Patent Application
20070148429
The present invention relates to tri-extruded composite articles, and more particularly, to a sizing composition for reinforcing fibers used in tri-extruded reinforced composite articles where the sizing composition includes additives to achieve desired physical or structural attributes.
Wood fibers, especially fibers from waste wood generated during the production of dimensional lumber or the milling or shaping of wood substrates, in combination with one or more polymeric adhesives, have long been used in the production of composite materials such as oriented strand board (OSB) and particleboard. OSB products, for example, can be manufactured by combining wood fibers with urea, phenol, and melamine resin binders to form an intermediate product. This intermediate product is then subjected to relatively high pressures and/or temperatures to compress and cure the mixture and obtain the final OSB product. Although this process is generally suitable for forming large planar sheets, it is less suitable for forming composite products that have complex profiles and/or otherwise formed portions.
In addition, wood fiber and strand thickness and length typically utilized in producing OSB products are generally less suitable for products intended for applications in which mechanical forces must be transmitted more uniformly throughout the composite product. Indeed, the variations in the diameter and length of the wood fibers incorporated into the OSB products tend to produce regions of high pressure and low pressure that render such products generally unsuitable for articles subjected to bending stresses.
Particleboard is manufactured using a process similar to that used to manufacture OSB but, rather than using wood fibers or stands, particleboard is manufactured using fine wood particles as its main structural component. The use of conventional binders and/or adhesives similar to those used in the manufacture of OSB typically requires the application of very high pressures and an elevated temperature to compress and cure the mixture to produce the final product. The structural limitations associated with particleboard, particularly its reduced strength relative to corresponding thicknesses of OSB and plywood products, its tendency to absorb water, and its increased density render it unsuitable for many applications, particularly exposed applications or those in which significant loads are anticipated.
Other methods have been developed to utilize wood fiber in making shaped articles having drawn portions, such as pallets, rather than more planar articles such as decking or sheeting. Such pallets typically include a flat support surface with a plurality of projections extending below the support surface for contacting the floor or shelving on which the pallet is placed. Such pallets are typically manufactured from a variety of wood fibers, particularly those typically found in paper mill effluent streams, usually in combination with one or more filler materials, for example clay, and/or longer wood fibers from one or more secondary sources. The wood fibers are typically bonded using one or more thermosetting resins, for example phenolformaldehyde, resorcinol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, urea-furfural and condensed furfuryl alcohol resin and organic polyisocyanates.
The bonding performance of isocyanates can be highly dependent upon the density and porosity of the bonded materials. Therefore, when isocyanates are utilized, a preferred practice is to limit the size and density distribution within the mixture of wood fibers that are being processed into the drawn articles. This limitation can result in an acute disadvantage in systems that obtain waste wood from many different sources. The use of these isocyanate binding agents may also raise environmental and workplace safety issues. These compositions also tend to exhibit only limited moisture protection and do not tend to exhibit uniform strength characteristics throughout their load bearing portions.
Molded pallets and platforms may also incorporate one or more plastic compositions, typically either as a coating applied over a wood or cellulosic fiber matrix or as an additive to a wood pulp slurry. While the products produced by incorporating one or more plastics may exhibit improved moisture resistance, such articles continue to suffer from either the strength limitations referenced above or by requiring an intricate and complex forming process. In some situations, plastic is added only as a coating in the final forming stages of the article, and thus does not tend to impart significant bonding, strength, and other desirable characteristics that can be achieved when appropriate plastic formulations are utilized in composite products as a primary structural component and/or as a bonding agent.
Additionally, the conventional methods which utilize wood fibers in some capacity to form a finished composite article do not tend to utilize the waste wood supply in any substantive manner, with portions of the waste wood typically being incinerated, used as fuel in an electrical cogeneration facility or buried in a landfill. Many of the conventional methods utilize either paper mill sludge as a source for wood fibers or are resigned to being dependent on the arrival of a sufficient raw wood supply which is consistent in the same type of wood utilized previously utilized.
Other efforts to produce composite structural materials incorporating waste wood involves combining the cellulosic fibers from the waste wood with particles of one or more plastics such as high density polyethylene (HDPE) or low density polyethylene (LDPE) to form a composite mixture. The length of fiber or flake and the type of plastic selected are dependent upon the material characteristics desired in the finished product. A coupling agent may be added to the mixture as the cellulosic fibers and the plastic(s) are being blended together, thereby enhancing the intended properties in the finished article.
This composite material mixture may then be deposited onto a mold to form a mat or charge of the composite material on the mold. Depending on the manner in which the composite material is applied to the mold, some control over the fiber orientation within the mold. The composite material mixture is then typically subjected to a combination of heat and pressure sufficient to force the plastic throughout the fibers to fill substantially all voids and interstices.
It is an object of the present invention to provide a reinforced composite article that includes an elongated primary structural frame having a longitudinal recess, a second polymeric composition that fills the longitudinal recess, and a third polymeric composition that forms a capping layer on a major surface of the primary structural frame. The primary structural frame is formed from a first polymeric composition that includes reinforcing fibers at least partially coated with a sizing composition that contains a film forming agent, a coupling agent, a lubricant, one or more additives, a first coupling agent to enhance the interface between the first polymeric composition and the surface of the glass fibers, and a second coupling agent to enhance the interface between the first polymeric composition and the boundary between the primary structural frame and the longitudinal recess when the longitudinal recess contains natural fibers. The additive(s) in the size formulation may be selected to make the reinforcing fiber more compatible with the resin matrix or to provide a mechanical or visual property. Examples of suitable additives include, but are not limited to, fire retardants, UV stabilizers, processing aids, antioxidents, mold inhibiting agents, lubricants, colorants, coupling agents, sealants, friction modifiers, color stabilizers, IR reflectors, smoke suppressors, pigments, biocides, dyes, additives to improve surface feel and/or roughness, and additives to reduce abrasion resistance. Because the additives are added with the size composition directly onto the reinforcement fibers, the additives may be incorporated at a reduced or optimal level. Additionally, the inclusion of additives to the size composition permits for the customization of product-specific sizing compositions tailored to achieve desired physical or structural attributes. Further, the additives may be dispersed substantially evenly throughout the primary structural frame by including the additives as part of the sizing composition.
It is another object of the present invention to provide a high performance reinforcing fiber. The reinforcing fiber is a glass fiber at least partially coated with a sizing composition that contains a film forming agent, a first coupling agent, a lubricant, one or more additives, a first coupling agent to enhance the interface between the first polymeric composition and the surface of the glass fiber, and a second coupling agent to enhance the interface between the first polymeric composition and the surface of natural fibers. The additive(s) in the size formulation may be selected to make the glass fiber more compatible with the resin matrix or to provide a mechanical or visual property. Examples of suitable additives include fire retardants, UV stabilizers, processing aids, antioxidents, mold inhibiting agents, lubricants, colorants, coupling agents, sealants, friction modifiers, color stabilizers, IR reflectors, smoke suppressors, pigments, biocides, dyes, additives to improve surface feel and/or roughness, and additives to reduce abrasion resistance.
