U.S. patent application number 11/406226 was filed with the patent office on 2007-08-23 for carbon foam thermal core.
Invention is credited to Yevgeniy Pavlovich Griffin, Douglas Miller, Mark Segger.
Application Number | 20070193158 11/406226 |
Document ID | / |
Family ID | 38625558 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070193158 |
Kind Code |
A1 |
Miller; Douglas ; et
al. |
August 23, 2007 |
Carbon foam thermal core
Abstract
A cold storage panel, which includes a carbon foam core having a
high ratio of compressive strength to density, desirable fire
retardant properties, and resistance to environmental stress. The
carbon foam insulated panel also includes a first layer and a
second layer bound to a first surface and second surface of the
carbon foam core. Applications of the carbon foam structural
insulated panel include structural and fire retardant elements of
residential and commercial refrigerators and freezers, food
lockers, coolers, and the like.
Inventors: |
Miller; Douglas; (North
Olmsted, OH) ; Segger; Mark; (Strongsville, OH)
; Griffin; Yevgeniy Pavlovich; (Macedonia, OH) |
Correspondence
Address: |
WADDEY & PATTERSON, P.C.
1600 DIVISION STREET, SUITE 500
NASHVILLE
TN
37203
US
|
Family ID: |
38625558 |
Appl. No.: |
11/406226 |
Filed: |
April 18, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11314975 |
Dec 21, 2005 |
|
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11406226 |
Apr 18, 2006 |
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Current U.S.
Class: |
52/309.9 |
Current CPC
Class: |
B32B 2509/10 20130101;
C04B 41/009 20130101; F25D 2201/126 20130101; C01B 32/00 20170801;
B32B 29/007 20130101; B32B 2264/108 20130101; C04B 2235/9607
20130101; B32B 13/045 20130101; B32B 9/007 20130101; C04B 2235/652
20130101; B32B 2307/304 20130101; C04B 2235/48 20130101; B32B
2307/3065 20130101; F25D 23/065 20130101; C04B 2235/96 20130101;
C04B 41/009 20130101; C04B 38/0032 20130101; B32B 5/30 20130101;
B32B 2255/102 20130101; B32B 2307/714 20130101; B32B 21/047
20130101; B32B 7/12 20130101; E04B 1/80 20130101; C04B 2235/77
20130101; B32B 2266/0285 20130101; B32B 5/18 20130101; C04B 41/5092
20130101; C04B 41/85 20130101; B32B 15/046 20130101; C04B 35/524
20130101; B32B 5/16 20130101; C04B 38/0032 20130101; E04C 2/296
20130101; E04C 2/292 20130101; C04B 35/52 20130101; C04B 35/52
20130101; C04B 38/00 20130101; C04B 2111/28 20130101 |
Class at
Publication: |
052/309.9 |
International
Class: |
E04C 1/00 20060101
E04C001/00 |
Claims
1. A cold storage panel comprising a carbon foam material with a
density of from about 0.08 g/cc to about 0.16 g/cc.
2. The panel of claim 1 further comprising: a first outer layer
bound to a first surface of the carbon foam material; and a second
outer layer bound to a second surface of the carbon foam
material.
3. The panel of claim 1 wherein the carbon foam material has a
ratio of compressive strength to density of at least about 20
MPa/g/cc.
4. The panel of claim 1 wherein the carbon foam material has a
thermal conductivity of from about 0.06 W/mK to about 0.3 W/mK.
5. The panel of claim 1 wherein the carbon foam material includes a
coating on the carbon foam's exterior surface.
6. The panel of claim 6 wherein the coating improves fire
retardancy of the carbon foam material.
7. The panel of claim 6 wherein the coating improves oxidation
resistance of the carbon foam material.
8. The panel of claim 1 further comprising a layer of compressed
particles of exfoliated graphite on at least one surface of the
carbon foam material.
9. The panel of claim 2 wherein the outer layers are selected from
the group consisting of paper, reinforced paper composites,
oriented strand board, fiberboard, drywall, gypsum, gypsum
composites, wood, wood composites, plywood, thermoplastics, plastic
composites, resins, metals, metal alloys, metal composites, and
combinations thereof.
