U.S. patent application number 13/196808 was filed with the patent office on 2012-06-28 for filled polymer composite and synthetic building material compositions.
This patent application is currently assigned to CENTURY-BOARD USA LLC. Invention is credited to Wade Brown.
Application Number | 20120161351 13/196808 |
Document ID | / |
Family ID | 34795182 |
Filed Date | 2012-06-28 |
United States Patent
Application |
20120161351 |
Kind Code |
A1 |
Brown; Wade |
June 28, 2012 |
FILLED POLYMER COMPOSITE AND SYNTHETIC BUILDING MATERIAL
COMPOSITIONS
Abstract
The invention relates to composite compositions having a matrix
of polymer networks and dispersed phases of particulate or fibrous
materials. The matrix is filled with a particulate phase, which can
be selected from one or more of a variety of components, such as
fly ash particles, axially oriented fibers, fabrics, chopped random
fibers, mineral fibers, ground waste glass, granite dust, or other
solid waste materials. A system for providing shape and/or surface
features to a moldable material includes, in an exemplary
embodiment, at least two first opposed flat endless belts spaced
apart a first distance, with each having an inner surface and an
outer surface.
Inventors: |
Brown; Wade; (Mooresville,
NC) |
Assignee: |
CENTURY-BOARD USA LLC
Fort Myers
FL
|
Family ID: |
34795182 |
Appl. No.: |
13/196808 |
Filed: |
August 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11407416 |
Apr 20, 2006 |
7993552 |
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13196808 |
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10764012 |
Jan 23, 2004 |
7763341 |
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11407416 |
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Current U.S.
Class: |
264/45.3 |
Current CPC
Class: |
B29C 39/16 20130101;
C08L 2203/14 20130101; C08J 5/043 20130101; Y02W 30/91 20150501;
C08J 2375/08 20130101; C08G 18/4816 20130101; C08G 18/0895
20130101; C04B 26/16 20130101; C08G 2110/0066 20210101; C08K 3/22
20130101; Y10T 428/24438 20150115; C08G 2110/0083 20210101; C08J
5/04 20130101; Y10T 428/24479 20150115; C04B 26/16 20130101; C04B
14/42 20130101; C04B 18/06 20130101; C04B 18/08 20130101; C04B
38/0067 20130101; C04B 38/02 20130101 |
Class at
Publication: |
264/45.3 |
International
Class: |
B29C 44/12 20060101
B29C044/12 |
Claims
1. A method of continuously forming a highly filled molded
composite material comprising: mixing in a multi-zone extruder the
ingredients of the material by adding the ingredients of the highly
filled composite material to the various zones of the multi-zone
extruder without adding heat to the mixture, wherein the composite
mixture comprises: a monomeric or oligomeric poly or di-isocyanate
having a viscosity in the range of about 25 cp to about 200 cP at
25.degree. C.; a first polyol having a viscosity in the range of
about 480 cP to about 840 cP at 25.degree. C.; a second polyol
having a viscosity in the range of about 480 cP to about 840 cP at
25.degree. C.; a foaming agent; an inorganic particulate material
comprising about 60 wt % to about 85 wt % of the composite mixture,
wherein the particulate material provides filler material which
adds strength and reinforcement to the molded material and is added
to the mixture prior to forming; and a catalyst; extruding or
spraying the highly filled mixture by expulsion of the mixture
through a die onto or into a forming system, the forming system
comprising: at least a first and a second opposed mold belt spaced
apart a distance, each having an inner surface and an outer
surface; at least a first and a second opposed endless belt spaced
apart a distance, each having an inner surface and an outer
surface, wherein the inner surface of the first belt is contactable
with the outer surface of the first mold belt to move with and
support the first mold belt during molding, and wherein the inner
surface of the second belt is contactable with the outer surface of
the second mold belt to travel with and support the second mold
belt during molding; and a mold cavity defined at least in part by
the inner surfaces of the at least a first and a second opposed
mold belt; supporting the first and second opposed endless belts
with a pair of platens, each platen contacting and supporting the
outer surface of the endless belts along substantially the entire
length of the mold cavity; transferring the mixture along the mold
cavity by longitudinal movement of the opposed mold belts; exerting
substantially equal and continuous pressure on the mixture through
the opposed mold belts to mold the mixture; and removing the molded
material from the mold cavity after sufficient time has passed for
the mixture to cure or harden into the molded material, wherein the
molded material comprises a density of at least about 30
lb/ft.sup.3.
2. The method of claim 1, further comprising providing shape,
surface features, or both to the molded material.
3. The method of claim 1, further comprising embossing or
impressing a pattern on the mixture in the forming system.
4. The method of claim 3, wherein the pattern comprises a simulated
wood grain.
5. The method of claim 1, further comprising introducing fiber
rovings on, in, or beneath the surface of the mixture.
6. The method of claim 5, wherein the fiber rovings are axially
oriented fiber rovings.
7. The method of claim 1, wherein the inorganic particulate
material is fly ash, bottom ash, or particulate glass.
8. The method of claim 1, wherein the inorganic particulate
material has a particle size distribution ranging from about 0.0625
in. to below about 0.0017 in.
9. The method of claim 1, wherein the inorganic particulate
material contains less than about 0.5 wt % water.
10. The method of claim 1, wherein the polyol is mixed with the
catalyst prior to being mixed with the isocyanate.
11. The method of claim 1, wherein the polyol and the catalyst are
mixed prior to being introduced to the extruder.
12. The method of claim 1, wherein the polyol, the catalyst, and
the inorganic particulate material are mixed prior to being mixed
with the isocyanate.
13. The method of claim 1, wherein the molded material is a
building material.
14. The method of claim 13, wherein the building material is
lumber.
15. The method of claim 13, wherein the building material is
roofing.
16. The method of claim 13, wherein the building material is
siding.
17. The method of claim 1, wherein the molded material comprises a
relatively porous material and a relatively non-porous toughening
layer disposed on and adhered to the porous material.
18. The method of claim 1, further comprising allowing an
exothermic reaction to proceed without forced cooling except to
control a runaway exotherm.
19. The method of claim 1, wherein the outer surface of one of the
at least two first or second opposed endless belts is supported by
a rigid supporting surface.
20. The method of claim 19, wherein the at least two first opposed
endless belts are upper and lower-endless belts.
21. The method of claim 19, wherein the rigid supporting surface
comprises a slider bed or platen.
22. The method of claim 1, wherein the first opposed endless belts
or the second opposed endless belts, or both, are adjustable such
that the mold cavity can be varied.
23. The method of claim 1, wherein the mold cavity is at least
partly defined by the inner surfaces of two opposed profiled mold
belts disposed inside the at least two first opposed endless belts,
and having outer surfaces in contact with the inner surfaces of the
at least two second opposed endless belts.
24. The method of claim 23, wherein the profile mold belts form the
mixture into a shape having a cross-section at least approximately
corresponding to that of the mold cavity.
25. The method of claim 23, wherein the profile mold belts impart a
surface pattern to the moldable material.
