U.S. patent application number 10/365870 was filed with the patent office on 2003-08-21 for hollow profile decking system comprising plank and anchor using anchor flange construction.
This patent application is currently assigned to Andersen Corporation. Invention is credited to Bruchu, Todd, Dalquist, Kurt, Evans, Harold H., Galowitz, Dennis A., Garofalo, Robert F., Heikkila, Kurt E., Puppin, Giuseppe, Worm, Thomas B..
Application Number | 20030154662 10/365870 |
Document ID | / |
Family ID | 27734970 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030154662 |
Kind Code |
A1 |
Bruchu, Todd ; et
al. |
August 21, 2003 |
Hollow profile decking system comprising plank and anchor using
anchor flange construction
Abstract
A decking system, decking components and an installed deck for
use on a support structure. The decking system comprises hollow
profile planking units having anchor flanges on opposite edges that
cooperate with an anchor structure to form a deck or platform. The
flanges and the anchor units are shaped and configured to closely
interact and form an installed platform structure. The planks
comprise an extruded thermoplastic wood fiber composite having an
internal structure sufficient to withstand installation,
engineering forces placed on the installed platform, weathering and
use. The anchor structures have a shape that conforms to the anchor
flanges on the decking profiles to hold the deck in place.
Inventors: |
Bruchu, Todd; (Lake Elmo,
MN) ; Dalquist, Kurt; (North Branch, MN) ;
Puppin, Giuseppe; (Bayport, MN) ; Worm, Thomas
B.; (Brooklyn Park, MN) ; Garofalo, Robert F.;
(Stillwater, MN) ; Evans, Harold H.; (Hudson,
WI) ; Heikkila, Kurt E.; (Marine on St. Croix,
MN) ; Galowitz, Dennis A.; (Stillwater, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Andersen Corporation
Bayport
MN
|
Family ID: |
27734970 |
Appl. No.: |
10/365870 |
Filed: |
February 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10365870 |
Feb 13, 2003 |
|
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|
09702005 |
Oct 30, 2000 |
|
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Current U.S.
Class: |
52/87 |
Current CPC
Class: |
E04F 2203/04 20130101;
E04F 2015/02094 20130101; E04F 15/10 20130101; E04F 19/06 20130101;
E04F 15/02194 20130101; E04F 15/02172 20130101 |
Class at
Publication: |
52/87 |
International
Class: |
E04B 001/32 |
Claims
We claim:
1) A system for the installation of a decking structure on a
support, the system comprising: (a) one or more hollow profile deck
members, the members free from an installation slot, each member
comprising a tread surface, a parallel opposite support surface and
an anchor flange on opposite edges of the member; and (b) one or
more anchors that can cooperate with the profile flange in the
installation of the profile on the support, the anchor comprising
means to attach the anchor to the support using an anchor base
portion, the anchor further comprising a vertical member extending
from the base portion ending in a transverse portion, the
transverse portion extending from the vertical portion forming an
anchor flange that can interact with the profile flange in
installing the member on the support.
2) The system of claim 1 wherein the profile deck member comprises
a hollow profile comprising a thermoplastic polymer-biofiber
composite material.
3) The system of claim 2 wherein the hollow profile comprises
vertical support webs extending between the support surface and the
tread surface, the webs horizontally spaced at a distance of about
2 centimeters or more between vertical support web structures.
4) The system of claim 3 wherein adjacent support webs form an arch
support structure within the hollow profile positioned such that
the arch is compressed by a force normal to the tread surface of
the plank.
5) The system of claim 4 wherein the hollow profile contains two or
more arch like supports within the profile.
6) The system of claim 1 wherein the arch like support structure
within the profile also forms a void space defined by the tread
surface and the upper surface of the arch surface.
7) The system of claim 6 wherein the profile also comprises a void
space defined by the support surface and the bottom surface of the
arch structure.
8) The system of claim 1 wherein the anchor comprises a base, a
vertical member extending from the base and a transverse member
extending from the vertical member, the vertical member having an
aperture for an attachment hardware, the aperture extending through
the vertical member.
9) The system of claim 8 wherein the anchor member comprises an
extruded metallic unit having a length of greater than 2
centimeters with the base portion extending along the length of the
extruded anchor and the anchor flange extending along the length of
the extrusion.
10) The system of claim 8 wherein the anchor member comprises an
extruded thermoplastic unit having a length of greater than 2
centimeters with the base portion extending along the length of the
extruded anchor and the anchor flange extending along the length of
the extrusion.
11) The system of claim 8 wherein the anchor has at least one
integral screw fastener.
12) The system of claim 8 wherein the anchor flange extends from
the vertical portion of the anchor but departs from the horizontal
by an angle of greater than about 5.degree. to form an area that
contacts a complementary area in the anchor flange of the deck
member.
13) A plank, for deck or platform installation, comprising an
extruded thermoplastic-biofiber hollow profile, the plank
comprising a linear member having a tread surface and a parallel
opposite support surface and parallel opposite edges, each edge
comprising an anchor flange, said member comprising at least one
internal arch support structure, wherein the plank has a
compressive strength of at least 1500 pounds per square inch (10
megapascals) and a coefficient of thermal expansion of less than
about 1.5.times.10.sup.-5 inch per inch .degree. F.
14) The plank of claim 13 wherein the anchor flanges are proximate
the support surfaces.
15) The plank of claim 13 wherein the thermoplastic comprises a
polyolefin.
16) The plank of claim 13 wherein the thermoplastic comprises a
polyvinyl chloride.
17) The plank of claim 13 wherein the biofiber comprises wood
fiber.
18) The plank of claim 13 wherein the plank comprises three or more
arch support structures formed within said linear member.
19) The plank of claim 13 wherein the anchor flange extends from
the plank at an angle that departs from the horizontal by at least
5.degree..
20) The plank of claim 13 wherein the plank has a width of at least
3 inches.
21) The plank of claim 13 wherein the width of the plank is about 3
to about 18 inches.
22) The plank of claim 13 further comprising a capstock layer.
23) The plank of claim 22 wherein said capstock comprises an
abrasion resistant coating.
24) The plank of claim 23 wherein said abrasion resistant coating
comprises acrylic polymer.
25) The plank of claim 24 wherein said acrylic polymer is
chemically cross-linked.
26) The plank of claim 22 wherein said capstock comprises an
anti-slip coating.
27) The plank of claim 26 wherein said anti-slip coating is
chemically crosslinked.
28) The plank of claim 26 wherein said anti-slip coating comprises
grit.
29) The plank of claim 13 wherein said tread surface is
cambered.
30) The plank of claim 23, wherein said camber has a slope of about
1 degree of arc, said slope being measured from plank center to
plank edge.
31) An anchor structure that can be used to install a plank having
a flange in a deck or platform, the anchor comprising a base and
extending from the base a vertical member having an installation
hardware aperture, and extending substantially horizontally from
the vertical member, a transverse member, the transverse member
positioned at an angle that departs from the horizontal by at least
5.degree..
32) The anchor of claim 31 wherein said base member comprises an
extended base member.
33) The anchor of claim 31 wherein the aperture is configured to
accept a screw fastener.
34) The anchor of claim 33 wherein the aperture is further
configured to retain a screw fastener.
35) A decking structure comprising: (a) a support, (b) one or more
hollow profile deck members, the members free from an installation
slot, each member comprising a tread surface, a parallel opposite
support surface and an anchor flange on opposite edges of the
member; and (c) one or more anchors that can cooperate with the
profile flange in the installation of the profile on the support,
the anchor comprising means to attach the anchor to the support
using an anchor base portion, the anchor further comprising a
vertical member extending from the base portion ending in a
transverse portion, the transverse portion extending from the
vertical portion forming an anchor flange that can interact with
the profile flange in installing the member on the support; wherein
said deck members are attached to said support by engaging said
anchor flanges within the region partially enclosed by said anchor
base, vertical, and transverse members and then attaching said
anchor base members to said support via said attaching means and
upon attachment to said support, longitudinal expansion and
contraction of said deck members is not constrained by said
anchors.
36) The structure of claim 35 wherein said deck members are hollow
planks further comprising an extruded thermoplastic-biofiber
composite material, said plank including at least one internal arch
support structure, wherein said plank has a compressive strength of
at least 1500 pounds per square inch (10 megapascals) and a
coefficient of thermal expansion of less than about
1.5.times.10.sup.-5 inch per inch .degree. F.
