U.S. patent application number 11/796880 was filed with the patent office on 2007-12-06 for load bearing structure with inserts.
Invention is credited to Michel Florentine Jozef Berghmans, Bruce R. Carter, Robert Stoffa.
Application Number | 20070277706 11/796880 |
Document ID | / |
Family ID | 38801784 |
Filed Date | 2007-12-06 |
United States Patent
Application |
20070277706 |
Kind Code |
A1 |
Carter; Bruce R. ; et
al. |
December 6, 2007 |
Load bearing structure with inserts
Abstract
A load-bearing platform that includes an expandable polymer
matrix core and a skin disposed over a bottom side of the core. The
core includes a base and a plurality of legs extending from one
side of the base, the legs having one or more core insert openings
in a bottom surface of the legs. The skin includes a plurality of
legs, each adapted to accept a leg of the core and one or more skin
insert openings corresponding to a core insert opening, where at
least one leg insert per leg is inserted into an insert opening.
The load bearing platform can be used for shipping articles.
Inventors: |
Carter; Bruce R.; (Exeter,
CA) ; Berghmans; Michel Florentine Jozef; (Calgary,
CA) ; Stoffa; Robert; (Cranberry Township,
PA) |
Correspondence
Address: |
NOVA Chemicals Inc.
Westpointe Center, 1550 Coraopolis Heights Road
Moon Township
PA
15108
US
|
Family ID: |
38801784 |
Appl. No.: |
11/796880 |
Filed: |
April 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60809913 |
Jun 1, 2006 |
|
|
|
60844836 |
Sep 15, 2006 |
|
|
|
Current U.S.
Class: |
108/51.3 ;
108/56.3; 108/57.15 |
Current CPC
Class: |
B65D 2519/00034
20130101; B65D 2519/00567 20130101; B65D 2519/00781 20130101; B65D
2519/00059 20130101; B65D 2519/00288 20130101; B65D 19/0028
20130101; B65D 2519/00104 20130101; B65D 2519/00273 20130101; B65D
2519/00338 20130101 |
Class at
Publication: |
108/51.3 ;
108/56.3; 108/57.15 |
International
Class: |
B65D 19/00 20060101
B65D019/00 |
Claims
1. A load-bearing platform comprising an expandable polymer matrix
core and a skin disposed over a bottom side of the core wherein the
core comprises a base and a plurality of legs extending from one
side of the base, the legs having one or more core insert openings
in a bottom surface of the legs, and the skin comprises a plurality
of legs, each adapted to accept a leg of the core and one or more
skin insert openings corresponding to a core insert opening; and
wherein at least one leg insert per leg is inserted into an insert
opening.
2. The load-bearing platform according to claim 1, wherein the
expandable polymer matrix comprises one or more expandable
plastics.
3. The load-bearing platform according to claim 1, wherein the
expandable plastics are one or more selected from the group
consisting of interpolymers of one or more polyolefins and in situ
polymerized vinyl aromatic monomers, expandable polystyrene,
expandable styrenic polymers, expandable polyolefins, rubber
modified styrenic polymers where the styrenic polymer constitutes a
continuous phase and the rubber constitutes a dispersed phase in
the resin, rubber modified styrenic polymers where the rubber
constitutes a continuous phase and the styrenic polymer-constitutes
a dispersed phase in the resin, polyphenylene oxide, and
combinations and blends thereof.
4. The load-bearing platform according to claim 3, wherein the
polyolefins are selected from the group consisting of low density
polyethylene, medium density polyethylene, high density
polyethylene, an ethylene vinyl acetate copolymer, an
ethylene/propylene copolymer, a blend of polyethylene and
polypropylene, a blend of polyethylene and an ethylene/vinyl
acetate copolymer, and a blend of polyethylene and an
ethylene/propylene copolymer, ethylene-butyl acrylate copolymer,
ethylene-methyl methacrylate copolymer and combinations
thereof.
5. The load-bearing platform according to claim 3, wherein the
vinyl aromatic monomers are selected from the group consisting of
styrene, alpha-methylstyrene, ethylstyrene, chlorostyrene,
bromostyrene, vinyltoluene, vinylbenzene, and isopropylxylene and
admixtures thereof.
6. The load-bearing platform according to claim 1, wherein the
expandable polymer matrix comprises a blowing agent and/or
plasticizer.
7. The load-bearing platform according to claim 1, wherein the
expandable polymer matrix comprises polymers selected from the
group consisting of expandable polystyrene, expandable polyolefins,
rubber modified styrenic polymers where the styrenic polymer
constitutes a continuous phase and the rubber constitutes a
dispersed phase in the resin, rubber modified styrenic polymers
where the rubber constitutes a continuous phase and the styrenic
polymer constitutes a dispersed phase in the resin, polyphenylene
oxide, and combinations and blends thereof.
8. The load-bearing platform according to claim 3, wherein the
expandable polymer contains from 25 to 99% based on the weight of
the expandable polymer matrix of interpolymers of a polyolefin and
in situ polymerized vinyl aromatic monomers and from 1 to 75% based
on the weight of the expandable polymer matrix of other expandable
polymers.
9. The load-bearing platform according to claim 1, wherein the load
bearing platform is in the shape of a rectangle and has an edge of
from 1 to 25 cm, a length of from 75 to 150 cm and a width of from
65 to 140 cm.
10. The load-bearing platform according to claim 1 comprising a
layer material applied to a topside of the platform.
11. The load-bearing platform according to claim 1, wherein a
continuous or discontinuous groove or channel is molded or cut into
a surface of a topside of the base such that the groove or channel
follows the perimeter of the topside and a first edge of the groove
or channel is spaced apart from an outer edge of the base.
12. The load-bearing platform according to claim 11 comprising a
plurality of panels adapted to fit into the groove or channel.
13. The load-bearing platform according to claim 12 comprising a
top panel that matches the width and length of the load bearing
structure and includes a groove or channel matching the groove or
channel in the topside and is adapted to accept a top surface of
the panels to form a box or open box structure.
14. The load-bearing platform according to claim 1, wherein the leg
inserts comprise a base having a top surface and bottom surface; a
thickness defined as the distance between top surface and bottom
surface that is larger at a center portion than at an edge of the
base; and two or more fingers extending perpendicular from the top
surface of the base.
15. The load-bearing platform according to claim 14, wherein a
gripping means is included at a terminal end of the fingers.
16. The load-bearing platform according to claim 14, wherein the
gripping means is selected from the group consisting of a shoulder,
knobs, buttons, ribs, teeth, and a collar.
17. The load-bearing platform according to claim 14, wherein the
ratio of widest diameter of terminal ends of the fingers and the
diameter of the insert opening is at least 1.001.
18. The load-bearing platform according to claim 1, wherein the leg
inserts are made of a material selected from the group consisting
of hard plastics, metals, ceramics, composite materials, and
combinations of such materials.
19. The load-bearing platform according to claim 1, wherein the
skin comprises one or more materials selected from the group
consisting of homopolymers and copolymers of styrene, homopolymers
and copolymers of C.sub.2 to C.sub.20 olefins, homopolymers and
copolymers of C.sub.4 to C.sub.20 dienes, polyesters, polyamides,
homopolymers and copolymers of C.sub.2 to C.sub.20 (meth)acrylate
esters, polyetherimides, polycarbonates, polyphenylethers,
polyvinylchlorides, copolymers of styrene, C.sub.4 to C.sub.20
dienes and (meth)acrylonitrile polyurethanes, and combinations
thereof.