It is yet another object of the present invention to provide method of manufacturing a reinforced composite article that includes coextruding a first polymeric composition including reinforcing fibers having thereon a sizing composition that contains one or more additives that include a first coupling agent to enhance the interface between the first polymeric composition and the surface of the glass fibers, and a second coupling agent to enhance the interface between the first polymeric composition and the boundary between the primary structural frame and the longitudinal recess when the longitudinal recess contains natural fibers, a second polymeric composition, and a third polymeric composition to form a composite article. In the reinforced composite article, the first polymeric composition forms a primary structural frame that has a first longitudinal recess, the second polymeric composition substantially fills the first longitudinal recess, and the third polymeric composition forms a surface layer on a major surface of the primary structural frame. The second polymeric composition may include a filler such as wood flour, wood fibers, calcium carbonate, talc, magnesium hydroxide, and gypsum. Examples of suitable additives include, but are not limited to, fire retardants, UV stabilizers, processing aids, antioxidents, mold inhibiting agents, lubricants, colorants, coupling agents, sealants, friction modifiers, color stabilizers, IR reflectors, smoke suppressors, pigments, biocides, dyes, additives to improve surface feel and/or roughness, and additives to reduce abrasion resistance. Because the additives are added with the size composition onto the reinforcement fibers, the additives may be dispersed substantially evenly throughout the primary structural frame. The third polymeric composition may include at least one second additive such as UV stabilizers, color stabilizers, IR reflectors, fire retardants, smoke suppressors, lubricants, pigments, biocides and/or dyes.
It is an advantage of the present invention that the inclusion of additives to the size composition permits for the customization of product-specific sizing compositions tailored to achieve desired physical or structural attributes.
It is another advantage of the present invention that utilizing the reinforcing fibers as a carrier for desired additives may result in an overall improvement in the performance of the products formed from the additive-sized reinforcement fibers.
It is yet another advantage of the present invention that incorporating additives into the size composition and onto the reinforcement fibers may aid the dispersion of the additives substantially evenly throughout the polymer matrix.
It is a further advantage of the present invention that by applying desired additives directly to the reinforcement fibers, the additives can be expected to more effectively enhance the interface between the resin and the surface of the reinforcement fibers.
It is also an advantage of the invention that because the additives are added with the size composition directly onto the reinforcement fiber, they may be incorporated at a reduced or optimal level.
It is a feature of the present invention that the application of desired additives to the reinforcing fiber with the sizing composition may result in a reduction in the amount of wasted additives and manufacturing costs.
It is another feature of the invention that the efficacy of the reinforcing fiber in terms of its inherent reinforcing capability may be enhanced with the inclusion of the additives into a sizing formulation.
The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.
The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. All references cited herein, including published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, or any other references, are each incorporated by reference in their entireties, including all data, tables, figures, and text presented in the cited references.
In the drawings, the thickness of the lines, layers, and regions may be exaggerated for clarity. It is to be noted that like numbers found throughout the figures denote like elements. The terms “size”, “sizing”, and “size composition” may be used interchangeably herein. In addition, the terms “film former” and film forming agent” may be used interchangeably. Further, the terms “composition” and “formulation” may be used interchangeably herein.
It is anticipated that composite articles manufactured according to the invention will be suitable for applications including, for example, residential and commercial building applications, residential and commercial decking; residential and commercial fence and railing systems; docks and slipways; residential and commercial exterior finishing or cladding products; residential interior structural finishing and cladding products, alternatives to dimensional lumber in some applications; and infrastructure products such as highway sound control barriers.
The use and incorporation of glass fibers will tend to improve resistance to moisture uptake, which in turn could enhance resistance to mold and mildew. The increased strength, particularly with regard to materials suitable for residential and commercial decking could allow for increased spans which in turn would reduced the level of supporting structure required to build a structurally equivalent assembly.
With regard to the glass composition itself, the present invention will typically incorporate glass coupling agents and possibly other additives and processes for improving the incorporation and adhesion of the glass fibers within the composite article. The glass fiber may comprise up to about 40 wt. %, but more typically 15-30 wt. %, of one or more elements of the final composite article and may be combined with other elements that are substantially free of glass fibers. This invention also provides methods for glass fiber handling and delivery that allow for improved introduction of discrete glass fibers into abroad range of composite materials during the manufacturing process.
As noted above, composite articles fabricated in accord with the invention, particularly those that incorporate wet fibers (e.g., wet use chopped strand glass fibers (WUCS)) or other components that initially include or subsequently release water may incorporate one or more water scavengers. For example, in the course of preparing a polymeric component with WUCS for subsequent inclusion in a composite article can utilize gypsum particles as a filler that will tend to scavenge the water present in the wet glass fibers. Utilizing this scavenging function of the gypsum filler in one or more of the components used to form the composite article tends to reduce or eliminate the need for subsequent venting or drying that was previously necessary to remove water from the component(s) as steam during the subsequent elevated temperature molding and/or forming operation(s). In this respect, the gypsum filler functions as both a processing aid and as a filler that will tend to increase the bulk of the composite articles and improve their fire resistance.
The invention also encompasses the use of one or more polymer coupling agents to enhance the surface bond between not just the glass and resin, but also in the event that wood fibers or particles are used in combination with glass fibers, the surface bond between adjacent wood fibers or particles. It is anticipated that both recycled, post-consumer, and virgin thermoplastic resins may be used successfully in manufacturing embodiments of the composite articles according to the invention. Further, although the composite articles and the associated methods of manufacture according to the invention are expected to utilize predominately extrusion processes, it is anticipated that some compositions within the scope of the invention would have properties suitable for use in injection molding processes as well and may be suitable for use in combination with premanufactured films, layers, or inserts.
In most instances, it is expected that modified polyolefin polymers will be suitable for use as coupling agents applied to the glass substrate before the fibers are blended with the other components of the composite material. These polymers include, for example, maleic grafted polypropylene, polyethylene and polypropylene-polyethylene copolymers, ethoxylated polypropylene, polyethylene and polypropylene-polyethylene copolymers, and ethylene acrylic functional polypropylene, polyethylene and polypropylene-polyethylene copolymers. These additives, when applied to the glass in aqueous form prior to blending with other components, act as adhesion promoters to improve the mechanical properties of wood plastic composites.
Embodiments of the invention may include the use of glass fibers and maleic anhydride grafted polyethylene and polypropylene polymers in tandem to improve the mechanical properties of wood plastic composites. Exemplary reinforced compositions will include between about 25 wt. % to about 45 wt. % polymer, between about 25 wt. % to about 45 wt. % wood fiber and/or wood flour, and about 5 wt. % to about 40 wt. % fiberglass, preferably WUCS. The coupling agent(s), for example maleic grafted polymer(s), may be used with the fiberglass in weight ratios between about 1:5 and 1:40 relative to each other. Using these components in these formula ratios will tend to improve the effectiveness of the fiberglass reinforcements.
