U.S. patent application number 10/658820 was filed with the patent office on 2007-03-22 for building materials from needle-punched fiber mats with granular heat-activated adhesives.
Invention is credited to Forrest C. Bacon.
Application Number | 20070066174 10/658820 |
Document ID | / |
Family ID | 37884801 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070066174 |
Kind Code |
A1 |
Bacon; Forrest C. |
March 22, 2007 |
Building materials from needle-punched fiber mats with granular
heat-activated adhesives
Abstract
Dry adhesives are embedded within needle-punched fiber mats used
for manufacturing wood-like building materials. During a
cross-lapping operation that lays large ribbons of combed fibers
(such as nylon fibers from shredded carpets) on top of a large
moving conveyor, one or more layers of granular, pellet, fibrous,
film, or other dry adhesive are embedded within the loose mass of
fibers. For example, dimpled rollers, shaker trays, or similar
devices loaded with granular or pelleted adhesives can be
positioned above the conveyor, between cross-lapper machines. The
fiber mass with embedded adhesive is then needle-punched into a
stable, compact, flexible form that can be stored and shipped. When
desired, the mats are run through a heated press that melts the
adhesive, converting it into a binder that turns the mats into
stiff sheets of material comparable to plywood.
Inventors: |
Bacon; Forrest C.; (Conyers,
GA) |
Correspondence
Address: |
PATRICK D. KELLY
11939 MANCHESTER #403
ST. LOUIS
MO
63131
US
|
Family ID: |
37884801 |
Appl. No.: |
10/658820 |
Filed: |
September 8, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60408946 |
Sep 7, 2002 |
|
|
|
Current U.S.
Class: |
442/408 ;
442/402; 442/409; 442/417 |
Current CPC
Class: |
E04C 2/16 20130101; Y10T
442/689 20150401; D04H 1/48 20130101; Y10T 442/682 20150401; D04H
1/488 20130101; D04H 1/60 20130101; Y10T 442/69 20150401; Y10T
442/699 20150401; D04H 1/74 20130101 |
Class at
Publication: |
442/408 ;
442/402; 442/417; 442/409 |
International
Class: |
D04H 3/10 20060101
D04H003/10 |
Claims
1. An article of manufacture, comprising a needle-punched fiber mat
that contains a particulate adhesive embedded within the fiber
mat.
2. An article of manufacture, comprising a building material that
has been manufactured by heated compression of a needle-punched
fiber mat that contained, prior to the heated compression step, a
particulate adhesive embedded within the fiber mat.
3. A method of manufacturing a building material, comprising the
following steps: a. embedding a particulate adhesive within a
fibrous layer that is being created on a conveyor system; b.
compressing the fibrous layer; and, c. subjecting the fibrous layer
to a needle-punching operation.
Description
PRIORITY CLAIM
[0001] This application claims priority under 35 USC 120(e) based
on U.S. provisional application 60/408,946, filed on Sep. 7,
2002.
BACKGROUND OF THE INVENTION
[0002] This invention relates to solid materials handling and to
chemical adhesives, and discloses methods for converting
needle-punched fiber mats (from sources such as shredded recycled
carpets) into waterproof building materials, such as substitutes
for plywood, roofing shingles, etc.
[0003] A method for creating sheets of wood-like materials,
comparable to plywood but essentially waterproof and bug-proof,
using nylon fibers obtained from shredded discarded carpet
segments, is described in published PCT application WO 01/76869
(arising from PCT/US01/11895), by Forrest Bacon et al, the same
Applicants herein. The contents of that published application are
hereby incorporated by reference, as though set forth fully
herein.
