Thermoplastic composite building product having continuous fiber reinforcement

Abstract

The present invention relates to a decking product, such as railing, fencing, posts and decking, made in part from commingled continuous filaments of glass fibers and polymeric fibers. The commingled fibers can be consolidated into a composite reinforcement or final profile, and can be used in the form of bulk molding compound pellets. The consolidation of the commingled fibers into a composite reinforcement can be made in-situ, during in-line extrusion of the final end product, profile, or extrudate, or prepared as a tape or rod and later incorporated into an off-line extrusion of final product. The bulk molding pellets can be used solely or diluted with an addition of polymeric material for extrusion, co-extrusion, or compression molding, for example.

Description

FIELD OF THE INVENTION

The present invention relates to a process for providing thermoplastic composite building products having fiber reinforcement, and more particularly, to the use of a consolidated form of the commingled continuous filaments of glass fibers and polymeric fibers as continuous or bulk reinforcement in building products, such as decking, fencing, railing and posts.

BACKGROUND OF THE INVENTION

Most fence and rail materials are made of either traditional lumber or thermoplastics. Typical plastics in these applications are PVC (polyvinyl chloride) and polyethylene. PVC typically does not have the strength and rigidity of wood and lumber and therefore, the rail for the fence and railing needs a steel or aluminum reinforcement channel inside the rail. These metal reinforcements are prone to corrosion attack, and lose strength in long-term endurance tests. There is also a thermal expansion problem associated with the dark color of thermoplastic products. Dark color fencing rails made out of PVC or other polymeric materials often exhibit bowing due to differences in expansion and contraction between the two different sides of the product upon exposure of sunlight. Since the dark color absorbs heat more readily on the sun-facing side of the product, the resultant uneven heat buildup causes the rail to deform. An additional problem is the lack of long-term stiffness of polymeric products. It has limited the rail span between the posts to lengths less than traditional lumber rails.

Also, synthetic decks, whether composed of plastic or wood-plastic composite materials, do not fully satisfy market needs.

Wood-plastic composite decking planks are produced by extrusion, and extrusion processes have various limitations. Extrusion is often followed by an embossing roll to create a wood grain surface. The quality of such wood grains is often not particularly high. Furthermore, the wood-plastic composite deck planks are heavy, since the wood composite has a low modulus and flexural strength, which needs a thick wall to compensate for these lower strength levels. In addition, the wood-plastic composite deck does not have color fastness; it changes color from natural or gray to silver-gray over time, in a non-uniform manner when exposed to the outdoor environment.

As noted above, there is another class of synthetic deck planks available, namely the PVC profile decks. Such decks are produced by profile extrusion. In this type of production, it is often difficult to use an embossing roll to create the wood grain texture in a uniform nature on the deck surface. The pressure imposed by the embossing roll often cannot provide a uniform force, because the surface of a hollow and three-dimensional panel responds in a non-uniform manner to the particular force. As result, a “real wood” grain emulated surface is particularly difficult to achieve. The PVC profile deck also has a significant thermal expansion coefficient; installation requires care in order to accommodate the expansion and contraction of changes in temperature. In this regard, the dark color deck panel materials have not been practical, since the heat build-up on the surface, and the unwanted thermal expansion that results, is more pronounced for darker colored panels. Regarding color fastness, the darker color PVC is superior to wood-plastic composites, but still has the tendency to lose its original color to a visible degree. Furthermore, PVC has a tendency to become brittle with aging upon outdoor exposure to the elements, particularly UV radiation, resulting in a loss of its impact strength.

The present invention serves to correct the shortcomings noted above. The building products produced in accordance with the present invention have superior resistance to color fading, possess superior cold impact strength, have, in certain embodiments, a well-defined wood grain surface, and are light-weight.

One of the further objectives of the present invention is the production of a high strength plastic alternative to the traditional wrought iron or aluminum ornamental rail and fence. Metal fences and rails are constantly under the threat of corrosive attack, and need periodic painting. To date, there have not been any non-composite products with the necessary performance properties and aesthetic appearance comparable to these metal products. In that sense, there have been very few successful thermoplastic composite products in the market.

