Note: Descriptions are shown in the official language in which they were submitted.
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Title: "FIBROUS MAT AND PRODUC~ AND
M:ETHOD OF MAKING THE SAME"
~ his invention relates generally to fiber
technology. The fibers may, for example, be of tubular
S solid or cellular form and are of natural or synthetic
material. More particularly, the invention refers to
fibrous mat which may be in a continuous length or in
individual sections, product made from the mat, and a
method of making the same.
10 BACKGROUND AND SUMMARY OF THE INVENTION
While a variety of dif~erent fibers may b~
used in carrying out this invention, fibers of cellu~
losic material are stressed throughout this specifica-
tion not only because of their suitability DUt also
because many are readily available from virgin or re-
claimable sources and are relatively inexpensive. Wood
fibers constitute an example of such a cellulosi~
material.
Fibe~board, particle board and hardboard are
terms applied to a variety of products made primarily
from wood fibers, wood chips or shavings. It is known
to form these products by a so-called wet slurry process
in which wood fibers are mix~ with water and other
chemicals and formed into a slurry which is applie~
over a pattern having the desired form~ While satis-
factory products can be formed by the wet slurry
process, it is a relatively expensive process not
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only in terms of the amount of energy re~uired but also
because of its long manufacturing cycle time and the
cost of cleaning the effluent resulting from the process
prior to dumping.
It has also been known to form wood component
based products by dry processing, but these previously
known dry processes are capable of producing products
having only relatively flat simple shapes.
It is a primary object of this invention to
provide a unique dry process of forming products con-
sisting essentially of two types of fibers, one of which
is a natural or synthetic fiber, sometimes referred to
as a base fiber, and the other of which is a linking or
carrier fiber adapted to intertwine or interlock with
the base fibers. The base and carrier fibers may be
either virgin or reclaimed. Suitable ~ase fibers are
made of materials such, for example, as wood, jute,
sisal, cotton, coconut, kapok, rayon,acetate, triacetate,
paper, graphite, glass, mineral wool, and other
synthetic fibers. Product~ having far more difficult
and complex shapes can be made by this new dry
process than could possibly be made by previously
known dry processes. Products made by the method of
t~is invention can be formed relatively fast and
~5 inexpensively into a variety of items sucll, for
example, as decorative trim panels, automotive head-
liners, door panels, instrument panels, center trim
pillars, package trays, consoles, furniture, luggage,
building materials, packaging, automotive components,
and the like. Such a product may have areas of
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differing density to provide portions that are soft to
the touch or to provide visual embossing, and provide
both thermal and accoustical insulation.
A further object is to provide relatively
S flat, flexible, formable ~iber mat in continuous form
or in sections from which products can be made; also
to provide a method of making the mat and the product.
In accordance with a specific embodiment of
the invention, the mat may comprise a mixture of wood
fibers and thermoplastic carrier fibers that mechani-
cally intertwine or interlink with the wood fibers andare bonded or adhered to them to form interlocking
connections which resist separation. The mat fibers
are adhered together by heating the mat to a tem-
perature and for a period of time such that the thermo-
plastic carrier fibers soften and become sufficientlytacXy to heat-seal to the wood fihers and to each
other, but still substantially retain their essentially
fibrous form. The carrier fibers add substantial
flexural strength to the mat so that even when products
molded therefrom have co~plicated or difficult shapes
and include sharp bends and cut-outs, the body of the
mat will nevertheless hold together without ripping
or tearing when thè mold parts close. Other materials
may be added to the formulation of the mat depending
upon the characteristics desired in the finished
product. As an example, a suitable thermosetting
resin may be employed which will cure and set during
~olding to add structural stiffness and heat distor-
tion resistance to the product.
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BRIEF DESCRIPTION OF' THE l:)RAWINGS
These and other objects and features of the
invention will become more apparent as the following
description proceeds, especially when considered with
accompanying drawings wherein:
~ ig. 1 is a perspective view of a section of
fibrous mat made according to the present invention.
Fig. 2 is a perspective view of a typical
product that can be made from the section of mat shown
in Fig. 1.
Fig. 3 is a flow diagram of the method by
which the mat is made.
Fig. 4 is an enlarged fragmentary diagrammatic
view showing the relationship between fibers in the mat.