26. A method of continuously forming a molded material comprising:
adding the ingredients of a highly filled composite mixture, to a
multi-zone extruder without adding heat, wherein the composite
mixture comprises: a monomeric or oligomeric poly or di-isocyanate;
a first polyol having a first molecular weight having a viscosity
in the range of about 480 cP to about 840 cP at 25.degree. C.; a
second polyol having a second molecular weight lower than the first
molecular weight having a viscosity in the range of about 480 cP to
about 840 cP at 25.degree. C.; a foaming agent; inorganic
particulate material comprising about 60 wt % to about 85 wt % of
the composite mixture, the particulate material comprising a
reinforcing filler; and a catalyst; adding the particulate material
to the mixture prior to forming; depositing the mixture through an
aperture to extrude or spray the material from the container to a
forming system, the forming system comprising: at least two first
opposed endless belts spaced apart a first distance, each having an
inner surface and an outer surface; a mold cavity defined at least
in part by a gap separating the inner surfaces of the at least two
first and second opposed endless belts; and a drive mechanism for
imparting motion to the opposed endless belts; precisely
maintaining the gap in the mold cavity substantially continuously
along the length of the mold cavity; supporting the first and
second opposed endless belts with a rigid substantially continuous
supporting surface along substantially the entire length of the
mold cavity to maintain substantially equal pressure on the
moldable material; and transferring the moldable material along the
mold cavity by longitudinal movement of the opposed endless belts;
removing the molded material from the mold cavity after sufficient
time has passed for the mixture to cure or harden into the molded
material, wherein the molded material comprises a density of at
least about 30 lb/ft.sup.3.
27. The method of claim 26, wherein the first and second polyol are
mixed prior to be introduced to the container.
28. The method of claim 26, wherein the first and second polyol are
mixed with the catalyst prior to being mixed with the
isocyanate.
29. The method of claim 26, wherein at least one of the first or
second polyols is mixed with the catalyst prior to being introduced
to the container.
30. The method of claim 26, wherein the first polyol, the second
polyol, the catalyst, and the inorganic particulate material are
mixed prior to being mixed with the isocyanate.
31. The method of claim 1, wherein the composition mixture has a
density in the range of about 20 lb/ft.sup.3 to about 90
lb/ft.sup.3.
32. The method of claim 1, wherein the poly- or di-isocyanate
comprises methylene diphenyl diisocyanate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/407,416, filed Apr. 20, 2006, currently
pending, which is a continuation of U.S. patent application Ser.
No. 10/764,012, filed Jan. 23, 2004, now U.S. Pat. No. 7,763,341,
issued Jul. 27, 2010; the complete disclosure of all of which are
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to composite compositions having
matrices of polymer networks and dispersed phases of particulate
and/or fibrous materials, which have excellent mechanical
properties, rendering them suitable for use in load bearing
applications, such as in building materials. The composites are
stable to weathering, can be molded and colored to desired
functional and aesthetic characteristics, and are environmentally
friendly, since they can make use of recycled particulate or
fibrous materials as the dispersed phase. The invention relates to
methods and systems for imparting desired shape and surface
characteristics to a moldable or pliable material as the material
cures or hardens. It is particularly applicable to the shaping and
embossing of thermosetting resin systems during curing, and can be
used to form these resin systems into a variety of products,
including synthetic lumber, roofing, and siding.
[0004] 2. Description of the Related Art
[0005] Polymeric composite materials that contain organic or
inorganic filler materials have become desirable for a variety of
uses because of their excellent mechanical properties, weathering
stability, and environmental friendliness.
[0006] These materials can be are relatively low density, due to
their foaming, or high density when unfoamed, but are extremely
strong, due to the reinforcing particles or fibers used throughout.
Their polymer content also gives them good toughness (i.e.,
resistance to brittle fracture), and good resistance to degradation
from weathering when they are exposed to the environment. This
combination of properties renders some polymeric composite
materials very desirable for use in building materials, such as
roofing materials, decorative or architectural products, outdoor
products, insulation panels, and the like.
[0007] In addition, the filler materials used need not be virgin
materials, and can desirably be recycled fibers or particulates
formed as waste or by-product from industrial processes. Polymeric
composites allow these materials to be advantageously reused,
rather than present disposal problems.
[0008] Filled composite polymeric materials have been described in
U.S. Pat. Nos. 5,302,634; 5,369,147; 5,548,315; and 5,604,260, the
contents of each of which is incorporated herein by reference.
However, the materials disclosed in these patents all use polyester
polyurethane resins that are formed as the reaction products of
unsaturated polyester polyols, saturated polyols, poly- or
di-isocyanates, and a reactive monomer, such as styrene. The number
of different reactants, and the complexity of the resulting process
chemistry, adds increased cost to the preparation of these
materials, both through added costs for materials inputs and
through added capital costs for additional process equipment.
[0009] A filled closed cell foam material is disclosed in U.S. Pat.
No. 4,661,533 (Stobby), but provides much lower densities than are
desirable for structural building products. Moreover, Stobby does
not disclose or suggest a composite material that is
"self-skinning," i.e., that forms a continuous skin on the surface
of the material that covers and protects the material underneath,
which is porous, and subject to visible scratching.
[0010] Various techniques exist for continuously forming a soft or
moldable material while it hardens or cures. For example, conveyor
belts can be used to provide continuous support and movement for
materials, and in some cases the belt faces may be contoured or
profiled to mold the surfaces of the material and to impart a
shape, feature, or surface appearance to the material. Two or more
such belts may be configured to operate with the belt surfaces
opposed and the material to be molded or shaped disposed between
them. These systems can form fairly detailed three-dimensional
products.
[0011] However, when such systems are used to form a foamed
product, the structure of the overall system must be sufficiently
strong to contain the pressure of the expanding foam. The longer
the forming system and the larger the cross-section of the product
to be formed, the greater the total force due to pressure and
friction that the system must contain and overcome. As a result, in
general, belt systems have not been thought to be suitable for
formation of resin systems that involve foaming of the polymer
matrix.
[0012] Forming systems have been developed to produce large
rectangular polyurethane foam buns; these systems typically contain
the foaming material within roller-supported films or sheets. The
many rollers used in these systems contain the increase in pressure
due to foaming, and also help to minimize system friction. However,
these systems are generally not able to mold detail or texture into
the product surface.
[0013] Pullers are two-belted machines designed to grip and pull an
extruded profile. As indicated above, conventional two-belt
systems, such as pullers that utilize thick profiled belts, may be
configured to continuously mold detail and texture into a product.
However, these forming systems typically require profiled belts
with relatively thick sidewall cross sections. The thick sidewalls
minimize deflection of the unsupported sides of the mold-belt,
thereby maintaining the intended product shape, and limiting
extrusion of material through the resultant gap between belts. The
thickness of the product formed by a conventional two-belt system
is thus limited in practice by the thickness and width of the
profiled mold-belts. Thicker belts needed to form products with
deeper profiles require larger diameter end pulleys in order to
prevent excessive bending, stretching, and premature breakage of
the mold material.
[0014] In addition, most pullers are relatively short (6 feet or
less). These short forming systems tend to require slower
production speeds, allowing the product enough time in-mold to
harden sufficiently before exiting the forming unit. Longer
two-belt machines can be made, but in order to manage belt/bed
friction these longer systems typically require the use of rollers
to support the back of the profiled belts. Roller supported
mold-belts tend to allow the mold faces to separate between rollers
where the belts are unsupported, allowing material to leak between
belt faces.
