 460 torr) in the excitation chamber 12.
[0062] The right end of the top electrode 14 of FIG. 1 is shown
creating a generalized electrical excitation zone bound by lines
connecting points 14A, 14B, 14C and 14A. Similarly, the right end
of the center electrode 16 is shown creating an electrical
excitation zone bounded by lines connecting points 16A, 16B, 16C
and 16A. Likewise, the bottom electrode 18 is depicted creating an
electrical excitation zone bound by lines connecting points 18A,
18B, 18C and 18A.
[0063] To illustrate another particularly preferred embodiment of
this invention, these three electrical excitation zones are shown
in FIG. 1 having overlapping regions. For example, the electrical
excitation zone created by the top electrode 14 is shown
overlapping the electrical excitation zone created by the center
electrode 16 in the region generally bounded by lines connecting
points 14D, 16B, 14C and 14D. Similarly, the excitation zone
created by the bottom electrode 18 is shown overlapping the
electrical excitation zone created by the center electrode 16 in
the region generally bounded by lines connecting points 16D, 18B,
16C and 16D. Thus, use of these multiple excitation zones serves to
increase the dwell time of a given bead in an excitation zone as
well as subject it to differing excitation zone electrical
intensities (and especially when the electrical excitation zones
have overlapping regions). Each of the above factors can be
employed to increase the bead throughput capacities of the bead
treatment apparatus of this patent disclosure.
[0064] FIG. 1 also shows an opposing electrode 20 (e.g., an
electrode that carries out an electrical grounding function) in a
preferred physical form in a preferred mode of use, i.e., a belt or
ring that snugly encompasses the outside surface of the electrical
excitation chamber 12. The most preferred location for such a
single, belt-configured, grounding electrode is generally opposite
the center region of the 3 electrode array (i.e., generally
laterally opposite the end of the center electrode 16 as shown in
FIG. 1). In this preferred embodiment, the grounding electrode 20
is shown surrounding the outside surface of a tubular shaped
excitation chamber 12. The use of opposing electrodes having other
geometries (e.g., electrodes having block configurations) is also
possible, but not preferred. The use of more than one opposing
electrode is also possible--but, likewise, not preferred.
[0065] The electrical excitation electrodes are preferably
connected to a common electrical power source 28 via electrical
line 30. In the alternative, each excitation electrode may be
connected to its own separate and distinct power source. In either
case, however, some of the more preferred embodiments of this
invention will employ from 1 to about 10 excitation electrodes (but
most preferably from 3 to 4 excitation electrodes) powered by an
electrical source that is preferably rated at between about 50
Watts and about 1000 Watts, at about 100 kV and 500 kV and having
frequencies ranging from about 2 MHz to about 5 MHz. It also should
be noted that these ratings are much greater than those (e.g., 4
Watts, 10 kV and 1 kHz) used to surface treat polymer films. For
example, applicant has found that electrical excitation zones
created by bead treatment devices having three electrodes connected
to a common power supply 28 rated at about 756 Watts, about 250 kV
and about 4 MHz are particularly well suited for surface treating
polymer beads (e.g., those made of polypropylene, polyethylene,
polystyrene, polyester and the like) having average diameters of
from about 1 to about 4 mm without damaging said beads. Moreover,
applicant's use of the above-noted, significantly higher,
electrical power ratings, voltages and frequencies with respect to
particles does not produce the previously noted problems (e.g.,
non-uniform treatments, heat damage to polymer materials, etc.)
encountered in many prior art plasma or corona treatments of
film-like polymer materials. Indeed, applicant has found that
backside treatment of polymer beads is caused by the above noted
higher power ratings, voltages and frequencies and that such
backside treatment is a generally desirable attribute--as opposed
to the prior art situation where backside treatment of film-like
polymers is regarded as a serious detriment.
[0066] The geometries, sizes and separation distances of the
excitation electrodes also can play significant roles in the
overall practice of this invention. For example, FIG. 1 depicts
electrodes 14, 16 and 18 as having saucer-like configurations which
are particularly preferred for the practice of this invention.
Differences in the diameters of the excitation electrodes 14, 16
and 18 (i.e., D.sub.1, D.sub.2 and D.sub.3 respectively) of this
patent disclosure also can play a significant role in the operation
of the particle treatment apparatus of this patent disclosure.
Applicant has, for example, found that those particle treatment
apparatus having multiple excitation electrodes of differing sizes
(and, hence, differing distances to the same grounding electrode
20) serve to provide higher operating efficiencies (i.e., higher
bead weight throughputs per unit time of the apparatus of this
patent disclosure). One particularly preferred embodiment of this
invention (e.g., employing the above-noted 756 Watt, 250 kV, 4 MHz
power supply) utilizes a saucer-shaped top electrode 14 having a
diameter D.sub.1 of about 8 inches, a saucer-shaped middle
electrode 16 having a diameter D.sub.2 of about 7 inches and a
bottom, saucer-shaped electrode 18 having a diameter D.sub.3 of
about 6 inches. In the case of the use of a common power supply 28
(e.g., the previously noted 756 Watt power supply), these different
electrode diameters can be used to create excitation zones of
different electrical intensities (e.g., a distribution of different
energies). Moreover, these electrodes 14, 16 and 18 are most
preferably arranged in a descending order of size (e.g., 8, 7, 6
inches respectively) depicted in FIG. 1. Applicant has also found
that, using the 756 Watt power supply noted above, employment of a
belt-like ground electrode 20 having a width of about 1-4 inches is
preferred. Under these same parameters, use of a tubular excitation
chamber 12 having an internal diameter of about 10 inches gives
especially good results in the case of treating polymeric beads
having average diameters of from about 1 mm to about 4 mm.
[0067] The vertical distances between electrodes 14, 16 and 18 (and
especially in the case of use of a common power supply 28) may also
be adjusted to suit particular applications of these treatments to
specific bead materials, sizes, throughput velocities, etc.
Preferably, the vertical distances between the excitation
electrodes 14, 16 and 18 will range from about 0.25 to about 1.5
inches--with vertical electrode separation distances of about 1
inch being preferred when used in conjunction with the above noted
756 Watt power supply. Use of differing vertical separation
distances between the various excitation electrodes also may be
employed depending on the power supply characteristics and the
chemical nature of the beads being treated. To a certain extent,
these vertical distances between said electrodes also will depend
on the geometry and/or diameter of the excitation electrodes, the
width of the grounding electrode 20 and/or its distance from the
ends of the excitation electrodes.
[0068] FIG. 1 also depicts a generalized stream of polymeric beads
22 (see representative bead 26p) entering a top 24 portion of the
electrical excitation chamber 12. This generalized stream of beads
22 (e.g., beads entrained in an air stream, inert gas stream,
non-inert gas stream and the like) is shown being directed downward
in one or more substreams 26, 26A, etc. When the electrical
excitation electrodes have the saucer-like configurations depicted
in FIG. 1, the bead substreams 26A, 26B, etc. generally flow around
and downwardly past the circumferential edges of such saucer-like
electrodes.
[0069] These substreams 26A, 26B, etc. are preferably directed in
flow patterns that serve to force the beads they entrain through
the electrical excitation zones created by the three excitation
electrodes 14, 16 and 18. In some of the more preferred embodiments
of this patent disclosure, the width of the most narrow electrical
excitation zone (i.e., the distance between the end of the largest,
saucer-shaped top electrode 14, and the wall 12A of the excitation
chamber 12) will be from about 0.25 inches to about 8.0 inches
(e.g., about 2.0 inches in the case of the use of the previously
described 756 Watt power supply).
[0070] In another particularly preferred embodiment of this
invention, the incoming stream of beads 22 will pass through one or
more particle flow directing devices 32, 32A (so-called wobblers,
suction creating devices, centrifuge devices, etc.) after said
beads 22 enter the excitation chamber 12. For example, such a flow
directing device 32 can subject the incoming beads to a flow action
that directs the beads downwardly past the circular edge of the
saucer-shaped top electrode 14 and through the underlying
electrical excitation zone(s). In another particularly preferred
embodiment of this invention, however, a suction type bead flow
directing device 32A is placed in the lower regions of the chamber
12 so that it serves to pull streams of incoming beads 26A, 26B,
etc. downward and through the electrical excitation zones. After
passing through the last electrical excitation zone, the treated
bead/gas mixture continues to flow in a downward path 38 and exits
the electrical excitation chamber 12 via exit opening 40.
Thereafter the resulting treated bead/gas mixture can be separated
(e.g., by a separator 42) into a bead component 44 and a gas
component 46.
[0071] In some embodiments of the practice of this invention also
requires that the beads be mixed with a gas substantially before
they reach the electrical excitation zones. This is the preferred
case in creating chemical functional groups, cleaning foreign
materials from particle surfaces and/or etching operations.
Introduction of non-inert gases directly into the excitation zones
may however be preferred in certain bead coating operations. Again,
in the cases of corona, plasma, glow discharge treatments (or
hybrids thereof) to carry out operations other than particle
coating, the gas is preferably an inert gas such as nitrogen, argon
and the like (as well as mixtures of such inert gases). These gases
may be placed in the electrical excitation chamber 12 under
pressurized conditions or under vacuum conditions. In case of
deposition treatments, however, the gas is preferably a non-inert
gas such as a hydrocarbon gas (e.g., an ethylene gas, methane gas
and the like) that is capable of being deposited on a given species
of polymer bead under the electrical excitation conditions existing
in the electrical excitation zones. Such non-inert gases may
likewise be employed under pressurized conditions or under vacuum
conditions. The use of mixtures of inert and non-inert gases is
also contemplated in the practice of this invention. It also should
be appreciated that overall treatments may involve use of a first
gas followed by use of a second gas. That is to say that the first
gas can be used to treat beads and then purged from the excitation
chamber. Thereafter, a second gas (then a third, fourth gas, etc.)
is introduced into the excitation chamber to perform a second
treatment function with respect to the beads.
[0072] In any case, FIG. 1 shows a stream of inert gas 34 entering
an inlet port 36 near the top of the electrical excitation chamber
12. Preferably, this inert gas injection port 36 is located far
enough above the top electrode 14 that a resulting bead/inert gas
mixture is created before said mixture flows through the uppermost
electrical excitation zone created by electrode 14. In certain less
preferred, but still operable, embodiments of this invention such a
bead/inert gas mixture can be created before even entering the
electrical excitation chamber 12. For example, they can be created
in a vessel (not shown) that is separate and distinct from the
electrical excitation chamber 12. Such particle/inert gas mixtures
also can be created in a flow directing device (e.g., flow
directing device 32) that resides within the excitation chamber 12.
FIG. 1 also depicts an embodiment of the processes and apparatus of
this patent disclosure wherein a separate and distinct gas entry
port 48 is provided for introduction of a stream of non-inert gas
50 directly into an electrical excitation zone the chamber 12.
Thus, with appropriate valving (not shown) the non-inert gas 50 can
be so introduced in place of the inert gas 34, or alternatively,
the non-inert gas 50 can be mixed with said inert gas 34 or
introduced after the inert gas is purged.
