US20070235705A1

US20070235705A1 - Composite fence

Info

Publication number: US20070235705A1
Application number: US11/760,528
Authority: US
Inventors: Christopher Burger; Kevin Burt; John Frechette
Original assignee: Crane Plastics Co LLC
Current assignee: Crane Building Products LLC
Priority date: 2003-02-27
Filing date: 2007-06-08
Publication date: 2007-10-11

Abstract

The apparatus and method of the present invention is directed to an improved composite fence and, more particularly, to a composite fence made of cellulosic fillers and/or inorganic fillers. An alternative embodiment of the present invention is directed to a fence in which a substrate is embedded in a plastic composite. One example of a component of the present invention is comprised of a substrate sheet that is embedded in a plastic composite. Another example of a component of the present invention is a perforated substrate that is embedded in a plastic composite.

Description

This is a continuation of U.S. application Ser. No. 10/920,037, filed Aug. 17, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/758,737, filed Jan. 16, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/452,612, filed Jun. 2, 2003, which claims the benefit of U.S. Provisional Application No. 60/450,415, filed Feb. 27, 2003, each of which is hereby incorporated by reference in its entirety.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to components made from composite materials. More particularly, the present invention is directed to a fence and/or its components made from a composite material. Examples of composite materials include plastic composites that include cellulosic fillers and/or inorganic fillers. Cellulosic-filled plastic composites may also be known as synthetic wood composites or, more simply, wood composites.
Generally, fence components such as fence rails, picket panels, posts, etc. are continuously exposed to environmental conditions, such as rain, ice, and snow. In fact, it is well known that the retention of moisture is a primary cause of the warping, splintering, discoloration, and general deterioration of natural woods. In order to slow this degradation of a wood fence, the wood is typically pre-treated with a water-proofing chemical to prevent it from retaining moisture. This pre-treatment adds to the initial cost of the fence. Also, in order to continue to maintain the moisture resistance of the wood, the fence must be regularly treated, preferably annually, with the water-proofing chemical. This regular waterproofing increases the time and costs to maintain the wood fence. Even with this preventative maintenance, wood fences still experience many, if not all, of the deteriorating effects described above.
In addition, the supply of natural woods for construction and other purposes is dwindling. When a tree is harvested for manufacturing purposes, it takes many years to grow another tree of similar size in its place. As a result, many are concerned about conserving the world's forests, and the cost of natural woods has risen. In light of these factors, a tremendous demand has developed in recent years for wood composites that exhibit the look and feel of natural woods.
Wood fiber/polymer composites and wood flour/polymer composites have been used as replacements for all-natural wood, particle board, wafer board, and other similar materials. Wood composites may provide desired appearance, strength, durability, weatherability, and other structural characteristics. As compared to natural woods, wood fiber/polymer composites and wood flour/polymer composites may offer superior resistance to wear and tear. In addition, wood fiber/polymer composites and wood flour/polymer composites may have enhanced resistance to moisture. Moreover, wood fiber/polymer composites and wood flour/polymer composites may be sawed, sanded, shaped, turned, fastened, and finished in a similar manner as natural woods.
In addition, like natural wood, plastic composites are subject to stress caused by load conditions or the conditions of the environment. For instance, plastic composites can expand, contract, bend, warp, creep, or undergo other structural changes over time in response to environmental or load conditions. In addition, fasteners may withdraw from plastic composite fences in a manner similar to which fasteners back out of natural wood. Accordingly, there is a need for further improving the structural characteristics of plastic composite fences.
The apparatus and method of the present invention is directed to an improved composite fence and, more particularly, to a composite fence made of cellulosic fillers and/or inorganic fillers. An alternative embodiment of the present invention is directed to a fence in which a substrate is embedded in a plastic composite to further improve the strength of a fence component and fastener retention. Any of a variety of substrates and plastic composites may be used to achieve the desired component characteristics. One example of a composite fence component of the present invention is a picket panel comprised of a cellulosic filler, a polymer, a lubricant, and an inorganic filler. Another example of a composite fence component includes the previous ingredients plus an endothermic or exothermic blowing agent. In another alternative embodiment of a composite fence of the present invention, the composite fence includes a first fence component comprised of a cellulosic filler, a polymer, a lubricant, an inorganic filler, and a exothermic or endothermic blowing agent and a second fence component comprised of a plastic composite having a substrate sheet embedded in it, wherein the plastic composite may be comprised of a cellulosic filler, a polymer, a lubricant, and an inorganic filler.
In addition to the novel features and advantages mentioned above, other features and advantages of the present invention will be readily apparent from the following descriptions of the drawings and exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial, perspective view of an exemplary embodiment of a composite fence of the present invention.
FIG. 2 is a partial, side elevational view of an alternative embodiment of a composite fence component of the present invention, wherein a substrate is exposed for illustrative purposes.
FIG. 3 is an end elevation view of the composite fence component of FIG. 2, wherein a substrate is exposed for illustrative purposes.
FIG. 4 is a partial, perspective view of an alternative embodiment of a composite fence of the present invention including the component of FIG. 2.
FIG. 5 is a diagram of an exemplary embodiment of an extruder and an inline die system.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