[0015] To continuously mold larger foamed cross-sections and to
impart irregular shape or surface detail to the product, table-top
conveyors are frequently used. Table-top conveyors use segmented
metal mold sections attached to a metal chain-type conveyor. Two
table-top conveyors are typically arranged face-to-face when used
in this type of application, providing a rigid continuous mold.
Preventing material from migrating into the Joints between adjacent
mold sections can be problematic for this type of forming system
and may required the use of plastic films disposed between the mold
and material to prevent leaks. In addition, such table-top conveyor
systems are complex and costly.
[0016] Because of the various difficulties and deficiencies
described above for existing forming systems, there remains a need
in the art for a low cost forming system that can shape a curing
polymer system, and in particular a foaming polymer system, without
leaking. There is a need for such a system that can impart surface
patterns and designs to the curing material, and that has
sufficiently low friction and thickness that it can be practically
made long enough to allow sufficient curing time in the system.
SUMMARY OF THE INVENTION
[0017] It has been found, however, that a highly filled, foamed or
unfoamed composite polymeric material having good mechanical
properties can be obtained without the need for all of the
components required in the patents cited above. This results in a
substantial decrease in cost, because of decreased materials cost,
and because of decreased complexity of the process chemistry,
leading to decreased capital investment In process equipment.
[0018] In one embodiment, the invention relates to composite
compositions having a matrix of polymer networks and dispersed
phases of particulate or fibrous materials. The polymer matrix
contains a polyurethane network formed by the reaction of a poly-
or di-isocyanate and one or more saturated polyether or polyester
polyols, and an optional polyisocyanurate network formed by the
reaction of optionally added water and isocyanate. The matrix is
filled with a particulate phase, which can be selected from one or
more of a variety of components, such as fly ash particles, axially
oriented fibers, fabrics, chopped random fibers, mineral fibers,
ground waste glass, granite dust, or other solid waste materials.
The addition of water can also serve to provide a blowing agent to
the reaction mixture, resulting in a foamed structure, if such is
desired.
[0019] The composite material of the invention is advantageously
used as structural building material, and in particular as
synthetic lumber, for several reasons. First, it has the desired
density, even when foamed, to provide structural stability and
strength. Second, the composition of the material can be easily
tuned to modify its properties by, e.g., adding oriented fibers to
increase flexural stiffness, or by adding pigment or dyes to hide
the effects of scratches. This can be done even after the material
has been extruded. Third, the material is self-skinning, forming a
tough, slightly porous layer that covers and protects the more'
porous material beneath. This tough, continuous, highly adherent
skin provides excellent water and scratch resistance. In addition,
as the skin is forming, an ornamental pattern (e.g., a simulated
wood grain) can be impressed on it, increasing the commercial
acceptability of products made from the composite.
[0020] In a more specific embodiment, the invention relates to a
polymer matrix composite material, comprising:
[0021] (1) a polyurethane formed by reaction of [0022] (a) one or
more monomeric or oligomeric poly- or di-isocyanates; [0023] (b) a
first polyether polyol having a first molecular weight; and [0024]
(c) an optional second polyether polyol having a second molecular
weight lower than the first molecular weight; and
[0025] (2) optionally, a polyisocyanurate formed by reaction of a
monomenc or oligomeric poly- or di-isocyanate with water or other
blowing agents;
[0026] (3) a particulate inorganic filler.
[0027] As indicated above, the polymer matrix composite material of
the invention can have a variety of different uses. However, it is
particularly suitable in structural applications, and in particular
as a synthetic lumber. Accordingly, another specific embodiment of
the invention relates to a synthetic lumber, comprising the polymer
matrix composite material described above, and having a relatively
porous material and a relatively non-porous toughening layer
disposed on and adhered to the porous material.
[0028] It has been found that the process used to manufacture the
polymer matrix composite material and the synthetic lumber formed
therefrom can have an important impact on the appearance and
properties of the resulting material, and thus on its commercial
acceptability. Accordingly, another particular embodiment of the
invention relates to a method of producing a polymer matrix
composite, by:
[0029] (1) mixing a first polyether polyol having a first molecular
weight and a second polyether polyol having a second molecular
weight higher than the first molecular weight with a catalyst,
optional water, and optional surfactant;
[0030] (2) optionally introducing reinforcing fibrous materials
into the mixture;
[0031] (3) introducing inorganic filler into the mixture;
[0032] (4) introducing poly- or di-isocyanate into the mixture;
and
[0033] (5) allowing the exothermic reaction to proceed without
forced cooling except to control runaway exotherm.
[0034] The materials of the invention, and the process for their
preparation, are environmentally friendly. They provide a mechanism
for reuse of particulate waste in a higher valued use, as described
above. In addition, the process for making them optionally uses
water in the formation of polyisocyanurate, which releases carbon
dioxide as the blowing agent. The process thus avoids the use of
environmentally harmful blowing agents, such as halogenated
hydrocarbons.
[0035] The invention disclosed in this application is a new type of
forming system utilizing up to six belts. The forming system is
uniquely suited to the continuous forming of a range of product
sizes with intricate molded-in detail. Material that may be formed
using the described system include but are not limited to:
thermoplastic and thermoset plastic compounds, highly-filled
plastic compounds, elastomers, ceramic materials, and cementitious
materials. The system is particularly suited to the forming of
foamed materials. The material to be formed may be poured, dropped,
extruded, spread, or sprayed onto or into the forming system.
[0036] In one embodiment, the invention relates to a system for
providing shape, surface features, or both, to a moldable material,
the system having:
[0037] at least two first opposed flat endless belts disposed a
first distance apart from each other, each having an inner surface
and an outer surface;
[0038] at least two second opposed flat endless belts disposed
substantially orthogonal to the first two opposed endless belts and
a second distance apart from each other, and each having an inner
surface and an outer surface;
[0039] a mold cavity defined at least in part by the inner surfaces
of at least two of the opposed flat endless belts; and
[0040] a drive mechanism for imparting motion to at least two of
the opposed flat endless belts.
[0041] In a more particular embodiment, the invention relates to a
forming system having 4 flat belted conveyors configured so as to
define and enclose the top, bottom, and sides of a 4-sided,
open-ended channel, and an additional two profiled mold-belts that
are configured to fit snugly, face-to-face within the channel
provided by the surrounding flat belts. All belts are endless and
supported by pulleys at the ends of their respective beds so as to
allow each belt to travel continuously about its fixed path.
[0042] In another embodiment, the invention relates to a method of
continuously forming a moldable material to have a desired shape or
surface feature or both, comprising:
[0043] introducing the moldable material into an end of a mold
cavity formed at least in part by the inner surfaces of two
substantially orthogonal sets of opposed flat belts;
[0044] exerting pressure on the moldable material through the
opposed flat belts;
[0045] transferring the moldable material along the mold cavity by
longitudinal movement of the belts;
[0046] after sufficient time for the material to cure or harden
into the molded configuration and thereby form molded material,
removing the molded material from the mold cavity.
[0047] The system and method are versatile, permitting the
production of a range of product sizes and profiles using the same
machine. In an exemplary embodiment, the system and method provide
for the continuous forming of synthetic lumber, roofing tiles,
molded trim profiles, siding or other building products from
heavily-filled, foamed thermoset plastic compounds and/or foamed
ceramic compounds with organic binders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] FIG. 1A is a top plan view, FIG. 1B is a side plan view, and
FIG. 1C is an end plan view of one embodiment of a system of the
invention.