[0004] The above-cited PCT application describes a new use for
needle-punched fiber mats. Those types of needle-punched mats,
which have been made for years, are manufactured by a series of
steps that include the following:
[0005] a. segments of discarded carpet are shredded, using a
rotating claw cylinder, to create a mass of rough yarn
material;
[0006] b. the rough yarn material is then combed and pulled apart,
to create a relatively light and fluffy mass of nylon fibers;
[0007] c. the fiber mass is combed into large continuous ribbons
roughly two feet wide and an inch or more thick;
[0008] d. machines called "cross-lappers" are used to deposit these
ribbons transversely, across a slow-moving conveyor system (which
typically is 13 feet wide, in order to make fiber mats that can be
side-trimmed to exactly 12 feet wide); after the ribbons from
several cross-lapper machines (typically, four machines are used in
series) have been deposited onto the conveyor system, the resulting
mass of fibers that rests on top of the travelling conveyor is more
than a foot thick, with low density, and with essentially all
fibers laying in roughly horizontal directions;
[0009] e. the thick mass is compressed to roughly 1/2 inch
thickness, by compression rollers, to form a fibrous mat;
[0010] f. the fibrous mat passes through a needle-punch machine,
which contains a wide steel "platen" with thousands of long needles
having small nicks or barbs on the surfaces of their shafts;
[0011] g. the platen and the barbed needles are hammered against
the mat, about 5 times per second, as the mat passes slowly through
the needle-punching zone;
[0012] h. the barbs on the shafts of the needles grab individual
fibers in the mat, and yank those fibers both upward and
downward.
[0013] When the mat emerges from the needle-punch machine, it is
strong and cohesive, and cannot be pulled apart by hand without
great effort, because of the dense intertwining of the fibers. If
the needle-punching operation is carried out properly, with a
combination of plate width and conveyor speed that establish a
sustained "dwell time" in the needle-punching zone, multiple
thousands of fibers per square yard will be yanked into a
"vertical" (transverse) position. As a result, a needle-punched mat
made from recycled carpets has the general shape, feel, and
flexibility of an extra-thick woolen blanket, and it is held
together entirely by the fibers within the mat, with no need for
expensive chemical adhesives.
[0014] In the past, these types of mats have been used mainly for
two purposes: (i) as underlayments (also called pads, cushions,
etc.) for carpets installed in high-traffic areas, such as in
stores, office buildings, theaters, etc; and, (ii) as padding and
sound insulation in vehicles, such as in automobile trunks.
However, there is a not a high level of demand for these mats,
since those uses are limited, and people generally prefer to have
rubbery foam underlayers, which provide a spring-like bouncy feel,
installed beneath carpets in homes and apartments.
[0015] PCT application WO 01/76869 describes an entirely new and
different use for these types of needle-punched mats. In this new
use, a liquid adhesive is spread between two or more mats, and the
mats are then compressed against each other, using high pressures
to drive the adhesive throughout the entire thickness of both (or
all) mats. This process can be aided by using a two-component
adhesive mixture that undergoes a chemical reaction that releases
millions of tiny gas bubbles, soon after the two components are
mixed together; the formation and release of the gas helps drive
the liquid adhesive throughout the entire thickness of both of the
dense fibrous mats that are being compressed against each other.
One such subclass of adhesives includes specialized types of
poly-alcohol resins that can be mixed with cyanate catalysts, to
form polyurethane adhesives. In one example of a manufacturing
operation, the two liquids can be mixed together, using a mixing
nozzle, immediately before the resulting liquid mixture is spread
across the juncture where two needle-punched mats will be
compressed against each other, by rollers. The mats will then be
held against each other, under pressure until the adhesive sets and
hardens; this can be done by using a "moving belt press", of the
type that is commonly used to manufacture plywood, oriented strand
board, particle board, and similar types of materials, generally
referred to herein as "sheetwood" materials to distinguish them
from planks and other forms of sawed lumber.
[0016] The resulting material, which contains needle-punched mat(s)
that have been thoroughly impregnated with hardened adhesive, has a
stiffness, hardness, and "workability" (i.e., it can be sawed,
drilled, etc.) that are comparable to plywood, oriented-strand
board, etc. However, the stiffened fiber-and-adhesive materials can
be substantially stronger and more resilient than wood, and are
also essentially waterproof and bugproof.
[0017] The main drawback and limitation of this manufacturing
process is that two-component adhesives which will release gas
bubbles, after being mixed together, tend to be expensive, and make
up the large majority of the total cost of manufacturing these
types of boards. Even when the total costs of collecting,
shredding, combing, cross-lapping, and needle-punching discarded
carpet segments are factored in, the purchase price of the adhesive
is likely to be roughly 70 to 80 percent of the total cost of the
final material. However, in the tests that were carried out prior
to this invention, less expensive types of adhesives were not able
to provide the consistency and uniformity that will be required to
achieve widespread acceptance and commercialization of these types
of wood-substitute materials.