[0073] Applicant also has found that certain inert gases perform
certain functions better than others, especially in those bead
treatments calling for placement of certain desired functional
chemical groups on certain kinds of foamed beads. Nitrogen and
argon (and mixtures thereof) are particularly effective inert gases
for such purposes. Carbon dioxide can also be employed, but it is
somewhat less preferred. Indeed, some of the most preferred
treatments of this patent disclosure can be directed at improving
the adhesion qualities of certain polymeric beads--and especially
with respect to their ability to adhere to one another--through use
of tailored inert gas mixtures in the herein described
processes.
[0074] The apparatus depicted in FIG. 1 is the most fundamental
embodiment of this invention. In effect, it depicts a "batch"
apparatus and process. The apparatus necessary to carry out
continuous or semi-continuous type operations will involve more
than one (and especially three) distinct vessels interconnected in
series. At least one of these vessels may have an electrical
excitation zone comparable to that depicted in the excitation
chamber 12 depicted in FIG. 1. The excitation chamber may even
serve as a connecting vessel between vessels (e.g., between a first
and second vessel) of a three vessel series used to carry out a
semi-continuous embodiment of the herein described processes. In
such an apparatus consisting of three interconnected vessels, the
center vessel could also be considered as the electrical excitation
zone-containing vessel. The first vessel may pre-treat the
particles and/or gases for introduction into the second i.e.,
electrical excitation zone-containing vessel. The second vessel
will treat the beads and discharge them into a third vessel. These
vessels will be interconnected in ways known to those skilled in
the pressure vessel arts by valves (e.g., wobbler valves) that in
one mode allow isolation of the vessels from each other and, in
another mode, transfer of materials (particles, gases, etc.)
between the vessels.
[0075] Another goal of the bead treatments of this patent
disclosure is to obtain improved shelf life of a wide variety of
polymer beads. Indeed, applicant has found that the shelf life of
many polymeric beads can be extended from only 1 or 2 days to many
months through use of the herein described processes. This improved
shelf life is, for example, a particularly valuable attribute where
foam slurries are employed to produce foam end products. For
example, foam slurries of beads treated by the herein described
processes can be made in liquid forms that can be shipped, e.g., to
customer locations, and thereafter cured into solid foams that make
up the breathable composite materials of this patent
disclosure.
[0076] Advantages and Disadvantages of Different Types of
Treatments
[0077] One of the main general objectives of the surface treating
embodiments processes of this patent disclosure is to increase the
surface tension and/or chemical reactivity of the surface molecules
of various beads (but especially the surface molecules of
polyolefin-based polymer beads). To this end, some form of gas
ionization needs to be created in an electrical excitation zone.
This is preferably done by applying a high voltage at a high
frequency to an arrangement of two opposing electrodes insulated
from each other by a dielectric material. When properly controlled,
these conditions can create electrical fields that can ionize a gas
in a gap between the two electrodes. This can be done in several
ways under the most general teachings and scope of this patent
disclosure. For example, the amperage, voltage and/or frequency of
the power supply can be varied to produce corona, vacuum plasma,
hybrid corona/plasma and/or atmospheric plasma treatments. To these
ends, the gas pressure in the chamber can be varied in ways
hereinafter more fully described. Since hybrid corona/plasma
treatments are particularly preferred embodiments of this
invention, they will be especially emphasized.
[0078] The presence of positive or negative gas pressures in the
electrical excitation zones can also play an important role in
producing different kinds of electrical excitation zones. Each of
these various forms of electrical excitation has various advantages
and disadvantages associated with its use. By way of example,
vacuum plasma treatments use relatively low pressures to generate
especially uniform plasmas. These uniform plasmas are especially
well suited to bead decontamination operations because they create
highly uniform bead surface treatments. Conversely, corona
treatments generally employ relatively higher pressures and higher
voltage electrical discharges (relative to the voltages of vacuum
plasmas) that serve to create relatively less uniform, but more
electrically violent, excitation fields. Thus, the corona
treatments are particularly well suited to converting a given
molecule from a non-polar state to a polar state such that oxygen
molecules of other materials will be free to bond to the polar
sites on a polymer bead surface that has been corona treated
according to the teachings of this patent disclosure. That is to
say that such corona treatments can be used relatively more
effectively to increase the surface energy of a given bead surface.
The electrical discharges by corona treatments are however, highly
non-uniform in nature. It is to be particularly noted, however,
that use of applicant's relatively high voltages (e.g., relative to
those previously noted prior art devices used to treat film-like
polymers) causes no backside discharge problems with respect to
particles as they do with respect to polymer films. Indeed,
applicant has found that backside discharges can serve to advantage
in the herein described processes. Indeed, applicant has found that
non-uniformity of corona treating can serve to better treat the
backside surfaces of beads i.e., those surfaces that face away from
the electrical path between an excitation electrode and the
grounding electrode. However, applicant also has found that when
corona treatments are used alone, they do not always acceptably
treat all bead types since such treatments may be unacceptably
non-uniform in nature using some bead types.
[0079] Applicant's Preferred Plasma Apparatus
[0080] Generally speaking, a plasma is an excited gas. The excited
components (e.g., ions, electrons) that comprise a plasma will
bombard materials placed within the electrical fields created by
such plasmas, especially under low pressure or vacuum conditions.
Such particle bombardments creates surface energy, and, in many
cases, permanent changes in the surface molecules of polymer beads.
Thus, by careful selection and control of various process
parameters, a given bead's surface can be changed to fit specific
needs. One of the most important attributes of applicant's plasma
creating apparatus embodiment of this invention is its radio
frequency generator. Those having radio frequencies of about 4 MHz
are highly preferred. It also should be appreciated that, in
general, a plasma creating machine creates a high field intensity
at cooler temperatures than a corona creating machine. Indeed,
their energized field(s) is (are) only a few degrees warmer than
ambient conditions. This is not, however, the case with corona
treatments. They use a power supply to excite a gas field and
generate a great deal of heat because they treat a subject material
by bombarding it with electrical discharges or arcs rather than
radio waves.
[0081] At least, three types of plasma treatments are possible
under the teachings of this patent disclosure. First, there is
surface activation through plasma treatments. They employ gases
(e.g., oxygen, nitrogen) that modify the hydrophilicity and
reactivity of polymer surfaces. Second, there is plasma treatment
reactions that can be used in plasma induced grafting operations.
They employ inert gases (e.g., nitrogen, argon, helium, etc.) to
break polymer molecules and thereby facilitates their subsequent
cross-linking reactions. Depending on the process gas(es) used, a
variety of chemical groups (hydroxyl, carbonyl, carboxylic, amino,
peroxyl groups) can be created on the particle surface molecules.
Such grafting operations are best carried out just after the beads
pass through an excitation zone. To this end, a second gas stream
(e.g., oxygen, allyl alcohol, nitrogen) is introduced just after
excitation of the beads in order to add or graft molecules of one
or more of these gases to the surface polymer beads. This condition
facilitates covalent bonding of an adhesive material to the beads
so that they can be assembled in suitable forms (e.g., foams,
laminates, etc.).
[0082] The third general type of plasma treatment are so-called
plasma depositions wherein gases such as methane, ethane, ammonia,
tetrafluoromethane can be plasma polymerized and then used to coat
particle surfaces (e.g., to a depth of 1-10 Angstrom Units). Such
plasma depositions can utilize any gas whose molecules can be
broken and thereafter undergo polymerization within the plasma
induced zones employed in the herein described electrical
excitation apparatus. Particularly preferred gases for such
operations include nitrogen, oxygen (including ozone), ammonia and
various hydrocarbon gases such as ethylene, propylene,
organosilicon compounds (e.g., hexamethyldisiloxane,
vinyltrimethylsilane).
[0083] With these points in mind, some embodiments of applicant's
bead treatment apparatus were developed to eliminate those problems
associated with undesired higher temperatures being applied to
polymer films by prior art corona process. In effect, applicant
combines certain features of corona processes with certain features
of plasma processes. To this end, applicant uses a corona voltage
generator as a power supply because this device would generate heat
by using streams of electrical currents to excite the electrical
field--as opposed to the use of radio waves. In effect, the heat
energy given off by the current streams serves to help excite the
treatment field.
[0084] A vacuum can be used to advantage in the plasma process to
create a plasma field instead of a corona. Again, applicant has
found that combinations of corona treatments and plasma treatments
can create electrical excitation zones that are especially useful
in three dimensional treatments of polymeric beads having average
diameters from about 1 to about 4 mm. Generally speaking,
applicant's incorporation of an atmospheric plasma process into
these overall particle treatment processes is desirable because
atmospheric plasmas are up to 100 times more intense than the
plasma treatment in a vacuum. This is because, at atmospheric
conditions, the reactive gas is much denser. Thus once excited, the
ion and electron bombardments of atmospheric plasmas are much more
intense than those of corona treatments.
[0085] Process Re Foamed Beads
[0086] Polymeric expanded foam beads treated according the herein
described processes can be used to make closed cell, highly porous
foams having highly improved bead/adhesive bonding properties.
Their surface tensions before and after such treatments are shown
in table 1.
TABLE-US-00001 TABLE 1 Surface Tension Surface Tension (dynes/cm)
(dynes/cm) Before Treatment After Treatment Polypropylene 29-31
45-75 Polyethylene 30-31 45-75 Polystyrene 38 45-75 Polystyrene
(low Ionomer) 33 45-75 Polyester 41-44 45-75
[0087] Such improved bonding properties were also verified by a
series of tensile strength tests conducted on various foam
materials. These tensile strength tests were conducted in
accordance with ASTM-3475-00. In effect, the tensile strength of
foams made with electrical excitation zone treated beads (e.g.,
(beads made of polypropylene, polyethylene, etc.) was compared to
foams whose otherwise comparable beads were not treated in
applicant's electrical excitation zones. By way of example only, in
one test, a first batch of cross-linked polyethylene beads was
subjected to a corona treatment according to the teachings of this
patent disclosure. These treated beads were then combined with a
polyurethane adhesive to create a first foam material. The average
tensile strength of this first foam material was 1.67 lbs. A second
batch of otherwise comparable cross-linked polyethylene beads was
not subjected to the corona treatment. These untreated beads were
likewise combined with the same polyurethane adhesive to create a
second foam material. The average tensile strength of this second
foam material was 0.33 lbs. Thus, the electrical excitation zone
treatment served to produce a five fold increase in the tensile
strength of the first foam material.
[0088] Other Operational Parameters
[0089] Again, the effectiveness of a bead surface treatment is a
function of the electric field intensities through which the beads
pass. It can be measured in terms of changes in the surface
energies of beads after passing through these electrical fields.
Such surface energies are measured in dynes per centimeter squared.
