Note: Descriptions are shown in the official language in which they were submitted.
8558-001 - _
Sandabla and Stsia,~le Plastic\Kood Composite
8ackgromd of the Iavpatioa
1. Field of ;nveatioa
'this invention relates to the art of composites
comprising of plastic and a mixture of plastic and natural
fibers and methods for producing the same, and more
particularly to window an<i door components made of a the same
composite.
2. Description of R~alated ,Art
It is known in the art to combine different fozms of
plastic with different fozms of natural fiber such as
woodflour, crushed shells of nuts, and other natural
matezials. The purpose for such previous combinations has
been to enhance the physical properties and lowed the cost of
the prodact.
In the art of window and door components and trim, such
components have historically been made of 100E natural wood.
Ia recent years, components of windows and doors have been
made of plastic for certain performance and cost advantages.
In such cases, the plastic is often colored with a coloring
agent to give a wood-like appearance oz to match the colors
of the surrounding area. Although the colored plastic may
appear somewhat wood-like, it can :tot be painted or snnded or
2
stained like real wood. lror this reason, it was difficult,
if not impossible, to match plastic components to natural
wood surroundings. Anoth~.°.r product is to wrap the plastic
with a foil or laminate having a wood-like appearance. Such
foil laminates ara expensive and easily damaged.
the present invention contemplates a new and improved
article and method of making the article which is effective
in use and ovezcomes the :Eoregoinq difficulties and
disadvantages while providing better and more advantageous
overall results.
5~~. of the Inveatioa
is accordance with the preseat invention, a new and
improved article of manufacture and method of making the same
is provided.
More pazticularly, in accordance with the invention, the
composite article includes first and second zones. The first
zone is comprised of plastic and the second zone is comprised
of plastic and natural fiber. The first and second zones
being integral, being coextruded together. The ratio of
natural fiber to plastic in the second zone is between 10% to
55%.
In accozdance with another aspect of the invention, the
second cone is outward of the first zone and includes an
outer surface. The outer surface has sufficient porosity so
as to hold and retain wood stain so that the article is
stainable. The outer surface is also sandable and can be
embossed to resemble wood grain.
Accord3.ng to another aspect of the invention, a weather
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stripping member can be ai:~ixed to the outer surface of the
seeoad zone by a continuous coextrusioa process_
According to another aspect of the invention, the
article is a column with a generally square cross-section. A
center plane divides the ~'irst zone from the second zone,
with the second zone to be positioned as the interior side of
an associated window.
According to another aspect of the invention, the
article includes color adjusting means for adjusting
discolorations in the natural fiber and coloring means for
coloring the article to resemble the wood to be emulated. Ia
one embodiment, the adjusiang means is titanium dioxide.
According to a further aspect of the invention, a method
of manufacturing a composite article including a first zone
of plastic and a second zone of plastic and natural fiber
includes the steps of simultaneously extruding a first
extrudate from a first exl:ruder and a second extrudate from a
second extruder through a dual extrusion head, thereby
forming an integral composite of the first and second
extrudate. It is important to extract the moisture is the
wood (approximately 5% to 6E), this is done by pulling a
vacuum of at least D.S ba:r in the vent section of the
composite extruder. Next, the composite is passed through a
vacuum calibration system to ~orm the article with the means
of a puller. Next, the article is cut to a desired length
with a cutter. A coloring agent and a color adjusting agent
can be added to the process. Other steps may include mixing
a ratio of between 10% and SS% natural fiber and between 90%
and 4S% polyvinylchloride in a ribbon blender until
homogenous. The mixing of the ratio of natural fiber and
polyvinylchloride can also be blended at the throat of the
second extruder.
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One advantage of the present invention is the provision
of as article which can better withstand temperature
variation. Because natural fibers such as woodflour and
other materials containing cellulose have better dimensional
stability in cases of temperature variation than does
plastic, the article tends to retain dimensional stability of
a wider range of temperatures.
Another advantage of the invention is the provision that
the material may be inexpensively made of plastic and yet can
have an outer surface which can be sanded, stained, or
painted as if made of solid wood.
