US20050271889A1

US20050271889A1 - Variegated composites and related methods of manufacture

Info

Publication number: US20050271889A1
Application number: US11/094,795
Authority: US
Inventors: Blair Dolinar
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-06-08
Filing date: 2005-03-31
Publication date: 2005-12-08
Also published as: US20050271872A1; US7410687B2; US20070087181A1; MXPA06014301A; US20070087180A1; US20060068215A2

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 of FIG. 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 of FIG. 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 of FIG. 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 of FIG. 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, and 3A-3C, composite 1 may include a first polymer 2, a plurality of wood fibers 3 blended with first polymer 2 to form a blend 4, an outer surface 5, and a second polymer 6 configured to resist blending with first polymer 2 (e.g., second polymer 6 is not substantially soluble in first polymer 2). Second polymer 6 may be visible on outer surface 5. Blend 4 of first polymer 2 and wood fibers 3 may have a first color and second polymer 6 may have a second color different from the first color.
Composite 1 may be used as a decking component or any other suitable building material. For example, as shown in FIG. 1, composite 1 may be used as a decking board, railing, railing post, and/or decking beam. In another example, composite 1 may be used to construct any portions of homes, walkways, shelters, and/or any other desirable structure.
Composite 1 may include a first polymer 2 which may be a crystalline polymer 2. Crystalline polymer 2 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 polymer 2 may have any suitable size, shape, and/or configuration to be melted, mixed with wood fibers 3, and/or extruded into a dimensionally stable profile. Crystalline polymer 2 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 polymer 2 may be in the form of a pellet, a flake, a film, and/or a scrap form. In another example, crystalline polymer 2 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 polymer 2 is film scrap having dimensions (e.g., length, width, height, depth, and/or diameter) between about 0.0787 inches and 0.25 inches.
Composite 1 may include a second polymer 6 which may be an amorphous polymer 6, a polycarbonate (PC), a polymer 6 that has a higher shear viscosity than first polymer 2 and/or crystalline polymer 2, and/or a polymer 6 configured to mix with but resist blending with first polymer 2 and/or crystalline polymer 2. A polycarbonate is a crystalline polymer that may be used as a second polymer 6 because it may have desirable properties relative to other crystalline polymers that may be used as first polymers 2. 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 as second polymer 6 in the apparatuses and methods disclosed herein will provide the same results (e.g., a composite 1 with a variegated outer surface 5 and/or streaks 16) as the use of an amorphous polymer 6. Accordingly, PC may be used interchangeably with amorphous polymer 6 in any of the embodiments set forth herein.
Amorphous polymer 6 is preferably a styrenic polymer such as polystrene (PS). However, any amorphous polymer may be used in composite 1, 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 polymer 6 may have any suitable size, shape, and/or configuration. For example, amorphous polymer 6 may be in the form of pellets and/or flakes. In a preferred embodiment, amorphous polymer 6 has a high polarity and/or decreased melt flow relative to crystalline polymer 2. The size of the amorphous polymer 6 used may be dependent on these and other properties of amorphous polymer 6. For example, amorphous polymer 6 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. In amorphous polymers 6, the polymer chain is substantially random and unordered in structure, while in crystalline polymers 2, the structure of the polymer backbone is a substantially regular, ordered structure such that the polymer can be tightly packed, although in general most crystalline polymer 2 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 polymers 6 generally cannot fit into the semicrystalline structures of crystalline polymers 2 (e.g., like incompatible puzzle pieces), and amorphous polymers 6 may also exhibit polarities that prevent it from being integrated into the semicrystalline structures of crystalline polymers 2 (e.g., like oil and water). Thus, amorphous polymer 6 has a different solubility parameter then crystalline polymer 2. The polarities of amorphous polymer 6 may also allow it to retain polar pigments (e.g., which may be background color 9) that may not bind as well to crystalline polymer 2 which is either devoid and/or has a lower polarity than amorphous polymer 6.