The apparatus and method of the present invention is directed to a composite fence. More particularly, the apparatus and method of the present invention is directed to a fence made of plastic composites that include cellulosic fillers and/or inorganic fillers. Cellulosic-filled plastic composites may also be known as synthetic wood composites or, more simply, wood composites.
The inventors have discovered that a fence, in particular, may benefit from the present invention. For the same reasons, various fence components may also benefit from the present invention. The fence of the present invention may take any form of a fence including, but not limited to, split rail, picket, privacy, and any other type of fence. FIG. 1 shows an exemplary embodiment of a composite fence 10 of the present invention. The fence or assembly 10 includes a post 12, plank 14, and rail 16. The plank 14 may be connected to rail 16 by fasteners 18, which extend through plank 14 and into rail 16. The size and position of the fasteners 18 may vary without changing the scope of the present invention.
Fence 10 may have one component or more components comprised of cellulosic-filled and/or inorganic-filled plastic composites of the present invention. Examples of plastic composites include, but are not limited to, polyolefin composites and polyvinyl chloride composites. A cellulosic-filled plastic composite may be comprised of materials that include, but are not limited to, cellulosic fillers, polymers, inorganic fillers, cross-linking agents, lubricants, process aids, stabilizers, accelerators, inhibitors, enhancers, compatibilizers, blowing agents, foaming agents, thermosetting materials, pigments, anti-oxidants, and other suitable materials. Examples of cellulosic fillers include sawdust, newspapers, alfalfa, wheat pulp, wood chips, wood fibers, wood particles, ground wood, wood flour, wood flakes, wood veneers, wood laminates, paper, cardboard, straw, cotton, rice hulls, coconut shells, peanut shells, bagass, plant fibers, bamboo fiber, palm fiber, kenaf, flax, and other similar materials.
Examples of polymers include multilayer films, high density polyethylene (HDPE), low density polyethylene (LDPE), chlorinated polyethylene (CPE), polypropylene (PP), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), acrylonitrile butadiene styrene (ABS), ethyl-vinyl acetate (EVA), other similar copolymers, other similar, suitable, or conventional thermoplastic materials, and formulations that incorporate any of the aforementioned polymers. Examples of inorganic fillers include talc, calcium carbonate, kaolin clay, magnesium oxide, titanium dioxide, silica, mica, barium sulfate, and other similar, suitable, or conventional materials.
Examples of cross-linking agents include polyurethanes, such as isocyanates, phenolic resins, unsaturated polyesters, epoxy resins, and other similar, suitable, or conventional materials. Combinations of the aforementioned materials are also examples of cross-linking agents. Examples of lubricants include zinc stearate, calcium stearate, esters, amide wax, paraffin wax, ethylene bis-stearamide, and other similar, suitable, or conventional materials. Examples of stabilizers include light stabilizers, tin stabilizers, lead and metal soaps such as barium, cadmium, and zinc, and other similar, suitable, or conventional materials. In addition, examples of process aids include acrylic modifiers and other similar, suitable, or conventional materials. Examples of pigments include titanium dioxide and other similar or suitable white or color additives.
One example of a polyolefin composite used in the present invention is a cellulosic/HDPE material. The composite material may be comprised of at least one cellulosic filler in an amount of about 10% to about 70% by weight, more preferably about 30% to about 50%. Additionally, the composite material may be comprised of HDPE material in an amount of about 10% to about 70% by weight, more preferably about 30% to about 55% by weight. The HDPE material is comprised of HDPE. The HDPE may be of any desired type, and it may have any desired melt index (MI). The HDPE may be incorporated in any desired form, but powder reactor flake form is preferred to facilitate mixing with the cellulosic filler. Optionally, the HDPE material may include other ingredients in addition to the HDPE. For instance, lubricants may be included in the amount of 0% to about 15% by weight of the composite, more preferably about 1% to about 7% by weight of the composite. Examples of lubricants include, but are not limited to, wax, zinc stearate, and other types of stabilizers, e.g., metal soaps. Furthermore, the HDPE material may include at least one inorganic filler, e.g., talc and other mineral fillers, in the amount of 0% to about 25% by weight of the composite, more preferably about 5% to about 20% by weight of the composite. The composite may also optionally include an endothermic or exothermic blowing agent from 0% to about 15% by weight, preferably from 0% to about 6% by weight.