The incorporation of wood fibers, wood flour and/or other organic fibers and fillers will be improved through the use of an appropriate compatibilizer. Exemplary compatibilizers include copolymers that provide a coupling function among various components of the composite material and/or can change the chemical environment of the compositions used to form the composite article that allows the various components to be more easily and/or uniformly dispersed to form a more stable composite. The specific manner in which the compatibilizer functions is not critical, but typically improved coupling functionality relative to conventional coupling agents is preferred.
A compatibilizer (or compatibilizing copolymer) typically represents a copolymerization reaction product of an olefin and at least one other comonomer. It is expected that a range of olefins can be used singly or in combination in practicing the invention including, for example, ethylene, propylene, isomers of butylene, and/or other common olefins of the type widely used in conventional polymerization reactions employing traditional (Zieglar-Natta) catalysts and/or more specific metallocene catalysts.
Useful compatibilizers are those that include a functional comonomer (e.g., a monomer that can be copolymerized with a suitable olefin under conditions suitable for olefin-polymerization) that includes an anhydride functionality. An exemplary functional comonomer is maleic anhydride and its general functional equivalents such as maleic anhydride derivatives such as maleic acid and/or its salts; maleic acid diesters or monoesters, including esters of C1-C4 alcohols, such as, for example, methyl, ethyl, n-propyl, isopropyl, and n-butyl alcohols; itaconic acid; fumaric acid; fumaric acid monoester; and mixtures thereof. Of particular note with regard to the selection of appropriate compatibilizers are maleic anhydride and its monoesters and/or diesters.
Useful compatibilizers also include terpolymers of ethylene (E); maleic anhydride and/or it chemical equivalents; and a third comonomer, X, selected from a group including, for example, vinyl acetate, (meth)acrylic acid, and/or derivatives thereof. Suitable derivatives of (meth)acrylic acid include salts, esters, anhydrides, or other acid derivatives are known to one of ordinary skill in the chemical arts including preferred acid derivatives including, for example, methyl acrylate and/or butyl acrylate.
Compatibilizers may be present in those components of the composite article that incorporate wood and/or other organic materials an amount of about 0.1 to about 10 wt. % based on the total weight of the composition. Preferably the compatibilizer is present in an amount of from about 0.25 wt. % to about 5 wt. %, more preferably in an amount of from about 1 wt. % to about 4 wt. %. As will be appreciated by those skilled in the art, the concentration of compatibilizer necessary to obtain a desired result will be a function of the polymers used, the type of organic material being incorporated, and the particular compatibilizer(s) being utilized.
One or more compatibilizers, particularly those including higher concentrations of the functional comonomer(s), can be blended with other polymeric materials to dilute the concentration of the functionality and thereby provide a blended composition for use in various types of wood composite materials.
As suggested above, a wide variety of cellulosic and other fibrous and/or filler materials may be utilized in the present invention. Cellulosic materials for use in the present invention may be obtained from wood and wood products, such as wood pulp fibers; non-woody paper-making fibers from cotton; recycled paper materials; straws and grasses, such as rice and esparto; canes and reeds, such as bagasse; bamboos; stalks with bast fibers including, for example, jute, flax, kenaf, cannabis, linen and ramie; and leaf fibers, such as abaca and sisal. The cellulosic materials can be used singly or in combination.
Wood and wood products may be especially suitable for inclusion in one or more of the polymeric components of the composite articles according to the invention. Suitable wood sources will typically include softwood sources such as pines, spruces, and firs, and hardwood sources such as oaks, maples, eucalyptuses, poplars, beeches, and aspens. The form of the cellulosic materials from wood sources, particularly waste wood sources, can be incorporated into the polymeric components as one or more of sawdust, wood chips, wood flour and/or wood fibers.
As will be appreciated, in addition to wood products, cellulosic materials obtained from other agricultural residues and/or industrial waste can be incorporated into one or more of the polymeric components used in forming a composite article according to the invention. Examples agricultural residues will include, for example, the residue remaining after harvesting wheat, rice, corn and/or other grain stocks such as straw; corn stalks; rice hulls; wheat; oat; barley and oat chaff; coconut shells; peanut shells; walnut shells; jute; hemp; bagasse; bamboo; flax; and kenaff; and combinations thereof. Additional discussion of these materials and other components that may be incorporated in the composite articles according to the invention may be found in WO 05/080496, published Sep. 1, 2005, the disclosure of which is incorporated by reference in its entirety.
One or more of the polymeric components that comprise a composite article according to the invention, particularly exposed components, may include one or more fire retardants such as magnesium hydroxide, zinc borate, and gypsum (hydrated calcium sulfate). These additives may either be used in a specific region or component, for example, a capstock, as in the case of a multiple extrusion, or as an additive incorporated in a gelcoat, e.g., a typically quick-setting resin used in molding processes for providing an improved surface for the composite. In molding processes, the gelcoat may be the first resin applied to the mold after the mold-release agent, thereby becoming an integral part of the finished composite article.
Alternatively, one or more additives may be distributed throughout the entire product with the various polymeric components having similar or substantially different effective concentrations of the additives depending on the functional results of the additive and the need for that function in the particular polymeric component. For example, UV stabilizers will more likely be concentrated in one or more surface layers while processing aids for foaming agents may be found only in internal reduced density components.
In a further embodiment of the present invention, one or more additives may be applied to the glass fiber with a sizing composition during fiber formation. The application of additives to the glass fiber enhances the glass fiber reinforcements, enabling the production of composite articles having a desired combination of size, strength, appearance, and/or functionality. Conventionally, additives are added in masterbatches, which are inherently wasteful due to losses associated with job start-up, job change, and shut down. By applying desired additives directly onto the glass fibers, which would, in turn, be added directly to the extruder after the extrusion process is stabilized, a higher application efficiency of the additives may be achieved. As a result, the amount of additives that were conventionally wasted may be reduced or even eliminated. Such an increase in application efficiency would reduce manufacturing costs related to any wasted additives. In addition, coupling agents can be expected to more effectively enhance the interface between the resin and the surface of the glass fibers when they are incorporated in the sizing composition.
One perceived advantage of utilizing the glass fiber as a carrier for desired additives includes an overall improvement in the performance of the products formed from the additive-sized glass fibers. In addition, incorporating additives into the size composition and onto the glass fibers may aid in the dispersion of the additives evenly or substantially evenly throughout the polymer matrix as well as in the layer or component of the end product (e.g., the primary structural frame) in which the glass fibers are included. Further, the efficacy of the glass fiber in terms of its inherent reinforcing capability may be enhanced with the inclusion of the additives into the sizing formulation. As a result, it may be easier to optimize the glass fiber content required to achieve a desired level of structural performance. Preferred structural improvements enabled by glass fiber addition include increased load rating and flexural modulus, reduced plastic creep, and better dimensional stability versus temperature.
After the glass fibers are formed, a sizing composition containing additives may be applied by conventional methods such as by application rollers or by spraying the size composition directly onto the fibers. The additives are chosen to achieve selective or desired properties. A suitable size composition according to at least one exemplary embodiment of the present invention may include one or more film forming agents (such as a polyurethane film former, a polyester film former, a polyolefin film former, a modified functionalized polyolefin, and/or an epoxy resin film former), at least one lubricant, and at least one silane coupling agent (such as an aminosilane or methacryloxy silane coupling agent). When needed, a weak acid such as acetic acid, boric acid, metaboric acid, succinic acid, citric acid, formic acid, phosphoric acid, and/or polyacrylic acids may be added to the size composition, such as, for example, to assist in the hydrolysis of the silane coupling agent.