37) The structure of claim 36, wherein said attachment means
comprises screws.
38) The structure of claim 36, wherein said anchors substantially
engage said anchor flanges the entire length of said planks.
39) The structure of claim 36, wherein said plank tread surface is
cambered.
40) The structure of claim 39, wherein said camber has a slope
greater than about 1 degree of arc, said slope being measured from
plank center to plank edge.
41) The structure of claim 36 wherein said anchor base and
transverse members include two or more distinct widths whereby the
spacing between planks can be varied to produce a variety of
predetermined patterns.
42) The structure of claim 36, further comprising distinct end
capping and edge capping trim members attached to the periphery of
said structure.
43) The structure of claim 36, wherein said support comprises
joists.
44) The structure of claim 36, wherein said planks include
mortise-tenon joints.
45) The structure of claim 36, further comprising an underlayment
of insect screen between said support and plank installation
surfaces.
46) The structure of claim 36, further comprising one or more
fasteners installed to fixedly attach said planks to said support
structure whereby: (a) longitudinal movement of said planks is
constrained at the points of fixed attachment, and (b) length
changes induced by environmental fluctuations in temperature and
humidity are partitioned into zones adjacent said points of fixed
attachment.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a system for forming a surface
suitable for human occupation or use such as a deck or platform.
The invention includes an installed deck or platform. The invention
also includes a construction system including an extruded plank for
a deck or platform formed from system components including a plank
and an anchor. The invention also includes a construction system
including an extruded plank for a deck or platform. The plank
having an internal structure and exterior installation components,
that can be combined with an anchor structure during installation.
These components can interact in the decking structure to result in
a deck or platform that can resist the undesirable effects of sun,
weathering and hard use. The installation, construction and use of
platforms or decks have come increasingly important in commercial,
institutional, residential and other construction locations. Such
platforms or decks are commonly installed during original
construction or can be retro-installed in improvement projects.
Decks provide use for commercial activities, recreational
activities, farm activities, manufacturing activities and other use
modes. A variety of installation systems for such decking
structures have become common.
BACKGROUND OF THE INVENTION
[0002] Wood, vinyl and metal components in the form of planking or
decking components have been a primary focus of deck and platform
manufacture over the last few years. Such systems are extruded from
resin or aluminum or are milled from stock. Both sized lumber,
plywood or chipboard materials have been used in decking systems.
Such systems are typically installed by nailing or screwing
individual planks or sheets of material to a support or foundation
structure. Such wood products and even plywood and chipboard
materials have become increasingly expensive due to cost and
scarcity of components. Hollow profile vinyl components have also
been suggested, but suffer from substantial structural and thermal
drawbacks. Metal components of aluminum and steel are common but
are not generally considered to be of more than utility grade
materials.
[0003] Composite thermoplastic fiber materials have been suggested
for use as a replacement for vinyl wood products. Such materials
have enjoyed increasing utility in the prior art. A family of
patents related to thermoplastic fiber composites are shown in U.S.
Pat. Nos. 5,441,801, 5,497,594, 5,539,027, 5,827,607, 5,932,334,
5,948,524, 6,004,668 and 6,015,612 and others relating to
thermoplastic composites using a biofiber such as a wood fiber in a
high strength profile or structural member. When using such
materials as a replacement for wood, the materials must be used in
a decking system in a form that can be assembled with relative
ease, can support the weight and dynamic load from its occupants
and can have an extended useful life. The material should be
capable of economic manufacture, ease of storage and transport and
can be readily installed with simple hand tools in the field.
[0004] Apart from the planking systems, installation systems that
can be used to secure a plank to a support structure are also known
in the art. An array of wooden, metallic and vinyl installation
components are known. Decking and installation hardware are shown,
for example, in Svensson, U.S. Pat. No. 5,033,147, showing a bridge
deck slab having a tongue and groove attachment for adjacent bridge
deck slabs and an anchor bolt system that interacts with a single
installation flange of one bridge deck slab. The Svensson bridge
decks are typically aluminum structures that can endure vehicular
traffic on bridge construction. Pollack, U.S. Pat. No. 5,613,339,
shows an extruded two part deck plank structure. A first part
comprises an elongate bottom "pan-shaped" deck plank member adapted
for installation on a support. The second portion comprises a cover
for the shaped deck plank. The deck plank is installed using
conventional screws or other attachment means and adjacent deck
planks are not connected during installation. Johnson, U.S. Pat.
No. 5,953,878, shows hollow profile decking systems that use an
anchor that engages a slot formed in the edges of adjacent deck
planks that cooperate to hold the deck planks in place and maintain
the appropriate spacings between planks. The slots are either
formed along the entirely of the edge or are formed at specific
locations in the plank edge. These systems use no anchor systems
that cooperatively interact with a flange.
[0005] Erwin et al., U.S. Pat. No. 5,660,016, describes a decking
system constructed of foam-filled, extruded plastic decking planks
attached to support structure by means of clamps or hold-down
blocks that engage a flange along the side of each plank.
[0006] A substantial need exists in establishing a structurally
strong, low cost, easily installed decking structure.
BRIEF DISCUSSION OF THE INVENTION
[0007] The invention comprises a variety of aspects including a
platform or decking system, an installed platform or deck, an
extruded hollow profile deck plank and an anchor system in a
cooperative kit. The deck plank of the invention comprises an
extruded hollow profile in the form of a uniformly sized unit with
integrally formed anchor flanges and planar surfaces. The plank
comprises a composite of a thermoplastic and a biofiber. The
planking unit of typical planking dimensions can have coplanar
surfaces comprising a tread surface and an opposite installation or
support surface that is installed in contact with a base support or
foundation. Along the edges of the plank, anchor flange components
are formed for installation purposes that can cooperate with an
anchor unit. The tread surface is a surface configured for and
exposed to traffic by a user. The plank is extruded in a form that
has substantial strength arising from the formation and shape or
configuration of internal support webs positioned between the tread
surface and the installation or support surface to provide
compression strength suitable to survive hard use by users of the
installed platform or deck.
[0008] The anchor units comprise a structure adapted to be attached
to a support structure or foundation with conventional attachment
hardware. The anchor structure uses an anchor flange that interacts
with a complementary flange on the plank or deck member without
using a slot based installation. The anchor structure additionally
contains a generally T-shaped structure having a base that contacts
the support or foundation, a vertical member extending from the
base ending in a "T-shaped" transverse member. The T-shaped
transverse member is shaped and configured to cooperate with the
anchor flanges of the plank edge to hold the plank or planks of
decking system in place during installation and use. The base can
also comprise a transverse base portion. One anchor unit interacts
with adjacent typically parallel, appropriately spaced apart planks
to form a deck or platform portion. In a preferred mode, the anchor
flange extends from the plank at the installation surface of the
plank, proximate the installation surface and is placed at an angle
that departs from the horizontal upwardly from the installation
surface by at least 5.degree.. The T-shaped anchor structure is
angled to conform to the flange position and departs from the
horizontal by a similar angle. The angle of the transverse portion
of the T-shaped member matches, (i.e.) is substantially parallel
to, the anchor flange at a surface or zone of interaction between
the flange and anchor member. The T-shaped anchor member can also
contain an extended or transverse base portion that extends from
the base, provides reliable support and stability and cooperates
with other anchor parts and encloses the anchor flange of the
plank. The anchor can be in the form of an H-shaped or an I-shaped
member. See FIG. 1, showing a modified T-shape or an I-shaped
member. The form can take a number of shapes depending on overall
dimensions and sizing of the individual portions of the member.
[0009] The deck planking units of the invention comprise a deck
plank having an internal support structure sufficient to maintain
the dimensions of the plank under structural load conditions. The
internal profile structure comprises vertical support webs in a
hollow structure that provide mechanical integrity by extending
from the tread surface to the installation surface and are of
sufficient size and extent to maintain the mechanical integrity of
the plank. Preferably the internal support webs comprise arched web
members co-extruded into the interior of the plank. The aches are
formed in the plank with the arches positioned in a support
configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1 through 3, 10 and 13 are isometric, top and end
views of the anchor structure of the invention used to hold the
deck plank extruded profile of the invention in place on a support
surface.