Composite 1 may include a plurality of wood fibers 3. Wood fibers 3 may be from any type of suitable wood, for example, one or more hardwoods and/or softwoods. Wood fibers 3 may be of any suitable shape and/or size, and may be configured to be suitably blended with crystalline polymer 2 such that a mixture or blend 4 of wood fibers 3 and crystalline polymer 2 appears substantially homogenous in color and/or consistency. For example, wood fibers 3 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 fibers 3 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, the wood fibers 3 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 polymer 6 may resist blending with first polymer 2 (e.g., second polymer 6 may not be soluble in first polymer 2 and vice versa). For example, if second polymer 6 is an amorphous polymer and first polymer 2 is a crystalline polymer, even when both polymers are in a melted state, the two polymers may resist blending with each other. Thus, while second polymer 6 may be somewhat dispersed throughout crystalline polymer 2, second polymer 6 may not be evenly distributed or blended throughout crystalline polymer 2 (e.g., amorphous polymer 6 may migrate to the outer surface 5). Accordingly, second polymer 6 may form “clumps” and/or “pockets” in crystalline polymer 2, and thus regions of second polymer 6 may be clearly discernible in the otherwise substantially homogenous blend of crystalline polymer 2 and wood fibers 3. For example, second polymer 6 may have a different color and/or consistency than any combination of crystalline polymer 2 and wood fibers 3.
Composite 1 may have a variegated outer surface 5 (i.e., a first portion of outer surface 5 may have a first color and a second portion of outer surface 5 may have a second color different from the first color). For example, outer surface 5 may include streaks 16. Streaks 16 may run in any direction, may have any size and/or shape, may be disposed in and/or on any portion of composite 1, may have any configuration, and/or may have a color different from the rest of composite 1. For example, streaks 16 may assist composite 1 in obtaining a more aesthetically pleasing wood-like appearance. Streaks 16 are preferably present toward outer surface 5. Any surface of composite 1, for example inner surfaces of composite 1, may have streaks 16. Variegated outer surface 5 and/or streaks 16 may provide composite 1 with a more natural wood-like appearance and/or make variegated outer surface 5 look more three-dimensional.
Due to the properties of any second polymer 6 set forth herein, and especially with regard to its possible tendency to resist blending with crystalline polymers, second polymer 6 may be responsible for streaks 16 on outer surface 5 of composite 1. For example, when melted and mixed with crystalline polymer 2 and wood fiber blend, second polymer 6 may be dispersed in the blend (e.g., mixed but not blended with the blend) such that streaks 16 correspond to the location of amorphous polymer 6. As shown in FIG. 3A, second polymer 6 is preferably disposed toward outer surface 5 of composite 1.
Composite 1 may have an outer surface 5 that includes 50% or more of second polymer 6 (e.g., more than 50% of the surface area of outer surface 5 of composite 1 may be second polymer 6). For example, as shown in FIG. 3C substantially entire portions of outer surface 5 (e.g., one or more of the top, bottom, sides, and/or ends of composite 1) may be composed of second polymer 6. Thus, in some configurations, composite 1 may appear as is if it was coextruded such that second polymer 6 substantially surrounds first polymer 2. In such a configuration, entire portions of outer surface 5 may appear to have substantially one color (e.g., the color of second polymer 6 after it has been extruded using any of the exemplary methods set forth herein), even though composite 1 may include one or more components (e.g., first polymer 2, wood fibers 3, blend 4, second polymer 6, background color 9, and/or blend 18) having different colors either prior to, during, or following processing.

