CA2274386A1

CA2274386A1 - Process for making a wood-thermoplastic composite hybrid and product thereof

Info

Publication number: CA2274386A1
Application number: CA 2274386
Authority: CA
Inventors: Mark F. Lang
Original assignee: Individual
Current assignee: Saint Gobain Technical Fabrics Canada Ltd
Priority date: 1998-06-30
Filing date: 1999-06-10
Publication date: 1999-12-30

Abstract

A process for forming a wood-thermoplastic composite hybrid comprising the steps of providing a film comprising a malefic anhydride modified polyolefin, applying a wood layer and thermoplastic layer to the modified polyolefin film, heating and pressing the modified polyolefin film, wherein the modified polyolefin film forms a liquified layer between the wood layer and thermoplastic layer, and, cooling the wood layer, modified polyolefin film and thermoplastic layer sufficiently to form a wood-thermoplastic composite hybrid. The hybrid may be used in support structures, such as truck trailer flooring, shipping containers, scaffolding, and standing platforms.

Description

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 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 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.

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;

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

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 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.
_7_ 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 _g_ 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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.

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.

Claims

1. 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;
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.

2. The process of claim 1, wherein the reinforcing agents are thermoplastic strengthening components selected from the group consisting of carbon fibers, glass fibers, aramid fibers, SPECTRA R, liquid crystal polymers, and combinations thereof.

3. The process of claim 2, wherein the reinforcing agents comprise glass fiber.

4. The process of claim 1, wherein the film comprises at least one polyolefin having at least one functional moiety of malefic anhydride.

5. The process of claim 1, wherein the modified polyolefin is selected from the group consisting of polyethylene, polypropylene, and copolymers and combinations thereof.

6. The process of claim 1, wherein the thermoplastic layer comprises a thermoplastic homopolymers or copolymers selected from the group consisting of polyolefin, polyester, polyamide, polystyrene, polycarbonates, vinyl polymers, and combinations thereof.

7. The process of claim 6, wherein the thermoplastic layer comprises polyolefin.

8. The process of claim 7, wherein the thermoplastic layer comprises polypropylene.

9. The process of claim 1, wherein the modified polyolefin film is formed after being applied to one of the wood layer or the thermoplastic layer.

10. The process of claim 1, wherein the modified polyolefin film is applied on the thermoplastic layer prior to being applied on the wood layer.

PATENT

11. The process of claim 1, wherein the applied modified polyolefin film is heated to a temperature of from about 320°F to about 450°F.

12. The process of claim 1, wherein the heated modified polyolefm film is pressed at a pressure of from about 50 psi to about 150 psi.

13. The process of claim 1, wherein the pressed modified polyolefin film is cooled to a temperature of from about 250°F or less.

14. The process of claim 1, wherein the thermoplastic layer has a thickness of from about 1/4 inch or less.

15. The process of claim 1, wherein the wood layer has a thickness of from about 1 1/2 inch or less.

16. The process of claim 1, wherein the wood layer comprises oak.

17. A wood-thermoplastic composite hybrid product 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 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;

PATENT

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 the wood-thermoplastic composite hybrid.

18. A truck trailer flooring comprising the wood-thermoplastic composite hybrid of claim 17.

19. A support platform used as a weight-bearing surface selected from the group consisting of shipping container flooring, scaffolding, skateboards, snowboards, waterskis, snow skis and surfboards comprising the wood-thermoplastic composite hybrid of claim 17.

20. 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; and, wherein the polyolefin is located between the thermoplastic layer and wood layer.