Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: RACKABLE PALLLETS MADE OF RECYCLED PLASTIC COMPOSITE
FILED OF THE INVENTION
The present invention is directed to shaped pallets made of recycled plastic
composite, particularly those shaped to be rackable and the: process for
manufacturing
the pallets.
BACKGROUND OF THE INVENTION
There are two different pallet materials presently in use including wood and
plastic. While wood pallets are the most commonly utilized because of their
lower cost,
plastics are more preferred for their long service cycle, easy clean and
recyclability.
Amongst such materials, wood is particularly desirable for its strength and
creep
resistance. Wood does however have drawbacks. Since all environmental
concerns,
wood resource is limited. Wood decays and mildew grows v~hen moisture and
temperature are at right level. Since wood is easily infected by many
different insects,
pallets made of infected wood spread the insects around the world while they
are
transported with goods.
There have been attempts to construct pallets of plastic material having the
features of wood pallets but do not have some of the drawbacks. Such plastic
pallets
are of relatively long service cycle and can be cleaned easily. Plastic also
has an
advantage of being processed very efficiently. Examples of such plastic
pallets are
described in US patents among others:
There still remains a need for an economical to manufacture shaped pallets
having the strength and creep-resistance of wood pallets.
SUMMARY OF THE INVENTION
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The present invention is directed to a shaped plastic pallet. The pallet is
constructed of the combination of a thermoplastic and a fiber reinforcement in
an
amount to provide a final reinforcement content to pallet of between about 1 %
and
about 70% by weight based upon the total weight of the pallet. Another
structural
reinforcement is used to provide creep-resistance of the pallet when it is
loaded.
In an aspect of the invention, the thermoplastic is a commingle plastic.
In another aspect of the invention, the commingle plastic is a combination
polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene
(PS),
polyethylene terephthalate (PET) and acrylic derived from recycled material.
In yet another aspect of the invention, the fiber reinforcement is on or more
organic fibers selected from the group consisting of wood fiber, cotton fiber,
and other
agriculture fibers.
In yet anther aspect of the invention, the structural reinforcement is steel
beam.
BRIEF DESCRIBTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of a plastic pallet of the present invention is
illustrated in
the attached figure. The pallet is sized approximately equal to that of
traditional wood.
pallet having a width of approximately 48 inches, a total length of
approximately 40
inches and a depth of approximately 5112 inches. The top portion of the pallet
is the
deck for carrying goods. On the surface the deck, embossed rings provide anti-
slip
mechanism to prevent goods moving from the pallet. The bottom portion is a
nine legs
support system, which are molded one piece with the deck. The support system
also
provides access for fox-lifter moving the pallet. The structural reinforcement
system is
also molded with pallet.
The plastic pallets of the present invention are constructed of the
combination of
a commingle thermoplastic, preferably a polyolefin based polymer, and a
reinforcement
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fiber in an amount to provide a final fiber content to the pallet of between
about 1
percent and about 70 percent by weight. The provision of the fiber content in
the tile
provides the plastic with suitable shrinkage. Preferably, the polyolefin is
one or more
polymers selected from a polyethylene, a polypropylene, a polyvinyl chloride,
polystyrene, polyethylene tetephthalete, and acrylic, most preferably a
combination of a
polyethylene and a polypropylene. The polypropylene may be a homopolymer or a
copolymer with another suitable thermoplastic elastomer such as EPDM, ethylene
propylene terpolymer: The polyethylene may be high density polyethylene
(HDPE), low
density polyethylene (LDPE) or linear low density polyethylene (LLDPE). While
the
polyolefin polymer may be virgin material, it is preferred that the polyolefin
be derived
from recycled material. By utilizing recycled material, the cost of the pallet
is greatly
reduced.
The fiber reinforcement is preferable one or more fibers selected from the
group
consisting wood fiber, cotton fiber or agriculture fiber. Once again, while
the fiber
reinforcement may also be virgin material; it is preferred for reasons of
economy that
the fiber reinforcement also be derived from recycled material.
The commingle polymer is generally present in an amount of 60 to 90 percent by
weight and the reinforcement fiber is generally present in the amount of 10 to
40
percent by weight. Preferably, the commingle polymer is present in an amount
of 70 to
80 percent by weight and the reinforcement fiber is present in an amount of 20
to 30
percent by weight.
Structural reinforcement is a steel structure, which carries the load. The
steel
may be high carbon, media carbon or low carbon steel, preferred low carbon
steel. The
cross-section of the steel beam may I shape, round shape, square shape, and T
shape,
preferred square shape.
The shaped plastic pallet of the present invention maybe colored to any
desired
color by the addition of pigments commonly employed in the manufacture of
molded
thermoplastic materials. Depending upon the nature of the recycled material
used for
the shaped plastic tile, additional pigments may or may not be required.
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The plastic pallets are manufactured by mixing the commingle plastic and
reinforcement fiber to provide for a relatively uniform mixture and then
molding the
mixture into the pallet shape. When utilizing virgin material in the form of
powder,
pellets or flakes, the polyolefin plastic and reinforcement fiber are mixed
and then
molded with structural reinforcement utilizing compression molding.
When utilizing recycled material it may be necessary to regrind the material
prior
to the molding depending upon the physical nature of the recycled material. If
the
recycled material is provided in a small enough particles size it may be
handled in a
manner similar to virgin material by merely mixing, then melting and molding
the
material utilizing compression molding, If the recycled material has not been
reduced in
particles size or bulk it is generally necessary to first reduce the bulk in
particles size by
grinding or clensifying the material into suitable size particles for the
molding operation.
The mixture of plastic and fiber reinforcement is melted by conventional
plastic
process methods such as extruder or high intensity mixer. Molted mixture is
then
transferred to a mold in a compression molding machine. After cooling,
finished pallet is
ejected from the mold.
The use of steel beam results in a structure to resist creep when the pallet
is
racked with a heavy loading. Should the pallet is loaded with goods, the
structural
reinforcement will take most of the loading. Creep development would be-
interrupted by
the steel structure. The steel beam can be molded with molted mixture during
the
compression molding or inserted after the pallet is molded.
The shaped pallet of the present invention provide for an economical
manufactured pallet that replicates the desired performance of wood pallef
with long
serve life and easy cleaning. The pallet is as easy to use as conventional
wood pallet.
Although various preferred embodiments of the resent invention have been
described herein in detail, it will be appreciated by those of skill in the
art that variation
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may be made thereto without departing from the spirit of the invention or the
scope of
the appended claims.