20. The load-bearing platform according to claim 18, wherein one or
more materials selected from the group consisting of carbon fibers,
aramid fibers, glass fibers, metal fibers, woven fabric or
structures of the mentioned fibers, fiberglass, carbon black,
graphite, clays, calcium carbonate, titanium dioxide, woven fabric
or structures of the above-referenced fibers, and combinations
thereof are incorporated into the thermoplastic materials.
21. The load-bearing platform according to claim 1, wherein the
skin has a thickness of from 0.1 mm to 1.5 mm.
22. The load-bearing platform according to claim 1, wherein a
device that provides a rolling mechanism is attached to the leg
inserts.
23. A method of shipping articles comprising loading articles onto
a top surface of the load bearing platform according to claim 1.
Description
[0001] This application claims the benefit of priority of U.S.
Provisional Application Ser. No. 60/809,913, filed Jun. 1, 2006,
and 60/844,836, filed Sep. 15, 2006, both entitled "Load Bearing
Structure With Inserts" which are both herein incorporated by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is directed to novel load-bearing
structures, such as pallets, generally used for stacking articles
on for storage and/or shipping.
[0004] 2. Description of the Prior Art
[0005] A shipping pallet is a well known load-bearing, moveable
platform whereon articles are placed for storage and/or shipment.
The pallet usually is loaded with a multiplicity of items, such as
cartons or boxes. The loaded pallet is movable, usually with the
aid of either a pallet truck or a forklift. Generally, pallets are
made from wood.
[0006] The weight of the wood pallet is in the range of from forty
to seventy pounds. Therefore, the weight of cargo shipped on the
wood pallet is reduced by from forty to seventy pounds to provide
for the weight of the wood pallet. This severely limits the amount
of goods that can be shipped, especially by air.
[0007] Further, numerous injuries caused by wood splinters and
nails are frequent occurrences among people who handle wood
pallets. Additionally, disposal of wood pallets is a frequent
concern.
[0008] There has been concern among nations about the use of the
wood pallet causing an import of wood-boring insects, including the
Asian Longhorned Beetle, the Asian Cerambycid Beetle, the Pine Wood
Nematode, the Pine Wilt Nematode and the Anoplophora Glapripwnnis.
Exemplary of damage caused by imported insects is the fate of the
Chestnut Tree in the United States. There was a time when it was
said that a squirrel could cross the United States on Chestnut Tree
limbs without ever touching the ground. Insect infestation has
caused the extinction of the Chestnut Tree in the United
States.
[0009] Efforts to overcome the disadvantages of wood pallets have
lead to molded foam plastic pallets. For example, U.S. Pat. No.
6,786,992 discloses a pallet having an expanded polystyrene core
and a layer of high impact polystyrene covering a portion of the
core.
[0010] U.S. Patent Application Publication No. 2005/0263044
discloses a pallet that includes a shape defining compressible core
member, having at least one surface including a convex feature and
a core member perimeter; and a thermoplastic shell having a shell
interior and a shell edge, where the shell includes a first pliable
thermoplastic sheet having an interior shaped by the convex surface
of the core member and a first sheet edge extending outside of the
core member perimeter, and a second pliable thermoplastic sheet
having a second sheet interior and second sheet edge extending
outside of the core member perimeter.
[0011] Generally, pallets made from plastics, especially foamed
plastics, are not as strong as traditional wood pallets and,
therefore, break under the load-bearing stress applied during use.
Additionally, pallets made of foamed plastics tend to stick to the
floor and/or generally resist sliding when being manipulated with a
forklift truck resulting in the pallet breaking at its weakest
point. The inability of foamed plastic pallets to stand up to these
handling stresses have made them undesirable.
[0012] Therefore, there is a need in the art to provide a
lightweight pallet that can withstand the load-bearing stress of
repeated use and handling for shipping and/or storing articles
traditionally found in wood pallets weight.
SUMMARY OF THE INVENTION
[0013] The present invention is directed to a load-bearing platform
that includes an expandable polymer matrix core and a skin disposed
over a bottom side of the core. The core includes a base and a
plurality of legs extending from one side of the base, the legs
having one or more core insert openings in a bottom surface of the
legs. The skin includes a plurality of legs, each adapted to accept
a leg of the core and one or more skin insert openings
corresponding to a core insert opening, where at least one leg
insert per leg is inserted into an insert opening.
[0014] The present invention also provides a method of shipping
articles that includes loading articles onto a top surface of the
above-described load bearing platform.
DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a top perspective view of a load bearing platform
according to the invention;
[0016] FIG. 2 is a bottom perspective view of a load bearing
platform according to the invention;
[0017] FIG. 3 is a perspective view of a leg insert according to
the invention;
[0018] FIG. 4 is a top plan view of a leg insert according to the
invention;
[0019] FIG. 5 is a side elevation view of a leg insert according to
the invention;
[0020] FIG. 6 is a cross-sectional view of a leg insert according
to the invention;
[0021] FIG. 7 is a perspective view of a leg part of a load bearing
platform and a leg insert according to the invention;
[0022] FIG. 8 is a top perspective view of a load bearing platform
according to the invention;
[0023] FIG. 9 is a bottom perspective view of a load bearing
platform according to the invention;
[0024] FIG. 10 is a bottom plan view of a load bearing platform
according to the invention;
[0025] FIG. 11 is a top perspective view of a skinned load bearing
platform according to the invention; and
[0026] FIG. 12 is a bottom perspective view of a skinned load
bearing platform according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] For the purpose of the description hereinafter, the terms
"upper", "lower", "inner", "outer", "right", "left", "vertical",
"horizontal", "top", "bottom", and derivatives thereof, shall
relate to the invention as oriented in the drawing Figures.
However, it is to be understood that the invention may assume
alternate variations and step sequences except where expressly
specified to the contrary. It is also to be understood that the
specific devices and processes illustrated in the attached drawings
and described in the following specification, is an exemplary
embodiment of the present invention. Hence, specific dimensions and
other physical characteristics related to the embodiment disclosed
herein are not to be considered as limiting the invention. In
describing the embodiments of the present invention, reference will
be made herein to the drawings in which like numerals refer to like
features of the invention.
[0028] Other than in the operating examples or where otherwise
indicated, all numbers or expressions referring to quantities of
ingredients, reaction conditions, etc. used in the specification
and claims are to be understood as modified in all instances by the
term "about". Accordingly, unless indicated to the contrary, the
numerical parameters set forth in the following specification and
attached claims are approximations that can vary depending upon the
desired properties, which the present invention desires to obtain.
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.
[0029] 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 values, however,
inherently contain certain errors necessarily resulting from the
standard deviation found in their respective testing
measurements.
[0030] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between and including the recited minimum value of 1
and the recited maximum value of 10; that is, having a minimum
value equal to or greater than 1 and a maximum value of equal to or
less than 10. Because the disclosed numerical ranges are
continuous, they include every value between the minimum and
maximum values. Unless expressly indicated otherwise, the various
numerical ranges specified in this application are
approximations.
[0031] As used herein, the term "expandable polymer matrix" refers
to a polymeric material in particulate or bead form that is
impregnated with a blowing agent such that when the particulates
and/or beads are placed in a mold and heat is applied thereto,
evaporation of the blowing agent (as described below) effects the
formation of a cellular structure and/or an expanding cellular
structure in the particulates and/or beads and the outer surfaces
of the particulates and/or beads fuse together to form a continuous
mass of polymeric material conforming to the shape of the mold.
[0032] As used herein, the terms "expanded plastics" and "expanded
resin beads" refer to thermoplastic particles that have been
impregnated with a blowing agent, at least some of which is
subsequently removed (as a non-limiting example heated and expanded
followed by evaporation and diffusion out of the bead) in a way
that increases the volume of the particles and accordingly
decreases their bulk density.