[0011] FIGS. 4 and 5 are end views of two embodiments of the deck
plank hollow profile extruded unit with varying anchor flanges. In
FIG. 5, two of the deck plank extruded profiles are shown installed
using an anchor flange and an anchor of the invention held in place
with a fastener.
[0012] FIG. 6 is a substantially isometric view of the plank of the
invention showing the installation surface, the internal support
structure and the anchor flanges.
[0013] FIGS. 7 and 12 show an alternate decking member and a trim
piece. The member with legs forms a space that cooperates with a
trim piece and its constituent parts to form an attractive and
pleasing installation.
[0014] FIGS. 8 and 9 show alternate embodiments of the decking
member of the invention using mortise and tenon joinery to assemble
the decking system that can provide means to drain water from the
deck assembly. The mortise and tenon are milled into the profile of
the member and accept the shape in the milled portions made
available by the conformation of the member.
[0015] FIG. 11 shows an alternative installation of the decking
member of the invention.
[0016] FIG. 14 shows a trim piece adapted for insertion into the
open end of the deck member of the invention.
DETAILED DISCUSSION OF THE INVENTION
[0017] FIGS. 1, 10, and 13 show isometric views of the anchor
structure of the invention. Referring now to FIG. 1, the anchor
structure 10 is installed by placing the anchor structure on a
support surface. The anchor structure is placed on the base 11
interacting with the installation surface (not shown). The anchor
structure is then installed or fixed in place by inserting fastener
hardware through aperture 12. Anchor structure 10 comprises a base
portion having base 11 and an extended transverse base flange 15
forming a support area with a large surface area to ensure stable
installation. The anchor structure 10 has a vertical member or
portion 13 supporting a transverse portion comprising an anchor
flange 14 and a second anchor flange 14a. These anchor flanges 14
and 14a interact with the plank anchor flange (not shown, see FIGS.
4, 5, and 6) of a plank or of a second, adjacent deck plank.
[0018] FIG. 2 is a top view of the anchor structure 10 of FIG. 1.
In the center of the anchor structure is aperture 12 for the
insertion of a fastener. The aperture extends from the top of the
anchor structure through the base 11. At the edges of the top of
the anchor structure 10 of FIG. 2 are installation anchor flanges
14 and 14a. FIGS. 1 and 2 can be of any arbitrary length. In one
embodiment the anchor can be 0.25 to 10 inches in length. In
another embodiment, the anchor can be of a length to match the
installed length of one plank of the installation, i.e. 1 to 10
feet in length or more. In another embodiment the anchor can be
made in arbitrary long portion that can be cut to size to fit the
installed length of two or more planks, i.e., 5 to 50 feet, 6 to 25
feet or other selected installed length.
[0019] FIG. 3 is an end view of the anchor structure 10 of FIG. 1.
The installation aperture 12 is shown in phantom. The installation
base 11 and base flange 15 are shown. The vertical member 13 is
shown in conjunction with transverse portions or anchor flanges of
14 and 14a. A departure angle alpha is shown in FIG. 3 that
represents the departure from horizontal of flange 14a. This
departure angle alpha creates an interface area, zone or surface 59
at which the anchor flange 14a contacts the anchor flange of the
profile (not shown, see FIGS. 4 and 5) to form a stable
installation of the deck.
[0020] FIG. 4 shows one installed hollow profile deck member or
plank 40 of the invention. The deck member or plank 40 is installed
in place using an anchor 10 and an anchor/trim piece 49. The anchor
10 is held in place with a fastener (an appropriately sized screw)
58. The anchor/trim piece 49 hides the edge portion of the deck
plank and holds the anchor flange 45 in place for a mechanically
stable installation (compare the anchor flange 45 of FIG. 4 to the
flange 55 of FIG. 5). The anchor flange 40 is parallel to the
support surface 48 (in phantom). Hollow profile extruded deck plank
40 comprises a tread surface 41 and an installation surface 42 in
contact with the installation support surface or base 48 (in
phantom). The deck plank 40 has anchor flanges 45 that cooperate
with the anchor structure to provide a structurally sound
installation while permitting longitudinal expansion and contract
of the plank in its end use environment. The structural integrity
and mechanical compressive strength of the deck plank is maintained
using support webs 43 and arc support portion 44 of the deck member
or plank in the form of a hollow profile 40. The formation of the
support webs 43 and arc support portions 44 results in the
formation of various hollow profile apertures or openings 46 and 47
formed in the structure during extrusion.
[0021] FIG. 5 shows the installation of two parallel, spaced apart
hollow profile deck plank structures 50 of the invention. Plank
structures 50 use an anchor flange 55 with a unique configuration
(compared to the plank 40 and flange 45 of FIG. 4) on a base or
support surface 60 (in phantom) using the anchor structure 10 and a
fastener 58. The deck profiles 50 are installed on a base or
support surface 60. The hollow profile planks 50 interact with the
base or support surface 60 using plank installation surface 52 of
the deck plank 50. The deck plank comprises a tread surface 51 to
support user traffic, internal support webs 53 and arc like support
structures 54. The deck plank 50 comprises an anchor flange 55
having a cooperating shape that matches the shape of the transverse
portion or anchor flange 14 or 14a of the anchor 10. The transverse
portion or anchor flange 14 or 14a of the anchor 10 has a
cooperative interface that contacts a similarly shaped surface on
the anchor flange 55. The transverse portion or anchor flange 14 or
14a interacts with the anchor flange 55 at an interface area,
surface or zone 59. The formation of the arc like support structure
54 and vertical support webs 53 results in the formation of
aperture or openings 56 and 57 that are formed within the plank
structure to provide controlled weight while preserving high
strength. The planks 50 can be extruded with a surface 51 adapted
to promote drainage. The center of the surface 51 can be elevated
above the edges to promote water flow toward the edges. Preferably
the top surface 51 of the plank 50 has a triangular shape. The
equilateral triangle shape has an apex along the centerline of the
plank with sides that slope toward the plank edge thus promoting
drainage. The angle at the apex is greater than about 170 degrees
of arc. The equal angles of the sides of the triangle to the
horizontal are about 0.5 to 5 degrees of arc, preferably about 0.75
to 2 degrees of arc. This relatively small angle promotes drainage
but does not interfere with use of the deck surface.
[0022] FIG. 6 is an isometric view of the plank 50 of the
invention. The plank installation surface 52 is shown. The plank 50
comprises the tread surface 51, the anchor flange 55, and the
vertical support webs 53 including the arc support structure 54.
The internal structure of the deck plank 50 includes openings 56
and 57 which remain after the extrusion of the deck structure 50
resulting from the extrusion die configuration.
[0023] FIG. 7 is an end view of an alternate embodiment of the deck
member 40a of the invention. Deck member 40a is similar to deck
member 40 with the addition to 40a of legs 77 that are formed in
the installation surface 42a of deck member 40a. The leg 77 holds
the deck member 40a above the rough surface 48 and creates a space
76 between the installation surface 42a and the rough surface 48.
The installation surface can provide ventilation, water drainage
and permits insertion of a tab or insert portion 78 of the trim
materials into the open space at each end of the deck member 40a.
FIG. 7 further displays a trim piece 79 and 79a. The trim piece can
be installed on the exposed sides of the deck member 40a or the
exposed (not in contact with any structure an obscured) opposite
ends or an end of the deck member 40a. Such a trim piece
participates in anchoring the deck member to the support surface 48
and cooperates with the anchor 10 to hold the deck members in
place. The trim piece 79 comprises a top piece 75 and a tab 78. The
top piece 75 forms a neat cover for the trim on the edge of the
deck while the tab contacts the support surface and can be inserted
into the trim tab space 76.
[0024] FIG. 8 is an end view of a deck member having a mortise and
tenon joint structure 84. The deck member is similar to that shown
in FIG. 6. The deck member additionally comprises a capstock,
coating, anti-skid surface, or an UV or wear protective surface 80
covering the exposed tread surface with a protective or colored
coating or layer. The mortise and tenon deck member has a mortise
81 formed in the end of the deck member 84. The mortise has a top
surface 82 and a bottom surface 82a. The base or wall 85 of the
mortise is also shown. The mortise is sized and configured to
accept the tenon 90 shown in FIG. 9.