As discussed above, the size composition may include one or more coupling agents. Preferably, the coupling agent is a silane coupling agent. Besides their role of coupling the surface of the reinforcement fibers and the plastic matrix, silanes also function to enhance the adhesion of the polycarboxylic acid component to the glass fibers and to reduce the level of fuzz, or broken fiber filaments, during subsequent processing. Examples of silane coupling agents that may be used in the present size composition may be characterized by the functional groups amino, epoxy, vinyl, methacryloxy, ureido, isocyanato, and azamido. In preferred embodiments, the silane coupling agents include silanes containing one or more nitrogen atoms that have one or more functional groups such as amine (primary, secondary, tertiary, and quarternary), amino, imino, amido, imido, ureido, isocyanato, or azamido.
Suitable silane coupling agents include, but are not limited to, aminosilanes, silane esters, vinyl silanes, methacryloxy silanes, epoxy silanes, sulfur silanes, ureido silanes, and isocyanato silanes. Specific non-limiting examples of silane coupling agents for use in the instant invention include γ-aminopropyltriethoxysilane (A-1100), n-phenyl-γ-aminopropyltrimethoxysilane (Y-9669), n-trimethoxy-silyl-propyl-ethylene-diamine (A-1120), methyl-trichlorosilane (A-154), γ-chloropropyl-trimethoxy-silane (A-143), vinyl-triacetoxy silane (A-188), methyltrimethoxysilane (A-1630), γ-ureidopropyltrimethoxysilane (A-1524). Other examples of suitable silane coupling agents are set forth in Table 1. All of the silane coupling agents identified above and in Table 1 are available commercially from GE Silicones.
In addition, the size composition may include at least one resinous film forming agent. Film formers are agents which create improved adhesion between the glass fibers, which results in improved strand integrity. The improved processing due to the enhanced strand integrity, particularly with respect to material handling and material conveyance, increases the potential viability of utilizing a multiple application chopped strand (“MACS”) product that may be optimized for wood plastic composite applications. The film former acts as a polymeric binding agent to provide additional protection to the reinforcing fibers and improves processability of the glass fibers. Any conventional film forming agent known to those of skill in the art may be utilized in the size composition. Suitable film formers include thermosetting and thermoplastic polymers which promote the adhesion of sizing compositions. For example, film formers for use in the present invention may include polyurethane film formers, epoxy resin film formers, polyolefins, modified polyolefins, functionalized polyolefins, and saturated or unsaturated polyester resin film formers. Specific examples of film formers include, but are not limited to, polyurethane dispersions such as Neoxil 6158 (available from DSM); polyester dispersions such as Neoxil 2106 (available from DSM), Neoxil 9540 (available from DSM), and Neoxil PS 4759 (available from DSM); and epoxy resin dispersions such as PE-412 (available from AOC), NX 9620 (available from DSM), Neoxil 0151 (available from DSM), Neoxil 2762 (DSM), NX 1143 (available from DSM), AD 502 (available from AOC), Epi Rez 5520 (available from Hexion), Epi Rez 3952 (available from Hexion), Witcobond W-290H (available from Chemtura), and Witcobond W-296 (available from Chemtura).
Polyurethane film formers are a desirable class of film formers because they demonstrate good compatibility with polyamide matrices and help to improve the dispersion of glass fiber bundles in the resin melt (e.g., in an extrusion process or an injection molding process) when forming a composite article, which causes a reduction or elimination of defects in the final article that are caused by poor dispersion of the reinforcement fibers (e.g., visual defects, processing breaks, and/or low mechanical properties).
Further, the size composition may include at least one lubricant to facilitate manufacturing. Any suitable lubricant may be used. Non-limiting examples of lubricants suitable for use in the size composition include water-soluble ethyleneglycol stearates (e.g., polyethyleneglycol monostearate, butoxyethyl stearate, polyethylene glycol monooleate, and butoxyethylstearate), ethyleneglycol oleates, ethoxylated fatty amines, glycerine, emulsified mineral oils, and organopolysiloxane emulsions. Other examples of lubricants include alkyl imidazoline derivatives (e.g., cationic softener Conc. Flakes, which has a solids content of approximately 90% and is available commercially from Th. Goldschmidt AG), stearic ethanolamide, sold under the trade designation Lubesize K-12 (AOC), and a polyethyleneimine polyamide salt at 50% active solids commercially available from Cognis under the trade name Emery 6760.
As discussed above, the size composition may also contain one or more additives to achieve selective properties in the end product. For example, the additive may be selected to make the glass fiber more compatible with the resin matrix or to provide a mechanical or visual property. As will be appreciated, the additives may be included in the sizing composition in amounts sufficient to provide an acceptable or desired range of a particular attribute caused by that additive. Examples of additives include, but are not limited to, fire retardants, UV stabilizers, processing aids, antioxidents, mold inhibiting agents, lubricants, colorants, coupling agents, sealants, friction modifiers, color stabilizers, infrared (IR) reflectors, fire retardants, smoke suppressors, pigments, biocides, dyes, additives to improve surface feel and/or abrasion resistance, and additives to reduce roughness. Because the additives are applied with the size composition directly onto the glass fiber, the additives may be incorporated into the size composition at a reduced or optimal level. Further, incorporating the additives as part of the sizing composition applied to the glass fibers permits the additives to be evenly or substantially evenly dispersed throughout the primary structural frame. Additionally, the inclusion of additives to the size composition permits for the customization of product-specific sizing compositions tailored to achieve desired physical or structural attributes.
It is to be noted that the exclusion of coupling agents from the size composition would be deleterious in terms of the structural performance of the end product. As a result, it is preferred that two coupling agents are included in the sizing composition. The first coupling agent is chosen to make the glass fiber compatible with the polymer resin and to enhance the interface between the polymeric composition and the surface of the glass fibers. The first coupling agent may be a coupling agent that is typically present in a conventional size formulation. The selection of the second coupling agent is made to best suit the cellulosic or natural fibers, and, as such, is not a typical component of a generic conventional size composition for glass fibers. In particular, the second coupling agent is included to enhance the interface between the first polymeric composition and the boundary between the primary structural frame and the longitudinal recess when the longitudinal recess contains the cellulosic or natural fibers. One benefit of including a coupling agent for natural fibers such wood is that it provides a way to enhance the interface between the structural frame and the longitudinal recess, where the wood fibers or wood flour would be present.
Other coupling agents may be present depending on the desired application and individual components of the composite product. The coupling agents may be selected from the coupling agents described above with respect to the sizing composition, including, but not limited to, those coupling agents set forth in Table 1. The first coupling agent may be present on the glass fiber in an amount from about 1.5 to about 2.5% by weight of the total composition of the structural frame and the second coupling agent may be present on the glass fiber in an amount from about 0.5 to about 1.0% by weight of the total composition of the structural frame.
