U.S. patent number 3,579,763 [Application Number 04/633,073] was granted by the patent office on 1971-05-25 for method of nonwoven cloth manufacture.
This patent grant is currently assigned to Sommer S. A.. Invention is credited to Francois Noel Sommer.
United States Patent |
3,579,763 |
Sommer |
May 25, 1971 |
METHOD OF NONWOVEN CLOTH MANUFACTURE
Abstract
A process for napped surface nonwoven web of interturned
continuous filaments. Stretchable filaments are employed as
starting material to form a web and various of the filaments are
then forced through the web surface and stretched in the process to
form loops on one surface of the web.
Inventors: |
Sommer; Francois Noel (Paris,
FR) |
Assignee: |
Sommer S. A. (Paris,
FR)
|
Family
ID: |
8607259 |
Appl.
No.: |
04/633,073 |
Filed: |
April 24, 1967 |
Foreign Application Priority Data
Current U.S.
Class: |
28/112 |
Current CPC
Class: |
D04H
11/08 (20130101) |
Current International
Class: |
D04H
11/08 (20060101); D04H 11/00 (20060101); D04h
018/00 () |
Field of
Search: |
;28/4,72.2
;161/67,81,154,169,170 ;156/148 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rimrodt; Louis K.
Claims
I claim:
1. A process for making a nonwoven fabric comprising the steps of:
forming a tangled web of synthetic continuous filaments which are
incompletely stretched and therefore possess a certain capacity for
permanent elongation; driving some of said filaments through said
web so as to form loops which protrude from a surface of said web,
and at the same time stretching said filaments which are driven
through said web, the capacity for initial permanent elongation of
said filaments being chosen according to the depth to which the
filaments are to be driven and the number of loops which it is
desired to form over a given surface area.
2. The process of claim 1 wherein the filaments which form the
loops are completely stretched.
3. The process of claim 1 in which the filaments which form the
loops are extended beyond their breaking point so that the loops
are caused to break at their extremities.
4. The process of claim 1 wherein substantially the same number of
filaments is driven through the web to substantially the same depth
for the formation of each loop.
5. The process of claim 1 in which said filaments driven through
said web substantially protrude from said web.
6. The process of claim 1 wherein before the formation of the
loops, the web is heated to the optimum stretching temperature of
the filaments of the synthetic material under consideration.
7. The process of claim 1 in which after the formation of the
loops, the web is subjected to a humid heat treatment.
8. The process of claim 1 wherein the web of substantially
continuous and tangled filaments is subjected to needling prior to
the formation of the loops.
9. The process of claim 1 in which, in order to form the loops, a
number of filaments driven through the web by penetrating the web
with needles so as to force the filaments through the web.
10. The process of claim 9 wherein the web is passed through a
needle loom so that each loop is subjected several times to the
action of the needles.
11. The process of claim 9 in which the web is passed between a
rotating cylinder provided on its periphery with needles, and a
support surface which is grooved in alignment with the rows of
needles on the cylinder.
12. The process of claim 1 wherein a first web of substantially
continuous incompletely stretched filaments is attached to a second
web of completely stretched filaments and that the assembly is
subjected to a deep needle penetration, the first web being placed
at the side through which the needles enter.
13. The process of claim 1 in which a first web of substantially
continuous incompletely stretched filaments is attached to a second
such web of completely stretched filaments and that the assembly is
subjected to a deep needle penetration, the second web being placed
at the side through which the needles enter.
14. The process of claim 9 in which the face through which the
needles enter the fabric is coated with a mechanically foamed
plastic material which is allowed to gel.
Description
The present invention relates to nonwoven fabrics, formed by a
tangled mass of threads or fibers, having on one of their faces a
tufted, hairy or looped appearance.
It has long been known to make felts of synthetic materials from
tangled fibers or filaments consolidated by various means, of which
the most usual is needling.
There are thus obtained dense felts, relatively flat and firm and
having rough or sometimes fluffy surfaces, which, however, lack the
qualities of softness of fur, for example, or of piled or looped
materials used in the manufacture of carpets.