Second polymer

6 may have a melting temperature that is substantially the same as a melting temperature of crystalline polymer 2, 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) of second polymer 6 and crystalline polymer 2 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) of second polymer 6 and crystalline polymer 2 may occur at temperatures up to 212° C., for example, if PMMA is used as second polymer 6. Thus, the present invention has the advantage that even though the polymers used (e.g., crystalline polymer 2 and second polymer 6) 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.

Composite 1 may include a third polymer 7. For example, third polymer 7 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 than first polymer 2 and/or crystalline polymer 2. Third polymer 7 may be the same polymer as second polymer 6 (e.g., amorphous polymer), or may be a different polymer (e.g., amorphous polymer). Third polymer 7 may have the same color as second polymer 6, or may have a different color. Third polymer 7 may behave similarly to second polymer 6. For example, third polymer 7 may form streaks 16 on outer surface 5 of composite 1 that have a color different from the rest of outer surface 5. Thus, composite 1 may have a plurality of streaks against a base background color of composite 1, with a first set 16A of streaks 16 having a first color and second set 16B of streaks 16 having a second color different from the first color. One of ordinary skill in the art would realize that composite 1 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 composite 1 (e.g., as set forth in FIG. 3C), composite 1 may still evince more than color, for example, one color may correspond to the presence of amorphous polymer 6 on some portions of outer surface 5 while another color may correspond to the presence of amorphous polymer 7 on other portions of outer surface 5.
As shown in FIG. 3B, composite 1 may include a core 8. Core 8 may have any suitable size, shape, configuration, and/or composition. Core 8 may be configured to impart strength or any other suitable property to composite 1. Core 8 may itself be a wood-plastic composite. The mixture of crystalline polymer 2, amorphous polymer 6, and/or wood fibers 3 may be disposed around core 8 and/or integrated (e.g., fused) with core 8.
Composite 1 may include a background color 9 and/or pigment. Background color 9 may be configured to color one or more of first polymer 2, second polymer 6, third polymer 7, and/or wood fibers 3. For example, backgound color 9 may be processed with first polymer 2 and/or wood fiber 3 such that background color 9 permeates first polymer 2 and/or wood fiber 3 and forms blend 4 (e.g., background color 9 may permeate associate/engage with portions of the polymer chain of crystalline polymer 2). However, blend 4 may then be processed with second polymer 6 in a suitable manner such that background color 9 does not substantially permeate second polymer 6. For example, the processing of blend 4 and second polymer 6 may occur at a lower temperature than the processing of background color 9, crystalline polymer 2, and/or wood fiber 3. In another example, the aforementioned structures of the respective polymer chains of first polymer 2 and second polymer 6 may be substantially incompatible and/or resistant to blending (e.g., at any temperature). Accordingly, background color 9 may substantially remain attached to/within first polymer 2 and/or blend 4 and not appreciably permeate second polymer 6.
In various embodiments, background color 9 may be added to second polymer 6 in addition to and/or instead of first polymer 2, and any of the aforementioned characteristics may be applicable to second polymer 6 (e.g., because second polymer 6 and first polymer 2 are configured to resist blending, background color 9 will substantially remain associated with second polymer 6 and not first polymer 2). Adding background color 9 to second polymer 6 and then mixing second polymer 6 (which already has been mixed with background color 9) with either a colored or uncolored blend 4 is the preferred embodiment. Background color 9 may have a polarity that increases the likelihood that background color 9 will remain associated with second polymer 6 (e.g., background color 9 and amorphous polymer 6 may have polarities that may cause them to be attracted to each other like magnets with opposing polarities) and not become associated with first polymer 2 (e.g., background color 9 and first polymer 2 may have polarities that may cause them to repel each other like magnets with substantially the same polarities).