On the other hand, an example of a polyvinyl chloride composite used in the present invention may include at least one cellulosic filler in the amount of about 30% to about 60% by weight, more preferably about 40% to about 50% by weight, and still more preferably about 45% to about 50% by weight. The composite may also include a PVC material in the amount of about 40% to about 70% by weight, more preferably about 50% to about 60% by weight, and still more preferably about 50% to about 55% by weight. The PVC material may include stabilizer(s) in an amount of about 1 to about 10 parts, more preferably about 3 to about 5 parts, per 100 parts of the PVC resin. The lubricant(s) may be present in an amount of about 2 to about 12 parts, more preferably about 4 to about 8 parts, per 100 parts of the PVC resin. Also, process aid(s) may be included in an amount of about 0.5 to about 8 parts, more preferably about 1 to about 3 parts, per 100 parts of the PVC resin. Optionally, at least one inorganic filler may be added in an amount of up to about 10 parts, more preferably up to about 5 parts, per 100 parts of the PVC resin.
As previously mentioned, an example of a cellulosic filler is wood flour. In an exemplary embodiment of the present invention, the wood flour may have a mesh size from about 40 to about 100, preferably from about 40 to about 60. The wood flour may be selected from any desired type of wood including, but not limited to, oak, maple, and pine.
In the exemplary embodiment shown in FIG. 1, the plank 14 and rail 16 are made from the composite material of the present invention. This exemplary embodiment may include at least two of rail 16; however, the second rail 16 is not shown in the figures. The post 12 may be any commercially available fence post and may be generally made from plastic, metal, wood, or any other suitable material. However, the post may be made from the composite material of the present invention as well.
In this exemplary embodiment, plank 14 and rail 16 may be comprised of a HDPE wood foam composite material. Such a composite may be comprised of at least one cellulosic component (e.g., wood flour) in an amount of about 15% to about 55% by weight, more preferably about 30% to about 40%. Additionally, the composite material may be comprised of HDPE material in an amount of about 30% to about 70% by weight, more preferably about 45% to about 55% by weight. The HDPE material is comprised of HDPE. The HDPE may be of any desired type, and it may have any desired melt index (MI). The HDPE may be incorporated in any desired form, but powder reactor flake form is preferred to facilitate mixing with the cellulosic filler.
Optionally, the HDPE material may include other ingredients in addition to the HDPE. For instance, lubricants may be included in the amount of 0% to about 10% by weight of the composite, more preferably about 1% to about 6% by weight of the composite. Examples of lubricants include, but are not limited to, wax, zinc stearate, and other types of stabilizers, e.g., metal soaps. Furthermore, the HDPE material may include at least one inorganic filler, e.g., talc and other mineral fillers, in the amount of 0% to about 20% by weight of the composite, more preferably about 5% to about 15% by weight of the composite. In addition, the plank 14 and rail 16 may include an endothermic or exothermic blowing agent from 0% to about 15% by weight, more preferably from 0% to about 6% by weight. As mentioned, the fence 10 may also only comprise a single component (e.g., such as the plank 14) made from the plastic composite of the present invention and then the remaining components may be commercially available products or products made from other types of materials.