[0049] FIG. 2 is a partially expanded isometric view of one end of
the system illustrated in FIG. 1.
[0050] FIG. 3A is an end plan view of one embodiment of the system
of the invention. FIG. 3B is an exploded sectional view of the
system of FIG. 3A.
[0051] FIG. 4 is a sectional view of a profile mold belt used in
certain embodiments of the system of the invention.
[0052] FIG. 5 is a partial sectional, partial end plan view of a
four belt configuration of the system of the invention.
[0053] FIG. 6 is a sectional view of a configuration of the system
of the invention using drive belts and supporting the sides of the
mold belts with pressurized air.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0054] As described above, one embodiment of the invention relates
to a composite composition containing a polymeric matrix phase and
a dispersed inorganic particulate phase, and which can contain
other materials, such as reinforcing fibers, pigments and dyes, and
the like. One of the desirable properties of the material is its
self-skinning nature.
[0055] The polymeric phase desirably contains at least a
polyurethane, generally considered to be a 2-part or thermosetting
polyurethane. The polyurethane is formed by reacting a poly- or
di-isocyanate (hereinafter "isocyanate"), particularly an aromatic
diisocyanate, more particularly, a methylene diphenyl diisocyanate
(MDI), with one or more polyether polyols, described in more detail
below.
[0056] The MDI used in the invention can be MDI monomer, MDI
oligomer, or a mixture thereof. The particular MDI used can be
selected based on the desired overall properties, such as the
amount of foaming, strength of bonding to the inorganic
particulates, wetting of the inorganic particulates in the reaction
mixture, strength of the resulting composite material, and
stiffness (elastic modulus). Although toluene diisocyanate can be
used, MDI is generally preferable due to its lower volatility and
lower toxicity. Other factors that influence the particular MDI or
MDI mixture used in the invention are viscosity (a low viscosity is
desirable from an ease of handling standpoint), cost, volatility,
reactivity, and content of 2,4 isomer. Color may be a significant
factor for some applications, but does not generally affect
selection of an MDI for preparing synthetic lumber.
[0057] Light stability is also not a particular concern for
selecting MDI for use in the composite of the invention. In fact,
the composite of the invention allows the use of isocyanate
mixtures not generally regarded as suitable for outdoor use,
because of their limited light stability. When used in the
composite of the invention, these materials surprisingly exhibit
excellent light stability, with little or no yellowing or chalking.
Since isocyanate mixtures normally regarded as suitable for outdoor
use (generally aliphatic isocyanates) are considerably more
expensive than those used in this invention, the ability of the
invention to use MDI mixtures represents a significant cost
advantage.
[0058] Suitable MDI compositions for use in the invention include
those having viscosities ranging from about 25 to about 200 cp at
25.degree. C. and NCO contents ranging from about 30% to about 35%.
Generally, isocyanates are used that provide at least 1 equivalent
NCO group to 1 equivalent OH group from the polyols, desirably with
about 5% to about 10% excess NCO groups. Suitable isocyanates
include Bayer MRS-4, Bayer MR Light, Dow PAPI 27, Bayer MR5, Bayer
MRS-2, and Rubinate 9415.
[0059] As indicated above, the isocyanate used in the invention is
reacted with one or more polyols. In general, the ratio of
isocyanate to polyol, based on equivalent weights (OH groups for
polyols and NCO groups for isocyanates) is generally in the range
of about 0.5:1 to about 1.5:1, more particularly from about 0.8:1
to about 1.1:1, Ratios in these ranges provide good foaming and
bonding to inorganic particulates, and yields low water pickup,
fiber bonding, heat distortion resistance, and creep resistance
properties. However, precise selection of the desired ratio will be
affected by the amount of water in the system, including water
added per se as a foaming agent, and water introduced with other
components as an "impurity."
[0060] The polyol or polyols used may be single monomers,
oligomers, or blends. Mixtures of polyols can be used to influence
or control the properties of the resulting polymer network. For
example, mixtures of two polyols, one a low molecular weight,
rubbery rigid (relative to the second) polyol and the other a
higher molecular weight, more rubbery (relative to the first)
polyol. The amount of rigid polyol is carefully controlled in order
to avoid making the composite too brittle. An amount (a ratio of
flexible polyol to rigid polyol of between about 5 wt % and about
20 wt %, more particularly around 15 wt %, based on the total
weight of the flexible and rigid polyols being 100 wt %, has
generally been found to be suitable. It is generally desirable to
use polyols in liquid form, and generally in the lowest viscosity
liquid form available, as these can be more easily mixed with the
inorganic particulate material. So-called "EO" tipped polyols can
be used; however their use is generally avoided where it is desired
to avoid "frosting" of the polymer material when exposed to
water.
[0061] In general, desirable polyols include polyether polyols,
such as MULTRANOL (Bayer), including MULTRANOL 3400 or MULTRANOL
4035, ethylene glycol, diethylene glycol, triethylene glycol,
dipropylene glycol, glycerol, 2-butyn-1,4-diol, neopentyl glycol,
1,2-propanediol, pentaerythritol, mannitol, 1,6-hexanediol,
1,3-buytylene glycol, hydrogenated bisphenol A,
polytetramethyleneglycolethers, polythioethers, and other di- and
multi-functional polyethers and polyester polyethers, and mixtures
thereof. The polyols need not be miscible, but should not cause
compatibility problems in the polymeric composite.
[0062] As indicated above, the composite of the invention can
desirably be prepared by mixing the polyols together (if multiple
polyols are used), and then mixing them with various additives,
such as catalysts, surfactants, and foaming agent, and then adding
the inorganic particulate phase, then any reinforcing fiber, and
finally the isocyanate.
[0063] One or more catalysts are generally added to control the
curing time of the polymer matrix (upon addition of the
isocyanate), and these may be selected from among those known to
initiate reaction between isocyanates and polyols, such as
amine-containing catalysts, such as DABCO and
tetramethylbutanediamine, tin-, mercury- and bismuth-containing
catalysts. To increase uniformity and rapidity of cure, it may be
desirable to add multiple catalysts, including a catalyst that
provides overall curing via gelation, and another that provides
rapid surface curing to form a skin and eliminate tackiness. For
example, a liquid mixture of 1 part tin-containing catalyst to 10
parts amine-containing catalyst can be added in an amount greater
than 0 wt % and below about 0.10 wt % (based on the total reaction
mixture) or less, depending on the length of curing time desired.
Too much catalyst can result in overcuring, which could cause
buildup of cured material on the processing equipment, or too stiff
a material which cannot be properly shaped, or scorching; in severe
cases, this can lead to unsaleable product or fire. Curing times
generally range from about 5 seconds to about 2 hours.
[0064] A surfactant may optionally be added to the polyol mixture
to function as a wetting agent and assist in mixing of the
inorganic particulate material. The surfactant also stabilizes
bubbles formed during foaming (if a foamed product is desired) and
passivates the surface of the inorganic particulates, so that the
polymeric matrix covers and bonds to a higher surface area.
Surfactants can be used in amounts below about 0.5 wt %, desirably
about 0.3 wt %, based on the total weight of the mixture. Excess
amount of surfactant can lead to excess water absorption, which can
lead to freeze/thaw damage to the composite material. Silicone
surfactants have been found to be suitable for use in the
invention. Examples include DC-197 and DC-193 (silicone-based, Air
Products), and other nonpolar and polar (anionic and cationic)
products.