[0018] The primary obstacle that prevented the successful use of
inexpensive adhesives, prior to this invention, was the difficulty
that was encountered in getting candidate adhesives to somehow
permeate, diffuse, or otherwise be distributed in an even,
consistent, uniform, and reliable manner, throughout the entire
thickness of a needle-punched fiber mat. As anyone who has
personally inspected a needle-punched mat made from shredded
carpets can attest, the thickness and density of the mat, combined
with the dense and complex intertwining of the fibrous matrix in
the mat, poses a formidable and daunting challenge to any attempt
to successfully drive any form of liquid, granular, or powdered
material through the mat, in an even, consistent, and uniform
manner.
[0019] This poses a major challenge, since evenness, consistency,
and uniformity are essential to sheetwood materials that must
compete against plywood or OSB. If even a single small seam fibrous
mat material, which did not receive enough adhesive to harden
properly, is present in a sheet of a plywood substitute, then that
entire sheet will be unreliable and even dangerous to use in a
building; it will be effectively worthless, since its sale might
subject the seller to large legal liabilities if it is incorporated
into a building and then subsequently fails, due to the one small
seam.
[0020] Nevertheless, the Applicant herein has developed a new
method of creating sheetwood substitutes and other building
materials, from needle-punched fiber mats, using granular
adhesives. The crucial step in this invention centered on creating
and developing a method for distributing a granular adhesive
throughout the thickness of the fiber mat while it is being formed
by the cross-lapper machines and the conveyor system, before the
mat reaches the needle-punch machine.
[0021] Therefore, this new method of manufacture enables the
selection and use of lower-cost granular adhesives, which fall
within a class that is referred to within the industry as "hot
melt" adhesives.
[0022] Accordingly, one object of this invention is to disclose a
method of distributing and embedding heat-activated adhesives, in
granular, powdered, or similar form, throughout the thickness of a
needle-punched fiber mat, to render the mat useful for
manufacturing a plywood substitute or other building material.
[0023] Another object of this invention is to disclose a method of
using low-cost "hot melt" adhesives, during the manufacture of
plywood substitutes and other building materials from
needle-punched fiber mats.
[0024] Another object of this invention is to disclose plywood
substitutes and other building materials, which contain
needle-punched fiber mats that are held together and stiffened by
means of granular or other low-cost "hot melt" adhesives.
[0025] Another object of this invention is to disclose the use of
spun fiberglass, virgin nylon fibers, or other fibrous materials,
to manufacture exceptionally strong, hard, waterproof, durable, and
otherwise highly useful building materials.
[0026] These and other objects of the invention will become more
apparent through the following summary, drawings, and detailed
description.
SUMMARY OF THE INVENTION
[0027] This invention discloses methods and machines for
manufacturing building materials (including sheets of wood-like
material comparable to plywood), using particulate adhesives that
are embedded and distributed within needle-punched fiber mats. This
manufacturing process uses the same types of cross-lapping and
conveyor machines that are used to manufacture conventional
needle-punched fiber mats, of the type that are widely used as
carpet underlayers in commercial sites such as stores and
restaurants. However, during the cross-lapping operation, and
before a needle-punch operation is carried out on the mass of
fibers that has been laid on top of the conveyor, one or more
layers of particulate adhesives (which normally will be granular,
in small pellets, etc.) are deposited and embedded into the large
combed-fiber ribbons that are being laid across the conveyor. This
can be done in any of several ways, such as: (i) by using one or
more additional cross-lapping machines (which can be positioned on
the opposite side of the conveyor system from the fiber-handling
cross-lapping machines) to deposit one or more layers of granular
adhesive onto or into the growing mass of fibers that is being
deposited onto the conveyor; (ii) by sprinkling a granular adhesive
across the upper surface of each large fiber ribbon as it leaves a
combing machine and travels toward the cross-lapper head that is
travelling back and forth over the conveyor; (iii) using one or
more granular conveyors (such as moving belts, etc.) to
continuously deliver granular adhesives to distributing devices,
such as shaker trays or dimpled rollers that are mounted over the
conveyor (presumably positioned between cross-lapper heads) to
sprinkle a steady supply of the granular adhesive on top of the
fiber mass that is being formed on the conveyor. Alternately or
additionally, an inexpensive "hot melt" adhesive in a fibrous,
stranded, or other form can be treated like shredded nylon fibers,
incorporated directly into (or laid across the top surface of) the
large combed-fiber ribbons that are being handled by the
cross-lapper machines.