These measurements also can be used as control functions especially
when the bead treatment apparatus are dedicated to treating the
same bead species. Of particular concern to this invention is the
fact that the surface energy of a given particle such as a
polymeric bead must be higher than the surface tension of an
adhesive that will be used to create foams and the like from an
array of such particles. For example, the surface energy of a
polymeric bead should be about 10 dynes per cm.sup.2 greater than
the surface tension of an adhesive used to combine such a bead with
comparable beads. It should be noted here that with the corona
embodiments of this invention, or the plasma embodiment of this
invention, the various surface tension values of a given particle,
at a given power density, will increase in a generally proportional
manner. However, the ultimate surface tension achieved (and amount
of increase thereof) are dependent upon the material's starting
surface tension. It also should be appreciated that variation of a
given polymeric material's response to a corona treatment is often
compounded by the loading of certain chemical additives (fire
retardants, etc.) into the polymer material. It might also be noted
in passing that the corona treatments may produce ozone when oxygen
or air is present and that the ozone may enhance such
treatments.
[0090] With just a corona, or the plasma, treatment, some polymer
materials, such as certain polyesters react more readily, accept
the treatments of this patent disclosure more readily and exhibit
more rapid increases in surface tension under relatively lower
power levels. Other materials, such as polyethylene, accept these
treatments less readily, but will exhibit a significant increase in
surfaced tension under moderately higher power levels. Some
polymeric materials, however, such as polypropylene, are difficult
to treat and may exhibit more moderate increases in surface tension
under relatively high levels of power. Smaller, higher density
beads of this kind are especially difficult to treat.
[0091] With applicant's hybrid corona (plasma process), the above
problems associated treating different kinds of beads are
minimized. Applicant has, for example, found that the hybrid
corona/plasma process of this patent disclosure usually produce at
least a 45 dyne/cm.sup.2 treatment (or better), regardless of the
polymer bead's chemistry. Thus, the apparatus for carrying out the
hybrid processes can treat otherwise difficult to treat beads
(e.g., polypropylene) from a low surface tension state to a high
enough surface tension state that an adhesive will readily bond to
a bead surface--with only one bead treatment. Thus, difficult to
treat polymers (e.g., polypropylene) will exhibit dramatic
increases in surface tension relative to the moderate increases in
surface tension produced by applicant's plasma or corona treatments
alone. Note for example that in Table 1, all of the polymer
materials (including polypropylene) are raised to the same high
levels of surface tension when comparing consistent dwell time
between 1 and 10 seconds per any given process (e.g., corona,
plasma, hybrid).
[0092] System Parameters/Material-Process Parameters
[0093] Some of the parameters of the herein described processes can
be broken down into two very general categories: system limits and
material-process limits. System parameters are governed by the
corona/plasma system and apparatus design. Material-process limits
are governed by the material, the additives in the polymeric
material and process requirements. For example, with respect to
apparatus design each type of electrode has an upper limit on the
amount of power it can accept per applicant's saucer-shaped
electrodes, their circumference. If, to achieve a certain power
density, the power supply increases beyond the electrode's maximum
rating, arcing (and hence undesired melting of polymer beads) will
occur. Additional electrodes may be added to prevent this melting.
Applicant has also found that use of stainless steel electrodes is
preferred over those made of aluminum. Generally speaking, the
higher the bead flow rate, the lower the maximum power density per
bead is achievable. Speed, being inversely proportional to power
density, impacts on the problem of increasing throughput
efficiencies.
[0094] The various surface tension values of a given material may
be influenced by several contributing factors, such as the method
of manufacture (e.g., beads expanded by use of different blow
gases), and amount of impurities which always exist in even the
highest quality polymers. If a given polymeric material is treated
at a given power density, its surface tension will be increased in
a generally proportional manner. However, both the ultimate surface
tension achieved and amount of increase are dependent upon the bead
material's starting surface tension. It might be again noted that
variation of a given polymeric material's response to corona/plasma
treating is often compounded by loading certain additives such as
fire retardants into such polymers.
[0095] As mentioned earlier, different polymeric materials or
substrates react differently to corona/plasma treating. Some
polymer materials, such as certain polyesters react more readily,
accept the treatments of this patent disclosure more readily and
exhibit more rapid increases in surface tension under relatively
lower power levels. Other materials, such as polyethylene, accept
these treatments less readily, but will exhibit a significant
increase in surface tension under moderately higher power levels.
Finally, some polymeric materials, such as polypropylene, are more
difficult to treat and may exhibit only moderate increases in
surface tension under relatively high levels of power.
Polypropylene beads are often relatively more difficult to surface
treat, especially smaller, higher density beads of this chemical
type.
[0096] Continuous Bead Treatment
[0097] These particle treater processes can be adapted to treat
beads in a continuous or semi-continuous manner. To this end,
particles can be drawn into a top vessel (e.g., a top vessel of an
interconnected three vessel series) by placing a vacuum in said top
vessel. Vacuum pumps will extract the air pulled into the top
vessel with the beads and thereby keeping the entire system at a
steady state vacuum condition e.g., at approximately 20 torr.
Nitrogen or a mixture of inert gases will then be injected around
the electrodes. This gas will be used to keep the plasma field
exited. Some of the outside air will mix with such nitrogen as a
benefit to creating more reactive sites on the polymeric beads.
When a bottom vessel of a vessel series is full, a valve will
close. The bottom vessel will be pressurized to ambient pressure
and the particles will be removed. Once the beads are removed, the
bottom vessel will be evacuated (e.g., to about 20 torr). A valve
between a 2.sup.nd and a 3.sup.rd vessel will open. Beads being
treated during this time fall into the 2.sup.nd vessel and are
collected there until the valve reopens. Once the valve is opened
these particles will fall into the 3.sup.rd vessel. This process
will continue until the bottom vessel is once again full. The cycle
will then repeat. In some particularly preferred embodiments of
this invention, an excitation chamber can serve to interconnect two
vessels e.g., a first (top) and a second (center) vessel.
[0098] Surface Treatment of Foamed Beads
[0099] Again, the processes and apparatus of this patent disclosure
can be especially adapted to improve a polymer bead's wetting
properties. These properties especially influence how well adhesive
coatings will flow over a bead's exterior surface. Thus, improved
wetting properties, will enhance bonding between such beads when
they are used to create shaped forms such as those foams used to
make various three dimensional, shaped products. Generally
speaking, if a bead's surface energy is lower than the surface
tension of an adhesive placed on the bead, the adhesive will bead
up and not adhere well to the polymeric bead. Conversely, when the
bead's surface energy is higher than the adhesive's, the adhesive
will effectively wet out around the bead, flowing out uniformly and
providing maximum contact with other beads. This circumstance leads
to improved adhesion between beads.
[0100] Most adhesives resist wetting on the surface of
virgin-plastic beads, which are characterized by an inert,
non-porous, low-energy surface. Moreover, many virgin-plastic
beads, are made from polyethylene and polypropylene. Beads of these
types tend to be very slippery and feel greasy to the touch.
Getting coatings to permanently adhere to them is a relatively more
difficult task. Thus, one goal of the surface treatments of this
patent disclosure is to ensure that an applied durable adhesive
coating will withstand any conditions or environments that the
beads (and hence the shaped products made from them) might face.
These conditions may include exposure to the elements outdoors,
regular cleaning with detergents, and extremes in temperature and
the like.
[0101] Electrical Power Characteristics of Preferred Surface
Treating Apparatus
[0102] One widely used prior art preferred power supply unit for
carrying out corona treatments on films is a 4 MHz, 60 milliamp
system which uses a spinning electrode wheel assembly rotating at
3600 rpms to supply voltage spikes to a 4 MHz resonant frequency
coil. Such a power supply unit will accept 50/60 Hz utility power
and convert it into a single phase, higher frequency power. Such
devices will preferably have one variable digital volt meter and
digital ammeter to vary input voltage and milliamps. Most prior art
corona treaters operate nominally between 10 to 30 kHz because at
higher frequency levels, heat generation and back treatment become
major concerns in their prior art applications--i.e., when surface
treating films. Again, both heat generation and backside treating
are undesirable when treating films, and thus have limited how
corona treaters have been used in the past. These facts and
circumstances are to be contrasted with the bead treater apparatus
of this patent disclosure which preferably operates at about 250
kV. Such higher voltage levels have several advantages in the
particle treatments of this patent disclosure. For example, at such
higher voltages, power can be supplied to at least three tandem
electrodes without arcing. It also is important when treating 3
dimensional beads that a uniform plasma be generated to get
backside treatment as well as generate some heat to help intensify
the electrical field--because this serves to boost bead throughput.
It should also be appreciated that in the practice of this
invention, treatment rates (lbs/hr) and tensile strengths may be
related. For example, some foams show an increase in strength at
100 lbs/hr of around 600 percent. With variable voltage generators,
one can vary the input voltage to change the output voltage. By
changing the input voltages one can change the input current
resulting in an increase in the power density of the plasma field.
For example, an input current can be varied from 0.1 milliampere to
3 amps.
[0103] Operational Variations Between Corona Treatments, Plasma
Treatments and Hybrids Thereof
[0104] If the particle treatment apparatus of this patent
disclosure is not provided with vacuum conditions within their
electrical excitation chamber(s), they will generally constitute
the corona treater embodiments of this invention. Such corona
treatments will commence by turning on a voltage generator and
sending a current going through a Tesla coil (e.g., a resonant
frequency coil). Preferably, this current will be between about 0.2
milliamperes and about 3 amps. An even more preferred current
setting would be between about 0.3 and about 0.6 milliamperes. A
flow of particles, beads, etc. is then sent through the resulting
corona field. Optimum flow rates of particles (such as polymer
beads) through the corona field would preferably be predetermined
e.g., by treating comparable particles at different flow rates and
then spraying the resulting bead samples with a dyne solution to
determine their surface energy. Such dyne surface treatment kits
are commercially available.
[0105] By way of example only, the surface energy of many polymer
beads is preferably made greater than about 45 dynes per square
centimeter by the herein described processes. In most cases, it
would not be necessary for such beads to have surface energies
greater than about 75 dynes per square centimeter for successful
practice of this invention. The preferred surface energy for most
of the more preferred polymer beads will be about 55 dynes per
square centimeter. Such surface energy levels are especially
preferred when the surface of the beads are exposed to a liquid
adhesive. It should also be noted that an electrical zone-excitable
gas environment need not be continuously supplied within the
excitation chamber for a typical corona treatment process.
[0106] By way of contrast, the plasma treater embodiments of this
invention use a radio frequency generator to create their
electrical excitation zone(s). The radio frequency is preferably
between about 3 MHz and about 5 MHz. Most preferably, the frequency
will be about 4 MHz. Such plasma type treaters provide a cold
treatment means because the energized field will normally only be a
few degrees warmer than ambient conditions when energized by, for
example, 4 MHz radio waves. In order to better convert the
apparatus of this patent disclosure into their plasma treater
embodiments, vacuum conditions are put on their electrical
excitation zone(s). The vacuum level will preferably be in the
range of about 5 torr to about 50 torr. An electrically excitable
gas (e.g., argon or nitrogen) will then be injected into the
excitation chamber to create a plasma field. The hybrid
corona/plasma treat embodiments of this invention also involve
placing a vacuum in the excitation chamber. In these corona/plasma
embodiments, the principle reason for a vacuum to be present in the
excitation zone(s) is that there is usually not enough energy
supplied by a radio frequency generator to energize a gas at
pressures greater than about 100 torr.
