U.S. patent application number 11/638800 was filed with the patent office on 2007-06-28 for tri-excluded wucs glass fiber reinforced plastic composite articles and methods for making such articles.
Invention is credited to Ashish Diwanji, Kevin S. Guigley, Ralph D. McGrath, Michael A. Strait, Teresa L. Wagner, Douglas H. Walden.
Application Number | 20070148429 11/638800 |
Document ID | / |
Family ID | 39432511 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070148429 |
Kind Code |
A1 |
McGrath; Ralph D. ; et
al. |
June 28, 2007 |
Tri-excluded WUCS glass fiber reinforced plastic composite articles
and methods for making such articles
Abstract
Disclosed are a series of composite polymer composite structures
formed by the coextrusion of at least two distinct polymeric
components. A first polymeric component includes a structural
composition and a second polymeric component includes a coating
composition. The primary structural frame formed from the
structural composition includes at least one longitudinal recess.
These recesses may be filled with a third polymeric composition
that may include wood byproducts and/or a blowing agent. The first
polymeric component may include reinforcing fibers at least
partially coated with a size composition that includes a film
forming agent, a lubricant, one or more additives, and first and
second coupling agents. The additives may be chosen to achieve
selective or desired properties in the end product. The inclusion
of additives to the reinforcing fiber enhances the fiber
reinforcements and enables the production of reinforced composite
articles having a desired combination of size, strength,
appearance, and/or functionality.
Inventors: |
McGrath; Ralph D.;
(Granville, OH) ; Strait; Michael A.; (Johnstown,
OH) ; Guigley; Kevin S.; (Granville, OH) ;
Walden; Douglas H.; (Newark, OH) ; Wagner; Teresa
L.; (Granville, OH) ; Diwanji; Ashish; (New
Albany, OH) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
39432511 |
Appl. No.: |
11/638800 |
Filed: |
December 14, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11311749 |
Dec 19, 2005 |
|
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11638800 |
Dec 14, 2006 |
|
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Current U.S.
Class: |
428/292.1 |
Current CPC
Class: |
C08J 5/08 20130101; Y10T
428/249924 20150401; C03C 25/26 20130101; B29C 48/21 20190201; B29K
2105/06 20130101; B29C 48/0016 20190201; B29C 48/06 20190201; B29C
48/304 20190201; B29C 48/09 20190201; B29C 48/154 20190201; B29C
48/12 20190201; B29C 48/07 20190201; B29C 48/022 20190201; B29C
48/11 20190201 |
Class at
Publication: |
428/292.1 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Claims
1. A reinforced composite article comprising: an elongated primary
structural frame having a longitudinal recess, said elongated
primary structural frame formed from a first polymeric composition
that includes glass fibers, each glass fiber having a surface at
least partially coated with a sizing composition containing a film
forming agent, a lubricant, one or more first additives, a first
coupling agent to enhance the interface between said first
polymeric composition and said surfaces of said glass fibers, and a
second coupling agent to enhance the interface between said first
polymeric composition and the boundary between said primary
structural frame and said longitudinal recess when said
longitudinal recess contains natural fibers; a second polymeric
composition filling said longitudinal recess; and a third polymeric
composition forming a capping layer on a major surface of said
primary structural frame.
2. The reinforced composite article of claim 1, wherein said first
coupling agent is present on said glass fiber in an amount from
about 1.5 to about 2.5% by weight and said second coupling agent is
present on said glass fiber in an amount from about 0.5 to about
1.0% by weight.
3. The reinforced composite article of claim 1, wherein said film
forming agent is at least one member selected from the group
consisting of a polyurethane film former, a polyester film former,
a polyolefin film former, a modified functionalized polyolefin and
an epoxy resin film former, and said first and second coupling
agents are silane coupling agents selected from the group
consisting of aminosilanes, silane esters, vinyl silanes,
methacryloxy silanes, epoxy silanes, sulfur silanes, ureido silanes
and isocyanato silanes.
4. The reinforced composite article of claim 1, wherein said one or
more first additives is at least one member selected from the group
consisting of fire retardants, UV stabilizers, processing aids,
antioxidents, mold inhibiting agents, lubricants, colorants,
coupling agents, sealants, friction modifiers, color stabilizers,
IR reflectors, smoke suppressors, pigments, biocides, dyes,
additives to improve surface feel, additives to reduce roughness
and additives to improve abrasion resistance.
5. The reinforced composite article of claim 1, wherein said first
additives are dispersed substantially evenly throughout said
primary structural frame.
6. The reinforced composite article of claim 1, wherein said glass
fibers are wet use chopped strand glass fibers having a moisture
content of at least about 5 wt %.
7. The reinforced composite article of claim 1, wherein: said
second polymeric composition includes a filler selected from the
group consisting of wood flour, wood fibers, calcium carbonate,
talc, magnesium hydroxide and gypsum; and said third polymeric
composition includes a second additive selected from the group
consisting of UV stabilizers, color stabilizers, IR reflectors,
fire retardants, smoke suppressors, lubricants, pigments, biocides
and dyes.
8. The reinforced composite article of claim 1, wherein said second
polymeric composition is a foam.
9. A high performance reinforcing fiber for a reinforced plastic
composite article: a glass fiber having a surface at least
partially coated with a sizing composition containing a film
forming agent, a lubricant, one or more additives, a first coupling
agent to enhance the interface between a first polymeric
composition and said surface of said glass fiber, and a second
coupling agent to enhance the interface between said first
polymeric composition and the surfaces of natural fibers.
10. The reinforcing fiber of claim 9, wherein said film forming
agent is at least one member selected from the group consisting of
a polyurethane film former, a polyester film former, a polyolefin
film former, a modified functionalized polyolefin and an epoxy
resin film former, and said first and second coupling agents are
silane coupling agents selected from the group consisting of
aminosilanes, silane esters, vinyl silanes, methacryloxy silanes,
epoxy silanes, sulfur silanes, ureido silanes and isocyanato
silanes.
11. The reinforced composite article of claim 9, wherein said first
coupling agent is present on said glass fiber in an amount from
about 1.5 to about 2.5% by weight and said second coupling agent is
present on said glass fiber in an amount from about 0.5 to about
1.0% by weight.
12. The reinforced composite article of claim 9, wherein said one
or more additives includes at least one member selected from the
group consisting of fire retardants, UV stabilizers, processing
aids, antioxidents, mold inhibiting agents, lubricants, colorants,
coupling agents, sealants, friction modifiers, color stabilizers,
IR reflectors, smoke suppressors, pigments, biocides, dyes,
additives to improve surface feel, additives to reduce roughness
and additives to improve abrasion resistance.
13. A method of manufacturing a reinforced composite article
comprising: coextruding: a first polymeric composition to form a
primary structural frame having a longitudinal recess, said first
polymeric composition including glass fibers, each glass fiber
having a surface at least partially coated with a sizing
composition containing a film forming agent, a lubricant, one or
more first additives, a first coupling agent to enhance the
interface between said first polymeric composition and said
surfaces of said glass fibers, and a second coupling agent to
enhance the interface between said first polymeric composition and
the boundary between said primary structural frame and said
longitudinal recess when said longitudinal recess contains natural
fibers, a second polymeric composition to substantially fill said
longitudinal recess, and a third polymeric composition to form a
surface layer on a major surface of said primary structural frame
and form a reinforced composite article.
14. The method of claim 13, wherein said film forming agent is at
least one member selected from the group consisting of a
polyurethane film former, a polyester film former, a polyolefin
film former, a modified functionalized polyolefin and an epoxy
resin film former, and said first coupling agent is an aminosilane
coupling agent.
15. The method of claim 13, wherein said one or more first
additives includes at least one member selected from the group
consisting of fire retardants, UV stabilizers, processing aids,
antioxidents, mold inhibiting agents, lubricants, colorants,
coupling agents, sealants, friction modifiers, color stabilizers,
IR reflectors, smoke suppressors, pigments, biocides, dyes,
additives to improve surface feel, additives to reduce roughness
and additives to improve abrasion resistance.
16. The method of claim 13, wherein said one or more first
additives are dispersed substantially evenly throughout said
primary structural frame.
17. The method of claim 13, wherein: said second polymeric
composition includes a filler selected from the group consisting of
wood flour, wood fibers, calcium carbonate, talc, magnesium
hydroxide and gypsum; and said third polymeric composition includes
at least one second additive selected from the group consisting of
UV stabilizers, color stabilizers, IR reflectors, fire retardants,
smoke suppressors, lubricants, pigments, biocides and dyes.
18. The method of claim 13, wherein said second polymeric
composition is a foam.
19. The method of claim 13, wherein said reinforcing fibers are wet
use chopped strand glass fibers having a moisture content of at
least about 5 wt %.
20. The method of claim 13, wherein said first and second coupling
agents are silane coupling agents selected from the group
consisting of aminosilanes, silane esters, vinyl silanes,
methacryloxy silanes, epoxy silanes, sulfur silanes, ureido silanes
and isocyanato silanes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation-in-Part of U.S. patent
application Ser. No. 11/311,749 entitled "Tri-Extruded WUCS Glass
Fiber Reinforced Plastic Composite Articles And Methods For Making
Such Articles" filed Dec. 19, 2005, the entire content of which is
expressly incorporated herein by reference in its entirety.
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
[0002] The present invention relates to tri-extruded composite
articles, and more particularly, to a sizing composition for
reinforcing fibers used in tri-extruded reinforced composite
articles where the sizing composition includes additives to achieve
desired physical or structural attributes.
BACKGROUND OF THE INVENTION
[0003] Wood fibers, especially fibers from waste wood generated
during the production of dimensional lumber or the milling or
shaping of wood substrates, in combination with one or more
polymeric adhesives, have long been used in the production of
composite materials such as oriented strand board (OSB) and
particleboard. OSB products, for example, can be manufactured by
combining wood fibers with urea, phenol, and melamine resin binders
to form an intermediate product. This intermediate product is then
subjected to relatively high pressures and/or temperatures to
compress and cure the mixture and obtain the final OSB product.
Although this process is generally suitable for forming large
planar sheets, it is less suitable for forming composite products
that have complex profiles and/or otherwise formed portions.
[0004] In addition, wood fiber and strand thickness and length
typically utilized in producing OSB products are generally less
suitable for products intended for applications in which mechanical
forces must be transmitted more uniformly throughout the composite
product. Indeed, the variations in the diameter and length of the
wood fibers incorporated into the OSB products tend to produce
regions of high pressure and low pressure that render such products
generally unsuitable for articles subjected to bending
stresses.
