U.S. patent application number 14/174111 was filed with the patent office on 2014-06-05 for foam-like materials and methods for producing same.
This patent application is currently assigned to ALLERGAN, INC.. The applicant listed for this patent is ALLERGAN, INC.. Invention is credited to Miriam M. Abiad, Alexei Goraltchouk, Kevin Ma, Nicholas J. Manesis, Jordan Thompson, Dennis Van Epps.
Application Number | 20140154491 14/174111 |
Document ID | / |
Family ID | 44123415 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140154491 |
Kind Code |
A1 |
Goraltchouk; Alexei ; et
al. |
June 5, 2014 |
FOAM-LIKE MATERIALS AND METHODS FOR PRODUCING SAME
Abstract
Described herein are foam-like materials having substantially
the same physical structure of polyurethane foams but with
properties that can be tailored for a particular application.
Methods of forming these foam-like materials are also
described.
Inventors: |
Goraltchouk; Alexei;
(Rensselaer, NY) ; Thompson; Jordan; (Chino Hills,
CA) ; Abiad; Miriam M.; (Costa Mesa, CA) ; Ma;
Kevin; (Scotts Valley, CA) ; Van Epps; Dennis;
(Goleta, CA) ; Manesis; Nicholas J.; (Escondido,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALLERGAN, INC. |
Irvine |
CA |
US |
|
|
Assignee: |
ALLERGAN, INC.
Irvine
CA
|
Family ID: |
44123415 |
Appl. No.: |
14/174111 |
Filed: |
February 6, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13093505 |
Apr 25, 2011 |
8679570 |
|
|
14174111 |
|
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|
61328358 |
Apr 27, 2010 |
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61329518 |
Apr 29, 2010 |
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Current U.S.
Class: |
428/220 ; 264/49;
521/62 |
Current CPC
Class: |
C08J 9/26 20130101; C08J
9/365 20130101; C08J 2201/046 20130101 |
Class at
Publication: |
428/220 ; 521/62;
264/49 |
International
Class: |
C08J 9/26 20060101
C08J009/26 |
Claims
1. A porous material made by the steps of: providing a polyurethane
foam base material having a porous surface; contacting the base
material with a first fluid material; drawing the first fluid
material into intimate contact with the base material to form a
coat of the first fluid material on the base material; curing the
coat on the base material; and removing the base material from the
cured coat, resulting in a porous material comprising the cured
first fluid material.
2. The porous material of claim 1 wherein the step of drawing the
first fluid material into intimate contact with the base material
includes using a vacuum.
3. The porous material of claim 2 further comprising using positive
air pressure to blow away excess fluid material from the base
material before the step of curing.
4. The porous material of claim 1 wherein the first fluid material
is a silicone elastomer dispersion.
5. The porous material of claim 1, wherein the base material is
removed by dissolution.
6. The porous material of claim 1 wherein the step of removing the
base material comprises removing all of the base material from the
cured first fluid material.
7. The porous material of claim 1 wherein the step of removing the
base material comprises contacting the base material with a
solution, mixture, suspension, emulsion, dispersion or combination
thereof capable of dissolving the base material.
8. The porous material of claim 1 wherein the step of removing the
base material comprises degradation or dissolution of the base
material with a base, a solvent, an enzyme, an acid, heat,
oxidation, ultraviolet light, gamma irradiation, visible light,
infrared light or a combination thereof.
9. The porous material of claim 1 wherein the coat has a thickness
of about 10 .mu.m to about 500 .mu.m.
10. The porous material of claim 1 wherein the coat has a thickness
of about 50 .mu.m to about 100 .mu.m.
11. The porous material of claim 1 further comprising repeating the
contacting step to achieve a desired thickness of the coat.
12. A porous material made by the steps of: providing an open cell
polyurethane foam base material having a porous surface; contacting
the base material with a liquid silicone dispersion to form a
coating on the base material; removing a portion of the liquid
silicone dispersion from the base material by using a vacuum to
draw the first fluid material into intimate contact with the porous
surface of the base material and using positive air pressure to
blow away excess fluid material; curing the liquid silicone
dispersion remaining on the base material after the step of
removing a portion, to form a cured silicone elastomer coating on
the base material; and removing the base material from the silicone
elastomer coating, thereby leaving a porous material comprising
silicone.
13. The porous material of claim 12 further comprising using
positive air pressure or a vacuum to remove excess fluid material
from the base material before the step of curing.
14. The porous material of claim 12 wherein the step of removing
the base material comprises contacting the base material with a
solution capable of dissolving the base material.
15. The porous material of claim 12 wherein the step of removing
the base material comprises degradation or dissolution of the base
material with a base, a solvent, an enzyme, an acid, heat,
oxidation, ultraviolet light, gamma irradiation, visible light,
infrared light or a combination thereof.
16. The porous material of claim 12 wherein the coating has a
thickness of about 10 .mu.m to about 500 .mu.m.
17. The porous material of claim 12 wherein the coating has a
thickness of about 50 .mu.m to about 100 .mu.m.
18. The porous material of claim 1 further comprising repeating the
contacting step to achieve a desired thickness of the coating.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/093,505, filed Apr. 25, 2011, which claims
the benefit of and priority to U.S. Provisional Patent Application
No. 61/328,358, filed on Apr. 27, 2010 and 61/329,518, filed on
Apr. 29, 2010, the entire disclosure of each of these applications
being incorporated herein by this reference.
[0002] The present invention generally relates to foam-like
materials suitable for various industrial and general purpose
applications.
BACKGROUND
[0003] General purpose foams have conventionally been manufactured
from polyurethane. Polyurethane foams are widely used in industrial
applications and everyday life. The porous geometry of polyurethane
foams makes them ideal candidates as the geometry result in both
strong and flexible material. Example uses include high resiliency
flexible foam seating, rigid foam insulation panels, microcellular
foam seals, and carpet underlay.
