US20050271889A1 - Variegated composites and related methods of manufacture - Google Patents

Abstract

Embodiments of the invention include a composite. The composite includes a crystalline polymer, a plurality of wood fibers blended with the crystalline polymer, an outer surface, and an amorphous polymer visible on the outer surface. The amorphous polymer has a first color and the blend of the crystalline polymer and the plurality of wood fibers has a second color different from the first color. The invention also includes a method of manufacturing the wood-plastic composites such that one polymer is shifted in the composite relative to the other polymer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation-in-part application of U.S. patent application Ser. No. 10/862,448, filed Jun. 8, 2004, by Blair Dolinar for VARIEGATED COMPOSITES AND RELATED METHODS OF MANUFACTURING, the entirety of which is incorporated herein by reference.
DESCRIPTION OF THE INVENTION
• 1. Field of the Invention
• The invention is directed to variegated wood-plastic composites and methods of manufacturing the same. For example, the surfaces of the wood-plastic composites may be variegated by varying the polymer composition of the wood-plastic composite. The invention also includes a method of manufacturing the wood-plastic composites such that one polymer is shifted in the composite relative to the other polymer.
• 2. Background of the Invention
• Wooden components are commonly used in manufacturing decks and related assemblies. Wooden components includes strings of wood fibers having various colors (e.g., rings on trees) that give the surface of the wooden component a streaked appearance. The streaked appearance imparts an aesthetically pleasing look and feel to the deck component. One disadvantage of using wooden components, however, is that the wood may be susceptible to rotting, weather, insects, and/or wear and tear, and may require the acquisition and processing of wood which may involve environmentally unfriendly processing techniques, such as the clear cutting of forests and the use of hazardous chemicals.
• A more environmentally friendly alternative to using wooden components in manufacturing decks and related assemblies is to use a wood-plastic composite made of crystalline polymers. Examples of suitable wood-plastic composites made of crystalline polymers and related methods of manufacture are disclosed in co-owned U.S. Pat. Nos. 5,851,469 and 6,527,532, co-pending and co-owned U.S. patent application Ser. No. 10/292,672 filed Nov. 12, 2002, and co-pending and co-owned U.S. patent application Ser. No. 10/668,368 filed Sep. 24, 2003, the entirety of all of which are incorporated herein by reference.
• Wood-plastic composites made of crystalline polymers, however, tend to have solid one color surfaces. This is at least partially due to the sharp melting point temperatures of crystalline polymers and the tendency of crystalline polymers to easily blend together. Thus, even if a plurality of crystalline polymers having a plurality of different colors are used to manufacture a wood-plastic composites, the plurality of different colors will blend together in the manufacturing process and the composite will emerge having a surface with one solid color. In any case, the resultant composite does not have a streaked appearance.
SUMMARY OF THE INVENTION
• An exemplary embodiment of the invention includes a composite. The composite comprises a crystalline polymer, a plurality of wood fibers blended with the crystalline polymer, an outer surface, and an amorphous polymer visible on the outer surface. The amorphous polymer has a first color and the blend of the crystalline polymer and the plurality of wood fibers has a second color different from the first color.
• In various embodiments, the invention may include one or more of the following aspects: the crystalline polymer may be at least one of polypropylene and polyethylene; the amorphous polymer may be a styrenic polymer; the outer surface may include streaks of the first color; the amorphous polymer may have a melting temperature that is substantially the same as a melting temperature of the crystalline polymer; the outer surface may be variegated; a first portion of the outer surface may have the first color and a second portion of the outer surface may have the second color; another amorphous polymer visible on the outer surface; the another amorphous polymer may have a third color different from the first color and the second color; the composite may be at least one of a building material, a decking material, and a decking board; a colorant may be blended with one of the crystalline polymer and the amorphous polymer.
• Another embodiment of the invention includes a composite. The composite may include a first polymer, a plurality of wood fibers blended with the first polymer, an outer surface, and a second polymer configured to resist blending with the first polymer. The composite may be manufactured such that the second polymer is deliberately visible on the outer surface. The blend of the first polymer and the plurality of wood fibers may have a first color and the second polymer may have a second color different from the first color. The second polymer may not be substantially soluble in the first polymer.
• In various embodiments, the invention may include one or more of the following aspects: the first polymer may be at least one of polypropylene and polyethylene; the second polymer may be a styrenic polymer; the outer surface may include streaks of the second color; the first polymer may have a melting temperature that is substantially the same as a melting temperature of the second polymer; the outer surface may be variegated; a first portion of the outer surface may have the first color and a second portion of the outer surface has the second color; a third polymer may be configured to resist blending with the first polymer; the composite may be manufactured such that the third polymer is deliberately visible on the outer surface; the third polymer may have a third color different from the first color and the second color; the composite may be at least one of a building material, a decking material, and a decking board; a colorant blended with one of the first polymer and the second polymer.
• A further embodiment of the invention may include a method of manufacturing a wood-plastic composite. The method may include providing a crystalline polymer, providing a plurality of wood fibers, providing an amorphous polymer, melting the crystalline polymer, melting the amorphous polymer, mixing the amorphous polymer with the crystalline polymer and the plurality of wood fibers to form a feed, and forming a profile body from the feed, the profile body including an outer surface evincing a first color and a second color different from the first color.
• In various embodiments, the invention may include one or more of the following aspects: forming streaks of the first color on the outer surface; forming streaks of the amorphous polymer on the outer surface; shifting the amorphous polymer towards the outer surface; variegating the outer surface; providing at least one of a single screw extruder and a double screw extruder; the step of extruding may include extruding the feed via the at least one of the single-screw extruder and the double screw extruder; the step of mixing may include forming the first color from the amorphous polymer and forming the second color from a blend of the crystalline polymer and the plurality of wood fibers; providing another amorphous polymer; melting the another amorphous polymer; mixing the another amorphous polymer with the amorphous polymer, the crystalline polymer, and the plurality of wood fibers; the step of extruding may include forming the profile body such that the outer surface evinces a third color different from the first color and the second color; providing a core; the step of forming the profile body may include forming the profile body around at least a portion of the core; providing a colorant; blending the colorant with one of the crystalline polymer and the amorphous polymer.
• Yet another embodiment of the invention may include a method of manufacturing a wood-plastic composite. The method may include providing a first polymer, providing a plurality of wood fibers, providing a second polymer not substantially soluble in the first polymer, melting the first polymer, melting the second polymer, mixing the second polymer with the first polymer and the plurality of wood fibers to form a feed, and forming a profile body from the feed, the profile body including an outer surface deliberately evincing a first color and a second color different from the first color.
• In various embodiments, the invention may include one or more of the following aspects: forming streaks of the first color on the outer surface; forming streaks of the first polymer on the outer surface; shifting the first polymer towards the outer surface; variegating the outer surface; providing at least one of a single screw extruder and a double screw extruder; the step of extruding may include extruding the feed via the at least one of the single-screw extruder and the double screw extruder; the step of mixing may include forming the first color from the first polymer and forming the second color from a blend of the second polymer and the plurality of wood fibers; providing a third polymer not substantially soluble in the first polymer; melting the third polymer; mixing the third polymer with the first polymer, the second polymer, and the plurality of wood fibers; the step of extruding may include forming the profile body such that the outer surface deliberately evinces a third color different from the first color and the second color; providing a core; the step of forming the profile body may include forming the profile body around at least a portion of the core; providing a colorant; blending the colorant with one of the first polymer and the second polymer.
• A yet further embodiment of the invention may include a method of manufacturing a wood-plastic composite. The method may include providing a first polymer, a plurality of wood fibers, a second polymer not substantially soluble in the first polymer, and an additive, melting the first polymer and the second polymer, blending the additive with the second polymer to form a blend, mixing the blend with the first polymer and the plurality of wood fibers to form a feed, forming a profile body with an outer surface from the feed, and shifting the blend towards the outer surface such that at least a portion of the blend is visible on the outer surface.
• In various embodiments, the invention may include one or more of the following aspects: the additive may be one or more of a pigment, a mold inhibitor, and a mildew inhibitor; the blend may substantially cover an entire side of the profile body; the additive may not be blended with either of the first polymer or the wood fibers; the additive may be soluble in the second polymer and not be soluble in the first polymer.
• Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
• It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
• The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.
• FIG. 1 is a perspective view of a composite according to an embodiment of the invention.
• FIG. 2A is a schematic view of the composite ofFIG. 1.
• FIG. 2B is a top schematic view of a composite according to another embodiment of the invention.
• FIG. 2C is a top schematic view of a composite according to a further embodiment of the invention.
• FIG. 3A is a side schematic view of the composite ofFIG. 1.
• FIG. 3B is a side schematic view of a composite according to yet another embodiment of the invention.