In another embodiment, composite 1 may include another material, compound, and/or additive intermixed with at least one of first polymer 2 and second polymer 6, for example, in substantially the same way as background color 9 is intermixed with at least one of first polymer 2 and second polymer 6 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 of first polymer 2 and second polymer 6, causes at least portions of composite 1 (and preferably outer surface 5 of composite 1) to be resistant to molding and/or mildewing (e.g., keeps the level of microorganisms, mildew, and/or mold in and/or on a composite 1 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 of first polymer 2 and second polymer 6 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 on composite 1 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 for background color 9 and may exhibit any of the properties of background color 9 relative to the first polymer 2, second polymer 6, and/or blend 4 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 the first polymer 2, but preferably the second polymer 6, in any concentration suitable to prevent or reduce mold or mildew growth on the composite 1, 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, and VINYZENE™ SB 1 Series. The OBPA biostabilizer may be dispersed throughout the first polymer 2, but preferably the second polymer 6, in any concentration suitable to prevent or reduce mold or mildew growth on the composite 1, 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, and VINYZENE™ SB 8. The OIT biostabilizer may be dispersed throughout the first polymer 2, but preferably the second polymer 6, in any concentration suitable to prevent or reduce mold or mildew growth on the composite 1, 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 the first polymer 2, but preferably the second polymer 6, in any concentration suitable to prevent or reduce mold or mildew growth on the composite 1, 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 composite 1: 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 entitled Maintaining the Aesthetic Quality of WPC Decking with Isothiazolone Biocide by 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 in FIGS. 4A-4D, the method may include providing a first polymer 2, providing a plurality of wood fibers 3, providing a second polymer 6 configured to resist blending with first polymer 2, melting first polymer 2, melting second polymer 6, mixing second polymer 6 with first polymer 2 and wood fibers 3 to form a feed 10, and forming a profile body 1. Profile body 1 may include an outer surface 5 deliberately evincing a first color and a second color different from the first color. Profile body 1 may also include an outer surface 5 being substantially composed of second polymer 6, with a cross-sectional profile of profile body 1 showing that a layer of second polymer 6 may be substantially disposed around blend 4 of first polymer 2 and wood fibers 3.
First polymer 2 may include a crystalline polymer 2. First polymer 2 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 in composite 1, such as one or more polyamides (PA), nylons, polyoxymethylenes, polybutylene terephthalates (PBT), polyethylene terephthalates (PET), and/or acetals. First polymer 2 may be provided in any suitable form (e.g., pellets, flakes, sheets, etc.) to be melted, mixed with wood fibers 3, and/or extruded into a dimensionally stable profile. First polymer 2 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 polymer 2 may be processed prior to extruding the feed 10 using any suitable method. For example, first polymer 2 may be chopped, purified, shredded, heated, and/or demoistured. In various embodiments, first polymer 2 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 polymers 2 may be selected because they have a specific color (e.g., be mixed with a certain color dye) and/or composition (e.g., allows background color 9 to suitable permeate its structure). However, because first polymers 2 (and/or its additives such as background color 9) tend to blend and form a substantially homogenous color, the specific colors and/or compositions of first polymers 2 used in the process need not be tightly controlled. Some specific dyes may affect the resulting color of profile body 1 more than other dyes. One of ordinary skill in the art may control first polymers 2 input into the process in order to achieve the desired resultant color for outer surface 5. Moreover, the resultant color of first polymers 2 after processing (e.g., heating and/or extrusion) may be different from the initial colors of crystalline polymers 2. First polymer 2 may have any suitable size, shape, and/or configuration, exemplary parameters for which have already been set forth herein.
Second polymer 6 may include an amorphous polymer 6, a polycarbonate (PC), a polymer 6 that has a higher shear viscosity than first polymer 2 and/or crystalline polymer 2, and/or a polymer 6 configured to mix with but resist blending with first polymer 2 and/or crystalline polymer 2. A polycarbonate is a crystalline polymer that may be used as a second polymer 6 because it may have desirable properties relative to other crystalline polymers that may be used as first polymers 2. 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 as second polymer 6 in the apparatuses and methods disclosed herein will provide the same results (e.g., a composite 1 with a variegated outer surface 5 and/or streaks 16) as the use of an amorphous polymer 6. Accordingly, PC may be used interchangeably with amorphous polymer 6 in any of the embodiments set forth herein.