[0033] As used herein, the term "thermoplastic" refers to materials
that are capable of softening, fusing, and/or modifying their shape
when heated and of hardening again when cooled.
[0034] As used herein, the term "polymer" is meant to encompass,
without limitation, homopolymers, copolymers and graft
copolymers.
[0035] As used herein, the term "polyolefin" refers to a polymer
prepared from at least one olefinic monomer, such as alpha
unsaturated C.sub.2-C.sub.32 linear or branched alkenes,
non-limiting examples of which include ethylene, propylene,
1-butene, 1-hexene and 1-octene.
[0036] As used herein, the term "polyethylene" refers to and
includes not only a homopolymer of ethylene, but also an ethylene
copolymer containing units of at least 50 mole %, in some cases at
least 70 mole %, and in other cases at least 80 mole % of an
ethylene unit and a corresponding proportion of units from a
monomer copolymerizable with ethylene, and blends containing at
least 50% by weight, in some cases at least 60% by weight, and in
other cases at least 75% by weight of an ethylene homopolymer or
copolymer with another polymer.
[0037] Non-limiting examples of monomers that can be copolymerized
with ethylene include vinyl acetate, vinyl chloride, propylene,
1-butene, 1-hexene, and (meth)acrylic acid and its esters.
[0038] Polymers that can be blended with ethylene homopolymers or
copolymers include any polymer compatible with ethylene
homopolymers or copolymers. Non-limiting examples of polymers that
can be blended with ethylene homopolymers or copolymers include
polypropylene, polybutadiene, polyisoprene, polychloroprene,
chlorinated polyethylene, polyvinyl chloride, styrene/butadiene
copolymers, vinyl acetate/ethylene copolymers,
acrylonitrile/butadiene copolymers, styrene/butadiene/acrylonitrile
copolymers, and vinyl chloride/vinyl acetate copolymer.
[0039] As used herein, the term "styrenic polymers" refers to
homopolymers of styrenic monomers and copolymers of styrenic
monomers and other copolymerizable monomers, where the styrenic
monomers make up at least 50 mole percent of the monomeric units in
the copolymer. Non-limiting examples of styrenic monomers include
styrene, p-methyl styrene, .alpha.-methyl styrene, tertiary butyl
styrene, dimethyl styrene, nuclear brominated or chlorinated
derivatives thereof and combinations thereof. Non-limiting examples
of suitable copolymerizable monomers include 1,3-butadiene,
C.sub.1-C.sub.32 linear, cyclic or branched alkyl (meth)acrylates
(specific non-limiting examples include butyl (meth)acrylate, ethyl
(meth)acrylate, methyl (meth)acrylate, and 2-ethylhexyl
(meth)acrylate), acrylonitrile, vinyl acetate,
alpha-methyl-ethylene, divinyl benzene, maleic anhydride, maleic
acid, fumaric acid, C.sub.1-C.sub.12 linear, branched or cyclic
mono- and di-alkyl esters of maleic acid, C.sub.1-C.sub.12 linear,
branched or cyclic mono- and di-alkyl esters of fumaric acid,
itaconic acid, C.sub.1-C.sub.12 linear, branched or cyclic mono-
and di-alkyl esters of itaconic acid, itaconic anhydride and
combinations thereof.
[0040] As used herein, the terms "(meth)acrylic" and
"(meth)acrylate" are meant to include both acrylic and methacrylic
acid derivatives, such as the corresponding alkyl esters often
referred to as acrylates and (meth)acrylates, which the term
"(meth)acrylate" is meant to encompass.
[0041] As used herein, the term "molding" refers to the shaping of
a pliable material to assume a new desired shape. Molding can
involve the use of specific molding tools such as male and female
molding tools, sculptured platens, and the like. It can also
include the use of specifically shaped core members including
compressible core members that are used to impart a desired shape
to at least a portion of a thermoplastic material.
[0042] As used herein, the term "expansion factor" refers to the
volume a given weight of expanded polymer bead occupies, typically
expressed as cc/g.
[0043] The present invention provides a load-bearing platform that
includes a base, a plurality of legs extending from one side of the
base and one or more leg inserts inserted into a bottom surface of
one or more of the legs.
[0044] The present load-bearing platform is made from an expandable
polymer matrix, which can include one or more expandable
plastics.
[0045] Suitable expandable plastics include, but are not limited to
interpolymers of a polyolefin and in situ polymerized vinyl
aromatic monomers, expandable polystyrene (EPS), expandable
styrenic polymers, expandable polyolefins, rubber modified styrenic
polymers where the styrenic polymer constitutes a continuous phase
and the rubber constitutes a dispersed phase in the resin, rubber
modified styrenic polymers where the rubber constitutes a
continuous phase and the styrenic polymer constitutes a dispersed
phase in the resin as described in copending U.S. Patent
Application Publication No. 2006/0276558, the relevant portions of
which are herein incorporated by reference, polyphenylene oxide,
and combinations and blends thereof.
[0046] In an embodiment of the invention, the expandable plastics
can include one or more polymers selected from homopolymers of
vinyl aromatic monomers; copolymers of at least one vinyl aromatic
monomer with one or more of divinylbenzene, conjugated dienes,
alkyl methacrylates, alkyl acrylates, acrylonitrile, and/or maleic
anhydride; polyolefins; polycarbonates; polyesters; polyamides;
natural rubbers; synthetic rubbers; and combinations thereof.
[0047] In a particular embodiment of the invention, the expandable
plastics include thermoplastic homopolymers or copolymers selected
from homopolymers derived from vinyl aromatic monomers including
styrene, isopropylstyrene, alpha-methylstyrene, nuclear
methylstyrenes, chlorostyrene, tert-butylstyrene, and the like, as
well as copolymers prepared by the copolymerization of at least one
vinyl aromatic monomer as described above with one or more other
monomers, non-limiting examples being divinylbenzene, conjugated
dienes (non-limiting examples being butadiene, isoprene, 1,3- and
2,4-hexadiene), alkyl methacrylates, alkyl acrylates,
acrylonitrile, and maleic anhydride, wherein the vinyl aromatic
monomer is present in at least 50% by weight of the copolymer. In
an embodiment of the invention, styrenic polymers are used,
particularly polystyrene. However, other suitable polymers can be
used, such as polyolefins (e.g. polyethylene, polypropylene),
polycarbonates, polyphenylene oxides, and mixtures thereof.
[0048] In a more particular embodiment of the invention, the
expandable plastics include expandable polystyrene (EPS) particles.
These particles can be in the form of beads, granules, or other
particles convenient for the expansion and molding operations.
[0049] In the present invention, the expandable plastics can be
particles polymerized in a suspension process, which are
essentially spherical resin beads useful for making expandable
polymer particles. However, polymers derived from solution and bulk
polymerization techniques that are extruded and cut into particle
sized resin bead sections can also be used.
[0050] In an embodiment of the invention, resin beads (unexpanded)
of expandable plastics containing any of polymers or polymer
compositions described herein can have a particle size of at least
0.2, in some situations at least 0.33, in some cases at least 0.35,
in other cases at least 0.4, in some instances at least 0.45 and in
other instances at least 0.5 mm. Also, the resin beads can have a
particle size of up to 3, in some instances up to 2, in other
instances up to 2.5, in some cases up to 2.25, in other cases up to
2, in some situations up to 1.5 and in other situations up to 1 mm.
The resin beads used in this embodiment can be any value or can
range between any of the values recited above.