[0005] Particleboard is manufactured using a process similar to
that used to manufacture OSB but, rather than using wood fibers or
stands, particleboard is manufactured using fine wood particles as
its main structural component. The use of conventional binders
and/or adhesives similar to those used in the manufacture of OSB
typically requires the application of very high pressures and an
elevated temperature to compress and cure the mixture to produce
the final product. The structural limitations associated with
particleboard, particularly its reduced strength relative to
corresponding thicknesses of OSB and plywood products, its tendency
to absorb water, and its increased density render it unsuitable for
many applications, particularly exposed applications or those in
which significant loads are anticipated.
[0006] Other methods have been developed to utilize wood fiber in
making shaped articles having drawn portions, such as pallets,
rather than more planar articles such as decking or sheeting. Such
pallets typically include a flat support surface with a plurality
of projections extending below the support surface for contacting
the floor or shelving on which the pallet is placed. Such pallets
are typically manufactured from a variety of wood fibers,
particularly those typically found in paper mill effluent streams,
usually in combination with one or more filler materials, for
example clay, and/or longer wood fibers from one or more secondary
sources. The wood fibers are typically bonded using one or more
thermosetting resins, for example phenolformaldehyde,
resorcinol-formaldehyde, melamine-formaldehyde, urea-formaldehyde,
urea-furfural and condensed furfuryl alcohol resin and organic
polyisocyanates.
[0007] The bonding performance of isocyanates can be highly
dependent upon the density and porosity of the bonded materials.
Therefore, when isocyanates are utilized, a preferred practice is
to limit the size and density distribution within the mixture of
wood fibers that are being processed into the drawn articles. This
limitation can result in an acute disadvantage in systems that
obtain waste wood from many different sources. The use of these
isocyanate binding agents may also raise environmental and
workplace safety issues. These compositions also tend to exhibit
only limited moisture protection and do not tend to exhibit uniform
strength characteristics throughout their load bearing
portions.
[0008] Molded pallets and platforms may also incorporate one or
more plastic compositions, typically either as a coating applied
over a wood or cellulosic fiber matrix or as an additive to a wood
pulp slurry. While the products produced by incorporating one or
more plastics may exhibit improved moisture resistance, such
articles continue to suffer from either the strength limitations
referenced above or by requiring an intricate and complex forming
process. In some situations, plastic is added only as a coating in
the final forming stages of the article, and thus does not tend to
impart significant bonding, strength, and other desirable
characteristics that can be achieved when appropriate plastic
formulations are utilized in composite products as a primary
structural component and/or as a bonding agent.
[0009] Additionally, the conventional methods which utilize wood
fibers in some capacity to form a finished composite article do not
tend to utilize the waste wood supply in any substantive manner,
with portions of the waste wood typically being incinerated, used
as fuel in an electrical cogeneration facility or buried in a
landfill. Many of the conventional methods utilize either paper
mill sludge as a source for wood fibers or are resigned to being
dependent on the arrival of a sufficient raw wood supply which is
consistent in the same type of wood utilized previously
utilized.
[0010] Other efforts to produce composite structural materials
incorporating waste wood involves combining the cellulosic fibers
from the waste wood with particles of one or more plastics such as
high density polyethylene (HDPE) or low density polyethylene (LDPE)
to form a composite mixture. The length of fiber or flake and the
type of plastic selected are dependent upon the material
characteristics desired in the finished product. A coupling agent
may be added to the mixture as the cellulosic fibers and the
plastic(s) are being blended together, thereby enhancing the
intended properties in the finished article.
[0011] This composite material mixture may then be deposited onto a
mold to form a mat or charge of the composite material on the mold.
Depending on the manner in which the composite material is applied
to the mold, some control over the fiber orientation within the
mold. The composite material mixture is then typically subjected to
a combination of heat and pressure sufficient to force the plastic
throughout the fibers to fill substantially all voids and
interstices.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide a
reinforced composite article that includes an elongated primary
structural frame having a longitudinal recess, a second polymeric
composition that fills the longitudinal recess, and a third
polymeric composition that forms a capping layer on a major surface
of the primary structural frame. The primary structural frame is
formed from a first polymeric composition that includes reinforcing
fibers at least partially coated with a sizing composition that
contains a film forming agent, a coupling agent, a lubricant, one
or more additives, a first coupling agent to enhance the interface
between the first polymeric composition and the surface of the
glass fibers, and a second coupling agent to enhance the interface
between the first polymeric composition and the boundary between
the primary structural frame and the longitudinal recess when the
longitudinal recess contains natural fibers. The additive(s) in the
size formulation may be selected to make the reinforcing fiber more
compatible with the resin matrix or to provide a mechanical or
visual property. Examples of suitable additives include, but are
not limited to, fire retardants, UV stabilizers, processing aids,
antioxidents, mold inhibiting agents, lubricants, colorants,
coupling agents, sealants, friction modifiers, color stabilizers,
IR reflectors, smoke suppressors, pigments, biocides, dyes,
additives to improve surface feel and/or roughness, and additives
to reduce abrasion resistance. Because the additives are added with
the size composition directly onto the reinforcement fibers, the
additives may be incorporated at a reduced or optimal level.
Additionally, the inclusion of additives to the size composition
permits for the customization of product-specific sizing
compositions tailored to achieve desired physical or structural
attributes. Further, the additives may be dispersed substantially
evenly throughout the primary structural frame by including the
additives as part of the sizing composition.
[0013] It is another object of the present invention to provide a
high performance reinforcing fiber. The reinforcing fiber is a
glass fiber at least partially coated with a sizing composition
that contains a film forming agent, a first coupling agent, a
lubricant, one or more additives, a first coupling agent to enhance
the interface between the first polymeric composition and the
surface of the glass fiber, and a second coupling agent to enhance
the interface between the first polymeric composition and the
surface of natural fibers. The additive(s) in the size formulation
may be selected to make the glass fiber more compatible with the
resin matrix or to provide a mechanical or visual property.
Examples of suitable additives include fire retardants, UV
stabilizers, processing aids, antioxidents, mold inhibiting agents,
lubricants, colorants, coupling agents, sealants, friction
modifiers, color stabilizers, IR reflectors, smoke suppressors,
pigments, biocides, dyes, additives to improve surface feel and/or
roughness, and additives to reduce abrasion resistance.
[0014] It is yet another object of the present invention to provide
method of manufacturing a reinforced composite article that
includes coextruding a first polymeric composition including
reinforcing fibers having thereon a sizing composition that
contains one or more additives that include a first coupling agent
to enhance the interface between the first polymeric composition
and the surface of the glass fibers, and a second coupling agent to
enhance the interface between the first polymeric composition and
the boundary between the primary structural frame and the
longitudinal recess when the longitudinal recess contains natural
fibers, a second polymeric composition, and a third polymeric
composition to form a composite article. In the reinforced
composite article, the first polymeric composition forms a primary
structural frame that has a first longitudinal recess, the second
polymeric composition substantially fills the first longitudinal
recess, and the third polymeric composition forms a surface layer
on a major surface of the primary structural frame. The second
polymeric composition may include a filler such as wood flour, wood
fibers, calcium carbonate, talc, magnesium hydroxide, and gypsum.
Examples of suitable additives include, but are not limited to,
fire retardants, UV stabilizers, processing aids, antioxidents,
mold inhibiting agents, lubricants, colorants, coupling agents,
sealants, friction modifiers, color stabilizers, IR reflectors,
smoke suppressors, pigments, biocides, dyes, additives to improve
surface feel and/or roughness, and additives to reduce abrasion
resistance. Because the additives are added with the size
composition onto the reinforcement fibers, the additives may be
dispersed substantially evenly throughout the primary structural
frame. The third polymeric composition may include at least one
second additive such as UV stabilizers, color stabilizers, IR
reflectors, fire retardants, smoke suppressors, lubricants,
pigments, biocides and/or dyes.
[0015] It is an advantage of the present invention that the
inclusion of additives to the size composition permits for the
customization of product-specific sizing compositions tailored to
achieve desired physical or structural attributes.
[0016] It is another advantage of the present invention that
utilizing the reinforcing fibers as a carrier for desired additives
may result in an overall improvement in the performance of the
products formed from the additive-sized reinforcement fibers.
[0017] It is yet another advantage of the present invention that
incorporating additives into the size composition and onto the
reinforcement fibers may aid the dispersion of the additives
substantially evenly throughout the polymer matrix.
[0018] It is a further advantage of the present invention that by
applying desired additives directly to the reinforcement fibers,
the additives can be expected to more effectively enhance the
interface between the resin and the surface of the reinforcement
fibers.
[0019] It is also an advantage of the invention that because the
additives are added with the size composition directly onto the
reinforcement fiber, they may be incorporated at a reduced or
optimal level.
[0020] It is a feature of the present invention that the
application of desired additives to the reinforcing fiber with the
sizing composition may result in a reduction in the amount of
wasted additives and manufacturing costs.
[0021] It is another feature of the invention that the efficacy of
the reinforcing fiber in terms of its inherent reinforcing
capability may be enhanced with the inclusion of the additives into
a sizing formulation.
[0022] The foregoing and other objects, features, and advantages of
the invention will appear more fully hereinafter from a
consideration of the detailed description that follows. It is to be
expressly understood, however, that the drawings are for
illustrative purposes and are not to be construed as defining the
limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The advantages of this invention will be apparent upon
consideration of the following detailed disclosure of the
invention, especially when taken in conjunction with the
accompanying drawings wherein:
[0024] FIG. 1 is a schematic illustration of process equipment
arranged to support the process for manufacturing flow according to
at least one exemplary embodiment of the present invention;
[0025] FIGS. 2A-2C are representative cross-sections along planes
A-A, B-B and C-C respectively of various exemplary embodiments of
composite products manufactured by the equipment depicted in FIG.
1;
[0026] FIGS. 2D-2F are representative cross-sections along plane
C-C of a composite product manufactured on the equipment depicted
in FIG. 1;
[0027] FIG. 3 is a schematic illustration of process equipment
arranged to support the process for manufacturing flow according to
another exemplary embodiment of the present invention;
[0028] FIGS. 4A-4C are representative cross-sections along planes
A-A, B-B and C-C respectively, of a composite product manufactured
by the equipment depicted in FIG. 3;
[0029] FIG. 4D is a representative cross-section along plane C-C of
a composite product manufactured on the equipment depicted in FIG.