Numerous processes are known for making nonwoven materials having
such a piled or looped appearance and soft feel. In some methods
there are forced through a suitable support, such as a cloth, felt,
or paper, or a foam of plastic or rubber, continuous threads
forming loops of which the tops can afterwards be cut and torn to
produce hairlike fibers. The thread is stitched through the support
for example by machines called tufting machines. This thread is
expensive however since it must be quite free from faults. Further,
tufting machines have a relatively slow output rate.
In other known processes, there are forced, through a support,
discontinuous fibers providing a fibrous layer, by needling the
fibers through the support. These discontinuous fibers come out of
the surface of the support in the form of tufts of pile and it is
thus the fibrous web itself which produces them. There are
obtained, in this manner, nonwoven needled cloths having a certain
softness. It is even possible to separate, thereafter, the support
and the fibrous web in order to obtain a needled piled felt without
intermediate support.
Finally, it has already been proposed to make a nonwoven piled
material by needling tufts of pile from a "generating" web of
discontinuous fibers through a "foundation" web also formed from
tangled fibers.
The piled felts thus obtained are not very stable, however, because
the fibers having free ends in a tuft of pile easily become
detached from the needled web due to their short length. It is
consequently necessary to subject this kind of article to a
complementary treatment in order to reinforce the adherence of the
tufts of fiber to their generating web.
In order to eliminate this inconvenience it has been proposed to
make piled felts by using instead of discontinuous fibers,
continuous strands or filaments issuing directly from a tangled web
of such fibers.
It is known, in effect, to make ordinary felts, consisting of a
multitude of tangled continuous synthetic filaments previously
stretched in order to provide mechanical resistance, wherein
cohesion is enhanced by needling. It is also known that this
operation engenders a supplementary stretching of the
filaments.
Among the advantages of these sorts of articles, it will be
observed that the formation of a felted web directly from
continuous and previously stretched synthetic threads or filaments
enables the usual operations of crimping or cutting the filaments
to be omitted, these being necessary only when using discontinuous
fibers. Moreover, a felted web of drawn continuous filaments offers
greater resistance to wear, since the filaments have a tearing
resistance clearly superior to that of discontinuous fibers.
However, experience shows that such webs do not lend themselves to
the formation of tufts of filaments issuing from the web itself,
which tufts are for improving the external appearance and hand or
feel of the webs.
This feature can be explained by the fact that the formation of
long tufts by forcing the continuous filaments of a felted web
through the web itself by means of needles requires a deeper
penetration of the needles than in the case of a normal needling
for simply reinforcing the cohesion in a web by orientating certain
filaments perpendicularly to the plane of the latter. The filaments
thus deeply driven break before a satisfactory aesthetic effect is
obtained on the web face from which the needles protrude.
With respect to this prior art, the main object of the present
invention is to provide a new type of product, constituted by a
nonwoven fabric, having the appearance of a carpet or fur, which
can be simply and rapidly made, and combines the qualities of good
mechanical strength, good resistance to wear, an aesthetic
appearance and soft feel.
According to the present invention, a process for making a nonwoven
fabric is characterized in that there is formed a web of synthetic
substantially continuous filaments, incompletely stretched i.e.,
possessing a certain capacity for further permanent elongation, and
very tangled, and in that some of the filaments of this web are
driven through the web itself and at the same time stretched, to
cause them to protrude in the form of loops from one of the faces
of the web, the capacity for initial permanent elongation of the
filaments being chosen according to the depth to which the
filaments are to be driven and the number of loops which it is
desired to produce over a given surface area.
Another aspect of the invention is the realization of a needling
device for penetrating a textile web guided by a movable support,
said device comprising a movable head furnished with needles and a
corresponding supporting surface for the textile web provided with
cavities opposite to the needles, characterized in that the needles
have a shaft with a smooth surface and at least two terminal points
separated by a recess.
A further aspect of the invention in the realization of a nonwoven
fabric having the appearance of a carpet or a fur, composed of at
least one web of tangled substantially continuous synthetic
filaments, characterized in that the filaments of this web are
orientated through the said web and form loops whose length is of
the order of the thickness of the web, on at least one face of the
latter.
It will be seen that in carrying out the invention, an agreeable
effect can be obtained by forcing loops of filaments through the
web from which they extend, without however, neglecting to stretch
as completely as possible the filaments of this web in order that
the finished product may benefit from the favorable mechanical
characteristics normal to stretched filaments.