[0107] It should also be noted that when a gas is injected into the
excitation chamber, the vacuum gauge reading on a plasma treater
will preferably go to about 20 to 50 torr. This is an increase in
pressure from a preferred pump down pressure of about 5 to about 30
torr. In the case of the use of particle treatment apparatus having
multiple vessels--especially those multiple vessel systems used to
carry out continuous, or semi-continuous, operations (as opposed to
the batch type operation depicted in FIG. 1). It might also be
noted in passing that a top and a bottom vessel of a vertically
arranged, three vessel embodiment of this invention, need not be
pressure vessels because they would not see vacuum pressures. Be
that as it may, the next step in such an operation would be to
start the radio frequency generator component of the apparatus.
Again, the radio frequency generator would preferably transmit a
radio wave at about 4 MHz exciting the whole volume of the
electrical excitation chamber of FIG. 1, or the second or center
vessel of an apparatus comprised of a top vessel, center vessel and
bottom vessel that may constitute a continuous (or semi-continuous)
treatment embodiment of the apparatus of this patent disclosure. In
any case, the electrically excited zone(s) will manifest themselves
by a soft purple glow. Beads need not, however, flow continuously
through this excitation field but, alternatively, can remain in the
electrical excitation zone of the center vessel (or chamber such as
that depicted in FIG. 1) until they are sufficiently treated. The
amount of time to treat different bead polymer chemistries will
vary. Preferred treatment times though, will generally vary between
about 6 to about 12 minutes using just the plasma process. The
estimated volume of a site glass area in a three vessel system is
preferably from about 2 to about 3 gallons (or 7 to 10 liters). In
any case, once the beads are adequately treated they will be
released from a treatment vessel (e.g., the excitation chamber
depicted in FIG. 1); or they will be released from a center vessel
into a bottom vessel below a center or site glass vessel. The
process can then be repeated.
[0108] If the corona process is combined with the plasma process of
this invention, the resulting process can begin by pumping the
center vessels (or the chamber depicted in FIG. 1) down to
preferably about 20 torr. This pressure may, however, range from
about 5 to about 50 torr. A voltage is then applied. The voltage
generator also is preferably set to deliver the desired voltage at
a current level of about 0.4 milliamperes. This amperage can
however range from about 0.2 to about 3 amps. A purple glow would
be seen in a site glass area of the excitation chamber around each
electrode. It will generally extend outward toward a grounding
strap. The gas flow would then be started. The gas flow would be in
the range of 5 to 20 cubic feet of gas per hour. The preferred
setting would be at about 10 cubic feet per hour. A vacuum pump
control system can then be used to adjust the vacuum pump intake
valve(s) to keep the system at a preferred steady state pressure
e.g., at about 20 torr of pressure.
[0109] Leaving the vacuum pumps of this apparatus running during
the hybrid corona/plasma treatment may facilitate several important
advantages. First, by replenishing the gas, dirt and loosely linked
polymers are swept away and exhausted to atmosphere. Second, a
constant fresh source of gas is provided to the treatment field.
Thirdly, if chemical deposition on beads surfaces using a polymer
gas in conjunction with the excitable gases is desired, this is
where and when this deposition process is best carried out. Fourth,
a bottled gases can be used to cool the treatment field if
necessary. In any case, an operator can then lower a wobbler valve
(as described in the corona process) and set the revolutions of the
valve. Here again, about 100 to 300 revolutions per minute (rpm)
can be employed, with a 200 rpm speed being preferred. Applicant
also has found that bead treatment rates can vary according to the
bead chemistry, but the preferred range for most polymer beads will
be between about 75 and about 300 pounds per hour with a particle
treatment apparatus employing the 756 Watt power source previously
noted. In the multivessel, continuous treatment embodiments of this
invention once the beads contained in excitation vessel are treated
and sent to the lower vessel, said lower vessel can be emptied and
the process repeated.
[0110] Electrode Design
[0111] The particle treater shown in FIG. 1 is shown provided with
three electrodes 14, 16 and 18. Each is precision machined and
sized to prevent arcing from the electrode to the grounding strap
20. Experience has shown that any imperfection along the edges of
the electrodes encourages formation of undesired arc paths. If an
arc path is established, beads located within said path will be
melted and bead flow through the particle treater will eventually
stop. Once an arc path is established, the plasma field will also
be lost or greatly reduced. Beads passing through other areas of
the field will therefore not receive good surface treatments. Foam
product made from arc-damaged beads will be brittle and have
greatly reduced tensile and tear strength. Thus, great care should
be taken to prevent formation of such electrode edge
imperfections.
[0112] It also should be noted that each electrode in FIG. 1 is in
tandem, and has a different diameter in a descending order D.sub.1,
D.sub.2, D.sub.3, etc. order of size. This arrangement may seem
counter intuitive, i.e., that the smallest (i.e., 6 inch) electrode
is the furthest away from the ground strap 20 and furthest away
from a resonant frequency coil located near the top of the device.
Applicant has, however, found that as the circumference of these
saucer-shaped electrodes decreases, the distance from the grounding
strap preferably increases. Moreover, when the electrodes reside in
a vacuum, the distance from the electrode to the grounding strap is
not nearly as critical as when the electrodes were located in an
air atmosphere because air impedes electron flow. Applicant's
experimentation has also shown that if the electrodes are of the
same circumference only one of the three electrodes would be able
to generate a suitable field. Moreover, applicant has found that if
the electrodes are reversed, relatively less desired results would
tend to occur. In effect, only one electrode is able to generate an
effective field. If more power is added to the electrodes, arcing
will emanate from the electrode generating that field.
[0113] Table 2 is a matrix of some of the more preferred power,
voltage, frequency and air pressures used in various embodiments of
this invention.
TABLE-US-00002 TABLE 2 Hybrid Corona Plasma Corona/Plasma Watts 756
W 756 W 756 W Volt 250 kV 250 kV 250 kV Freq. 3 MHz 4 MHz 4 MHz
Vacuum Atmospheric 5 torr - 1 Atm 5 torr - 1 atm
[0114] Continuous Treater Vessel Systems
[0115] The treaters can also be designed for continuous treatment.
To this end an array of serially interconnected vessels (e.g.,
three vessels connected in series) are attached to a common frame.
The top vessel can be separated from the lower vessel by
hydraulics. This is necessary in order to work on the electronics
located within the treater vessel. Nitrogen or argon gas can be
currently injected into an upper vessel just above the electrical
excitation zone. A gas ring can be employed to distribute the gas
around the outside diameter to position the gas and help the
electrodes create a plasma field in the device.
[0116] Gas Ring of Continuous Treaters
[0117] A gas ring can be located just above a treatment area. The
gases can be controlled with mass flow controllers. The gases are
introduced into the evacuated chamber and maintained at a reduced
pressure by a vacuum pump and throttle valve. After the gas
pressure is stabilized, e.g., at approximately 20 torr, the gas is
energized by the 4 MHz coil. A vacuum system can be used to pull
the gas through the beads as they are being treated. The vacuum
system also removes unwanted impurities and gases produced by the
plasma bombardment.
[0118] Wobbler Valves f Continuous Treaters
[0119] (1) One or more wobbler valves can be used to advantage in
the practice of this invention. They are especially useful in
embodiments of this invention involving continuous processes
employing a series of vessels. Generally speaking, these valves can
travel in a concentric circle to keep beads flowing in the throat
of the apparatus of this patent disclosure. For example, beads can
flow by gravity from a top vessel through the remainder of a
multivessel apparatus for carrying out the herein described
treatments. The wobbler valve restricts the flow of the beads so
that each bead is in the excited plasma field for a given period of
time determined by experimentation and type of bead polymer
chemistry. To improve process bead flow, such a wobbler valve can
be made to rotate or spin while traveling in a concentric circle.
Use of wobbler valves that do not rotate is possible, but less
preferred. The rate of rotation is preferably adjustable e.g., 1
from about 100 rpm to about 300 rpm. An air motor that is adjusted
by varying the input air pressure can power the head of the valve
doing the rotating. The air motor replaces an electric motor
because the electrical field generated in a plasma field would
magnetize the small motor over time and eventually preventing
operation. Rotation of such a valve also provides a means to tumble
the beads as they move downward through the plasma field insuring
that an even surface treatment is established on each bead.
[0120] Representative Polymer Materials
[0121] The term "polymer," as used herein, includes homo-polymers,
co-polymers and/or their blends and alloys with other polymers
and/or natural and synthetic rubbers, and polymer matrix
composites, on their own, or alternatively as an integral and
uppermost part of a multi-layer laminated sandwich comprising any
material e.g. polymers, metals or ceramics, or an organic coating
on any type of substrate material. The term "polymer" also should
be taken to include thermoset and/or thermoplastic materials. By
way of examples only, the polymeric materials which can be surface
modified by applying the present invention include, but not limited
to, polyolefins such as low density polyethylene (LDPE),
polypropylene (PP), high density polyethylene (HDPE), ultra high
molecular weight polyethylene (UHMWPE), blends of polyolefins with
other polymers or rubbers; polyethers, such as polyoxymethylene
(Acetal); polyamides, such as poly(hexamethylene adipamide) (Nylon
66); halogenated polymers, such as polyvinylidenefluoride (PVDF),
polytetra-fluoroethylene (PTFE), fluorinated ethylene-propylene
copolymer (FEP), and polyvinyl chloride (PVC); aromatic polymers,
such as polystyrene (PS); ketone polymers such as
polyetheretherketone (PEEK); methacrylate polymers, such as
polymethylmethacrylate (PMMA); polyesters, such as polyethylene
terephthalate (PET); and copolymers, such as ABS, ethylene
propylene diene mixture (EPDM).
[0122] Padding Material Components
[0123] FIG. 13 depicts a basic building unit of one of the more
preferred padding materials of this patent disclosure. This
particular basic building unit is a solid, electrical excitation
zone-treated bead 24 that is spherical in shape and substantially
uniformly covered by a layer 26 of an adhesive material. This
spherical configuration of the bead 24, and uniformly thick 25
adhesive coating 26, can be thought of as an "idealized" system.
Those skilled in this art will however appreciate that commercially
available beads may well have other configurations, idealized or
otherwise (e.g., truncated spheres, ellipsoids, truncated
ellipsoids, cubes, cylinders, tear drop shapes and the like). For
example, several representative bead configurations that can be
used in making applicant's padding materials are shown in a product
brochure published by Porex Technologies Corp. (Fairburn, Ga.)
entitled "Porex.RTM. Porous Plastics High Performance Materials"
and said brochure is incorporated herein by reference.