[0028] In addition, if desired, layers of adhesive material (in
powdered, fibrous, or stranded form, continuous thin sheets, etc.)
and/or polymers with low melting temperatures (such as
polypropylene or other polyolefins) also can be laid on either side
(top and/or bottom) of the mass of fibers that is being formed into
a mat that will be needle-punched.
[0029] This type of adhesive deposition, carried out on the same
conveyor system that is being used to create the thick mass of
nylon fibers that will be compressed and then needle-punched, can
distribute and embed a "hot melt" adhesive throughout essentially
the entire thickness (or any targeted portion thereof) of a
needle-punched fiber mat, regardless of how thick or heavy the
needle-punched mat will be. The resulting mats are highly stable,
and can be stored for months before the heated compression
step.
[0030] When the needle-punched mat containing the hot-melt adhesive
is passed through a heated press, the adhesive will melt into a
highly sticky liquid that will be distributed throughout the entire
thickness of the mat. This can generate a hardened wood-like
material with a high level of consistency, uniformity, and
strength. Accordingly, by allowing a manufacturer to eliminate the
need for expensive two-component liquid adhesives that will release
gas bubbles shortly after the two components are mixed, this method
can reduce the total costs of the building materials that are being
manufactured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIGS. 1 and 2, which are prior art, depict the top and side
views of a conveyor system that has four cross-lapper machines.
Each cross-lapper deposits a continuous ribbon, made of combed
nylon fibers, across the conveyor, which is moving from right to
left in the drawings. These ribbons create a large and thick mass
of fluffy material, which is then compressed by rollers and passed
through a needle-punch machine. These systems have been used for
years to manufacture needle-punched fiber mats, for use as carpet
underlayers and as insulation in automobile trunks.
[0032] FIG. 3 depicts a shaker tray for dispersing particulate
adhesives, positioned adjacent to the rails that support a
cross-lapper head that travels above a conveyor system as shown in
FIGS. 1 and 2.
[0033] FIG. 4 is a perspective cutaway view depicting a dimpled
roller device for dispersing particulate adhesives.
DETAILED DESCRIPTION
[0034] As summarized above, this invention discloses methods and
devices for embedding and distributing particulate adhesives within
needle-punched fiber mats. This can allow the use of relatively
inexpensive adhesives in the manufacture of various types of
building materials (including sheets of wood-like material,
comparable to plywood, as disclosed in published PCT application WO
01/76869, as well as various other types of building material (such
as roofing shingles, embossed layers, laminated beams, etc.) that
can be made from recycled carpets or other synthetic fibers.
[0035] This manufacturing process uses the same types of
cross-lapping and conveyor machines that are used to manufacture
conventional needle-punched fiber mats, of the type that are widely
used as carpet underlayers in commercial sites such as stores and
restaurants. A conventional system of this type, which is prior
art, is shown as system 200 in FIG. 1 (a top or plan view) and FIG.
2 (a side or elevation view). These two figures are formal version
of the informal drawings that were filed as FIGS. 4 and 5 in PCT
application WO 01/76869, and the callout numbers have not been
changed. Additional information on those types of conveyor and
cross-lapper machines is provided in PCT application WO 01/76869,
the contents of which are incorporated herein by reference, as
though fully set forth herein.
[0036] In system 200, a set of four garnett machines 240 (also
referred to as machines 242 through 248) is shown next to a
conveyor belt 230. As conveyor belt 230 moves forward, each garnett
machine continuously receives a load of fiber through an inlet
(represented by inlet 243, on top of garnett machine 242). Inside
each garnett machine, the fiber is combed and pulled, in a manner
that opens the fiber into a wide, flat ribbon that emerges from the
garnett machine. Each ribbon enters a cross-lapping device;
cross-lapper 250 (described in more detail below) distributes the
output from garnett machine 242, while cross-lappers 262, 264, and
266 distribute the outputs from garnett machines 244, 246, and 248,
respectively.