The following detailed description of the invention is referred to
the accompanying drawings in which:
FIG. 1 is a graph showing the curve of elongation against pull
which can be obtained with a synthetic continuous filament;
FIG. 2 schematically illustrates a thread drawing apparatus;
FIGS. 3 and 4 show a needle according to the invention;
FIGS. 5 and 6 diagrammatically illustrate two variants of the
fabric obtained according to the invention; and
FIGS. 7 and 8 diagrammatically illustrate two articles including a
fabric made in accordance with the invention.
When needling is carried out using barbed needles on any given web
of fibers, the needles produce, in a direction perpendicular to
this web, tufts of fibers on the face of the web from which
protrude the needles as small lumps of fibers. There is obtained in
this way a further considerable tangling of the fibers which
constitute the base web, particularly on the face through which the
needles enter which thus acquires a substantial cohesive strength.
In contrast, the majority of fibers initially in the lower parts of
the web are only slightly subjected to the action of the needles,
and thus do not become as strongly intertangled as the fibers in
the upper surface, of which a large part have been forced to
penetrate through the mass of material. The surface at which the
needles enter is therefore generally much more solid than the exit
surface which has often to be reinforced by impregnations of
plastic materials.
When, for any reason, and particularly aesthetic reasons, it is not
desired to thusly impregnate the needle exit face, one is faced
with a weakness of this face of the material. It has been attempted
to compensate for this weakness by increasing the penetration of
the needles, i.e. by producing tufts or lumps of fibers of greater
volume, but in this case, the fibers which appear in perpendicular
position on the surface, and even outside the surface, easily
become detached because the degree of their attachment to the
material is insufficient.
It could thus be thought that it would be desirable to subject to
penetration by needles a web composed of continuous filaments
instead of discontinuous filaments, the driven-out portions of the
filaments, even from deep within the web, being tightly attached to
the latter by their extensions. Tests have been carried out with
known webs of continuous stretched filaments, but, it has been
found that the action of a strong needle penetration had the effect
of rupturing the filaments before the desired effect was obtained,
these filaments being stretched by the needles beyond their
breaking point.
According to the present invention, it is proposed to drive
filaments of a web of nonstretched, or more exactly incompletely
stretched filaments, through this web, in such a manner as to avoid
breaking of the filaments. Thus, further stretchability of the
thread driven in the form of loops through the web is utilized in
order to avoid reaching the breaking point of the threads. The less
the thread is stretched, the more the loop passing through the web
can be elongated without breaking thereof.
However, in order more precisely to define the invention, it will
be more clearly stated what is intended by the expression
"incompletely stretched."
Synthetic threads such as for example polyamide, polyester, or
polypropilene, have the property, once solidified after the thread
forming operation, of being capable of withstanding, without
rupture but with a modification of their structure, considerable
degree of permanent elongation. This permanent elongation can be
realized up to a limit which is more or less defined, beyond which
the thread is said to be stretched and can hardly be elongated
further and only elastically before breaking. This "stretched"
state, well known by specialists, and which results in an
orientation of the molecules of the product is in general sought
and obtained industrially by an operation called drafting, because
it is this which gives the thread its best mechanical
characteristics.
Several methods enable this state of a synthetic thread coming out
of the spinneret to be determined, such as the study by X-rays of
the molecules, carried out in the laboratory or the examination of
a stress-deformation graph which is used more easily in practice.
This method will be used here in order to characterize the state of
a thread by the permanent elongation to which it can be subjected
before arriving at the stretched state.
The diagram of FIG. 1 represents the elongation up to breaking
point of a synthetic thread coming out of the spinneret as a
function of the tension applied thereto. The tension t is shown as
the ordinate and the length l as the abscissa.
The part ab of the curve corresponds to the stretching phase
proper, i.e. to the permanent deformation of the thread which is
realized under practically constant tension. The part bc
corresponds to an elastic deformation, a property which it is easy
to check by slackening off the tension from the point b': it will
be seen that the relation of deformation to tension is shown by the
straight line b'B. The part cd corresponds to a permanent
deformation preceding the breaking point with destruction of the
connections between the molecules, the diminution in cross section
and breaking of the filament occuring at d.