10. A cold storage panel comprising a carbon foam material having a
ratio of compressive strength to density of at least about 20
MPa/g/cc.
11. The panel of claim 10 further comprising: a first outer layer
bound to a first surface of the carbon foam material; and a second
outer layer bound to a second surface of the carbon foam
material.
12. The panel of claim 10 wherein the carbon foam material with a
density of from about 0.08 g/cc to about 0.16 g/cc.
13. The panel of claim 10 wherein the carbon foam material has a
thermal conductivity of from about 0.06 W/mK to about 0.3 W/mK.
14. The panel of claim 10 wherein the carbon foam material includes
a coating on the carbon foam's exterior surface.
15. The panel of claim 14 wherein the coating improves fire
retardancy of the carbon foam material.
16. The panel of claim 14 wherein the coating improves oxidation
resistance of the carbon foam material.
17. The panel of claim 10 further comprising a layer of compressed
particles of exfoliated graphite on at least one surface of the
carbon foam material.
18. The panel of claim 11 wherein the outer layers are selected
from the group consisting of paper, reinforced paper composites,
oriented strand board, fiberboard, drywall, gypsum, gypsum
composites, wood, wood composites, plywood, thermoplastics, plastic
composites, resins, metals, metal alloys, metal composites, and
combinations thereof
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part of copending and
commonly assigned U.S. Patent Application having Ser. No.
11/314,975, entitled "Carbon Foam Structural Insulated Panel" filed
on Dec. 21, 2005 in the names of Miller, Griffin and Segger, the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to the use of a carbon foam
material as the core for structural panels for cold storage
applications, such as commercial and residential refrigerators and
freezers, food lockers, coolers, refrigerated rooms and holds, and
the like. More particularly, the present invention relates to the
use of carbon foam in insulated panels which provide insulation
while also being non-flammable and which do not release noxious
gases when exposed to flame.
[0004] 2. Background Art
[0005] Many cold storage panels are formed using a core material of
an expanded polymeric foam like expanded polystyrene (EPS). The EPS
or other foam is conventionally sandwiched between outer panels
depending on the specific application. For instance, when the panel
is used to form a relatively large structure such as a food locker
or refrigerated room, the foam can be sandwiched between layers of
oriented strand board, fiber board, plywood, or other like
materials. Alternatively, the outer layers can be formed of a metal
sheet, such as a thin layer of steel. When the panel is used to
form a smaller structure, such as a cooler or a refrigerator or
freezer, the core is sandwiched between a plastic material such as
a high density polyethylene (HDPE). While this type of panel is
well understood and possesses adequate insulative value, EPS and
other polymeric materials are flammable when exposed to heat, are
subject to chemical degradation and emit noxious gases when
burned.
[0006] What is desired, therefore, is a core material for a panel
for cold storage applications which possesses at least adequate
insulative value (preferably a thermal R value of at least about 2,
and as high as about 4 or higher), while being relatively
non-flammable, resistant to chemical degradation and which does not
emit noxious gases when exposed to flame. The desired core material
should also be light weight, have a high strength to density ratio,
can be recycled, can be used in thinner sections, is inert and
non-corrosive and resists deterioration over time. Certain carbon
foams provide just such a material.
[0007] In Hardcastle et al. (U.S. Pat. No. 4,425,396) an insulating
panel is disclosed with a synthetic organic polymeric foam with
protective weathering layers comprised of multiple thermoplastic
sheets.
[0008] Cahill (U.S. Pat. No. 6,656,858) describes a lightweight
laminate wall comprised of a low density layer of from about 0.5 to
3 pounds per cubic foot and a second, reinforcing layer of a
polymeric fabric. These structures are lightweight, have a low
moisture resistance and meet building code requirements regarding
transverse wind loading.
[0009] Porter (U.S. Pat. No. 6,599,621) describes a structural
insulated panel (SIP) with high strength and resistance to fire and
particularly to water and changes in humidity. The disclosed
structures are comprised of an inner insulating core with a gypsum
fiberboard on one face of the insulating core and an oriented
strand board on the second face of the insulating core. Preferably,
the insulating core is comprised of a plastic foam such as expanded
polystyrene or urethane which is bonded to both the gypsum
fiberboard and the oriented strand board.