Second polymer 6 is preferably a styrenic polymer such as polystrene (PS), however, any amorphous polymer may be used in composite 1, 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 polymer 6 may be provided in any suitable form (e.g., pellets, flakes, sheets, films, etc.) Second polymer 6 may be processed prior to extruding the feed 10 using any suitable method. For example, second polymer 6 may be chopped, shredded, heated, purified, and/or demoistured. In another example, background color may be added to second polymer 6, and then second polymer 6 may introduced into a processing apparatus, such as extruder 15, substantially cold (e.g., without processing) to be mixed with blend 4 and/or into the processing apparatus as close to the extruder die 19 of the processing apparatus as possible to be extruded with blend 4.
Second polymer 6 used may be selected based on its color and/or composition. Second polymer 6 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 fibers 3) that second polymer 6 is being mixed with. For example, crystalline polymers 2, after processing (with or without wood fibers 3 and/or background color 9), may result in a substantially gray color, while second polymer 6, after processing, may result in a substantially black color. Second polymer 6 may have any suitable size, shape, and/or configuration. For example, second polymer 6 may be provided in flake or pellet form.
First polymer 2 and/or second polymer 6 may be melted using any suitable method. For example, first polymer 2 and/or second polymer 6 may be heated using in an external heat source (e.g., a flame in a heater 13) or may be heated through kinetic energy (e.g., by passing through a barrel 12 with a rotating screw 11, or passing through extruder die 19). First polymer 2 and/or second polymer 6 may be melted at any point in the composite manufacturing process prior to forming profile body 1. First polymer 2 and/or second polymer 6 may be heated separately and/or together. In a preferred embodiment, first polymer 2 and/or wood-fibers 3 may be heated and blended to form blend 4. First polymer 2 may be heated substantially throughout first polymer 2 and/or enough to improve processability (e.g., mixing and/or blending).
Wood fibers 3 may be from any type of suitable wood, for example, one or more hardwoods and/or softwoods. Wood fibers 3 may also be mixed with and/or replaced by any organic or inorganic filler such as those set forth herein. Wood fibers 3 may be of any suitable shape and/or size, and may be configured to be suitably blended with first polymer 2 such that a mixture of wood fibers 3 and first polymer 2 appears substantially homogenous in color. Wood fibers 3 may be processed prior to forming profile body 1 using any suitable method. For example, wood fibers 3 may be ground, crushed, chopped, shredded, heated, purified, and/or demoisturized. Wood fibers 3 may be dried prior to being blended with first polymer 2 to form blend 4. In some cases, pieces of wood fiber 3 may be discernible in blend 4, however, wood fiber 3 will still typically have the same homogenous color as the rest of blend 4.
First polymer 2 may be blended in a processor 13 with wood fibers 3 such that blend 4 is substantially homogenous. For example, blend 4 may have one substantially solid color and/or have a substantially uniform consistency. Blend 4 may be formed using any suitable method. First polymer 2 and wood fibers 3 may be blended by placing them together either before, during, or after first polymer 2 and/or wood fibers 3 are dried. First polymer 2 and wood fibers 3 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 polymer 6 may be mixed with first polymer 2 and wood fibers 3 to form a feed 10 in any suitable order, any suitable ratio, and using any suitable method. For example, first polymer 2, second polymer 6, and plurality of wood fibers 3 may be mixed as they are advanced by one or more screws 11 in a barrel 12 and/or extruded through die 19. Second polymer 6 may be mixed with first polymer 2 and wood fibers 3 at any time prior to extruding the feed and in any relative order. For example, first polymer 2 may be blended with wood fibers 3, the blend may be heated, and then second polymer 6 may be added to the blend. In another example, first polymer 2, second polymer 6, and wood fibers 3 may be combined at substantially the same time and mixed simultaneously. Second polymer 6 may be mixed with first polymer 2 and wood fibers 3 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 polymer 6 may be added to blend 4 to form feed 10 just prior to extruding feed 10 through extruder die 19. Thus, heating of second polymer 6 may only occur just after introducing second polymer 6 into blend 4 and/or during extrusion of feed 10 through extruder die 19. Accordingly, second polymer 6 may experience less of a heat history than any of first polymer 2, wood fibers 3, and/or blend 4, 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.) of first polymer 2 and second polymer 6 may assist in preventing the polymers 2, 6, from substantially blending. Exemplary percentages of first polymer 2, second polymer 6, and wood fibers 3 are listed herein, however, generally, the percentage of first polymer 2 will exceed the percentage of second polymer 6.