• FIG. 3C is a side schematic view of a composite according to still another embodiment of the invention.
• FIG. 4A is a schematic view of a process of manufacturing the composite ofFIG. 1.
• FIG. 4B is a schematic view of a process of manufacturing a composite according to a yet further embodiment of the invention.
• FIG. 4C is a schematic view of a process of manufacturing a composite according to still another embodiment of the invention.
• FIG. 4D is a schematic view of a process of manufacturing a composite according to a still further embodiment of the invention.
• FIG. 4E is a schematic view of a side feeder used in the process ofFIG. 4D.
DESCRIPTION OF THE EMBODIMENTS
• Reference will now be made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
• An exemplary embodiment of the invention includes a composite. As shown in FIGS.1,2A-2C, and3A-3C, composite1 may include afirst polymer2, a plurality ofwood fibers3 blended withfirst polymer2 to form ablend4, anouter surface5, and asecond polymer6 configured to resist blending with first polymer2 (e.g.,second polymer6 is not substantially soluble in first polymer2).Second polymer6 may be visible onouter surface5.Blend4 offirst polymer2 andwood fibers3 may have a first color andsecond polymer6 may have a second color different from the first color.
• Composite1 may be used as a decking component or any other suitable building material. For example, as shown inFIG. 1,composite1 may be used as a decking board, railing, railing post, and/or decking beam. In another example, composite1 may be used to construct any portions of homes, walkways, shelters, and/or any other desirable structure.
• Composite1 may include afirst polymer2 which may be acrystalline polymer2.Crystalline polymer2 is preferably at least one of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polypropylene (PP). The polypropylene may be a homo- and/or a co-polymer polypropylene. However, any crystalline polymer may be used, such as one or more polyamides (PA), nylons, polyoxymethylenes, polybutylene terephthalates (PBT), polyethylene terephthalates (PET), and/or acetals.Crystalline polymer2 may have any suitable size, shape, and/or configuration to be melted, mixed withwood fibers3, and/or extruded into a dimensionally stable profile.Crystalline polymer2 may have any suitable size, shape, and/or configuration to be used in any of the apparatuses or methods disclosed in co-owned U.S. Pat. Nos. 5,851,469 and 6,527,532, co-pending and co-owned U.S. patent application Ser. No. 10/292,672 filed Nov. 12, 2002, and co-pending and co-owned U.S. patent application Ser. No. 10/668,368 filed Sep. 24, 2003, the entirety of all of which are incorporated herein by reference. For example,crystalline polymer2 may be in the form of a pellet, a flake, a film, and/or a scrap form. In another example,crystalline polymer2 may range in size from reactor powder having a diameter of about 0.01650 inches to pieces of plastic having dimensions (e.g., length, width, height, depth, and/or diameter) between about 1 inch and about 100 feet. More typically, however,crystalline polymer2 is film scrap having dimensions (e.g., length, width, height, depth, and/or diameter) between about 0.0787 inches and 0.25 inches.
• Composite1 may include asecond polymer6 which may be anamorphous polymer6, a polycarbonate (PC), apolymer6 that has a higher shear viscosity thanfirst polymer2 and/orcrystalline polymer2, and/or apolymer6 configured to mix with but resist blending withfirst polymer2 and/orcrystalline polymer2. A polycarbonate is a crystalline polymer that may be used as asecond polymer6 because it may have desirable properties relative to other crystalline polymers that may be used asfirst polymers2. For example, PC may char while other crystalline polymers may burn. In another example, PC may have a sufficiently higher shear viscosity relative to other crystalline polymers. In various embodiments, using a PC assecond polymer6 in the apparatuses and methods disclosed herein will provide the same results (e.g., a composite1 with a variegatedouter surface5 and/or streaks16) as the use of anamorphous polymer6. Accordingly, PC may be used interchangeably withamorphous polymer6 in any of the embodiments set forth herein.
• Amorphous polymer6 is preferably a styrenic polymer such as polystrene (PS). However, any amorphous polymer may be used incomposite1, such as one or more of Impact PS, polymethylmethacrylates (PMMA), polyvinyl chlorides (PVC), acrylonitrile-butadine-styrene copolymers (ABS), thermoplastic polyurethanes (TPU), styrene acrylonitrile copolymers (SAN), polyphenyl oxide (PPO), acryla-styrene butyl-acrylate or acrylate styrene acrylonitrile (either of which may be abbreviated as ASA), and/or alphamethylstyrene acrylonitrile (AMSAN). In a preferred embodiment, any one or combination of ABS, PC, AMSAN, and/or PMMA may be used.Amorphous polymer6 may have any suitable size, shape, and/or configuration. For example,amorphous polymer6 may be in the form of pellets and/or flakes. In a preferred embodiment,amorphous polymer6 has a high polarity and/or decreased melt flow relative tocrystalline polymer2. The size of theamorphous polymer6 used may be dependent on these and other properties ofamorphous polymer6. For example,amorphous polymer6 may be a substantially solid chunk having dimensions (e.g., length, width, diameter, depth, and/or height) between about 0.25 inches and 0.0165 inches or may have a substantially spherical shape having an average diameter of about 0.0165 inches.
• In its solid form, polymers generally are capable of forming different structures depending on the structure of the polymer chain as well as the processing conditions. Inamorphous polymers6, the polymer chain is substantially random and unordered in structure, while incrystalline polymers2, the structure of the polymer backbone is a substantially regular, ordered structure such that the polymer can be tightly packed, although in general mostcrystalline polymer2 are only semicrystalline. This is because the exact make up and details of the polymer backbone will determine whether the polymer is capable of crystallizing. For example, PVC, depending on the characteristics of its backbone, may be either crystalline (isotactic or syndiotactic structures) or amorphous (atactic structure). Accordingly, due to these differences in polymer structures,amorphous polymers6 generally cannot fit into the semicrystalline structures of crystalline polymers2 (e.g., like incompatible puzzle pieces), andamorphous polymers6 may also exhibit polarities that prevent it from being integrated into the semicrystalline structures of crystalline polymers2 (e.g., like oil and water). Thus,amorphous polymer6 has a different solubility parameter thencrystalline polymer2. The polarities ofamorphous polymer6 may also allow it to retain polar pigments (e.g., which may be background color9) that may not bind as well tocrystalline polymer2 which is either devoid and/or has a lower polarity thanamorphous polymer6.
• Composite1 may include a plurality ofwood fibers3.Wood fibers3 may be from any type of suitable wood, for example, one or more hardwoods and/or softwoods.Wood fibers3 may be of any suitable shape and/or size, and may be configured to be suitably blended withcrystalline polymer2 such that a mixture orblend4 ofwood fibers3 andcrystalline polymer2 appears substantially homogenous in color and/or consistency. For example,wood fibers3 may have dimensions (e.g., length, width, depth, diameter, and/or height) ranging from about 6 inches to about 0.25 inches, all the way down to substantially spherical shapes having an average diameter of about 0.00079 inches. More typically, however,wood fibers3 may range in size from substantially spherical shapes having an average diameter of about 0.07870 inches to substantially spherical shapes having an average diameter of about 0.007 inches. In various embodiments, thewood fibers3 may be mixed with and/or be replaced with any suitable organic or inorganic filler material, including one or more of grass, wheat hulls, corn stocks, corn ears, nuts, nut shells, peanuts, peanut shells, walnut, walnut shells, sand, clay, dirt, and concrete.
• Second polymer6 may resist blending with first polymer2 (e.g.,second polymer6 may not be soluble infirst polymer2 and vice versa). For example, ifsecond polymer6 is an amorphous polymer andfirst polymer2 is a crystalline polymer, even when both polymers are in a melted state, the two polymers may resist blending with each other. Thus, whilesecond polymer6 may be somewhat dispersed throughoutcrystalline polymer2,second polymer6 may not be evenly distributed or blended throughout crystalline polymer2 (e.g.,amorphous polymer6 may migrate to the outer surface5). Accordingly,second polymer6 may form “clumps” and/or “pockets” incrystalline polymer2, and thus regions ofsecond polymer6 may be clearly discernible in the otherwise substantially homogenous blend ofcrystalline polymer2 andwood fibers3. For example,second polymer6 may have a different color and/or consistency than any combination ofcrystalline polymer2 andwood fibers3.
• Composite1 may have a variegated outer surface5 (i.e., a first portion ofouter surface5 may have a first color and a second portion ofouter surface5 may have a second color different from the first color). For example,outer surface5 may includestreaks16.Streaks16 may run in any direction, may have any size and/or shape, may be disposed in and/or on any portion ofcomposite1, may have any configuration, and/or may have a color different from the rest ofcomposite1. For example,streaks16 may assist composite1 in obtaining a more aesthetically pleasing wood-like appearance.Streaks16 are preferably present towardouter surface5. Any surface ofcomposite1, for example inner surfaces ofcomposite1, may havestreaks16. Variegatedouter surface5 and/orstreaks16 may provide composite1 with a more natural wood-like appearance and/or make variegatedouter surface5 look more three-dimensional.
• Due to the properties of anysecond polymer6 set forth herein, and especially with regard to its possible tendency to resist blending with crystalline polymers,second polymer6 may be responsible forstreaks16 onouter surface5 ofcomposite1. For example, when melted and mixed withcrystalline polymer2 and wood fiber blend,second polymer6 may be dispersed in the blend (e.g., mixed but not blended with the blend) such thatstreaks16 correspond to the location ofamorphous polymer6. As shown inFIG. 3A,second polymer6 is preferably disposed towardouter surface5 ofcomposite1.
• Composite1 may have anouter surface5 that includes 50% or more of second polymer6 (e.g., more than 50% of the surface area ofouter surface5 ofcomposite1 may be second polymer6). For example, as shown inFIG. 3C substantially entire portions of outer surface5 (e.g., one or more of the top, bottom, sides, and/or ends of composite1) may be composed ofsecond polymer6. Thus, in some configurations, composite1 may appear as is if it was coextruded such thatsecond polymer6 substantially surroundsfirst polymer2. In such a configuration, entire portions ofouter surface5 may appear to have substantially one color (e.g., the color ofsecond polymer6 after it has been extruded using any of the exemplary methods set forth herein), even though composite1 may include one or more components (e.g.,first polymer2,wood fibers3,blend4,second polymer6,background color9, and/or blend18) having different colors either prior to, during, or following processing.
• Second polymer6 may have a melting temperature that is substantially the same as a melting temperature ofcrystalline polymer2, as shown in the following table:

  	Polymer	Melting Temperature Range (° C.)
  	HDPE	125°-132°
  	LLDPE	110°-125°
  	LDPE	103°-110°
  	PP-Homo	160°-175°
  	PP-Copolymer	150°-175°
  	PS	74°-105°
  	ABS	88°-125°
  	SAN	100°-200°
  	PS-Rubber Mod.	93°-105°
  	PC	145°
  	AMSAN	121°
  	PMMA	212°

  
  Thus, for polymers listed above, non-melting mixing (e.g., mixing without blending) ofsecond polymer6 andcrystalline polymer2 may occur between about 140° C. and about 180° C., depending on the exact polymers used. In some embodiments, however, non-melting mixing (e.g., mixing without blending) ofsecond polymer6 andcrystalline polymer2 may occur at temperatures up to 212° C., for example, if PMMA is used assecond polymer6. Thus, the present invention has the advantage that even though the polymers used (e.g.,crystalline polymer2 and second polymer6) may have substantially the same melting temperature, the two polymers will still resist blending. In various embodiments, however, any of the polymers set forth herein may be worked at a temperature where it is still pliable in an extruder (e.g., able to be shaped using a die into a composite), yet may not have completely melted.
• Composite1 may include athird polymer7. For example,third polymer7 may be an amorphous polymer or any other second polymer set forth herein, for example, a polycarbonate and/or a polymer having a shear viscosity higher thanfirst polymer2 and/orcrystalline polymer2.Third polymer7 may be the same polymer as second polymer6 (e.g., amorphous polymer), or may be a different polymer (e.g., amorphous polymer).Third polymer7 may have the same color assecond polymer6, or may have a different color.Third polymer7 may behave similarly tosecond polymer6. For example,third polymer7 may formstreaks16 onouter surface5 ofcomposite1 that have a color different from the rest ofouter surface5. Thus, composite1 may have a plurality of streaks against a base background color ofcomposite1, with afirst set16A ofstreaks16 having a first color andsecond set16B ofstreaks16 having a second color different from the first color. One of ordinary skill in the art would realize that composite1 may include any suitable number of wood fiber types and crystalline polymers and/or amorphous or other semi-crystalline polymers and/or other suitable polymers and resins. In the example where amorphous polymers cover substantially entire portions of composite1 (e.g., as set forth inFIG. 3C),composite1 may still evince more than color, for example, one color may correspond to the presence ofamorphous polymer6 on some portions ofouter surface5 while another color may correspond to the presence ofamorphous polymer7 on other portions ofouter surface5.
• As shown inFIG. 3B, composite1 may include acore8.Core8 may have any suitable size, shape, configuration, and/or composition.Core8 may be configured to impart strength or any other suitable property tocomposite1.Core8 may itself be a wood-plastic composite. The mixture ofcrystalline polymer2,amorphous polymer6, and/orwood fibers3 may be disposed aroundcore8 and/or integrated (e.g., fused) withcore8.
• Composite1 may include abackground color9 and/or pigment.Background color9 may be configured to color one or more offirst polymer2,second polymer6,third polymer7, and/orwood fibers3. For example,backgound color9 may be processed withfirst polymer2 and/orwood fiber3 such thatbackground color9 permeatesfirst polymer2 and/orwood fiber3 and forms blend4 (e.g.,background color9 may permeate associate/engage with portions of the polymer chain of crystalline polymer2). However,blend4 may then be processed withsecond polymer6 in a suitable manner such thatbackground color9 does not substantially permeatesecond polymer6. For example, the processing ofblend4 andsecond polymer6 may occur at a lower temperature than the processing ofbackground color9,crystalline polymer2, and/orwood fiber3. In another example, the aforementioned structures of the respective polymer chains offirst polymer2 andsecond polymer6 may be substantially incompatible and/or resistant to blending (e.g., at any temperature). Accordingly,background color9 may substantially remain attached to/withinfirst polymer2 and/orblend4 and not appreciably permeatesecond polymer6.
• In various embodiments,background color9 may be added tosecond polymer6 in addition to and/or instead offirst polymer2, and any of the aforementioned characteristics may be applicable to second polymer6 (e.g., becausesecond polymer6 andfirst polymer2 are configured to resist blending,background color9 will substantially remain associated withsecond polymer6 and not first polymer2). Addingbackground color9 tosecond polymer6 and then mixing second polymer6 (which already has been mixed with background color9) with either a colored oruncolored blend4 is the preferred embodiment.Background color9 may have a polarity that increases the likelihood thatbackground color9 will remain associated with second polymer6 (e.g.,background color9 andamorphous polymer6 may have polarities that may cause them to be attracted to each other like magnets with opposing polarities) and not become associated with first polymer2 (e.g.,background color9 andfirst polymer2 may have polarities that may cause them to repel each other like magnets with substantially the same polarities).
• In another embodiment, composite1 may include another material, compound, and/or additive intermixed with at least one offirst polymer2 andsecond polymer6, for example, in substantially the same way asbackground color9 is intermixed with at least one offirst polymer2 andsecond polymer6 as set forth herein, and especially in the previous paragraph. For example, the another material may include a compound that, either on its own or when mixed with at least one offirst polymer2 andsecond polymer6, causes at least portions of composite1 (and preferablyouter surface5 of composite1) to be resistant to molding and/or mildewing (e.g., keeps the level of microorganisms, mildew, and/or mold in and/or on a composite1 lower than about 0.1 parts per million). An example of such a material may include a dichloro-octyl-isothiazolone (DCOIT) biostabilizer (e.g., biocide), such as certain grades of VINYZENE™ manufactured by ROHM AND HAAS™ (or other isothiazolones), however, any other suitable material (e.g., biostabiliter or biocide) that prevents and/or reduces molding and/or mildewing either alone or when mixed with at least one offirst polymer2 andsecond polymer6 is also acceptable. Examples of acceptable methods for determining whether a particular material (e.g., biostabilizer, biocide) suitably prevents and/or reduces mold and/or mildew oncomposite1 may include American Association for Testing Materials (ASTM™) standards ASTM™ D-1413-99 SOIL-BLACK, ASTM™ D-4445-91 SAP STAIN, ASTM™ E-1428-99 PINK STAIN, ASTM™ G-21-96 MIXED FUNGI, ASTM™ D-5583-00 SINGLE CULTURE, and/or MILITARY STANDARD 810-E HUMIDITY CHAMBER, and/or their equivalents. Indeed, in any of the embodiments set forth herein, the another material, such as the DCOIT biostabilizer, may be substituted forbackground color9 and may exhibit any of the properties ofbackground color9 relative to thefirst polymer2,second polymer6, and/orblend4 in any portion of the process.
• The DCOIT biostabilizer (examples of which may include VINYZENE™ IT 4000 Series, VINYZENE™ IT 4010 Series, and VINYZENE™ SB 27, all of which are manufactured by ROHM AND HAAS™) may be dispersed throughout thefirst polymer2, but preferably thesecond polymer6, in any concentration suitable to prevent or reduce mold or mildew growth on thecomposite1, for example, between about 800 parts per million and about 2000 parts per million and/or between about 1000 parts per million and 1200 parts per million. The DCOIT biostabilizer may have a thermal stability of about 220° C. and/or a solubility in water of about 6 parts per million.