The balance of the size composition is composed of water. In particular, water may be added to dilute the aqueous sizing composition to a viscosity that is suitable for its application to glass fibers. The size composition may be made by combining the separate components (excluding water) in a container. Water is then added in an amount to achieve the appropriate concentration and control the mix of solids to achieve the appropriate or desired concentration.
One issue relating to the use of fiber reinforcement in compression, extrusion or injection molded materials is the distribution of the reinforcement within the final article, or within one or more components of a composite article, necessary to achieve acceptable mechanical, thermal and impact performance. With fiberglass reinforcement, the strength improvements tend to be proportional to the glass content with a typical reinforced part containing between about 15 to about 60% by volume in the final part.
Those skilled in the art appreciate that in order to achieve a generally uniform distribution of the fiberglass reinforcement, particularly at higher loadings, it is preferred that the fiberglass meet certain geometric and chemical criteria. These criteria include, for example, the configuration of the fiberglass with bundle forms being preferred for the resulting flow properties, the glass bundle tex must be selected and maintained within a range necessary to achieve a desired aesthetic appearance, e.g., little or no fiber prints apparent on the surface of the part. Bundle tex relates to the size of the fiber bundle and is provided in units of weight divided by length, typically in grams/kilometer. The fiberglass bundles should exhibit sufficient cohesiveness to retain the bundle configuration during the necessary processing, e.g., good “bundle integrity,” and any size or binder compositions incorporated with the fiberglass reinforcement should exhibit good compatibility with the primary matrix resin or blend of resins.
A variety of size compositions are known to those skilled in the art, many of which include one or more silanes, for example A-1100 aminosilane, A-174 methacryloxysilane, A-187 epoxy functional silane and A-171 vinylsilane. The film former component of the size composition should be one that will not result in undue “blocking,” e.g., the large scale sticking together or agglomeration of fibers subsequent to the drying step, while at the same time proving sufficient bundle integrity for subsequent process steps, and exhibiting sufficient compatibility with the resin matrix. Additional discussion of exemplary size compositions may be found, for example, in U.S. Pat. No. 6,025,073 to Piret, the contents of which are hereby incorporated by reference in its entirety.
Various known combinations of urethanes and acrylics are expected to be suitable for practicing the invention and other combinations of unsaturated polyesters, epoxies, acrylics and modified vinyl acetates are expected to be suitable as well. Other additives may include lubricants, including both cationic lubricants, such as Emery 6760 L, and nonionic lubricants, such as PEG 400 monooleate and mono isostearate, strand stiffeners, for example N-vinylpyrolidone, catalysts and other conventional additives.
The fiberglass bundle tex can be controlled by splitting the primary strand as many times as necessary on the chopping cot. The bundle integrity may be controlled to some extent by applying the appropriate film former(s) to the fiber using conventional techniques and by applying enough energy, particularly in the form of radiofrequency (RF) energy, to convert the aqueous film former composition to dry film on the fiber surfaces that shows a reduced blocking tendency. A combination of a polyurethane dispersion, for example Witcobond W290H, Hydrosize U1-01 or Hydrosize U2-01, and a urethaneacrylic alloy such as Witcobond A-100 can be used to form a suitable size composition.
As will be appreciated by those skilled in the art, composite articles fabricated according to the invention may also include one or more reduced density components, particularly for filling one or more voids defined by other components, for example a structural component. These reduced density materials may be prepared using a variety of methods, depending in part on the properties desired for the final component. Such methods include, for example, producing foams through chemical reactions and/or the reducing the pressure under which the polymeric component is maintained to allow one or more blowing agents incorporated in the polymeric composition to expand and form a foam. Such methods may be used in conjunction with one or more light weight filler materials including, for example, exfoliated minerals and inorganics and/or microspheres.
Illustrated in
As suggested in
If desired, the initial form 110a may then be subjected to additional heating and/or forming operations in unit 112 to modify the initial form an produce an intermediate form 110b having a more complex cross-sectional profile. An example of a cross-section of an intermediate form 110b along plane B-B is illustrated in
Although as illustrated in
Illustrated in
If desired, the initial form 210a may then be subjected to additional heating and/or forming operations in unit 212 to modify the initial form an produce an intermediate form 210b having a more complex cross-sectional profile. An example of an intermediate form 210b is illustrated in
Depending on the intended use and the composition of the primary material used to form the intermediate form 210b and the additional layer or film 218, the composite structure of the intermediate form and the additional layer or film can be then be subjected to additional heating and/or forming operations in unit 214 to modify the intermediate form as detailed above and/or increase the attachment between the primary material and the secondary material of the additional layer to produce a composite final form 210c. A cross-sectional example of a final form 210c is shown in
Illustrated in
As illustrated in
Illustrated in
As illustrated in
To the extent that the desired result can be achieved with something other than a solid mass of the first material, the recesses or voids can be left empty (not shown) or filled with a coextruded material 316 which may or may not expand or foam to some degree after extrusion. Particularly for flooring or decking applications, it is anticipated that filled embodiments may reduce sound transmission and/or heat transmission while possibly improving fastener retention and/or improving rigidity.
As illustrated in
For example, by utilizing a capping or surface layer 318 that does not need to perform a predominate structural function, the invention provides for more efficient use of expensive additives, for example UV stabilizers, that provide no appreciable benefit when incorporated into material(s) that form the bulk of the product. As will be appreciated by those of ordinary skill in the art, the same will hold true for other additives incorporated to improve other specific properties or parameters including, for example, abrasion resistance, fire retardancy, mold resistance, surface feel and/or roughness, wear properties as well as color retention. Similarly, by avoiding the need to blend the primary material to achieve suitable appearance and surface properties, the primary material may be modified to enhance its structural performance including, for example, one or more of strength, flexibility, hardness and thermal expansion.
It is anticipated that one application for which products manufactured in accord with the invention will be especially suited will be composite deck boards. As will be appreciated, there remains a need for composite deck boards that exhibit improved performance in one or more areas including, for example, one or more of span ratings, appearance, weatherability, thermal performance and durability. As detailed above, although a range of configurations according to the invention may achieve one or more of these improvements, it is anticipated that multi-component deck flooring products corresponding to embodiments of the invention manufactured using, for example an exemplary tri-extrusion process as detailed above will incorporate one or more of the desired improvements.
Conventional composite deck boards are typically manufactured by extruding a thermoplastic resin, such as one or more of polyethylene, polypropylene and PVC, that has been blended with wood flour and/or fibers, lubricants, and additives in an effort to lower production costs and/or improve the composite board properties. In most instances, therefore, such conventional processes produce composite boards manufactured completely from a single composition in which any additives and fillers present in the composition are dispersed substantially uniformly throughout the entire thickness and width of the resulting composite board. Accordingly, in order to obtain sufficient concentrations of UV stabilizers or other bulk additives in those portions of the composite board where they are actually required, the manufacturer must add quantities of a suitable (an relatively expensive) UV stabilizer or stabilizers that are essentially, if not totally, wasted in the interior regions of the composite board.