3;
[0030] FIG. 5 is a schematic illustration of process equipment
arranged to support the process for manufacturing flow according to
yet another exemplary embodiment of the present invention;
[0031] FIGS. 6A-6E are representative cross-sections along plane
A-A (FIG. 6A) and along plane B-B (FIGS. 6B-6E) of a composite
product manufactured on the equipment depicted in FIG. 5;
[0032] FIG. 7 is a schematic illustration of process equipment
arranged to support the process for manufacturing flow according to
a further exemplary embodiment of the present invention;
[0033] FIGS. 8A-8D are representative cross-sectional and plan
views illustrating surface finishing treatments of various
embodiments of composite articles manufactured according to
exemplary embodiments of the present invention; and
[0034] FIGS. 9A-9E are representative cross-sectional views of
various embodiments of composite articles manufactured according to
exemplary embodiments of the present invention.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
[0035] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are described
herein. All references cited herein, including published or
corresponding U.S. or foreign patent applications, issued U.S. or
foreign patents, or any other references, are each incorporated by
reference in their entireties, including all data, tables, figures,
and text presented in the cited references.
[0036] In the drawings, the thickness of the lines, layers, and
regions may be exaggerated for clarity. It is to be noted that like
numbers found throughout the figures denote like elements. The
terms "size", "sizing", and "size composition" may be used
interchangeably herein. In addition, the terms "film former" and
film forming agent" may be used interchangeably. Further, the terms
"composition" and "formulation" may be used interchangeably
herein.
[0037] It is anticipated that composite articles manufactured
according to the invention will be suitable for applications
including, for example, residential and commercial building
applications, residential and commercial decking; residential and
commercial fence and railing systems; docks and slipways;
residential and commercial exterior finishing or cladding products;
residential interior structural finishing and cladding products,
alternatives to dimensional lumber in some applications; and
infrastructure products such as highway sound control barriers.
[0038] The use and incorporation of glass fibers will tend to
improve resistance to moisture uptake, which in turn could enhance
resistance to mold and mildew. The increased strength, particularly
with regard to materials suitable for residential and commercial
decking could allow for increased spans which in turn would reduced
the level of supporting structure required to build a structurally
equivalent assembly.
[0039] With regard to the glass composition itself, the present
invention will typically incorporate glass coupling agents and
possibly other additives and processes for improving the
incorporation and adhesion of the glass fibers within the composite
article. The glass fiber may comprise up to about 40 wt. %, but
more typically 15-30 wt. %, of one or more elements of the final
composite article and may be combined with other elements that are
substantially free of glass fibers. This invention also provides
methods for glass fiber handling and delivery that allow for
improved introduction of discrete glass fibers into abroad range of
composite materials during the manufacturing process.
[0040] As noted above, composite articles fabricated in accord with
the invention, particularly those that incorporate wet fibers
(e.g., wet use chopped strand glass fibers (WUCS)) or other
components that initially include or subsequently release water may
incorporate one or more water scavengers. For example, in the
course of preparing a polymeric component with WUCS for subsequent
inclusion in a composite article can utilize gypsum particles as a
filler that will tend to scavenge the water present in the wet
glass fibers. Utilizing this scavenging function of the gypsum
filler in one or more of the components used to form the composite
article tends to reduce or eliminate the need for subsequent
venting or drying that was previously necessary to remove water
from the component(s) as steam during the subsequent elevated
temperature molding and/or forming operation(s). In this respect,
the gypsum filler functions as both a processing aid and as a
filler that will tend to increase the bulk of the composite
articles and improve their fire resistance.
[0041] The invention also encompasses the use of one or more
polymer coupling agents to enhance the surface bond between not
just the glass and resin, but also in the event that wood fibers or
particles are used in combination with glass fibers, the surface
bond between adjacent wood fibers or particles. It is anticipated
that both recycled, post-consumer, and virgin thermoplastic resins
may be used successfully in manufacturing embodiments of the
composite articles according to the invention. Further, although
the composite articles and the associated methods of manufacture
according to the invention are expected to utilize predominately
extrusion processes, it is anticipated that some compositions
within the scope of the invention would have properties suitable
for use in injection molding processes as well and may be suitable
for use in combination with premanufactured films, layers, or
inserts.
[0042] In most instances, it is expected that modified polyolefin
polymers will be suitable for use as coupling agents applied to the
glass substrate before the fibers are blended with the other
components of the composite material. These polymers include, for
example, maleic grafted polypropylene, polyethylene and
polypropylene-polyethylene copolymers, ethoxylated polypropylene,
polyethylene and polypropylene-polyethylene copolymers, and
ethylene acrylic functional polypropylene, polyethylene and
polypropylene-polyethylene copolymers. These additives, when
applied to the glass in aqueous form prior to blending with other
components, act as adhesion promoters to improve the mechanical
properties of wood plastic composites.
[0043] Embodiments of the invention may include the use of glass
fibers and maleic anhydride grafted polyethylene and polypropylene
polymers in tandem to improve the mechanical properties of wood
plastic composites. Exemplary reinforced compositions will include
between about 25 wt. % to about 45 wt. % polymer, between about 25
wt. % to about 45 wt. % wood fiber and/or wood flour, and about 5
wt. % to about 40 wt. % fiberglass, preferably WUCS. The coupling
agent(s), for example maleic grafted polymer(s), may be used with
the fiberglass in weight ratios between about 1:5 and 1:40 relative
to each other. Using these components in these formula ratios will
tend to improve the effectiveness of the fiberglass
reinforcements.
[0044] The incorporation of wood fibers, wood flour and/or other
organic fibers and fillers will be improved through the use of an
appropriate compatibilizer. Exemplary compatibilizers include
copolymers that provide a coupling function among various
components of the composite material and/or can change the chemical
environment of the compositions used to form the composite article
that allows the various components to be more easily and/or
uniformly dispersed to form a more stable composite. The specific
manner in which the compatibilizer functions is not critical, but
typically improved coupling functionality relative to conventional
coupling agents is preferred.
[0045] A compatibilizer (or compatibilizing copolymer) typically
represents a copolymerization reaction product of an olefin and at
least one other comonomer. It is expected that a range of olefins
can be used singly or in combination in practicing the invention
including, for example, ethylene, propylene, isomers of butylene,
and/or other common olefins of the type widely used in conventional
polymerization reactions employing traditional (Zieglar-Natta)
catalysts and/or more specific metallocene catalysts.
[0046] Useful compatibilizers are those that include a functional
comonomer (e.g., a monomer that can be copolymerized with a
suitable olefin under conditions suitable for
olefin-polymerization) that includes an anhydride functionality. An
exemplary functional comonomer is maleic anhydride and its general
functional equivalents such as maleic anhydride derivatives such as
maleic acid and/or its salts; maleic acid diesters or monoesters,
including esters of C.sub.1-C.sub.4 alcohols, such as, for example,
methyl, ethyl, n-propyl, isopropyl, and n-butyl alcohols; itaconic
acid; fumaric acid; fumaric acid monoester; and mixtures thereof.
Of particular note with regard to the selection of appropriate
compatibilizers are maleic anhydride and its monoesters and/or
diesters.
[0047] Useful compatibilizers also include terpolymers of ethylene
(E); maleic anhydride and/or it chemical equivalents; and a third
comonomer, X, selected from a group including, for example, vinyl
acetate, (meth)acrylic acid, and/or derivatives thereof. Suitable
derivatives of (meth)acrylic acid include salts, esters,
anhydrides, or other acid derivatives are known to one of ordinary
skill in the chemical arts including preferred acid derivatives
including, for example, methyl acrylate and/or butyl acrylate.
[0048] Compatibilizers may be present in those components of the
composite article that incorporate wood and/or other organic
materials an amount of about 0.1 to about 10 wt. % based on the
total weight of the composition. Preferably the compatibilizer is
present in an amount of from about 0.25 wt. % to about 5 wt. %,
more preferably in an amount of from about 1 wt. % to about 4 wt.
%. As will be appreciated by those skilled in the art, the
concentration of compatibilizer necessary to obtain a desired
result will be a function of the polymers used, the type of organic
material being incorporated, and the particular compatibilizer(s)
being utilized.
[0049] One or more compatibilizers, particularly those including
higher concentrations of the functional comonomer(s), can be
blended with other polymeric materials to dilute the concentration
of the functionality and thereby provide a blended composition for
use in various types of wood composite materials.
[0050] As suggested above, a wide variety of cellulosic and other
fibrous and/or filler materials may be utilized in the present
invention. Cellulosic materials for use in the present invention
may be obtained from wood and wood products, such as wood pulp
fibers; non-woody paper-making fibers from cotton; recycled paper
materials; straws and grasses, such as rice and esparto; canes and
reeds, such as bagasse; bamboos; stalks with bast fibers including,
for example, jute, flax, kenaf, cannabis, linen and ramie; and leaf
fibers, such as abaca and sisal. The cellulosic materials can be
used singly or in combination.
[0051] Wood and wood products may be especially suitable for
inclusion in one or more of the polymeric components of the
composite articles according to the invention. Suitable wood
sources will typically include softwood sources such as pines,
spruces, and firs, and hardwood sources such as oaks, maples,
eucalyptuses, poplars, beeches, and aspens. The form of the
cellulosic materials from wood sources, particularly waste wood
sources, can be incorporated into the polymeric components as one
or more of sawdust, wood chips, wood flour and/or wood fibers.
[0052] As will be appreciated, in addition to wood products,
cellulosic materials obtained from other agricultural residues
and/or industrial waste can be incorporated into one or more of the
polymeric components used in forming a composite article according
to the invention. Examples agricultural residues will include, for
example, the residue remaining after harvesting wheat, rice, corn
and/or other grain stocks such as straw; corn stalks; rice hulls;
wheat; oat; barley and oat chaff; coconut shells; peanut shells;
walnut shells; jute; hemp; bagasse; bamboo; flax; and kenaff; and
combinations thereof. Additional discussion of these materials and
other components that may be incorporated in the composite articles
according to the invention may be found in WO 05/080496, published
Sep. 1, 2005, the disclosure of which is incorporated by reference
in its entirety.
[0053] One or more of the polymeric components that comprise a
composite article according to the invention, particularly exposed
components, may include one or more fire retardants such as
magnesium hydroxide, zinc borate, and gypsum (hydrated calcium
sulfate). These additives may either be used in a specific region
or component, for example, a capstock, as in the case of a multiple
extrusion, or as an additive incorporated in a gelcoat, e.g., a
typically quick-setting resin used in molding processes for
providing an improved surface for the composite. In molding
processes, the gelcoat may be the first resin applied to the mold
after the mold-release agent, thereby becoming an integral part of
the finished composite article.