[0010] Porter (U.S. Pat. No. 6,588,172) describes the incorporation
of a laminated layer of plastic impregnated paper into a SIP to
increase the panel's tensile strength while rendering it impervious
to moisture. This layer is typically situated between the gypsum
board and plastic foam core, adhered through a conventional bonding
agent.
[0011] Parker (U.S. Pat. No. 4,628,650) describes a SIP with a foam
core with a layer having an overhang projecting from the foam core
edges. The overhang is situated to facilitate an effective seal
between adjacent SIPs, providing better thermal insulation.
Additionally, the core of the panels has channels through the
structure for the placement of joists, studs or rafters.
[0012] Clear (U.S. Pat. No. 6,079,175) describes a SIP of
cementitious material for building structures. A lightweight fill
material such as bottom ash, cement and water is poured between
spaces of two outermost ribs, which is claimed to provide
insulation, strength and also rigidity to the panel and therefore
the structure the panel comprises. This SIP has the advantage of
being constructed in remote or more barren areas as it is fairly
inexpensive to create.
[0013] Pease (U.S. Pat. No. 6,725,616) prepares an insulated
concrete wall either cast or built with blocks which is attached to
reinforced insulated strips. The patentee indicates that users will
require less time and labor in making insulated using the
patentee's method of fixing reinforced rigid foam to the surface of
a concrete wall.
[0014] Pease (U.S. Pat. No. 6,892,507) describes a method and
apparatus for making an SIP with a rigid foam sheet. The rigid foam
sheets have multiple grooves in which reinforcing strips are
situated. The strips and rigid foam are then covered and bonded
with a reinforcing sheet, the sheet providing both structural
support and moisture retention.
SUMMARY OF THE INVENTION
[0015] The present invention provides a cold storage panel having a
carbon foam core, which is uniquely capable of being used in
applications requiring good insulative value, is non-flammable and
resistant to chemical degradation and which does not emit noxious
gases when exposed to flame. Moreover, since the carbon foam core
material can provide adequate insulative value in thinner sheets
than conventional foams, the inventive panels can be made thinner
than conventional panels, thus providing significant space and cost
savings.
[0016] The inventive carbon foam panel exhibits a density,
compressive strength and compressive strength to density ratio to
provide a combination of strength and relatively light weight
characteristics not heretofore seen. In addition, the carbon
lattice work of the carbon foam resists both charring and
combustion while maintaining structural integrity in environmental
conditions from high humidity to severely low temperatures.
Furthermore, the carbon foam can be produced in a desired size and
configuration and can be readily machined for a specific size for a
cold storage panel.
[0017] More particularly, the inventive carbon foam cold storage
panel has a carbon foam core with a density of from about 0.08 to
about 0.16 grams per cubic centimeter (g/cc) and a compressive
strength of at least about 5 megaPascals (MPa), more preferably at
least about 6 MPa (measured by, for instance, ASTM C695). An
important characteristic for the carbon foam core when intended for
use in larger scale applications such as walk-in refrigerators and
freezers, food lockers, etc. is a strength to density ratio of at
least about 20 MPa/g/cc, more preferably at least about 33
MPa/g/cc, most preferably at least about 37.5 MPa/g/cc, and
higher.
[0018] The inventive carbon foam panel should have the carbon foam
core of a relatively uniform density both longitudinally and
latitudinally for consistent thermal insulation and strength
characteristics throughout the panel. Specifically, the carbon foam
should have a relatively uniform distribution of pores in order to
provide the required high compressive strength, the pores being
relatively isotropic. In addition, the carbon foam core should have
a total porosity of about 65% to about 95%, more preferably about
70% to about 95% to create the optimal strength to density ratio of
the carbon foam structural insulated panel.
[0019] Advantageously, to produce the carbon foam core, a polymeric
foam block, particularly a phenolic foam block, is carbonized in an
inert or air-excluded atmosphere, at temperatures which can range
from about 500.degree. C., more preferably at least about
800.degree. C., up to about 3200.degree. C. to prepare the carbon
foams for use in the structural carbon foam panels.