[0004] However, foams made substantially of polyurethane generally
have very low acid and base resistance, swell readily in a large
range of solvents (N-methylpyrrolidone, dimethyl sulfoxide, ethyl
acetate, methyl ethyl ketone, dichloromethane, and swell somewhat
in an even broader range of solvents (xylene, hexane, dioxane,
acetone) depending on its formulation. Additionally, polyurethane
foams generally have a low resistance to oxidation and ultraviolet
light (UV), are not degradable in a controlled manner, and are not
readily made environmentally friendly (quickly break down into
unsafe components).
[0005] Such properties make them less than ideal for many general
purpose applications for which substantially opposite properties
are desired. All of these properties have an impact on performance
range, for example use in filtration with solvents, use in
filtration with acids and bases, use in insulation with solvents,
acids, and bases, use in oxidative environments, use in
environments with metal salts, use in environments with high UV or
radiation exposure, hydrolytic degradation in cushioning, and the
like.
[0006] As such, there is a need in the art for general purpose
foams with the broad applications of commonly used porous
polyurethane foam materials but without the drawbacks described
above.
[0007] U.S. patent application Ser. No. 13/015,309, filed on Jan.
27, 2011 discloses novel methods for making materials suitable for
implantation in a mammal, the methods including the steps of
providing a base material having a desirable surface topography,
such as a polyurethane foam, contacting the base member with a
silicone-based fluid material to form a coating, and allowing the
coating to set to form a silicone-based structure suitable for
implantation in a mammal. The entire disclosure of this application
is incorporated herein in its entirety by this specific
reference.
[0008] The present invention provides novel foam-like materials and
methods of making the same.
SUMMARY
[0009] Described herein are methods of making foam-like materials
having one or more physical characteristics, such as topography,
porosity, shape, substantially identical to conventional foam
materials, for example, substantially identical to a polyurethane
foam. The present foam like materials are made from and comprise
materials that are different from conventional foams, and with
properties that can be tailored for particular applications. The
foam-like materials described herein can have useful properties
such as making them suitable as or in filtration systems, as or in
insulation, as a composite member in an oxidative environment, as a
composite member in an environment with a high UV or radiation
flux, as a hydrolytic degradation means in cushioning, and the
like.
[0010] Also described herein are methods of making foam-like
materials having at least one property described above. The first
step in the method is providing a base material having a porous
surface. Then, the base material is contacted with a first fluid
material in a manner causing the first fluid material to enter the
porous surface. As an optional step, at least a portion of the
first fluid material is removed resulting in a desired porosity.
The first fluid material is then cured within the porous surface of
the base material forming a cured first fluid material with the
desired porosity. At least a portion of the base material is then
removed thereby leaving a foam-like material comprising the cured
first fluid material having a textured surface substantially
identically conforming to the surface of the base material.
[0011] Also disclosed are materials and compositions made by the
steps described herein.
[0012] In some embodiments, the removing step is accomplished using
a vacuum to draw the fluid into the porous surface, using
pressurized air, using an airknife to blow away excess fluid
material, pressing the base material to squeeze out excess fluid
material or a combination of those procedures.
[0013] The base materials described herein have properties which
depend on the desired resultant foam-like material properties. In
one embodiment, the base material has a thickness between about 10
.mu.m and about 3 mm. In other embodiments, the base material has a
thickness of up to about 3 m.
[0014] The base material can also be made of a material which is
removable from the cured first fluid material without substantially
causing a change in the microstructure and/or macrostructure
thereof. In other embodiments, the base material is a foam made
from at least one material selected from the group consisting of
polyethylene, polyethylene vinyl acetate, polystyrene, polyvinyl
alcohol, Styrofoam, a polyolefin, polyester, polyether,
polysaccharide, polyamide, polyacrylate, a material which contains
aromatic or aliphatic structures in the backbone, as
functionalities, cross-linkers or pendant groups, a copolymer
thereof, a terpolymer thereof, a quarternaly polymer thereof, a
metal, a metal foam, a ceramic, a ceramic foam, and combinations
thereof. In one embodiment, the base material is removed by
dissolution, degradation or a combination thereof.
[0015] In another embodiment, the fluid material is a homogenous
liquid, dispersion, solution, emulsion, or a combination thereof.
The fluid material is contacted to the base material in such a
manner as to deposit a conformal coat unto the porous surface which
can have a thickness of about 1 .mu.m to about 3000 .mu.m.
[0016] The foam-like materials described herein generally can be
substantially non-degradable. In example embodiments, the foam-like
materials are non-degradable under at least one condition selected
from radiation, UV light, in an environment with metal slats, basic
conditions, acidic conditions or a combination thereof.
[0017] In some embodiments, the contacting step coats the base
material with the first fluid material and can fill about 0.001% to
about 100% of the voids in the base material with the first fluid
material.
[0018] In still other embodiments, the removing step removes about
5% to about 100% of the base material from the cured first fluid
material. In another embodiment, the removing step removes
substantially all of the base material from the cured first fluid
material. The removing step can be repeated one or more times.
Further, in one embodiment, the removing step comprises contacting
the base material with a solution, mixture suspension, emulsion,
dispersion or combination thereof capable of dissolving the base
material and/or comprises degradation or dissolution of the base
material with a base, a solvent, an enzyme, an acid, heat,
oxidation, ultraviolet light, gamma irradiation, visible light,
infrared light or a combination thereof.
[0019] In another embodiment, the method further comprises at least
a second contacting step wherein the foam-like material is
contacted with at least one additional fluid material wherein the
at least one additional fluid material coats the foam-like
material. The method can further comprise at least a second curing
step wherein at least one additional fluid material is allowed to
cure on the foam-like material thereby forming a processed
foam-like material. In other embodiments the at least one
additional fluid material and the first fluid material are the same
or are different.
[0020] In still another embodiment, the second contacting step
allows the second fluid material to fill areas wherein the base
material had been removed. The second contacting step can allow the
second fluid material to about 0.001% to about 100% of the area
wherein the base material has been removed.
[0021] The second fluid material, in one embodiment, is selected
from the group consisting of a polyolefin, a polyester, a
polyether, a polycarbonate, a polyamide, a polyamine, a
polyacrylate, a halogenated polymer, a metal, copolymers thereof
and blends thereof.