[0025] FIG. 9 shows the tenon, a projection portion of the mortise
and tenon containing member 84 and shows FIG. 8 (in phantom). The
tenon comprises a tenon top 91, a tenon bottom 92 formed in the
composite material of the deck member 84. As can be readily
appreciated from the Figure, the tenon is not a continuous tenon
across the width of the deck member, but is formed in the material
remaining after the deck member is extruded with the interior
structure shown in FIGS. 4, 5, and 6. However, the tenons are
shaped and configured to fit into the mortise shown in FIGS. 8 and
9. Further, the length of the tenon and the depth of the mortise
are shaped and configured to leave a aperture or gap 93 between the
ends of the joined deck members 84. The gap 93 preferably acts as a
water drain permitting water to drain from the tread surface 41 or
capstock layer or coating 80 through the decking member 40 or 84.
The drainage water can be directed to further drains in the support
surface or base 48 or to the environment below the deck structure.
The tenon 90 can be inserted into the mortise 81 (shown in phantom)
and can provide structural support simply by its insertion.
Alternatively, the mortise and tenon can be joined using an
adhesive material to bond the mortise and tenon structure securely
to cooperate with the anchor 10 and trim piece 79 to form a secure
structure. In an alternative embodiment of the invention,
applicants envision planks having the mortise and tenon formed in
opposite plank ends so that planks of various lengths can be
readily formed from standard length stock by simply cutting a
pre-determined length of material from the plank center, reversing
the plank halves, and assembling the joint interior to the
foreshortened plank.
[0026] FIG. 10 additionally displays a sloped support 17 between
base 11 and transverse portions/anchor flange 14. FIG. 10 shows a
base portion 11 and a two-part base flange 15 and 15a. In FIG. 10,
vertical member 13a comprises a cylindrical portion formed into the
one piece anchor 100 of FIG. 10.
[0027] FIG. 11 shows the installation of a deck member 40 ripped
lengthwise leaving a ripped surface 111 installed on an
installation surface 42 using hardware 112 and the anchor 100 of
FIG. 10.
[0028] FIG. 12 shows an alternate embodiment of the installation
similar to that in FIG. 7. The deck member 40a is shown ripped
lengthwise leaving a ripped surface 111 and installed using the
anchor 100 of FIG. 10 and the trim piece 79 of FIG. 7 installed
with a screw fastener 49a.
[0029] FIG. 14 is an end trim piece 140 adapted to cover the end of
a deck member 50. The trim piece 140 has an end cover portion 141
and one or more insert portions 142. The inset insert portions 142
are adapted for a snug friction fit to the hollow profile 56
section of the deck member 50. When used, the trim piece 140 is
brought into contact with deck member 50 and the inserts 142 are
inserted into the hollow profile 56. The end cover 141 covers the
entire exposed end portion of the deck member 50. The insert 142
comprises a base portion 143, a curved top portion 144 and a
vertical connecting portion 145. When the insert 142 is inserted
into the hollow profile 56, the curved portion 144 contacts the
arched support section 54 of the hollow profile 56 while the base
portion 143 contacts the base portion of the hollow profile. The
vertical member 145 provides mechanical integrity to the insert 142
that maintains the trim piece 140 in place.
[0030] Plank Structure
[0031] The plank structure of the invention preferably comprises a
composite comprising a thermoplastic resin and a biofiber; however,
hollow plastic and metal planks are envisioned as falling with the
scope of the invention. The thermoplastics that can be used include
polyolefins such as polyethylene or polypropylene or other
thermoplastic polymers such as polyvinyl chloride, polystyrene,
polyacrylic materials, polyester materials and other common
thermoplastics. In manufacturing the preferred composite of the
invention, the thermoplastic and fiber are blended, often in dry
form, and then introduced into an extruder in which the materials
are intimately blended, melted and formed into a composite material
as described in greater detail hereinbelow. Often, the structural
components of the invention are directly extruded from the initial
blending of these materials or can be first extruded in the form of
a pellet which then can be introduced, in turn, into a plank
forming extruder device at a later time or different location.
[0032] The composite materials of the invention, formed into a
plank can be manufactured using a surface layer, protective
coating, capstock layer on any surface, portion thereof on the
exterior or interior of the decking member or plank. The coating,
layer, or capstock can provide environmental stability, wear
resistance, resistance to environmental moisture, stability to
ultraviolet light or any other physical or chemical property that
can tend to improve the wear ability or lifetime of any aspect of
the deck plank structure. Extruded capstock materials are known for
use in the formation of extruded hollow profile materials.
Coextruding a layer of an acrylic, a chloropolymer, a
fluoropolymer, or other blended polymeric material that can
maintain the surface quality of the profile typically makes an
effective protective layer. A representative abrasion resistant
coating is LUCITE.RTM. TufCoat 4600, available from ICI Acrylics,
Memphis, Tenn. Capstocks can have a clear, colored or patterned
appearance. The colors can be formed by the addition of dyes and/or
pigments to the capstock layer to form a green, Terratone, white,
or other colored appearance. Further, the capstock can take the
appearance of a wood grain, a stone-like appearance or other
natural surface quality. Such capstock layers are typically
manufactured by coating, painting or coextruding the thermoplastic
material in a thin layer onto the plank during the extrusion of the
plank material. During extrusion, the capstock layer is typically
carefully gauged in thickness to conserve material but to provide
an excellent surface and acceptable appearance (less than two
millimeters, typically less than 1 millimeter).
[0033] The deck plank can also be manufactured with a roughened or
substantially non-skid surface. Preferably, the tread surface of
the plank can be supplied with an anti-skid surface. Such anti-skid
surfaces can be manufactured in a number of ways. First, a capstock
layer can be manufactured with a substantial wood grain relief or
substantial rough surface. Such a surface can be substantially
non-skid and can prevent accidental slipping accidents.
Alternatively, the tread surface of the deck can be supplied with a
grit or particulate material to enhance slip resistance. The grit
or particulate can be bonded to the tread surface using
conventional bonding agents. In the manufacture of such particulate
non-skid surfaces, the particulate and the bonding agent are
typically applied to the surface, the bonding agent is cured (using
catalysts, UV or electron beam radiation, heat or other curing
means) to form a solid phase from the originally applied liquid
phase, binding the particulate to the surface. The order of
addition of the materials is optional depending on the nature of
the add-on materials. Either the binder or the particulate can be
added to the surface or the binder and the particulate can be
blended into a uniform dispersion of the particulate and the
liquid. This uniform dispersion can be applied to the surface and
cured in place to form a hard, non-skid, durable surface.
[0034] The inclusion of means to drain the surface of the
accumulation of water is an important aspect and can be used with
an appropriately shaped plank profile. Water can accumulate as a
result of rain fall, washing and/or rinsing of the deck surface or
from accidental spray from lawn sprinkling, house cleaning, car
washing or other accidental water sprays. The substantially flat
surface of the deck can accumulate substantial quantities of water.
Obtaining drainage of accumulated water is important. Drainage can
be promoted by forming a camber in the tread surface of the plank
such that the plank is the highest at its center. Any water falling
on such a cambered surface will be forced by gravity to run off the
plank from the center to the edge. A center-to-edge camber having a
slope equal to, or greater than, one degree slope (1.degree.) is
sufficient to promote the required drainage. Furthermore, the
spacing between planks affects drainage efficiency. The spacing
between planks should be sufficient to overcome the plugging
effects of surface tension and small amounts of accumulated dirt
and debris arising in the use environment. Applicants envision
installations where it may be advantageous to introduce apertures
into the planks per se to pass water from the top surface, or
through the plank sides, into the hollow arched regions, enroute to
a second set of exit apertures in the plank installation surface.
Such apertures can be in the form of holes or by forming gaps at
the site of assembly of one plank with another at a joint or plank
end.
[0035] In installations where the anchor extends contiguously the
entire length of the plank (to provide extra support in demanding
applications), drain apertures in the form of holes can be formed
in the anchor. The diameter and spacing of such drains should not
compromise the structural integrity of the anchor. The diameter of
the drains should be large enough to prevent capillary bridging due
to surface tension effects and permit drainage of small particle
debris as described above. Conceivably, the spacing between planks
could be great enough to accommodate passage of small quantities of
pine needles, acorns, leaves, twigs, and the like providing a
limited "self-cleaning" flushing of the deck surface. On the other
hand, the apertures in the anchors would pass only water-soluble
debris and small insoluble dirt particles. Spacing of the drains
should be related to the volume of water to be drained per unit
area of deck surface during a heavy rainfall. While not wishing to
limit the scope of the invention by the following disclosure,
applicants believe useful "rules of thumb" for determining proper
drainage are: a flow rate of about 5 gallons per hour per square
foot of deck surface, and aperture areas of about 3/8 square inch,
which provide sufficient drainage if the apertures are not
elongated to the point where water is retained by capillary
action.