[0037] One component of each cross-lapping device travels back and
forth across the main axis of the conveyor belt 230. This
component, indicated by callout arrow 250, can be referred to by
terms such as the operating head, the travelling head, the output
unit, etc.; alternately, that travelling component can be referred
to as the cross-lapping device, and the supporting rails and
driving system can be regarded as just supporting devices.
[0038] An exemplary cross-lapper head 250 is illustrated in more
detail in FIG. 3. It typically comprises a rectangular device that
rides on four wheels 251. Wheels 251 typically have concave rounded
pulley shapes, so that they will travel securely on parallel
tubular rails 253, which usually are made of stainless steel or a
similar smooth material. Cross-lapper heads are typically powered
by chain drives, to ensure exact travel speed and placement with no
risk of slippage as would occur with belts. A ribbon of combed
fiber 255 is also shown in FIG. 3, being carried by the
cross-lapper head 250 until it is deposited onto the conveyor
230.
[0039] The recipricating and cyclical motion of cross-lapper 250,
back and forth across the conveyor 230, is referred to herein as
"transverse" motion, and is shown by the directional arrows
superimposed on each travelling head in FIG. 1.
[0040] As shown by the directional arrows, conveyor 230 is
travelling toward the left, in FIGS. 1 and 2. As depicted in the
side view shown in FIG. 2, conveyor 230 is empty as it begins to
pass in front of garnett machine 242. Each garnett and cross-lapper
combination deposits a thick ribbon of low-density fiber on top of
the conveyor 230, thereby forming an uncompressed mat 210, which
continues to grow thicker as it moves closer to the compression
rollers 270 and the needle-punch machine 300. As the uncompressed
mat 210 reaches end roller 231, the mat 210 is lifted off of
conveyor belt 230 by the compression rollers 270. The belt 232
travels downward around end roller 231, and returns to garnett
machine 242, empty and ready to start another cycle.
[0041] The first garnett machine 242 and the first cross-lapper
250, working together, lay down a first ribbon of low-density
fiber, shown by dashed lines in FIG. 1, which (for the first
ribbon) are identified by callout arrow 259, which points to its
"leading" edge, and callout arrow 260, which points to its
"trailing" edge. Because the conveyor belt 230 moves steadily
forward while the cross-lappers each move back and forth across
belt 230, each ribbon being laid down by each cross-lapper will be
deposited in an angled manner. As shown by the first ribbon, a
first angle (shown by leading edge 259) is created while
cross-lapper 250 moves away from garnett machine 242 and travels
toward far (distal) position 256, and a second angle (shown by
trailing edge 260) is created while the cross-lapper 250 returns to
its near (proximal) position 258.
[0042] As indicated by the increasing density of the dashed lines
in FIG. 1, and by the increasing thickness of uncompressed mat 210
shown from the side in FIG. 2, fibrous mat 210 grows substantially
thicker as it passes in front of each garnett machine. In testing
operations that created high-quality wood substitute materials, an
uncompressed fibrous mat created by four garnett machines in series
averaged about 12 inches (about 30 cm) or slightly higher, in
thickness, before it entered the compression rollers.
[0043] As it reaches the end of the conveyor belt 230, the
uncompressed mat 210 enters one or more compression rollers 270.
These rollers flatten the uncompressed mat 210 into a relatively
uniform desired thickness, such as about 1/2 to 1 inch thick. This
material is shown as compressed sheet 275. To minimize shear forces
and other potential tearing stresses on the mat, which does not yet
have any form of reinforcement, it is generally preferable to use
two or more sets of paired compression rollers, mounted above and
below the mat.
[0044] The compressed mat 275 enters needle-punch machine 300. This
machine comprises a reciprocating drive mechanism, such as an arm
302 with one end mounted on a rotating wheel 304, driven by
electric motor 306. Arm 302 is coupled to needle platen 310, which
has thousands of needles 312 exposed on its bottom surface, in a
regular gemoetric array. As mentioned in the Background section,
each needle has a number of barbs or nicks, on the portion of the
needle shaft that will pass back and forth through the compressed
mat 275. Accordingly, as wheel 304 rotates, typically at a rate of
about 5 cycles per second, the entire set of barbed needles 312 is
repeatedly forced down through the compressed mat 275, and then
lifted up again. To facilitate the needle-punching operation, the
mat 275 passes across a supporting anvil 320 which is provided with
a relatively narrow trough, directly beneath the needle zone, to
accommodate the needle tips that emerge through the bottom of the
mat.