[0022] In some embodiments, the method further comprises the step
of curing the at least one additional fluid material and removing
the foam-like material resulting in a post processed foam-like
material. In another embodiment, about 5% to about 100% of the
foam-like material is removed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is an SEM micrograph of a implantable material made
in accordance with a method of the invention; and.
[0024] FIG. 2 is an SEM micrograph of a melamine foam which can be
used as a base member in accordance with a method of the
invention.
[0025] FIGS. 3-9 are images of other materials that can be useful
as base materials in accordance with different embodiments of the
invention.
[0026] FIG. 10 illustrates an exemplary general method scheme.
[0027] FIG. 11 A illustrates a cross-sectional SEM image of a base
material strut as described herein. FIGS. 11 B-D illustrate SEM
images two coatings, four coatings and six coatings of a fluid
material respectively on a base material strut.
[0028] FIG. 12 A illustrates an SEM image of a base material as
described herein. FIGS. 12 B-D illustrate SEM images of two
coatings, four coatings and six coatings of a fluid material
respectively on a base material.
[0029] FIG. 13 A illustrates an SEM image of a foam-like material
as described herein with the base material removed. FIGS. 13 B-E
illustrate SEM images of one coating, two coatings, three coatings
and four coatings of a fluid material respectively on the foam-like
material.
DETAILED DESCRIPTION
[0030] Described herein generally are foam-like materials useful
for industrial applications as well as having everyday
applicability. The foam-like materials have substantially the same
physical structure of polyurethane foams but with properties that
can be tailored for a particular application whether it be
industrial, medical, recreational, or the like. In other words,
materials other than polyurethane, or in addition to polyurethane,
can be used to form foam-like materials having a substantially
similar structure to polyurethane foams but with the properties of
the materials used. Methods of forming these foam-like materials
are also described.
[0031] The foam-like materials can have a reticulated structure
similar to one that can be made out of a polyurethane, which is
highly controllable anywhere from 5 PPI to 500 PPI with an open
cell structure. The foam-like structures described herein can be
further controllable from about 1 PPI to about 1000 PPI.
[0032] The foam-like materials may be used as coverings or outer
layers for virtually any application or article of manufacture.
Applications can range from solvent filtration systems to
cushioning in outdoor furniture with high exposure to sunlight.
[0033] The foam-like materials can be substantially inert and/or
substantially non-degradable, even under radiation, UV light, in an
environment with metal slats, acidic or basic conditions, oxidative
conditions, combinations thereof and the like. The foam like
materials have structures, for example, a microstructure, similar
or substantially identical to that of a base material from which it
is molded. The base material may be, or may not be, a degradable
material and preferably has at least a porous surface.
[0034] For example, a method for making a foam-like material in
accordance with one embodiment comprises the steps of providing a
base material including a porous surface, generally defined by
interconnected pores, and contacting the base material with a first
fluid material in a manner causing the first fluid material to
enter the porous surface. At that point, a vacuum or other means
may be applied to the base material in order to facilitate the
contacting step. Excess first fluid material may be removed from
the base material to obtain a coating of the first fluid material
on and through the porous surface with a desired porosity.
[0035] In some embodiments, the first fluid material is contacted
to the base material in such a manner as to deposit a conformal
coat unto the porous surface of the base material. The conformal
coating can have a thickness of about 1 .mu.m to about 3000 .mu.m,
about 10 .mu.m to about 500 .mu.m or about 50 .mu.m to about 100
.mu.m. The fluid materials, in some embodiments, substantially fill
or completely fill the porous surface of the base material. In
other embodiments, the void space in the porous base material
surface is filled to about 0.001% to about 100%, about 0.01% to
about 75%, or about 0.1% to about 50% and about +/-0.7% to about
60% by standard deviation.
[0036] The first fluid material is then allowed to cure, forming a
cured first fluid material coated on and within the porous surface
of the base material having the desired porosity. The contacting
step may be repeated once, twice, three or more times, for example,
up to 1000 times, until a desired thickness and/or final density is
achieved.
[0037] The first fluid material can be coated on the base material
thereby substantially conforming to the structure of the base
material. Also, the first fluid material can be contacted with the
base material in such a manner that the first fluid material
substantially fills the void space of the base material's porous
surface, thereby assuming a textured surface substantially opposite
the base material. Either method is within the scope of the present
disclosure.
[0038] The underlying base material may then be removed from the
cured first fluid material. For example, the base material is
contacted with a solution, mixture, suspension, emulsion,
dispersion or combination thereof containing a dissolvent or a
degradant. Other removal methods include degradation by a base or
an acid, application of heat, application of at least one form of
energy such as ultraviolet light, gamma rays or irradiation,
visible light or infrared light, application of an appropriate
solvent, application of an enzyme for enzymatic degradation and
combinations thereof. The base material can be removed by
dissolution, degradation or both. Once the base material is
removed, the resulting foam-like material is flexible and includes
a porous surface substantially identically conforming to the porous
surface and/or interconnected spheres of the base material.
[0039] The removal can eliminate substantially all of the base
material or a portion thereof. For example, in some embodiments,
about 5% to about 100% of the base material is removed. In other
embodiments, about 50%, about 60%, about 70%, about 80%, about 90%
or more of the base material is removed. The base material can be
removed in more than one step. For example, about 50% of the base
material can be removed in a first step and about 50% in a second
removal step. Or, about 50% in the first step, about 30% in the
second step and about 20% in the third step. The number of steps
involved and the amount of base material ultimately removed is
dependent on, for example, the ultimate utility of the foam-like
material, the base material used, the fluid materials used and the
processing specifications (e.g., temperature, pressure, etc).
[0040] In some embodiments, the base material need not be removed.
Rather, the first fluid material, and any additional fluid
materials, is cured onto the porous base material and the base
material can serve as support for the foam-like materials described
herein. In other embodiments, the base material may aid in
providing a desired property for the foam-like material.
[0041] Following removal of the base material, the foam-like
material may be optionally further coated with a second fluid
material. The second fluid material may be the same as or different
than the first fluid material. The second fluid material is applied
to the foam-like material can be assisted by a vacuum and may be
repeated once, twice, three or more times, for example, up to 1000
times, until a desired thickness and/or final density is
achieved.
