Note: Descriptions are shown in the official language in which they were submitted.
CA 02274386 1999-06-10
B8427
PROCESS FOR MAKING A WOOD-THERMOPLASTIC COMPOSITE HYBRID
AND PRODUCT THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for making a wood-thermoplastic
composite hybrid and the hybrid product made by that process. More
particularly, the
process and product provide a hybrid composition by binding a wood layer and a
thermoplastic layer using a modified polyolefin. Most particularly, the
polyolefin film
comprises a malefic anhydride modified polypropylene.
2. Brief Description of the Related Art
Thermoplastics include a variety of polymeric compounds including polyolefins,
polyesters, and polyamides. The polymers may be used separately, or in
combination with
each other, to form solid structural pieces. Depending on the use of a
structural piece, the
polymeric compounds are combined in different proportions, and with different
additives,
for particular purposes. Changing proportions and/or additives changes the
physical
properties and characteristics of the thermoplastic structural piece.
Polyolefins, such polypropylene and polyethylene, are well known thermoplastic
resins. Polyethylene is produced in great quantity, and is used in such
applications as
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packaging films, containers and bottles. Physical characteristics of
polyethylene vary with
the amount of crystallization, and with the size and distribution of the
crystalline regions.
As crystallization density increases, polyethylene products generally become
stiffer and
stronger. Like polyethylene, polypropylene is a popular thermoplastic resin
because it is
lightweight and inexpensive. Polypropylene provides a flexible stiff
composition that is
resistant to chemical attack and heat. Polypropylene also provides significant
corrosion
resistance not found in many metal components. Polypropylene has been used in
a variety
of applications, such as a metal component replacement in automotive materials
and parts.
These polyolefms provide a stiff and lightweight structure. However,
polyolefins do not
possess polar surfaces, resulting in only a very weak polymer interface with
other materials.
As such, the polyolefins are not generally usefizl in combination with other
materials such
as wood.
Polyesters include such polymers as polyethylene terephthalate (PET) and
polybutylene terephthalate (PBT). PET is moderately priced, possesses
exceptional
dimensional stability and reasonable hydrolytic stability. PBT is softer than
PET, with
greater elasticity. Polyamide thermoplastics include nylon. Nylon provides
such
characteristics as abrasion resistance.
Thermoplastics may be combined with additives, such as talc, glass fibers,
glass
mats, and other reinforcing materials. These additives are used to vary or
change the
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physical properties of the thermoplastic materials. The type and amount of the
additive may
be varied to impart specific qualities to the thermoplastics, such as
increasing or decreasing
strength, flexibility and other characteristics.
SUMMARY OF THE INVENTION
The present invention provides a process for forming a wood-thermoplastic
composite hybrid comprising the steps of providing a modified polyolefin film
having a first
side and a second side, the film comprising at least one polyolefin having at
least one
functional moiety of an unsaturated carboxylic acid or anhydride thereof;
applying a wood
layer on the first side of the modified polyolefin film; applying a
thermoplastic layer on the
second side of the modified polyolefin film, the thermoplastic layer
comprising a
thermoplastic composite having reinforcing agents combined with at least one
thermoplastic
homopolymer or copolymer; heating the applied modified polyolefin film,
wherein the
modified polyolefin film forms a liquified layer between the wood layer and
thermoplastic
layer, thus attaching the modified polyolefin to the wood layer and the
thermoplastic layer;
1 S pressing the heated modified polyolefin film between the wood layer and
thermoplastic
layer, wherein the modified polyolefin film structurally bonds with the wood
layer and the
thermoplastic layer; and, cooling the pressed wood layer, modified polyolefin
film and
thermoplastic layer sufficiently to form a wood-thermoplastic composite
hybrid.
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PATENT B 8427
The present invention further provides a wood-thermoplastic composite hybrid
made
by the process of providing a modified polyolefin film having a first side and
a second side,
the film comprising at least one polyolefin having at least one functional
moiety of an
unsaturated carboxylic acid or anhydride thereof; applying a wood layer on the
first side of
the modified polyolefm film; applying a thermoplastic layer on the second side
of the
modified polyolefin film, the thermoplastic layer comprising a thermoplastic
composite
having reinforcing agents combined with at least one thermoplastic homopolymer
or
copolymer; heating the applied modified polyolefin film, wherein the modified
polyolefin
film forms a liquified layer between the wood layer and thermoplastic layer,
thus attaching
the modified polyolefin to the wood layer and the thermoplastic layer;
pressing the heated
modified polyolefin film between the wood layer and thermoplastic layer,
wherein the
modified polyolefin film structurally bonds with the wood layer and the
thermoplastic layer;
and, cooling the pressed wood layer, modified polyolefin film and
thermoplastic layer
sufficiently to form a wood-thermoplastic composite hybrid.