• Another example of a suitable biostabilizer may be 10.10′-oxybisphenoxarsine (OBPA), examples of which may include VINYZENE™ BP 5-2 Series, VINYZENE™ BP 5-5 Series,VINYZENE™ SB 1, andVINYZENE™ SB 1 Series. The OBPA biostabilizer may be dispersed throughout thefirst polymer2, but preferably thesecond polymer6, in any concentration suitable to prevent or reduce mold or mildew growth on thecomposite1, for example, between about 200 parts per million and about 500 parts per million. The OBPA biostabilizer may have a thermal stability of about 300° C. and/or a solubility in water of about 6 parts per million.
• A further example of a suitable biostabilizer may be octyl-isothiazoline (OIT), examples of which may include VINYZENE™ IT 3000 Series, VINYZENE™ IT 3010 Series, VINYZENE™ IT 3025 DIDP, andVINYZENE™ SB 8. The OIT biostabilizer may be dispersed throughout thefirst polymer2, but preferably thesecond polymer6, in any concentration suitable to prevent or reduce mold or mildew growth on thecomposite1, for example, between about 800 parts per million and about 1200 parts per million. The OIT biostabilizer may have a thermal stability of about 220° C. and/or a solubility in water of about 500 parts per million.
• Yet another example of a suitable biostabilizer may be trichlorophenoxyphenol (TCPP), examples of which may include VINYZENE™ SB 30. The TCPP biostabilizer may be dispersed throughout thefirst polymer2, but preferably thesecond polymer6, in any concentration suitable to prevent or reduce mold or mildew growth on thecomposite1, for example, between about 800 parts per million and about 1200 parts per million. The TCPP biostabilizer may have a thermal stability of about 230° C. and/or a solubility in water of about 10 parts per million.
• A yet further example of a suitable biostabilizer includes biostabilizers that prevent and/or reduce the growth of any of the following exemplary fungi, bacteria, and/or actinomycetes on composite1: Alternaria, Aureobasidium, Curvularia, Aspergillus, Penicillium, Fusarium, Bigrospora, Chaetomium, Gliocladium, Helminthsporium, and/or all of the subspecies of the aforementioned fungi, bacteria, and/or actinomycetes.
• Still another example of a suitable biostabilizer (e.g., biocide) includes biostabilizers having one or more of the following features: substantially non-toxic; safe and environmentally friendly; broad spectrum; compatibility with formulation; leach and ultraviolet resistant; has sufficient thermal stability; and ease of use and handling.
• A still further example of a suitable biostabilizer may include zinc borate, which may be in the form of a crystalline powder having a solubility in water of about 2800 parts per million and a particle sizes between about 1-2 microns.
• Other examples of suitable biostabilizers (e.g., biocides) and methods for determining suitable biostabilizers for wood-plastic and other composites were disclosed in a presentation entitledMaintaining the Aesthetic Quality of WPC Decking with Isothiazolone Biocideby Peter Dylingowski, which was presented on May 20, 2003 at the 7^thInternational Conference on Wood-Fiber Plastic Composites, the entirety of which is incorporated herein by reference.
• An exemplary embodiment of the invention includes a method of manufacturing a wood-plastic composite. As shown inFIGS. 4A-4D, the method may include providing afirst polymer2, providing a plurality ofwood fibers3, providing asecond polymer6 configured to resist blending withfirst polymer2, meltingfirst polymer2, meltingsecond polymer6, mixingsecond polymer6 withfirst polymer2 andwood fibers3 to form afeed10, and forming aprofile body1.Profile body1 may include anouter surface5 deliberately evincing a first color and a second color different from the first color.Profile body1 may also include anouter surface5 being substantially composed ofsecond polymer6, with a cross-sectional profile ofprofile body1 showing that a layer ofsecond polymer6 may be substantially disposed aroundblend4 offirst polymer2 andwood fibers3.
• First polymer2 may include acrystalline polymer2.First polymer2 is preferably at least one of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polypropylene (PP), however, any crystalline polymer may be used incomposite1, such as one or more polyamides (PA), nylons, polyoxymethylenes, polybutylene terephthalates (PBT), polyethylene terephthalates (PET), and/or acetals.First polymer2 may be provided in any suitable form (e.g., pellets, flakes, sheets, etc.) to be melted, mixed withwood fibers3, and/or extruded into a dimensionally stable profile.First polymer2 may have any suitable size, shape, and/or configuration to be used in any of the apparatuses or methods disclosed in co-owned U.S. Pat. Nos. 5,851,469 and 6,527,532, co-pending and co-owned U.S. patent application Ser. No. 10/292,672 filed Nov. 12, 2002, and co-pending and co-owned U.S. patent application Ser. No. 10/668,368 filed Sep. 24, 2003, the entirety of all of which are incorporated herein by reference.First polymer2 may be processed prior to extruding thefeed10 using any suitable method. For example,first polymer2 may be chopped, purified, shredded, heated, and/or demoistured. In various embodiments,first polymer2 may be heated (e.g., by shear friction with the apparatus or by the application of external thermal energy) to completely melt, partially melt, and/or improve processability.
• First polymers2 may be selected because they have a specific color (e.g., be mixed with a certain color dye) and/or composition (e.g., allowsbackground color9 to suitable permeate its structure). However, because first polymers2 (and/or its additives such as background color9) tend to blend and form a substantially homogenous color, the specific colors and/or compositions offirst polymers2 used in the process need not be tightly controlled. Some specific dyes may affect the resulting color ofprofile body1 more than other dyes. One of ordinary skill in the art may controlfirst polymers2 input into the process in order to achieve the desired resultant color forouter surface5. Moreover, the resultant color offirst polymers2 after processing (e.g., heating and/or extrusion) may be different from the initial colors ofcrystalline polymers2.First polymer2 may have any suitable size, shape, and/or configuration, exemplary parameters for which have already been set forth herein.
• Second polymer6 may include anamorphous polymer6, a polycarbonate (PC), apolymer6 that has a higher shear viscosity thanfirst polymer2 and/orcrystalline polymer2, and/or apolymer6 configured to mix with but resist blending withfirst polymer2 and/orcrystalline polymer2. A polycarbonate is a crystalline polymer that may be used as asecond polymer6 because it may have desirable properties relative to other crystalline polymers that may be used asfirst polymers2. For example, PC may char while other crystalline polymers may burn. In another example, PC may have a sufficiently higher shear viscosity relative to other crystalline polymers. In various embodiments, using a PC assecond polymer6 in the apparatuses and methods disclosed herein will provide the same results (e.g., a composite1 with a variegatedouter surface5 and/or streaks16) as the use of anamorphous polymer6. Accordingly, PC may be used interchangeably withamorphous polymer6 in any of the embodiments set forth herein.
