U.S. patent application number 12/843265 was filed with the patent office on 2010-11-18 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 | 20100292397 12/843265 |
Document ID | / |
Family ID | 34795182 |
Filed Date | 2010-11-18 |
United States Patent
Application |
20100292397 |
Kind Code |
A1 |
Brown; Wade |
November 18, 2010 |
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 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.
Inventors: |
Brown; Wade; (Mooresville,
NC) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
CENTURY-BOARD USA, LLC
Mooresville
NC
|
Family ID: |
34795182 |
Appl. No.: |
12/843265 |
Filed: |
July 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10764012 |
Jan 23, 2004 |
7763341 |
|
|
12843265 |
|
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Current U.S.
Class: |
524/590 |
Current CPC
Class: |
C08G 18/0895 20130101;
C08G 18/4816 20130101; B29C 39/16 20130101; Y10T 428/24438
20150115; C08K 3/22 20130101; C08L 2203/14 20130101; Y02W 30/91
20150501; C08J 2375/08 20130101; C08G 2110/0083 20210101; C08J
5/043 20130101; Y10T 428/24479 20150115; C08G 2110/0066 20210101;
C04B 26/16 20130101; C08J 5/04 20130101; 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: |
524/590 |
International
Class: |
C08L 75/04 20060101
C08L075/04 |
Claims
1. A polymer composite material comprising: a polyurethane formed
by reaction of a mixture comprising: a poly- or di-isocyanate; a
first polyol comprising a polyether polyol, the first polyol having
a first molecular weight in the range of 400 to 481, the first
polyol being more rigid relative to the second polyol; and a second
polyol comprising a polyether polyol or a polyester polyol, the
second polyol having a second molecular weight which is greater
than the first molecular weight and falling in the range of 500 to
3000 and being more flexible relative to the first polyol, wherein
the second polyol is about 5 wt % to about 20 wt % of the total
weight of the first and second polyols; and wherein the
polyurethane is less rigid than a second polyurethane that would be
formed by the reaction of the first polyol and the poly- or
di-isocyanate in the absence of the second polyol; and an inorganic
particulate material comprising one or more of fly ash, bottom ash,
particulate glass and granite tailings dispersed in the polymer
matrix, the inorganic particulate material being about 60 wt % to
about 72 wt % of the total weight of the composite material.
2. The polymer composite material of claim 1, wherein the material
is foamed.
3. The polymer composite material of claim 1, further comprising
one or more inorganic fibers.
4. The polymer composite material of claim 1, further comprising
axially oriented fiber rovings disposed on, in, or beneath a
surface of the composite.
5. The polymer composite material of claim 1, wherein the inorganic
particulate material is one or more of a fly ash, bottom ash, or
particulate glass.
6. The polymer composite material of claim 1, wherein the inorganic
particulate material has a particle size distribution ranging from
about 0.0625 in. to below about 325 mesh.
7. The polymer composite material of claim 1, wherein the inorganic
particulate material contains less than about 0.5 wt % water.
8. The polymer composite material of claim 1, wherein the composite
material is self-skinning.
9. The polymer composite material of claim 1, having a density
ranging from about 20 lb/ft.sup.3 to about 60 lb/ft.sup.3.
10. The polymer composite material of claim 1, wherein the polymer
matrix composite material additionally comprises a polyisocyanurate
formed by reaction of the monomeric or oligomeric poly- or
di-isocyanate with water.
11. The polymer composite material of claim 1, wherein the poly- or
di-isocyanates comprises a methylene diphenyl diisocyanate
(MDI).
12. The polymer composite material of claim 11, wherein the MDI
provides about 5% to about 10% excess NCO groups.
13. The polymer composite material of claim 1, wherein the ratio of
isocyanates to polyols, based on equivalent weights, is from about
0.5:1 to about 1.5:1.
14. The polymer composite material of claim 1, wherein the second
polyol is about 15 wt % of the total weight of the first and second
polyols.
15. The polymer composite material of claim 1, wherein the first
polyol is present in an amount of about 6 to about 18 wt % and the
second polyol is present in an amount of about 10 wt % or less,
based on the total weight of the composite material.
16. The polymer composite material of claim 1, wherein the
inorganic particulate material is one or more of a fly ash and
bottom ash.
17. The polymer composite material of claim 1, having a flexural
strength of at least 1319 psi.
18. The polymer composite material of claim 1, wherein the
composite material comprises extruded composite material.
19. The polymer composite material of claim 1, wherein the
composite material comprises extruded polyurethane and inorganic
particulate material.