[0051] The expandable plastic particles or resin beads can
optionally be impregnated using any conventional method with a
suitable blowing agent. As a non-limiting example, the impregnation
can be achieved by adding the blowing agent to the aqueous
suspension during the polymerization of the polymer, or
alternatively by re-suspending the polymer particles in an aqueous
medium and then incorporating the blowing agent as taught in U.S.
Pat. No. 2,983,692. Any gaseous material or material which will
produce gases on heating can be used as the blowing agent.
Conventional blowing agents include aliphatic hydrocarbons
containing 4 to 6 carbon atoms in the molecule, such as butanes,
pentanes, hexanes, and the halogenated hydrocarbons, e.g., CFC's
and HCFC's, which boil at a temperature below the softening point
of the polymer chosen. Mixtures of these aliphatic hydrocarbon
blowing agents can also be used.
[0052] Alternatively, water can be blended with these aliphatic
hydrocarbon blowing agents or water can be used as the sole blowing
agent as taught in U.S. Pat. Nos. 6,127,439; 6,160,027; and
6,242,540, In these patents, water-retaining agents are used. The
weight percentage of water for use as the blowing agent can range
from 1 to 20%. The text of U.S. Pat. Nos. 6,127,439, 6,160,027 and
6,242,540 are incorporated herein by reference.
[0053] The impregnated resin beads are optionally expanded to a
bulk density of at least 0.5 lb/ft.sup.3 (0.008 g/cc), in some
cases at least 1.25 lb/ft.sup.3 (0.02 g/cc), in other cases at
least 1.5 lb/ft.sup.3 (0.024 g/cc), in some situations at least
1.75 lb/ft.sup.3 (0.028 g/cc), in some circumstances at least 2
lb/ft.sup.3 (0.032 g/cc), in other circumstances at least 3
lb/ft.sup.3 (0.048 g/cc), and in particular circumstances at least
3.25 lb/ft.sup.3 (0.052 g/cc) or 3.5 lb/ft.sup.3 (0.056 g/cc). When
non-expanded resin beads are used, higher bulk density beads can be
used. As such, the bulk density can be as high as 40 lb/ft.sup.3
(0.64 g/cc). The bulk density of the polymer particles can be any
value or range between any of the values recited above.
[0054] The expansion step is conventionally carried out by heating
the impregnated beads via any conventional heating medium, such as
steam, hot air, hot water, or radiant heat. One generally accepted
method for accomplishing the pre-expansion of impregnated
thermoplastic particles is taught in U.S. Pat. No. 3,023,175.
[0055] The impregnated resin beads can be foamed cellular polymer
particles as taught in U.S. Patent Application Publication No.
2002-0117769 A1, the teachings of which are incorporated herein by
reference. The foamed cellular particles can be polystyrene that
are expanded and contain a volatile blowing agent at a level of
less than 14 wt. %, in some situations less than 6 wt. %, in some
cases ranging from about 2 wt. % to about 5 wt. %, and in other
cases ranging from about 2.5 wt. % to about 3.5 wt. % based on the
weight of the polymer.
[0056] The expandable polymer matrix can include an interpolymer of
a polyolefin and in situ polymerized vinyl aromatic monomers and
optionally other expandable polymers.
[0057] In the embodiments of the invention, the interpolymer of a
polyolefin and in situ polymerized vinyl aromatic monomers is one
or more of those described in U.S. Pat. Nos. 3,959,189; 4,168,353;
4,303,756; 4,303,757 and 6,908,949, the relevant portions of which
are herein incorporated by reference. A non-limiting example of
such interpolymers that can be used in the present invention
include those available under the trade name ARCEL.RTM., available
from NOVA Chemicals Inc., Pittsburgh, Pa. and PIOCELAN.RTM.,
available from Sekisui Plastics Co., Ltd., Tokyo, Japan.
[0058] In the embodiments of the invention, the interpolymer of a
polyolefin and in situ polymerized vinyl aromatic monomers is a
particle or resin bead, which is subsequently processed to form the
load bearing structures according to the present invention. The
interpolymer particles used in the invention include a polyolefin
and an in situ polymerized vinyl aromatic resin that form an
interpenetrating network of polyolefin and vinyl aromatic resin
particles. The interpolymer particles are impregnated with a
blowing agent and optionally, a plasticizer.
[0059] Such interpolymer particles can be obtained by processes
that include suspending polyolefin particles and vinyl aromatic
monomer or monomer mixtures in an aqueous suspension and
polymerizing the monomer or monomer mixtures inside the polyolefin
particles. Non-limiting examples of such processes are disclosed in
U.S. Pat. Nos. 3,959,189, 4,168,353 and 6,908,949.
[0060] In an embodiment of the invention, the polyolefin includes
one or more polyethylene resins selected from low-, medium-, and
high-density polyethylene, an ethylene vinyl acetate copolymer, an
ethylene/propylene copolymer, a blend of polyethylene and
polypropylene, a blend of polyethylene and an ethylene/vinyl
acetate copolymer, and a blend of polyethylene and an
ethylene/propylene copolymer. Ethylene-butyl acrylate copolymer and
ethylene-methyl methacrylate copolymer can also be used.
[0061] The amount of polyolefin in the interpolymer resin particles
of the invention can be at least 20%, in some cases at least 25%,
and in other cases at least 30% and can be up to 80%, in some cases
up to 70%, in other cases up to 60% and in some instances up to
55%, by weight based on the weight of the interpolymer resin
particles. The amount of polyolefin in the interpolymer resin
particles can be any value or range between any of the values
recited above.
[0062] The amount of polymerized vinyl aromatic resin in the
interpolymer resin particles of the invention ranges can be at
least 20%, in some cases at least 30%, in other cases at least 40%,
and in some instances at least 45%, and can be up to 80%, in some
cases up to 75%, and in other cases up to 70%, by weight based on
the weight of the interpolymer resin particles. The amount of
polymerized vinyl aromatic resin in the interpolymer resin
particles can be any value or range between any of the values
recited above.
[0063] The vinyl aromatic resin can be made up of polymerized vinyl
aromatic monomers or the resin can be a copolymer containing
monomeric units from vinyl aromatic monomers and copolymerizable
comonomers. Non-limiting examples of vinyl aromatic monomers that
can be used in the invention include styrene, alpha-methylstyrene,
ethylstyrene, chlorostyrene, bromostyrene, vinyltoluene,
vinylbenzene, and isopropylxylene. These monomers may be used
either alone or in admixture.
[0064] Non-limiting examples of copolymerizable comonomers include
1,3-butadiene, C.sub.1-C.sub.32 linear, cyclic or branched alkyl
(meth)acrylates (specific non-limiting examples include butyl
(meth)acrylate, ethyl (meth)acrylate and 2-ethylhexyl
(meth)acrylate), acrylonitrile, vinyl acetate,
alpha-methylethylene, divinyl benzene, maleic anhydride, itaconic
anhydride, dimethyl maleate and diethyl maleate.
[0065] Non-limiting examples of vinyl aromatic copolymers, that can
be used in the invention, include those disclosed in U.S. Pat. No.
4,049,594. Specific non-limiting examples of suitable vinyl
aromatic copolymers include copolymers containing repeat units from
polymerizing styrene and repeat units from polymerizing one or
monomers selected from 1,3-butadiene, C.sub.1-C.sub.32 linear,
cyclic or branched alkyl (meth)acrylates (specific non-limiting
examples including butyl (meth)acrylate, ethyl (meth)acrylate and
2-ethylhexyl (meth)acrylate), acrylonitrile, vinyl acetate,
alpha-methylethylene, divinyl benzene, maleic anhydride, itaconic
anhydride, dimethyl maleate and diethyl maleate.