[0036] Finally in installations where the decking structure forms
the floor of a larger enclosed structure, inter-plank spacing can
be eliminated to prevent intrusion of insects since water drainage
is not a problem an interior decking structure. Alternatively, an
underlayment of insect screening can be installed between support
and plank installation in installations where ventilation through
the inter-plank gaps is desired.
[0037] Thermoplastic Polymer-Biofiber Composite Materials
[0038] Polymer Resin
[0039] A polyolefin composite combines about 5 to 50 parts of a
polyolefin such as a polyethylene or polypropylene homopolymer or
copolymer with greater than about 50 to 90 parts of a fiber having
an aspect ratio greater than about 2. The useful polyolefin
material is a polyethylene or polypropylene polymer having a
melting point of about 140 to 160.degree. C., preferably about 145
to 158.degree. C. The preferred polyethylene material is a
polyethylene homopolymer or copolymer with 0.01 to 10 wt % of a
C.sub.2-16 olefin monomer. The preferred polypropylene material is
a polypropylene homopolymer or copolymer with 0.01 to 10 wt % of
ethylene or a C.sub.4-16 olefin monomer or mixtures thereof. Having
a melt index greater than 0.5 g-10 min.sup.-1 preferably about 2 to
20 g-10 min.sup.-1 by ASTM 1238. The composite is also
compatibilized using a compatibilizing agent that promotes the
desired intimate contact between polymer and fiber whereby fiber
particles are completely encapsulated by a continuous polymer
phase. The biofiber is dried to a content of less than about 5000
parts, preferably less than 3500 parts of water per each million
parts of fiber (PPM) to promote the desired encapsulated morphology
which applicants believe results from opening fiber cellular
structure to wetting and penetration by fluidized thermoplastic
polymer. The combination of these factors results in a composite
having surprisingly improved structural and thermal properties. A
representative polypropylene random copolymer is Montell SV-258.
Representative compatibilizers are Eastman Epolene.TM. Series--E43,
G3003, G0315, etc.
[0040] The composite can also comprise a polyvinyl chloride and
biofiber composite. Polyvinylchloride (PVC) is a common commodity
thermoplastic polymer that can be used in the composite. PVC
homopolymers in a variety of molecular weights (K values) are
readily available from a number of sources, GEON and Shin-Tech, for
example. Polyvinylchloride can also be combined with other vinyl
monomers in the manufacture of polyvinyl chloride copolymers. Such
copolymers can be linear copolymers, branched copolymers, graft
copolymers, random copolymers, regular repeating copolymers, block
copolymers, etc. Monomers that can be combined with vinyl chloride
to form vinyl chloride copolymers include a acrylonitrile;
alpha-olefins such as ethylene, propylene, etc.; chlorinated
monomers such as vinylidene dichloride, acrylate monomers such as
acrylic acid, methylacrylate, methylmethacrylate, acrylamide,
hydroxyethyl acrylate, and others; styrenic monomers such as
styrene, alphamethyl styrene, vinyl toluene, etc.; vinyl acetate;
and other commonly available ethylenically unsaturated monomer
compositions.
[0041] Such monomers can be used in an amount of up to about 50
mol-%, the balance being vinyl chloride. Polymer blends or polymer
alloys can be useful in manufacturing the pellet or linear
extrudate of the invention. Such alloys typically comprise two
miscible polymers blended to form a uniform composition. Scientific
and commercial progress in the area of polymer blends has lead to
the realization that important physical property improvements can
be made not by developing new polymer material but by forming
miscible polymer blends or alloys. A polymer alloy at equilibrium
comprises a mixture of two amorphous polymers existing as a single
phase of intimately mixed segments of the two macro molecular
components. Miscible amorphous polymers form glasses upon
sufficient cooling and a homogeneous or miscible polymer blend
exhibits a single, composition dependent glass transition
temperature (T.sub.g). Immiscible or non-alloyed blend of polymers
typically displays two or more glass transition temperatures
associated with immiscible polymer phases. In the simplest cases,
the properties of polymer alloys reflect a composition weighted
average of properties possessed by the components. In general,
however, the property dependence on composition varies in a complex
way with a particular property, the nature of the components
(glassy, rubbery or semicrystalline), the thermodynamic state of
the blend, and its mechanical state whether molecules and phases
are oriented. Polyvinyl chloride forms a number of known polymer
alloys including, for example, polyvinyl chloride/nitrile rubber;
polyvinyl chloride and related chlorinated copolymers and
terpolymers of polyvinyl chloride or vinylidene dichloride
polyvinyl chloride/alphamethyl styrene-acrylonitrile copolymer
blends; polyvinyl chloride/polyethylene; polyvinyl
chloride/chlorinated polyethylene and others. The primary
requirement for the substantially thermoplastic polymeric material
is that it retain sufficient thermoplastic properties to permit
melt blending with wood fiber, permit formation of linear extrudate
pellets, and to permit the composition material or pellet to be
extruded or injection molded. Useful PVC resin blends (including
foaming agent and stabilizers) and extrusion conditions therefore
are described by Suzuki et al. in U.S. Pat. No. 5,712,319 the
disclosure of which is hereby incorporated by reference.
[0042] Biofiber
[0043] A variety of biofiber materials can be used in the
composites of the invention. Such fibers are fibers of naturally
occurring sources that have significant aspect ratio to provide
structural properties of the composite. Such fibers include wood
fiber, flax, cotton, bagasse, wood flour, straw, recycled fiber,
pulp, or other cellulosic material, etc. Wood fiber, in terms of
abundance and suitability can be derived from either soft woods or
evergreens or from hard woods commonly known as broad leaf
deciduous trees. Soft woods are generally preferred for fiber
manufacture because the resulting fibers are longer, contain high
percentages of lignin and lower percentages of hemicellulose than
hard woods. While soft wood is a primary source of fiber for the
invention, additional fiber make-up can be derived from a number of
secondary or fiber reclaim sources including bamboo, rice, sugar
cane, and recycled fibers from newspapers, boxes, computer
printouts, etc.
[0044] However, the primary source for wood fiber of this invention
comprises the wood fiber by-product of sawing or milling soft woods
commonly known as sawdust or milling tailings. Such wood fiber has
a regular reproducible shape and aspect ratio. The fibers based on
a random selection of about 100 fibers are commonly at about 0.1 to
3 mm in length, 0.05 to 1 mm in thickness and commonly have an
aspect ratio of at least 1.8, preferably 2.5 to 7.0. The preferred
fiber for use in this invention is fiber derived from processes
common in the manufacture of windows and doors. Wooden members are
commonly ripped or sawed to size in a cross grain direction to form
appropriate lengths and widths of wood materials. The by-product of
such sawing operations is a substantial quantity of sawdust. In
shaping a regular shaped piece of wood into a useful milled shape,
wood is commonly passed through machines which selectively removes
wood from the piece leaving the useful shape. Such milling
operations produce substantial quantities of sawdust or mill
tailing by-products. Furthermore, substantial waste trim is
produced when shaped materials are cut to size and subsequently
have mitered joints, butt joints, overlapping joints, mortise and
tenon joints formed therein. Such process produce large trim pieces
which can comminuted by well-known methods to form wood fiber
having dimensions approximating sawdust or mill tailings. Blending
of wood fibers with other biofibers (all of which may have
different particle sizes and particle size distributions) is
envisioned as falling within the scope of the present invention.
Alternatively, the fiber stream can be pre-sized, or can be sized
after blending, to yield input fiber have a preferred size and size
distribution. Finally, the fiber can be pre-pelletized before use
in composite manufacture.
