U.S. patent application number 11/796908 was filed with the patent office on 2007-12-13 for load bearing structure.
Invention is credited to Michel Florentine Jozef Berghmans, Robert Stoffa.
Application Number | 20070283856 11/796908 |
Document ID | / |
Family ID | 38723607 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070283856 |
Kind Code |
A1 |
Berghmans; Michel Florentine Jozef
; et al. |
December 13, 2007 |
Load bearing structure
Abstract
A load-bearing platform that includes a base and a lity of legs
extending from one side of the base, the load bearing platform is
at least partly made expandable polymer matrix that includes an
polymer of a polyolefin and in situ polymerized aromatic
monomers.
Inventors: |
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: |
38723607 |
Appl. No.: |
11/796908 |
Filed: |
April 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60801167 |
May 17, 2006 |
|
|
|
Current U.S.
Class: |
108/51.3 ;
108/56.3 |
Current CPC
Class: |
B65D 2519/00338
20130101; B32B 2266/0228 20130101; B65D 2519/00034 20130101; B65D
2519/00268 20130101; B32B 5/20 20130101; B32B 2266/0242 20130101;
B32B 2266/025 20130101; B32B 3/30 20130101; B32B 2266/0292
20130101; B65D 19/0028 20130101; B32B 5/32 20130101; B32B 5/18
20130101; B32B 2439/00 20130101; B32B 2266/0207 20130101; B65D
2519/00835 20130101; B65D 2519/00069 20130101; B65D 2519/00288
20130101 |
Class at
Publication: |
108/51.3 ;
108/56.3 |
International
Class: |
B65D 19/00 20060101
B65D019/00 |
Claims
1. A load-bearing platform including a base and a plurality of legs
extending from one side of the base, wherein the load bearing
platform comprises an expandable polymer matrix that includes an
interpolymer of a polyolefin and in situ polymerized vinyl aromatic
monomers.
2. The load-bearing platform according to claim 1, wherein the
expandable polymer matrix comprises other expandable polymers.
3. The load-bearing platform according to claim 1, wherein the
polyolefin is 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.
4. The load-bearing platform according to claim 1, wherein the
vinyl aromatic monomers are selected from the group consisting of
styrene, alpha-methyl-styrene, ethylstyrene, chlorostyrene,
bromostyrene, vinyltoluene, vinylbenzene, and isopropylxylene and
admixtures thereof.
5. The load-bearing platform according to claim 1, wherein the
polyolefin is present in the interpolymer resin particles at a
level of from 20% to 80% by weight based on the weight of the
interpolymer resin particles and the vinyl aromatic monomers or
resulting polymers are present in the interpolymer resin particles
at a level of from 20% to 80% based on the weight of the
interpolymer resin particles.
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 2, wherein the
other expandable polymers are 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 2, 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 2, 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. A load-bearing platform including a base and a plurality of
legs extending from one side of the base, wherein the load bearing
platform comprises an expandable polymer matrix that includes
rubber modified styrenic polymers wherein the rubber constitutes a
continuous phase and the styrenic polymer constitutes a dispersed
phase.
15. The load-bearing platform according to claim 14, wherein the
styrenic polymers comprise residues from the polymerization of
vinyl aromatic monomers selected from the group consisting of
styrene, alpha-methylstyrene, ethylstyrene, chlorostyrene,
bromostyrene, vinyltoluene, vinylbenzene, and isopropylxylene and
admixtures thereof.
16. The load-bearing platform according to claim 14, wherein The
elastomeric polymers are selected from the group consisting of
copolymers comprising one or more conjugated dienes and one or more
of unsatured nitrites, one or more polar monomers, alkyl esters of
unsaturated carboxylic acids, alkoxyalkyl esters of unsaturated
carboxylic acids, acrylamide, methacryl-amide; N-substituted
acrylamides, vinyl chloride; aromatic vinyl monomers, and
combinations thereof.
17. The load-bearing platform according to claim 14, wherein the
expandable polymer matrix comprises a blowing agent and/or
plasticizer.
18. The load-bearing platform according to claim 14, 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.
19. The load-bearing platform according to claim 14 comprising a
layer material applied to a topside of the platform.
Description
[0001] This application claims the benefit of priority of U.S.
Provisional Application Ser. No. 60/801,167, filed May 17, 2006,
entitled "Load Bearing Structure", which is herein incorporated by
reference in its 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,
making 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 for shipping and/or storing articles traditionally
found in wood pallets weight.
SUMMARY OF THE INVENTION
[0013] The present invention provides a load-bearing platform that
includes a base and a plurality of legs extending from one side of
the base, where the load bearing platform is at least partly made
of an expandable polymer matrix that includes an interpolymer of a
polyolefin and in situ polymerized vinyl aromatic monomers.
DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a top perspective view of a load bearing platform
according to the invention; and
[0015] FIG. 2 is a bottom perspective view of a load bearing
platform according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] As used herein, the term "polymer" is meant to encompass,
without limitation, homopolymers, copolymers and graft
copolymers.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] As used herein, the term "styrenic polymers" refers to
homopolymers of styrenic monomers and copolymers of styrenic
monomers and another 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-methylethylene, 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.
[0027] 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.
[0028] 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.
[0029] As used herein, the term "expansion factor" refers to the
volume a given weight of expanded polymer bead occupies, typically
expressed as cc/g.
[0030] The present invention provides a load-bearing platform that
includes a base and a plurality of legs extending from one side of
the base.