[0042] In some embodiments, coating with a second fluid material
serves to fill the voids in the foam-like material wherein the base
material was removed. Further, the second fluid material can fill
any other cracks or voids in the foam-like material making it
stronger. By further coating the foam-like material with a second
fluid material, a processed foam-like material is formed.
[0043] In some embodiments, the second fluid like material, much
like the first fluid material, is contacted in such a manner as to
deposit a conformal coat. The conformal coating can have a
thickness of about 1 .mu.m to about 3000 .mu.m, about 10 .mu.m to
about 500 .mu.m or about 50 .mu.m to about 100 .mu.m. The second
fluid material, in some embodiments, substantially fills or
completely fills voids within the cured first fluid material. The
void space within the cured first fluid material is filled to about
0.001% to about 100%, about 0.01% to about 75%, or about 0.1% to
about 50% and about +/-0.7% to about 60% by standard deviation.
[0044] Optionally, the cured first fluid material can be removed
post curing of the second fluid material. The removal can be of a
similar method to removing the base material as described herein.
The removal can eliminate substantially all of the cured first
fluid material or a portion thereof. For example, in some
embodiments, about 5% to about 100% of the cured first fluid
material is removed. In other embodiments, about 50%, about 60%,
about 70%, about 80%, about 90% or more of the cured first fluid
material is removed. The cured first fluid material can be removed
in more than one step. For example, about 50% of the cured first
fluid material can be removed in a first step and about 50% in a
second removal step. Or, about 50% in the first step, about 30% in
the second step and about 20% in the third step. The number of
steps involved and the amount of cured first fluid material
ultimately removed is dependent on, for example, the desired
properties of the foam-like material, the base material used, other
fluid materials used and the processing specifications.
[0045] The base material as described herein can be any material
capable of being removed from the foam-like material upon
completion thereof without substantially degrading or interrupting
the structure of the foam-like material. Removal of the base
material should not substantially cause a change in the
microstructure and/or macrostructure of the newly curried
material.
[0046] The base material can be biodegradable, resorbable or both.
In other embodiments, the base material is not removed at all or is
not completely removed from the final foam-like structure.
[0047] In one example embodiment, the base material is
polyurethane. However, the base material may comprise any suitable
porous material having the desired porous surface structure. In a
specific embodiment, the implantable materials are substantially
entirely comprised of silicone yet have the topographical structure
of a polyurethane foam. For example, a material in accordance with
one embodiment is a flexible, soft, silicone-based foam having
substantially the same or substantially identical geometry and
tissue disorganization potential of a polyurethane foam, but with
the chemical inertness of a silicone. FIG. 1 is an SEM image of a
polyurethane foam strut 4 coated with silicone elastomer 6, in
accordance with an embodiment of the invention.
[0048] Alternative to polyurethane, the base material may comprise
melamine, for example, melamine foam. FIG. 2 is an SEM micrograph
of a melamine foam 8 having a topography defined by highly
interconnected, open pores. Other base member materials useful are
also contemplated and include, for example, foams made from
polyethylene, polyethylene vinyl acetate, polystyrene, polyvinyl
alcohol, Styrofoam, or generally a polyolefin, polyester,
polyether, polysaccharide, polyamide, polyacrylate, a material
which contains aromatic or aliphatic structures in the backbone, as
functionalities, cross-linkers or pendant groups, or a copolymer,
terpolymer or quarternaly polymer, thereof. Alternatively the
material may be a composite of one or more of the aforementioned
materials. In another embodiment of the invention the base material
can be a metal, for example a metal foam, a ceramic, or a composite
material.
[0049] It is to be appreciated that for a base material other than
polyurethane, said base material can be removed by a solvent or
other means, known to those of skill in the art, suitable for
removing the base material from the coating without substantially
altering or affecting the coating structure.
[0050] The base material itself has a thickness of at least about
10 .mu.m to about 3 millimeters. It is contemplated that the base
material may have a thickness of up to 3 meters. The thickness of
the base material can be selected based on factors including, for
example, the viscosity of the fluid material(s) used, the foam-like
material being produced, and manufacturing properties. For example,
if a foam-like material is being made as a coating for an
implantable medical device, base materials between about 10 .mu.m
and about 1 cm can be used. Alternatively, if for example seating
cushions are being created, the base materials can be from about 5
cm to about 3 m thick. A 3 m thick cushion material can be cut to a
desired size during manufacture and the thicker starting foam can
potentially save on manufacturing costs.
[0051] The base material can have varying pores sizes depending on
the application of the eventual foam-like materials to be generated
based on the interconnected pores of the base member. The base
materials described herein can have a pore size of about 100 .mu.m
to about 1000 .mu.m (RSD=0.01%-100%), or about 300 .mu.m to about
700 .mu.m (RSD=1%-40%). In one example embodiment, the pore size is
about 475 .mu.m.
[0052] The base materials can also have characteristic
interconnection sizes. The interconnection size can range from
about 30 .mu.m to about 700 .mu.m (RSD=0.01%-100%), or about 100
.mu.m to about 300 .mu.m (RSD=1%-40%). In one example embodiment,
the interconnection size is about 200 .mu.m. The number of
interconnections per pore is generally about 2 to about 20
(RSD=0.01.degree.)/0-50%), or about 3 to about 10 (RSD=1%-25%). In
one example embodiment, there are about 9 to 10 interconnections
per pore. Further, the base materials can have an average pore to
interconnection size ratio. In one embodiment, this ratio is about
3% to about 99%, or about 10% to about 99%. In one example
embodiment, the average pore to interconnection size ratio is about
44%.
[0053] Porous surfaces of base member materials useful in
accordance with various embodiments of the invention are shown in
FIGS. 3-9. More specifically, FIG. 3 is a SEM image of a
polyurethane foam base 10; FIG. 4 is an alumina aerogel foam 12;
FIG. 5 is another aerogel, for example, silica aerogel foam 14;
FIG. 6 is a silica foam 16; FIG. 7 is a HiP foam 18; FIG. 8 is a
magnesium ceramic foam 22; and FIG. 9 is another ceramic foam
24.