Although other manufacturing processes may be utilized, as detailed above it is anticipated that a three-component structure manufactured utilizing at least one coextrusion process will be particularly suitable. Depending on the various components and proportions used to manufacture the respective materials, processes and dyes used, it is expected that exemplary products manufactured and/or configured in accord with the invention, the products may include deck planking, balusters and/or capping or “capstock” materials.
As will also be appreciated, depending on the intended application of the product, recesses and voids formed in the primary structural frame may be filled with a foaming or other light weight composition to produce a composite article having a substantially “solid” cross section. If foam is utilized as the filling material, it will typically be produced through the use of one or more blowing agents, for example CO2 or N2 that is both non-toxic and non-combustible. By using such blowing agents, or a compatible blowing agent system, the continued presence of the blowing agent in the foam will not present additional concerns or reduce the performance of the composite product.
The foamable or filled core composition will preferably include one or more colorants, dyes or pigments so that if a cross section of the composite article is exposed by, for example, sawing a composite decking plank, the various components will cooperate to provide a fairly uniform and “solid” appearance. This uniform appearance will typically require at least the structural component(s) and the filling or core components having similar final colors in order to avoid highlighting the presence of different materials. The capping or cover layer, however, is relatively thin and will not tend to contribute as significantly to the cross-sectional appearance.
With regard to texture, if a foamable mixture is used in the core component, it may be compounded with nucleation materials and/or expanded under conditions that will produce foams having a relatively small cell size to avoid highlighting the presence of different materials through distinct surface textures. Further, if a foamed material is utilized and will not be completed enclosed, it is preferable that the foamable composition be selected so that a skin layer will form at the exposed surface and thereby avoid the appearance of open cells and more closely match the texture and appearance of the surrounding structures. Similarly, if the core component is formed from a lightweight filled composition, the size and coloration of the fill materials should be selected so that the core component does not exhibit an “aggregate” appearance with distinct discontinuous and continuous phases when viewed in cross-section.
Because the fill or core material need not provide a significant portion of the structural strength of the composite articles according to embodiments of the invention, the core material may be formulated using less expensive (and accordingly weaker) polymeric compositions such as foams and more highly filled materials. Similarly, because in some embodiments the fill or core material will be exposed only when the composite article is cut, the core material may be formulated with lower loadings (if any) of reinforcing materials and will typically include lower concentrations (if any) of those additives intended primarily for improving appearance, for example, color fastness, scuff resistance and finish texture.
In certain embodiments of composite articles according to the invention, an increased contribution to the overall strength of the composite article can be achieved by incorporating reinforcing fibers, for example WUCS, into the foamable or filled composition. Including reinforcing fibers in the core or fill component can also improve the apparent uniformity between the reinforced structural components and the core component when viewed in cross-section.
The capping, finishing or final layer 318 applied to the primary structure will typically incorporate higher concentrations of certain additives, for example UV stabilizers, wear resistors, anti-skid materials and/or other antioxidants relative to the other compositions incorporated in the final product. Similarly, as suggested above material 314 used to form the primary structural frame can be reinforced with higher levels of glass fibers that those incorporated into the other compositions to modify one or more mechanical performance parameters to obtain a product that better satisfies the requirements of a particular application.
Illustrated in
As illustrated in
As discussed above, the capping, finishing or final layer 318 may be milled, embossed or otherwise machined or processed to produce a textured surface to provide a more natural, distinctive or safer surface as desired. In addition to the mechanical processing, the capping layer 318 may be fabricated from a composition to which one or more additives including wood, clay, other fillers, different polymers, reinforcing fibers and/or colorants have been added. The combination of the additives and the surface processing may be utilized to produce composite articles having, for example, a more natural wood appearance, e.g., by simulating the coloring, grain and/or texture of a natural board, or to provide an appearance that mimics other natural or conventional construction materials, for example, stone or aggregate. It is anticipated that capping layers that result in composite articles more effectively and realistically simulating natural or widely accepted construction materials would increase their level of acceptance and use in the building and decorating trades.
Alternatively, the combination of the additives and surface processing may be utilized to produce composite articles having a distinctive and decorative that does not obviously suggest any natural surface. For example, the combination of the additives and surface processing may be selected to duplicate the appearance of conventional wood plastic composites so that it will tend to blend with and/or complement existing installations and thereby be more suitable for repair or replacement applications.
As noted above, in addition to the particular combination of components used to form the surface coating, the coating can also be subjected to one or more forms of mechanical processing during and/or after formation. For example, the surface coating or capping layer may be subjected to embossing, pressing, stamping, planing, milling or other processing in order to add texture to the capping layer that simulates a natural “wood grain” feel.
Embossing, for example, may be configured as a continuous process in which the composite article exiting an extruder die is fed through a set of pinch rollers, at least one of which includes a raised pattern that will be imprinted on to the surface to which the roller is applied. Pressing, for example, may comprise a batch process in which a series of composite articles, for example decking boards, are sequentially loaded and pressed in a textured mold under temperature and pressure conditions suitable for transferring the mold texture to one or more surfaces of the boards. Planing may be configured as a batch or a continuous process in which at least portions of the capping layer are removed by rotating or oscillating blades. Although in conventional woodworking, planing is a process typically utilized for smoothing and/or leveling a board surface, in this instance it may be adapted for selectively removing portions of the capping layer to cut a desired texture or pattern into the processed surface. The texturing process(es) utilized for producing a desired surface appearance and texture in the final composite product will, to some degree, guide the selection of appropriate capping layer compositions and the thickness of the capping layer, particularly if the process involves removing a portion of the capping layer.
Conventional foamed boards tend to exhibit inferior mechanical properties than solid boards of similar dimensions. Some attempts have been made to improve the mechanical properties of foamed boards by incorporating glass fibers, but such attempts have not produced compositions in which the glass fibers are both present in sufficient quantities and exhibit sufficient adhesion to the polymeric resin(s) to achieve the desired improvement in the mechanical properties. As noted above, composite articles according to an embodiment of the invention utilize WUCS treated with an appropriate size composition in the foamed core to improve mechanical properties. Because WUCS production does not require the drying and/or curing steps utilized in the production of conventional fiber reinforcements, WUCS may provide both economic and performance advantages over conventional fibers in the production of both foamed articles and composite articles incorporating foamed components.
Further, with regard to the composite articles fabricated according to the various embodiments of the invention, it is anticipated that the coextrusion process will tend to reduce undesirable interactions between components that may be separated in two or more compositions that will, in turn, be utilized to form a final composite structure. For example, one problem often associated with the use of additives in wood/plastic composite materials is the absorption of the additives by the wood flour, thereby lowering the effectiveness of a particular concentration of the additive(s). Thus, by separating at least certain of the additives into components that do not include wood flour, or have a reduced wood flour component, it is expected that improvements will be noted in the effectiveness of a given additive package in such a component. This, in turn, will allow the quantity of the additives to be reduced and/or increase the effectiveness of a defined additive package intended, for example, to increase resistance to UV degradation.