[0054] Alternatively, one or more additives may be distributed
throughout the entire product with the various polymeric components
having similar or substantially different effective concentrations
of the additives depending on the functional results of the
additive and the need for that function in the particular polymeric
component. For example, UV stabilizers will more likely be
concentrated in one or more surface layers while processing aids
for foaming agents may be found only in internal reduced density
components.
[0055] In a further embodiment of the present invention, one or
more additives may be applied to the glass fiber with a sizing
composition during fiber formation. The application of additives to
the glass fiber enhances the glass fiber reinforcements, enabling
the production of composite articles having a desired combination
of size, strength, appearance, and/or functionality.
Conventionally, additives are added in masterbatches, which are
inherently wasteful due to losses associated with job start-up, job
change, and shut down. By applying desired additives directly onto
the glass fibers, which would, in turn, be added directly to the
extruder after the extrusion process is stabilized, a higher
application efficiency of the additives may be achieved. As a
result, the amount of additives that were conventionally wasted may
be reduced or even eliminated. Such an increase in application
efficiency would reduce manufacturing costs related to any wasted
additives. In addition, coupling agents can be expected to more
effectively enhance the interface between the resin and the surface
of the glass fibers when they are incorporated in the sizing
composition.
[0056] One perceived advantage of utilizing the glass fiber as a
carrier for desired additives includes an overall improvement in
the performance of the products formed from the additive-sized
glass fibers. In addition, incorporating additives into the size
composition and onto the glass fibers may aid in the dispersion of
the additives evenly or substantially evenly throughout the polymer
matrix as well as in the layer or component of the end product
(e.g., the primary structural frame) in which the glass fibers are
included. Further, the efficacy of the glass fiber in terms of its
inherent reinforcing capability may be enhanced with the inclusion
of the additives into the sizing formulation. As a result, it may
be easier to optimize the glass fiber content required to achieve a
desired level of structural performance. Preferred structural
improvements enabled by glass fiber addition include increased load
rating and flexural modulus, reduced plastic creep, and better
dimensional stability versus temperature.
[0057] After the glass fibers are formed, a sizing composition
containing additives may be applied by conventional methods such as
by application rollers or by spraying the size composition directly
onto the fibers. The additives are chosen to achieve selective or
desired properties. A suitable size composition according to at
least one exemplary embodiment of the present invention may include
one or more film forming agents (such as a polyurethane film
former, a polyester film former, a polyolefin film former, a
modified functionalized polyolefin, and/or an epoxy resin film
former), at least one lubricant, and at least one silane coupling
agent (such as an aminosilane or methacryloxy silane coupling
agent). When needed, a weak acid such as acetic acid, boric acid,
metaboric acid, succinic acid, citric acid, formic acid, phosphoric
acid, and/or polyacrylic acids may be added to the size
composition, such as, for example, to assist in the hydrolysis of
the silane coupling agent.
[0058] As discussed above, the size composition may include one or
more coupling agents. Preferably, the coupling agent is a silane
coupling agent. Besides their role of coupling the surface of the
reinforcement fibers and the plastic matrix, silanes also function
to enhance the adhesion of the polycarboxylic acid component to the
glass fibers and to reduce the level of fuzz, or broken fiber
filaments, during subsequent processing. Examples of silane
coupling agents that may be used in the present size composition
may be characterized by the functional groups amino, epoxy, vinyl,
methacryloxy, ureido, isocyanato, and azamido. In preferred
embodiments, the silane coupling agents include silanes containing
one or more nitrogen atoms that have one or more functional groups
such as amine (primary, secondary, tertiary, and quarternary),
amino, imino, amido, imido, ureido, isocyanato, or azamido.
[0059] Suitable silane coupling agents include, but are not limited
to, aminosilanes, silane esters, vinyl silanes, methacryloxy
silanes, epoxy silanes, sulfur silanes, ureido silanes, and
isocyanato silanes. Specific non-limiting examples of silane
coupling agents for use in the instant invention include
.gamma.-aminopropyltriethoxysilane (A-1100),
n-phenyl-.gamma.-aminopropyltrimethoxysilane (Y-9669),
n-trimethoxy-silyl-propyl-ethylene-diamine (A-1120),
methyl-trichlorosilane (A-154),
.gamma.-chloropropyl-trimethoxy-silane (A-143), vinyl-triacetoxy
silane (A-188), methyltrimethoxysilane (A-1630),
.gamma.-ureidopropyltrimethoxysilane (A-1524). Other examples of
suitable silane coupling agents are set forth in Table 1. All of
the silane coupling agents identified above and in Table 1 are
available commercially from GE Silicones. TABLE-US-00001 TABLE 1
Silanes Label Silane Esters Octyltriethoxysilane A-137
Methyltriethoxysilane A-162 Methyltrimethoxysilane A-163 Vinyl
Silanes Vinyltriethoxysilane A-151 Vinyltrimethoxysilane A-171
vinyl-tris-(2-methoxyethoxy) A-172 silane Methacryloxy Silanes
.gamma.-methacryloxypropyl- A-174 trimethoxysilane Epoxy Silanes
.beta.-(3,4-epoxycyclohexyl)- A-186 ethyltrimethoxysilane Sulfur
Silanes .gamma.- A-189 mercaptopropyltrimethoxysilane Amino Silanes
.gamma.-aminopropyltriethoxysilane A-1101 A-1102 aminoalkyl
silicone A-1106 .gamma.-aminopropyltrimethoxysilane A-1110
triaminofunctional silane A-1130 bis-(.gamma.- A-1170
trimethoxysilylpropyl)amine polyazamide silylated silane A-1387
Ureido Silanes .gamma.-ureidopropyltrialkoxysilane A-1160
.gamma.-ureidopropyltrimethoxysilane Y-11542 Isocyanato Silanes
.gamma.-isocyanatopropyltriethoxysilane A-1310
[0060] In addition, the size composition may include at least one
resinous film forming agent. Film formers are agents which create
improved adhesion between the glass fibers, which results in
improved strand integrity. The improved processing due to the
enhanced strand integrity, particularly with respect to material
handling and material conveyance, increases the potential viability
of utilizing a multiple application chopped strand ("MACS") product
that may be optimized for wood plastic composite applications. The
film former acts as a polymeric binding agent to provide additional
protection to the reinforcing fibers and improves processability of
the glass fibers. Any conventional film forming agent known to
those of skill in the art may be utilized in the size composition.
Suitable film formers include thermosetting and thermoplastic
polymers which promote the adhesion of sizing compositions. For
example, film formers for use in the present invention may include
polyurethane film formers, epoxy resin film formers, polyolefins,
modified polyolefins, functionalized polyolefins, and saturated or
unsaturated polyester resin film formers. Specific examples of film
formers include, but are not limited to, polyurethane dispersions
such as Neoxil 6158 (available from DSM); polyester dispersions
such as Neoxil 2106 (available from DSM), Neoxil 9540 (available
from DSM), and Neoxil PS 4759 (available from DSM); and epoxy resin
dispersions such as PE-412 (available from AOC), NX 9620 (available
from DSM), Neoxil 0151 (available from DSM), Neoxil 2762 (DSM), NX
1143 (available from DSM), AD 502 (available from AOC), Epi Rez
5520 (available from Hexion), Epi Rez 3952 (available from Hexion),
Witcobond W-290H (available from Chemtura), and Witcobond W-296
(available from Chemtura).
[0061] Polyurethane film formers are a desirable class of film
formers because they demonstrate good compatibility with polyamide
matrices and help to improve the dispersion of glass fiber bundles
in the resin melt (e.g., in an extrusion process or an injection
molding process) when forming a composite article, which causes a
reduction or elimination of defects in the final article that are
caused by poor dispersion of the reinforcement fibers (e.g., visual
defects, processing breaks, and/or low mechanical properties).
[0062] Further, the size composition may include at least one
lubricant to facilitate manufacturing. Any suitable lubricant may
be used. Non-limiting examples of lubricants suitable for use in
the size composition include water-soluble ethyleneglycol stearates
(e.g., polyethyleneglycol monostearate, butoxyethyl stearate,
polyethylene glycol monooleate, and butoxyethylstearate),
ethyleneglycol oleates, ethoxylated fatty amines, glycerine,
emulsified mineral oils, and organopolysiloxane emulsions. Other
examples of lubricants include alkyl imidazoline derivatives (e.g.,
cationic softener Conc. Flakes, which has a solids content of
approximately 90% and is available commercially from Th.
Goldschmidt AG), stearic ethanolamide, sold under the trade
designation Lubesize K-12 (AOC), and a polyethyleneimine polyamide
salt at 50% active solids commercially available from Cognis under
the trade name Emery 6760.
[0063] As discussed above, the size composition may also contain
one or more additives to achieve selective properties in the end
product. For example, the additive may be selected to make the
glass fiber more compatible with the resin matrix or to provide a
mechanical or visual property. As will be appreciated, the
additives may be included in the sizing composition in amounts
sufficient to provide an acceptable or desired range of a
particular attribute caused by that additive. Examples of additives
include, but are not limited to, fire retardants, UV stabilizers,
processing aids, antioxidents, mold inhibiting agents, lubricants,
colorants, coupling agents, sealants, friction modifiers, color
stabilizers, infrared (IR) reflectors, fire retardants, smoke
suppressors, pigments, biocides, dyes, additives to improve surface
feel and/or abrasion resistance, and additives to reduce roughness.
Because the additives are applied with the size composition
directly onto the glass fiber, the additives may be incorporated
into the size composition at a reduced or optimal level. Further,
incorporating the additives as part of the sizing composition
applied to the glass fibers permits the additives to be evenly or
substantially evenly dispersed throughout the primary structural
frame. Additionally, the inclusion of additives to the size
composition permits for the customization of product-specific
sizing compositions tailored to achieve desired physical or
structural attributes.