Additionally, the present invention provides a wood-thermoplastic composite
hybrid
comprising at least one thermoplastic layer attached to at least one wood
layer; wherein the
thermoplastic layer comprises reinforcing agents combined with at least one
thermoplastic
homopolymer or copolymer; wherein the wood layer combined with at least one
polyolefin
having at least one functional moiety of an unsaturated carboxylic acid or
anhydride thereof;
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and, wherein the polyolefin is located between the thermoplastic layer and
wood layer.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow diagram of the process steps for a preferred embodiment of
the
present invention;
FIG. 2 is a schematic representation of the process for forming the wood-
thermoplastic composite hybrid of the present invention;
FIG. 2A is a cross sectional view of the bonded wood layer, film and
thermoplastic
layer after heating and pressing;
FIG. 2B is a cross sectional view of the wood-thermoplastic composite hybrid
product of the present invention;
FIG. 3 is a prospective view of a wood-thermoplastic composite hybrid of the
present
invention being used as flooring in a truck trailer and on a container located
therein;
FIG. 4 is a cross sectional view of a wood-thermoplastic composite hybrid
comprising additional layers attached thereto; and,
FIG. 5 is a prospective view of several articles of manufacture using the wood-
thermoplastic composite hybrid of the present invention as a support
structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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The present invention provides a process for using a malefic anhydride
modified
polyolefin for attaching a thermoplastic layer to a wood layer. The invention
also provides
the wood-thermoplastic composite hybrid made by the process. The process and
hybrid
product of the present invention provide a reinforced and strengthened support
structure,
which may be used as wood replacement articles, and/or other such articles as
flooring for
transport trailers, shipping containers, and/or other support platforms such
as scaffolding,
skateboards, snowboards, waterskis, snow skis, surfboards, and other like
devices.
As seen in FIG. 1, a preferred embodiment the present invention comprises a
process
for forming 10 a wood-thermoplastic composite hybrid. The process includes the
steps of
forming a malefic anhydride modified polyolefin film 12, applying the formed
modified
polyolefin film against a wood layer 14, applying a thermoplastic layer to the
modified
polyolefin film opposite the wood layer side 16, heating the applied modified
polyolefin film
18, pressing the heated modified polyolefin film between the wood layer and
thermoplastic
layer 20, and chilling or cooling the pressed wood layer, modified polyolefin
film and
thermoplastic layer 22. Alternatively, the process may apply the modified
polyolefm film
and thermoplastic layer prior to the application of the modified polyolefin
film against the
wood layer. Applying a first component of the present invention to a second
component,
such as applying a thermoplastic layer to a modified polyolefin film, is
construed within the
present invention to encompass and be understood also to mean applying the
second
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component to the first component, i.e. applying a modified polyolefin film to
a thermoplastic
layer. Additionally, the modified polyolefin film, when applied to either the
wood layer or
thermoplastic layer, may be heated prior to or after the application of the
modified polyolefin
film to the sides of these layers. As such, the modified polyolefin film may
be formed prior
S to or after the application of the malefic acid anhydride modified
polyolefin onto and/or
against either the wood layer or thermoplastic layer, such as providing the
malefic acid
anhydride modified polyolefin as a powder which is dusted onto either layer,
and heating the
powder to form a modified polyolefin film. When desired, the film 30 may first
be formed
by heating the powder into a liquified layer between the wood layer and
thermoplastic layer.
The process 10 provides a material having the wood layer and thermoplastic
layer
bound into a singular structure. The modified polyolefin film provides the
interface between
the two layers. With the proper application of heat 18 and pressure 20, the
wood layer and
thermoplastic layer, with the modified polyolefin film therebetween, combine.
The filin
fuses into the wood layer, while also integrally binding with the
thermoplastic layer. This
1 S fusion and integral binding forms a material that comprises a wood-
thermoplastic composite
hybrid. The hybrid is a combination of the wood and thermoplastic materials in
such a
manner as to permanently interact or bind the materials together. This binding
interlocks the
materials causing the materials to adhere to each other with an affinity which
is equal to or
greater than the affinity that either the wood or thermoplastic has for self
adhesion to itself.
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Practically, this is shown when a physical pull force is exerted in a manner
to pull apart the
wood layer and thermoplastic layer components of a formed hybrid. Layers of
non-hybrids
are easily pulled apart and separated from each other. When attempting to pull
apart a wood-
thermoplastic composite hybrid, the wood layer and thermoplastic layers do not
separate
easily, and tend to rip sections of the wood and/or thermoplastic layers.