FIGS. 2, 3, and 4 show an alternative embodiment of fence 30, wherein plank 34 is comprised of the plastic composite described above, rail 36 is comprised of a composite 22 having a substrate 24 at least partially embedded in the plastic composite 22, and the post 32 may be any commercially available fence post. In the alternative, the post 32 may be made from the same plastic material used to make plank 34, the plastic material and embedded substrate used to make the rail 36, another plastic composite of the present invention, or any other similar or suitable material. This exemplary embodiment may include at least two of rail 36; however, the second rail 36 is not shown in the figures. It is understood that any component of fence 30 may include a substrate at least partially embedded in the plastic composite. However, for illustration purposes only and, not limitation, the substrate 24 is only shown embedded within rail 36.
In this exemplary embodiment, rail 36 is comprised of a composite material 22 with a perforated metal sheet embedded in the center of rail 36 as described above. The composite material 22 of this alternative embodiment is comprised of at least one cellulosic component in an amount of about 25% to about 65% by weight, more preferably about 40% to about 50%. Additionally, the composite material may be comprised of HDPE material in an amount of about 15% to about 55% by weight, more preferably about 30% to about 40% by weight. The HDPE material is comprised of HDPE. The HDPE may be of any desired type, and it may have any desired melt index (MI). The HDPE may be incorporated in any desired form, but powder reactor flake form is preferred to facilitate mixing with the wood flour filler.
Optionally, the HDPE material may include other ingredients in addition to the HDPE. For instance, lubricants may be included in the amount of 0% to about 15% by weight of the composite, more preferably about 5% to about 10% by weight of the composite. Furthermore, the HDPE material may include at least one inorganic filler, e.g., talc and other mineral fillers, in the amount of 0% to about 25% by weight of the composite, more preferably about 10% to about 20% by weight of the composite.
The plastic composite 22 may cover some or all sides of the substrate 24. FIG. 3 shows a preferred embodiment in which the substrate 24 is covered on all sides by the plastic composite 22. The substrate 24 may be embedded in the plastic composite 22 by any suitable means. For example, the plastic composite 22 may be formed on the substrate 24 such that the substrate 24 becomes embedded in the plastic composite 22. The plastic composite 22 may be formed on the substrate 24 by extrusion, compression molding, injection molding, or any other similar or suitable hot melt process.
The substrate 24 may have any suitable shape and dimensions to provide the desired rail 36 characteristics. In this example, the substrate 24 is a sheet. As shown in FIG. 2, the sheet may have at least one perforation 26. In this type of embodiment, the plastic composite 22 may flow through the aperture(s) 26, thereby locking the substrate 24 in the plastic composite 22. An aperture 26 may have any suitable shape and dimensions. Preferably, an aperture is sufficiently large to allow the passage of the plastic composite 22. In one exemplary embodiment, an aperture 26 is circular in shape and has a diameter of about 0.0625 in. However, it is not intended to limit the aperture to any particular shape or dimensions. Similarly, the spacing between the apertures may be selected to provide the desired rail 36 characteristics.
The substrate 24 may be solid in other embodiments. In such an embodiment, the plastic composite 22 may be formed at least partially around the substrate such that it becomes embedded. An adhesive or any other suitable tie layer may be used to facilitate embedding the substrate in the plastic composite.
The substrate may be made from any material that is suitable for providing the desired fence characteristics. In one exemplary embodiment, the substrate 24 may be made from any material that has more bending strength or rigidity than the plastic composite. In other words, a piece of the material used for the substrate 24 may have a higher bending strength or rigidity than a comparable size piece of the plastic composite 22. In another exemplary embodiment, the substrate 24 may be selected for improving the fastener 38 retention of the rail 36. Metal and metal alloys are examples of materials that are suitable for use as a substrate 24 in the present invention. Examples of metal include steel, aluminum, and other similar or suitable metals and metal alloys.