[0064] It is to be noted that the exclusion of coupling agents from
the size composition would be deleterious in terms of the
structural performance of the end product. As a result, it is
preferred that two coupling agents are included in the sizing
composition. The first coupling agent is chosen to make the glass
fiber compatible with the polymer resin and to enhance the
interface between the polymeric composition and the surface of the
glass fibers. The first coupling agent may be a coupling agent that
is typically present in a conventional size formulation. The
selection of the second coupling agent is made to best suit the
cellulosic or natural fibers, and, as such, is not a typical
component of a generic conventional size composition for glass
fibers. In particular, the second coupling agent is included to
enhance the interface between the first polymeric composition and
the boundary between the primary structural frame and the
longitudinal recess when the longitudinal recess contains the
cellulosic or natural fibers. One benefit of including a coupling
agent for natural fibers such wood is that it provides a way to
enhance the interface between the structural frame and the
longitudinal recess, where the wood fibers or wood flour would be
present.
[0065] Other coupling agents may be present depending on the
desired application and individual components of the composite
product. The coupling agents may be selected from the coupling
agents described above with respect to the sizing composition,
including, but not limited to, those coupling agents set forth in
Table 1. The first coupling agent may be present on the glass fiber
in an amount from about 1.5 to about 2.5% by weight of the total
composition of the structural frame and the second coupling agent
may be present on the glass fiber in an amount from about 0.5 to
about 1.0% by weight of the total composition of the structural
frame.
[0066] The balance of the size composition is composed of water. In
particular, water may be added to dilute the aqueous sizing
composition to a viscosity that is suitable for its application to
glass fibers. The size composition may be made by combining the
separate components (excluding water) in a container. Water is then
added in an amount to achieve the appropriate concentration and
control the mix of solids to achieve the appropriate or desired
concentration.
[0067] One issue relating to the use of fiber reinforcement in
compression, extrusion or injection molded materials is the
distribution of the reinforcement within the final article, or
within one or more components of a composite article, necessary to
achieve acceptable mechanical, thermal and impact performance. With
fiberglass reinforcement, the strength improvements tend to be
proportional to the glass content with a typical reinforced part
containing between about 15 to about 60% by volume in the final
part.
[0068] Those skilled in the art appreciate that in order to achieve
a generally uniform distribution of the fiberglass reinforcement,
particularly at higher loadings, it is preferred that the
fiberglass meet certain geometric and chemical criteria. These
criteria include, for example, the configuration of the fiberglass
with bundle forms being preferred for the resulting flow
properties, the glass bundle tex must be selected and maintained
within a range necessary to achieve a desired aesthetic appearance,
e.g., little or no fiber prints apparent on the surface of the
part. Bundle tex relates to the size of the fiber bundle and is
provided in units of weight divided by length, typically in
grams/kilometer. The fiberglass bundles should exhibit sufficient
cohesiveness to retain the bundle configuration during the
necessary processing, e.g., good "bundle integrity," and any size
or binder compositions incorporated with the fiberglass
reinforcement should exhibit good compatibility with the primary
matrix resin or blend of resins.
[0069] A variety of size compositions are known to those skilled in
the art, many of which include one or more silanes, for example
A-1100 aminosilane, A-174 methacryloxysilane, A-187 epoxy
functional silane and A-171 vinylsilane. The film former component
of the size composition should be one that will not result in undue
"blocking," e.g., the large scale sticking together or
agglomeration of fibers subsequent to the drying step, while at the
same time proving sufficient bundle integrity for subsequent
process steps, and exhibiting sufficient compatibility with the
resin matrix. Additional discussion of exemplary size compositions
may be found, for example, in U.S. Pat. No. 6,025,073 to Piret, the
contents of which are hereby incorporated by reference in its
entirety.
[0070] Various known combinations of urethanes and acrylics are
expected to be suitable for practicing the invention and other
combinations of unsaturated polyesters, epoxies, acrylics and
modified vinyl acetates are expected to be suitable as well. Other
additives may include lubricants, including both cationic
lubricants, such as Emery 6760 L, and nonionic lubricants, such as
PEG 400 monooleate and mono isostearate, strand stiffeners, for
example N-vinylpyrolidone, catalysts and other conventional
additives.
[0071] The fiberglass bundle tex can be controlled by splitting the
primary strand as many times as necessary on the chopping cot. The
bundle integrity may be controlled to some extent by applying the
appropriate film former(s) to the fiber using conventional
techniques and by applying enough energy, particularly in the form
of radiofrequency (RF) energy, to convert the aqueous film former
composition to dry film on the fiber surfaces that shows a reduced
blocking tendency. A combination of a polyurethane dispersion, for
example Witcobond W290H, Hydrosize U1-01 or Hydrosize U2-01, and a
urethaneacrylic alloy such as Witcobond A-100 can be used to form a
suitable size composition.
[0072] As will be appreciated by those skilled in the art,
composite articles fabricated according to the invention may also
include one or more reduced density components, particularly for
filling one or more voids defined by other components, for example
a structural component. These reduced density materials may be
prepared using a variety of methods, depending in part on the
properties desired for the final component. Such methods include,
for example, producing foams through chemical reactions and/or the
reducing the pressure under which the polymeric component is
maintained to allow one or more blowing agents incorporated in the
polymeric composition to expand and form a foam. Such methods may
be used in conjunction with one or more light weight filler
materials including, for example, exfoliated minerals and
inorganics and/or microspheres.
First Embodiment
[0073] Illustrated in FIG. 1 is an example of a manufacturing line
according to an embodiment of the invention in which various
components such as wood fibers (WF) 102a, base polymers (BP) 102b,
wet use chopped strand fiberglass (WUCS) 102c and other additives
(ADD) 102d are provided through feed lines 104 to a
blender/extruder mechanism 106a. Similar blender/extruder
mechanisms 106b and 106c may be used to prepare one or more
additional compositions for combination with the primary structure
or initial form 110a as it is extruded from die 108 or shortly
thereafter to fabricate a composite article. The other compositions
may be prepared in the blender/extruder mechanisms 106b, 106c to
form uniform mixtures having a suitable temperature and viscosity
and then extruding the mixture through one or more dies included in
apparatus 112 to form an initial form 110a. An example of a
cross-section of initial form 110a along plane A-A is illustrated
in FIG. 2A.
[0074] As suggested in FIG. 1, the components used in preparing the
various compositions may be quite different and specifically
selected to provide a desired combination of properties at a
preferred price point. For example, the second or filling
composition may include wood fibers (WF) or other fillers (FLR),
additives (ADD) and, if being provided as a foam, a blowing agent
(BA) in addition to the base polymer (BP) or polymer blend.
Similarly, the third or surface composition may or may not include
wood fibers or other reinforcing or filling agents, but will
typically include additives intended to provide a desired
combination of properties including, for example, color,
colorfastness, durability, fire retardancy and skid resistance, in
addition to a cap polymer (CP).
[0075] If desired, the initial form 110a may then be subjected to
additional heating and/or forming operations in unit 112 to modify
the initial form an produce an intermediate form 110b having a more
complex cross-sectional profile. An example of a cross-section of
an intermediate form 110b along plane B-B is illustrated in FIG.
2B. As illustrated in FIG. 1, if desired, the intermediate form
110b can also be then be subjected to additional heating and/or
forming operations in unit 114 to modify the intermediate form to
produce a final form 110c having an even more complex
cross-sectional profile incorporating, for example, notches,
fastener holes, tabs or other structures that will increase the
utility of the final product. An example of a cross-section of
final form 110c along plane C-C is illustrated in FIG. 2C.
[0076] Although as illustrated in FIGS. 2A-2C, the extrusion may be
limited to a single uniform material, the basic forms may be also
be and typically will be further modified with a filler material,
for example a foam or other less structural filler composition 116
as illustrated in FIG. 2D and/or modified to provide a more
"closed" configuration as illustrated in FIG. 2E. As illustrated in
FIG. 2F, the structural component may also be modified to form
complementary flanges 111a, 111b or other complementary projecting
and/or recessed structures that may provide alignment and/or
interlocking functions for the final product.
Second Embodiment
[0077] Illustrated in FIG. 3 is an example of a manufacturing line
according to another embodiment of the invention in which various
components such as wood fibers (WF) 202a, binders and/or polymers
(BP) 202b, fiberglass reinforcement (WUCS) 202c and other additives
(ADD) 202d are provided through feed lines 204 to a
blender/extruder mechanism 206. The various components are combined
in the blender/extruder mechanism 206 to form a uniform mixture
having a suitable temperature and viscosity and then extruding the
mixture through a die 208 to form an initial form 210a. An example
of a cross-section of initial form 210a along plane A-A is
illustrated in FIG. 4A.
[0078] If desired, the initial form 210a may then be subjected to
additional heating and/or forming operations in unit 212 to modify
the initial form an produce an intermediate form 210b having a more
complex cross-sectional profile. An example of an intermediate form
210b is illustrated in FIG. 4B. As illustrated in FIG. 3, a finish
layer, capping layer or other desired film or layer 218 may be
applied to at least a portion of the surface of the intermediate
form 210b from a supply 216. The additional layer or film 218 can
be applied as a premanufactured film or may be applied as a
secondary extrusion (not shown).
[0079] Depending on the intended use and the composition of the
primary material used to form the intermediate form 210b and the
additional layer or film 218, the composite structure of the
intermediate form and the additional layer or film can be then be
subjected to additional heating and/or forming operations in unit
214 to modify the intermediate form as detailed above and/or
increase the attachment between the primary material and the
secondary material of the additional layer to produce a composite
final form 210c. A cross-sectional example of a final form 210c is
shown in FIG. 4C illustrating the application of the layer 218 has
been added. Both FIGS. 4B and 4C reflect additional reinforcing
ribs 210d and recesses 210e that can be formed in the basis
extrusion for modifying the relative thickness and/or strength of
regions of the basic form. As illustrated in FIG. 4D, the
additional processing to which the intermediate form 210b is
subjected may include at least partially filling the intermediate
form, typically with a foam material or less expensive fill
composition 222 to produce a more solid structure.
Third Embodiment
[0080] Illustrated in FIG. 5 is an example of a manufacturing line
according to another embodiment of the invention in which various
components such as wood fibers (WF) 302a, binders and/or polymers
(BP) 302b, fiberglass (WUCS) 302c and other additives (ADD) 302d
are provided through feed lines 304 to a blender/extruder mechanism
306a. The various components are combined in the blender/extruder
mechanism 306a in different proportions to form at least two
separate and distinct compositions at suitable temperatures and
viscosities for extrusion processing. The two compositions are then
extruded through a die 308a to form an initial form 310a in which a
first composition 314 forms a primary structural frame for the
final product with a second composition 316 at least partially
filling recesses defined in the primary structural frame form. An
example of a cross-section of initial form 310a along plane A-A is
illustrated in FIG. 6A in which the first composition 314 is
extruded as a closed channel structure with the second composition
316 filling the recesses defined between the channel walls.