[0066] In particular embodiments of the invention, the vinyl
aromatic resin includes polystyrene or styrene-butyl acrylate
copolymers.
[0067] In general, the interpolymer resin particles are formed as
follows: The polyolefin particles are dispersed in an aqueous
medium prepared by adding 0.01 to 5%, in some cases 2 to 3%, by
weight based on the weight of the water of a suspending agent such
as water soluble high molecular weight materials, e.g., polyvinyl
alcohol or methyl cellulose or slightly water soluble inorganic
materials, e.g., calcium phosphate or magnesium pyrophosphate and
soap, such as sodium dodecyl benzene sulfonate, and the vinyl
aromatic monomers are added to the suspension and polymerized
inside the polyolefin particles.
[0068] Any conventionally known and commonly used suspending agents
for polymerization of vinyl aromatic monomers can be employed.
These agents are well known in the art and can be freely selected
by one skilled in the art. Initially, the water is in an amount
generally from 0.7 to 5, preferably 3 to 5 times that of the
starting polyolefin particles employed in the aqueous suspension,
on a weight basis, and gradually the ratio of the polymer particles
to the water may reach around 1:1.
[0069] The polymerization of the vinyl aromatic monomers, which is
absorbed in the polyolefin particles, is carried out using
initiators.
[0070] The initiators suitable for suspension polymerization of the
vinyl aromatic monomers are generally used in an amount of about
0.05 to 2 percent by weight, in some cases 0.1 to 1 percent by
weight, based on the weight of the vinyl aromatic monomer.
Non-limiting examples of suitable initiators include organic
peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl
perbenzoate and t-butyl perpivalate and azo compounds such as
azobisisobutylonitrile and azobisdimethylvaleronitrile.
[0071] These initiators can be used alone or two or more initiators
can be used in combination. In many cases, the initiators are
dissolved in the vinyl aromatic monomers, which are to be absorbed
in the polyolefin particles. In other cases, the initiator can be
dissolved in a solvent, such as toluene, benzene, and
1,2-dichloropropane.
[0072] When the in situ polymerization of the vinyl aromatic
monomers is completed, the polymerized vinyl aromatic resin is
uniformly dispersed inside the polyolefin particles.
[0073] In many cases, the polyolefin particles are cross-linked.
The cross-linking can be accomplished simultaneously with the
polymerization of the vinyl aromatic monomer in the polyolefin
particles, and before impregnation of the blowing agent and/or
plasticizer. For this purpose, cross-linking agents are used. Such
cross-linking agents include, but are not limited to
di-t-butyl-peroxide, t-butyl-cumylperoxide, dicumyl-peroxide,
.alpha., .alpha.-bis-(t-butylperoxy)-p-diisopropylbenzene,
2,5-dimethyl-2,5-di-(t-butylperoxy)-hexyne-3,2,5-dimethyl-2,5-di-(benzoyl-
peroxy)-hexane and t-butyl-peroxyisopropyl-carbonate. These
cross-linking agents are absorbed in the polyolefin particles
together with the vinyl aromatic monomers by dissolving the
cross-linking agent in an amount of about 0.1 to 2 weight % and in
some cases 0.5 to 1 weight %, based on the weight of the polyolefin
particles suspended in water. Further details of the cross-linking
agents and the manner for absorbing the cross-linking agents into
the polyolefin particles are provided in U.S. Pat. No.
3,959,189.
[0074] In an embodiment of the invention, the interpolymer of a
polyolefin and in situ polymerized vinyl aromatic monomers includes
a rubber modified styrenic polymers where the rubber constitutes a
continuous phase and the styrenic polymer constitutes a dispersed
phase in the resin as described in copending U.S. Patent
Application Publication No. 2006/0276558 the relevant portions of
which are herein incorporated by reference.
[0075] The resulting expandable polymer matrix can be used as raw
materials in producing foamed articles. The blowing agent and/or
plasticizer are introduced into the expandable polymer matrix resin
particles to form foamable or expandable particles or resin beads,
which in turn, are used to mold foamed articles.
[0076] The blowing agent should have a boiling point lower than the
softening point of the polyolefin and should be gaseous or liquid
at room temperature (about 20 to 30.degree. C.) and normal pressure
(about atmospheric). Blowing agents are well known in the art and
generally have boiling points ranging from -42.degree. C. to
80.degree. C., more generally, from -10.degree. C. to 36.degree. C.
Suitable hydrocarbon blowing agents include, but are not limited to
aliphatic hydrocarbons such as n-propane, n-butane, iso-butane,
n-pentane, iso-pentane, n-hexane, and neopentane, cycloaliphatic
hydrocarbons such as cyclobutane and cyclopentane, and halogenated
hydrocarbons such as methyl chloride, ethyl chloride, methylene
chloride, trichlorofluoromethane, dischlorofluoromethane,
dichlorodifluormethane, chlorodifluoromethane and
dichloroetetrafluoro-ethane, etc. These blowing agents can be used
alone or as mixtures. If n-butane, ethyl chloride, and
dichlorotetrafluoro-ethane, which are gaseous at room temperature
and normal pressure, are used as a mixture, it is possible to
achieve foaming to a low bulk density. Specific types of volatile
blowing agents are taught in U.S. Pat. No. 3,959,180. In particular
embodiments of the invention, the blowing agent is selected from
n-pentane, iso-pentane, neopentane, cylcopentane, and mixtures
thereof.
[0077] The amount of the blowing agent ranges from about 1.5% to
about 20% by weight, in some cases about 1.5% to 15% by weight, and
in other cases from 5% to 15% by weight, based on the weight of the
expandable polymer matrix.
[0078] A plasticizer can be used in combination with the blowing
agent and as stated herein above and acts as a blowing aid in the
invention.
[0079] Suitable plasticizers include, but are not limited to
benzene, toluene, limonene, linear, branched or cyclic C.sub.5 to
C.sub.20 alkanes, white oil, linear, branched or cyclic C.sub.1 to
C.sub.20 dialkylphthalates, styrene, oligomers of styrene,
oligomers of (meth)acrylates having a glass transition temperature
less than polystyrene, and combinations thereof.
[0080] In a particular embodiment of the invention, the plasticizer
includes limonene, a mono-terpene hydrocarbon existing widely in
the plant world. The known types are d-limonene, l-limonene, and
dl-limonene. D-limonene is contained in the skin of citrus fruits
and is used in food additives as a fragrant agent; its boiling
point is about 176.degree. C.; and its flammability is low.
D-limonene is a colorless liquid, has a pleasant orange-like aroma,
is approved as a food additive, and is widely used as a raw
material of perfume. Limonene is not a hazardous air pollutant.
[0081] The amount of plasticizer can range from about 0.1 to 5
parts and in some cases from about 0.1 to about 1 part by weight
per 100 parts by weight of the expandable polymer matrix.
[0082] In embodiments of the invention, the interpolymer particles
can be produced as follows: In a first reactor, the polyolefin
particles are suspended in an aqueous medium containing a
dispersing agent. The dispersing agent can be polyvinyl alcohol,
methylcellulose, calcium phosphate, magnesium pyrophosphate,
calcium carbonate, tricalcium phosphate, etc. The amount of
dispersing agent employed can be from 0.01 to 5% by weight based on
the amount of water. A surfactant can be added to the aqueous
medium. Generally, the surfactant is used to lower the surface
tension of the suspension and helps to emulsify the water/vinyl
aromatic monomer in mixture in the initiator and wax mixes, if
used. Suitable waxes include polyethylene waxes and ethylene
bistearamide. The aqueous medium is generally heated to a
temperature at which the vinyl aromatic monomers can be
polymerized, i.e., from about 60.degree. C. to about 120.degree. C.
over a period of time, for example, 12 to 20 hours. Over this 12 to
20 hour period, the vinyl aromatic monomers, the vinyl aromatic
polymerization initiator, and the cross-linking agent are added to
the resulting suspension containing the polyolefin particles, which
are dispersed in the aqueous medium. These materials may be added
all at one time, or gradually in individual portions.