[0124] Be the bead sources as they may, must be made of materials
that will respond to the pretreatments of this patent disclosure so
that bonding qualities between the bead's outer surface and the
adhesive layer placed on that outer surface in order to make the
padding materials of this patent disclosure. Such beads can, for
example, be made of inelastic materials or elastic materials. For
the purposes of this patent disclosure the term "inelastic" can be
taken to mean the bead's inability, upon deformation, to
substantially return to its original shape. In other words, the
material has no so-called "memory" as to its former
(pre-deformation) shape. Conversely, the term "elastic" can be
taken to mean a bead material having a memory, and hence the
ability to return to its original shape after being deformed.
[0125] Whatever their shape, construction material, degree of
elasticity or surface treatment experience, the electrical
excitation zone-treated, beads of this patent disclosure generally
will have (on average) a diameter D.sub.1 (as measured on a bead's
longest dimension--see for example D.sub.1 of the ellipsoidal bead
of FIG. 15) ranging from about 1 mm to about 6 mm. Beads having
average diameters ranging from 1 to 3 mm are, however, somewhat
more preferred. It is even more preferred that the beads of this
patent disclosure have average diameters ranging from about 1.5 to
about 2.5 mm. In some of the more preferred embodiments of this
invention, these beads, no matter their size, shape or method of
manufacture will be made from plastic or phenolic resin materials
in ways well known to those skilled in the bead making arts. By way
of example only, a useful representative method for making round
beads is taught in U.S. Pat. No. 4,441,905 ("the '905 patent").
Hence, the teachings of the '905 patent are incorporated herein by
reference. Other useful representative bead manufacturing methods
are taught in U.S. Pat. Nos. 4,989,794; 4,751,203; 4,751,202; and
5,292,840. Again, some of the most preferred resin compositions for
the manufacture of applicant's beads will include polystyrene,
polyethylene, polypropylene and especially ethyl propylene
copolymers ("epps").
[0126] The electrical excitation zone-treated bead 24 shown in FIG.
13 is depicted, in cross section, as being a solid that is provided
with a layer of adhesive material 26 that substantially uniformly
coats the entire outer surface of the spherical bead 24. The
thickness 27 of such a coating of adhesive material 26 preferably
will range from about 5.times.10.sup.-6 mm to about 2 mm. Thus,
upon curing of the adhesive, the overall diameter D.sub.2 of the
idealized, bead/adhesive layer system shown in FIG. 13 will
preferably range between about 1 mm and about 10 mm. Again, in some
of the more preferred embodiments of this invention, the diameter
of the beads will range from about 1 mm to about 3 mm. and the
thickness of the adhesive layers coated thereon will range from
about 5.times.10.sup.-6 mm to about 2 mm. Hence, such fully coated
beads may range in size (left side coating layer, plus bead
diameter, plus right side coating layer) from about 1 to about 7
mm. Again, the adhesive layer placed on applicant's beads may be of
substantially uniform thickness--or of varying thickness. To some
degree, such uniformity will depend upon the method (auger mixing,
spraying, immersion, etc.) by which the bead is coated.
[0127] Again, the solid, spherical bead 24 in FIG. 13 is shown
completely covered with a layer of adhesive 26 of substantially
uniform thickness 25. This idealized circumstance is to be
contrasted with the spherical, two-layered bead 24' shown in FIG.
14 wherein said two layered bead 24' is only partially covered
(e.g., about 50% of its surface area) by an adhesive layer 26'
whose thickness 27, (27') is not uniform. That is to say that the
adhesive layer 26' shown in FIG. 14 has a greater thickness 27 on
the far left end of the bead than its thickness 27' on its upper
left side. The right side of the bead is shown having no adhesive
coating whatsoever.
[0128] By way of another departure from the idealized bead/adhesive
system depicted in FIG. 13, FIG. 15 illustrates, in cross section,
an embodiment of this invention wherein the electrical excitation
zone-treated bead is an ellipsoidal solid 24''. It is shown
provided with a layer (of varying thickness) of adhesive 26 on
about 80 percent of its surface area. Again, many different bead
body configurations can be used in the practice of this invention
(e.g., truncated spheres, truncated ellipsoids, cubes, bar-like
configurations, cylinders, tear drop configurations and the like).
This all goes to say that the coated beads of this patent
disclosure may have a wide variety of geometric shapes (or mixtures
of geometric shapes) so long as their longest dimension is between
about 1 and about 10 mm. It might also be noted in passing here
that this invention contemplates use of (1) different shaped beads,
(2) different sized beads, (3) beads of different construction
materials, (4) beads provided with varying thicknesses of different
kinds of adhesive materials, (5) solid beads, (6) hollow beads, (7)
beads having holes through their bodies, (8) use of coupling agents
to aid bead/adhesive bonding (e.g., use of titanates and silane for
this purpose) and mixtures of beads having any combination of the
just noted attributes (1) to (8) in the same padding material.
[0129] FIG. 16 shows a system of four solid, coated beads (1, 2, 3
and 1') in an idealized, two dimensional, row-like, orientation.
Those skilled in this art will appreciate that, in actuality, these
beads will display the hereinafter described row-like features in a
three dimensional sense. In any case, in FIG. 16, the space between
beads 1 and 2 is shown filled in with an adhesive material 26.
Similarly, the space between beads 2 and 3 is shown filled in with
adhesive material 26. The space between bead 3 and sequence
repeating bead 1' is however shown as being a void space 20. Thus,
it can be said that every third bead is provided with a void space.
This is the preferred minimum requirement for the void spaces of
the padding materials of the present patent disclosure to be
considered as being "regularly spaced" as this term is used in this
patent disclosure.
[0130] FIG. 17 shows a more preferred embodiment of this invention
wherein every second bead is regarded as being regularly provided
with a void space. This is a more preferred form of "regular"
spacing of the void spaces in applicant's padding materials. FIG.
17 also shows an embodiment of this invention wherein bead 1 is a
hollow bead, bead 2 is a solid bead and bead 1' is a hollow bead.
Thus the overall system can be regarded as a mixture of hollow and
solid beads bound together according to the teachings of this
patent disclosure. Those skilled in this art will, of course,
appreciate that hollow beads also are well known to this art. For
example, the previously cited '905 patent shows how hollow or solid
beads can be made using various versions of the thereindisclosed
technology. Moreover, the outer shells of applicant's hollow beads
may be made of inelastic or elastic materials. Thus, the term
"elastic" is not necessarily premised on the bead being hollow, but
rather on the elastic nature of the bead forming material.
[0131] FIG. 18 depicts a still more preferred embodiment of this
invention where substantially every bead (e.g., beads 1, 2 and 1')
is provided with a void space e.g., void spaces 20 in a three
dimensional sense. This is the most preferred form of "regular"
void spacing according to the teachings of this patent disclosure
and to some degree represents a highly idealized embodiment of this
invention.
[0132] FIG. 19 shows a generalized system of another highly
idealized bead/adhesive/void space system. The individual beads 1,
2, 3, 4, 5, 6 and 7 therein are shown to be solid in nature and
substantially fully coated with respective, uniformly thick, layers
of adhesive, i.e., layer 26(2) on bead 2, layer 26(3) on bead 3,
etc. Thus, these beads can be thought of as being a part of a
coherent, three dimensional, body by virtue of the fact that most
of their respective adhesive coatings are in physical contact
with--indeed melded with--the adhesive coatings of adjacent beads
in that body. That is to say that the adhesive coatings of adjacent
beads adhere to each other, in large part, by virtue of a bonding
action between their originally liquid adhesive coatings. These
coatings generally extend from the bead system's
adhesive-to-adhesive contact or meld regions around a major portion
of a given bead. Consequently, the beads are bonded to each other
at the points of contact of their respective adhesive coatings. For
example, in FIG. 19 bead 1 is bonded to the beads (1-7) by the
adhesive-to-adhesive contact points 1(2), 1(3), 1(4), 1(5), 1(6)
and 1(7). This adhesive-to-adhesive bonding action can be brought
about by simply drying "wet", "liquid" (or "semi-liquid") or
"tacky" adjoining adhesive coatings in ambient conditions. Such
drying also can be accelerated by thermal or electromagnetic wave
treatments of the wet or tacky adhesive coatings on adjacent coated
beads.
[0133] In any case, applicant has found that such
adhesive-to-adhesive bonds withstand impact type forces much better
than bead-to-adhesive bondings or bead-to-bead bondings. Hence one
of the underlying principles of this invention is to assure that a
large percentage (e.g., at least 50%, preferably at least 80% and
most preferably substantially 100%) of the beads are provided with
such adhesive-to-adhesive bondings. This melding at their
adhesive-to-adhesive contact points is preferably brought about by
contacting the adhesive composition with the beads while said
adhesive is at a temperature of about 20.degree. F. to about
200.degree. F. Most preferably this contact will take place when
the adhesive is at temperatures ranging from 50.degree. F. to
150.degree. F. In any case, the adhesive-to-adhesive system created
by these adhesive bonds becomes a subsystem within the overall
bead/adhesive/void space system. Given the presence of this
adhesive-to-adhesive system, impacts upon materials made from such
a bead/adhesive/void space system are to a large degree distributed
through the body of adhesive material coated on the outside
surfaces of the coated beads.
[0134] As previously noted, a most important aspect of this
invention also resides in the fact that the void spaces 20, 20',
20'', etc. shown in FIG. 19 exist between various subsets of the
bead/adhesive system on the substantially "regular" bases
previously described after the adhesives on adjacent beads have
been bonded to each other. This regularly appearing void space
system gives applicant's padding materials those porous, breathable
qualities that are especially desired in padding used in athletic
or medical equipment. In other words, the drying or curing of the
adhesive layers on the beads is such that the void spaces 20, 20',
20'', etc. shown in FIG. 19 are not substantially filled in with
the adhesive material in the manner that the prior art bead systems
depicted in FIGS. 8, 9, 10 and 11 of this patent disclosure are
filled in with a polymeric material.
[0135] It also should be noted the applicant's void spaces are more
regularly spaced than the void volumes 20 appearing in FIGS. 12 and
12(a). This regularity also tends to place applicant's void volumes
in direct fluid communication with each other relative to the void
volumes depicted in FIGS. 12 and 12(a). Again, the regularity and
fluid communication in applicant's padding materials follows in
large part from the fact that applicant contacts his adhesives with
his beads while the adhesive is in a liquid state that does not
involve melting of the adhesive components of applicant's
formulations. Again, by way of contrast, the bead/resin/void space
systems depicted in FIGS. 12 and 12(a) are produced by melting dry
resin particles while they are in the presence of the hollow
microbeads of that material.
[0136] Applicant also has found that the presence of such
substantially regularly spaced void spaces (in three dimensions)
can be so created when the amount of adhesive coated upon (e.g., by
auger mixing, spraying, immersion, etc.) a given amount of beads
represents from about 20 weight percent to about 80 weight percent
of the resulting padding materials of this patent disclosure. More
preferably, applicant's adhesive/total padding material weight
ratio will be such that the adhesive will represent from about 40
to about 60 weight percent of a given end product padding material.