[0020] Prior to the addition of outerlayers, the carbon foam core
can be treated with a variety of coatings to improve the overall
performance of the carbon foam cold storage panel. For example, an
anti-oxidation coating can be applied to the carbon foam to
increase the longevity of the panel in highly oxidative conditions.
Additionally, a fire retardant coating could also be applied to the
carbon foam core to further increase the integrity of the carbon
foam core and thus the panel, when exposed to extreme
temperatures.
[0021] Most commonly, the carbon foam core's first and second
outerfaces are each covered with a layer to form the inventive cold
storage panel. Optionally, the outer layers may be comprised of
oriented strand board (OSB) or a variety of gypsum board, or
combinations thereof. Other outerlayers exist including, but not
limited to, a variety of thermoplastics, metals, organic sheets,
fiber impregnations, and composite boards.
[0022] The carbon foam core should be bound to the outer layers to
construct the cold storage panel. Binding may be through the use of
materials such as adhesives or cements which create a chemical
interaction between the outer layers and the carbon foam core.
These include binders specific to carbon foam applications as well
as general cements, mastics or high temperature glue. Optionally,
mechanical materials can be used.
[0023] Alternatively, the carbon foam can be formed having a higher
density, about 0.2 to about 0.6 or higher, for instance, sealed,
and used as a cold storage panel without outerlayers.
[0024] An object of the invention, therefore, is a carbon foam
panel having characteristics which enable it to be used in cold
storage applications requiring an R value of at least about 2, and
is non-flammable and resistant to chemical degradation and which
does not emit noxious gases when exposed to flame.
[0025] Another object of the invention is a cold storage panel
having a carbon foam core, with the structure of the carbon foam
core having a sufficiently high compressive strength to be used for
high stress applications.
[0026] Still another object of the invention is carbon foam panel
where the carbon foam core provides a fire retardant barrier, and
which is extremely resistant to both combustion and charring.
[0027] Yet another object of the invention is an insulated foam
panel which can be produced in a desired size and configuration,
where the carbon foam core can be machined or joined with other
similar carbon foam sheets to provide larger carbon foam
panels.
[0028] Another object of the invention is to provide an insulated
panel which is resistant to environmental stresses including high
humidity and severe temperature fluctuations.
[0029] Still another object of the invention is to provide a carbon
foam insulated panel where the carbon foam core provides adequate
thermal insulation to maintain a temperature differential between
the one side of the panel and the opposing side of the panel.
[0030] These aspects and others that will become apparent to the
artisan upon review of the following description can be
accomplished by providing a carbon foam panel with a carbon foam
core having an R value of at least about 2, more preferably as high
as about 4 or higher. The foam core preferably has a ratio of
compressive strength to density of at least about 20 MPa/g/cc,
especially a ratio of compressive strength to density of at least
about 33 MPa/g/cc, and most advantageously a ratio of at least
about 37.5 MPa/g/cc. The inventive cold storage panel has a carbon
foam core with a density of from about 0.08 g/cc to about 0.16
g/cc, more preferably of from about 0.11 g/cc to about 0.15 g/cc,
and a compressive strength of at least about 5 MPa, more preferably
at least about 6 MPa, with a porosity of between about 65% and
about 95%. Furthermore the thermal conductivity of the carbon foam
core is from about 0.06 W/mK to about 0.3 W/mK.
[0031] Furthermore, the carbon foam core can be produced by
carbonizing a polymer foam article, especially a phenolic foam, in
an inert or air-excluded atmosphere. The phenolic foam precursor
for the carbon foam core should preferably have a compressive
strength of at least about 100 pounds per square in (psi).