[0083] The interpolymer particles are acidified, dewatered,
screened, and subsequently charged to a second reactor where the
particles are impregnated with the blowing agent and/or
plasticizer.
[0084] The impregnation step can be carried out by suspending the
interpolymer particles in an aqueous medium, adding the blowing
agent and/or plasticizer to the resulting suspension, and stirring
at a temperature of, preferably, about 40.degree. C. degrees to
80.degree. C. The blowing agent and/or plasticizer can be blended
together and then added to the interpolymer particles or can be
added to the interpolymer particles separately.
[0085] Alternatively, the blowing agent and/or plasticizer can be
added to the first reactor during or after the polymerization
process.
[0086] The above processes describe a wet process for impregnation
of the interpolymer particles. Alternatively, the interpolymer
particles can be impregnated via an anhydrous process similar to
that taught in Column 4, lines 20-36 of U.S. Pat. No.
4,429,059.
[0087] In an embodiment of the invention, the blowing agent can be
dosed to the expandable polymer matrix in an extruder to produce
resin pellets or beads. The extruder acts to mix the blowing agent
into the expandable polymer matrix prior to extruding a strand of
the mixture. The strand can be cut into bead or pellet lengths
using an appropriate device, a non-limiting example being an
underwater face cutter.
[0088] The particles and/or beads of the expandable polymer matrix
according to the invention can also contain other additives known
in the art, non-limiting examples including anti-static additives;
flame retardants; colorants or dyes; filler materials and
combinations thereof. Other additives can also include chain
transfer agents, non-limiting examples including C.sub.2-15 alkyl
mercaptans, such as n-dodecyl mercaptan, t-dodecyl mercaptan,
t-butyl mercaptan and n-butyl mercaptan, and other agents such as
pentaphenyl ethane and the dimer of alpha-methyl styrene. Other
additives can further include nucleating agents, non-limiting
examples including polyolefin waxes, i.e., polyethylene waxes.
[0089] The expandable polymer matrix can include interpolymers of a
polyolefin and in situ polymerized vinyl aromatic monomers and
optionally other expandable polymers. The other expandable polymers
include those polymers that can provide desirable properties to the
load bearing platform of the invention and that are compatible with
the interpolymers of a polyolefin and in situ polymerized vinyl
aromatic monomers. Non-limiting examples of other expandable
polymers that can be used in the present invention include
expandable polystyrene (EPS), expandable polyolefins, rubber
modified styrenic polymers where the styrenic polymer constitutes a
continuous phase and the rubber constitutes a dispersed phase in
the resin, rubber modified styrenic polymers where the rubber
constitutes a continuous phase and the styrenic polymer constitutes
a dispersed phase in the resin as described in copending U.S.
Patent Application publication No. 2006/0276558 the relevant
portions of which are herein incorporated by reference,
polyphenylene oxide, and combinations and blends thereof.
[0090] The expandable polymer matrix can contain 100% interpolymers
of a polyolefin and in situ polymerized vinyl aromatic monomers,
but can also contain up to 99%, in some cases up to 95%, in other
cases up to 90%, in some instances up to 80% and in other instances
up to 75% based on the weight of the expandable polymer matrix of
interpolymers of a polyolefin and in situ polymerized vinyl
aromatic monomers. Also, the expandable polymer matrix can contain
at least 25%, in some cases at least 30%, in other cases at least
40% and in some instances at least 50% based on the weight of the
expandable polymer matrix of interpolymers of a polyolefin and in
situ polymerized vinyl aromatic monomers. The amount of
interpolymers of a polyolefin and in situ polymerized vinyl
aromatic monomers in the expandable polymer matrix can be any value
or range between any of the values recited above.
[0091] When other expandable polymers are included in the
expandable polymer matrix, the other expandable polymers can be
present at a level of at least 1%, in some cases at least 5%, in
other cases at least 10%, in some instances at least 20% and in
other instances at least 25% based on the weight of the expandable
polymer matrix. Also, the other expandable polymers can be present
in the expandable polymer matrix at a level of up to 75%, in some
cases up to 70%, in other cases up to 60% and in some instances up
to 50% based on the weight of the expandable polymer matrix. The
other expandable polymers can be included in the expandable polymer
matrix at any level or range between any of the values recited
above.
[0092] An embodiment of the load bearing structure according to the
invention is shown in FIGS. 1 and 2, where a load bearing structure
8 includes an expanded polymer matrix core 10, which is in the
general shape of a rectangular slab with an edge 12 that has a
width 14 which can be from 1 to 25 cm, in some cases from 2 to 20
cm and in other cases from 2.5 to 15 cm. Core 10 has a topside 16
that can be from 75 to 150 cm, in some cases from 90 to 140 cm and
in other cases from 100 to 130 cm long and from 65 to 140 cm, in
some cases from 80 to 130 cm and in other cases from 90 to 120 cm
wide. A bottom side 18 of core 10 includes legs 20-28 from 8 to 15
cm, in some cases from 9 to 13 cm long extending from bottom side
10.
[0093] Legs 20-28 and bottom side 18 define spaces 42, 44, 46, and
48 proximate to edge 12. Spaces 42, 44, 46, 48 separate legs 26-28,
legs 20, 23, 26, legs 20-22 and legs 22, 25, 28, respectively, from
the edge 12.
[0094] In an embodiment of the invention, spaces 42, 44, 46, 48 are
adapted to receive the tongues of a forklift truck. As a
non-limiting example, a first tongue of a forklift can be placed
under and along the length of bottom side 18 between leg 20 and leg
23, leg 21 and leg 24 and/or between leg 22 and leg 25 and a second
tongue of a forklift can be placed under and along the length of
bottom side 18 between leg 26 and leg 23, leg 27 and leg 24 and/or
between leg 28 and leg 25. When the forklift truck lifts the first
and second tongues, a surface of each tongue contacts the surface
of bottom side 18 and acts to lift load bearing structure 8 and any
articles stacked on topside 16.
[0095] Because core 10 is made from the above-described expanded
polymer matrix, it has sufficient structural strength to be used as
a load bearing platform.
[0096] Leg inserts 50 are inserted into openings in legs 20-28. Leg
inserts 50 have a raised portion and are made of a material that
allows load bearing platform 8 to slide across surfaces when being
moved and otherwise positioned using, as a non-limiting example, a
forklift truck.
[0097] Leg inserts 50 can be made of any material that allows load
bearing platform to move relatively easily across surfaces when
being handled in ways that are typical for pallets and other load
bearing platforms. As such, leg inserts 50 can be made of, as
non-limiting examples, hard plastics, metals, ceramics, composite
materials, and combinations of such materials and the like.
[0098] Suitable metals include, but are not limited to, aluminum,
steel, stainless steel, tungsten, molybdenum, iron and alloys and
combinations of such metals. In a particular embodiment of the
invention, leg inserts 50 are made of a light gauge metal.
[0099] Suitable hard plastics include, but are not limited to
reinforced thermoplastics, thermoset resins, and reinforced
thermoset resins. Thermoplastics include polymers made up of
materials that can be repeatedly softened by heating and hardened
again on cooling. Suitable thermoplastic polymers include, but are
not limited to homopolymers and copolymers of styrene, homopolymers
and copolymers of C.sub.2 to C.sub.20 olefins, C.sub.4 to C.sub.20
dienes, polyesters, polyamides, homopolymers and copolymers of
C.sub.2 to C.sub.20 (meth)acrylate esters, polyetherimides,
polycarbonates, polyphenylethers, polyvinylchlorides,
polyurethanes, and combinations thereof.