15 DETAILED DESCRIPTION
- Referring now more particularly to the
drawings, the numeral 10 generally designates a pro-
duct which is relatively stiff or self-supporting, and
12 generally designates a section of fibrous mat from
which the product is made.
The mat section 12 is formed of a multi-
plicity of fibers, virgin or reclaimed, including a
mixture of base fibers 14 and carri~r fibers 16. In
Fig. 4, the base fibers 14 are shown in solid lines
and the carrier fibers in dotted lines as a simple
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means of distinguishing between the two. The base fibers 14
may be of natural or synthetic materials. Suitable natural
materials may be cellulosic such as wood, paper, coconut, cotton,
jute, sisal, or kapok Suitable synthetics might be fibers of
glass, rayon, acetate or triacetate. Other suitable materials
would be mineral wool and graphite. Preferably the base fibers
areof wood,virgin, or reclaimed, and are obtained from any suit-
able tree, such for example, as-~e aspen. The carrier fibers may
be made of material selected from the vinyl family, the poly-
ester family, the polyolefin family, the polyamide family, andany physical or chemical combination of those families. Examples
of polyolefins are polyethylene and polypropylene. An example
of a polyamide is nylon. Examples of vinyls are Saran , Vinyon
and polyvinyl chloride (PVC). Saran is a polymer composed of
at least 80% by weight of vinylidene chloride. Under the Textile
Fiber Products Identification Act, any fiber containing 85% or
more vinyl chloride may be labeled Vinyon and this includes
100% PVC fiber. Preferably the carrier fibers are thermoplastic
in nature and excellent results have been achieved with poly-
olefins. The carrier fibers are intertwinedor interlinked withthe base fibers. The carrier fibers add flexural strength to
t~.e mat, and resist separation of the base fibers from the mat
and accordingly make the mat more flexible so that it will
hold together without tearing or breaking despite rough
handling and also when the mold partsclose on
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it to form a product. Both the base fibers and the
carrier fibers are substantially uniformly distributed
throughout the body of the mat. The base fibers prefer-
ably comprise the greater number and the greater weight
of fibers in the mat.
In addition to being mechanically intertwined,
the base and carrier fibers of the mat are also bonded
or adhered to one another where indicated diayrammatically
at 17 in Fig. 4O While a separate bonding agent may be
employed, preferably the carrier fibers themselves serve
this purpose. As s~ated, the carrier fibers are prefer-
ably thermoplastic. During the manufacture of the mat,
the mat is heated sufficiently to soften the thermo-
plastic carrier fibers and render them tacky. Hence,
lS the carrier fibers o the mat retain their fibrous
nature, and are generally recognizable as such, but
heat-seal to one another and to the base fibers to
form connections when the carrier fibers cool. The
base fibers, whether of wood or any other material,
will not signiCicantly soften or otherwise be affected
by the temperature at which the mat is heated to
tackify the thermoplastic material.
In its simplest form, the mat consists only
of the two fibers xeferred to above, namely the base
fibers wh~ch may be any of those previously identified
but preferably are wood, and the carrier fibers which
also may be any of those previously identified but
preferably are thermoplastic such as a polyolefin.
These fibers are mixed together in a blender 40 (Fig.~) by
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any suitable means so that they are uniformly distri
buted throughout the batch. This initial mix may consist
of about 70% to 98% by weight of base fibers and about
2% to 30% by weight of thermoplastic carrier fibers, but
preferably about 8S% by weight of base fibers and about
15% by weight of thermoplastic carrier fibers.
~ rom the blender 40, the mix is passed through
a former 44 which is a device for distributing the mix
on a moving belt 46 in a desired width and thickness to
provide a continuous web 48 of mat material~ The'web
~8 of mat material is transported on the belt through
a curing oven 50 at~a temperature and speed such that
the matexial of the web remains in the oven only long
enou~h to sorten the thermoplastic fibers and make them
' tac~y. Hence the thermoplastic fibers'remain generally
recognizable as fibers but, being tacky, they heat-seal
to the base fibers and to each other to form connections
when the mat cools. The thermoplastic fibers may be
any o those previously identified, but if made of
polyethylene, the oven 50 may, for example be maintained
at a temperature in the ran~e of about 250~. to about
370~. and the web will remain in the oven about one to
three minutes. Temperature of the oven and web speed
will, of course, vary depending upon the thermopia~tic
material employed, ma~ thickness, moisture content and
mat density. The base fibers would not soften or other-
wise be affected except at a substantially higher
temperature or longer dwell time in the oven 50.