• Second polymer6 is preferably a styrenic polymer such as polystrene (PS), however, any amorphous polymer may be used incomposite1, such as one or more of Impact PS, polymethylmethacrylates (PMMA), polyvinyl chlorides (PVC), acrylonitrile-butadine-styrene copolymers (ABS), thermoplastic polyurethanes (TPU), styrene acrylonitrile copolymers (SAN), polyphenyl oxide (PPO), acryla-styrene butyl-acrylate or acrylate styrene acrylonitrile (either of which may be abbreviated as ASA), and/or alphamethylstyrene acrylonitrile (AMSAN). In a preferred embodiment, any one or combination of ABS, PC, AMSAN, and/or PMMA may be used.Second polymer6 may be provided in any suitable form (e.g., pellets, flakes, sheets, films, etc.)Second polymer6 may be processed prior to extruding thefeed10 using any suitable method. For example,second polymer6 may be chopped, shredded, heated, purified, and/or demoistured. In another example, background color may be added tosecond polymer6, and thensecond polymer6 may introduced into a processing apparatus, such asextruder15, substantially cold (e.g., without processing) to be mixed withblend4 and/or into the processing apparatus as close to the extruder die19 of the processing apparatus as possible to be extruded withblend4.
• Second polymer6 used may be selected based on its color and/or composition.Second polymer6 may have an initial color and/or resultant color that is different from the initial color and/or resultant color of the one or more crystalline polymers (with or without wood fibers3) thatsecond polymer6 is being mixed with. For example,crystalline polymers2, after processing (with or withoutwood fibers3 and/or background color9), may result in a substantially gray color, whilesecond polymer6, after processing, may result in a substantially black color.Second polymer6 may have any suitable size, shape, and/or configuration. For example,second polymer6 may be provided in flake or pellet form.
• First polymer2 and/orsecond polymer6 may be melted using any suitable method. For example,first polymer2 and/orsecond polymer6 may be heated using in an external heat source (e.g., a flame in a heater13) or may be heated through kinetic energy (e.g., by passing through abarrel12 with arotating screw11, or passing through extruder die19).First polymer2 and/orsecond polymer6 may be melted at any point in the composite manufacturing process prior to formingprofile body1.First polymer2 and/orsecond polymer6 may be heated separately and/or together. In a preferred embodiment,first polymer2 and/or wood-fibers3 may be heated and blended to formblend4.First polymer2 may be heated substantially throughoutfirst polymer2 and/or enough to improve processability (e.g., mixing and/or blending).
• Wood fibers3 may be from any type of suitable wood, for example, one or more hardwoods and/or softwoods.Wood fibers3 may also be mixed with and/or replaced by any organic or inorganic filler such as those set forth herein.Wood fibers3 may be of any suitable shape and/or size, and may be configured to be suitably blended withfirst polymer2 such that a mixture ofwood fibers3 andfirst polymer2 appears substantially homogenous in color.Wood fibers3 may be processed prior to formingprofile body1 using any suitable method. For example,wood fibers3 may be ground, crushed, chopped, shredded, heated, purified, and/or demoisturized.Wood fibers3 may be dried prior to being blended withfirst polymer2 to formblend4. In some cases, pieces ofwood fiber3 may be discernible inblend4, however,wood fiber3 will still typically have the same homogenous color as the rest ofblend4.
• First polymer2 may be blended in aprocessor13 withwood fibers3 such thatblend4 is substantially homogenous. For example,blend4 may have one substantially solid color and/or have a substantially uniform consistency.Blend4 may be formed using any suitable method.First polymer2 andwood fibers3 may be blended by placing them together either before, during, or afterfirst polymer2 and/orwood fibers3 are dried.First polymer2 andwood fibers3 may be blended using applied heat and/or mechanical agitation. Such blending may be accomplished by an extruder, high shear device, and/or a low shear mixer with or without the application of heat.
• Second polymer6 may be mixed withfirst polymer2 andwood fibers3 to form afeed10 in any suitable order, any suitable ratio, and using any suitable method. For example,first polymer2,second polymer6, and plurality ofwood fibers3 may be mixed as they are advanced by one ormore screws11 in abarrel12 and/or extruded throughdie19.Second polymer6 may be mixed withfirst polymer2 andwood fibers3 at any time prior to extruding the feed and in any relative order. For example,first polymer2 may be blended withwood fibers3, the blend may be heated, and thensecond polymer6 may be added to the blend. In another example,first polymer2,second polymer6, andwood fibers3 may be combined at substantially the same time and mixed simultaneously.Second polymer6 may be mixed withfirst polymer2 andwood fibers3 such that the mixture does not blend. For example, the mixture may be heated to a temperature that allows mixing but not blending.
• In another example,second polymer6 may be added to blend4 to formfeed10 just prior to extrudingfeed10 through extruder die19. Thus, heating ofsecond polymer6 may only occur just after introducingsecond polymer6 intoblend4 and/or during extrusion offeed10 through extruder die19. Accordingly,second polymer6 may experience less of a heat history than any offirst polymer2,wood fibers3, and/orblend4, which may assist in preventing blending.
• In a further example, the structures (e.g., crystalline structures, lack of crystalline structures, polymer backbones, polarity, compositions, etc.) offirst polymer2 andsecond polymer6 may assist in preventing thepolymers2,6, from substantially blending. Exemplary percentages offirst polymer2,second polymer6, andwood fibers3 are listed herein, however, generally, the percentage offirst polymer2 will exceed the percentage ofsecond polymer6.
• In various embodiments, composite1 may include between about 100% and about 20% offirst polymer2, between about 5% and about 0% ofsecond polymer6, and between about 0% and about 80% wood fiber or other filler. In a preferred embodiment, composite1 may include between about 60% and about 53% offirst polymer2, about 2% ofsecond polymer6, and between about 45% and about 38% wood fiber or other filler
• Besides having a more natural, smooth, non-monolithic, and/or three-dimensional looking surface,composites1 discussed herein may have other advantages. For example, composite1 may be less susceptible to mold and mildew and/or may be more durable.First polymer2 andsecond polymer6 do not blend incomposites1. Accordingly, the minor component (in this case, second polymer6) may migrate to theouter surface5 ofcomposite1. When the minor component migrates toouter surface5 ofcomposite1, the minor component may tend to coat at least portions of outer surface5 (e.g., top, bottom, and/or side surfaces) with a polymer rich coating that does not absorb moisture, and thus allowsouter surface5 to resist molding and/or mildewing. Moreover, additional additives, such as mold and mildew resistant compounds (e.g., DCOIT biostabilizers or other suitable anti-fungi.bacteria materials/compounds, examples of which are set forth herein, or other materials having other desirable properties for composite1), may be added tosecond polymer6 at any point before or during the manufacturing process ofcomposite1. During the addition of the additive tosecond polymer6, the additive andsecond polymer6 may be processed so as to substantially disperse the additive through the matrix ofsecond polymer6. Once again, becausesecond polymer6 may migrate toouter surface5 ofcomposite1,second polymer6 with mildew resistant additives (or other materials) may coat at least portions ofouter surface5. Some exemplary reasons whysecond polymer6 may migrate towardouter surface5 ofcomposite1 are set forth herein, and especially below.