[0065] Foaming agent may also be added to the polyol mixture if a
foamed product is desired. While these may include organic blowing
agents, such as halogenated hydrocarbons, hexanes, and other
materials that vaporize when heated by the polyolisocyanate
reaction, it has been found that water is much less expensive, and
reacts with isocyanate to yield CO.sub.2, which is inert, safe, and
need not be scrubbed from the process. Equally as important,
CO.sub.2 provides the type of polyurethane cells desirable in a
foamed product (i.e., mostly open, but some closed cells), is
highly compatible with the use of most inorganic particulate
fillers, particularly at high filler levels, and is compatible with
the use of reinforcing fibers. Other foaming agents will not
produce the same foam structure as is obtained with water.
[0066] If water is not added to the composition, some foaming may
still occur due to the presence of small quantities of water
(around 0.2 wt %, based on the total weight of the reaction
mixture) introduced with the other components as an "impurity." On
the other hand, excessive foaming resulting from the addition of
too much water (either directly or through the introduction of
"wet" reactants or inorganic particulate materials) can be
controlled by addition of an absorbent, such as UOP "T" powder.
[0067] The amount of water present in the system will have an
important effect on the density of the resulting composite
material. This amount generally ranges from about 0.10 wt % to
about 0.40 wt %, based on the weight of polyol added, for composite
densities ranging from about 20 lb/ft.sup.3 to about 90
lb/ft.sup.3.
[0068] Reinforcing fibers can also be introduced into the polyol
mixture prior to introduction of the isocyanate. These can include
fibers per se, such as chopped fiberglass, or fabrics or portions
of fabrics, such as rovings or linear tows, or combinations of
these. Typically, the reinforcing fibers range from about 0.125 in.
to about 1 in, more particularly from about 0.25 in to about 0.5
in. The reinforcing fibers give the material added strength
(flexural, tensile, and compressive), increase its stiffness, and
provide increased toughness (impact strength or resistance to
brittle fracture). Fabrics, rovings, or tows increase flexural
stiffness and creep resistance. The inclusion of the particular
polyurethane networks of the invention, together with the optional
surfactants, and the inorganic particulate sizes used make the
composite of the invention particularly and surprisingly well
suited for inclusion of reinforcing fibers in foamed material,
which normally would be expected to rupture or distort the foam
bubbles and decrease the strength of the composite system.
[0069] In addition to inclusion of reinforcing fibers into the
polyol mixture prior to polymerization, oriented axial fibers can
also be introduced into the composite after extrusion, as the
polymer exits the extruder and prior to any molding. The fibers
(e.g., glass strings) can desirably be wetted with a mixture of
polyol (typically a higher molecular weight, rigid polyol) and
isocyanate, but without catalyst or with a slow cure catalyst, or
with other rigid or thermosetting resins, such as epoxies. This
allows the wetted fiber to be incorporated into the composite
before the newly added materials can cure, and allows this curing
to be driven by the exotherm of the already curing polymer in the
bulk material.
[0070] Whether added before or after polymerization and extrusion,
the composite material of the invention contains a polymeric matrix
phase that is strongly bonded to the dispersed reinforcing fibers,
increasing the strength and stiffness of the resulting material.
This enables the material to be used as a structural synthetic
lumber, even at relatively low densities (e.g., about 20 to about
60 lb/ft.sup.3).
[0071] Pigment or dye can be added to the polyol mixture or can be
added at other points in the process. The pigment is optional, but
can help make the composite material more commercially acceptable,
more distinctive, and help to hide any scratches that might form in
the surface of the material. Typical examples of pigments include
iron oxide, typically added in amounts ranging from about 2 wt % to
about 7 wt %, based on the total weight of the reaction
mixture.
[0072] The inorganic particulate phase is an important feature of
the invention, and is typically present in amounts ranging between
about 45 wt % to about 85 wt % of the total composition. Increasing
the proportion of inorganic particulate can lead to increased
difficulty in mixing, making the inclusion of a surfactant more
desirable. The inorganic particulate material should have less than
about 0.5 wt % water (based on the weight of the particulate
material) in order to avoid excessive or uncontrolled foaming.
[0073] It is generally desirable to use particulate materials with
a broad particle size distribution, because this provides better
particulate packing, leading to increased density and decreased
resin level per unit weight of composite. Since the inorganic
particulate is typically some form of waste or scrap material, this
leads to decreased raw material cost as well. Particles having size
distributions ranging from about 0.0625 in (or about 10 mesh) to
below about 0.0017 in (or about 325 mesh) have been found to be
particularly suitable.
[0074] Suitable inorganic particulates can include ground glass
particles, fly ash, bottom ash, sand, granite dust, and the like,
as well as mixtures of these. Fly ash is desirable because it is
uniform in consistency, contains some carbon (which can provide
some desirable weathering properties to the product due to the
inclusion of fine carbon particles which are known to provide
weathering protection to plastics, and the effect of opaque ash
particles which block UV light, and contains some metallic species,
such as metal oxides, which are believed to provide additional
catalysis of the polymerization reactions. Ground glass (such as
window or bottle glass) absorbs less resin, decreasing the cost of
the composite. A 1:1 mixture of coal fly ash and bottom ash has
also been found to be suitable as the inorganic particulate
composition. In general, fly ash having very low bulk density
(e.g., less than about 40 lb/ft.sup.3) and/or high carbon contents
(e.g., around 20 wt % or higher) are less suitable, since they are
more difficult to incorporate into the resin system, and may
require additional inorganic fillers that have much less carbon,
such as foundry sand, to be added. Fly ash produced by coal-fueled
power plants, including Houston Lighting and Power power plants,
fly and bottom ash from Southern California Edison plants (Navajo
or Mohave), fly ash from Scottish Power/Jim Bridger power plant in
Wyoming, and fly ash from Central Hudson Power plant have been
found to be suitable for use in the invention.
[0075] The process for producing the composite material may be
operated in a batch, semi batch, or continuous manner. Mixing may
be conducted using conventional mixers, such as Banbury type
mixers, stirred tanks, and the like, or may be conducted in an
extruder, such as a twin screw, co-rotating extruder. When an
extruder is used, additional heating is generally not necessary,
especially if liquid polyols are used. In addition, forced cooling
is not generally required, except for minimal cooling to control
excessive or runaway exotherms.
[0076] For example, a multi-zone extruder can be used, with polyols
and additives introduced into the first zone, inorganic
particulates introduced in the second zone, and chopped fibers,
isocyanate, and pigments introduced in the fifth zone. A twin
screw, co-rotating, extruder (e.g. 100 mm diameter, although the
diameter can be varied substantially) can be used, with only water
cooling (to maintain room temperature), and without extruder vacuum
(except for ash dust). Liquid materials can be pumped into the
extruder, while solids can be added by suitable hopper/screw feeder
arrangements. Internal pressure build up in such an exemplary
arrangement is not significant.
[0077] Although gelation occurs essentially immediately, complete
curing can take as long as 48 hours, and it is therefore desirable
to wait at least that long before assessing the mechanical
properties of the composite, in order to allow both the composition
and the properties to stabilize.