The capacity for permanent elongation of the filament will be
defined here by the ratio: AB/OB' i.e. the ratio between the
increase in length of the initial filament without tension and the
length of the stretched filament without tension. The determination
of this capacity for permanent elongation is made easy by the
presence of the elastic zone bc; in effect, the pull exerted to
effect stretching can be largely indeterminate provided it is
situated in this zone.
The extend of the variation AB/OB depends essentially on the
polymer and on the manner in which it is stretched. For "nylon 6"
for example, of relative viscosity 2, 8, this value can vary from
0.80 to 0 as a function of the conditions existing when the
filament was made.
Thus, by "incompletely stretched" is meant the state of a filament
of which the capacity for permanent elongation is other than
zero.
The possession of a simple manner of determination of this capacity
for permanent elongation enables the initial value for filaments
used in the manufacture of textile material to be regulated; it is
possible thereafter to determine experimentally to what depth
filaments can be driven through the web in order that a certain
percentage of the filaments have a capacity for permanent
elongation after the operation as close to zero as possible, that
is to say practically stretched.
Many different methods of regulating the initial state of the
filament, i.e., the value of its capacity for permanent elongation
can be used. It is possible, for example, to use well-known
drafting frames, of which the speeds are regulated experimentally
to obtain the desired capacity for permanent elongation.
Such a regulation can also be performed at the outlet if the
spinnerets, where the filament is formed from melted polymer. At
the spinneret outlet the threads are cooled, all the threads of a
same spinneret being drawn at high speed by a takeup machine, or by
a blowing nozzle fed by compressed air. The drawing means are
located at a considerable distance from the spinneret so that the
threads do not stick together in the plastic state, and form what
is called a multiple thread.
The term "spinning ratio" refers to the ratio between the driving
speed of the thread and the speed of flow of liquid polymer though
one of the holes of the spinneret. In practice, the drawing speed
of the thread is always much greater than the flow speed of the
liquid into a hole of the spinneret, and this results in a
considerable narrowing of the thread while it is being drawn in the
plastic state.
This narrowing is accompanied by a modification of the structure as
is shown in the following table resulting from experimental
measurements which illustrate a correlation between the spinning
ratio and the capacity for permanent elongation
However, for a determined diameter of the hole of the spinneret,
the spinning ratio fixes the size or the denier of the thread. The
capacity for permanent elongation cannot, therefore, be completely
regulated by varying the spinning ratio.
In order to diminish the stretching capacity beyond fixed limits
with respect to the thread forming, and independently of the size
of the thread, the latter being the size at point A in FIG. 1, that
is to say without tension on the bobbin or in the receiving can,
the following expedient may be used: a thread stretching device is
placed on the thread between the spinneret 1 and the drawing device
2 placed in a position where the threads 3 of the multiple filament
4 are still hot but no longer sticky, in such a manner as to
perform the stretching under optimum conditions. An example of an
embodiment of this thread stretching device, shown in FIG. 2,
consists of two deflecting pulleys 5 and 6 and an intermediate
pulley 7 to which is applied a braking couple of which the value is
a function of the elongation which it is desired to produce in the
thread between these pulleys and the drawing machine.
For example, in the case of a spinning ratio equal to 56, the
capacity for permanent elongation can be varied by varying the
speed of the stretching device, without changing the final denier
value. By using the ratio V/V1 of the winding speed to the speed of
the pulley 7 of the stretching device, there are obtained
experimentally capacities for permanent elongation specified in the
table hereunder:
When the drawing device is a blowing nozzle, it is possible to
cause the capacity for permanent elongation to vary not only by
means of deflecting rollers whose speed is maintained constant, but
also by regulating the air pressure in the blowing tube in such a
way that it produces an elongation of the thread between the entry
and the exit of the said blowing nozzle.
Example: starting with a spinneret having 200 holes discharging 280
g./m. of polyamide 6, a multiple filament was produced which was
blown in a blowing nozzle fed by compressed air at 6 kg./cm.2 and
placed at 1.80 m. below the spinneret. The speed of the thread at
the exit of the blowing nozzle was in the region of 4.200 m./mn and
the size of the thread discharged without tension about 3 deniers.