[0045] Frequently the waste trim pieces and sawdust material
contains substantial proportions of other materials used to make
wood sashes and frames for windows and doors including, but not
limited to, for example, polyvinyl chloride or other polymer
materials that have been used as coating, cladding or envelope on
wooden members (about 10 wt %); recycled structural members made
from thermoplastic materials; polymeric materials from coatings;
adhesive components in the form of hot melt adhesives, solvent
based adhesives, powdered adhesives, etc.; paints including water
based paints, alkyd paints, epoxy paints, etc.; preservatives,
anti-fungal agents, anti-bacterial agents, insecticides, etc., and
other non-wood materials (ONWM) used in the manufacture of wooden
doors and windows. The ONWM content is commonly less than 25 wt-%
of the total biofiber input into a preferred polyvinyl chloride
wood fiber product. Commonly, the intentional recycle ranges from
about 1 to about 25 wt-%, preferably about 2 to about 20 wt-%, most
commonly from about 3 to about 15 wt-% recyclable ONWM based on the
weight of input biofiber.
[0046] Pellet
[0047] The thermoplastic resin and biofiber can be combined and
formed into a pellet using thermoplastic extrusion processes. Fiber
can be introduced into pellet making process in a number of sizes.
We believe that the biofiber (when wood fiber) should have a
minimum length of at least 0.1 mm because wood flour tends to be
explosive at certain wood to air ratios. Further, wood fiber of
appropriate size of an aspect ratio greater than 1, preferably
greater than 2, tends to increase the physical properties of the
extruded structural member. However, useful structural members can
be made with a fiber of very large size. Fibers that are of
reinforcing length up to 3 cm in length and 0.5 cm in thickness can
be used as input to the pellet or linear extrudate manufacturing
process. However, particles of this size do not produce highest
quality structural members or maximized structural strength. The
best appearing product with maximized structural properties are
manufactured within a range of particle size as set forth below.
Further, large particle wood fiber an be reduced in size by
grinding or other similar processes that produce a fiber similar to
sawdust having the stated dimensions and aspect ratio. One further
advantage-of manufacturing sawdust of the desired size is that the
material can be pre-dried before introduction into the pellet or
linear extrudate manufacturing process. Further, the wood fiber can
be pre-pelletized into pellets of wood fiber with small amounts of
binder if necessary.
[0048] During the pelletizing process for the composite pellet, the
thermoplastic resin and fiber are intimately contacted at high
temperatures and pressures to insure that the fiber and polymeric
material are wetted, mixed and extruded in a form such that the
polymer material, on a microscopic basis, coats and flows into the
pores, cavity, etc., of the fibers. During the extrusion process,
the fibers are substantially longitudinally oriented into the
extrusion direction by the extrudate flow profile. Such substantial
orientation causes overlapping of adjacent parallel fibers and
polymeric coating of the oriented fibers resulting a reinforced
material that has substantially improved mechanical properties such
as tensile strength, coefficient of thermal expansion, and a
modulus of elasticity.
[0049] Moisture control is an important element of manufacturing a
useful linear extrudate or pellet. Depending on the equipment used
and processing conditions, control of the water content of the
linear extrudate or pellet can be important in forming a successful
structural member substantially free of internal voids or surface
blemishes. The concentration of water present in the biofiber
during the formation of pellet or linear extrudate when heated can
flash from the surface of the newly extruded structural member and
can come as a result of a rapid volatilization, form a steam bubble
deep in the interior of the extruded member which can pass from the
interior through the hot thermoplastic extrudate leaving a
substantial flaw. In a similar fashion, surface water can bubble
and leave cracks, bubbles or other surface flaws in the extruded
member. Fiber sources when harvested, depending on relative
humidity and season, can contain from 30 to 300 wt-% water based on
fiber content. After cutting and drying the fiber can have a water
content of from 20 to 30 wt-%. Because of the variation in water
content of fiber source and the sensitivity of extrudate to water
content, the control of water to a level of less than 8 wt-% in the
pellet, based on pellet weight, is important. When a structural
members, such as the decking plank of the present invention, is
extruded in non-vented extrusion process, pellets should be as dry
as possible and have a water content between 0.01 and 5 wt-%,
preferably less than 3.5 wt-%. When using vented equipment in
manufacturing the extruded linear member, a water content of less
than 8 wt-% can be tolerated.
[0050] The pellets or linear extrudate of the invention are made by
extrusion of the resin and fiber composite through an extrusion die
resulting in a linear extrudate that can be cut into a pellet
shape. The pellet cross-section can be any arbitrary shape
depending on the extrusion die geometry. However, we have found
that a regular geometric cross-sectional shape can be useful. Such
regular cross-sectional shapes include a triangle, a square, a
rectangle, a hexagonal, an oval, a circle, etc. The preferred shape
of the pellet is a regular cylinder having a roughly circular or
somewhat oval cross-section. The pellet volume is preferably
greater than about 12 mm.sup.3. The preferred pellet is a right
circular cylinder, the preferred radius of the cylinder is at least
1.5 mm with a length of at least 1 mm. Preferably, the pellet has a
radius of 1 to 5 mm and a length of 1 to 10 mm. Most preferably,
the cylinder has a radius of 2.3 to 2.6 mm, a length of 2.4 to 4.7
mm, a volume of 40 to 100 mm.sup.3, a weight of 40 to 130 mg and a
bulk density of about 0.2 to 0.8 gm/mm.sup.3.
[0051] We have found that the interaction, on a microscopic level,
between the resin, polymer mass and the fiber is an important
element of the invention. We have found that the physical
properties of an extruded member are improved when the polymer
melt, during extrusion of the pellet or linear member, thoroughly
wets and penetrates the wood fiber particles. The thermoplastic
material comprises an exterior continuous organic polymer phase
with the biofiber particle dispersed as a discontinuous phase in
the continuous polymer phase. The material during mixing and
extrusion obtains an aspect ratio of at least 1.1 and preferably
between 2 and 10, optimizes orientation such as at least 20 wt-%,
preferably 30% of the fibers are oriented in an extruder direction,
and are thoroughly mixed and wetted by the polymer such that the
exterior surfaces of the wood fiber are in contact with the polymer
material. This means, that pores, crevices, cracks, passageways,
indentations, etc., are filled by thermoplastic material. Such
penetration is attained by ensuring that the viscosity of the
polymer melt is reduced by operating at elevated temperature and
using sufficient pressure to force the polymer into accessible
internal pores, cracks and crevices within the biofiber in addition
to filling like features on the biofiber surface.
[0052] During the pellet or linear extrudate manufacture,
substantial work is done in providing a uniform dispersion of the
fiber into the fluidized polymer. Such work produces a substantial
number of orientable, acicular fiber particles. Such particles are
easily oriented into the extrusion direction by the flow field of
the extrusion process resulting in extrusion of parts having
improved structural properties.
[0053] The pellet dimensions are selected for both convenience in
manufacturing and in optimizing the final properties the extruded
materials. A pellet is with dimensions substantially less than the
dimensions set forth above difficult to extrude, pelletize and
handle in storage. Pellets larger than the range recited are
difficult to introduce into extrusion or injection molding
equipment, and are difficult to melt and form into a finished
structural member, such as a decking plank.
[0054] Composite and Pellet Manufacture-I
[0055] Thermoplastic polymer-biofiber composite material used to
produce the decking plank of the invention is made under high shear
conditions that are conducive to achieving intimate contact between
polymer and fiber that result in the unique physical and mechanical
properties exhibited in structural parts made from the composite.
Appropriate high shear conditions can be produced in a variety of
powder blenders and mixers. For example Nishibori uses a blade
mixer (U.S. Pat. No. 5,725,939) in tandem with an extruder to
produce biofiber composite sheet materials. Screw mixers,
especially extruders, are preferred processors ideally suited for
cascading continuous chemical process unit operations such as
heating, mixing, and devolatizing for example. Because small,
controlled volumes of material sequentially pass through isolated
zones along the screw(s) process parameters can be continuously
monitored and adjusted using microprocessors. Therefore, a
preferred process is the Krupp Werner & Pfleiderer (W & P)
KombiPlast process wherein a co-rotating, twin screw extruder is
used to make composite that is delivered to a single screw extruder
operating in tandem where composite is further heated and
compressed prior to delivery to an extrusion die. The die can be
either a profile die for direct extrusion of the inventive decking
plank or a pellet die.