Some of the recent teachings for producing reinforced polymeric articles include Branca, U.S. 2004/0048055; Baker, U.S. 2003/0082338, and one of the parents to this application, Jo et al., U.S. 2003/0096090; Hassman, U.S. Pat. No. 3,983,688; Stucky, U.S. Pat. No. 6,344,268; Jambois, U.S. Pat. No. 6,197,412; Junell, U.S. Pat. No. 5,967,498, and Tecton Products, Innovative Composite Pultrusion Solutions commercial products, all cited in Applicants' parent applications and hereby incorporated herein by reference.

The present invention discloses thermoplastic composite products that resemble wrought iron, and wrought aluminum alternatives, but are maintenance-free, kink-free, light weight and perform as well as wrought metal products.

An additional objective is to make the dark color thermoplastic post and rail fence (e.g., split post and rails) by providing a fiberglass reinforcement which stabilizes the uneven contraction and expansion of outdoor building products, in spite of different heat buildup on the surfaces of such products.

A further objective of the present invention is to provide a non-metallic heavy duty rail and fence systems for use in industrial and commercial applications. The metallic railing in an industrial atmosphere is often exposed to chemical gases or acids and is prone to corrosive attack. The integrity of the industrial railing is critical for the safety of those in the workplace. A thermoplastic railing or decking system that is strengthened by reinforcing tapes or rods of fiberglass/thermoplastic polymer composite would provide superior strength and rigidity to its metal counterparts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a deck construction using the preferred composite;

FIGS. 2 and 3 are front perspective views of alternative deck constructions;

FIG. 4 is a front partial view of a fence or railing construction using the preferred composite;

FIG. 5 is a frontal view of a post and rail fence;

FIGS. 1-13 are cross-sectional views of a fence construction using the preferred composite building materials of this invention; and

FIG. 14 is a front partial view of an alternative post and rail fence.

SUMMARY OF THE INVENTION

In a first embodiment, the present invention provides a thermoplastic composite decking material including a molded thermoplastic composite profile made substantially from a bulk molding compound which is, in turn, made substantially from a co-mingled group of glass fibers and consolidated thermoplastic fibers, which form a matrix around the glass fibers. The thermoplastic fibers used to make the bulk molding compound are selected from the group consisting essentially of polyethylene, polypropylene, and (thermoplastic) polyester.

In a further embodiment of this invention, a polymer composite fencing or railing material is provided, which includes a composite reinforcement comprising filaments of fibers substantially oriented in at least a first direction substantially continuously along the entire length of said fencing or railing material, and disposed within a thermoplastic matrix. Disposed substantially over and in direct contact with the composite reinforcements is a capstock polymeric material. The fencing or railing material is resistant to heat deformation and corrosion.

In still a further embodiment of the present invention, a process of making a building component is provided which includes the steps of co-mingling continuous glass and polymeric fibers wherein the polymeric fibers are selected from the group comprising polyethylene, polypropylene, and polyester; consolidating said co-mingled glass and polymeric fibers into a reinforcement; and disposing a polymeric layer at least partially over and in bonding contact with said reinforcement, said polymeric layer forming the profile for said building component.

In yet another embodiment of the present invention, a process of making a building component is provided which includes the steps of co-mingling continuous glass and polymeric fibers, wherein the polymeric fibers are selected from the group comprising polyethylene, polypropylene, and polyester, forming said co-mingled, continuous glass and polymeric fibers into a bulk molding compound; and compression molding said bulk molding compound into a building component profile.