[0078] As explained above, the composite material of the invention
is advantageously used in structural products, including synthetic
lumber. The synthetic lumber may be formed in a batch, semibatch,
or continuous fashion. For example, in continuous operation,
polymerized (and polymerizing) material leaving the extruder (after
optional incorporation of post-extruder fibers, tows, or rovings)
is supplied to a forming system, which provides dimensional
constraint to the material, and can be used to pattern the surfaces
of the resulting synthetic lumber with simulated woodgrain or other
designs, in order to make the material more commercially desirable.
For example, a conveyor belt system comprising 2, 4, or 6 belts
made from a flexible resin having wood grain or other design molded
therein can be used. One such suitable system is described in
copending U.S. patent application Ser. No. 10/764,013, filed on
Jan. 23, 2004, the entire contents of which are incorporated herein
by reference. Desirably, the belts are formed from a self-releasing
rubber or elastomeric material so that it will not adhere to the
polymer composite. Suitable belt materials include silicone rubber,
oil impregnated polyurethane, or synthetic or natural rubbers, if
necessary coated with a release agent, such as waxes, silicones, or
fluoropolymers.
[0079] For clarity of understanding, the invention will be
described herein with respect to a single apparatus. It should be
understood, however, that the invention is not so limited, and the
system and method of the invention may involve two or more such
systems operated in series or in parallel, and that a single system
may contain multiple sets of belts, again operated in series or in
parallel.
Flat-Belted Conveyor Channel
[0080] Each set of opposed flat belt conveyors are oriented so that
their bearing surfaces face each other. One set of opposed flat
belts can be thought of as "upper" and "lower" belts, although
these descriptors are not limiting, nor do they require that the
two opposed belts be horizontal. In practice, however, one set of
opposed belts (the upper and lower belts) will be substantially
horizontal. These belts can define the upper and lower surfaces of
a mold cavity (when the device is operated in four-belt mode), or
may provide support and drive surfaces for a set of opposed profile
mold belts (when the device is operated in six-belt mode). The
remaining set of opposed flat belts are disposed substantially
orthogonal to the first set. As used herein, the term
"substantially orthogonal" means close to perpendicular, but
allowing for some deviation from 90.degree. resulting from
adjustment of the device, variations from level in the
manufacturing floor, etc. This substantially orthogonal arrangement
is accomplished in two basic configurations.
[0081] The first exemplary configuration involves disposing the
flat bearing surfaces of the second set of belts along the sides of
the space formed by the first set of belts, thereby forming an
open-ended mold cavity that is enclosed by flat belts, and having a
length corresponding to the length of the "side" belts. This
configuration is illustrated in FIG. 5. FIG. 1A provides a top
view, FIG. 1B a side view, and FIG. 1C an end view, of a system 2
having upper flat belt 4, lower flat belt 4'' upper profile mold
belt 6, lower profile mold belt 6', and side belts 8 and 8'. These
side belts extend longitudinally approximately the same distance as
the upper and lower flat belts, providing a mold cavity that is
supported from the side over virtually the entire length of the
profile mold belts. Profile mold belts 6 and 6' are maintained in
tension by tensioning rolls 10. Flat belts 4 and 4' are powered by
driven rollers 12 and 12'.
[0082] The arrangement of belts and the corresponding rollers for
this exemplary configuration can be seen in more detail in FIG. 2,
which is a partially expanded view, wherein the upper flat belt 4,
upper profile mold belt 6, and corresponding supports and rollers
10 and 12, have been lifted away from the remainder of the system
for ease of visualization. Side belts 8, 8' are supported by side
belt supports 14 and 14', and can run on side belt support rollers
16, 16'. These side belt support rollers are powered, or unpowered,
as illustrated in FIG. 2. In addition, upper and lower flat belts 4
and 4' are supported by rigid supporting surfaces, such as platens
18, 18'.
[0083] As mentioned above, each flat belt is supported by a
slider-bed or platen comprised of a rigid metal plate or other
rigid supporting surface, if the length of the belt makes such
support necessary or desirable. Generally, in order to provide
sufficient curing time for filled polyurethane foams, a support
surface is desirable but not required. The surface of the
slider-bed in one embodiment has a slippery coating or bed-plate
material attached or bonded to it (for example, ultra-high
molecular weight polyethylene, PTFE, or other fluoropolymer). Also,
the belt has a slippery backing material (for example, ultra-high
molecular weight polyethylene, PTFE or other fluoropolymer) to
reduce friction between the bed and moving belt in an exemplary
embodiment.
[0084] To further reduce friction and enhance cooling of the belts
and conveyor machinery, the slider-beds and attached slippery
surface material of a conveyor has a plurality of relatively small
holes drilled through the surface. These holes are in fluid
communication with a source of compressed gas, such as air. As an
example, a plenum chamber is provided behind each slider bed, which
is then connected to a source of pressurized air. Pressurized air
fed into each plenum passes through the holes in the bed, and
provides a layer of air between the bed and the adjacent belt. This
air film provides lubrication between the bed and adjacent belt as
shown in FIG. 2, where compressed air is supplied to the plenums
through openings 20, 20'. The air fed into the plenums has a
pressure higher than the foaming pressure of the product to be
useful in reducing operating friction. In one embodiment, shop air
or high-pressure blowers are used to provide the pressurized air to
feed the plenums.
[0085] In a more particular exemplary embodiment, shown in FIG. 6,
air supply plenums are also used to provide support to the sides of
the mold belts, either directly (shown) or through side belts (not
shown). In FIG. 6, flat belts 4 and 4' are supported by upper and
lower air supply plenums 32 and 32', respectively. Areas of contact
between the belts and the plenums are prepared from or coated with
a low-friction substance, such as PTFE, or are lubricated to lower
the friction between the belts and the supporting surfaces.
Pressurized air 34 is supplied to these plenums through openings
36, 36', and exits the plenums through openings 38, 38', where it
flows under and supports flat belts 4, 4', which in turn support
the upper and lower surfaces of profile mold belts 6, 6'. In
addition, pressurized air 40 enters side plenums 42, 42' through
openings 44, 44'. The air leaves these side plenums through opening
46, 46', and flows against and supports the sides of profile mold
belts 6, 6'. This support can result either from the air flow
impinging directly on the sides of the mold belts, or from air flow
impinging on the surfaces of side belts that in turn press against
the sides of the profile mold belts. The profile mold belts, in
turn, provide support to the material being formed, 48.
[0086] The flat-belts are powered and driven at matching speeds
with respect to one another. The matched speed are achieved, in one
embodiment, by mechanical linkage between the conveyors or by
electronic gearing of the respective motors. Alternatively, as
illustrated in FIGS. 1 and 2, only two flat belts are driven (for
example, the two opposing belts with greater contact area, which
are typically the upper and lower belts) with the remaining two
flat belts (for example, the side belts) un-driven and idling. The
flat-belts form a relatively rigid moving channel through which
contoured mold-belts and/or forming product is moved and
contained.
[0087] The driven flat-belts utilize known driven roller
technologies, including center-drive pulley mechanisms, whereby
more than 180.degree. of contact is maintained between each
conveyor's driving pulley and belt, increasing the amount of force
that may be delivered to the belt.