It is also anticipated that the multi-extrusion process detailed above will provide certain advantages in attempting to improve both material usage and turn costs. For example, the composition used for forming the primary structural frame could incorporate higher concentrations of reinforcing fibers, for example, WUCS, for improving mechanical properties while allowing the capping and core layers to remain relatively free of reinforcing fibers. These improvements in material strength can be leveraged to reduce the quantity of material necessary to obtain a target strength and/or rigidity, typically by utilizing a more complex cross-section, as illustrated in, for example,
Again, as noted above, the primary structural frame will typically define a plurality of recesses, channels or cavities that may, in turn, be filled using one or more less expensive materials that will tend to exhibit correspondingly less robust mechanical properties. Although, as noted above, the spaces defined by the primary structural frame may be left unfilled, it is anticipated that most private individuals and contractors reviewing their options in terms of composite decking materials will have at least some preference for those articles, whether solid or composite, that exhibit a sufficiently “solid” appearance. Accordingly, the use of one or more filling materials including, for example, foamed polymer(s), polymer/wood compositions with higher wood flour concentrations and/or combinations of two or more compositions to fill any significant voids in the structural component will be preferred.
Although, as detailed above composite boards according to the invention are anticipated to be particularly useful in exterior decking applications and may be provided in a range of configurations such as planks, balusters and capping trim in a variety of lengths, widths and thicknesses. The improved durability, dimensional uniformity and appearance may also allow for other applications including, for example, window and door framing. Indeed, depending on the particular materials, configuration and application, composite articles according to the invention may be approved for structural applications, such as some framing, particularly in non-load bearing applications.
Although exemplary, non-limiting embodiments of the invention have been described in detail hereinabove, it should be understood that many variations and/or modifications of the basic inventive concepts herein taught, which may appear to those skilled in the art, may still fall within the spirit and scope of the example embodiments of the invention as defined in the appended claims.
A fourth embodiment according to the invention may be prepared without incorporating any wood particles in any of the polymeric components that make up the composite article. For example, in a composite article incorporating a capstock, the polymeric material from which the capstock is fabricated will typically be a filled and additive-modified polymer that includes one or more additives that would be expected to provide improved wear and color fastness characteristics. The second or intermediate section would typically be a glass fiber-reinforced polymeric material having sufficient strength and stiffness and a configuration that will allow this section or component to serve as the structural skeleton, i.e., of the composite article. The third element, which may also be referred to as a core or filler element, will typically include one or more reduced density materials, particularly one or more foamed polymeric materials or light weight fill material. By avoiding the use of wood fibers or flour, the resulting composite according to the fourth embodiment will tend to exhibit improvements in those parameters affected by the nature and characteristics of the wood products and/or byproducts relative to corresponding composite articles that do incorporate wood or other organic fiber material.
By avoiding the use of wood or other organic materials, the resulting composite article will tend to exhibit improved resistance to certain problems associated with organic materials including, for example, mold, mildew, bacteria or insects, without the need for similar quantities of biocides or other preventative treatments. It is also anticipated that the elimination or reduction of wood products, particularly in the capstock or surface layer would have benefits in respect any related manufacturing processes. In particular, the capacity of equipment necessary for storing, conditioning, processing, transporting and/or incorporating wood or other organic materials into the polymeric compositions may be significantly reduced. Reductions in the number and/or capacity of such equipment will tend to reduce costs and avoid potential hazards associated with the dust generated by and/or solvents used for processing the wood or other organic materials.
Further, although it is anticipated that in most instances the structural component formed from the first polymeric composition and/or the surface or finish layer will form the exterior of the composite article, in some instances the second polymeric composition may form the bulk of the article. As illustrated in
As illustrated in FIGS. 9B-E, a full or partial finish layer 318 and a one or more reinforcing elements 314 can be incorporated into the primary foam composition. As will be appreciated by those skilled in the art the relative quantity and configuration of the reinforcing component 314 can be used to increase horizontal and/or vertical strength and may be incorporated as relatively simple,
A fifth embodiment of a composite article according to the invention provides improved fire retarding performance. Although the basic product configuration may be similar to that described above in connection with the fourth embodiment (no wood flour, fiber, or particles present), the fifth embodiment will utilize a capstock composition that includes higher filling levels and/or concentrations of one or more fire and flame retardant and/or smoke suppressing materials including, for example, various organic halogen compounds, phosphorus compounds, antimony trioxide, alumina trihydrate, magnesium hydroxide, zinc borate, metal chelates incorporating Fe, Co, Ni, Cu, or Zn (particularly in combination with Al(OH)3 and Mg(OH)2), and various intumescent compounds.
By incorporating higher levels of these fire and flame retardants and/or suppressants, for example, magnesium hydroxide (MgOH2), in the capstock layer, in combination with the internal structural component(s), particularly those that are reinforced with higher levels of glass fibers, a composite article may be fabricated that exhibits improved resistance to burn through and/or sagging in the event of a fire. In such a composite article, the capstock layer acts as an ablative or energy absorbing layer while the reinforced structural component or substrate supports the capstock and provides an improved physical barrier. Composite articles fabricated according to this embodiment are expected to have particular utility in fire-rated building products.
A sixth embodiment of a composite article according to the invention can provide an improved and/or more natural surface appearance. In this embodiment, during fabrication of the composite article a combination of polymers, which may be provided in one or more forms including fiber, flake, particle and pellet, are introduced into the capstock layer or the surface layer. Depending on the composition, form, the apparatus used to achieve the incorporation or addition and the various additives such as fillers and colorants incorporated in the polymer(s) being added, a range of surface effects can be produced. For example, adding polymer(s) having a darker color than the base polymer composition can produce variegated surface finishes that can more realistically mimic the grain of natural wood products.
Similarly, incorporating polymers having various colors and/or fillers can be used to create a wide range of distinct and highly customizable finishes that may or may not mimic natural materials. This ability to provide different finishes and looks through this technique may increase the use of these materials by designers and stylists in the manner in which other existing synthetic materials such as CORIAN® and/or synthetic stone products such as SILESTONE® are specified and employed. Accordingly, composite articles according to this embodiment of the invention may be acceptable for uses and applications ranging from exterior decking to interior and exterior finishing systems.
A seventh embodiment of a composite article according to the invention can utilize a more substantial foamed component while still providing an improved and/or more natural surface appearance. In this embodiment, the majority of the composite article comprises a polymeric foam that may incorporate minor internal structural components and/or a capping or finish layer intended to provide improved appearance and/or durability. In lieu of the capping or finish layer, as the polymeric foam is extruded a combination of polymers, which may be provided in one or more forms including fiber, flake, particle and pellet, may be introduced into an outer portion of the foam. Depending on the composition, form, the apparatus used to achieve the incorporation or addition and the various additives such as fillers and colorants incorporated in the polymer(s) being added, a range of surface effects can be produced. For example, adding streaks or stripes of polymer composition(s) having a darker color than the base polymer composition can produce variegated surface finishes that can more realistically mimic the grain of natural wood products.