[0056] The process steps used to make thermoplastic-biofiber
composite in a screw mixer generally begin with a fiber drying step
wherein biofiber is conductively heated under mild shear conditions
and the steam generated is vented from the mixer. Temperature, heat
transfer, and shear are closely controlled to optimize moisture
vaporization to avoid fiber scorching, breaking, and geysering at
the vent (at high moisture levels the steam generated blows fiber
out the vent in geyser like fashion). If it is necessary to cushion
the fiber during drying part or the entire thermoplastic can be
added with the fiber during the drying step. Fiber moisture is
preferably reduced to between 3 and 5 wt % during drying.
Thermoplastic and optional regrind material is added to dried fiber
at pre-selected point down the screw.
[0057] A "stuffer" screw may be used to add the thermoplastic
depending on the pressure in the barrel at the addition point,
which is related to the material throughput rate and compression.
The proto-composite is mixed and heated to distribute thermoplastic
throughout the fiber stream. Further downstream kneading blocks
shear mixes the composite. At this point, the thermoplastic melts
(polyolefins) or fluxes (PVC) to form a fluid mass capable of
forming a melt seal in the extruder. The temperature at this point
is typically 195-215 C for PVC composites. The fluid composite then
passes through a high free volume vacuum devolatization zone
operating at a vacuum of sufficient strength to remove volatile
products from the composite but of insufficient strength to pull
the composite apart (typically a negative pressure of from 50 to 90
kilopascals). During devolatization the compressed composite
abruptly expands and cools by as much as about 10.degree. C. such
that any thermal decomposition initiated during high shear mixing
is quenched. Expanding volatile products vented through a vacuum
port include, for example, steam, terpenes, lubricants,
stabilizers, and small amounts of hydrogen chloride (when PVC
comprises the thermoplastic). The expanded composite is
recompressed to further intimate contact between fiber and
thermoplastic before it is discharged into an evacuated transition
box between the twin and single screw extruders. Upon entering the
transition box, the composite now free of the confines of the
extruder screw(s) is free to expand and cool in three dimensions.
This expansion is sufficiently violent that some of the remaining,
unruptured biofiber cells that have become steam filled during
processing explode thus opening their interior volumes for
subsequent introduction of fluxed polymer. Newly formed volatile
products are evacuated at negative pressure in the range of from 50
to 95 kilopascals. Upon entering the single screw extruder, the
composite is compressed and heated to a pressure and temperature
dictated by operating requirements of the extrusion die. Optional
materials can be added to the composite at pre-selected points
along the single screw. For example, blowing agents can be added
when a foamed extrudate is desired similar to the method shown in
the flow chart (FIG. 1) and block diagram (FIG. 2) and more fully
described by Kamoski, U.S. Pat. No. 5,997,784, which is hereby
incorporated by reference.
[0058] When the composite is directly extruded through a profile
die to form the inventive decking plank, the die may be optionally
adapted to co-extrude capstock(s) on predetermined areas of the
extruded profile external surface. Such capstocks include, but are
not limited to, colored materials that enhance weatherability,
abrasion resistant coatings, friction promoting anti-slip coatings,
and the like.
[0059] Thermoplastic polymer-biofiber composite material is
visco-elastic. Upon exiting the die, the hot extruded part is more
a viscous fluid than an elastic solid. Important post extrusion
cooling and shaping process are applied to the part as it
transforms to become more an elastic solid than a viscous fluid as
it cools to ambient temperature. Therefore, the temperature, draw
down, and cooling rate of the extruded part are controlled to
minimize the residual stress in the finished part. Such "frozen in"
stresses gradually relax over time at different rates that depend
on the temperature of the end use environment. This stress
relaxation can cause a retinue of mechanical problems for
structures constructed from the extrude parts (profiles). Post
extrusion cooling and shaping (calibrating) processes and apparatus
are described by Purstinger, U.S. Pat. No. 5,514,325; DeCoursey et
al., U.S. Pat. No. 5,008,051; and Groeblacher, U.S. Pat. Nos.
5,578,328 & 5,484,577 the disclosures of which are hereby
incorporated by reference.
[0060] When the composite is extruded through a stranding die to
form pellets, the pressure, temperature, and cutter rotation speed
are adjusted to optimize pellet uniformity and density. Pelletizing
the composite permits decoupling of the composite making and
extrusion processes. Pellets can be extruded as described above for
the single screw portion of the W&P KombiPlast process, but
pellets are preferably extruded using counter-rotating, twin screw
extruders like the Cincinnati-Milicron CM-80, for example, that
develop high die head pressures at low screw rotation speeds.
Composite foaming, capstock co-extrusion, and down stream profile
cooling and calibration processes are identical to those for direct
profile extrusion described above.
[0061] In a variation of the process disclosed above, biofiber can
be dried, thermoplastic can be melted or fluxed, and the fiber and
plastic then mixed together separate extruders. Such multi-extruder
processes permit more precise control of the heat transfer during
heating and the shear during mixing. Such an approach reduces the
stress and comminution of acicular fiber particles that degrades
the particle size distribution of the fiber and mechanical
properties of structures made from the composite.
[0062] The high throughput process used to make
thermoplastic-biofiber composite operate at a rate of at mass flow
rates in the range of from about 10 to 5000 kg-hr.sup.-1 and are
capable of efficiently converts the maximum available mechanical
energy supplied by blade and/or screw mixers into composite.
However, the densification process further requires delivery of
this energy at a rate sufficient to overcome the energy barriers
opposing densification. Therefore the energy delivery of the
process occurs at a shear rate and for a time sufficient to force
thermoplastic into the biofiber cell interior without breaking
acicular fibers (or otherwise commuting/degrading the biofiber size
distribution). The desired composite morphology is one where the
fibers are surrounded and filled with thermoplastic to form a dense
void free material as opposed a porous, unfilled structure of
collapsed fibers that is to be avoided.
[0063] During extrusion of fluid composite through a profile die,
the torque exerted on acicular fibers by shear gradients tend to
rotate them in the flow direction thus producing a more aligned
morphology that generally improves the mechanical properties of the
resulting profile, the torque can easily exceed that required to
break the fiber. Therefore, when the input fiber is highly acicular
the shear rate, and/or the time spent by the material, in high
shear parts of the process are minimized to prevent excessive
particle breakage.
[0064] The versatility of W & P co-rotating, fully intermeshing
twin screw extruders used in the KombiPlast process is described in
greater detail by Marten et al. in U.S. Pat. No. 5,051,222. The
screw is designed in a segmented fashion so that a variety of
different screw elements can be placed on keyed shafts to achieve
the desired degree of mixing for a particular application. Screw
elements can vary along the length of the screw, but the two screws
must be matched to achieve fully intermeshing surfaces. Generally
speaking there are two different types of elements, screw conveying
elements and kneading or mixing disks. The screw elements can have
either a forward or reverse pitch, while the kneading disks can
have a neutral pitch in addition to the forward or reverse pitch.
The kneading disks consist of staggered elliptical disks that are
offset to achieve an overall conveying pitch. The disks can vary in
width from one element to another but are typically of uniform
width within an element. In addition to a varied pitch in the
kneading blocks, different screw elements can have different
conveying pitches. The worker skilled in the art would be able to
assemble an appropriate screw to achieve the optimum shear history
and conveying efficiency to result in the desired final
product.
[0065] As can be expected, all of the elements impart different
levels of shear history and conveying ability. These can be
summarized in the following list of elements and their relative
shear intensity:
[0066] Greatest Shear--Least Forward Conveying Efficiency
[0067] reverse pitch screw elements
[0068] reverse pitch kneading blocks
[0069] neutral kneading blocks
[0070] forward pitch kneading blocks
[0071] forward pitch screw elements
[0072] Least Shear--Most Forward Conveying Efficiency
[0073] In addition, wider kneading blocks imparts more shear to the
melt. Also tighter pitch imparts more shear. A worker skilled in
the art can combine all of these factors to design a screw that
maximizes shear input without thermally degrading the product.