[0032] It is to be understood that both the foregoing general
description and the following detailed description provide
embodiments of the invention and are intended to provide an
overview or framework of understanding to nature and character of
the invention as it is claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a view of a carbon foam cold storage panel in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] Carbon foams in accordance with the carbon foam core of the
present invention are prepared from polymeric foams, such as
polyurethane foams or phenolic foams, with phenolic foams being
preferred. Phenolic resins are a large family of polymers and
oligomers, composed of a wide variety of structures based on the
reaction products of phenols with formaldehyde. Phenolic resins are
prepared by the reaction of phenol or substituted phenol with an
aldehyde, especially formaldehyde, in the presence of an acidic or
basic catalyst. Phenolic resin foam is a cured system composed of
open and closed cells. The resins are generally aqueous resoles
catalyzed by sodium hydroxide at a formaldehyde:phenol ratio which
can vary, but is preferably about 2:1. Free phenol and formaldehyde
content should be low, although urea may be used as a formaldehyde
scavenger.
[0035] The foam is prepared by adjusting the water content of the
resin and adding a surfactant (eg, an ethoxylated nonionic), a
blowing agent (eg, pentane, methylene chloride, or
chlorofluorocarbon), and a catalyst (eg, toluenesulfonic acid or
phenolsulfonic acid). The sulfonic acid catalyzes the reaction,
while the exotherm causes the blowing agent, emulsified in the
resin, to evaporate and expand the foam. The surfactant controls
the cell size as well as the ratio of open-to-closed cell units.
Both batch and continuous processes are employed. In the continuous
process, the machinery is similar to that used for continuous
polyurethane foam. The properties of the foam depend mainly on
density and the cell structure.
[0036] The preferred phenol is resorcinol, however, other phenols
of the kind which are able to form condensation products with
aldehydes can also be used. Such phenols include monohydric and
polyhydric phenols, pyrocatechol, hydroquinone, alkyl substituted
phenols, such as, for example, cresols or xylenols; polynuclear
monohydric or polyhydric phenols, such as, for example, naphthols,
p.p'-dihydrexydiphenyl dimethyl methane or hydroxyanthracenes.
[0037] The phenols used to make the foam starting material can also
be used in admixture with non-phenolic compounds which are able to
react with aldehydes in the same way as phenol.
[0038] The preferred aldehyde for use in the solution is
formaldehyde. Other suitable aldehydes include those which will
react with phenols in the same manner. These include, for example,
acetaldehyde and benzaldehyde.
[0039] In general, the phenols and aldehydes which can be used in
the process of the invention are those described in U.S. Pat. Nos.
3,960,761 and 5,047,225, the disclosures of which are incorporated
herein by reference.
[0040] Optionally, the carbon foam core of the inventive panel can
be created for an increased oxidation resistance by the specific
inclusion of compounds solely for improving the oxidation
resistance of the carbon foam. Such solid oxidation inhibiting
additives include ammonium phosphate, aluminum phosphate, zinc
phosphate or boric acid. An additional characteristic of the
oxidation inhibiting additives is that the additives can be added
during either the resin production stage or the phenolic foam
forming stage of carbon foam production. Using either method, the
final carbonization of the phenolic foam results in phosphorous or
boron retained within the carbon foam structure that reduces the
rate of oxidation of the carbon foam. Specifically, phosphorous or
boron retained in the final carbon foam product from about 0.01% to
about 0.5% by weight reduces the rate of oxidation by over 50%.
[0041] Alternatively, the carbon foam product can be treated with
an oxidation-inhibiting agent after the completion of the
carbonization process but prior to the integration in the panel.
The preferred method would be to impregnate the carbon foam with
aqueous solutions of phosphorous-containing materials such as
ammonium phosphate, phosphoric acid, aluminum phosphate, or zinc
phosphate, followed by a heat treatment to about 500.degree. C. to
simultaneously remove the water and fix the phosphorous to the
carbon. Additionally, water-soluble boron compounds such as boric
acid can be introduced in the above manner to create an
oxidation-resistant carbon foam product.
[0042] The polymeric foam used as the starting material in the
production of the carbon foam core should have an initial density
which mirrors the desired final density for the carbon foam which
is to be formed. In other words, the polymeric foam should have a
density of about 0.08 g/cc to about 0.16 g/cc. The cell structure
of the polymeric foam should be closed with a porosity of between
about 65% and about 95% and a relatively high compressive strength,
i.e., on the order of at least about 100 psi, and as high as about
300 psi or higher.