The present invention relates to a process for providing thermoplastic composite building materials, such as railings, posts, and decking profiles with bulk molding compounds and/or continuous fiber reinforcement. Such products can be formed by consolidating commingled continuous filaments of glass fibers and polymeric fibers for use as a reinforcement. The consolidation of commingled fibers into composite reinforcement may be made in-situ during in-line extrusion of the final end product extrudate, or, alternatively, by pre-preparing as a tape or rod and incorporated the tape or rod by way of an off-line extrusion into a final product. In either case, the reinforcement materials of the present invention are, preferably, incorporated through a cross-head die into the polymer extrudate. In this way, the matrix polymer can encapsulate the inside and outside surface of the hollow profile product.

Another production process contemplated by this invention is to pass these commingled fibers through a pultrusion die, followed by an overlay extrusion of a cap stock polymer using a separate extruder, all in-line. In this case, the capstock polymer covers only the outside surface. The commingled fibers are heated prior to entering into the series of forming dies where they are consolidated. In a further embodiment, a helical winding machine may be added in order to enhance the strength in the hoop direction before the die entrance.

A preferred material for use in the present invention is commercially available Twintex™ composite tapes, supplied by the Saint-Gobain Corporation. The materials are present in various forms, such as commingled roving and fabrics (uni-directional, or multi-axial woven fabric or tapes). The commingled roving can be consolidated through a pultrusion die into a thermoplastic composite tape or rod. It therefore may contain glass fibers dispersed uniformly and substantially completely along the longitudinal direction. The polymeric fiber that becomes the consolidation matrix may be either polyethylene (PE), polypropylene (PP) or polyesters (PBT or PET). The functional need of the end product and extrusion process will determine the fiberglass contact in the Twintex™ material and the volume of the consolidated reinforcement. A “standard” material contains about 40%-75% glass fiber content.

Although polyethylene and polypropylene Twintex™ tapes were used in the testing of the present invention, any fibrous polymeric material would be acceptable for a commingling with glass fiber, as long as it is capable of being fiberized and made compatible to the intended matrix polymers.

A further aspect of the present invention relates to the compatibility of the commingled polymeric fiber material with the matrix or capstock polymer of the final extrusion product. These materials need adhesion with each other in order to be effective, since they are, desirably, bonded or adhered to each other as shown in FIGS. 6-13, for example. Accordingly, there is little need for additional adhesive or surface treatment to effect this bond. In the testing of the present invention, a polyethylene-glass fiber Twintex™ reinforcement/HMPE polymer, polypropylene-glass fiber Twintex™ reinforcement/HMPE polymer, polyethylene-glass fiber Twintex™ reinforcement/polyethylene polymer, and polypropylene glass fiber Twintex™ reinforcement/polyethylene polymer were used. The combinations of the polymers of the composite reinforcement and the base polymers are numerous, and may be customized in order to meet the needs of the final product performance requirements.

The Twintex™ composite reinforcement allows for the base polymeric material with a higher impact in both cold and ambient temperatures, lower heat expansion coefficient, higher tensile and flexural strength, as well as higher rigidity. These Twintex™ reinforcements (rods, tapes, or fabrics) are embedded into strategic locations of the basic polymeric material, for example.

In a further preferred embodiment of the present invention, a hybrid of Twintex™ filaments with carbon fibers may be utilized, with the combination providing for higher stiffness and for easier material handling, as well as providing for a lighter weight product.

Some of the materials of the present invention may be manufactured by a pultrusion process, the mechanics of which are familiar to those of skill in the art. The process utilizes continuous Twintex™ fibers (roving or yarn), and other fiber as necessary, in order to process uniaxially reinforced profiles with exceptional longitudinal strength. Modification of the basic process allows for the incorporation of transverse reinforcements. Important components of the pultrusion process are: (1) heating, wherein the thermoplastic fibers are melted, and (2) the consolidation and shape forming at the tooling die, in which relatively high pressure is involved.

In a further preferred embodiment, the commingled, continuous filaments of glass fibers and polymeric fibers include from about 40%-80% glass fiber content. These commingled, continuous filaments may further include carbon fibers and/or aramid fibers. Furthermore, a bulk molding compound may be made out of the commingled, continuous filaments of glass fibers and polymeric fibers. This bulk molding compound may be compression molded into particular building products, such as fence, rail, post, and deck materials. The commingled, continuous filaments may be added through, e.g., a helical winding machine.