[0081] As illustrated in FIG. 5, this initial form 310a may be fed
into another extrusion die 308b in which a capping layer, finish
layer or decorative layer 318 of a capping composition CC is
applied to the initial form 310a from a to form the basic composite
product 310b. An example of a cross-section of initial form 310b
along plane B-B is illustrated in FIG. 6B. As suggested above in
connection with the previous embodiments, the basic composite
product 310b can also be subjected to additional processing in one
or more stations 312 where, for example, the product may be
subjected to additional machining or forming to obtain a final
cross-sectional profile or surface finish, introduce additional
structures for improved utility. In addition to mechanical
operations, the product may be subjected to, for example, one or
more processes involving the application of colorants, sealants,
friction modifiers, wear retarding layers, heat or UV curing to
obtain the desired combination of functional and decorative
features for the intended application.
[0082] Illustrated in FIGS. 6A-6E are various composite articles
according to the invention including two or more components formed
from a first structural composition 314, a second, typically less
structural composition 316 and a third surface or finish
composition 318, each of which will be formulated or compounded to
provide a distinct set of mechanical and durability properties. As
suggested in FIGS. 6A-6E, the distribution and configuration of the
various components can be varied widely to produce composite
articles having a desired combination of size, strength, appearance
and functionality.
[0083] As illustrated in FIGS. 6B and 6D, if present, the capping
layer 318 does not necessarily encompass the entire perimeter of
the structural 314 and secondary 316, 316a, 316b components or
structures. Particularly when the product will be installed with a
primary surface concealed, omitting the capping layer from the
concealed surfaces can reduce the overall cost of the product. As
also suggested by FIGS. 6A-6E, the recesses defined within the
primary structural frame of the first material 314 and filled with
a secondary material 316, 316a, 316b and/or other materials (not
shown) need not have any particular shape, uniform size, uniform
orientation or uniform spacing. It is anticipated that the
configuration of the recesses will be a function of the mechanical
properties of the first material 314 and the configuration and
intended use of the final product. These two parameters will
determine, in large part, the dimension and configuration of the
primary surface layers and the internal supporting or bracing
structures 314a necessary to achieve the intended
functionality.
[0084] To the extent that the desired result can be achieved with
something other than a solid mass of the first material, the
recesses or voids can be left empty (not shown) or filled with a
coextruded material 316 which may or may not expand or foam to some
degree after extrusion. Particularly for flooring or decking
applications, it is anticipated that filled embodiments may reduce
sound transmission and/or heat transmission while possibly
improving fastener retention and/or improving rigidity.
[0085] As illustrated in FIG. 6E, higher strength materials and/or
a less demanding application compared to that for the product
illustrated in FIG. 6D, will allow the relative volume of the
filled 316a, 316b regions to be increased relative to the main
surfaces 314 and the interconnecting struts, bars or webs 314a that
are intended to provide the primary structural function. By
utilizing distinct compositions to achieve the various functions,
utility and appearance of the final products, the exemplary
composite structures illustrated in FIGS. 6A-6E can achieve
improved performance and/or reduced cost relative to more
homogeneous constructions.
[0086] For example, by utilizing a capping or surface layer 318
that does not need to perform a predominate structural function,
the invention provides for more efficient use of expensive
additives, for example UV stabilizers, that provide no appreciable
benefit when incorporated into material(s) that form the bulk of
the product. As will be appreciated by those of ordinary skill in
the art, the same will hold true for other additives incorporated
to improve other specific properties or parameters including, for
example, abrasion resistance, fire retardancy, mold resistance,
surface feel and/or roughness, wear properties as well as color
retention. Similarly, by avoiding the need to blend the primary
material to achieve suitable appearance and surface properties, the
primary material may be modified to enhance its structural
performance including, for example, one or more of strength,
flexibility, hardness and thermal expansion.
[0087] It is anticipated that one application for which products
manufactured in accord with the invention will be especially suited
will be composite deck boards. As will be appreciated, there
remains a need for composite deck boards that exhibit improved
performance in one or more areas including, for example, one or
more of span ratings, appearance, weatherability, thermal
performance and durability. As detailed above, although a range of
configurations according to the invention may achieve one or more
of these improvements, it is anticipated that multi-component deck
flooring products corresponding to embodiments of the invention
manufactured using, for example an exemplary tri-extrusion process
as detailed above will incorporate one or more of the desired
improvements.
[0088] Conventional composite deck boards are typically
manufactured by extruding a thermoplastic resin, such as one or
more of polyethylene, polypropylene and PVC, that has been blended
with wood flour and/or fibers, lubricants, and additives in an
effort to lower production costs and/or improve the composite board
properties. In most instances, therefore, such conventional
processes produce composite boards manufactured completely from a
single composition in which any additives and fillers present in
the composition are dispersed substantially uniformly throughout
the entire thickness and width of the resulting composite board.
Accordingly, in order to obtain sufficient concentrations of UV
stabilizers or other bulk additives in those portions of the
composite board where they are actually required, the manufacturer
must add quantities of a suitable (an relatively expensive) UV
stabilizer or stabilizers that are essentially, if not totally,
wasted in the interior regions of the composite board.
[0089] Although other manufacturing processes may be utilized, as
detailed above it is anticipated that a three-component structure
manufactured utilizing at least one coextrusion process will be
particularly suitable. Depending on the various components and
proportions used to manufacture the respective materials, processes
and dyes used, it is expected that exemplary products manufactured
and/or configured in accord with the invention, the products may
include deck planking, balusters and/or capping or "capstock"
materials.
[0090] As will also be appreciated, depending on the intended
application of the product, recesses and voids formed in the
primary structural frame may be filled with a foaming or other
light weight composition to produce a composite article having a
substantially "solid" cross section. If foam is utilized as the
filling material, it will typically be produced through the use of
one or more blowing agents, for example CO.sub.2 or N.sub.2 that is
both non-toxic and non-combustible. By using such blowing agents,
or a compatible blowing agent system, the continued presence of the
blowing agent in the foam will not present additional concerns or
reduce the performance of the composite product.
[0091] The foamable or filled core composition will preferably
include one or more colorants, dyes or pigments so that if a cross
section of the composite article is exposed by, for example, sawing
a composite decking plank, the various components will cooperate to
provide a fairly uniform and "solid" appearance. This uniform
appearance will typically require at least the structural
component(s) and the filling or core components having similar
final colors in order to avoid highlighting the presence of
different materials. The capping or cover layer, however, is
relatively thin and will not tend to contribute as significantly to
the cross-sectional appearance.
[0092] With regard to texture, if a foamable mixture is used in the
core component, it may be compounded with nucleation materials
and/or expanded under conditions that will produce foams having a
relatively small cell size to avoid highlighting the presence of
different materials through distinct surface textures. Further, if
a foamed material is utilized and will not be completed enclosed,
it is preferable that the foamable composition be selected so that
a skin layer will form at the exposed surface and thereby avoid the
appearance of open cells and more closely match the texture and
appearance of the surrounding structures. Similarly, if the core
component is formed from a lightweight filled composition, the size
and coloration of the fill materials should be selected so that the
core component does not exhibit an "aggregate" appearance with
distinct discontinuous and continuous phases when viewed in
cross-section.
[0093] Because the fill or core material need not provide a
significant portion of the structural strength of the composite
articles according to embodiments of the invention, the core
material may be formulated using less expensive (and accordingly
weaker) polymeric compositions such as foams and more highly filled
materials. Similarly, because in some embodiments the fill or core
material will be exposed only when the composite article is cut,
the core material may be formulated with lower loadings (if any) of
reinforcing materials and will typically include lower
concentrations (if any) of those additives intended primarily for
improving appearance, for example, color fastness, scuff resistance
and finish texture.
[0094] In certain embodiments of composite articles according to
the invention, an increased contribution to the overall strength of
the composite article can be achieved by incorporating reinforcing
fibers, for example WUCS, into the foamable or filled composition.
Including reinforcing fibers in the core or fill component can also
improve the apparent uniformity between the reinforced structural
components and the core component when viewed in cross-section.
[0095] The capping, finishing or final layer 318 applied to the
primary structure will typically incorporate higher concentrations
of certain additives, for example UV stabilizers, wear resistors,
anti-skid materials and/or other antioxidants relative to the other
compositions incorporated in the final product. Similarly, as
suggested above material 314 used to form the primary structural
frame can be reinforced with higher levels of glass fibers that
those incorporated into the other compositions to modify one or
more mechanical performance parameters to obtain a product that
better satisfies the requirements of a particular application.
[0096] Illustrated in FIG. 7 is an example of a manufacturing line
according to another embodiment of the invention in which various
components such as wood fibers (WOOD) binders and/or polymers (BP),
capping polymer (CP), fiberglass (WUCS) and various additives (ADD)
maintained in separate reservoirs 402 are provided through feed
lines to a series of blender/extruder mechanisms 406a, 406b, 406c.
The various compositions prepared in each of the blender/extruder
mechanisms may then be coextruded through a die component 408 to
form a basic composite article. One or more of the exposed surfaces
of the basic composite article may then be subjected to additional
modification in subsequent equipment 414 through the addition of
surface additives 416 and/or mechanical modification of the surface
topography.
[0097] As illustrated in FIGS. 8A-8D, the combination of additional
materials and/or surface processing may be used to create composite
articles having a range of appearance and surface textures that
can, for example, more accurately simulate natural wood plank
surfaces, increase skid resistance and/or provide other desirable
features. As illustrated in FIG. 8A, surface additives 320 can be
introduced onto and/or into the surface or capping layer 318
supported on a structural component 314 to provide contrasting
areas including both defined spots and elongated regions. As
illustrated in FIG. 8B, the surface additives can be introduced as
deeper continuous bands that extend into (or even through) the
surface layer 318. As illustrated in FIG. 8C, the surface of the
surface layer 318 can be milled or pressed to create ridges of
material that may or may not (not shown) correspond to contrasting
surface additives 320. As illustrated in FIG. 8D, the surface
additives may be configured as a wedge-shaped strip 320a of a
translucent material whereby the imposed "grain" will be perceived
as providing a gradation of color across the band of material. The
wedge-shaped strip may be applied so that the exposed surface is
flush with the primary surface of the surface layer 318 (not shown)
or so that the thicker part of the strip protrudes from the primary
surface to provide surface texture. As will be appreciated, the
illustrations provided in FIGS. 8A-8D are not to scale and are not
exhaustive, but are intended instead to suggest the range of
surface configurations and appearances that can be achieved on
composite articles according to the invention by those skilled in
the art.