That is to say that such weight ratios will exist after the
adhesive has fully dried or cured to an extent such that virtually
all of its volatile components have departed.
[0137] By way of an example of the effects of changes in the
amounts of adhesives used in these formulations, applicant has
determined that when beads (solid or hollow beads, made from
inelastic or elastic materials) having diameters ranging from about
1 mm to about 6 mm are coated with an amount of adhesive that upon
drying or curing, constitutes about 40 weight percent of the
resulting padding materials, at least about 50% of the beads have
surface areas that are at least about 50 percent covered with the
said adhesive. Such padding materials also will have void volumes
of from about 10 to about 40 volume percent of the total volume of
the resulting padding material i.e., the volume of the overall
bead/adhesive layer/void volume system. When however, the same
beads described in the previous example were mixed with an amount
of adhesive that, upon drying, constituted about 50 weight percent
of applicant's end product materials, about 90% of the resulting
adhesive coated beads will have surface areas that are at least 80
percent covered with the adhesive and the void volume of the
materials still falls well within the lower end of desired 10-40
volume percent level. Applicant also would note in passing that
adhesive percentages (50-60 weight percent) that produce void
volumes of about 30 to 35 volume percent are somewhat more
preferred in the practice of this invention.
[0138] Applicant also has established that there is an upper limit
to this adhesive/bead weight ratio. Generally speaking, applicant
has determined that if a padding material otherwise made by the
teachings of this invention is comprised of more than about 80
weight percent (or more than about 5 volume percent) of adhesive,
the void volume of that padding material becomes, in effect,
"filled in" by the adhesive. Such circumstances are generally
depicted in the prior art related FIGS. 8-12 of this patent
disclosure. Thus, these prior art figures also depict "excessive"
use of the adhesive according to the teachings of the present
patent disclosure. Again, this follows from the fact that the
resulting padding material loses one of its most important
attributes for some applications--its breathability--when its void
spaces are filled in by the adhesives. Hence, applicant prefers to
use the adhesive materials in amounts such that the void spaces in
the resulting material will represent at least about 10 percent of
the padding material's entire volume. Padding materials having void
volumes ranging from about 30 to about 40 volume percent of the
total volume of the resulting padding material are even more
preferred. To this end, applicant has found that the adhesives in
these padding materials (in the adhesive's cured form) will, most
preferably, constitute no more than about 60 weight percent of the
end product padding material.
[0139] Many of applicant's more preferred padding materials use
adhesives that are far more dense than the bead materials. For
example, in one particularly preferred polystyrene/adhesive
formulation used in the practice of this invention, applicant has
found that use of 1% (by vol.) more of the adhesive produced a 25%
gain in the weight of the resulting padding material. Use of 2% (by
vol.) more adhesive produced a 39% increase in the padding
material's weight. Similarly, use of 3% (by vol.) more adhesive led
to a 48% increase in weight while use of 4% (by vol.) more adhesive
usage produced a 55% weight gain in the end product material.
[0140] Applicant also has found that use of more than about 5% (by
volume) of adhesive in the padding materials of this patent
disclosure produced end products having rather poor breathing
qualities. That is to say that applicant has found that use of more
than about 5 volumes percent adhesive in the padding material of
this patent disclosure tends to clog or fill in the void volumes to
such a degree that they lose much of their breathing qualities. It
might also be again noted that the higher densities of the
adhesives relative to the beads used in the practice of this
invention are such that the above noted 5% by volume adhesive
generally corresponds to a padding material comprised of about 80%
by weight adhesive. Thus, applicant's invention calls for the use
of adhesive components that represent from about 10 to about 80
weight percent of the resulting padding material. This range
generally corresponds to use of about 1 to 5 volume percent
adhesive in the padding materials of this patent disclosure.
[0141] FIG. 19A depicts a departure from the idealized
bead/adhesive/void space system shown in FIG. 19. Beads 1, 2 and 7
in FIG. 19A are shown in circumstances wherein these three beads
are not completely covered by a uniform layer of adhesive.
Moreover, bead 7 is shown partially melded into the bodies of beads
1 and 2. Thus, beads 1, 2 and 7 are associated with each other by
this melding of the bead material rather than by the melding of an
adhesive coating on the contact regions of these particular beads.
In effect, the void space 20'' shown in FIG. 19 has been filled in
by the partially melded bodies of beads 1, 2 and 7 depicted in FIG.
19A. Moreover, bead 7 is no longer attached to bead 6. FIG. 19A is
employed to show that occasional occurrences of this bead-to-bead
melding can be tolerated in applicant's padding materials to some
degree. It can not however predominate. Thus, in the more preferred
embodiments of this invention, the remaining void volume of
applicant's padding material shown in FIG. 19A (i.e., void spaces
20, 20', etc.) should still constitute at least 10 volume percent
of the padding materials of this patent disclosure. That is to say
that even if some bead-to-bead melding has taken place (and, hence,
filled in void volumes such as that depicted by item 20'' of FIG.
19) this bead-to-bead melding will not take place to such an extent
that the void volume of the padding material will be less than
about 10 volume percent.
[0142] FIG. 20 depicts another idealized bead/adhesive/void space
system made according to the teachings of the present invention
wherein the beads are of the same size, but are not made of the
same material. For example, beads 1 and 8-19 are depicted as being
made of a material different from the remainder of the beads.
Moreover, beads 2, 4 and 6 are depicted as being made from
materials different from beads 3, 5 and 7. Moreover, some of these
beads may be hollow (e.g., beads 10, 13, 16 and 19) while others
are solid. Moreover, some of these solid beads may have holes
passing through their otherwise solid bodies (see for example,
beads 11, 14 and 6). These holes may allow air to pass through some
of the beads and thereby add to the breathability of the overall
padding material. It also should be noted that regardless of
whether the beads are solid, hollow or solids having holes they can
be made of inelastic materials while others are made of elastic
materials. The resulting system should, however, still be
characterized by the presence of regularly spaced void spaces 20,
20', 20'', etc. that constitute at least about 10 volume percent of
the material and by the fact that all of the adhesive-coated beads
in this mixed bead type system will have average diameters ranging
from about 1 mm to about 10 mm.
[0143] FIG. 21 depicts a bead/adhesive/void space padding material
of this patent disclosure wherein some of the beads are of
different sizes. Moreover, some of these different-sized beads are
solid while others are hollow and while still others are depicted
as being made of materials different from the remainder of the
beads. Solid bead 4 is shown having a hole 4(1) passing through its
diameter region. The same is true of bead 11 which has a hole 11(1)
passing through its diameter region. Bead 13 has two such holes
13(1) and 13(2) passing through its bead body. The
bead/adhesive/void space system shown in FIG. 21 also indicates
that some of the beads (e.g., beads 3, 9 and 10) are not covered by
any adhesive coating. Preferably less than 20 percent--and more
preferably less than 10 percent (by weight), and most preferably
less than 5 percent (by weight)--of the beads in a given padding
material of this patent disclosure will fail to be at least 50
percent coated with an adhesive.
[0144] In any case, those skilled in this art also will appreciate
that by blending beads of various sizes, the volume of the
individual voids or interstitial spaces can be varied. By way of
example, the void spaces 20' and 20'' shown in FIG. 21 are shown to
be considerably larger than the "idealized" void volumes 20, 20',
20'' etc. shown in FIG. 19. Those skilled in this art also will
appreciate that the idealized void volumes 20, 20', 20'', etc.
shown in FIG. 19 represent about 26 volume percent of the
idealized, theoretical system depicted in FIG. 19 wherein all of
the spherical beads are assumed to be of a uniform size. Thus, the
spaces 20' and 20'' shown in the bead system of FIG. 21 represent
the means by which applicant's padding materials can have void
volumes that are greater than, or less than, the theoretical 26
volume percent of the idealized system shown in FIG. 19. For
example, if the relatively large void spaces 20' and 20'' shown in
FIG. 21 were of such relative sizes, the resulting padding material
could have a void volume greater than the theoretical 26 volume
percent of the system shown in FIG. 19. On the other hand, if the
relatively large void spaces 20', 20'' in FIG. 21 are to a large
degree filled in with the adhesive material, the void volume of the
resulting system can be less than the theoretical 26 void volume
percent of the idealized system of FIG. 19. Again, the adhesives
used to make applicant's padding materials are used in quantities
(to weight percent of the resulting padding material) such that the
void volumes of applicant's padding materials will range from about
10 to about 40 volume percent with void volumes of about 30 to 35
volume percent being somewhat more preferred.
[0145] Applicant has found that one simple, straightforward method
by which the adhesive-to-adhesive bonding action, bead/adhesive
weight ratio and void space requirements can be achieved is by
mixing the liquid adhesive with the beads in an auger type mixing
and conveying device known to those skilled in this art. In effect
the liquid adhesive is accurately metered into an auger-driven flow
of the dry beads in order to thoroughly mix and blend the liquid
adhesive with the dry beads at the required ratios. In any case,
the end result of applicant's construction methods is that adjacent
beads within a given body of the padding material will remain in
substantially fixed positions relative to each other after the
adhesive coating materials on the beads bond with each other.
Consequently, the pads of the present invention will be highly
breathable, impact resistant and will not bottom out under the
influence of repeated blows.
[0146] Representative Uses of Composite Materials Used As Padding
Materials
[0147] FIG. 22 represents some representative uses of the padding
materials of the present invention wherein said padding materials
are especially, adapted for use in various items of football gear.
Other sports gear or sports gear components can of course be made
from the hereindisclosed padding materials. Such materials also are
well suited for use in medical equipment such as prosthetic
devices, wheelchair cushions, mattresses and the like. And as
previously noted, the qualities of light weight, impact resistance
(and breathability) make these materials well suited as padding in
certain, non-human body-related/usages such as padding for
construction purposes (e.g., padding materials for building
foundations, under floors, between walls, padding for mechanical
equipment, packaging for perishable goods (e.g., eggs, fruit, etc.)
and air (or other gas) filter materials. Be that as it may, the
football gear shown in FIG. 22 includes a liner jersey 28 with
upper arm 30, rib 32, and sternum 34 pads. Such gear also can
include liner pants 36 with thigh 38 and knee 40 pads as well as a
helmet 42 with head pads 44 and 44'. Liner gear such as jersey 28
and pants 36 can be worn by a football player right next to the
body. External gear such as full shoulder pads and exterior or
playing jerseys and pants can be worn over such liner gear. Such
exterior gear also can be similarly padded with materials made
according to the teachings of the present invention. It should of
course be appreciated that applicant's padding materials can be
easily adapted for use in many other types of sports padding
devices including separate and removable pads such as the elbow 46
and forearm 48 pads depicted in FIG. 22.
[0148] FIG. 23 is a cut-away view of the elbow pad 46 of FIG. 22
employing padding material made according to the teachings of this
invention wherein a coated bead 52/void space 54 material is placed
in an outer casing 56. The outer casing 56 is preferably made of a
cloth-like or net-like material that is porous and breathable
(e.g., plastic mesh or net of a substantially waterproof material
such as polypropylene). In use, the entire pad 46 can be received
or sewn into a pocket 50 formed by portions 58 and 60 of the jersey
28 depicted in FIG. 22.