There is no a clean
break between the wood and thermoplastic materials, as the hybrid tends to
part in areas
which are not along the seal between the two layers.
FIG. 2 shows a schematic representation of the process 10 for forming the wood-
thermoplastic composite hybrid 44. The modified polyolefin 26 is applied to
the surface of
the wood layer 28 and forms a film 30. A thermoplastic layer 32 is placed on
top of the film
30 opposite the wood layer 28. The wood layer 28, thermoplastic layer 32, and
film 30
components are heated with heating and pressing elements 34 as the components
are moved
in a direction 36 toward a cooling press 38. As the wood layer 28,
thermoplastic layer 32,
and film 30 components are heated, the components also are pressed. The
pressed heated
wood layer 28, thermoplastic layer 32, and film 30 components form into a
bonded structure
42, as shown in FIG. 2A. FIG. 2A is used to represent that although the
components form
into the bonded structure 42, and the film 30 interpenetrates the wood layer
28 and
thermoplastic layer 32, the bonded structure 42 contains three distinct levels
of components.
After the wood layer 28, thermoplastic layer 32, and film 30 components are
heated and
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pressed with heating and pressing elements 34, the formed bonded structure 42
continues in
the direction 36. The bonded structure 42 continues to be pressed as it enters
the cooling
press 38, where the bonded structure 42 is chilled, forming into the hybrid
44, as shown in
FIG. 2B. FIG. 2B is used to represent that although the components still exist
within the
hybrid 44, the components have been fused, with the film 30 combining with
both the
thermoplastic layer 32 and wood layer 28.
As previously discussed, the modified polyolefin film 30 is positioned against
the
wood layer either prior to or after heating. In another embodiment, the
modified polyolefin
26 may be applied as a powder and heated to form a film 30. Alternatively, the
filin 30 may
be heated with the thermoplastic layer 32 prior to, after or concurrently with
the application
of the film 30 to the wood layer 28. When positioned against the wood layer 28
prior to
heating, the film 30 may be held in place by any fastening means suitable for
maintaining
the film 30 against the wood layer 28, such as tacks, glue, point heating, and
other like
anchor points, or the film 30 may rest against the wood layer 28 without any
anchor points.
Preferably the film 30 is applied as a powder between the thermoplastic layer
32 and wood
layer 28 prior to heating. With the film 30 placed against the wood layer 28,
the film 30 is
heated with the heating and pressing elements 34 to a temperature that allows
the film 30 to
bond with the wood layer 28. This temperature provides sufficient heat to
liquify the
modified polyolefin 26 in the film 30, while not causing the modified
polyolefin 26 to
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degrade during liquidiflcation. Preferably the film 30 is heated to a
temperature of from
about 320°F to about 450°F, more preferably from about
350°F to about 420°F, and most
preferably from about 380°F to about 390°F. Regardless of the
method for forming the film
30, the modified polyolefin 26 preferably has a generally even distribution of
modified
polyolefin 26 over the thermoplastic layer 32 and wood layer 28 as a film 30.
An even
distribution includes application of the modified polyolefin 26 such that the
resultant hybrid
44 incorporates the thermoplastic 32 and wood 28 layer bonding over a
substantial area of
a given surface. An even film 30 distribution provides the hybrid 44 with
uniform
performance characteristics over the entire surface area of the hybrid 44.
With the modified polyolefin 26 forming the film 30 in a heated state, the
wood layer
28 and film 30 are pressed together sufficiently to bond the wood layer 28 and
film 30. The
wood layer 28 and film 30 may be pressed prior to and/or during the
application of the heat.
Preferably, the wood layer 28 and film 30 are pressed together at a pressure
of from about
50 psi to about 150 psi, more preferably from about 50 psi to about 100 psi,
still more
preferably from about 50 psi to about 75 psi, and most preferably from about
50 psi to about
60 psi. The wood layer 28 and film 30 are pressed together for a sufficient
period of time
that allows the wood layer 28 and film 30 to be structurally bonded together.
Preferably the
heated wood layer 28 and film 30 are pressed together for a time period of
from about 10
minutes or less, more preferably from about 5 minutes to about 1 minute, and
most
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preferably from about 3 minutes to about 1 minute.
Application of the thermoplastic layer 32 to the film 30 may occur
simultaneously
with, prior to, or after, the application of the film 30 to the wood layer 28.
The polymeric
structure of the thermoplastic layer 32 and the film 30 form an integrated
structure when
heated together. The polymer components intermingle when heated, and remain
interlocked
when the thermoplastic layer 32 and film 30 are later cooled. Pressure applied
to the
thermoplastic layer 32 and film 30 enhances the intermixing of the polymer
components.