[0031] The present load-bearing platform is made from an expandable
polymer matrix that includes an interpolymer of a polyolefin and in
situ polymerized vinyl aromatic monomers and optionally other
expandable polymers.
[0032] In 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.
[0033] In 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
pallets 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] In particular embodiments of the invention, the vinyl
aromatic resin includes polystyrene or styrene-butyl acrylate
copolymers.
[0042] 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.
[0043] 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.
[0044] The polymerization of the vinyl aromatic monomers, which is
absorbed in the polyolefin particles, is carried out using
initiators.
[0045] 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.
[0046] 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.
[0047] When the in situ polymerization of the vinyl aromatic
monomers is completed, the polymerized vinyl aromatic resin is
uniformly dispersed inside the polyolefin particles.
[0048] 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-butyl-peroxy)-hexyne-3,2,5-dimethyl-2,5-di-(benzoy-
lperoxy)-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.
[0049] In an embodiment of the invention, the interpolymer of a
polyolefin and in situ polymerized vinyl aromatic monomers includes
a rubber modified styrenic polymer 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.
[0050] In this embodiment, the rubber modified styrenic polymers
are prepared by: [0051] I) forming a dispersion of organic droplets
of an organic liquid phase in an aqueous phase, which can be
stationary or flowing, where the organic phase contains an organic
solution containing one or more elastomeric polymers dissolved in a
monomer solution that includes one or more aryl polymerizable
monomers, the organic droplets having an average diameter of from
about 0.001 mm to about 10 mm, and [0052] II) polymerizing the
monomers in the organic droplets in a low shear flow pattern.
[0053] In one aspect of this embodiment, a dispersion of organic
droplets is formed by pressure atomizing an organic phase below the
free surface of an aqueous phase, which can be stationary or
flowing.
[0054] In another aspect of this embodiment, a dispersion of
organic droplets of an organic liquid phase in an aqueous phase,
which can be stationary or flowing, is formed by applying
mechanical agitation.
[0055] The styrenic polymers can include residues from the
polymerization of vinyl aromatic monomers selected from styrene,
alpha-methylstyrene, ethylstyrene, chlorostyrene, bromostyrene,
vinyltoluene, vinylbenzene, and isopropylxylene and admixtures
thereof.
[0056] The elastomeric polymers can include copolymers of one or
more conjugated dienes such as but not limited to butadiene,
isoprene (i.e., 2-methyl-1,3-butadiene), 3-butadiene,
2,3-dimethyl-1,3-butadiene and 1,3-pentadiene, one or more of a
suitable unsatured nitrile such as acrylonitrile or
methacrylonitiles and optionally one or more of a polar monomer
such as acrylic acid, methacrylic acid, itaconic acid and maleic
acid, alkyl esters of unsaturated carboxylic acids such as methyl
acrylate and butyl acrylate; alkoxyalkyl esters of unsaturated
carboxylic acids such as methoxy acrylate, ethoxyethyl acrylate,
methoxyethyl acrylate, acrylamide, methacrylamide; N-substituted
acrylamides such as N-methylolacrylamide, N,N'-dimethylolacrylamide
and N-ethoxymethylolacrylamide; N-substituted methacrylamides such
as N-methylolmeth-acrylamide, N,N'-dimethylolmethacrylamide,
N-ethoxy-methylmethacrylamide and vinyl chloride. These copolymers
can also include repeat units from the polymerization of one or
more aromatic vinyl monomers such as but not limited to styrene,
0-, m-, p-methyl styrene, dimethylstyrene and ethyl styrene. These
types of copolymers are known as "acrylonitrile-butadiene rubbers"
or "acrylonitrile-butadiene-styrene rubbers" or collectively as
"nitrile rubbers" by those skilled in the art.
[0057] In some embodiments of the invention, the nitrile rubbers
can be partially hydrogenated in the presence of hydrogen,
preferably with a suitable hydrogenation catalyst.
[0058] The expandable polymer matrix of the invention 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.
[0059] 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, dischloro-fluoromethane,
dichlorodifluormethane, chlorodifluoro-methane and
dichlorotetrafluoroethane, etc. These blowing agents can be used
alone or as mixtures. If n-butane, ethyl chloride, and
dichlorotetrafluoroethane, 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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, 1-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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] Alternatively, the blowing agent and/or plasticizer can be
added to the first reactor during or after the polymerization
process.
[0069] 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.
[0070] 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.
[0071] The interpolymer resin and/or expandable polymer matrix
particles 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.
[0072] The expandable polymer matrix includes 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.
[0073] 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.
[0074] 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.
[0075] 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
forty inches 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.
[0076] 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. 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.
[0077] 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.
[0078] In order to provide a desirable surface finish and/or
texture and/or to minimize where and tear from repeated use, a
suitable layer material can be applied to topside 16 and optionally
edge 12.
[0079] Suitable layer materials that can be applied include rubber
modified styrenic polymers, polyamides, such as nylon,
polypropylene, polyethylene, and combinations thereof.
[0080] 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. In embodiments of the invention,
the density of the expanded polymer matrix in core 10 corresponding
to the portions 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.
[0081] 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.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] 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 can be applied around the outside
perimeter of the box or open-box structure to secure the parts in
position.
[0087] 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.
[0088] In another embodiment of the invention, the panels and top
panels are made from the expandable polymer matrix described
herein.
[0089] In other embodiments of the invention, the panels and top
panels are made of one or more other expandable polymers as
described above.
[0090] The panels and/or top panel 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.
[0091] 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.
* * * * *