[0100] Suitable thermoset resins are resins that when heated to
their cure point, undergo a chemical cross-linking reaction causing
them to solidify and hold their shape rigidly, even at elevated
temperatures. Suitable thermoset resins include, but are not
limited to alkyd resins, epoxy resins, diallyl phthalate resins,
melamine resins, phenolic resins, polyester resins, urethane
resins, and urea, which can be crosslinked by reaction, as
non-limiting examples, with diols, triols, polyols, and/or
formaldehyde.
[0101] Reinforcing materials and/or fillers that can be
incorporated into the thermoplastics and/or thermoset resins
include, but are not limited to carbon fibers, aramid fibers, glass
fibers, metal fibers, woven fabric or structures of the mentioned
fibers, fiberglass, carbon black, graphite, clays, calcium
carbonate, titanium dioxide, woven fabric or structures of the
above-referenced fibers, and combinations thereof.
[0102] The thermoplastics and thermoset resins can optionally
include other additives, as non-limiting examples, ultraviolet (UV)
stabilizers, heat stabilizers, flame retardants, structural
enhancements, biocides, and combinations thereof.
[0103] In some embodiments of the invention, a wheel or other
suitable device that provides a rolling mechanism is mounted on,
molded into, or otherwise attached to inserts 50. In this
embodiment of the invention, load bearing platform 8 is able to
roll along a surface to provide, in some cases, easier
manipulation, either by hand, forklift, or other method, of a
loaded load bearing platform according to the invention. In
particular embodiments of the invention, inserts 50 are adapted to
be removable to prevent movement during transport. In other
embodiments, the wheel or other rolling device is equipped with a
braking mechanism that can be set to minimize movement of load
bearing platform 8 during transport.
[0104] In order to provide a desirable surface finish and/or
texture and/or to minimize wear and tear from repeated use, a
suitable layer material can be applied to topside 16 and optionally
edge 12.
[0105] Suitable layer materials that can be applied include rubber
modified styrenic polymers, polyamides, such as nylon,
polypropylene, polyethylene, and combinations thereof. Non-limiting
examples of rubber modified styrenic polymers that can be used
include the Dylark.RTM. and Zylar.RTM. resins available from NOVA
Chemicals Inc., Pittsburgh, Pa.
[0106] The density of the expanded polymer matrix in core 10 can be
at least 5, in some cases at least 10 and in other cases at least
15 kg/m.sup.3 and can be up to 40, in some cases up to 35 and in
other cases up to 30 kg/m.sup.3.
[0107] In embodiments of the invention, the density of the expanded
polymer matrix in core 10 corresponding to the portion's proximate
spaces 42, 44, 46, 48 is higher than the density of the expanded
polymer matrix in the remainder of core 10. This feature aids in
preventing stress breakage at the thinnest portions of load bearing
structure 8.
[0108] The load bearing structure can be prepared by heating beads
of the expandable polymer matrix using a heating medium such as
steam. Depending on the desired density in any portion of the load
bearing structure, the beads are expanded to an expansion ratio
(the ratio of expanded bead volume/initial bead volume) of from 5
to 100, in some cases from 10 to 90, in other cases from 20 to 80,
in some instances from 30 to 75 and in other instances from 40 to
70.
[0109] The beads of the expandable polymer matrix according to the
invention can be formed into a load bearing structure of a desired
configuration by pre-expanding the beads and further expanding and
shaping them in a mold cavity. The resulting load bearing structure
has superior thermal stability, chemical resistance (e.g., oil
resistance), and flexural strength compared to EPS pallets.
[0110] In an embodiment of the invention (not shown), a groove or
channel can be molded or cut into the surface of topside 16 such
that the groove or channel follows the perimeter of topside 16 and
a first edge of the groove or channel is spaced apart from edge 12.
The spacing of the groove or channel from edge 12 can be at least 1
cm, in some cases at least 2 cm and can be up to 10 cm, in some
cases up to 8 cm. The groove or channel can be continuous or
discontinuous.
[0111] In a particular embodiment of the invention, the groove or
channel has a width and depth adapted to receive a foam panel. The
foam panel can form an angle or arc to conform to a corner section
of topside 16 directly above a portion of leg 20, 22, 28 and/or 26.
Alternatively, the foam panel can extend along the sides of topside
16 beginning above leg 20 and terminating above leg 22, beginning
above leg 22 and terminating above leg 28, beginning above leg 28
and terminating above leg 26, and/or beginning above leg 26 and
terminating above leg 20. The length of the panels will conform to
the dimensions of load bearing platform 8 as described above. The
height of the panels can be at least 5 cm, in some cases at least
10 cm and in other cases at least 15 cm and can be up to 450 cm, in
some cases up to 400 cm, in other cases up to 350 cm and in some
instances up to 310 cm. The height of the panels can be any value
or range between any of the values recited above.
[0112] In a further embodiment, a top panel can be included that
roughly matches the width and length of load bearing structure 8.
The top panel includes a groove or channel matching the groove or
channel in topside 16 and is adapted to receive a top surface of
the panels.
[0113] When assembled, the load bearing structure, panels and top
panel form a box or open-box structure. Buckles or appropriate
fasteners can be used to secure the panels and structure together.
Alternatively, shrink wrap, duct tape, rope, string or other
suitable binding materials can be applied around the outside
perimeter of the box or open-box structure to secure the parts in
position.
[0114] In an embodiment of the invention, the top panel can be a
load bearing structure 8 that includes a groove or channel that
passes along a corresponding bottom surface of legs 20, 21, 22, 25,
28, 27, 26, and/or 23.
[0115] In another embodiment of the invention, the panels and top
panels are made from the expandable polymer matrix described
herein.
[0116] In other embodiments of the invention, the panels and top
panels are made of one or more other expandable polymers as
described above.
[0117] The panels and/or top panels prevent articles placed or
stacked on topside 16 from sliding or otherwise leaving the surface
of topside 16 when load bearing structure 8 is moved.
[0118] Embodiments of the leg inserts according to the invention
are shown in FIGS. 3-6. Leg insert 100 includes base 102 that has a
top surface 104 and bottom surface 106. The thickness of base 102,
defined as the distance between top surface 104 and bottom surface
106, is generally larger at center portion 108 than at edge 110.
Two or more or a plurality of fingers 112 extend generally
perpendicularly from top surface 104. Terminal end 114 of fingers
112 includes a gripping means 116 for holding leg insert 100 in an
insert opening in a leg of a load bearing platform. Gripping means
116 can be selected from a shoulder (shown), knobs, buttons, ribs,
teeth, a collar or other similar devise for applying pressure
against the inner wall of an insert opening in a leg of a load
bearing platform. The widest diameter 120 of the terminal ends 114
of fingers 112 are typically equal to or slightly larger than the
diameter of the insert opening in a leg of a load bearing platform.
Generally, when leg insert 100 is inserted into an insert opening
in a leg of a load bearing platform, terminal ends 114 are movable
and bend inward to facilitate insertion of leg insert 100 into an
insert opening in a leg of a load bearing platform. Once inserted,
fingers 112 attempt to return to their original configuration and
provide pressure against the inner wall of the insert opening,
which acts to hold leg insert 100 in place.