[0045] As the needle-punching process is carried out, the barbs on
the needle shafts will pull thousands of fibers both upward and
downward, in each square yard of the mat. This substantially
increases the cohesive strength of the fiber mat, and creates a
needle-punched mat 350. This mat 350 can also be regarded as having
an "interwoven" or "interlaced" matrix or lattice. The combination
of (i) fibers oriented in different directions, and (ii) open pore
spaces that were created or enlarged by the needles and barbs
during the punching process, help create what is believed to be an
ideal porous structural matrix for subsequent processing as
disclosed herein.
Devices for Dispersing Particulate Adhesives
[0046] During the cross-lapping operation, and before a
needle-punch operation is carried out on the mass of fibers that
has been laid on top of the conveyor, a substantial quantity of
particulate adhesives (which will be in a form such as granules,
flakes, small pellets, etc.) are deposited, embedded, or otherwise
distributed into and through the uncompressed mat 210 that is being
formed on top of the conveyor 230.
[0047] This can be done in any of several ways, depending on the
type of particulates that are being dispersed. For example, if
small and relatively hard pellets, or large irregular-shaped
granules, are being dispersed, a shaker tray can be used, as shown
schematically in FIG. 3. This system uses a relatively wide tray
510, having a flat bottom 512 with multiple outlet holes 514 (also
called orifices, apertures, etc.) passing through it. If desired, a
coarse screen 516 can be fitted into the bottom of the tray 510,
and additional devices (such as a slidable sheet that can be used
to close the outlet holes 514) can also be provided. Alternately,
instead of providing outlet holes in the bottom of a tray, a shaker
tray can be tilted in a controlled manner that will cause
particulates to spill out over one side of the tray at a suitable
rate, in a manner comparable to using a weir-type skimmer to
control the amount of liquid that passes over a barrier.
[0048] Tray 510 is mounted in a non-rigid manner (depicted by
springs 520 and 522) to a supporting member 524, which can be a
beam, shaft, etc. A powered device is used to impart a vibrating,
shaking, oscillating, orbital, or comparable motion to the tray
510, so that pellets, granules, or other particulates that have
been loaded into the tray (this can be done by any suitable type of
delivery system) will fall out of the tray in a more even, uniform,
and distributed manner. The device shown in FIG. 3 comprises an
electric motor 530 having an eccentric weight 532 mounted to a
rotating shaft.
[0049] Shaker trays and pelleted adhesives are not ideal, from the
viewpoint of either material handling, or consistent and uniform
distribution of melted adhesive throughout the final hardened
product. However, pelleted materials can be made inexpensively, and
in very large quantities, by extrusion machinery, and they may be
less expensive than adhesives made in powdered or small granular
form, or in thin flakes. Accordingly, shaker trays should be
recognized as one option, and can be evaluated for use with any
particular type of adhesive.
[0050] If the particulate adhesive is in the form of a powder,
small grains, or thin flakes, it likely will be preferable to use a
dimpled roller system, rather than a shaker tray. This type of
system is depicted, in a perspective cutaway view, in FIG. 4, as
roller system 600. This system comprises a trough or tray 602, made
of sheet metal or similar material, and preferably having a wide
top, for easier loading, and to provide greater capacity and reduce
the risk of inadvertently running out of adhesive. A cylindrical
roller 610 with a large number of relatively small and shallow
depressions 612 (generally called dimples) that have been molded or
machined into its surface is positioned at the bottom of the tray,
and it rotates when te device is in use. Two flexible flaps 614 and
616 (made of a rubberized or other elastomeric material) press
against the sides of the roller 610, and prevent spillage of excess
adhesive out of the tray.
[0051] The rubber flap 614 prevents adhesive granules from leaving
tray 602, unless they have settled into one of the dimples 612 on
roller 610 (this settling process occurs due to gravity, as the
upper surface of the roller passes beneath the pile of adhesive
granules 630, which is stacked up on top of the roller 610, in tray
602.