20. A polymer composite material, comprising: a polyurethane formed
by reaction of a mixture comprising: a poly- or di-isocyanate; a
first polyol comprising a polyether polyol, the first polyol having
a first molecular weight; a second polyol comprising a polyether
polyol or a polyester polyol, the second polyol having a second
molecular weight greater than the first molecular weight, wherein
the second molecular weigh is in the range of 500 to 3000, wherein
the second polyol is about 5 wt % to about 20 wt % of the total
weight of the first and second polyols; and wherein the
polyurethane is less rigid than a second polyurethane that would be
formed by the reaction of the first polyol and the one or more
monomeric or oligomeric poly- or di-isocyanates in the absence of
the second polyol; and an inorganic particulate material, the
inorganic particulate material being about 60 to about 74 wt % of
the total weight of the composite material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of Ser. No. 10/764,012,
filed Jan. 23, 2004, which is incorporated by reference in its
entirety herein.
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.
[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.
SUMMARY OF THE INVENTION
[0010] 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.
[0011] 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.
[0012] 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.
[0013] In a more specific embodiment, the invention relates to a
polymer matrix composite material, comprising:
[0014] (1) a polyurethane formed by reaction of [0015] (a) one or
more monomeric or oligomeric poly- or di-isocyanates; [0016] (b) a
first polyether polyol having a first molecular weight; and [0017]
(c) an optional second polyether polyol having a second molecular
weight lower than the first molecular weight; and
[0018] (2) optionally, a polyisocyanurate formed by reaction of a
monomeric or oligomeric poly- or di-isocyanate with water or other
blowing agents;
[0019] (3) a particulate inorganic filler.
[0020] 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 an synthetic lumber. Accordingly, another specific embodiment of
the invention relates to an 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.
[0021] 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:
[0022] (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;
[0023] (2) optionally introducing reinforcing fibrous materials
into the mixture;
[0024] (3) introducing inorganic filler into the mixture;
[0025] (4) introducing poly- or di-isocyanate into the mixture;
and
[0026] (5) allowing the exothermic reaction to proceed without
forced cooling except to control runaway exotherm.
[0027] 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.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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."
[0034] 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, rigid
(relative to the second) polyol and the other a higher molecular
weight, more flexible (relative to the first) polyol. The amount of
rigid polyol is carefully controlled in order to avoid making the
composite too brittle. An amount of flexible 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.
[0035] In general, desirable polyols include polyether polyols,
such as MULTRANOL (Bayer), including MULTRANOL 3400, which has a
molecular weight of about 3,000, or MULTRANOL 4035, which has a
molecular weight of about 438; ethylene glycol, which has a
molecular weight of about 62; diethylene glycol, which has a
molecular weight of about 106; triethylene glycol, which has a
molecular weight of about 150; dipropylene glycol, which has a
molecular weight of about 134; glycerol, which has a molecular
weight of about 92; 2-butyn-1,4-diol, which has a molecular weight
of about 86; neopentyl glycol, which has a molecular weight of
about 104; 1,2-propanediol, which has a molecular weight of about
76; pentaerythritol, which has a molecular weight of about 136;
mannitol, which has a molecular weight of about 182;
1,6-hexanediol, which has a molecular weight of about 118;
1,3-buytylene glycol, which has a molecular weight of about 90;
hydrogenated bisphenol A, which has a molecular weight of about
240; 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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 polyol-isocyanate
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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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).
[0045] 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.
[0046] 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.
[0047] 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 to below 325 mesh have
been found to be particularly suitable
[0048] 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.
[0049] The process for producing the composite material may be
operated in a batch, semibatch, 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.
[0050] 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.
[0051] 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.
[0052] 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 U.S.
Pat. No. 7,211,206, 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.
[0053] 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 %.
[0054] The invention can be further understood by reference to the
following non-limiting examples.
Example 1
[0055] A polymer composite composition was prepared by introducing
9.5 wt % rigid polyol (MULTRANOL 4035, Bayer, molecular weight of
about 438), 0.3 wt % rubber polyol (ARCOL LG-56, Bayer, molecular
weight of about 3,000), 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 1/4 to 1/2 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.
[0056] The resulting composite material was particularly useful as
synthetic decking material.
Example 2
[0057] In a batch reactor, 16.4 wt % rigid polyol (Bayer 4035) was
combined with 1.9 wt % flexible polyol (Bayer 3900, molecular
weight of about 4,800), 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
[0058] 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.
[0059] 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 200 lb H.sub.2O Break 100 psi Hardness Flexural
Flexural impact (% of Density Strength Deflection (Durometer
Strength Modulus 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
[0060] 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).
[0061] 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.
[0062] 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 Flexural Roving Number of Roving
Density strength Modulus @ 100 Modulus @ 200 type rovings coating
(lb/ft.sup.3) (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
[0063] 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.
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