[0119] Referring to FIG. 7, leg insert 50 can be inserted into leg
insert opening 144 by pushing it into opening 144 until terminal
end 114 contacts bottom 148 of opening 144. When this is
accomplished, gripping means 116 presses against inner wall 146 of
opening 144. As shown, opening 144 is in a top surface 142 and
extends into leg 140 of load bearing platform 130. Leg 140 extends
from top surface 132 of load bearing platform 130.
[0120] In a particular embodiment of the invention, the ratio of
widest diameter 120 to the diameter 160 of insert opening 144 is at
least 1, in some cases at least 1.001, in other cases at least
1.01, in some cases at least 1.025 and in other cases at least
1.05.
[0121] In some embodiments of the invention, a wheel or other
suitable device that provides a rolling mechanism is mounted on,
molded into, or otherwise attached to inserts 50 as described
above. Another embodiment of the load bearing structure according
to the invention is shown in FIGS. 8 and 9, where a load bearing
structure 200 includes an expanded polymer matrix core 210, which
is in the general shape of a rectangular slab with an edge 212 that
has a width 214 which can be from 1 to 25 cm, in some cases from 2
to 20 cm and in other cases from 2.5 to 15 cm. Core 210 has a
topside 216 that can be from 75 to 150 cm, in some cases from 90 to
140 cm and in other cases from 100 to 130 cm long and from 65 to
140 cm, in some cases from 80 to 130 cm and in other cases from 90
to 120 cm wide. A bottom side 218 of core 210 includes legs 220-236
from 8 to 15 cm, in some cases from 9 to 13 cm long extending from
bottom side 10.
[0122] Legs 220-236 and bottom side 218 define spaces 242, 244,
246, and 248 proximate to edge 12. Spaces 242, 244, 246, 248
separate legs 220, 226, and 232, legs 220, 222, and 224, legs 224,
230, and 236 and legs 232, 234, and 236, respectively.
[0123] In an embodiment of the invention, spaces 242, 244, 246, 248
are adapted to receive the tongues of a forklift truck. As a
non-limiting example, a first tongue of a forklift can be placed
under and along the length of bottom side 218 between leg 220 and
leg 226 and between leg 220 and leg 222 and/or between leg 232 and
leg 234 and a second tongue of a forklift can be placed under and
along the length of bottom side 18 between leg 226 and leg 232, leg
222 and leg 224 and/or between leg 234 and leg 236. When the
forklift truck lifts the first and second tongues, a surface of
each tongue contacts the surface of bottom side 218 and acts to
lift load bearing structure 200 and any articles stacked on topside
216.
[0124] Because core 210 is made from the above-described expanded
polymer matrix, it has sufficient structural strength to be used as
a load bearing platform.
[0125] Leg inserts 250 are inserted into openings in legs 220-236.
Leg inserts 250 have a raised portion and are made of a material
that allows load bearing platform 200 to slide across surfaces when
being moved and otherwise positioned using, as a non-limiting
example, a forklift truck.
[0126] The load bearing platform according to the invention can
have a number of configurations, especially regarding the number
and placement of legs and leg inserts. FIG. 10 shows a non-limiting
example where load bearing platform 300 includes legs 312, 314,
316, 318, 320, 322, 324, 326, 328, and 330 extending from bottom
surface 310 of load bearing platform 300. In the configuration of
load bearing platform 300, the corner legs 312, 316, 326, and 330
are not as long as legs 314, 318, 320, 322, 324, or 328. Legs 312,
316, 326, and 330 have on leg insert 350 and legs 314, 318, 320,
322, 324, and 328 have one or more leg inserts (two are shown
although any suitable number of leg inserts can be used). As
described above, the legs are spaced apart so that the space there
between can accept the tongues of a forklift truck.
[0127] In embodiments of the invention, the load bearing platform
includes a "bottom skin" to provide additional strength, ease of
maneuvering with a fork-lift and aesthetic qualities. As shown in
FIGS. 11 and 12, skinned platform 400 includes expanded polymer
matrix core 402 and skin 404, which is adapted to receive the legs
and bottom side of core 402. In particular embodiments of the
invention, core 402 can be any of load bearing structures or
platforms 8, 200, or 300 as described above. As such, legs 412,
414, 416, 418, 420, 422, 424, 426, 428, and 430 extending from
bottom surface 410 of skin 404 and each accept a leg of core
402.
[0128] In embodiments of the invention, leg inserts 50 can be
inserted into leg insert openings (not shown) in skin 404 by
pushing them into openings (not shown) in the legs as described
above.
[0129] In some embodiments of the invention, a wheel or other
suitable device that provides a rolling mechanism is mounted on,
molded into, or otherwise attached to inserts 50 as described
above.
[0130] Core 402 fits securely within skin 404 to form skinned
platform 400.
[0131] Skin 404 can be made by known thermoforming techniques,
where a plastic sheet is heated and formed to desired shape through
the use of one or more of a plug or air pressure pushing the
plastic into the form, and/or vacuum drawing the plastic into the
form.
[0132] Skin 404 can be made from any suitable thermoplastic
material that maintains its strength and has a glass transition
temperature higher than the conditions of use for the present load
bearing structure or platform.
[0133] Suitable thermoplastic materials include polymers and
polymer compositions made up of materials that can be repeatedly
softened by heating and hardened again on cooling. Useful
thermoplastic materials in the invention include, but are not
limited to homopolymers and copolymers of styrene, homopolymers and
copolymers of C.sub.2 to C.sub.20 olefins, homopolymers and
copolymers of C.sub.4 to C.sub.20 dienes, polyesters, polyamides,
homopolymers and copolymers of C.sub.2 to C.sub.20 (meth)acrylate
esters, polyetherimides, polycarbonates, polyphenylethers,
polyvinylchlorides, copolymers of styrene, C.sub.4 to C.sub.20
dienes and (meth)acrylonitrile, cured thermoset materials, a
non-limiting example being polyurethanes, and combinations
thereof.
[0134] Optionally, reinforcing materials and/or fillers can be
incorporated into the thermoplastic materials including, but not
limited to carbon fibers, aramid fibers, glass fibers, metal
fibers, woven fabric or structures of the mentioned fibers,
fiberglass, carbon black, graphite, clays, calcium carbonate,
titanium dioxide, woven fabric or structures of the
above-referenced fibers, and combinations thereof.
[0135] Skin 404 can have a thickness of at least 0.1 mm, in some
cases at least 0.25 mm, and in other cases at least 0.5 mm and can
have a thickness of up to 1.5 mm, in some cases up to 1 mm, and in
other cases up to 0.75 mm. The thickness of skin 404 will depend on
the intended use of the load bearing structure or platform.
[0136] Typically, skin 404 will have dimensions that mirror those
of core 402. As a non-limiting example, core 402 can have a shape
and dimensions that correspond to edge 12 or 212 along with the
legs of load bearing platforms or structures 8 or 200.
[0137] In some embodiments of the invention, instead of covering
the entire underside of core 402, skin 404 comprises a plurality of
sleeves, one for each leg of core 402 that is form fitting over the
legs. In this embodiment, the sleeves can be made of the same
materials as core 402 and can similarly be adapted to receive a leg
insert.
[0138] Because the load bearing structures of the present invention
are made from the above-described expanded polymer matrix, they are
generally lighter in weight than conventional wood pallets, but can
be handled in the same way because of the inclusion of the leg
inserts as described above. As such, the present load bearing
structures are ideally suited for air transport and other
weight-limited transport situations allowing more goods to be
shipped per trip than when traditional wood pallets are used.
[0139] The present invention has been described with reference to
specific details of particular embodiments thereof. It is not
intended that such details be regarded as limitations upon the
scope of the invention.
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