[0098] As discussed above, the capping, finishing or final layer
318 may be milled, embossed or otherwise machined or processed to
produce a textured surface to provide a more natural, distinctive
or safer surface as desired. In addition to the mechanical
processing, the capping layer 318 may be fabricated from a
composition to which one or more additives including wood, clay,
other fillers, different polymers, reinforcing fibers and/or
colorants have been added. The combination of the additives and the
surface processing may be utilized to produce composite articles
having, for example, a more natural wood appearance, e.g., by
simulating the coloring, grain and/or texture of a natural board,
or to provide an appearance that mimics other natural or
conventional construction materials, for example, stone or
aggregate. It is anticipated that capping layers that result in
composite articles more effectively and realistically simulating
natural or widely accepted construction materials would increase
their level of acceptance and use in the building and decorating
trades.
[0099] Alternatively, the combination of the additives and surface
processing may be utilized to produce composite articles having a
distinctive and decorative that does not obviously suggest any
natural surface. For example, the combination of the additives and
surface processing may be selected to duplicate the appearance of
conventional wood plastic composites so that it will tend to blend
with and/or complement existing installations and thereby be more
suitable for repair or replacement applications.
[0100] As noted above, in addition to the particular combination of
components used to form the surface coating, the coating can also
be subjected to one or more forms of mechanical processing during
and/or after formation. For example, the surface coating or capping
layer may be subjected to embossing, pressing, stamping, planing,
milling or other processing in order to add texture to the capping
layer that simulates a natural "wood grain" feel.
[0101] Embossing, for example, may be configured as a continuous
process in which the composite article exiting an extruder die is
fed through a set of pinch rollers, at least one of which includes
a raised pattern that will be imprinted on to the surface to which
the roller is applied. Pressing, for example, may comprise a batch
process in which a series of composite articles, for example
decking boards, are sequentially loaded and pressed in a textured
mold under temperature and pressure conditions suitable for
transferring the mold texture to one or more surfaces of the
boards. Planing may be configured as a batch or a continuous
process in which at least portions of the capping layer are removed
by rotating or oscillating blades. Although in conventional
woodworking, planing is a process typically utilized for smoothing
and/or leveling a board surface, in this instance it may be adapted
for selectively removing portions of the capping layer to cut a
desired texture or pattern into the processed surface. The
texturing process(es) utilized for producing a desired surface
appearance and texture in the final composite product will, to some
degree, guide the selection of appropriate capping layer
compositions and the thickness of the capping layer, particularly
if the process involves removing a portion of the capping
layer.
[0102] Conventional foamed boards tend to exhibit inferior
mechanical properties than solid boards of similar dimensions. Some
attempts have been made to improve the mechanical properties of
foamed boards by incorporating glass fibers, but such attempts have
not produced compositions in which the glass fibers are both
present in sufficient quantities and exhibit sufficient adhesion to
the polymeric resin(s) to achieve the desired improvement in the
mechanical properties. As noted above, composite articles according
to an embodiment of the invention utilize WUCS treated with an
appropriate size composition in the foamed core to improve
mechanical properties. Because WUCS production does not require the
drying and/or curing steps utilized in the production of
conventional fiber reinforcements, WUCS may provide both economic
and performance advantages over conventional fibers in the
production of both foamed articles and composite articles
incorporating foamed components.
[0103] Further, with regard to the composite articles fabricated
according to the various embodiments of the invention, it is
anticipated that the coextrusion process will tend to reduce
undesirable interactions between components that may be separated
in two or more compositions that will, in turn, be utilized to form
a final composite structure. For example, one problem often
associated with the use of additives in wood/plastic composite
materials is the absorption of the additives by the wood flour,
thereby lowering the effectiveness of a particular concentration of
the additive(s). Thus, by separating at least certain of the
additives into components that do not include wood flour, or have a
reduced wood flour component, it is expected that improvements will
be noted in the effectiveness of a given additive package in such a
component. This, in turn, will allow the quantity of the additives
to be reduced and/or increase the effectiveness of a defined
additive package intended, for example, to increase resistance to
UV degradation.
[0104] It is also anticipated that the multi-extrusion process
detailed above will provide certain advantages in attempting to
improve both material usage and turn costs. For example, the
composition used for forming the primary structural frame could
incorporate higher concentrations of reinforcing fibers, for
example, WUCS, for improving mechanical properties while allowing
the capping and core layers to remain relatively free of
reinforcing fibers. These improvements in material strength can be
leveraged to reduce the quantity of material necessary to obtain a
target strength and/or rigidity, typically by utilizing a more
complex cross-section, as illustrated in, for example, FIG. 6D,
whereby the structural component(s) occupy only a small percentage
of the total cross-sectional area. Accordingly, limiting the volume
of material into which the reinforcing fiber must be incorporated
can significantly reduce the contribution of the reinforcement to
the overall cost of the final product.
[0105] Again, as noted above, the primary structural frame will
typically define a plurality of recesses, channels or cavities that
may, in turn, be filled using one or more less expensive materials
that will tend to exhibit correspondingly less robust mechanical
properties. Although, as noted above, the spaces defined by the
primary structural frame may be left unfilled, it is anticipated
that most private individuals and contractors reviewing their
options in terms of composite decking materials will have at least
some preference for those articles, whether solid or composite,
that exhibit a sufficiently "solid" appearance. Accordingly, the
use of one or more filling materials including, for example, foamed
polymer(s), polymer/wood compositions with higher wood flour
concentrations and/or combinations of two or more compositions to
fill any significant voids in the structural component will be
preferred.
[0106] Although, as detailed above composite boards according to
the invention are anticipated to be particularly useful in exterior
decking applications and may be provided in a range of
configurations such as planks, balusters and capping trim in a
variety of lengths, widths and thicknesses. The improved
durability, dimensional uniformity and appearance may also allow
for other applications including, for example, window and door
framing. Indeed, depending on the particular materials,
configuration and application, composite articles according to the
invention may be approved for structural applications, such as some
framing, particularly in non-load bearing applications.
[0107] Although exemplary, non-limiting embodiments of the
invention have been described in detail hereinabove, it should be
understood that many variations and/or modifications of the basic
inventive concepts herein taught, which may appear to those skilled
in the art, may still fall within the spirit and scope of the
example embodiments of the invention as defined in the appended
claims.
Fourth Embodiment
[0108] A fourth embodiment according to the invention may be
prepared without incorporating any wood particles in any of the
polymeric components that make up the composite article. For
example, in a composite article incorporating a capstock, the
polymeric material from which the capstock is fabricated will
typically be a filled and additive-modified polymer that includes
one or more additives that would be expected to provide improved
wear and color fastness characteristics. The second or intermediate
section would typically be a glass fiber-reinforced polymeric
material having sufficient strength and stiffness and a
configuration that will allow this section or component to serve as
the structural skeleton, i.e., of the composite article. The third
element, which may also be referred to as a core or filler element,
will typically include one or more reduced density materials,
particularly one or more foamed polymeric materials or light weight
fill material. By avoiding the use of wood fibers or flour, the
resulting composite according to the fourth embodiment will tend to
exhibit improvements in those parameters affected by the nature and
characteristics of the wood products and/or byproducts relative to
corresponding composite articles that do incorporate wood or other
organic fiber material.
[0109] By avoiding the use of wood or other organic materials, the
resulting composite article will tend to exhibit improved
resistance to certain problems associated with organic materials
including, for example, mold, mildew, bacteria or insects, without
the need for similar quantities of biocides or other preventative
treatments. It is also anticipated that the elimination or
reduction of wood products, particularly in the capstock or surface
layer would have benefits in respect any related manufacturing
processes. In particular, the capacity of equipment necessary for
storing, conditioning, processing, transporting and/or
incorporating wood or other organic materials into the polymeric
compositions may be significantly reduced. Reductions in the number
and/or capacity of such equipment will tend to reduce costs and
avoid potential hazards associated with the dust generated by
and/or solvents used for processing the wood or other organic
materials.
[0110] Further, although it is anticipated that in most instances
the structural component formed from the first polymeric
composition and/or the surface or finish layer will form the
exterior of the composite article, in some instances the second
polymeric composition may form the bulk of the article. As
illustrated in FIG. 9A, the basic construction according to this
embodiment is an extruded slab of a polymeric foam composition 316.
Using the coextrusion processes and apparatus detailed above,
additional components may be incorporated with and/or applied to
the basic polymeric foam composition to improve selected properties
including, for example, appearance and strength.
[0111] As illustrated in FIGS. 9B-E, a full or partial finish layer
318 and a one or more reinforcing elements 314 can be incorporated
into the primary foam composition. As will be appreciated by those
skilled in the art the relative quantity and configuration of the
reinforcing component 314 can be used to increase horizontal and/or
vertical strength and may be incorporated as relatively simple,
FIGS. 9D and 9E, or complex, FIGS. 9B and 9C, shapes.
Fifth Embodiment
[0112] A fifth embodiment of a composite article according to the
invention provides improved fire retarding performance. Although
the basic product configuration may be similar to that described
above in connection with the fourth embodiment (no wood flour,
fiber, or particles present), the fifth embodiment will utilize a
capstock composition that includes higher filling levels and/or
concentrations of one or more fire and flame retardant and/or smoke
suppressing materials including, for example, various organic
halogen compounds, phosphorus compounds, antimony trioxide, alumina
trihydrate, magnesium hydroxide, zinc borate, metal chelates
incorporating Fe, Co, Ni, Cu, or Zn (particularly in combination
with Al(OH).sub.3 and Mg(OH).sub.2), and various intumescent
compounds.
[0113] By incorporating higher levels of these fire and flame
retardants and/or suppressants, for example, magnesium hydroxide
(MgOH.sub.2), in the capstock layer, in combination with the
internal structural component(s), particularly those that are
reinforced with higher levels of glass fibers, a composite article
may be fabricated that exhibits improved resistance to burn through
and/or sagging in the event of a fire. In such a composite article,
the capstock layer acts as an ablative or energy absorbing layer
while the reinforced structural component or substrate supports the
capstock and provides an improved physical barrier. Composite
articles fabricated according to this embodiment are expected to
have particular utility in fire-rated building products.