In various embodiments, composite 1 may include between about 100% and about 20% of first polymer 2, between about 5% and about 0% of second polymer 6, and between about 0% and about 80% wood fiber or other filler. In a preferred embodiment, composite 1 may include between about 60% and about 53% of first polymer 2, about 2% of second polymer 6, 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, composites 1 discussed herein may have other advantages. For example, composite 1 may be less susceptible to mold and mildew and/or may be more durable. First polymer 2 and second polymer 6 do not blend in composites 1. Accordingly, the minor component (in this case, second polymer 6) may migrate to the outer surface 5 of composite 1. When the minor component migrates to outer surface 5 of composite 1, the minor component may tend to coat at least portions of outer surface 5 (e.g., top, bottom, and/or side surfaces) with a polymer rich coating that does not absorb moisture, and thus allows outer surface 5 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 composite 1), may be added to second polymer 6 at any point before or during the manufacturing process of composite 1. During the addition of the additive to second polymer 6, the additive and second polymer 6 may be processed so as to substantially disperse the additive through the matrix of second polymer 6. Once again, because second polymer 6 may migrate to outer surface 5 of composite 1, second polymer 6 with mildew resistant additives (or other materials) may coat at least portions of outer surface 5. Some exemplary reasons why second polymer 6 may migrate toward outer surface 5 of composite 1 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 of composite 1 may have many advantages. For example, the compounds themselves may be relatively expensive and/or including too much of the compound in composite 1 may compromise some structural and/or aesthetic properties of composite 1. Thus, there may be a need to minimize the amount of the compound in composite 1 by delivering the compound to portions of the composite 1 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 of outer surface 5 of composite 1. Accordingly, because the properties (e.g., crystalline structure, solubility, or other properties like or similar to those set forth herein) of first polymer 2 (e.g., crystalline polymer) and second polymer 6 (e.g., amorphous polymer) causes second polymer 6, when extruded, to migrate away from first polymer 2 (e.g., with or without wood fibers 3) and/or toward outer surface 5 of composite 1, second polymer 6 may be used as a vehicle to deliver desirable compounds on and/or toward outer surface 5. In some cases, if the property of the compound is desirable along large portions of outer surface 5, then second polymer 6 with the desirable compound may be disposed along entire portions of outer surface 5, for example, as set forth in FIG. 3C.
Profile body 1 with an outer surface 5 may be formed using any suitable method. For example, the mixture including first polymer 2 (e.g., crystalline polymer), second polymer 6 (e.g., amorphous polymer), and wood fibers 3 may be extruded through a die 19 to form profile body 1. Feed 10 may be extruded using either a single screw extruder or a double screw extruder to form profile body 1. Feed 10 may also be formed into profile body 1 using any suitable method.
Outer surface 5 of profile body 1 may be variegated. Streaks 16 may be formed on outer surface 5 of profile body 1. For example, if first polymer 2 and second polymer 6 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” of second polymer 6 may be dispersed through first polymer 2 and vice versa. As the mixture of second polymer 6 and first polymer 2 (with or without wood fibers 3) is extruded through the die 19, second polymer 6 may tend to go towards outer surface 5 of profile body 1, for example, due the pressures exerted on feed 10 during extrusion. In another example, due to the molecular structure of both first polymer 2 and second polymer 6, the polymer chain of second polymer 6 cannot interlock easily with the polymer chain and/or matrix of first polymer 2. Accordingly, second polymer 6 may tend to separate from the polymer matrix of first polymer 2 and go to outer surface 5 so as to form its own solid polymer matrix of second polymer 6. As second polymer 6 reaches surface 5, because second polymer 6 may have a different initial color and/or different resultant color as the rest of profile body 1 (i.e., blend 4 of first polymer 2 and wood fibers 3), streaks 16 of second polymer 6 may be readily discernible on outer surface 5. Streaks 16 may be generally perpendicular to a cross-section of die 19 through which profile body 1 is extruded. However, streaks 16 may be in any direction, and have any other shape and/or configuration, for example, similar to those set forth in FIGS. 2A-2C. Streaks 16 may form any desired or suitable pattern, for example, a natural-wood-like pattern.
In another example, entire portions of outer surface 5 may be composed of second polymer 6, for example, as shown in FIG. 3C. In such an example, the processing may have been such that second polymer 6 forms “clumps” or “pockets” (e.g., as set forth in the previous paragraph) around substantially all of blend 4 so as to form a substantially solid matrix around blend 4 (e.g., with or without wood fibers 3). Any suitable proportions of second polymer 6, first polymer 2, wood-fibers 3, blend 4, blend 18, background color 9, and another other material or compound set forth herein are contemplated as being discernible on outer surface 5.