A still further advantage of the invention is the
provision that the material can be colored to more closely
resemble surrounding natv.ral wood, and can be further sanded
or stained or painted to more fully resemble the surrounding
natural wood.
Still other benefits. and advantages of the invention
will become apparent to those skilled in the art to which it
pertains upon a reading amd understanding of the following
detailed specification.
srief Dascs~ivtion of the Drawiac~s
The invention map take physical form in certain parts
and arrangements of part;;, a preferred embodiment of which
will be described in detail in this specification and
illustrated in the accompanying drawings which form a part
hereof and wherein:
FIGURE 1 is a perspective view of a piece of trim
manufactured according to the invention;
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f iGURE 2 is a perspective view of another component, is
this oase a handle rail, nusnufactured according to the
invention;
5 FIGURE 3 is perspect5.ve view of a double hung window
utilizing Components manui:actured according to the invention;
FIGURE 4 is a steel, fiberglass or wood door utilizing
campoaents manufactured a<:cording to the invention;
FIGURE 5 is a window component manufactured according to
the invention; and,
FIGURE 6 is a schematic diagram of equipment utilized to
manufacture the invention.
De~criptioa of the Preferred Smbo~meat
Referring now to the drawings wherein the showings are
for purposes of illustrating a preferred embodiment of the
invention only and not fo;r purposes of limiting the same,
FIGURES 1-5 show various composite articles of
manufacture according to the invention. More specifically,
with reference to FIGURE 1, the composite article 1D has a
first zone 12 and a second zone 14. The second zone 14 has
an outer surface 16. In a preferred embodiment, the first
zone 12 is made of entirely of plastic_
The preferred plastic is polyvinylchloride, or PVC. The
second zone 14 is a composite made of natural fiber and
plastic. The preferred plastic is polyvinylchloride. The
preferred natural fiber 9.s eroodflour, although other natural
fibers containing naturally occurring cellulose such as
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crushed shells of nuts can be successfully used.
The ratio of natural fiber to plastic in the second zone
14 is preferably between :l0% and 55% natural fiber compared
9 with 90% to 45% plastic.
The outer surface 16 of the second zone 14 is formed so
that it has sufficient porosity ao as to hold and retain
conventional wood stain. The porosity of the outer surface
20 16 is controlled by adding a small additional amount of metal
release agent. Increasing the amount of the metal release
agent decreases the porosity of the outer surface 16 and
decreasing the amount of 'the release agent increases the
amount of porosity_ The preferred metal release agent is
15 available under commercial name Rheochem Rheolube. The outer
surface 16 is also sandable as with conventional sandpaper.
The outer surface 16 can also be painted. As such, the outer
surface 16 of the second zone 14 can be sanded, painted or
stained to closely resemble genuine wood arork and can be
20 matched to other work in the room application.
In ozder to more accurately emulate the surrounding wood
work, a commercially available coloring agent can be added to
the plastic to more closely resemble the color of Wood to be
25 emulated. In the second zone 14, variations and color of
natural fiber may make such color emulation difficult to
accomplish. It has been learned that better. color uniformity
can be obtained by applying a color adjusting agent, such as
titanium dioxide, to the natural fiber/polyvinylchloride
30 composite along wlth the coloring agent. The color adjusting
agent smooths out color variations in the natural fiber and
allows. them to be more uniformly tinted by the coloring
agent.
35 The composite which makes up the secoild zone 14 includes
natural fiber and a ratio of between 10% and 55$,
polyvinylchloride at a ratio of between 90% and 45%, and an
external lubricant to ohta~i.n a surface suitable for staining.
A preferred lubricant is available under the trade name
Rheochem Rheolube. In addition, a small amount of a fusion
enhancer is required to promote fusion in the extruder prior
to venting to allow application of a vacuum to abstract
moisture from the natural fiber.