• This type of delivery of the mold and mildew resistant materials and/or compounds, examples of which are set forth herein, (or other compounds with other desirable properties) to specific portions ofcomposite1 may have many advantages. For example, the compounds themselves may be relatively expensive and/or including too much of the compound incomposite1 may compromise some structural and/or aesthetic properties ofcomposite1. Thus, there may be a need to minimize the amount of the compound incomposite1 by delivering the compound to portions of the composite1 where the compound may be most effective. In the case of mildew and/or mold resistant compounds (examples of which are set forth herein), such compounds may be most effective on at least portions ofouter surface5 ofcomposite1. Accordingly, because the properties (e.g., crystalline structure, solubility, or other properties like or similar to those set forth herein) of first polymer2 (e.g., crystalline polymer) and second polymer6 (e.g., amorphous polymer) causessecond polymer6, when extruded, to migrate away from first polymer2 (e.g., with or without wood fibers3) and/or towardouter surface5 ofcomposite1,second polymer6 may be used as a vehicle to deliver desirable compounds on and/or towardouter surface5. In some cases, if the property of the compound is desirable along large portions ofouter surface5, thensecond polymer6 with the desirable compound may be disposed along entire portions ofouter surface5, for example, as set forth inFIG. 3C.
• Profile body1 with anouter surface5 may be formed using any suitable method. For example, the mixture including first polymer2 (e.g., crystalline polymer), second polymer6 (e.g., amorphous polymer), andwood fibers3 may be extruded through a die19 to formprofile body1.Feed10 may be extruded using either a single screw extruder or a double screw extruder to formprofile body1.Feed10 may also be formed intoprofile body1 using any suitable method.
• Outer surface5 ofprofile body1 may be variegated.Streaks16 may be formed onouter surface5 ofprofile body1. For example, iffirst polymer2 andsecond polymer6 are mixed, the chemical properties of the two polymers and/or the processing conditions (e.g., temperature, extrusion rate, mixing rate that the two polymers are subjected to) may prevent them from blending with each other and forming a homogenous color. Accordingly, “clumps” or “pockets” ofsecond polymer6 may be dispersed throughfirst polymer2 and vice versa. As the mixture ofsecond polymer6 and first polymer2 (with or without wood fibers3) is extruded through thedie19,second polymer6 may tend to go towardsouter surface5 ofprofile body1, for example, due the pressures exerted onfeed10 during extrusion. In another example, due to the molecular structure of bothfirst polymer2 andsecond polymer6, the polymer chain ofsecond polymer6 cannot interlock easily with the polymer chain and/or matrix offirst polymer2. Accordingly,second polymer6 may tend to separate from the polymer matrix offirst polymer2 and go toouter surface5 so as to form its own solid polymer matrix ofsecond polymer6. Assecond polymer6 reachessurface5, becausesecond polymer6 may have a different initial color and/or different resultant color as the rest of profile body1 (i.e.,blend4 offirst polymer2 and wood fibers3),streaks16 ofsecond polymer6 may be readily discernible onouter surface5.Streaks16 may be generally perpendicular to a cross-section ofdie19 through whichprofile body1 is extruded. However,streaks16 may be in any direction, and have any other shape and/or configuration, for example, similar to those set forth inFIGS. 2A-2C.Streaks16 may form any desired or suitable pattern, for example, a natural-wood-like pattern.
• In another example, entire portions ofouter surface5 may be composed ofsecond polymer6, for example, as shown inFIG. 3C. In such an example, the processing may have been such thatsecond polymer6 forms “clumps” or “pockets” (e.g., as set forth in the previous paragraph) around substantially all ofblend4 so as to form a substantially solid matrix around blend4 (e.g., with or without wood fibers3). Any suitable proportions ofsecond polymer6,first polymer2, wood-fibers3,blend4, blend18,background color9, and another other material or compound set forth herein are contemplated as being discernible onouter surface5.
• The method may also include providing anotherpolymer7, melting anotherpolymer7, and mixing anotherpolymer7 withsecond polymer6,first polymer2, and/orwood fibers3. With the addition ofadditional polymer7, the step of extruding may include formingprofile body1 such thatouter surface5 deliberately evinces a third color different from the first color and the second color due toadditional polymer7.
• Anotherpolymer7 may be selected because its initial color and/or resultant color may be different from an initial color and/or resultant color of one or more offirst polymer2 and/orwood fibers3. Anotherpolymer7 may processed and/or behave similarly to othersecond polymers6, thus,streaks16B of anotherpolymer7 may be formed onouter surface5 ofprofile body1.Streaks16B from anotherpolymer7 may be of a color different from either the base color ofprofile body1 and/or the color ofstreaks16A fromsecond polymer6.
• As shown inFIG. 4B, the method may also include providing acore8 and formingprofile body1 around at least a portion ofcore8.Core8 may be a wood-plastic composite or any other suitable composite.Core8 may have a cross-sectional area smaller than a cross-sectional area ofdie19.Core8 may be fed byextruder15 throughdie19 such thatcore8 advances through substantially the center ofdie19 without contacting any portion ofdie19 itself.Extruder15 and/or die19 may then deposit anouter surface5 oncore8 that has more than one color (e.g., variegated and/or streaked) using one or more of the methods set forth herein. Thevariegated surface5 may be bonded tocore8 using any suitable method, for example, whenvariegated surface5 is co-extruded ontocore8, a portion ofcore8 may melt and intermix withvariegated surface5 such thatcore8 and thevariegated surface5 are substantially fused. Accordingly, the resultant product may be a building material with acore8 having a wood-plastic composite having a deliberately variegatedouter surface5 formed around it. Such a resultant product may be desirable, for example, to impart strength to the component (e.g., by providing a core component having a high strength such as aluminum or steel).
• The method also may include the use of abackground color9. As shown inFIG. 4B,background color9 may be added tofirst polymer2 and/or wood fiber3 (e.g., blend4) to impart a color to blend4 different from an initial color ofblend4,first polymer2, and/orwood fiber3.Background color9,first polymer2,wood fibers3, and/orblend4 may be processed byprocessor13 using any suitable apparatus and/or method to formresultant blend14.Resultant blend14 may then be transferred toextruder15 and processed withsecond polymer6 to formprofile body1 withstreaks16 or other variations ofouter surface5 as set forth herein.Background color9 may be added to any step of the process and/or any component or subcomponent of the process at any time prior to extrusion throughdie19.