I'he web 48 of mat material after it leaves
the oven 50 is transported to a crim~ing device which
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in this case is a paix of crimping rolls 110 which are
cylinders having peripheral grooves extending length-
wise of said cylinders defining ribs between which the
mat material passes. These crimping rolls 110 further
increase the flexibility of the web of mat material,
permitting it to be handled and bent or flexed without
breaking. After leaving the crimping rolls llO, the
web of material may be stored in roll form until ready
for use or it may be immediately cut into individual
mat sections of the type shown in ~ig. 1 by a cutter
109 in Fig. 3.
The proce~sing of the mat upon leaving the
crimping rolls and being cut into sections is complete.
It is essentially dry, containing minimum moisture.
The carrier fibers which are intertwined and interlocked
with the base fibers hold them together and resist
separation of individual base fibers from the body of
the mat. The fibers are adhered or heat-sealed to-
gether by the thermoplastic carrier fibers. Mat sections
shown in Fig. 1 cut from the web 48 of mat material
after it leaves the crimping rolls 110 consist of a
coherent mass which can be stacked, banded together in
packs, compressed, picked up, molded into a produc~,
and in general handled without coming apart or breaking
or tearing.
The mold for forming products 10 in Fig. 2 from
the essentially dry mat has mold parts shaped to the
- desired configuration of the product. The mold may be
operated at a temperature of about 325 F. to 590 F. J at
a pressure of about 200 to 1000 psi. The mold cycle
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time may be as little as one minute or less. Actually,
the temperature, pressure, and time cycle required will
vary depending on the ~inal product requirements. l~he
thermoplastic fibers soften and most, if not all, melt
in the mold. Upon cooling the thermoplastic hardens to
form a finished product which can be self-supporting, that
is capable of holding its shape. The base fibers retain
their fibrous ~orm during molding, neither charring-nor
burning at the temperature of the mold, and impart tensile
strength and stiffness to the product.
Products can be formed by the dry process of
this invention with configurations just as complex and
with bends as sharp and angles of as small radii as by
the wet slurry process; and yet this dry process is
faster and less expensive than the wet slurry process~
The wet slurry process requires substantially greater
energy input than this dry process in order to remove
the great amount of moisture inherent in the wet slurry
process~ The wet slurry process requires special equip~
ment to handle large amounts of water and to clean up
the effluent. Such equipment is not needed in this dry
process. The wet slurry process also requires more than
one mold to make a product, whereas in this dry process
a product is formed from the mat in a single step in a
single mold. Products can be formed by this dry process
with far more difficult and complex shapes than could
be att~ed by dry processes heretofore in use.
The products produced by the dry process o~
this invention have many uses. They may be used, for
example, as decorative trim panels, automotive head-
liners, door panels, instrument panels, center trim
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pillars, package trays, ~onsoles, furniture, luggage,
building materials, packaging, automotive components and
other formed products.
To summarize, the thermoplastic carrier fibers
S are mixed with the base fibers to intertwine with them
to strengthen the mat and hold it intact when compressed
between the mold parts to form a panel or other product.
When the mat is heated in the oven, the carrier fi-ners
become tacky and form a multiplicity of interlocking
connections between fibers. Although the carrier fibers
retain their identity as fibers in the mat, they melt in
the molding of a panel or other product. As the product
cools, the thermoplastic hardens to bind the base fibers
into a molded form which is self-supporting, that is,
stiff enough to retain its shape. It should be understood
that the product may be used alone or as a layer in a
laminated structure in which one or more additional layers
of the same or different material are laminated thereto.
As previously stated, fibers other than wood
and polyethylene may be employed with similar results.
For example, base fibers of glass and carrier fibers of
polypropylene may be mixed in varying percentages. These
when processed as above described may be formed into a
mat from which panels and other products can be made,
change being made in the oven temperature and speed of
travel through the oven as may be necessary to f ackify
the polypropylene fibers sufficiently to effect a heat
sealing together of the fibers, and in the mold temperature,
pressure and time as may be necessary to melt the poly-
propylene and form a finished product. The glass fibers
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have a higher softening point than the polypropylene
fibers and, therefore, will not soften or otherwise be
affected by the oven temperature employed to soften and
tacXify the polypropylene fibers.