The method may also include providing another polymer 7, melting another polymer 7, and mixing another polymer 7 with second polymer 6, first polymer 2, and/or wood fibers 3. With the addition of additional polymer 7, the step of extruding may include forming profile body 1 such that outer surface 5 deliberately evinces a third color different from the first color and the second color due to additional polymer 7.
Another polymer 7 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 of first polymer 2 and/or wood fibers 3. Another polymer 7 may processed and/or behave similarly to other second polymers 6, thus, streaks 16B of another polymer 7 may be formed on outer surface 5 of profile body 1. Streaks 16B from another polymer 7 may be of a color different from either the base color of profile body 1 and/or the color of streaks 16A from second polymer 6.
As shown in FIG. 4B, the method may also include providing a core 8 and forming profile body 1 around at least a portion of core 8. Core 8 may be a wood-plastic composite or any other suitable composite. Core 8 may have a cross-sectional area smaller than a cross-sectional area of die 19. Core 8 may be fed by extruder 15 through die 19 such that core 8 advances through substantially the center of die 19 without contacting any portion of die 19 itself. Extruder 15 and/or die 19 may then deposit an outer surface 5 on core 8 that has more than one color (e.g., variegated and/or streaked) using one or more of the methods set forth herein. The variegated surface 5 may be bonded to core 8 using any suitable method, for example, when variegated surface 5 is co-extruded onto core 8, a portion of core 8 may melt and intermix with variegated surface 5 such that core 8 and the variegated surface 5 are substantially fused. Accordingly, the resultant product may be a building material with a core 8 having a wood-plastic composite having a deliberately variegated outer surface 5 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 a background color 9. As shown in FIG. 4B, background color 9 may be added to first polymer 2 and/or wood fiber 3 (e.g., blend 4) to impart a color to blend 4 different from an initial color of blend 4, first polymer 2, and/or wood fiber 3. Background color 9, first polymer 2, wood fibers 3, and/or blend 4 may be processed by processor 13 using any suitable apparatus and/or method to form resultant blend 14. Resultant blend 14 may then be transferred to extruder 15 and processed with second polymer 6 to form profile body 1 with streaks 16 or other variations of outer surface 5 as set forth herein. Background color 9 may be added to any step of the process and/or any component or subcomponent of the process at any time prior to extrusion through die 19.
In a preferred embodiment, as shown in FIG. 4C, background color 9 may be added to second polymer 6 to impart a color to second polymer 6 different from an initial color of second polymer 6. Background color 9 and/or second polymer 6 may be processed by processor 17 using any suitable apparatus and/or method to form resultant blend 18 of second polymer 6 and background color 9. Resultant blend 18 may then be transferred to extruder 15 and processed with first polymer 2, wood fibers 3, and/or blend 4 to form profile body 1 with streaks 16 or other variations of outer surface 5 as set forth herein. Once again, background color 9 may be added to any step of the process and/or any component or subcomponent of the process at any time prior to extrusion through die 19.
In another preferred embodiment, as shown in FIGS. 4D and 4E, first polymer 2 and plurality of wood fibers 3 may be processed (e.g., dried and/or pre-melted) using any suitable apparatus and/or method to form blend 4. Background color 9 may be added to first polymer 2 and/or wood fiber 3 (e.g., blend 4) to impart a color to blend 4 different from an initial color of blend 4, first polymer 2, and/or wood fiber 3. Background color 9, first polymer 2, wood fibers 3, and/or blend 4 may be processed by processor 13 using any suitable apparatus and/or method to form resultant blend 14. Background color 9, first polymer 2, and/or wood fiber 3 may mixed together and/or processed at substantially the same time to form resultant blend 14 without first forming blend 4, or background color 9 may be added to blend 4 after the processing of first polymer 2 and/or wood fiber 3 has already begun and/or has been completed. Resultant blend 14 may then be transferred to extruder 15.
Second polymer 6 may then be added to resultant blend 14 and/or feed 10 that is now disposed in extruder 15. Second polymer 6 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 polymer 6 may be added to any portion of resultant blend 14 and/or feed 10 disposed in any portion of extruder 15, barrel 12, and/or screw 11. For example, second polymer 6 may be added through a vent port 20 disposed on a side of extruder 15 and/or barrel 12. Vent port 20 may be disposed at approximately a halfway position along a length of extruder 15, barrel 12, and/or screw 11, which may be a low-pressure region relative to the rest of extruder 15. Vent port 20 may be disposed downstream from a blister 11 b on screw 11, which may cause region of extruder 15 adjacent to vent port 20 to be a low pressure region. Vent port 20 may be connected to a side feeder 21, for example, as shown in FIGS. 4D and 4E.