In a further preferred embodiment of the present invention, the bulk molding compound includes from about 20%-80% glass fiber content, or is diluted with an addition of polymeric pellets to a glass fiber content of 10%-20% in the final product, with a glass fiber content of about 15% preferred. The thermal expansion and contraction of the composite building material can be controlled by the use of the bulk molding compound.

Wood-plastic composite panels commercially available have a stiffness of about 100,000 PSI. In order to match that stiffness, the present inventors incorporated one half inch to one inch long fiberglass of 10% at minimum with a profile height of about 1.25 to 1.5 inches. These dimensions will result in the composite material having a flexural modulus of about 400,000 PSI or higher. In a preferred embodiment, polymeric materials, specifically polypropylene copolymers with a melt index of about ten and higher, and formulated with a UV stabilizer and colorant, were tested. Note that other polymeric materials may be used for the purposes of the present invention, so long as such materials have an adequate melt index. Measurement of melt flow index was described in ASTM D1238. By incorporating fiberglass in the formulation by means of a bulk molding compound, the thermal expansion and contraction was reduced so that the dark brown color was no longer present. The thermal coefficient of linear expansion was reduced by more than ⅙, to about 1×10⁻⁵ inch/inch/° F. for the polypropylene copolymer.

In reference to the figures, FIGS. 1-3 demonstrate differing ways by which the decking panels and ties may be fastened to the substructure. In FIG. 2, screw fasteners 121 on the top of composite 120 provide the fastening function, while pins 122 act as spacers. The composites 110 and 130, as shown in FIGS. 1 and 3 respectively, rely on a concealed fastener 114 with pin 111, which is formulated to key into the side hole 112 or 131 of composite panels 110 and 130. The concealed fastener 114 can be screwed into the substructure joist by screw 113. The concealed fasteners, such as screw 113, are also desirable for tiles.

Note that the preferred process for achieving the construction of the present invention is compression molding. The molding process provides a wood grain pattern of high quality. In operation, a fiberglass bulk molding compound is processed through a specially designed plasticator, and the billet is shuttled to a compression mold, and pressed. Note further that the plasticator is merely one type of compounding extruder equipped with a screw, designed to process the fiberglass in the bulk molding compound without breaking the fiberglass. Panel lengths produced by the compression molding process may range up to about 20 feet. The compression molding enables the surface of the panels to have customized patterns, as well as slip resistance called for by various industry codes.

Thus, the present invention relates to any walking panels or planks which have incorporated fiberglass of at least about ½ inch long, at about 10% to 40% by weight into a polymeric material of a melt index higher than e.g., about 2, in order to improve the impact strength for both “under room” and cold temperatures. Walking panels or planks with these characteristics may be made into any suitable custom colors, particularly dark colors, and serve to meet relevant building codes, performance criteria, deflection and creep resistance. Furthermore, a quality grain structure is achieved on the surface of the walking panels or planks, thereby controlling slip resistance.

The fiberglass component of the present invention may be chopped fiberglass, hybridized with other modulus enhancing fibers. In a further preferred embodiment, the walking panels or planks may have incorporated mold-in spacers, such as pin 122, for ease of installation. Furthermore, the panels or planks of the present invention may be constructed of fiberglass bulk molding compound, using a compression molding process having a concealed fastener; such materials will make cutting easier by a power driven saw or other related device.

With reference to FIGS. 4 through 14 thereof, a picket and railing construction 100, a post and rail 200 and fence 300 will now be described. Turning to FIG. 1, this partial post and rail construction includes rails 10 and 20, connected by balusters 11. Note the cross-sections 12 and 13 of rails 10 and 20 include Twintex™ rods 14 and 15.