Supplementary carrier fibers are sometimes
added to the composition of the mat. Examples of
supplementary carrier fibers are acrylics, modacrylics~
metallics and elastomers including rubbers and urethanes.
These particular supplementary carrier fibers have rela-
tively hiqh heat-resistance and would not normally soften
in the oven, but impart special properties to the mat and
to the product. Thu`s, the acrylics and modacrylics add
softness and suppleness, the elastomers add stretchability
and resilience, and the metallics act as a "heat sink~
Certain of the previously identified carriers which would
normally soften in the oven also add special properties
to the mat and to the product. Thus, polyethylene and
polypropylene impart abrasion resistance and are hydro-
phobic, the polyesters are also hydrophobic, and the
polyamides, particularly nylon, impart high heat resistance
to the mat and to the finished product.
There may also be dispersea throughout the mat
a thermosetting material, such as a phenolic resin. This
resin would not be affected by the oven temperature but
would cure and set in the molding of the finished
product. The purpose of adding the thermosettinq material
would be to enhance the stiffness of the product and make
it less likely to sag or lose its shape while still hot
from the mold and also when subjected to high ambient
temperatures of ultimate use. A suitable mix of m2terials
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might consist of 85% by weight wood fibers,10% by weight
polypropylene carrier fibers and 5% by weight of phenolic
resin.
In addition to thermoplastic carrier fibers,
there are other thermoplastic materials that may be
added to the mix from which the mat i5 formed. The added
material would be dispersed throughout the body of the
mat znd have a softening point approximately the same
as that of the thermoplastic carri~r fibers, or at least
such that it would soften in the oven, to serve as a
bonding agent between the base and carrier fibers. The
use of the added th~rmoplastic material would supplement
the bonding action of the thermoplastic carrier fibers, or
the carrier fibers could be made of some other, perhaps
less expensive, material without the capability of
softening in the oven, in which event the bonding together
of the fibers in the mat and in the finished product would
be effected by the added thermoplastic material. An
example of a less expensive material from which the carrier
fibers might be made is shoddy which is about 35% cotton
and about 65% polyester. A suitable mix with percentaaes
by weight might consist of 85%-87% wood fibers, 5% poly-
ethylene, 3-5% shoddy, and 5% phenolic resin. The oven
temperature employed to make a mat from this mix would
be sufficient to soften the polyethylene but not sufficient
to soften or otherwise ~ffect the fibers.
The mat has been described as something from
which a product can be molded by the application of heat
and/or pressure. Actually, however, the mat itself may
serve as an end produt. As such, the mat may be given
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a predetermined shape as by draping it over a form
immediately after it leaves the oven and while the
thermoplastic fibers are still in a heat-softened condi-
tion and the mat is flexible, so that the mat will assume
S the shape of the form. The thermoplastic fibers form
heat-sealed connections between fibers and upon cooling
harden or set ~o bind the mat into the shape imparted to
it by the form. The mat, when an end product, may be
- used as a filter or as hea~ or sound insulation or
packaging or cushioning material. It may be used alone
or as one layer of a laminated or multi-layer product.
Another layer or layers of the same or different
material miqht extend over an outer surface of the mat
or internally thereof to complete the laminated product.
15The carrier fibers of the mat previously
referred to as having the capability of softening or
tacki~ying in the oven have all been thermoplastic by
nature. However, it is possible to use carrier fibexs
which are thermosetting. For example, carrier fibers
formed of phenolic resin may be mixed with suitable
base fibers selected from those previously listed and
heated in the oven 50 at a sl~itable temperature for an
appropriate period of time to cause the carrier fibers
to cure and set and form bonded connections to the base
fibers~
-Although the tackifying of the carrier fibers
to cause them to form bonded connections with the base
fibers has been described as being carried out by heat-
ing the mat in an oven, and excellent results may be
achieved by this method, it should be understood that
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the carrier fibers can be activated or tackified by other
means such, for example, as by a chemical activating
agent or by radiation curing. Moisture may serve as a
chemical activating agent. Thus, the mat may be passed
throuyh a water vapor chamber instead o~ the oven 50,
so thàt the carrier fibers will soften and become tacky
and seal or bond to the base fibers. Ammonia is another
chemical activating agent that may be employed. Radiation
cur;ng of the carrier fibers to make them tacky may be
effec~ed, for exam~le, by gamma rays, ultra-violet rays
or an electron beam.