Side feeder 21 may include a feed screw 22 driven by a variable speed motor drive 23. A barrel 24 may surround feed screw 22 near vent port 20 and may be connected to an outer surface of extruder 15. Feed screw 22 may be disposed such that feed screw 22 places second polymer 6 into extruder 15 without forcing second polymer 6 into screw 11. Feed screw 22 and screw 11 do not contact each other.
Barrel 24 (e.g., also called an extruder vent stack) may include a vacuum section 26 configured to remove impurities from second polymer 6 disposed in barrel 24, for example, turpentine and/or organic materials. This may prevent foaming later in the process. A distal end 27 of barrel 24 may include a door 28. Door 28 may be configured to allow second polymer 6 to be placed therethrough into an interior of barrel 24 such that second polymer 6 may be fed into extruder 15.
Distal to barrel 24 may be basket 31. Basket 31 may be configured to receive second polymer 6 in any suitable form, for example, unmelted pellets. A hose 29 may connect an outlet of basket 31 to door 28 so as to allow second polymer 6 to be advanced from basket 31 to door 28. Hose clamp 30 may connect hose 29 to each of door 28 and the outlet of basket 31. Hose clamp 30 may form a substantially airtight seal between door 28, hose 29, basket 31, and/or barrel 24. Basket 31 may include a lid 32 disposed on a gasket disposed around an upper end of basket 31. Lid 32 may be configured to maintain a substantially airtight seal with basket 31, for example, to maintain a desired air pressure in basket 31. A desired air pressure may be an air pressure above that in barrel 24 so as to assist in moving second polymer 6 from basket 31, through hose 29, and into barrel 24. Lid 32 may include a vent 33, for example a ¼ turn ball valve, to assist in maintaining a desired air pressure in basket 31. Barrel 24 may extend distal to door 28, under basket 31, and/or to motor 23. Barrel 24 in this region may have a smaller cross-sectional area (e.g., diameter) relative to the region of barrel 24 adjacent to vent port 20. A lip seal 34 may provide a substantially airtight seal between feed screw 22 and barrel 24. Any cracks or gaps between any portions of side feeder 21 (e.g., between basket 31, feed screw 22, lip seal 34, barrel 24, door 28, hose 29, and/or hose clamp 30) may be sealed with a sealant, for example, silicon caulk.
Side feeder 21 may be disposed on an adjustable table 35, for example, to adjust the height of side feeder 21 relative to extruder 15. This adjustablility may be desirable, for example, to locate side feeder 21 at an ideal height such that second polymer 6 flows into barrel 12 of extruder 15 at a desired rate and/or at a desired location (e.g., into barrel 12 without exerting excessive force on screw 11 which may cause excessive mixing of second polymer 6 with resultant blend 14 and/or feed 10). A longitudinal axis of side feeder 21, barrel 24, and/or feed screw 22 may be substantially parallel to the ground and/or substantially perpendicular to a longitudinal axis of screw 11, extruder 15, and/or barrel 12.
Once second polymer 6 has been introduced into resultant blend 14 and/or feed 10, second polymer 6 may mix, but not blend, with resultant blend 14 and/or feed 10 and may be extruded into composite 1 via extruder die 19. Composite 1 may have a variegated outer surface 5 and/or streaks 16.
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 polymer 2, second polymer 6, and/or third polymer 7. 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, composite 1 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 polymer 2 and wood fibers need not be blended prior to mixing them with second polymer 6.
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

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 of claim 1, wherein the first polymer is at least one of polypropylene and polyethylene.

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

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

5. The composite of claim 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 of claim 1, wherein the outer surface is variegated.

7. The composite of claim 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 of claim 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 of claim 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 of claim 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 of claim 11, further comprising forming streaks of the second polymer on the outer surface.

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

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

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

16. The method of claim 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 of claim 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 of claim 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 of claim 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 of claim 11, further comprising providing a colorant; and

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

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

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

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

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