[0149] FIG. 24 shows a padding material 62 made according to the
teachings of this patent disclosure placed in two distinct casing
sections 64 and 64'. These casing sections 64 and 64' are each
associated with an outward facing, hard plastic cover 66 that is
connected to the casing sections 64 and 64' by means of
rivet-shaped connectors 68. Such a system could be used as a thigh
pad, rib pad and the like.
[0150] Bead Construction Materials
[0151] The beads of this invention can be made of various materials
e.g., plastics, ceramics (including glass), metal oxides, phenol
based resins, etc. For example, in the "plastics" group, expanded
ethylene, polystyrene and polypropylene are preferred bead
construction materials for both elastic and inelastic bead
materials. Ceramic, glass and metal oxide are somewhat preferred
construction materials for the inelastic beads of this patent
disclosure. One method for producing ceramic beads is described in
U.S. Pat. No. 4,239,519 ("the '519 patent"). For example, the '519
patent teaches how gels containing 5 to 6% solids will form
ceramic-forming droplets that consistently have a spherical shape.
Beads made from ceramic materials may, however, also be somewhat
resistant to those treatments (etching, corona treatments, etc.)
that often effect better bead/adhesive bonding in other bead
construction materials such as the previously noted plastics.
[0152] Plastics and resins are preferred for making elastic and/or
hollow beads that can be used in applicant's padding materials.
Such plastics are generally made from resins through the
application of heat, pressure, or both. Such resin materials
generally fall into two broad categories: (1) thermoplastic resins,
which can be heated and softened innumerable times without
suffering any basic alteration in characteristics; and (2)
thermosetting resins, which, once set at a temperature critical to
a given material, cannot be resoftened and reworked. Thermoplastic
resins and thermosetting resins have the advantage of readily
accepting corona, flame, plasma jet and etching treatments.
[0153] The principal kinds of thermoplastic resins that can be used
to make the beads of this invention include: (1)
acrylonitrile-butadiene-sty-rene resins; (2) acetals; (3) acrylics;
(4) cellulosics; (5) chlorinated polyethers; (6) fluorocarbons,
polytetrafluoroethylene; polychlorotrifluoroethylene, and
fluorinated ethylene propylene; (7) nylons (polyamides); (8)
polycarbonates; (9) polyethylenes (including copolymers); (10)
polypropylenes (including copolymers such as ethyl propylene
copolymers ("epps")); (11) polystyrenes; and (12) vinyls (polyvinyl
chloride). The principal kinds of thermosetting resins that can be
employed to make the inelastic beads suitable for the practice of
this invention include: (1) alkyds; (2) allylics; (3) the aminos
(melamine and urea); (4) epoxies; (5) phenolics; (6) polyesters;
(7) silicones; and (8) urethanes.
[0154] As previously noted in this patent disclosure, applicant has
defined "inelastic" beads as those that will not recover to their
original shape after an impact or extended compression. By use of
the term "inelastic", applicant means that a bead material has what
is commonly referred to as poor "memory". Hence, after deformation,
such materials will not return to their original shape and will not
retain much of their original impact attenuation properties. In
effect, many individual beads in such a system are permanently
crushed. It might be noted in passing here that applicant's test
for material elasticity was to place a 0.5 inch piece of a subject
foam under a device which compressed the foam at ambient conditions
to 50 percent of its original thickness. The pressure was then
released. By way of example only, after 30,000 compression cycles
of this test, applicant noted only a 10 to 15 percent reduction in
thickness in certain elastic polyethylene foams and a 20 to 25
percent reduction in thickness for certain elastic polypropylene
foams. Similarly tested inelastic foams however remained
substantially at their compressed thicknesses indefinitely.
Adhesive Materials
[0155] The adhesives that can be employed in the practice of this
invention are generally characterized by the fact that they (1) can
be placed in solution or suspension (colloidal or otherwise) in
liquid (or semi-liquid) carrier fluids (polar, non-polar, organic,
inorganic) known to this art and (2) will cure to hardness levels
of Shore A 20 to shore A 95. The carrier fluids used to convey such
adhesive materials should be capable of acting as a carrier for a
particular adhesive material components of applicant's adhesive
compositions as well as being capable of wetting the surface of the
bead material being employed to make a given padding material.
Beyond that, the adhesive components of applicant's
carrier/adhesive systems may be broadly classified into two main
groups; organic and inorganic. The organic adhesives can be
subdivided into those of animal origin, vegetable origin, and
synthetic origin. Other useful classifications for those adhesives
that can be used to make the hereindescribed padding materials are
based upon the chemical nature of the adhesive. Such chemical
classifications usually comprise (1) protein or protein
derivatives, (2) starch, cellulose, or gums and their derivatives,
(3) thermoplastic synthetic resins, (4) thermosetting synthetic
resins, (5) natural resins and bitumens, (6) natural and synthetic
rubbers, and (7) inorganic adhesives.
[0156] Two part thermoplastic or thermosetting adhesive systems are
somewhat preferred for the practice of this invention. They usually
consist of a resin and a hardener. The resin typically has a polyol
or bulk polymer component. The hardener causes this polymer to link
up, chain extend, harden and/or cure. Those skilled in this art
will appreciate that the term "resin" typically refers to the base
stock used in an adhesive. With less preferred, but still operable,
single component adhesives, the resin will have most, but not all,
of the bonding power of the final product.
[0157] Thermoplastic synthetic resin adhesives comprised of a
variety of polymerized materials such as polyvinyl acetate,
polyvinyl butyral, polyvinyl alcohol, and other polyvinyl resins;
polystyrene resins; acrylic and methacrylic acid ester resins;
cyanoacrylates; and various other synthetic resins such as
polyisobutylene, polyamides, coumarone-indene products, and
silicones also can be employed in the practice of this invention.
Other thermosetting synthetic resin adhesives that can be used in
the practice of this invention will include phenol-aldehyde,
urea-aldehyde, melamine-aldehyde, as well as certain
condensation-polymerization materials such as furane and
polyurethane resins. Adhesive compositions containing phenol-,
resorcinol-, urea-, melamine-formaldehyde, phenolfurfuraldehyde,
and the like also can be used in the practice of this
invention.
[0158] The adhesive containing compositions of this patent
disclosure also may contain such additives as tackifiers, viscosity
modifiers, anti-oxidants, UV inhibitors, UV stabilizers, catalysts,
heat stabilizers, oxygen scavengers, colorants, biocides, odorants,
etc. It might also be noted in passing that applicant has found
that Dibutyl Tin Dilaureate (a general purpose organo-tin catalyst)
used at 0.075% loading (a 1:1333 catalyst to adhesive ratio), can
serve as a particularly good adhesive curing catalyst. In all such
variations, however, the cured form of the adhesives should have
Shore A values ranging from about 20 to about 95. Adhesives having
hardness levels (in their cured state) ranging from about Shore A
50 to a Shore A value of about 90 are even more preferred in the
practice of this invention when used in conjunction with inelastic
thermosetting or high temperature thermoplastic bead materials.
Those cured adhesives having hardnesses levels ranging from about a
Shore A 60 to about Shore A 85 are even more preferred for use with
such beads.
[0159] Some of the more preferred, commercially available,
adhesives that can be used in the practice of this invention, and
their relative attributes, are as follows:
TABLE-US-00003 Adhesive Qualitative properties Rubinate 9272 .RTM.
Low hardness, low strength, high flexibility, high elongation,
moisture curing polyurethane. Especially good for soft bead
products. Rubinate 9234 .RTM. High hardness, high strength,
brittle, moisture curing polyurethane. Especially good for hard
bead products. Rubinate 9457 .RTM. Medium high hardness, medium
high strength, fair flexibility and elongation. Good for medium
hard bead or hard bead products requiring some flexibility.
[0160] Experimental Findings Re: Impact Tests
[0161] Applicant's experimental findings have established that,
when used in the hereindescribed proportions (20-80 wt. %, or 1-5
vol. %), certain adhesives (those having hardness levels ranging
from about Shore A 20 to Shore A 95) play an important part in the
ability of the hereindisclosed bead/adhesive/void space padding
materials to repeatedly absorb high levels of impact energy. This
finding was primarily established through use of various impact
tests. For example, in one series of such impact tests (so-called
Acceleration Peak (G) tests) whose results are shown below as Test
1 below, applicant kept the percent of adhesive constant at 2
volume percent and varied the "hardness" of the adhesive. This
variation in hardness was accomplished by increasing the number of
chemically active sites of the adhesives by adding varying amounts
of a second chemically active component to a base resin system. For
example in polyurethane formulations, the relative amount of a
N.dbd.C.dbd.O component of the adhesive was varied relative to a
NH--C--NH component of said adhesive. Such tests indicated that as
the hardness of the adhesive material used to create the subject
bead/adhesive/void space materials of this patent disclosure was
increased, the material's impact absorptive ability increased as
well. These tests also indicated that the adhesive itself (and not
just the beads) contributes greatly to the impact absorption
qualities of applicant's padding materials.
[0162] For example, line 1 of Test 1 shows that when the subject
padding material employs beads designated as bead type 3420
(spherical, high density, polypropylene beads) and uses 2% (by
vol.) of a "soft" adhesive designated as 9272, the Acceleration
Peak (G) value ("AP(G) value") is 107--for the first impact upon
that material. This 107 AP(G) value represents good impact
resistance for this material--on the first impact. The second
impact (see line 2 of Test 1), however, produced an AP(G) value of
272. This value indicates a substantial lessening or deterioration
in the impact resistance of the material whose attributes are given
in line 1. The third impact (line 3) produced an AP(G) value of
465. This value indicates that the padding material's impact
resistance greatly deteriorated under the three impacts to a level
(465) which is such that the material would not be considered an
acceptable padding for high impact sports gear.
[0163] Line 4 of Test 1 shows that when the padding material
employs the same bead (3420) and the same volume (2%) of a "harder"
adhesive (adhesive 9457), under otherwise comparable test
conditions, the AP(G) value for the first hit was 95. This 95 value
is qualitatively "better" than the 107 value for the padding
material described in line 1, i.e., the padding material of line 4
is a better padding material than the material described in line
1--under the first impact. The second impact upon the padding
material described in line 4 produced an AP(G) value of 182 (see
line 5 of Test 1). This 182 value is better than the 272 value
produced by the second hit on the material described in line 1.
Similarly, the third hit upon the material of line 4 produced a 266
AP(G) value which is much better than the 465 value for the third
hit upon the material of line 1. Thus, these tests show that the
harder adhesive (9457) produces better repeated blow impact
resistance in padding materials of this type relative to the softer
adhesive (9272).