In FIG. 5, partial post and rail construction 200 includes rails 30 and 40 connected by post 50. Note the cross sections 16 and 17 of rails 30 and 40 and cross section 18 of post 50 include Twintex™ rods 19, 20 and 21, respectively.

With reference to FIGS. 6 through 8, cross sections 12, 16 and 13 corresponding to rails 10, 30 and 20 respectively are represented, with related Twintex™ rods 14, 19 and 15 as shown.

Similarly, in FIGS. 9-13, cross sections of various rails are displayed (60-64, respectively) along with Twintex™ rods (65-69, respectively).

Twintex™ may also be manufactured as a bulk molding compound (BMC) with fibers having a length of from about 3/16 inch to 2 inches. These long fibers may be processed through an extruder with a die that is specifically designed for processing of long fiber reinforced plastics. These BMC compounds can be diluted with other polymeric pellets depending on the need of processability, functional demand, or cost reduction.

In a further preferred embodiment of the present invention, a rail of more than an eight foot span between the two posts, on a sixteen foot length encompassing two sections with, e.g., three posts with a Twintex™ reinforcement, is provided. The use of a hybrid reinforcement of Twintex™ commingled fiber and other reinforcement fibers, such as carbon fiber and/or aramid fibers is also possible.

Thus, the bulk molding compounds used for purposes of the present invention may be employed for compression molding into building products including fence, rail, post, deck, etc.

While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art. The present invention relates, in part, to a consolidated form of the commingled continuous filaments of glass fibers and polymeric fibers. The consolidation of the commingled fibers into composite reinforcement can be used in a continuous form or bulk molding compound pellets. The consolidation of the commingled fibers into composites can be made in-situ during in-line extrusion of the final end product extrudate, or prepared as a tape or rod and incorporated into an off-line extrusion of final product. The bulk molding pellets are used solely, or diluted with an addition of polymeric material, for mono or co-extrusion or compression molding.

The appended claims and this invention, generally, should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention.

Claims

1. A thermoplastic composite decking material comprising: a molded thermoplastic composite profile made substantially from a bulk molding compound containing commingled glass fibers and consolidated thermoplastic fibers, wherein the thermoplastic fibers used to make said bulk molding compound are selected from the group consisting essentially of polyethylene, polypropylene, and polyester.

2. The decking material of claim 1, further comprising a wood grain.

3. The decking material of claim 2 wherein said wood grain is slip resistant.

4. The decking material of claim 1, wherein said glass fibers are substantially at least one half inch in length.

5. The decking material of claim 1, wherein said glass fibers comprise about 10-40 wt. % of said decking material.

6. The decking material of claim 1, wherein said decking material comprises a UV stabilizer and exhibits a custom color.

7. The decking material of claim 6, wherein said custom color is a dark color.

8. The decking material of claim 1, wherein the bulk molding compound includes about 20%-80% glass fiber content, or is diluted with an addition of polymeric pellets to a glass fiber content of 10%-20% in the final product.

9. The decking material of claim 8, wherein the thermal expansion and contraction of said decking product is controlled by the use of said bulk molding compound.

10. The decking material of claim 9, wherein said decking material is a walking panel or plank, incorporating a molded-in spacer or spacer hole.

11. A polymer composite fencing or railing material comprising: a composite reinforcement comprising filaments of fibers substantially oriented in at least a first direction substantially continuously along the entire length of said fencing or railing material, and disposed within a thermoplastic matrix; and a capstock polymeric material disposed substantially over and in direct contact with said composite reinforcement; said fencing or railing material being resistant to heat deformation and corrosion.

12. The fencing or railing material of claim 11 wherein at least said capstock has a dark color.

13. The fencing or railing material of claim 12 wherein said heat deformation resistance includes resistance to bowing due to expansion and contraction of said fencing or railing material when exposed to sunlight.

14. The fencing or railing material of claim 13 wherein said composite reinforcement and said capstock are observably discrete portions of said fencing or railing material.

15. The fencing or railing material of claim 11, wherein said composite reinforcement comprises about 20 wt. % fiber content.