[0052] This type of mechanism is commonly used for dispersing
particulates across a linear distance, because it provides a simple
yet effective method for controlling the rate of output of the
particulates. If a greater dispersion rate is desired, the speed of
rotation of the roller 610 is increased; conversely, if lower
dispersion rates are desired, the speed of rotation of the roller
610 is decreased.
[0053] Shaker trays and dimpled rollers are merely examples of
devices that can be used to disperse particulate adhesives across
the entire width of a conveyor system. Other useful devices and
systems are known, and can be evaluated for use as described
herein, with any particular type of particulate adhesive.
[0054] These types of particulate dispersion devices can be placed
at any of numerous locations, in a conveyor system such as
illustrated in FIGS. 1 and 2. As examples, three dispersion units,
each of which can span the entire width of the conveyor 230, can be
placed between each of the four cross-lapper machines 242-248.
[0055] In addition, if desired, layers of adhesive material (in
powdered, fibrous, or stranded form, continuous thin sheets, etc.)
and/or polymers with low melting temperatures (such as
polypropylene or other polyolefins) also can be laid on either side
(top and/or bottom) of the mass of fibers that is being formed into
a mat that will be needle-punched.
[0056] Alternately or additionally, an inexpensive "hot melt"
adhesive in a fibrous, stranded, or comparable form, can be treated
like shredded nylon fibers, allowing it to be incorporated directly
into (or laid across the top surface of) the large combed-fiber
ribbons that are being deposited on the conveyor by the
cross-lapper machines.
[0057] It also should be noted that, by using embedded and
distributed adhesives, new materials and devices that have modified
surface (or "skin") layers, and discrete embedded layers made with
heterogenous materials, can be manufactured.
"Hot Melt" Particulate Adhesives
[0058] A broad variety of particulate adhesives are known, and any
of them can be evaluated for use as disclosed herein. In general,
the three factors that will require initial consideration, before
proceeding further in any such evaluation, include:
[0059] (i) the cost of a candidate adhesive, which usually is
expressed on a per-weight basis;
[0060] (ii) its melting temperature, which must be lower than the
melting temperature of the nylon strands in the needle-punched
fiber mats (if recycled carpet material is being used to create the
fiber mats), and which generally will require lower heating costs
if a lower melting temperature can be used;
[0061] (iii) its ability to adhere tightly to the type of fibers in
the needle-punched mats (which generally will include nylon, with
lesser quantities of polypropylene, if recycled carpet material is
used to create the fiber mats).
[0062] Those items of information are well-known to any company
that actively sells granular adhesives in large quantities, and
various such companies can be located easily. Such companies
include several large manufacturers, such as BASF, Georgia-Pacific,
and the 3M Company, as well as numerous distributors.
[0063] Most types of particulate adhesives that are likely to be of
interest and usually referred to within the industry as "hot melt"
adhesives; this category distinguishes them from liquid adhesives
that use solvents which will evaporate during curing. A number of
major advances in hot-melt adhesives were created during the 1980's
and 1990's, driven partly by concerns over the release of organic
solvents into the atmosphere. As a result, an excellent overview of
hot-melt adhesives is available from the Pacific Northwest
Pollution Prevention Resource Center (PPRC), which has posted an
outstanding compilation and review in its website, at
http://www.pprc.org/pprc/p2tech/hotmelt/hmintro.html.
[0064] Very briefly, some of the more widely used subcategories of
hot-melt adhesives include the following:
[0065] a. EVA, which refers to ethylene-vinyl-acetate
adhesives;
[0066] b. SIS, which refers to styrene-isoprene-styrene
adhesives;
[0067] c. SBS, which refers to styrene-butadiene-styrene
adhesives;
[0068] d. APAO, which refers to amorphous poly-alpha-olefin
adhesives;
[0069] e. polyethylenes;
[0070] f. polyamides (however, it should be noted that nylon is
itself a polyamide, and the melting points of polyamide adhesives
generally will render them either unusable for use with nylon fiber
mats, or unnecessarily expensive, from the viewpoint of heating
requirements);
[0071] g. phenolics, including phenolic-formaldehyde compounds.
[0072] These is just a brief listing, and extensive additional
information is available from sources such as the PPRC website
(which provides a good introduction), and from vendor companies,
who have technical specialists who are closely familiar with the
details and the performance traits of the adhesives they sell.