[0054] The fluid materials described herein can include polymers
that are relatively stable such as polyurethanes, silicones,
polyesters, polyolefins, polyisobutylene, ethylene-alphaolefin
copolymers, acrylic polymers and copolymers,
ethylene-co-vinylacetate, polybutylmethacrylate, vinyl halide
polymers and copolymers (e.g., polyvinyl chloride), polyvinyl
ethers (e.g., polyvinyl methyl ether), polyvinylidene halides
(e.g., polyvinylidene fluoride and polyvinylidene chloride),
polyacrylonitrile, polyvinyl ketones, polyvinyl aromatics (e.g.,
polystyrene), polyvinyl esters (e.g., polyvinyl acetate),
copolymers of vinyl monomers with each other and olefins (e.g.,
ethylene-methyl methacrylate copolymers, acrylonitrile-styrene
copolymers, ABS resins, and ethylene-vinyl acetate copolymers),
polyamides (e.g., Nylon 66 and polycaprolactam), alkyd resins,
polycarbonates, polyoxymethylenes, polyimides, polyethers, epoxy
resins, polyurethanes; rayon, rayon-triacetate, cellulose,
cellulose acetate, cellulose butyrate, cellulose acetate butyrate,
cellophane, cellulose nitrate, cellulose propionate, cellulose
ethers, carboxymethyl cellulose, and combinations thereof.
[0055] The fluid materials described herein can also include
polymers that are degradable, in some cases biodegradable or
bioerodable, such as, but not limited to poly(L-lactic acid),
polycaprolactone, poly(lactide-co-glycolide), poly(ethylene-vinyl
acetate), poly(hydroxybutyrate-co-valerate), polydioxanone,
polyorthoester, polyanhydride, poly(glycolic acid), poly(D,L-lactic
acid), poly(glycolic acid-co-trimethylene carbonate),
polyphosphoester, polyphosphoester urethane, poly(amino acids),
cyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate),
copoly(ether-esters) (e.g., PEO/PLA), polyalkylene oxalates,
polyphosphazenes and biomolecules such as fibrin, fibrinogen,
cellulose, starch, collagen, hyaluronic acid and combinations
thereof.
[0056] In one embodiment, the fluid materials cans each
independently be selected from a non-network, non cross-linked,
polyolefin, polyester, polyether, polycarbonate, polyamide,
polyamine, polyacrylate, a halogenated polymer (e.g., PTFE), and
the like, copolymer blends or other combinations thereof. Other
polymers include those with melting points and/or flowable polymers
(e.g., amorphous polymers can be flowable, but not exhibit a
melting point). In another embodiment, the fluid material may
comprise a dispersion, for example, a silicone dispersion. The
silicone dispersion may be a room temperature vulcanizing (RTV) or
a high temperature vulcanizing (HTV) silicone. In an exemplary
embodiment, the fluid material is a high temperature vulcanizing
(HTV) platinum-cured silicone dispersion in xylene or
chloroform.
[0057] Fluid materials can be in a form such as, but not limited to
solutions, emulsions, suspensions or combinations thereof. Also,
for example, any material that can be cured by crosslinking,
thermoplastics that set by change in temperature, material that set
by removal of solvents or any elastomer that cures or sets by any
known mechanism, can be used. It is further contemplated that
suitable metals can be used as fluid materials. For example,
aluminum, steel, silver, copper, and titanium are common metals
that can be foamed.
[0058] The type of fluid material forming applied on and into the
pores and/or interconnections of the base material, the total
dissolved solids of the fluid material, the method of removing the
excess fluid material, the carrier solvent, the method of applying
the fluid material, the temperature of materials, can be varied in
accordance with different embodiments of the present description to
achieve a foam-like material with a particular set of properties.
Other combinations can be easily envisioned by one skilled in the
art.
[0059] In some embodiments, the base material is coated with
multiple layers of different first fluid materials; up to and
exceeding 20 different fluid materials can be used. Different
composite materials can be formed with various mixtures of coating
layers. For example, a first fluid material may comprise a barrier
layer of a material capable of reducing or preventing diffusion of
chemical substances from the base material, and an additional first
fluid material applied on top of the first fluid material may
comprise a silicone-based material. Other first fluid materials may
be selected to achieve various characteristics of the final
product, such as materials to strengthen the foam-like material,
prevent chemical degradation, and/or change surface properties. In
other embodiments, the same fluid material can be used to coat a
base material up to and exceeding 20 times, or even 1,000
times.
[0060] In yet another embodiment, a method of making a material is
provided which generally comprises providing a base material
comprising a degradable foam and including a porous surface defined
by interconnected pores, and coating the base material with a
substantially non-degradable polymeric material, fluid material, to
obtain a substantially non-biodegradable polymeric structure. For
example, the base material may comprise a polyurethane foam. The
substantially non-degradable polymeric material can be selected
from a list of highly impermeable systems such as fluorinated
polyolefins to prevent diffusion of chemical entities which may
facilitate the degradation of polyurethane. Alternatively the
fluorinated polyolefin can be coated as a base layer, prior to the
final application of the silicone to act as a barrier layer.
[0061] In still another embodiment, the base material of a
preferred geometry, that is not dissolvable (e.g., a cross-linked
polymer having a porous surface) may be coated by a robust but
dissolvable material, such as, for example, a foam material
selected from the group of materials consisting of polystyrene,
polyethylene-co-vinyl acetate, and
poly(styrene-co-butadiene-co-styrene). The base material, e.g. the
non-dissolvable foam, can then be removed from the dissolvable
material coating, for example, degraded by relatively aggressive
means, for example, by acid digestion in 37% HCl, leaving the
robust but dissolvable material behind. A silicone-based fluid
material, for example, is deposited on the robust but dissolvable
foam, for example, using the methods described elsewhere herein.
The silicone-based fluid material may be in the form of a
dispersion having a solvent system that does not dissolve the
robust polymer. The silicone is allowed to set and/or cure, and the
robust material is then dissolved out by means which does not
affect the material of interest (e.g. silicone), for example, by
dissolution in acetone in the case of polystyrene. In this case,
the material of interest is not subjected to aggressive conditions
used to dissolve the original foam.