16. The fencing or railing material of claim 15 wherein said fibers comprise one or more of: glass, aramid, or carbon fibers.

17. The fencing or railing material of claim 11 wherein said fibers comprise continuous glass filaments, said thermoplastic matrix comprises polypropylene, and said capstock comprises high molecular weight polyethylene (HMPE).

18. The fencing or railing material of claim 11 in which the fencing or railing material is in the form of a fence, rail, post, or fencing or railing component.

19. The fencing or railing material of claim 11 further comprising a secondary group of fibers oriented in a second direction.

20. A polymer composite fencing component comprising: a composite reinforcement comprising continuous filaments of high strength fibers oriented substantially in at least a first longitudinal direction within a thermoplastic matrix; and a thermoplastic capstock polymeric material, which is itself adherent to the thermoplastic of said composite reinforcement, said capstock polymeric material disposed substantially over and in contact with said composite reinforcement; said fencing component being resistant to corrosion and heat deformation due to exposure to sunlight.

21. The fencing component of claim 20 wherein said composite reinforcement comprises one or more of: roving, fabric or tape.

22. The fencing component of claim 21 wherein said fabric comprises a uni-directional, multi-axial or woven material.

23. The fencing component of claim 20 wherein said composite reinforcement comprises a pultrusion.

24. The fencing component of claim 20 wherein said polymeric matrix comprises polypropylene, said fibers comprise continuous glass filaments, and said capstock comprises high molecular weight polyethylene (HMPE).

25. The fencing component of claim 20 wherein said component has a dark color and a span of at least about 8 feet.

26. A polymer composite fencing component comprising: a composite reinforcement comprising continuous glass filaments of fibers substantially oriented in at least a first direction within a pultruded thermoplastic polymeric matrix, said composite reinforcement having a higher tensile strength than aluminum; and a thermoplastic capstock polymeric material having a dark color disposed substantially over and bonded directly to said composite reinforcement; said fencing component being corrosion resistant to chemical gasses or acids and resistant to bowing due to expansion and contraction of said fencing or railing material upon exposure to sunlight.

27. The fencing component of claim 26 wherein said fibers are oriented in substantially only said first direction for substantially the entire length of said fencing or railing material.

28. The fencing component of claim 26 wherein said capstock is directly bonded to said composite reinforcement without additional adhesive or surface treatment.

29. A substantially maintenance free polymer composite ornamental rail or fence component comprising: a thermoplastic matrix composite comprising high strength glass filaments disposed substantially continuously along the entire length of said rail or fence component; and a thermoplastic capstock polymeric material having a dark color disposed substantially over and in direct contact with said composite reinforcement, said rail or fence component being substantially stabilized when exposed to uneven contraction and expansion forces, despite a difference in heat buildup on its surface due to sunlight.

30. The component of claim 29 wherein said polymer of said polymeric matrix composite and said capstock both contain the same thermoplastic resin.

31. The component of claim 29 wherein said composite is a pultrusion.

32. A process of making a building component comprising: (a) commingling continuous glass and polymeric fibers, wherein said polymeric fibers are selected from the group comprising polyethylene, polypropylene, and polyester; (b) consolidating said commingled glass and polymeric fibers into a reinforcement; and (c) disposing a polymeric layer at least partially over and in bonding contact with said reinforcement, said polymeric layer forming the profile for said fencing or railing component.

33. The process of claim 32, wherein said disposing step (c) comprises extruding said polymeric layer over said reinforcement.

34. The process of claim 32 wherein said consolidating step (b) comprises pultruding said commingled glass and polymeric fibers.

35. A process of making a fencing or railing component comprising: (a) commingling continuous glass and polymeric fibers, wherein said polymeric fibers are selected from the group comprising polyethylene, polypropylene, and polyester; (b) forming said commingled continuous glass and polymeric fibers into a bulk molding compound; and (c) compression molding said bulk molding compound into a fencing or railing component profile.