[0088] In another exemplary configuration, the side flat belts are
disposed substantially orthogonal relative to the upper and lower
flat belts such that their bearing surfaces face each other, and
are in a plane substantially perpendicular to the plane of the
bearing surfaces of the upper and lower belts, as illustrated in
FIG. 3. FIG. 3A is an end view with the corresponding drive and
support apparatus removed for ease of viewing. FIG. 3A shows side
flat belts 8 and 8' disposed between upper flat belt 4 and lower
flat belt 4'. An expanded sectional view of this exemplary
configuration is provided in FIG. 3B. The frames 22 and 22'
supporting the side belts are restrained in such a way as to allow
the position of the side flat belts to be adjusted laterally
providing the desired degree of pressure against the sides of
profile mold belts 6 and 6' or to accommodate mold belts of
alternate widths. This configuration provides a relatively short,
but highly contained mold cavity 24.
Mold-Belts
[0089] The contoured mold-belts are relatively thick belts with a
rubbery face material attached to a fiber-reinforced backing or
carcass as shown in FIG. 4. The profile mold belt 6' is constructed
to contain an inner surface 25, that defines part of mold cavity
24. It also has side surfaces 26, which contact side flat belts 8,
8', and outer surface 30, which contacts the inner surface of flat
belt 4'. The fiber-reinforcement 28 in the backing of the belts
will provide the strength and rigidity in the belt while the face
material has the profile, surface features, and texture that is
molded into the product. The desired mold profile, surface
features, and texture are machined, cut, bonded, and/or cast into
the surface of the mold-belts. The mold cavity created by the mold
belts has a constant, irregular, and/or segmented cross section.
Multiple cavities can be incorporated into a single set of mold
belts. Suitable mold surface materials include, but are not
restricted to Nitrile, Neoprene, polyurethane, silicone elastomers,
and combinations thereof. Suitable fibers for reinforcing the
profile mold belt include cotton, aramid, polyester, nylon, and
combinations thereof.
[0090] Each profile mold-belt travels beyond the ends of the
surrounding flat-belt conveyors to a separate set of large pulleys
or rollers that maintain tension and the relative position of each
belt. In one embodiment, the mold-belts are un-powered, functioning
as idlers or slave belts to the powered flat belts behind them. In
another embodiment, the mold belts are separately powered.
[0091] The temperature of the mold belts can be adjusted during
production in the event that additional heat is needed or surplus
heat is to be removed. If the temperature of the belt surface is
adjusted, temperature controlled air is blown onto the belt
surfaces as the belts exit the flat-belted conveyor enclosure and
follow their return path to the entrance of the forming machine. In
one embodiment, infrared or other radiant heaters are used to
increase the temperature of the mold surface. In another
embodiment, temperature controlled air or other fluid is routed
through the conveyor frames to maintain predetermined process
temperatures.
Orientation
[0092] As described above, the exemplary orientation of the forming
system is for the contact surface between mold-belts to be
horizontal. The gap between the upper and lower flat-belted
conveyors (those conveyors adjacent to the backs of the
mold-belts), can be precisely maintained such that the pair of
mold-belts pass between them without being allowed to separate
(presenting a gap to the molding material) and without excessively
compressing the mold-belt shoulders or side walls. In the exemplary
embodiment, the upper conveyor is removable while not in operation
in order to permit replacement of the mold belts.
Side Conveyors
[0093] The flat-belted conveyors adjacent to the sides of the
profile mold belts provide structural support for the sides of the
mold cavity, resist any deflection of the sides due to foaming
pressure, and maintain alignment of the mold-belts. These
side-supporting conveyors permit the use of thinner mold-belt
sidewalls, which reduces the cost and mass of the mold-belts. The
use of these side-supporting conveyors also permits the molding of
deeper product cross sections without requiring excessive mold-belt
widths.
System Versatility
[0094] An exemplary configuration for the flat-belted conveyors is
for the top and bottom conveyors to be wide, with the side
conveyors sized to fit between the belts of the upper and lower
conveyors in such a way that the surface of the upper and lower
(wide) belts approach or make contact with the edges of the side
belts. The frames, pulleys, and slider-beds of the side conveyors
are slightly narrower than their respective belts to avoid contact
with the upper and lower belts. A cross section of this exemplary
configuration is shown in FIG. 3B as described above. With this
orientation, the gap between the side conveyors is adjustable in
order to accommodate wider or narrower pairs of mold-belts. This
configuration permits a range of product widths to be produced by
the same forming machine. Only the mold-belt set is replaced in
order to produce product of a different width.
[0095] To further increase the versatility of the forming machine,
the side conveyor belts, pulleys, and slider beds are replaced with
taller or shorter components and the gap between upper and lower
conveyors adjusted accordingly. This feature permits the forming
machine to accommodate mold-belts of various depths to produce
thicker or thinner cross sections.
Four-Belt Mode
[0096] The specific exemplary embodiments described above with
respect to the drawings generally relate to configuration of the
system in "six belt mode." In other words, an upper and lower flat
belt, two side flat belts, and an upper and lower profile mold
belt. The mold belts permit surface details, corner radii,
irregular thicknesses, and deeper surface texture to be molded into
the continuously formed product. However, for rectangular or square
cross-sectioned products that do not require corner radii, deep
texture, or localized features, the forming system is used without
mold-belts, and operated in "four belt mode." In this exemplary
operating configuration the four flat belts make direct contact
with the moldable product and permits the product to form within
the flat-sided cavity. When the forming system is used in this
configuration it is important that the upper and lower belts
maintain contact with the edges of the side belts to prevent
seepage of the material between adjacent belts. In order to produce
thicker or thinner products in "four belt mode" the side flat
belts, adjacent slider beds, and side belt pulleys are replaced
with components in the target thickness. The gap between side belts
is adjusted to accommodate the target width. Using this approach a
large variety of four-sided cross-sections can be produced by the
same machine without the added cost of dedicated mold-belts.
[0097] The four belt configuration is illustrated in FIG. 5. The
sectional portion of the drawing shows that the mold cavity 24 is
formed by the surfaces of upper and lower flat belts 4, 4' and the
surfaces of side belts 8, 8'.
Fabrication
[0098] The forming system structure may be fabricated using metal
materials and typical metal forming and fabricating methods such as
welding, bending, machining, and mechanical assembly.
[0099] The forming system is used to form a wide variety of
moldable materials, and has been found to be particularly suitable
for forming synthetic lumber.
[0100] Representative suitable compositional ranges for synthetic
lumber, in percent based on the total composite composition, are
provided below:
TABLE-US-00001 Rigid polyol about 6 to about 18 wt % Flexible
polyol 0 to about 10 wt % Surfactant about 0.2 to about 0.5 wt %
Skin forming catalyst about 0.002 to about 0.01 wt % Gelation
catalyst about 0.02 to about 0.1 wt % Water 0 to about 0.5 wt %
Chopped fiberglass 0 to about 10 wt % Pigments 0 to about 6 wt %
Inorganic particulates about 60 to about 85 wt % Isocyanate about 6
to about 20 wt % Axial tows 0 to about 6 wt %
[0101] The invention can be further understood by reference to the
following non-limiting examples.