The temperature must be sufficient to melt or liquify the surface of the
thermoplastic layer
32 and the modified polyolefin 26 in the film 30, while not causing either the
thermoplastic
layer 32 or the modified polyolefin 26 to degrade during liquidification.
Preferably the
thermoplastic layer 32 and film 30 are heated to a temperature of from about
320°F to about
450°F, more preferably from about 350°F to about 420°F,
and most preferably from about
380°F to about 390°F. Preferably, the thermoplastic layer 32 and
film 30 are pressed
together at a pressure of from about 50 psi to about 150 psi, more preferably
from about 50
psi to about 100 psi, still more preferably from about 50 psi to about 75 psi,
and most
preferably from about 50 psi to about 60 psi. Preferably the heated
thermoplastic layer 32
and film 30 are pressed together for a time period of from about 10 minutes or
less, more
preferably from about 5 minutes to about 1 minute, and most preferably from
about 3
minutes to about 1 minute. Preferably, the film 30, wood layer 28 and
thermoplastic layer
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32 are heated and pressed together a single time.
After the application of the film 30 to the thermoplastic layer 32, and heat
pressing
the thermoplastic layer 32, wood layer 28, and film 30, the attached
thermoplastic-film-wood
of the bonded structure 42 is cooled sufficiently in the cooling press 38 to
form a structurally
bound hybrid 44 comprising the thermoplastic 32 and wood 28 layers, as shown
in FIG. 2B.
The cooling or chilling perfects the structurally bonded wood layer 28 and
thermoplastic
layer 32 into the hybrid 44. This chilling occurs at a temperature below the
melting
temperature (Tm) of the modified polyolefin 26 in the film 30. Preferably, the
film 30 is
chilled to a temperature of from about 360°F or less, more preferably
from about 350°F or
less, still more preferably from about 250°F or less, and most
preferably from about 90°F
or less. Although the film 30 may be chilled a$er the pressure is released,
preferably the
bonded structure 42 remains pressed, or under pressure, traveling from the
heating and
pressing elements 34 and through the cooling press 38.
Although it is preferred to combine the thermoplastic layer 28, modified
polyolefin
film 30 and wood layer 28 at one time, the film 30 may be bound to the wood
layer 28 in a
separate prior step than from binding the film 30 with the thermoplastic layer
32.
Additionally the film 30 may be bound to the thermoplastic layer 32 in a
separate prior step
from binding the film 30 with the wood layer 28. Regardless of the sequence of
binding the
film 30 to either layer, the hybrid 44 product which is formed from the
process 10 provides
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a superior structurally bonded composition.
The modified polyolefm 26 component of the hybrid 44 provides a continuous
film
30 that may be applied to any given wood layer 28 surface. Preferably the
modified
polyolefin 26 comprises homopolymers and/or copolymers of polyethylene,
polypropylene
and combinations thereof. More preferably, the modified polyolefin comprises
polyethylene
or polypropylene. Most preferably, the modified polyolefin comprises
polypropylene.
Polypropylene possesses a high melt flow that provides for easy molding.
Suitable modified polyolefins 26, in accordance with the present invention
include
modified polyolefin compositions having at least one functional moiety of
unsaturated
polycarboxylic acids or anhydrides thereof. Preferably, the modified
polyolefin 26
comprises a malefic anhydride part. The malefic anhydride may be grafted onto
the
polyolefin, forming a fiarlctionalized polyolefin 26 with the malefic
anhydride attached to the
polyolefin polymer backbone. The modified polyolefin 26 possess a functional
five-member
ring. The ring structure includes an internal oxygen adjacent to two carbonyl
carbons on
either side of the internal oxygen. Each carbonyl carbon is additionally
double bonded to an
oxygen. The degree of adhesion between the film 30 and wood layer 28 is
relative to the
number of malefic anhydride functional groups contained in a given amount of
polyolefin,
with the relationship measured in weight percentages. The preferred weight
percentage of
the malefic anhydride to polyolefin is determinable by those skilled in the
art for a particular
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use of the hybrid 44. The modified polyolefins 26 suitable for use in this
invention include
compositions described in U.S. patents 4,612,155 and 4,751,270, these patents
herein
incorporated by reference. Modified polyolefins 26 also are commercially
available from
companies such as Uniroyal Chemicals, a subdivision of Crompton & Knowles of
Stamford,
Connecticut, under the trademark Polybond~; AlliedSignal Chemicals of
Mornstown, New
Jersey under the trademark A-C~; and under the trademark Fusabond~,
manufactured by
E.I. duPont de Nemours and Company, Inc., of Wilmington, Delaware.