[0074] In co-rotating, twin screw extruders preferred for
practicing the invention, the shear rate and residence time spent
by extrudate in the high shear (generally the kneading) zones of
the extruder is a complex interactive function of screw rotation
speed (RPM) and extruder screw/barrel geometry. However, the
following general observations are relevant:
[0075] For a given geometry the shear rate increases in direct
proportion to screw speed and narrowing of the clearance between
the tips of various screw elements and the extruder barrel
(affected by the degree of wear);
[0076] The residence time spent by the extrudate in the high shear
zone is determined by the degree of fill of the extruder screw and
the following interactive geometrical factors: 1) the width of the
narrow clearance zone (the number and width of kneading block
elements used in the screw design), 2.) the number of lobes on the
screw elements--(increasing number of lobes increases the volume of
material in the narrow clearance zone while simultaneously reducing
the free volume of lower shear zone between the tip and root of the
screw element); and 3.) the number and type of reverse
(left-handed) elements included in the screw design). Suitable
extruders useful for making thermoplastic polymer-biofiber
composite material are available from Krupp Werner Pfleiderer,
Leistritz, Davis Standard, and Entek Manufacturing, Inc.
[0077] Thermoplastic Polymer--Biofiber Composite Decking Planks
[0078] The preferred composite hollow decking plank includes an
exterior wall or shell substantially enclosing a hollow interior.
The interior can contain at least one structural web providing
support for the tread surface. The web is typically shaped by the
extrusion die and can take a variety of shapes with surface
contours adapted to support assembly. The interior webs support the
plank by distributing the applied load. The webs typically comprise
a wall, post, support member, or other formed structural element,
which increases compressive strength, torsion strength, or other
structural or mechanical properties. Such structural webs connect
the adjacent or opposing surfaces of the interior of the plank.
More than one structural web can be placed to carry stress from
surface-to-surface at the high stress locations of the application
to protect the plank from crushing, torsional failure or general
breakage.
[0079] After the plank is extruded and cut to length, any number of
additional shaping processes can be applied to the plank. For
example, the plank can have drilled apertures for passage of
fasteners such as screws, nails, etc. Such passageways can be
countersunk, metal line, or otherwise adapted to plank geometry or
the composition of the fastener materials. The planks can be milled
to introduce mating surfaces at the ends or edges thereof to
facilitate rapid assembly with other components of the decking
system having similar or different compositions with similarly
adapted mating surfaces. The plank exterior can have surfaces
adapted to an exterior trim and interior mating with trim pieces
and other surfaces formed into the exposed sides of the structural
member adapted to the installation of metal runners, wood trim
parts, door runner supports, or other metal, plastic, or wood
members commonly used in conjunction with a platform or deck.
[0080] Mechanical Properties
[0081] The minimum compressive strength for a weight bearing plank
member must be at least 1500 pounds per square inch (psi),
preferably 2000 psi as measured by ASTM D695. The compressive
strength is typically measured in the direction that load is
normally placed on the plank. The Young's modulus of the plank in
the extrusion direction should be about at least 500,000 psi,
preferably 800,000 and most preferably about 1.times.10.sup.6 psi
as measured by ASTM D3039.
[0082] Thermal Properties
[0083] We have found that the Coefficient of Thermal Expansion of
the thermoplastic polymer-biofiber composite materials useful in
practicing the invention is about 1.5.times.10.sup.-5 to
3.0.times.10.sup.-5 depending upon the proportions and homogeneity
of the materials as measured by ASTM D696. The Heat Deflection
Temperature is the temperature at which a standard test bar
deflects a specified amount under a stated load. The composite used
in the invention has a Heat Deflection Temperature of about 78
degrees Celsius at 1.82 megapascals and a Heat Deflection
Temperature of about 105 degrees Celsius at 0.46 megapascals as
measured by ASTM D648. The flash ignition temperature is the
minimum temperature at which sufficient flammable gas is emitted to
ignite momentarily upon application of a small external pilot
flame. The Flash Ignition Temperature of the composite is about 410
degrees Celsius as measured by ASTM D1929. The Self-Ignition
Temperature is the minimum temperature at which the specimen
spontaneously ignites in the absence of a flame ignition source.
The Self-Ignition Temperature of the composite is about 425 degrees
Celsius as measured by ASTM D1929. The Flame Spread Index is the a
number or classification indicating a comparative measure of
surface burning behavior derived from observations made during the
progress of the boundary of a zone of flame under defined test
conditions. The Flame Spread Index of the composite is about 10 as
measured by ASTM E84. The Average Flame Spread Index is a number
indicating a comparative measure of surface flammability of
materials using a radiant heat source under defined test
conditions. The Average Flame Spread Index of the composite is
about 22.7 as measured by ASTM E162.
[0084] Installation of the Decking System
[0085] The decking system of the invention can be assembled with a
variety of known mechanical fastener techniques. Such techniques
include screws, nails, and other hardware. When screws are used in
assembly, the diameter of the screw head versus the width of the
inter-plank spacing gap becomes an issue in some installation and
repair situations. Therefore, it is generally preferable that the
screw head diameter be less than inter-plank spacing. In
installations utilizing long length planks, longitudinal expansion
and contraction can be partitioned by fixedly attaching the plank
to the support surface by "toe-screwing", "toe-nailing", or
otherwise fixedly fastening the plank to the support structure. The
low coefficient of thermal (humidity) expansion and structural
strength of the thermoplastic polymer-biofiber composites, when
coupled with partitioning of potential bucking inducing length
changes, permits use very long length planks. The inventive decking
installations envision constraining longitudinal movement of the
planks at the points of fixed attachment thereby effectively
partitioning environmentally induced length changes into zones
adjacent the points of fixed attachment.
[0086] Components of the system can also be joined by use of: glue,
or a melt fusing technique wherein a fused weld forms a joint
between two decking components, or planks can be joined by inserts
adapted to fit with the interior web structure of the hollow plank.
The planks can be cut or milled to form conventional mating
surfaces including 90 degree(s) angle joints, rabbit joints, tongue
and groove joints, butt joints, etc. Such joints can be bonded
using an insert placed into the hollow profile that is hidden when
joinery is complete. Such an insert can be glued, thermally welded,
or heat staked into place. The insert can be injection molded or
formed from similar thermoplastics and can have a service adapted
for compression fitting and secure attachment to the structural
member of the invention. Such an insert can project from
approximately 1 to 5 inches into the hollow interior of the
structural member. The insert can be shaped to form a 90 degree(s)
angle, a 180 degree(s) extension, or other acute or obtuse angle
required in a deck assembly.
[0087] Further, non-load bearing components of the decking system
can be assembled by gluing components together with a solvent,
structural or hot melt adhesive. Solvent borne adhesives that can
act to dissolve or soften thermoplastic present in the components
and to promote solvent based adhesion or welding of the materials.
In the welding technique, once the joint surfaces are formed, the
surfaces of the joint can be heated to a temperature above the
melting point of the composite material and while hot, the mating
surfaces can be contacted in a configuration required in the
assembled structure. The contacted heated surfaces fuse through an
intimate mixing of molten thermoplastic from each surface. Once
mixed, the materials cool to form a structural joint having
strength typically greater than joinery made with conventional
techniques. Any excess thermoplastic melt that is forced from the
joint area by pressure in assembling the surfaces can be removed
using a heated surface, mechanical routing, or a precision knife
cutter.
[0088] Using these general assembly techniques, the deck or
platform of the invention is typically constructed by installing
deck planks on a support surface. Such support surfaces can often
comprise a concrete surface, a wood framing, I-beam joist framing,
a plywood subfloor on a frame support or any other suitable contact
surface. The decking is often cut to appropriate length and laid on
the surface. The anchor structures are then applied to engage the
anchor flanges of the planking and fastened to the underlying
support. Alternatively, the anchor structures can be installed on
the installation surface and the plank can be then inserted into
the anchors for appropriate assembly. Once a starter course of
anchor structure or plank is installed, further anchor structures
and planking can be added to the assembly until the deck surfaces
are fully assembled. Should a surface require a length of plank
longer than is available, the planks can be butt joined without
connection or can be assembled using glue inserts or other
conventional assembly techniques. Alternatively, the planks can be
mitered appropriately and fitted to avoid butt joinery.
[0089] Once the entire deck system is installed, the deck surface
can be appropriately treated, coated, painted or otherwise
finished.
[0090] The various embodiments described above are provided by way
of illustration only and should not be construed to limit the
invention. Those skilled in the art to which the invention most
closely pertains will readily recognize various modifications and
changes that may be made to the present invention without strictly
following the exemplary embodiments and applications illustrated
and described herein, and without departing from the true scope of
the present invention that is set forth in the following
claims.
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