[0062] In one exemplary embodiment, the base material comprises a
material, for example, polyurethane or other suitable material,
having a pore size of 472+/-61 .mu.m (RSD=13%), interconnection
size: 206+/-60 .mu.m (RSD=29%), interconnections per pore:
9.6+/-1.8 (RSD=19%), Pore to interconnection size ratio of 44%.
[0063] An example embodiment, includes coating a polyurethane base
material with a fluoropolymer like PVDF at 20% wt. in HFIP, then
acid leaching the polyurethane followed by a DMSO wash to remove
excess, then coating with silicone some of which can be damaged by
the acid leaching process, cross-linking the silicone and leaching
out the PVDF with HFIP unaffecting the silicone.
[0064] Foams as described herein can be useful as a flexible foam
used in furniture cushions, pillows, mattresses, padded dashboards,
run flat tire fillings, packaging material, upholstery, bedding,
and automotive seating, insulation panels, microcellular foam seals
and gaskets, durable elastomeric materials, automotive suspension
bushings, electrical potting compounds, seals, gaskets, and carpet
underlay.
[0065] Rigid foams are also within the scope of the present
description and can be used for thermal insulation such as in
household refrigerators and freezers, cold-storage rooms and
buildings, foil-faced rigid foam boards for construction,
stressed-skin panels for construction, refrigerated truck bodies,
food and drink coolers, spray flat-roof systems and transfer
molding cores.
[0066] Foams can also be in the form of soft elastomers used for
gel pads and print rollers, air filtration parts and in footwear.
Foams as described herein can also be formed as hard plastics and
moldings used in electronic instrument bezels, structural parts,
wheels for heavy machinery, skateboards, inline skates, wheelchairs
and the like, car parts such as steering wheels and fenders,
surfboards, boat hulls, flooring material, door frames, columns,
balusters, window headers, pediments, medallions, rosettes,
imitation wood furniture and windmill and airplane wings.
[0067] Flexible plastic foams are also within the scope of the
present description and can be used as straps and bands such a
tennis grips and watch bands, waterproof and windproof properties
in outerwear, diapers, shower curtains and inflatable rafts.
[0068] The foams described herein can be used in a variety of
medical uses such as wound dressings, implantable medical devices,
dermal fillers, artificial bones, surgical tools and instruments,
artificial joints, and the like. Further, they can be useful in
general surgery as tapes, postmammoplasty supports, as facial and
postrhytidectomy dressings, over leg grafts, postpilonidal pad
dressings and axillary pad dressings.
[0069] Other methods for producing foam-like materials in an
industrial setting are described. An overview of exemplary
possesses is illustrated in FIG. 10. As a first step 100, an
appropriate base material is chosen. FIGS. 11 and 12 illustrate an
exemplary base material ready for coating as described herein. As
illustrated, the base material forms interconnections between
struts 200. FIG. 11A illustrates a cross-section of strut 200 which
has a triangular shape 202. It is appreciated by one skilled in the
art that a triangular strut shape is one of an almost infinite set
of geometries that a strut can assume.
[0070] Batch processing, reel to reel processing, and/or conveyor
belt processing can be used in the application of one or more fluid
materials in order to achieve a high throughput of material, such
as on an industrial scale. In a conveyer belt system, formation of
a foam-like material or processed foam-like material can be
accomplished sequentially in stations or as a continuous process.
Bath processing can also be combined with a conveyer belt system
wherein several foam-like materials can be produced
simultaneously.
[0071] In a second step 110, a fluid material is applied to the
base material. A fluid material is applied via a coating technique
such as, but not limited to, curtain application, spraying,
knifing, dipping, and the like. The application of the fluid
material can have varying parameters. For example, an airknife
blade can be used to remove residual fluid material; however, an
airknife need not be use in some embodiments. Likewise, heating of
the fluid material can be varied or even not used. Further, a
vacuum need or need not be used to facilitate fluid material
intrusion into the pores of the base material. Other non-limiting
parameters that can be varied include temperature programs, air
velocity, pressure, speed of material traveling on conveyor belt,
number of coating stations/nozzles, number of airknife
stations/nozzles, and number of suction locations to obtain various
thicknesses and uniformities of the conformal coat.
[0072] Other steps to remove excess fluid material include, but are
not limited to, using a vacuum to draw the fluid into the porous
surface, using an airknife to blow away excess fluid material,
using another means of positive pressure, pressing the base
material to squeeze out excess fluid material or a combination of
those procedures.
[0073] After the fluid material has been properly applied to the
base material, the fluid material is cured 120. The fluid material
is cured via exposure to an element which activates crosslinking,
curing, setting, gelling, solidification, and/or any sort of phase
change into a stable form of the fluid material. The method of
curing can be different depending on the particular application.
For example, RTV silicones can be cured by application of heat, or
moist hot air or through addition (e.g., by spraying overtop) of
cross-linker and activation of the cross-linker. Hydrogels, on the
other hand, can be cross-linked using UV activated cross-linkers,
peroxide cross-linkers which are activated by heat, or other
cross-linkers which are activated by the addition of a catalyst.
Further still, curing can be achieved by simple devolitilization on
the conveyer belt, precipitation out of solution, and/or
solidification by cooling (e.g., if the polymer is applied in a
molten state).
[0074] FIGS. 11 B-D illustrate a cross section of strut 200 coated
two times (FIG. 11 B), four times (FIG. 11 C) and six times (FIG.
11 D). Triangular strut shape 202 can be seen in each circumstance
with the coating layer 204 growing larger and larger with each
additional coating step. FIGS. 12 B-D illustrate, again, the porous
base material coated two times, four times and six times
respectively.
[0075] Next, the base material is removed 130, or leached away,
leaving a foam like-material 140 of interest. Here the leaching
agent can be sprayed and/or curtain coated onto the cured fluid
material/base material composite member, and/or the composite
member can be passed through a pool of the leaching agent, or
through rollers which apply the leaching agent and squeeze out the
air. The leaching can be followed in a similar fashion with a
washing step to remove the leaching agent and/or help remove the
excess unremoved, unwanted material.