Further, as noted above, in addition to the particular combination of materials introduced into the outer layer of the foam, the foam and/or any incorporated materials can also be subjected to one or more forms of mechanical processing during and/or after formation. For example, the surface coating or capping layer may be subjected to embossing, pressing, stamping, planing, milling or other processing in order to add texture to the capping layer that simulates a natural “wood grain” feel as suggested in
An eighth embodiment of a composite article according to the invention provides improved resistance to biological degradation in function or appearance. Although the basic product configuration may be similar to that described above in connection with the previous embodiments, the eighth embodiment will incorporate one or more compositions, particularly those that are or may become exposed to the environment, that include higher filling levels and/or concentrations of one or more biocidal agents or biocides. Typically the selected biocides will be those having demonstrated efficacy against organisms that would tend to decompose the wood and/or polymeric components of the composite article or simply those organisms that will tend to blemish or degrade the appearance of the affected surfaces in some manner, e.g., mildew or black algae forming on wetted surfaces.
The biocides may be introduced as liquids or particles including, for example, relatively insoluble polymeric nanoparticles which can be introduced into the compositions as suspensions, emulsions or dry powders. Those biocides distributed or otherwise introduced into one or more of the compositions may also act as a diluent to improve the volumetric distribution of the biocide(s) as the small particle or nanoparticles containing the biocide(s) and/or other additives, throughout the composite. Providing a plurality of biocides on separate insoluble nanoparticles can more effectively maintain separation between the active compounds and, in appropriate instances, can improve the stability of the biocide(s) and prolong their biocidal effectiveness by reducing mutual negative interactions between the biocide(s) and/or other components.
The biocides may be selected in consideration of their compatibility with the primary polymeric component(s), the polymers used in forming the nanoparticles (if any), the compatibility of the biocides, the solubility characteristics of the biocide(s) in the composition, other characteristics of the biocide including, for example, porosity, release rate, and toxicity; and complications (if any) that the use of such a biocide or combination of biocides would introduce into the manufacture of the composite articles. If nanoparticles are utilized, as a general rule the more highly branched polymers will tend to be more useful in forming less dense and more porous polymers that will, in turn, exhibit higher biocide release rates than particles forms form predominately linear polymers. Accordingly, polymers that are particularly useful for forming nanoparticles for distributing biocides throughout a WPC include, but are not limited to, polyvinylpyridine, polymethacrylate, polystyrene, polyvinylpyridine/styrene copolymers, polyesters, polyethylene, polypropylene, polyvinylchloride and blends thereof. Further, each of these homopolymers may be blended with acrylic acid or other suitable compound.
The biocide(s) may also be selected according to the target organism(s) to which exposure would be reasonably expected in the intended application of the composite article, stability at the temperature ranges and pH ranges anticipated during manufacture and/or use. As used herein, the term “biocide” is intended to encompass any compound or substance that tends to kill or inhibit the growth of one or more microorganisms and/or invertebrates, including, for example, molds, slime molds, fungi, bacteria, insects and arachnids. Accordingly, insecticides, fungicides and bactericides are each an example of a biocide. More specific classes of biocides include, but are not limited to, chlorinated hydrocarbons, organometallics, halogen-releasing compounds, metallic salts, organic sulfur compounds, compounds and phenolics. More specific examples of biocidal compounds include, without limitation, copper naphthenate, copper oxide, zinc naphthenate, quaternary ammonium salts, pentachlorophenol, tebuconazole (TEB), chlorothalonil (CTL), chlorpyrifos, isothiazolones, propiconazole, other triazoles, pyrethroids, and other insecticides, imidichloprid and oxine copper. Additional inorganic preservatives and biocides include, for example, boric acid, sodium borate salts, zinc borate, copper salts, zinc salts and combinations and mixtures thereof.
As will be appreciated by those skilled in the art, the polymeric nanoparticle technique may be used for distributing additives other than biocides. In particular, certain flame retardants and/or smoke suppressants may be introduced into one or more of the compositions used to form the composite articles by incorporating the active ingredient into a suitably porous nanoparticle. For example, fire retarding chemicals, water repellants, colorants, UV inhibitors and adhesive catalysts can be incorporated into such particles. As will be appreciated, the nature of the additive and the primary polymeric component(s) of the WPC will determine which polymers are most suitable for the incorporation and distribution of such additives. For example, flame suppressing compounds such as borax/boric acid, guanylurea phosphate-boric acid, dicyandiamide phosphoric acid formaldehyde and diethyl-N,N-bis(2-hydroxyethyl)aminomethyl phosphate may be incorporated into nanoparticles formed from polyvinylpyridine or polyvinylchloride.
Testing
The impact of the addition of WUCS material in WPC articles was examined in a series of sample articles. In a first trial, various quantities of WUCS (¼ inch (6.4 mm) chop, 16 μm fiber, E-glass having a nominal 10% moisture content) or DUCS as reinforcing fibers (“RF”) were combined with wood flour (“WF”), (fresh 40 mesh pine) and a polymer, either polypropylene (PP) having a melt flow index (“MFI”) of about 5 or HDPE, to produce various compositions that were formed into plank boards. Ten samples where then cut from each of the plank boards for testing. Additional samples were prepared using 1-2% of a coupling agent selected from POLYBOND® 3029 (maleated HDPE) (available from Crompton) and FUSABOND® 100D (maleated LLPE) (available from DuPont). The samples cut from the plank boards formed from the various compositions were then tested according to ASTM 709 to example their relative flexural properties. The sample compositions prepared in the first trial were compounded according to TABLE 2.
The sample compositions prepared in the second trial were compounded according to TABLE 3.
1WUCS - ¼ inch chop, 10% moisture
2DUCS - ¼ inch chop, dry and 4% lubricant
The data generated from the samples showed that relative to the control samples (those with no added WUCS or DUCS), the addition of 20% and 30% WUCS resulted in 34% and 45% percent increases in the Young's Modulus of the samples. Similarly, the combination of 20% DUCS and at least 1% coupling agent in the HDPE samples achieved as much as a 75% increase in the Young's Modulus when compared with the control samples. It is expected that additional development of the size composition provided on the WUCS and/or the use of coupling agents would tend to reduce the difference in the Young's Modulus between the WUCS and DUCS compositions.
Although the invention has been described in the context of particular composite articles and component materials, those skilled in the art will appreciate that the inventive methods and structures may be adapted for a wider range of polymeric compositions, additives, structures and applications. Example embodiments of the invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not as limiting the invention to the embodiments disclosed. Accordingly, it will be understood by those skilled in the art that various changes in form and details of the disclosed compositions, articles and methods may be made without departing from the spirit and scope of the invention as set forth in the following claims. In particular, those skilled in the art will appreciate that various compositions and structures described with respect to one embodiment may be combined with complementary compositions and structures described with respect to a different embodiment to form a new composite article in accord with the disclosed invention.
This application is a Continuation-in-Part of U.S. patent application Ser. No. 11/311,749 entitled “Tri-Extruded WUCS Glass Fiber Reinforced Plastic Composite Articles And Methods For Making Such Articles” filed Dec. 19, 2005, the entire content of which is expressly incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11311749 | Dec 2005 | US |
| Child | 11638800 | Dec 2006 | US |