[0073] Accordingly, any such particulate adhesive can be evaluated
for use as disclosed herein.
[0074] It must also be clearly and explicitly recognized that in
any such evaluation, the details of the intended final product
(including the exact type or mixture of fibers that will used to
make the needle-punched fiber mat that will be impregnated by the
particulate adhesive) must be taken carefully into account. A wide
variety of such building materials can be made by using adhesives
to stiffen needle-punched mats, including (1) sheetwood
substitutes, which can be used instead of materials such as
plywood, OSB, particle board, paneling, siding, etc; (2) embossed
materials with non-planar surfaces, such as shingle substitutes,
adhesive backer boards, sheets with grooves that can be laid on top
of freshly-laid concrete to allow moisture to escape from the
concrete, etc; (3) laminated beams, which can be made with any
desired thickness, width, and length, by gluing together layers
that have been sawed into planks or comparable shapes; and, (4)
other items (such as door thresholds, flooring transition strips,
etc.) that would be more useful if from exceptionally strong,
durable, and waterproof materials.
[0075] Any of these building materials can be made from nylon
fibers obtained from recycled carpet segments (which can be either
post-consumer waste, or never-waled-on "post-industrial" waste).
Alternately, because the building materials that can be made from
needle-punched fiber mats and adhesives have extraordinary
performance traits, they can also be made from virgin nylon fibers,
if desired, or from mixtures of virgin and recycled fibers.
[0076] In addition, still other types of fibers can be used, if
desired. As just one example, the Applicant herein recently tested
spun fiberglass strands, that were formed into a needle-punched mat
and then impregnated with an adhesive that binds tightly to
fiberglass. The resulting material was extraordinarily hard and
strong, and was closer, in its physical and performance traits, to
stainless steel, than to wood.
[0077] It should also be noted that needle-punched fiber mats that
contain embedded particulate adhesives are highly stable, and can
be stored for months or possibly even years, before a heated
compression treatment is used to manufacture them into final
hardened products. Accordingly, adhesive-containing fiber mats can
become a valuable item of commerce in their own right, as an
article of manufacture, and are regarded as one embodiment of this
invention.
[0078] In at least some situations, when fiber mats are being used
that have high polypropylene contents, from shredded discarded
carpet segments, it may be preferable to use an adhesive that has a
lower melting or activation point that the melting point of
polypropylene. This can provide at least one clear advantage, in
terms of reduced energy requirements for both (i) heating any
presses up to high temperatures, and (ii) adequately ventilating
and cooling the building where the press is operating. It may also
be able to provide one or more other advantages as well, in
avoiding and eliminating the tendency of polypropylene to shrink
and distort somewhat when it melts, which otherwise can require
additional steps to ensure that shrinkage or distortion of the
polypropylene will not cause warping or other distortion of a sheet
of fibrous wood substitute.
[0079] It also should be noted that similar treatments, using
adhesives, can be used to convert various other types of fibrous
mats into substitutes for plywood, particle board, oriented-strand
board (OSB) and other building materials. Examples of fibrous mats
that can be evaluated for such use using no more than routine
experimentation include fibrous mats that are often called
"air-laid" or "bat-formed" by those familiar with this field of
art.
[0080] It should also be recognized that, if adhesives are used
which are embedded or otherwise distributed throughout the entire
thickness of the fibrous mat before it is heat-treated or otherwise
treated to activate the adhesive, then it can become practical and
feasible to compress essentially any (reasonable) number of layers,
each layer having essentially any thickness that is of genuine
interest, into a final building material such as a plywood
substitute. The final material will have a thickness that will
depend on the number and the thickness of the fibrous layers that
were incorporated into the final material (this type of total fiber
weight usually can be expressed in terms such as weight per square
foot, square yard, or square meter, or in terms such as weight per
sheet of material).
[0081] Thus, there has been described a new and improved approach
to manufacturing building materials from needle-punched fiber mats,
using particulate adhesives. Although this invention has been
exemplified for purposes of description by reference to certain
specific embodiments, it will be apparent to those skilled in the
art that various modifications, alterations, and equivalents of the
illustrated examples are possible.
* * * * *
References