With reference to FIC;uRE 6, a typical manufacturing
operation is schematically shown. A first extruder 20
extrudes plastic through a dual extrusion head 26. A second
extruder 22 excludes the natural fiber/plastic composite
through the dual extrusion head 22. The preferred
manufacturing operation utilizes a conical twin extzuder
because is has good polyv:inylchloride processing
characteristics and can homogenize the polyvinyl chloride and
woodflour. Single extruders can be successfully used
although the throughput rates will be considerably less.
From the dual extrusion head 26 exists an integral composite
article IO in which the first zone and second zone are
integrally connected. The composite article 10 is next
passed through a vacuum calibration device 30 in order to
form the extrudate. According to a currently preferred
embodivnent, the article is embossed through an embossing
device 32 with reference to FIGURE 2, common designs Which
are embossed onto the outer surface 16 of composite articles
10 include wood grain 36. With reference to FTGURES 6, a
pulley 40 continues to pull the composite article 10 through
the manufacturing device. Finally, a cutter 42 cuts the
composite articles 10 to the desired length.
A typical polyvinylchloride formulation that can be
mixed with woodflour follows using commercially available
products follows:
CA 02144566 1997-07-22
.
100 lbe of Georgia Gulf 3301 w~iT 194 (typical indoor
powder configuration of polyvinylchloride)
2,155 lbs of Rheocheia Rheolube 185
0.259 lbs o~ 1111ied Signal AC316 (fusion aahanaer~
1.393 lbs of Ferro H-9156 Pigment
4.310 lbs of DuPont'R960 (titanium dioxide)
The above ingredients can be added by the ~aaaufaeturer
of the polyviaylchloride (in this case, Georgia Gulf) when
the plastic is manufactured. Ia the alte~ative) the
ingrodieats caa'be added later is a high intensity mixer.
This compound is then IQlYed in a Ribbon blender with the
natural fiber and mixed or metered at the extruder throat.
The preferred natural fiber, woodflour, is manufactured in
hardwood and pine grades, or in auy natural fiber containing
cellulose, and ~:n various particle size distributions. while
mesh sizes from_~ 2'0 mesh ~ 850 microns ) to 1~0 ~aesh ( 106
microns) are acceptable, the.prezerred wood fiber is
available from American Wood Fibers and is 80 mesh (180
micron) hardwood grade.
With reference to FTGURE 2, a handle rail 46 such as
might be manufactured in this process is shown.
With reference to FIGURE 3, typical double hung windows
48 are shown. Certain components of double hung windows 48
can be advantageously manufaetuxed through the inventive
process disclosed herein. Due to temperature variations in
windows, with very cold weather oa one side of the window
3o bezng juxtaposed against warm temperatures on the interior
side of the window, dimensional integrity of plastic window
components can be a problem. Since natural fibers have
better thermal stability than some plastics, the addition of
natural fiber can improve pexformxnce. .Heretofore, plastic
components world necessarily be visible from the interior
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side of the window. These interior components could only
roughly approximate the appearance of natural wood. Some
previous attempts to rectify this problem included wrapping
such components with ~oil which simulated wood grain. As
discussed previously, this technique was expensive and the
foil was often too fragile to retain its appearance for long
periods of time under heavy use. With reference again to
FIGUxE 3, the interior half 52 of a typical doable hung
window 48 is shown schematically as including the natural
fiber/polyvinylchloride composite. With reference to FIGUxEs
3 and 5, it can be seen that the interior half 52 of the
component includes the natural fiber/natnral composite while
the exterior 56 is made entirely of polyviriylchloride.
25 With continuing reference to FIGURE 5, according to one
embodiment of the invention, weather stripping 60 is
integrally affixed to the outer surface 16 of the second none
14 along a longitudinal e~dqe 64.
With reference to BI~GURE 4, another common application
of the invention is shown. In FIGORE 4, a door 66 is
primarily made of metal, fiberglass or wood. Some designs
feature window glass 68 surrounded by trim 70. The trim 70
is also a good applicatio:u of the composite article 10 of the
invention.
The invention has bean described with reference to a
preferred embodiment. Obviously, modifications and
alterations will occur to others upon a reading and
understanding of this specification. It is intended to
include all such modifications arid alterations insofar as
they come within fhe scope. of the appended claims or the
equivalence thereof.