Sixth Embodiment
[0114] A sixth embodiment of a composite article according to the
invention can provide an improved and/or more natural surface
appearance. In this embodiment, during fabrication of the composite
article a combination of polymers, which may be provided in one or
more forms including fiber, flake, particle and pellet, are
introduced into the capstock layer or the surface layer. Depending
on the composition, form, the apparatus used to achieve the
incorporation or addition and the various additives such as fillers
and colorants incorporated in the polymer(s) being added, a range
of surface effects can be produced. For example, adding polymer(s)
having a darker color than the base polymer composition can produce
variegated surface finishes that can more realistically mimic the
grain of natural wood products.
[0115] Similarly, incorporating polymers having various colors
and/or fillers can be used to create a wide range of distinct and
highly customizable finishes that may or may not mimic natural
materials. This ability to provide different finishes and looks
through this technique may increase the use of these materials by
designers and stylists in the manner in which other existing
synthetic materials such as CORIAN.RTM. and/or synthetic stone
products such as SILESTONE.RTM. are specified and employed.
Accordingly, composite articles according to this embodiment of the
invention may be acceptable for uses and applications ranging from
exterior decking to interior and exterior finishing systems.
Seventh Embodiment
[0116] A seventh embodiment of a composite article according to the
invention can utilize a more substantial foamed component while
still providing an improved and/or more natural surface appearance.
In this embodiment, the majority of the composite article comprises
a polymeric foam that may incorporate minor internal structural
components and/or a capping or finish layer intended to provide
improved appearance and/or durability. In lieu of the capping or
finish layer, as the polymeric foam is extruded a combination of
polymers, which may be provided in one or more forms including
fiber, flake, particle and pellet, may be introduced into an outer
portion of the foam. Depending on the composition, form, the
apparatus used to achieve the incorporation or addition and the
various additives such as fillers and colorants incorporated in the
polymer(s) being added, a range of surface effects can be produced.
For example, adding streaks or stripes of polymer composition(s)
having a darker color than the base polymer composition can produce
variegated surface finishes that can more realistically mimic the
grain of natural wood products.
[0117] Further, as noted above, in addition to the particular
combination of materials introduced into the outer layer of the
foam, the foam and/or any incorporated materials can also be
subjected to one or more forms of mechanical processing during
and/or after formation. For example, the surface coating or capping
layer may be subjected to embossing, pressing, stamping, planing,
milling or other processing in order to add texture to the capping
layer that simulates a natural "wood grain" feel as suggested in
FIG. 8C.
Eighth Embodiment
[0118] An eighth embodiment of a composite article according to the
invention provides improved resistance to biological degradation in
function or appearance. Although the basic product configuration
may be similar to that described above in connection with the
previous embodiments, the eighth embodiment will incorporate one or
more compositions, particularly those that are or may become
exposed to the environment, that include higher filling levels
and/or concentrations of one or more biocidal agents or biocides.
Typically the selected biocides will be those having demonstrated
efficacy against organisms that would tend to decompose the wood
and/or polymeric components of the composite article or simply
those organisms that will tend to blemish or degrade the appearance
of the affected surfaces in some manner, e.g., mildew or black
algae forming on wetted surfaces.
[0119] The biocides may be introduced as liquids or particles
including, for example, relatively insoluble polymeric
nanoparticles which can be introduced into the compositions as
suspensions, emulsions or dry powders. Those biocides distributed
or otherwise introduced into one or more of the compositions may
also act as a diluent to improve the volumetric distribution of the
biocide(s) as the small particle or nanoparticles containing the
biocide(s) and/or other additives, throughout the composite.
Providing a plurality of biocides on separate insoluble
nanoparticles can more effectively maintain separation between the
active compounds and, in appropriate instances, can improve the
stability of the biocide(s) and prolong their biocidal
effectiveness by reducing mutual negative interactions between the
biocide(s) and/or other components.
[0120] The biocides may be selected in consideration of their
compatibility with the primary polymeric component(s), the polymers
used in forming the nanoparticles (if any), the compatibility of
the biocides, the solubility characteristics of the biocide(s) in
the composition, other characteristics of the biocide including,
for example, porosity, release rate, and toxicity; and
complications (if any) that the use of such a biocide or
combination of biocides would introduce into the manufacture of the
composite articles. If nanoparticles are utilized, as a general
rule the more highly branched polymers will tend to be more useful
in forming less dense and more porous polymers that will, in turn,
exhibit higher biocide release rates than particles forms form
predominately linear polymers. Accordingly, polymers that are
particularly useful for forming nanoparticles for distributing
biocides throughout a WPC include, but are not limited to,
polyvinylpyridine, polymethacrylate, polystyrene,
polyvinylpyridine/styrene copolymers, polyesters, polyethylene,
polypropylene, polyvinylchloride and blends thereof. Further, each
of these homopolymers may be blended with acrylic acid or other
suitable compound.
[0121] The biocide(s) may also be selected according to the target
organism(s) to which exposure would be reasonably expected in the
intended application of the composite article, stability at the
temperature ranges and pH ranges anticipated during manufacture
and/or use. As used herein, the term "biocide" is intended to
encompass any compound or substance that tends to kill or inhibit
the growth of one or more microorganisms and/or invertebrates,
including, for example, molds, slime molds, fungi, bacteria,
insects and arachnids. Accordingly, insecticides, fungicides and
bactericides are each an example of a biocide. More specific
classes of biocides include, but are not limited to, chlorinated
hydrocarbons, organometallics, halogen-releasing compounds,
metallic salts, organic sulfur compounds, compounds and phenolics.
More specific examples of biocidal compounds include, without
limitation, copper naphthenate, copper oxide, zinc naphthenate,
quaternary ammonium salts, pentachlorophenol, tebuconazole (TEB),
chlorothalonil (CTL), chlorpyrifos, isothiazolones, propiconazole,
other triazoles, pyrethroids, and other insecticides, imidichloprid
and oxine copper. Additional inorganic preservatives and biocides
include, for example, boric acid, sodium borate salts, zinc borate,
copper salts, zinc salts and combinations and mixtures thereof.
[0122] As will be appreciated by those skilled in the art, the
polymeric nanoparticle technique may be used for distributing
additives other than biocides. In particular, certain flame
retardants and/or smoke suppressants may be introduced into one or
more of the compositions used to form the composite articles by
incorporating the active ingredient into a suitably porous
nanoparticle. For example, fire retarding chemicals, water
repellants, colorants, UV inhibitors and adhesive catalysts can be
incorporated into such particles. As will be appreciated, the
nature of the additive and the primary polymeric component(s) of
the WPC will determine which polymers are most suitable for the
incorporation and distribution of such additives. For example,
flame suppressing compounds such as borax/boric acid, guanylurea
phosphate-boric acid, dicyandiamide phosphoric acid formaldehyde
and diethyl-N,N-bis(2-hydroxyethyl)aminomethyl phosphate may be
incorporated into nanoparticles formed from polyvinylpyridine or
polyvinylchloride.
Testing
[0123] The impact of the addition of WUCS material in WPC articles
was examined in a series of sample articles. In a first trial,
various quantities of WUCS (1/4 inch (6.4 mm) chop, 16 .mu.m fiber,
E-glass having a nominal 10% moisture content) or DUCS as
reinforcing fibers ("RF") were combined with wood flour ("WF"),
(fresh 40 mesh pine) and a polymer, either polypropylene (PP)
having a melt flow index ("MFI") of about 5 or HDPE, to produce
various compositions that were formed into plank boards. Ten
samples where then cut from each of the plank boards for testing.
Additional samples were prepared using 1-2% of a coupling agent
selected from POLYBOND.RTM. 3029 (maleated HDPE) (available from
Crompton) and FUSABOND.RTM. 100D (maleated LLPE) (available from
DuPont). The samples cut from the plank boards formed from the
various compositions were then tested according to ASTM 709 to
example their relative flexural properties. The sample compositions
prepared in the first trial were compounded according to TABLE 2.
TABLE-US-00002 TABLE 2 TRIAL 1 Polypropylene Sample WUCS
Composition PP:WF:WUCS WUCS (Chop Length) Number (Dry Weight)
(Moisture %) (in/mm) 1 50:50:0 na na 2 50:40:10 .apprxeq.10
0.25/6.4 3 40:40:20 .apprxeq.10 0.25/6.4 4 50:40:10 .apprxeq.15
0.25/6.4 5 80:0:20 .apprxeq.10 0.25/6.4 6 50:40:10 .apprxeq.10
0.125/3.2 7 50:50:0 na na
[0124] The sample compositions prepared in the second trial were
compounded according to TABLE 3. TABLE-US-00003 TABLE 3 TRIAL 2
HDPE Sample Coupling Composition HDPE:WF:RF Coupling Agent Number
(Dry Weight) Agent Quantity 1 50:50:0.sup.1 na na 2 40:50:10.sup.1
3029 1 3 40:40:20.sup.1 3029 1 4 40:30:30.sup.1 3029 1 5
34:40:20.sup.2 3029 1 6 34:40:20.sup.2 3029 2 7 40:40:20.sup.1 100D
1 8 50:50:0 na na .sup.1WUCS - 1/4 inch chop, 10% moisture
.sup.2DUCS - 1/4 inch chop, dry and 4% lubricant
[0125] The data generated from the samples showed that relative to
the control samples (those with no added WUCS or DUCS), the
addition of 20% and 30% WUCS resulted in 34% and 45% percent
increases in the Young's Modulus of the samples. Similarly, the
combination of 20% DUCS and at least 1% coupling agent in the HDPE
samples achieved as much as a 75% increase in the Young's Modulus
when compared with the control samples. It is expected that
additional development of the size composition provided on the WUCS
and/or the use of coupling agents would tend to reduce the
difference in the Young's Modulus between the WUCS and DUCS
compositions.
[0126] Although the invention has been described in the context of
particular composite articles and component materials, those
skilled in the art will appreciate that the inventive methods and
structures may be adapted for a wider range of polymeric
compositions, additives, structures and applications. Example
embodiments of the invention have been disclosed herein and,
although specific terms are employed, they are used and are to be
interpreted in a generic and descriptive sense only and not as
limiting the invention to the embodiments disclosed. Accordingly,
it will be understood by those skilled in the art that various
changes in form and details of the disclosed compositions, articles
and methods may be made without departing from the spirit and scope
of the invention as set forth in the following claims. In
particular, those skilled in the art will appreciate that various
compositions and structures described with respect to one
embodiment may be combined with complementary compositions and
structures described with respect to a different embodiment to form
a new composite article in accord with the disclosed invention.
* * * * *