[0076] Optionally, the coating and curing steps can be repeated
using a post processing step 150. The advantage of repeating the
coating and curing steps after the leaching is threefold. 1) If the
cured fluid material is partly adversely affected during the
leaching step, the application of additional fluid material post
leaching can help increase the strength of the cured fluid
material. 2) If a fluid material of choice is adversely affected by
the post leaching step, a primary sacrificial layer of a first
fluid material that is not affected by the leaching step is applied
first, then the base material is leached out and the fluid material
of choice is then applied unto the empty primary sacrificial layer.
The primary sacrificial layer can then be leached by an alternative
method that would not affect the fluid material of choice. Hence,
the fluid material is cured and left behind unaffected. 3) To fill
the void created by leaching out the base material.
[0077] FIG. 13 A illustrates a foam-like material 300 wherein the
base material has been leached out. In FIG. 13 A, void 302 exists
where a triangular base member strut previously existed. FIGS. 13
B-E illustrate foam-like material 300 further coated one time, two
times, three times and four times respectively. FIGS. 13 A-E
illustrate the thickness of the material as further coatings are
applied to the foam-like material 300.
[0078] After the post processing step, a processed foam-like
material remains having additional coatings and potentially filled
voids wherein the base material previously resided. Such a material
can be stronger than a non-processed foam-like material. However, a
strong foam-like material can produced in some embodiments without
the need for optional post processing step(s). For example, a
foam-like material substantially formed from a metal fluid material
may not need to be subjected to post processing steps.
Example 1
Process for Making a Foam-Like Material
[0079] A polyurethane open celled foam (the base material) is
coated as described herein using a solution of silicone HTV 30% w/v
(the fluid material), by either dipping the polyurethane foam in
the solution, casting the solution on a sheet of polyurethane or
spraying the solution in excess over the sheet of polyurethane. The
excess solution is removed by squeezing out the foam, or by vacuum
which is applied through a Buchner funnel at the bottom of the foam
(in the case of casting the solution over the foam) or by blowing
air over the foam as in the case of an air-knife, or in combination
of any of the aforementioned.
[0080] The foam is then devolitilized in vacuum or by application
of mild heat in the case of HTV silicone, such that the solvent is
removed, but the HTV silicone is not cured. This can be achieved in
the application of the air current during the previous step (the
air may or may not be heated).
[0081] Finally, the fluid material is cured and the coating layer
is affixed unto the foam. The process may be repeated from 1 to
about 1000 times (more specifically 1 to 10 times) to achieve
various builds (final pore densities)). The polyurethane base
material is completely removed from the center of the structure by
digestion in hydrogen peroxide/water solution with or without the
presence of metal ions and with or without heating. Alternatively,
the polyurethane foam can be degraded out by 37% HCl digestion for
1-5 minutes, with vigorous agitation and air removal to facilitate
the uniform digestion of the polyurethane, and a subsequent DMSO
wash to remove the remnant degradants which are not soluble in the
37% HCl. The degradation/leaching steps can be repeated 1-20 times
to achieve various levels of purity. The resulting material is a
substantially pure silicone foam-like material.
Example 2
Coating a Base Material
[0082] A sheet of polyurethane open celled foam base material
(20.times.20 cm) is placed in a container the bottom of which is a
fine grate. Vacuum is applied to the bottom of the grate to pull
air through the top of the foam into the foam and finally through
the grate and out. A solution of about 20% HTV silicone (platinum
cured, the fluid material) in chloroform is cast over the foam and
pulled through the foam by the vacuum, a jet of air is applied to
the foam through an air-knife to remove any remaining solution
droplets that are trapped in the foam to clean out the pores. The
foam is then devolitized in vacuum at about room temperature for 2
hours. The devolitized foam is finally cured at 120.degree. C. for
1 hour. The process is repeated 3 times. The resulting material is
an open celled polyurethane base foam, conformably coated by an
approximately 50 .mu.m layer of silicone.
Example 3
An Alternate Method of Coating a Base Material
[0083] A foam-like material is produced substantially in accordance
with Example 1, except that instead of a polyurethane foam base
material, a melamine foam is used as the base material. In
addition, the base material is not removed from the silicone foam.
The resulting foam-like material comprises a highly porous, open
celled structure having a melamine base and a silicone
overcoat.
Example 4
Bath Processing Method of Coating a Base Material
[0084] A set of ten 5 cm.times.5 cm polyurethane open celled foams
are loaded into a coating tray and placed on a circular conveyer
belt. The belt is moved into the first station wherein the open
celled foams are coated using a solution of silicone HTV 30% w/v,
by spraying the solution in excess over the sheet of polyurethane.
On the way to the second station, the sprayed batch of open celled
foams is subjected to an airknife wherein the excess solution is
removed from the foams.
[0085] At the second station, the foam is then devolitilized by
application of mild heat such that the solvent is removed from the
applied solution, but the HTV silicone is not cured. After heating,
the fluid material is cured and the coating layer is affixed unto
the polyurethane foam. The process is repeated 4 times to achieve
the proper pore density. The repetition of layers is achieved by
the circular conveyer belt with multiple passes through the
system.
[0086] Then, the bath of coated foams is diverted from the circular
conveyer belt and onto an auxiliary belt. At the next station, the
polyurethane base material is completely removed from the center of
the structure by digestion in hydrogen peroxide/water solution
without heat. The resulting material is a substantially pure
silicone foam-like material.
[0087] The foam-like materials are then diverted to another
circular conveyer belt to be further coated as described above. The
foam-like materials are coated an additional four times resulting
in a processed foam-like material that is stronger.
Example 5
Forming a Composite Material
[0088] A sheet of polyurethane open celled foam base material
(20.times.20 cm) is placed in a container the bottom of which is a
fine grate. Vacuum is applied to the bottom of the grate to pull
air through the top of the foam into the foam and finally through
the grate and out. A solution of MED-4850, a high durometer
silicone, is cast over the foam and pulled through the foam by the
vacuum, a jet of air is applied to the foam through an air-knife to
remove any remaining solution droplets that are trapped in the foam
to clean out the pores. The foam is then devolitized in vacuum at
about room temperature for 2 hours and cured at 120.degree. C. for
1 hour.