Fiberglass is another example of a material that may be used as a substrate 24 in the present invention. Still other examples of materials that may be used as a substrate 24 include, but are not limited to, wood, pre-formed wood composites, pre-formed plastic composites (such as, but not limited to, inorganic-filled plastic composites and cellulosic-filled plastic composites), pre-formed plastics, glass, concrete, other types building or construction materials, other similar or suitable materials that have a higher bending strength or rigidity than the plastic composite, and other similar or suitable materials that improve the fastener retention of the resulting rail 36.
FIG. 4 shows fence 30 assembled with rail 36 connected to post 32 and plank 34 connected to rail 36. As shown, rail 36 includes the substrate 26 embedded within composite material 22. Fasteners 38 extend through plank 34 and into rail 16 to preferably engage substrate 26. The size and position of the fasteners 38 as well as the size and position of the apertures in the substrate 26 may be selected such that the fasteners 38 extend though the metal. If the fasteners 38 engage the substrate 26, this may increase the retention of fasteners 38. In addition, the perforated substrate 26 may help to limit creep by the rail 16. For exemplary purposes only, the rail 16 is 3 inches by 1 inch, and the perforated sheet 26 is 0.030 inch by 2.5 inches.
In an exemplary method of making the fence 10 or 30 of the present invention from a cellulosic composite, the cellulosic filler(s) may be dried to a desired moisture content. For example, the cellulosic filler(s) may be dried to about 0.5% to about 3% moisture content by weight, more preferably to about 0.5% to about 1.5% moisture content by weight. However, it is appreciated that the cellulosic filler(s) may have a moisture content less than about 0.5% by weight or greater than about 3% by weight. In addition, it should be recognized that an in-line compounding and extrusion system may be utilized to eliminate a pre-drying step.
Some or all of the composite ingredients may be combined in a mixer prior to introduction into a molding apparatus such as an extruder (which may include a die system), a compression molding apparatus, an injection molding apparatus, or any other similar or suitable molding apparatus. Also, some or all of the ingredients may be separately introduced into the molding apparatus. One example of a mixer is a high intensity mixer such as those made by Littleford Day Inc. or Henschel Mixers America Inc. Another type of a mixer is a low intensity mixer including, but not limited to, a ribbon blender. The type of mixer may be selected to blend the ingredients at desired temperatures. An example of an extruder is a conical, twin screw, counter-rotating extruder with a vent. At least one force feed hopper, crammer, or any other suitable, similar, or conventional apparatus may be used to feed the materials into the extruder. Using a cross-head die, the resulting plastic composite may be formed on the substrate.
The fence 10 or 30 and/or any or all of its components may be manufactured using an in-line extrusion process. In this exemplary embodiment, all of the raw materials except the optional blowing agent and any colorant are premixed before entering the extrusion system. The extrusion system may be comprised of at least one extruder, at least one inline die, and other suitable extrusion equipment. One such extruder is a standard, twin screw conical, CM 80, commercially available from Cincinnati Milacron, Cincinnati, Ohio. As the pre-mixed material is fed into the extruder, the blowing agent and colorant are also fed into it. The materials are heated and forced through an inline die located at the opposite end of the extruder. The die shapes the material into a two-dimensional desired shape.
FIG. 5 shows an example of an in-line manufacturing system 40 that may be used to make an exemplary component of the present invention. In this exemplary embodiment, the plastic composite raw materials 50 are fed from a hopper 42 into an extrusion system 44 that processes the plastic composite. The extrusion system 44 may be comprised of at least one extruder 46, at least one die 48, and other suitable extrusion equipment. The raw materials are mixed and heated in the extruder 46 and then pushed through the die 48.
The die system 48 may include a fold-up die, a calibrator, a sizer, or any other similar or suitable equipment for making extruded products. The resulting product 52 may undergo roll forming, cold forming, hydro forming, and other similar or suitable manufacturing techniques. Also, after exiting the die system, the extruded product may be cooled. For example, the extruded product may be cooled by submersing it in a water bath, passing it through a cooling liquid spray, and/or drying it with compressed gas or cryogenic fluid.