Example 1
[0102] A polymer composite composition was prepared by introducing
9.5 wt % rigid polyol (MULTRANOL 4035, Bayer), 0.3 wt % rubber
polyol (ARCOL LG-56, Bayer), 0.3 wt % surfactant/wetting agent
(DC-197, Air Products), 0.005 wt % film forming organic tin
catalyst (UL-28/22, Air Products), 0.03 wt % amine gelation
catalyst (33LV, Air Products), and 0.05 wt % water as foaming agent
to the drive end of a 100 mm diameter twin screw co-rotating
extruder with water cooling to maintain room temperature. At a
point around 60% of the length of the extruder, 4.2 wt % chopped
glass fibers (Owens Corning) with 114 to 112 inch lengths were
added, along with 4.0 wt % brown pigment (Interstar), 74 wt % fly
ash (ISG), and 9.6 wt % isocyanate (MONDUR MR Light, Bayer). The
extruder was operated at room temperature (75.degree. F.), at 200
rpm for one hour. Following extrusion, 0.4 wt % of a resin mixture
of rubbery polyol (ARCOL LG-56, Bayer), and isocyanate (MONDUR MR
Light, Bayer) were added to the surface of the extruded material to
provide a bonding adhesive for glass tows. The glass tows (Owens
Corning) 1/4 to 1/2 inch length were added in an amount of around 2
wt % to provide added rigidity, and were added just below the
surface of the material produced by the extruder.
[0103] The resulting composite material was particularly useful as
synthetic decking material.
Example 2
[0104] In a batch reactor, 16.4 wt % rigid polyol (Bayer 4035) was
combined with 1.9 wt % flexible polyol (Bayer 3900), 0.2 wt %
surfactant (DC-1 97), water, 3.2 wt % pigments, 0.0001 wt % UL-28
organic tin catalyst, and 0.1 wt % 33LV amine catalyst, and
thoroughly mixed for 1 minute. 31.5 wt % Wyoming fly ash was then
added and mixed for an additional 1 minute. Finally, 17.3 wt %
isocyanate (1468A, Hehr), 0.9 wt % chopped brown fiber, 3.5 wt %
chopped glass (0.25 in. diameter), and an additional 25.2 wt %
Wyoming fly ash were added and mixed for 30 seconds. The resulting
material had a resin content of 36%, a ratio of rigid to rubbery
polyol of 90%, a solids content of 64%, a 10% excess isocyanate
content, and a fiber content of 4.4%, all by weight based on the
total composition unless noted otherwise. The resulting material
was suitable for forming synthetic lumber boards.
Example 3
[0105] In a batch reactor, 16.4 wt % rigid polyol (Bayer 4035) was
combined with 1.9 wt % flexible polyol (Bayer 3900), 0.2 wt %
surfactant (DC-197), water, 3.2 wt % pigments, 3.5 wt % chopped
glass (0.25 in. diameter), around 0.4 wt % Mohave bottom ash,
0.0001 wt % UL-28 organic tin catalyst, and 0.1 wt % 33LV amine
catalyst, and thoroughly mixed for 1 minute. 31.5 wt % Wyoming fly
ash was then added and mixed for an additional 1 minute. Finally,
17.3 wt % isocyanate (1468A, Hehr), 0.9 wt % chopped brown fiber,
and an additional 25.2 wt % Wyoming fly ash were added and mixed
for 30 seconds. The resulting material had a resin content of 36%,
a ratio of rigid to rubbery polyol of 90%, a solids content of 64%,
a 10% excess isocyanate content, and a fiber content of 4.4%, all
by weight based on the total composition unless noted otherwise.
The resulting material was suitable for forming synthetic lumber
boards.
[0106] For each of Examples 2 and 3, water was added in amounts
shown below (in percent based on total polyol added); physical
properties of the resulting material were tested, and the results
provided below. The 200 lb impact test was conducted by having a
200 lb man jump on an 18 inch span of synthetic lumber board
2.times.6 inches supported above the ground from a height of about
1 ft in the air, and evaluating whether the board breaks.
TABLE-US-00002 H.sub.2O (% Break 100 psi Hardness Flexural Flexural
200 lb of Density Strength Deflection (Durometer Strength Modulus
impact test Example polyol) (lb/ft.sup.3) (psi) (in) C) (psi) (psi)
(P/f) 2 0.10 63 730 0.15 62 3129 118,331 P 2 0.23 59 650 0.15 57
2786 118,331 P 2 0.40 47 450 0.15 52 1929 118,331 F 3 0.10 63 810
0.15 62 3472 118,331 P
Example 4
[0107] Fiberglass rovings (Ahlstrom, 0.755 g/ft) or brown basalt
rovings (0.193 g/ft) were positioned in a 24 inch mold for
2.times.4 inch synthetic lumber, and stabilized to limit movement
relative to the mold surface (about 0.125 in. in from the mold
surface) and to keep them taut. The rovings were applied dry,
coated and pre-cured with the synthetic lumber composition (minus
ash and chopped glass), and wet with a mixture of 49 wt % rigid
polyol (MULTRANOL 4035), 0.098 wt % surfactant (DC-197), 0.20 wt %
amine catalyst (33LV), and 49.59 wt % isocyanate (Hehr 1468A).
[0108] To the mold was added a synthetic lumber mixture, formed by
combining 16.6 wt % rigid polyol (MULTRANOL 4035), 5.5 wt %
flexible polyol (MULTRANOL 3900), 0.16 wt % surfactant (DC-197),
0.07 wt % water, 3.7 wt % pigments, 0.003 wt % organic tin catalyst
(UL-28, Air Products), and 0.1 wt % amine catalyst (33LV), and
mixing for 1 minute, then adding 26.4 wt % Wyoming fly ash, mixing
for 1 minute, and finally adding 20.4 wt % isocyanate (MRS4,
Bayer), 1.1 wt % chopped brown fiber, 3.4 wt % chopped 0.25 in.
fiberglass, and 22.5 wt % Wyoming fly ash, and mixing for 30
seconds.
[0109] The physical properties of the resulting boards were
assessed, and are indicated below. Control boards were also
prepared to different densities, and their physical properties
evaluated as well. The axially oriented rovings greatly increased
flexural strength, with little added weight. The rovings tend to
have a more pronounced strengthening effect as the load on the
material is increased.
TABLE-US-00003 Flexural Flexural Number of Density Flexural Modulus
@ 100 Modulus @ 200 Roving type rovings Roving coating
(lb/ft.sup.3) strength (psi) psi (Ksi) psi (Ksi)) Basalt 10 Dry 41
1191 73 53 Fiberglass 10 Pre-cured resin 58 4000 188 135 Fiberglass
10 Dry 62 5714 339 169 Basalt 40 Dry 49 2465 96 101 Basalt 40 Dry
31 1650 62 165 Fiberglass 10 Dry 32 2717 37 57 Fiberglass 10 Wet 36
3533 77 93 Fiberglass 5 Wet 36 2410 64 71 Fiberglass 15 Wet 38 4594
171 80 Fiberglass 20 Wet 35 4356 84 80 None 55 1808 147 98 None 66
4724 121 100 None 68 -- 169 135 None 59 2568 70 84 None 45 1319 82
62 None 35 1174 56 63 None 41 746 59 0
[0110] The synthetic lumber produced by the invention was found to
have good fire retardant properties, achieving a flame spread index
of 25, and to produce only small quantities of respirable particles
of size less than 10 .mu.m when sawn. It provides excellent
compressive strength, screw and nail holding properties, and
density. Extruded composite of the invention generally provides
mechanical properties that are even better than those provided by
molded composite.
* * * * *