[0043] In order to convert the polymeric foam to carbon foam, the
foam is carbonized by heating to a temperature of from about
500.degree. C., more preferably at least about 800.degree. C., up
to about 3200.degree. C., in an inert or air-excluded atmosphere,
such as in the presence of nitrogen. The heating rate should be
controlled such that the polymer foam is brought to the desired
temperature over a period of several days, since the polymeric foam
can shrink by as much as about 50% or more during carbonization.
Care should be taken to ensure uniform heating of the polymer foam
piece for effective carbonization.
[0044] By use of a polymeric foam heated in an inert or
air-excluded environment, a non-graphitizing glassy carbon foam is
obtained, which has the approximate density of the starting polymer
foam, but a compressive strength of at least about 5 MPa and,
significantly, a ratio of strength to density of at least about 20
MPa/g/cc, more preferably at least about 33 MPa/g/cc. The carbon
foam has a relatively uniform distribution of isotropic pores
having, on average, an aspect ratio of between about 1.0 and about
1.5.
[0045] Referring now to FIG. 1, there is revealed a partial side
view of a cold storage panel 10 with a carbon foam core 12 in
accordance with one of the embodiments of the present
invention.
[0046] Carbon foam core 12 and panel 10 are generally planar,
though can be constructed to meet a variety of specifications.
Optionally, carbon foam core 12 can be curved or possess rounded
edges through either machining or molding to best fit the desired
cold storage application.
[0047] Cold storage panel 10 includes both the first outer layer 14
and second outer layer 16 situated on the opposite outer surfaces
of carbon foam core 12. As with carbon foam core 12 and panel 10,
both the first outer layer 14 and the second outer layer 16 can
possess a variety of shapes for the desired application. The first
outer layer 14 and the second outer layer 16 can comprise similar
or completely different materials depending upon the specific
structural application of the panel. These materials include
typical construction materials such as plywood, oriented strand
board, drywall, gypsum, cement composites, wood composites, or a
variety of other rigid organic or inorganic construction boards.
Furthermore, first outer layer 14 and second outer layer 16 can
also be impregnations of the above materials or include
thermoplastics, resins, carbon composites, ceramic composites or a
variety of other artificially created materials. In certain cases
these layers can include thin metal skins around carbon foam core
12, or outer layer 14 and outer layer 16 can include hardened metal
composites. Obviously, the selection of first outer layer 14 and
the second outer layer 16 will be based on the necessary tensile
strength and fire retardant and insulative properties of the
specific panel 10. Furthermore, first outer layer 14 and second
outer layer 16 can be of two different materials where the use of
panel 10 necessitates such properties. Other materials which can
comprise either one or both of the outer layers 14 and 16 include
but are not limited to the following: paper, reinforced paper
composites, oriented strand board, fiberboard, drywall, gypsum,
gypsum composites, wood, wood composites, plywood, thermoplastics,
plastic composites, resins, metals, metal alloys, metal composites,
and combinations thereof
[0048] In an additional embodiment, sheets of compressed particles
of exfoliated graphite are incorporated into the panel, situated in
contact with the carbon foam core. These graphite sheets can either
be on one side or both sides of the carbon foam core, in between
the outer layers and the carbon foam core. Suitable sheets of
compressed particles of exfoliated graphite (often referred to in
the industry as "flexible graphite") can be produced by
intercalating graphite flakes with a solution containing, e.g., a
mixture of nitric and sulfuric acids, expanding or exfoliating the
flakes by exposure to heat, and then compressing the exfoliated
flakes to form coherent sheets. The production of sheets of
compressed particles of exfoliated graphite is described in, for
instance, U.S. Patent Application Publication No.
US-2005-0079355-A1, the disclosure of which is incorporated herein
by reference.
[0049] By the incorporation of sheets of compressed particles of
exfoliated graphite with the carbon foam core, a superior fire
retardant structure is created. The anisotropic thermal properties
of an compressed exfoliated graphite sheet on one or both opposing
sides of the carbon foam core provide significant improvements in
thermal management.