The wood layer 28 comprises wood and/or wood products such as wood laminate,
pressed wood composite, layered wood, boards, planks, chips, sections, and/or
combinations
thereof, and other such wood and wood-like materials. The types of wood
include, but are
not limited to, oak, pine, spruce, maple, cherry, and other such woods, the
selection of the
type of wood being determinable by those skilled in the art. Thickness 64 of
the wood layer
28 is any amount that facilitates reinforcement with a malefic anhydride
modified polyolefin
26 and thermoplastic layer 32. As such, the wood layer 28 thickness 64 may
vary between
different types of woods that are used, and range in thickness from about 2
inches or more,
2 inches to about '/4 inch, 1 %2 inch to about %2 inch, 1 inch to about %z
inch, etc, with the
thickness 64 of the wood layer 28 for different uses of the resultant hybrid
44 being
determinable by those skilled in the art.
The thermoplastic layer 32 comprises a thermoplastic composite composition of
any
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reinforced thermoplastic material suitable for combining with the wood layer
28, which non-
exclusively includes polyolefins, polyesters, polyamides, polystyrene,
polycarbonates, vinyl
polymers, and copolymers of such thermoplastics and/or combinations thereof.
Preferably
the thermoplastic layer 32 comprises a polyolefin or polyester, more
preferably a polyolefin,
and most preferably the thermoplastic layer 32 comprises a reinforced
polypropylene.
Suitable polyolefins of the present invention include polyethylene,
polypropylene,
combinations of polyethylene and polypropylene, and compound derivatives of
the
polyethylene and polypropylene, including copolymers. The polyethylene and
polypropylene may be high density, and/or combined with other polymers for
variations of
strength, flexibility and/or other desirable characteristics for a given
purpose.
Polyesters may include polyethylene terephthalate (PET) and/or polybutylene
terephthalate (PBT). Polyethylene terephthalate may include polymers made by
condensing
ethylene glycol with terephthalic acid or dimethyl terephthalate. The
polyethylene
terephthalate polymers of the present invention may be modified by the
inclusion of minor
amounts, e.g. less than about 25 percent by weight of the polymer, of common
conventional
co-monomers or modifying agent. Such co-monomers or modifying agents include
various
diols such as 1,4-butanediol, cyclohexanedimethanol, diethylene glycol and 1,3-
propanediol.
Likewise, such co-monomers or modifying agents may include various aliphatic
ro aromatic
diacids such as isophthalic acid and naphthalene dicarboxylic acid.
Additionally, the
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polyethylene terephthalate polymer of the present invention may be blended
with other
polyesters.
The thermoplastic composite composition of the thermoplastic layer 32 further
comprises additional components or reinforcing agents 46 that vary the
strength and/or other
characteristics of the thermoplastic layer 32. These reinforcing agents 46
include, but are not
limited to, such materials as fiberglass, carbon black, wood chips, talc,
metal particles,
carbon fiber, glass fiber, aramid fiber, nylon, liquid crystal polymers, an
additive
SPECTRA~ made by AlliedSignal Chemicals of Mornstown, New Jersey, and/or high
density polymeric components, and combinations thereof, and other such
materials that may
improve the characteristics of the thermoplastic layer 32. The reinforcing
agents 46 are
added in amounts that permit the thermoplastic layer 32 to be properly
reinforced. The
reinforcing agents 46 are preferably added in amounts of from about 60 percent
by weight
or more, more preferably from about 75 percent weight or more, and most
preferably from
about 75 percent weight to about 80 percent weight. The type and amount of the
reinforcing
agents 46 for a given use is determinable by those skilled in the art.
Preferably the
thermoplastic layer 32 has reinforcing agents 46 comprising carbon fiber,
glass fiber, aramid
fiber and combinations thereof. More preferably, the reinforcing agents 46
comprise carbon
fibers or glass fibers. Most preferably, the reinforcing agents 46 comprise
glass fibers.
The thermoplastic layer 32 comprises a thickness 60 suitable to a given use of
the
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resultant hybrid 44, with the appropriate thickness 60 for an intended use
being determinable
by those skilled in the art. For example, weight, strength, and cost vary
according to the type
of thermoplastic layer 32 material used. The thickness 60 for the
thermoplastic layer 32 may
be greater than'/o inch, but typically included ranges of from'/4 inch or
less, '/4 inch to about
1/64 inch, ~/a inch to about 1/32 inch, 1/a inch to about 1/16 inch, etc.