[0089] Then, a second coating is applied by casting a solution of
MED-4830, a lower durometer silicone, over the cured first coating.
The solution is pulled through the foam by the vacuum, a jet of air
is applied to the foam through an air-knife to remove any remaining
solution droplets that are trapped in the foam to clean out the
pores. The foam is then devolitized in vacuum at about room
temperature for 2 hours and cured at 120.degree. C. for 1 hour.
[0090] Then, a third coating is applied by casting a solution of
MED-4815, an even lower durometer silicone, over the cured second
coating. The solution is pulled through the foam by the vacuum, a
jet of air is applied to the foam through an air-knife to remove
any remaining solution droplets that are trapped in the foam to
clean out the pores. The foam is then devolitized in vacuum at
about room temperature for 2 hours and cured at 120.degree. C. for
1 hour.
[0091] Then, a fourth final coating is applied by casting a
solution of MED-4801, the lowest durometer silicone used, over the
cured third coating. The solution is pulled through the foam by the
vacuum, a jet of air is applied to the foam through an air-knife to
remove any remaining solution droplets that are trapped in the foam
to clean out the pores. The foam is then devolitized in vacuum at
about room temperature for 2 hours and cured at 120.degree. C. for
1 hour.
[0092] The resulting material is an open celled polyurethane base
foam, conformably coated by an approximately 200 .mu.m layer of
decreasing durometer silicone. The polyurethane base material can
be optionally removed from the composite member. Other composite
materials can be similarly made.
Example 6
[0093] A 20 cm diameter disc (3 mm thick) of polyurethane open
celled foam with a pore density of 40 ppi (the base material) is
coated as described herein using a dispersion of Viton.RTM. HTV 20%
w/w in Methyl Ethyl Ketone (a fluoroelastomer available from DuPont
Dow Elastomers), by casting the dispersion in excess onto the base
material placed in a Buchner funnel. The excess dispersion is
removed by vacuum which is applied through the Buchner funnel at
the bottom of the foam. The fluid material coated base material is
then transferred from the Buchner funnel to a fine metal grate and
an air-knife set to 100 psi is used to remove any remaining fluid
material and ensure the open cell nature of the composite material
(fluid material coated base material). The composite material is
then placed in an oven for 1 hour at 126.degree. C. to cure the
Viton.RTM. fluid material. The composite material is then coated
with the fluid material and cured in an oven in the same process
five additional times. The resulting composite material is then
leached for 24 hours in Dimethyl Sulfoxide with vigorous agitation
to remove the polyurethane base material. After 24 hours the
resulting material is washed in DI water for 5 minutes and then
heated to 180.degree. C. to remove the excess Dimethyl Sulfoxide.
The resulting material is a substantially pure fluoroelastomeric
foamlike material.
Example 7
[0094] A 15 cm diameter disc (5 mm thick) of polyurethane open
celled foam with a pore density of 70 ppi (the base material) is
coated as described herein using a dispersion of Styrene Isoprene
Styrene 14% Styrene at 25% w/w in Xylene (the fluid material), by
casting the dispersion in excess onto the base material placed in a
Buchner funnel. The excess dispersion is removed by vacuum which is
applied through the Buchner funnel at the bottom of the foam. The
fluid material coated base material is then transferred from the
Buchner funnel to a fine metal grate and an air-knife set to 150
psi is used to remove any remaining fluid material and ensure the
open cell nature of the composite material (fluid material coated
base material). The composite material is then allowed to dry for
30 minutes at room temperature. The composite material is then
coated with the fluid material and dried in the same process two
additional times. The resulting composite material is then leached
for 48 hours in Dimethyl Sulfoxide with gentle agitation to remove
the polyurethane base material. After 48 hours the resulting
material is washed in DI water for 30 minutes and dried. The
resulting material is a substantially pure Styrene Isoprene Styrene
foamlike material.
[0095] While this invention has been described with respect to
various specific examples and embodiments, it is to be understood
that the invention is not limited thereto and that it can be
variously practiced within the scope of the invention.
[0096] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the specification and
attached claims are approximations that may vary depending upon the
desired properties sought to be obtained by the present invention.
At the very least, and not as an attempt to limit the application
of the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques. Notwithstanding that the numerical ranges and
parameters setting forth the broad scope of the invention are
approximations, the numerical values set forth in the specific
examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily
resulting from the standard deviation found in their respective
testing measurements.
[0097] The terms "a," "an," "the" and similar referents used in the
context of describing the invention (especially in the context of
the following claims) are to be construed to cover both the
singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. Recitation of ranges of values
herein is merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range. Unless otherwise indicated herein, each individual value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein is intended
merely to better illuminate the invention and does not pose a
limitation on the scope of the invention otherwise claimed. No
language in the specification should be construed as indicating any
non-claimed element essential to the practice of the invention.
[0098] Groupings of alternative elements or embodiments of the
invention disclosed herein are not to be construed as limitations.
Each group member may be referred to and claimed individually or in
any combination with other members of the group or other elements
found herein. It is anticipated that one or more members of a group
may be included in, or deleted from, a group for reasons of
convenience and/or patentability. When any such inclusion or
deletion occurs, the specification is deemed to contain the group
as modified thus fulfilling the written description of all Markush
groups used in the appended claims.
[0099] Certain embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. Of course, variations on these described embodiments
will become apparent to those of ordinary skill in the art upon
reading the foregoing description. The inventor expects skilled
artisans to employ such variations as appropriate, and the
inventors intend for the invention to be practiced otherwise than
specifically described herein. Accordingly, this invention includes
all modifications and equivalents of the subject matter recited in
the claims appended hereto as permitted by applicable law.
Moreover, any combination of the above-described elements in all
possible variations thereof is encompassed by the invention unless
otherwise indicated herein or otherwise clearly contradicted by
context.
[0100] In closing, it is to be understood that the embodiments of
the invention disclosed herein are illustrative of the principles
of the present invention. Other modifications that may be employed
are within the scope of the invention. Thus, by way of example, but
not of limitation, alternative configurations of the present
invention may be utilized in accordance with the teachings herein.
Accordingly, the present invention is not limited to that precisely
as shown and described.
* * * * *