[0164] Lines 8 and 9 of Test 1 show the results of a series of
tests comparable to those described above. The spherical bead
employed (bead 3419) was, however, considerably softer than the
bead employed (bead 3420) in the previous tests. A padding system
using this softer bead (3419) and the softer adhesive (9272) as
indicated in line 8 of Test 1 produced a first impact AP(G) value
of 493. By way of comparison, the padding system using the softer,
bead (3419) and the harder adhesive (9457) described in line 4 of
Test 1 produced a first impact value of 297. Thus, use of the
harder adhesive (9457) improved the impact resistance of a padding
material employing softer beads (3419).
[0165] Lines 10 and 11 of Test 1 show similar improved results from
use of the harder adhesive (9457) relative to the softer adhesive
(9272) in a system wherein the beads had a cylindrical
configuration rather than spherical configurations of the beads
used in all of the other tests described above. Thus, applicant has
concluded that the shape of the beads was not responsible for the
improved results obtained through use of harder adhesives such as
adhesive 9457.
[0166] Test 2 shows the results of another series of tests wherein
Acceleration Peak (G) values were determined for various padding
material wherein the effects of changes in the volume percentage of
a soft adhesive (9272) on the AP(G) values of the material were
studied. Test 2 also explores the effects of comparable changes in
the volume percentage of a hard adhesive (9457) on AP(G) values of
the resulting material. For example, line 1 of Test 2 describes a
padding material employing beads designated as 3420 (again,
spherical, hard beads made of polypropylene). Line 1 shows that use
of 2 volume percent of soft adhesive (9272) adhesive produced a
AP(G) value of 110. Impact number 2 on this same material produced
an AP(G) value of 254 (see line 2 of Test 2) and impact number 3
produced a 383 value (see line 3 of Test 2).
[0167] Line 4 of Test 2 describes a padding material comparable to
that described in line 1 except for the fact that the padding
material described in line 4 uses 3% of the soft adhesive (9272).
This material produced a first impact AP(G) value of 103, a second
impact value of 209 and a third impact value of 317. Each of these
three AP(G) values represent a modest gain over the comparable
values produced by the 2% soft adhesive systems described in lines
1 to 3 of Test 2.
[0168] The results of comparable impact tests on a padding material
employing 4% of the soft adhesive (9272) generally indicates that
the material has lost some of its impact resistance (see lines 7
and 8) relative to the first two impacts on both the 2% and 3% soft
adhesive systems. The third impact test on the 4% soft adhesive
system (see line 9) shows some improvement (342 v. 383) over the
third impact results of the 2% adhesive material. It also shows
some loss in impact resistance (342 v. 317) relative to the third
impact on the 3% soft adhesive containing padding material. The 5%
soft (9272) adhesive containing material described in lines 10 to
12 shows AP(G) values that are, in most cases, modest improvements
over the 2%, 3% and 4% adhesive materials.
[0169] The Test 2 results beginning at line 14 show the results of
impact tests comparable to those just described--except for the
fact that the line 14-35 tests employed a hard adhesive (9457)
rather than the soft adhesive (9272) previously described with
respect to the test described in lines 1-13 of Test 2. For example,
lines 14-16 of Test 2 show AP(G) values for the first three impacts
upon a hard bead (3420)/2% hard adhesive (9457) system to be 90,
177 and 252. Each of these AP(G) values is lower (and therefore
"better") than the comparable values produced by the 2% soft
adhesive (9272) system described in lines 1 to 3 of Test 2. Lines
18-20 of Test 2 show that the AP(G) values (i.e., 83, 151 and 220)
for the first three impacts on the 3% hard adhesive (9457) are
better than those for the 3% soft adhesive (i.e., 103, 209 and
317). Moreover, the fourth, fifth and sixth hits on the 3% hard
adhesive material suggest that the added impacts are having less
and less destructive effects. The 3% hard adhesive values for the
first three hits are also better than the comparable values for the
2% hard adhesive (i.e., 90, 177 and 252). The AP(G) values for
first three impacts on the 4% hard adhesive (i.e., 90, 136 and 161)
also are better than those for the 4% soft adhesive (i.e., 114, 264
and 342). The 4% hard adhesive (9457) values also are generally
better than the 2% and 3% hard adhesive systems. Moreover, the
fourth, fifth and sixth impacts produce AP(G) values (i.e., 197,
214, 228) that suggest that the bad effects of repeated blows is
reaching a plateau in the 4% hard adhesive system.
[0170] The first three AP(G) values for the 5% hard (9457) adhesive
(i.e., 92, 134 and 160) of Test 2 are much better than those for
the 5% soft adhesive (i.e., 105, 208 and 289). They are, however,
only marginally better than the results of the first three impacts
on the 4% hard adhesive material. The 5% hard adhesive system does,
however, produce better results (i.e., 182, 203 and 209 AP(G)
values) with respect to the fourth, fifth and sixth impacts. Thus,
it would appear that the impact resistance of these padding
materials is reaching a plateau when the adhesive constitutes about
5 value percent of the padding material. As was previously noted,
this 5 volume percent for the adhesive in the overall padding
material generally corresponds to about 80 weight percent of the
padding material owing to the fact that the adhesives are normally
much more dense than the beads. Moreover, applicant has generally
found that the use of more than about 5 volume percent adhesive (or
more than about 80 weight percent adhesive) tends to clog or fill
in the void volumes of applicant's padding materials to the point
where their desired breathing qualities are greatly impaired.
Again, applicant prefers that these padding materials have void
volumes of at least 10% of the volume of the material. Again,
applicant has found that when more than 5 volume percent (or 80
weight percent) adhesive is used, the void volume usually falls
below about 20 volume percent of the material. Hence, for reasons
of breathability, as well as diminishing returns with respect to
impact resistance, applicant prefers to use no more than 80 weight
percent (and preferably less than 60 weight percent) adhesive in
the padding materials of this patent disclosure.
TABLE-US-00004 TEST 1 Accel Vol. Test Size Melt Drop Peak Bead %
adhesive Temp (thickness) Point Ht. (G) 1 3420 2% 9272 122 deg. F.
1'' 275 deg. F. .86 m 107 2 272 3 465 4 3420 2% 9457 122 deg. F.
1'' 275 deg. F. .86 m 95 5 182 6 266 7 379 8 3419 2% 9272 122 deg.
F. 1'' 275 deg. F. .86 m 493 9 3419 2% 9457 122 deg. F. 1'' 275
deg. F. .86 m 297 10 Cylindrical 2% 9272 122 deg. F. 1'' 329 deg.
F. .86 m 327 11 Cylindrical 2% 9457 122 deg. F. 1'' 329 deg. F. .86
m 146 12 486
TABLE-US-00005 TEST 2 BEAD UT CODE SAMPLE DROP ACCELERATION BEAD
BEAD DENSITY % (HELMET THICK- IMPACT HEIGHT PEAK CODE MATERIAL
(pcf) adhesive #) NESS CONDITION LOCATION ANVIL (M) (G) 1 3420 epp
3.5 2% 9272 BR0301 1'' hot OT flat 0.86 110 2 3420 epp 3.5 2% 9272
BR0301 1'' hot OT flat 0.86 254 3 3420 epp 3.5 2% 9272 BR0301 1''
hot OT flat 0.86 383 4 3420 epp 3.5 3% 9272 BR0302 1'' hot OT flat
0.86 103 5 3420 epp 3.5 3% 9272 BR0302 1'' hot OT flat 0.86 209 6
3420 epp 3.5 3% 9272 BR0302 1'' hot OT flat 0.86 317 7 3420 epp 3.5
4% 9272 BR0303 1'' hot OT flat 0.86 114 8 3420 epp 3.5 4% 9272
BR0303 1'' hot OT flat 0.86 264 9 3420 epp 3.5 4% 9272 BR0303 1''
hot OT flat 0.86 342 10 3420 epp 3.5 5% 9272 BR0304 1'' hot OT flat
0.86 105 11 3420 epp 3.5 5% 9272 BR0304 1'' hot OT flat 0.86 208 12
3420 epp 3.5 5% 9272 BR0304 1'' hot OT flat 0.86 289 13 3420 epp
3.5 5% 9272 BR0304 1'' hot OT flat 0.86 379 14 3420 epp 3.5 2% 9457
BR0305 1'' hot OT flat 0.86 90 15 3420 epp 3.5 2% 9457 BR0305 1''
hot OT flat 0.86 177 16 3420 epp 3.5 2% 9457 BR0305 1'' hot OT flat
0.86 252 17 3420 epp 3.5 2% 9457 BR0305 1'' hot OT flat 0.86 357 18
3420 epp 3.5 3% 9457 BR0306 1'' hot OT flat 0.86 83 19 3420 epp 3.5
3% 9457 BR0306 1'' hot OT flat 0.86 151 20 3420 epp 3.5 3% 9457
BR0306 1'' hot OT flat 0.86 220 21 3420 epp 3.5 3% 9457 BR0306 1''
hot OT flat 0.86 229 22 3420 epp 3.5 3% 9457 BR0306 1'' hot OT flat
0.86 277 23 3420 epp 3.5 3% 9457 BR0306 1'' hot OT flat 0.86 278 24
3420 epp 3.5 4% 9457 BR0307 1'' hot OT flat 0.86 90 25 3420 epp 3.5
4% 9457 BR0307 1'' hot OT flat 0.86 136 26 3420 epp 3.5 4% 9457
BR0307 1'' hot OT flat 0.86 161 27 3420 epp 3.5 4% 9457 BR0307 1''
hot OT flat 0.86 197 28 3420 epp 3.5 4% 9457 BR0307 1'' hot OT flat
0.86 214 29 3420 epp 3.5 4% 9457 BR0307 1'' hot OT flat 0.86 228 30
3420 epp 3.5 5% 9457 BR0308 1'' hot OT flat 0.86 92 31 3420 epp 3.5
5% 9457 BR0308 1'' hot OT flat 0.86 134 32 3420 epp 3.5 5% 9457
BR0308 1'' hot OT flat 0.86 160 33 3420 epp 3.5 5% 9457 BR0308 1''
hot OT flat 0.86 182 34 3420 epp 3.5 5% 9457 BR0308 1'' hot OT flat
0.86 203 35 3420 epp 3.5 5% 9457 BR0308 1'' hot OT flat 0.86
209
[0171] It is counterintuitive that a harder, and presumably more
brittle, adhesive material would be a better impact absorbing
material than a softer, more elastic adhesive. Nonetheless, this is
the case in applicant's bead/adhesive/void space padding materials.
Applicant has made many tests such as Tests 1 and 2 and have
concluded that some form of micro-fracturing of the adhesive, and
perhaps even certain kinds of beads, takes place during impact and
that this micro-fracturing can greatly contribute toward the impact
absorbing quality of these padding materials.
[0172] While applicant's invention has been described with respect
to various theories, specific examples, and a spirit that is
committed to the concept of coating certain sized beads with a
layer of hard adhesive in order to produce padding materials having
improved breathability and impact resistance, it is to be
understood that this invention is not limited thereto, but rather
only should be limited by the scope of the following claims.
* * * * *