Additionally, the type
of reinforcing agent 46 may vary the amount of thermoplastic layer 32
thickness 60 required
for a given purpose. Carbon fibers provide superior strength to weight ratios,
whereas
aramid fibers provide less strength for a given amount of reinforcing agent
46. Glass fibers
provide less strength than aramid fibers. Additionally, carbon fibers cost
more than aramid
fibers, and aramid fibers cost more than glass fibers. Generally,
thermoplastic layers 32
comprising a thickness of from about '/4 inch or less are particularly useful
for many
manufactured articles. For use as truck trailer flooring, a thermoplastic
layer 32 comprising
a polypropylene thermoplastic containing glass fiber reinforcing agents 46
preferably
comprises a thickness 60 of from about'/4 inch or less, more preferably from
about 1/32 inch
1 S to about '/4 inch, and most preferably from about 1 /32 inch to about ~/a
inch.
The thickness 62 of the applied modified polyolefin film 30 comprises any
thickness
suitable for the intended use of forming the hybrid 44 sufficiently to bind
the wood layer 28
and the thermoplastic layer 32. Factors for determining the thickness 62 of
the polyolefm
film 30 include the types of thermoplastics being bound, the functionality of
the malefic
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anhydride 26, the types or type of wood used, the intended use of the hybrid
44, such as
flooring, siding, support structures, etc., the thickness of the layers 28 and
32 being bound,
the flexibility that is required of the hybrid 44, and other like factors,
with the optimum
thickness 62 being determinable by those skilled in the art. The modified
polyolefin film 30
preferably has a thickness 62 of from about 1/100 inch or less, more
preferably from about
1/1000 inch to about 1/100 inch, and most preferably from about 1/1000 inch to
about
5/1000 inch.
The overall thickness 66 of the hybrid 44 may be any thickness suitable for
its
intended use. The thickness of the wood layer 28 and the thermoplastic layer
32 may also
be varied in relation to each other. Variations in the thermoplastic layer 32
may allow for
a decrease in the amount of wood layer 28 thickness, while providing improved
characteristics as a replacement for a singular wood layer, such as wood
planking. As such,
the thickness 64 of the wood layer 28 may be minimized to an amount that
provides an
adequate hybrid 44 replacement for the wood planking for a given use. The
overall thickness
66 of the hybrid 44 preferably comprises a thickness of from about 1/16 inch
to about 2
inches, more preferably from about'/e inch to about 1'/Z inch, and most
preferably from about
'/s inch to about 1'/4 inch.
In practice, the thermoplastic layer 32 is formed using melt impregnation,
commingled fibers, or powder impregnation of a thermoplastic resin with
reinforcing agents
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46. The thermoplastic layer 32 may be either a unidirectional or
multidirectional oriented.
The modified polyolefin film 30 may be formed by lamination, extruding a film
30 from
polypropylene pellets, or pulverizing the modified polyolefin 26 into a
powder. The formed
film 30 of the modified polyolefin 26 may comprise a continuous sheet of the
modified
polyolefin 26 which may be cut to fit a particular use. The film 30 also may
be a liquified
modified polyolefin 26. In one embodiment of the present invention, the film
30 is placed
onto the thermoplastic layer 32, and the film 30 and thermoplastic layer 32
are
simultaneously placed into the heating and pressing elements 34 and melted
together,
forming a new surface on the thermoplastic layer 32. The wood layer 28 is then
placed onto
the new surface while the melted film 30-thermoplastic layer 32 combination
remains
sufficiently hot to maintain a molten state. The wood-film-thermoplastic
combination is
again placed into the heating and pressing elements 34 and pressure is applied
to the entire
combination by clamping the wood-film-thermoplastic combination between two
hot platens,
thereby attaching and binding the wood layer 28 to the thermoplastic layer 32,
and forming
the wood-film-thermoplastic bonded structure 42. The bonded structure 42 is
transferred
into the cooling press 38 where pressure is maintained or reapplied while
simultaneously
cooling the resin below its melt temperature.
In an alternative continuous method, the thermoplastic layer 32 is passed over
a
heated surface to melt the thermoplastic resin along one surface, and the
modified polyolefin
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PATENT B 8427
film 30 is applied to the surface, with continuous heat being applied to melt
the thermoplastic
layer 32 and film 30 together. The modified polyolefin film 30 may be applied
as a powder
that is liquified into a film on contact with the heated thermoplastic layer
32. Once melted
together, the wood layer 28 is applied on the opposite side of the film 30
from the
thermoplastic layer 32, and the combination wood-film-thermoplastic
combination is pressed
together between rollers in the heating and pressing elements 34 to compact
the materials
together into the wood-film-thermoplastic bonded structure 42. The bonded
structure 42 is
cooled below the melt temperature of the modified polyolefin 26 forming the
hybrid 44.