• In a preferred embodiment, as shown inFIG. 4C,background color9 may be added tosecond polymer6 to impart a color tosecond polymer6 different from an initial color ofsecond polymer6.Background color9 and/orsecond polymer6 may be processed byprocessor17 using any suitable apparatus and/or method to formresultant blend18 ofsecond polymer6 andbackground color9.Resultant blend18 may then be transferred toextruder15 and processed withfirst polymer2,wood fibers3, and/orblend4 to formprofile body1 withstreaks16 or other variations ofouter surface5 as set forth herein. Once again,background color9 may be added to any step of the process and/or any component or subcomponent of the process at any time prior to extrusion throughdie19.
• In another preferred embodiment, as shown inFIGS. 4D and 4E,first polymer2 and plurality ofwood fibers3 may be processed (e.g., dried and/or pre-melted) using any suitable apparatus and/or method to formblend4.Background color9 may be added tofirst polymer2 and/or wood fiber3 (e.g., blend4) to impart a color to blend4 different from an initial color ofblend4,first polymer2, and/orwood fiber3.Background color9,first polymer2,wood fibers3, and/orblend4 may be processed byprocessor13 using any suitable apparatus and/or method to formresultant blend14.Background color9,first polymer2, and/orwood fiber3 may mixed together and/or processed at substantially the same time to formresultant blend14 without first formingblend4, orbackground color9 may be added to blend4 after the processing offirst polymer2 and/orwood fiber3 has already begun and/or has been completed.Resultant blend14 may then be transferred toextruder15.
• Second polymer6 may then be added toresultant blend14 and/or feed10 that is now disposed inextruder15.Second polymer6 may be added in any suitable form, for example, unmelted pellets. The pellets may have any suitable shape, size, and/or configuration. For example, the pellets preferably range in size from 15 pellets per gram to 30 pellets per gram (e.g., 25 pellets per gram) and even up to 40 pellets per gram.
• Second polymer6 may be added to any portion ofresultant blend14 and/or feed10 disposed in any portion ofextruder15,barrel12, and/orscrew11. For example,second polymer6 may be added through avent port20 disposed on a side ofextruder15 and/orbarrel12.Vent port20 may be disposed at approximately a halfway position along a length ofextruder15,barrel12, and/or screw11, which may be a low-pressure region relative to the rest ofextruder15.Vent port20 may be disposed downstream from a blister11bonscrew11, which may cause region ofextruder15 adjacent to ventport20 to be a low pressure region.Vent port20 may be connected to aside feeder21, for example, as shown inFIGS. 4D and 4E.
• Side feeder21 may include afeed screw22 driven by a variablespeed motor drive23. Abarrel24 may surroundfeed screw22near vent port20 and may be connected to an outer surface ofextruder15.Feed screw22 may be disposed such thatfeed screw22 placessecond polymer6 intoextruder15 without forcingsecond polymer6 intoscrew11.Feed screw22 and screw11 do not contact each other.
• Barrel24 (e.g., also called an extruder vent stack) may include a vacuum section26 configured to remove impurities fromsecond polymer6 disposed inbarrel24, for example, turpentine and/or organic materials. This may prevent foaming later in the process. A distal end27 ofbarrel24 may include adoor28.Door28 may be configured to allowsecond polymer6 to be placed therethrough into an interior ofbarrel24 such thatsecond polymer6 may be fed intoextruder15.
• Distal tobarrel24 may bebasket31.Basket31 may be configured to receivesecond polymer6 in any suitable form, for example, unmelted pellets. A hose29 may connect an outlet ofbasket31 to door28 so as to allowsecond polymer6 to be advanced frombasket31 todoor28. Hose clamp30 may connect hose29 to each ofdoor28 and the outlet ofbasket31. Hose clamp30 may form a substantially airtight seal betweendoor28, hose29,basket31, and/orbarrel24.Basket31 may include a lid32 disposed on a gasket disposed around an upper end ofbasket31. Lid32 may be configured to maintain a substantially airtight seal withbasket31, for example, to maintain a desired air pressure inbasket31. A desired air pressure may be an air pressure above that inbarrel24 so as to assist in movingsecond polymer6 frombasket31, through hose29, and intobarrel24. Lid32 may include avent33, for example a ¼ turn ball valve, to assist in maintaining a desired air pressure inbasket31.Barrel24 may extend distal todoor28, underbasket31, and/or tomotor23.Barrel24 in this region may have a smaller cross-sectional area (e.g., diameter) relative to the region ofbarrel24 adjacent to ventport20. Alip seal34 may provide a substantially airtight seal betweenfeed screw22 andbarrel24. Any cracks or gaps between any portions of side feeder21 (e.g., betweenbasket31,feed screw22,lip seal34,barrel24,door28, hose29, and/or hose clamp30) may be sealed with a sealant, for example, silicon caulk.
• Side feeder21 may be disposed on an adjustable table35, for example, to adjust the height ofside feeder21 relative toextruder15. This adjustablility may be desirable, for example, to locateside feeder21 at an ideal height such thatsecond polymer6 flows intobarrel12 ofextruder15 at a desired rate and/or at a desired location (e.g., intobarrel12 without exerting excessive force onscrew11 which may cause excessive mixing ofsecond polymer6 withresultant blend14 and/or feed10). A longitudinal axis ofside feeder21,barrel24, and/or feedscrew22 may be substantially parallel to the ground and/or substantially perpendicular to a longitudinal axis ofscrew11,extruder15, and/orbarrel12.
• Oncesecond polymer6 has been introduced intoresultant blend14 and/or feed10,second polymer6 may mix, but not blend, withresultant blend14 and/or feed10 and may be extruded intocomposite1 via extruder die19.Composite1 may have a variegatedouter surface5 and/orstreaks16.
• One of ordinary skill in the art will recognize that some aspects of the invention may be modified so as to form different embodiments of the invention. For example, there may be a plurality of first polymers, a plurality of types of wood fibers, and/or a plurality of second polymers used.
• Further, various resins other than or in addition to crystalline and/or amorphous polymers may be used for any polymer set forth herein, for example,first polymer2,second polymer6, and/orthird polymer7. For example, crystalline, amorphous, and/or semi-crystalline or any other suitable polymer or resin, whether natural or synthetic may be used.
• Further, the same polymer or resin may be used as both the first and second polymer, provided that one or the other is modified in some way (i.e., an additive or different levels of an additive) so that they do not blend as used in the invention. An additive may be any suitable material, for example, an organic material and/or a chemical (e.g., any chemicals, such as biocides, set forth herein).
• One of ordinary skill of art will further recognize that some of the aspects of set forth herein may be combined with other aspects set forth herein to form different embodiments of the invention. For example, composite1 with streaks having multiple colors may also include a core.
• One of ordinary skill in the art will also recognize that some of the aspects set forth herein may be removed to form different embodiments of the invention. For example,first polymer2 and wood fibers need not be blended prior to mixing them withsecond polymer6.
• Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims (24)