[0050] The first outer layer 14 and the second outer layer 16 are
connected to the carbon foam core 12 through a bonding or adhesive
material 18. This bonding or adhesive material 18 can include
chemical bonding agents suitable for specific applications ranging
from high temperature conditions to exposure to an acidic
environment. Different chemical bonding materials include
adhesives, glues, cement, and mastic. Optionally, the first outer
layer 14 and second outer layer 16 can be attached to the carbon
foam core 12 through mechanical materials. While this method does
affect the integrity and uniform characteristics of carbon foam
core 12, mechanical connects are available for little cost and are
extremely quick to complete. Various mechanical attaching methods
of attaching both the first outer layer 14 and the second outer
layer 16 to the carbon foam core 12 include but are not limited to
nails, studs, screws, braces, struts, fasteners, staples, and
combinations thereof. Additionally, the first outer layer 14 and
the second outer layer 16 can be compressedly bound to the carbon
foam core through a series of high compression treatments of the
outer layers 14 and 16 to the carbon foam core. While less
permanent than either the mechanical or chemical attachment
options, this attach type introduces no extra chemical compounds or
weakens the structural integrity of carbon foam core 12 as does
either the chemical or mechanical attachment methods.
[0051] First coating 20 and second coating 22 are both optional and
applied to carbon foam core 12 to alter the carbon foam core's 12
properties. Specifically, first coating 20 and second coating 22
can be identical or different, depending upon the conditions and
necessary properties of the carbon foam core 12. For example, first
coating 20 and second coating 22 can both be a coating to improve
the fire retardant properties of the carbon foam core 12.
Additionally, the first coating 20 could be an oxidation resistant
coating where as the second coating 22 could be a fire retardant
coating where one side of panel 10 would be more likely exposed to
an oxidation atmosphere while the other side of panel 10 would have
a greater likelihood of being exposed to fire. Also, first coating
20 and second coating 22 are optionally applied; for many
applications of cold storage panel 10, neither first coating 20 nor
second coating 22 are necessary.
[0052] With carbon foam core 12 as the insulating layer in cold
storage panel 10, panel 10 has an inherent fire retardant/resistant
property. As other insulating materials merely preclude oxygen from
the structural insulating panel's structure, carbon foam core 12 is
extremely resistant to both combustion or charring. Specifically,
carbon foam core 12 is mainly linked carbons with relatively few
other elements present within its foam structure. As such, little
exists for combustion, other than the simple oxidation of the
carbon of carbon foam core 12. For this oxidation to occur,
temperatures have to reach rather extreme temperatures, making
carbon foam core 12 very suitable for applications where fire
retardant structures are required.
[0053] Similarly, carbon foam core 12 is resistant to many
environmental stresses including insects, humidity, and heat.
Carbon foam is an extremely hard substance, lending itself poorly
to insect habitation while its chemical and structural properties
are virtually not altered by a change in humidity. Furthermore,
first outer layer 14 and second outer layer 16 can be selected for
the specific environmental applications to which panel 10 will be
subjected.
[0054] Finally, cold storage panel 10 and its fire retardant
nature, superior strength to density ratio as well as resistance to
chemical degradation make panel 10 suitable for a wide variety of
cold storage applications. These abovementioned applications are
feasible uses of the inventive carbon foam structural insulated
panel yet by no mean include all applications for which this
invention is feasible.
[0055] Accordingly, by the practice of the present invention, cold
storage panels with carbon foam cores, having heretofore
unrecognized characteristics are prepared. These panels with carbon
foam cores exhibit exceptionally high compressive strength to
density ratios, much improved fire retardance and environmental
stability, making them uniquely effective at cold storage
applications, ranging from refrigerators and freezers, to food
lockers and coolers.
[0056] The disclosures of all cited patents and publications
referred to in this application are incorporated herein by
reference.
[0057] The above description is intended to enable the person
skilled in the art to practice the invention. It is not intended to
detail all of the possible variations and modifications that will
become apparent to the skilled worker upon reading the description.
It is intended, however, that all such modifications and variations
be included within the scope of the invention that is defined by
the following claims. The claims are intended to cover the
indicated elements and steps in any arrangement or sequence that is
effective to meet the objectives intended for the invention, unless
the context specifically indicates the contrary.
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