FIG. 3 shows a cut-away of a truck trailer 50 having a hybrid 44 being used as
a
wood replacement for truck flooring 52. The present invention provides a
hybrid 44
composition for transport truck trailers SO that reduces the amount of
required wood. The
area within the flooring 52 of the truck trailer may have a size of about 40
feet long and 8
feet wide. Doors and sides may also contain the present invention. These
trucks may carry
loads weighing 40,000 pounds over extended distances. The hybrid 44, having at
least one
wood layer 28 and at least one thermoplastic layer 32, provides the wood
replacement
attached to the truck base 54. When used as flooring 52 for a truck trailer
50, wood planking
having a thickness of one inch may be replaced by the hybrid 44 of the present
invention
with a thickness 66 of less than one inch, and having improved strength,
resistance, longevity
and flexibility. For use as flooring within a truck trailer 50, the wood layer
28 of the hybrid
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44 preferably comprises a thickness 64 that ranges from about 1 inch to about
1'/2 inch, more
preferably from about 1 inch to about 1'/s inch, and most preferably from
about 1 1/16 inch
to about 1'/a inch. When used in trailer flooring 52, the thickness 60 of the
thermoplastic
layer 32 preferably ranges from about'/4 inch or less, more preferably from
about 1/32 inch
to about'/4 inch, and most preferably from about 1/32 inch to about'/s inch.
The thickness
62 of the applied modified polyolefin film 30 comprises any thickness suitable
for the
intended use of forming the hybrid 44 sufficiently to bind the wood layer 28
and the
thermoplastic layer 32 as trailer flooring 52. For use in the deck area of a
truck 52, the
modified polyolefin film 30 preferably has a thickness 62 of from about 1/100
inch or less,
more preferably from about 1/1000 inch to about 1/100 inch, and most
preferably from about
1/1000 inch to about 5/1000 inch. The overall thickness 66 of the hybrid 44
preferably
comprises a thickness 60 of from about 1/16 to about 2 inches, more preferably
from about
'/e inch to about 1 %Z inch, and most preferably from about'/a inch to about
1'/4 inch.
As further seen in FIG. 3, a shipping container 48 may comprise flooring or
siding
of the hybrid 44. The hybrid 44 provides the structural strength needed for
supporting items
carned within the container 48. The container 48 may have singular pieces of
the hybrid 44
forming the container, or planking of the hybrid 44 may be used together to
form the
individual parts of the container 48. The types of wood and thermoplastic
materials, the
thickness of the layers, and other such factors are determinable by those
skilled in the art for
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PATENT B8427
a given use of the container 48.
As a wood replacement, the hybrid 44 possesses a structurally superior
material
compared to wood, with reduced weight. This provides a practical replacement
for wood
products used in a variety of ways, such as truck trailers, containers,
scaffolding, sports
S equipment, walls, and other traditionally known wood uses. The hybrid 44
allows reduced
cost for a wood replacement product having many of the desirable traits of
wood, such as
appearance, color, texture, and the like, while reducing the amount of wood
thickness and
maintaining improved shear strength, durability, resistance to moisture and
longevity.
Generally, a hybrid 44 thickness 66 of from about 1 %2 inch or less is
particularly useful for
many manufactured articles.
FIG. 4 shows a multilayered 70 composite material containing the wood layer 28
and
the thermoplastic layer 32, with the thermoplastic layer 32 containing
reinforcing agents 46
of glass fibers. The wood layer 28 and thermoplastic layer 32 have been
combined together
with a modified polyolefin film to form the hybrid 44. One or more additional
layers 68 may
be added to the hybrid 44 of the wood 28 and thermoplastic 32 layers. The
additional layers
may include any material compositions that are suitable for the multilayered
70 composite
material. The additional layers may contain sequenced or random wood,
thermoplastic,
metal, or other such layers such as teflon, aluminum, etc. throughout the
multilayered 70
structure. When appropriate, layers may be joined or fixed together with
adhesive
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compositions or glues that do not contain a malefic anhydride modified
polyolefin, provided
that the multilayered 70 composite contains at least one hybrid 44 layer.