1. A composite, comprising:

a first polymer;

a plurality of wood fibers dispersed in the first polymer;

an outer surface; and

a second polymer adapted to not blend substantially with the first polymer;

wherein the first polymer and the second polymer form a pattern on the outer surface of the composite.

2. The composite ofclaim 1, wherein the first polymer is at least one of polypropylene and polyethylene.

3. The composite ofclaim 1, wherein the second polymer is at least one of a polymethylmethacrylate, an alphamethylstyrene acrylonitrile, and a polycarbonate.

4. The composite ofclaim 1, wherein the outer surface includes streaks of the second polymer.

5. The composite ofclaim 1, wherein the first polymer has a melting temperature that is substantially the same as a melting temperature of the second polymer.

6. The composite ofclaim 1, wherein the outer surface is variegated.

7. The composite ofclaim 1, wherein a first portion of the outer surface has a first color and a second portion of the outer surface has a second color.

8. The composite ofclaim 1, further comprising a third polymer configured to resist blending with the first polymer;

wherein the composite is manufactured such that the third polymer is deliberately visible on the outer surface,

wherein the third polymer has a third color different from the first polymer and the second polymer.

9. The composite ofclaim 1, wherein the composite is at least one of a building material, a decking material, a railing component, and a decking board.

10. The composite ofclaim 1, further comprising a colorant blended with one of the first polymer and the second polymer.

11. A method of manufacturing a wood-plastic composite, comprising:

providing a first polymer;

providing a plurality of wood fibers;

providing a second polymer not substantially soluble in the first polymer;

melting the first polymer;

blending the first polymer and the plurality of wood fibers to form a blend;

adding the second polymer in an unmelted state to the blend to form a feed; and

forming a profile body from the feed, the profile body further comprising a pattern formed by the first polymer and the second polymer.

12. The method ofclaim 11, further comprising forming streaks of the second polymer on the outer surface.

13. The method ofclaim 11, further comprising forming streaks of the first polymer on the outer surface.

14. The method ofclaim 11, further comprising shifting the second polymer towards the outer surface.

15. The method ofclaim 11, further comprising variegating the outer surface.

16. The method ofclaim 11, further comprising providing at least one of a single screw extruder and a double screw extruder,

wherein the step of extruding includes extruding the feed via the at least one of the single-screw extruder and the double screw extruder.

17. The method ofclaim 11, wherein the step of mixing includes forming a first color from the second polymer and forming the second color from a blend of the first polymer and the plurality of wood fibers.

18. The method ofclaim 11, further comprising providing a third polymer not substantially soluble in the first polymer;

adding the third polymer in an unmelted state to the blend to form the feed,

wherein the step of extruding includes forming the profile body such that the outer surface deliberately evinces a third color different from the first polymer and the second polymer.

19. The method ofclaim 11, further comprising providing a core,

wherein the step of forming the profile body includes forming the profile body around at least a portion of the core.

20. The method ofclaim 11, further comprising providing a colorant; and

blending the colorant with one of the first polymer and the second polymer.

21. The composite ofclaim 1, wherein the first polymer has a first color and the second polymer has a second color.

22. The composite ofclaim 1, wherein the second polymer is not substantially soluble in the first polymer.

23. The method ofclaim 11, wherein the first polymer has a first color and the second polymer has a second color.

24. The method ofclaim 11, wherein the second polymer is not substantially soluble in the first polymer.

Images