EXAMPLE

An example of a rail 36 having a substrate 24 was made and compared to a similar rail 36 without an inner substrate layer 24. The rail 36 having a substrate 24 was also compared to a pine board. The testing consisted of withdrawing a #8 galvanized deck screw which had been inserted to a depth of 1.25 inches in each type of component to compare fastener retention. The testing demonstrated the component of the present invention exhibited significantly improved fastener retention. The test results are shown below.

COMPONENT (LBS/INCH OF DEPTH)

Rail With Perforated Steel 1065

Rail Without Perforated Steel 867

CCA Treated S.Y. Pine Board 568
Any embodiment of the present invention may include any of the optional or preferred features of the other embodiments of the present invention. The exemplary embodiments herein disclosed are not intended to be exhaustive or to unnecessarily limit the scope of the invention. The exemplary embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. Having shown and described exemplary embodiments of the present invention, those skilled in the art will realize that many variations and modifications may be made to affect the described invention. Many of those variations and modifications will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.

Claims

1. A fence rail comprising:

a substrate; and

a composite layer comprising a plastic and at least one filler, said composite covering said substrate such that all sides of said substrate are coated by said composite layer;

wherein said substrate has a higher bending strength than a comparable size piece of said composite or said substrate is adapted to improve a fastener retention ability of said fence rail.

2. The fence rail of claim 1 wherein said substrate is comprised of metal.

3. The fence rail of claim 1 wherein said substrate is comprised of fiberglass.

4. The fence rail of claim 1 wherein said substrate is a substantially flat sheet.

5. The fence rail of claim 1 wherein said substrate has at least one perforation such that said composite passes through said at least one perforation.

6. The fence rail of claim 1 wherein said plastic comprises polyethylene.

7. The fence rail of claim 1 wherein said at least one filler is selected from the group consisting of cellulosic fillers and inorganic fillers.

8. The fence rail of claim 1 wherein:

said at least one filler comprises cellulosic filler in an amount from about 25% to about 65% by weight of said composite; and

said plastic comprises polyethylene in an amount from about 15% to about 55% by weight of said composite.

9. The fence rail of claim 8 wherein said composite further comprises inorganic filler in an amount less than about 25% by weight of said composite.

10. The fence rail of claim 1 wherein:

said substrate is comprised of a substantially flat sheet of metal having at least one perforation such that said composite passes through said at least one perforation;

11. A fence comprising:

a plurality of spaced-apart posts;

a rail extending between said posts, said rail comprising:

a) a substrate; and

b) a composite layer comprising a plastic and at least one filler, said composite covering said substrate such that all sides of said substrate are coated by said composite layer;

wherein said substrate has a higher bending strength than a comparable size piece of said composite or said substrate is adapted to improve a fastener retention ability of said rail.

12. The fence of claim 11 wherein said substrate is comprised of metal.

13. The fence of claim 11 wherein said substrate is comprised of fiberglass.

14. The fence of claim 11 wherein said substrate has at least one perforation such that said composite passes through said at least one perforation.

15. The fence of claim 11 wherein:

16. The fence of claim 15 wherein said composite further comprises inorganic filler in an amount less than about 25% by weight of said composite.

17. The fence of claim 11 wherein:

18. The fence of claim 11 further comprising at least one plank connected to said rail by a fastener such that said fastener extends through said substrate.

19. A fence comprising:

a plurality of spaced-apart posts;

a rail extending between said posts, said rail comprising:

a) a substrate comprised of a substantially flat sheet of metal having at least one perforation; and

b) a composite layer covering said substrate such that all sides of said substrate are coated by said composite and said composite passes through said at least one perforation, said composite comprising:

i) cellulosic filler in an amount from about 25% to about 65% by weight of said composite; and

ii) plastic in an amount from about 15% to about 55% by weight of said composite; and

a plank connected to said rail, said plank comprised of a composite, said composite comprising:

a) cellulosic filler in an amount from about 15% to about 55% by weight of said composite; and

b) plastic in an amount from about 30% to about 70% by weight of said composite.

20. The fence of claim 19 wherein:

said plank is a picket of said fence; and

said plank is connected to said rail by a fastener such that said fastener extends through said substrate.