Large sections of
the hybrid 44 may be used to cover the flooring, sides and/or other parts of
the trucks. The
hybrid 44 may comprise any convenient size for structuring trailer flooring
52, such as
hybrid 44 sections ranging from about 12 feet to about 15 feet long and from
about 12 inches
to about 16 inches wide. Use of different woods and/or thermoplastics within
the hybrid 44,
such as oak, pine, etc., may change the characteristics of the hybrid 44 for
strength, look,
durability, and the like. Generally, the type of wood planking being replaced
for a certain
function may be the same type of wood used in the hybrid 44 that replaces the
planking. For
example, a hybrid 44 containing an oak wood layer 28 may be used to replace
oak planking
in the flooring 52 within the truck trailer 50. Although the amount of oak
needed decreases
with the use of the hybrid 44, the performance of the hybrid 44 is superior to
the original oak
planking as truck flooring 52. However, different woods may be used in the
hybrid 44 than
the type of wood planking being replaced. The amount of wood within the hybrid
44 varies
1 S according to the use of the hybrid 44, type of wood within the hybrid 44,
and other functional
properties, with the amount of wood within the hybrid 44 being determinable by
those skilled
in the art for a given use.
The hybrid 44 product provides wood or wood planking replacements having
superior wear and endurance performance at a reduced weight, yet with the same
general
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PATENT B8427
look. The use of the hybrid 44 within the hundreds of thousands of truck
trailers 50, and
other vehicles provides for reduced fuel costs during transport. Additionally,
the reduced
weight allows for easier handling of the hybrid 44, in the installation into
and removal from
the trucks. The reduced cost of the hybrid 44 makes the present invention
viable as a
practical replacement for the wood flooring currently in use. Problems of wood
rot and
deterioration from snow, rain, salt and other road elements are minimized.
Placement of the
hybrid 44 in the truck trailer 50 with the wood side up provides durability,
and having the
thermoplastic side down provides strength.
As seen in FIG. 5, the hybrid product of the present invention may be used as
a wood
replacement for commonly used wood support structures, such as support
structures on
which to stand. Wood replacements include paneling, planking, table tops,
furniture, doors,
lift surfaces, boats hulls, chairs, and/or other like uses, particularly in
uses that having a
wood appearance, limited thickness, and a given strength and/or flexibility.
Preferably, the
hybrid 44 comprises a weight-bearing support platform for standing and/or
walking, non-
exclusively including such devices as scaffolding, ramps, and other like
working surfaces,
and skateboards 82, surfboards 84, snowboards 86, waterskis, snow skis 88,
and/or other like
recreational devices.
Example 1
Oak paneling measuring 12 inches wide, 20 feet long and 1'/e inch thick was
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continuously laminated with a malefic anhydride modified polypropylene at a
temperature
of 200°C. The malefic anhydride modified polypropylene was manufactured
by Uniroyal
Chemicals, a subdivision of Crompton & Knowles of Stamford, Connecticut, under
the
trademark Polybond~. A glass reinforced thermoplastic layer of polypropylene
measuring
'/e inch thick was applied to the opposite side of the applied modified
polypropylene. The
combination wood, modified polypropylene and thermoplastic remained heated at
200°C for
2 minutes in a drying oven, and then was pressed at a pressure of SO psi for 3
minutes. The
combination was chilled to room temperature, forming a hybrid. The formed
hybrid was cut
to size and fitted into the bed area of a truck trailer as flooring.
Example 2
A malefic anhydride modified polypropylene, manufactured by Uniroyal
Chemicals,
a subdivision of Crompton & Knowles of Stamford, Connecticut, under the
trademark
Polybond~, was extruded between oak planking (1 inch thick) and a glass fiber
reinforced
polypropylene layer ('/2 inch thick) using a glue gun having a tip temperature
of
approximately 120°C. The combination wood, modified polypropylene and
thermoplastic
was heated to 200 ° C for 2 minutes in a drying oven, and then was
pressed at a pressure of
100 psi for 5 minutes. The combination was chilled to room temperature,
forming a hybrid.
The formed hybrid is cut to size and fitted together to form a shipping
container having the
dimensions of 6 feet by 4 feet by 4 feet.
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Example 3
A malefic anhydride modified polypropylene, manufactured by Uniroyal
Chemicals,
a subdivision of Crompton & Knowles of Stamford, Connecticut, under the
trademark
Polybond~, was extruded between oak planking ( 1'/z inch thick) and a glass
fiber reinforced
polypropylene layer ('/z inch thick) using a glue gun having a tip temperature
of
approximately 120°C. The combination wood, modified polypropylene and
thermoplastic
was heated to 200°C for 2 minutes in a drying oven, and then was
pressed at a pressure of
1 SO psi for 5 minutes. The combination was chilled to room temperature,
forming a hybrid.
The formed hybrid was cut and shaped as a standing platform for a skateboard.
The foregoing summary, description, examples and drawings of the present
invention
are not intended to be limiting, but are only exemplary of the inventive
features which are
defined in the claims.
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