The capacity for permanent elongation of the threads of the
multiple filament was 0.080.
Finally, it is possible to make directly at the exit of the
spinneret, a multiple filament collected by a suitable device, and
of which the denier (total and by thread) as well as the capacity
for permanent elongation AB/OB are fixed in advance. Thereafter, in
order to carry out the invention there is formed, with the multiple
filaments of which the capacity for permanent elongation and also
the denier are known, a homogeneous web, having substantially
constant apparent density and thickness and of which all the
elementary filaments are tangled to a very high degree, so as to
give the web a certain coherence.
Methods for forming such a web already exist in both the glass
fiber and artificial textile industries. Generally speaking, these
webs can be obtained from distributors of individual filaments or
multiple filaments discharging the thread onto an endless receiving
table which moves at a speed clearly less than that at which the
thread arrived thereon. Auxiliary devices for blowing air and for
reciprocally driving the distributors transversally with respect to
the receiving table enable the tangling of the threads to be
increased.
All the parameters such as the composition of the multiple threads,
the speed of latter, the speed of the receiving table, the spacing
between the distributing devices are determined experimentally with
a view to obtaining a regular web of material whose weight per
square meter is known in advance.
This web lacks cohesion however, and in order to reinforce the
latter, the web is caused to pass, at the exit of the table on
which it is forced, into a well-known needle loom having barbed
needles. This needling, being of relatively low density and low
depth in order to avoid stretching the threads subjected to the
action of the needles, is principally intended to facilitate the
transport of the said web, or to enable it to be attached to one or
more other webs according to requirements. The presence of a
lubricant or pulverized preparation, at the entrance to the needle
loom facilitates this operation.
According to the invention, an attractive effect is sought by
forcing loops of filaments through this web, without however
neglecting to stretch the filaments of this web as completely as
possible in order to obtain a finished product which benefits from
the excellent mechanical characteristics of stretched
filaments.
To this end, the web is subjected to a very deep needle penetration
which causes the filaments of the web to be driven through the web
itself, and at the same time stretches them.
The portions of the filaments which are pushed by the needling
through the web, will be more stretched than those which remain
implanted in the web. It is, however, possible to provide an
apparatus and a method to carry out this operation wherein such a
high percentage of the filaments are completely stretched.
The web can be subjected to a very deep needling, that is to say in
which the needles largely pass through the other face of the web.
However, if this needling is carried out with known barbed needles,
it only produces rather poor loops in the filaments, with such
loops being of uncertain height and having a very variable number
of strands.
In order to obtain loops of presentable appearance, regularly
formed, it is desirable to always drive the same quantity of
threads through the web, and always to the same depth for a given
adjustment of the machine. For this reason, it is preferable to use
special needles as represented in FIGS. 3 and 4. Each has a shaft 8
having a smooth surface, terminating in two parallel pointed
portions 9 and separated by a recess 10 which pulls the filaments
during its passage through the web and stretches them, the
filaments remaining in the form of loops when the needle is pulled
out. By virtue of these needles, the filaments form loops, which
are all at the same height, and have substantially the same number
of strands.
These needles can be placed in a known needle loom in a single row.
In one embodiment, they have a diameter in the order of 3 mm. and
their distance from axis to axis is in the order of 5 mm., this
distance naturally being variable according to the effect which is
desired.
The supporting plate of the needle loom, that is to say the
apertured plate on which rests the web and which serves to support
it at the moment when the needles of the needling head penetrate
it, can advantageously have, instead of holes opposite each needle,
longitudinally disposed slots, in order to facilitate advancing the
web.
The advancement of the web takes place in steps in a rhythm which
is in step with the movement of the needles and at a rate which is
controlled by a governing roller at the exit of the machine for the
spacing of the rows of loops. In general, the latter is of the same
order as the distance between two neighboring loops of a same
transversal row. Thus for example, the needles were spaced apart
two to the centimeter and the advancement of the machine is
adjusted to 6 mm. at a time.
However, and this applies especially when the distance between two
neighboring rolls is small, it is observed that the operation of
forming a row of loops has a tendency to destroy the preceding row
because of slipping of the filaments in the web. In order to avoid
this phenomenon, in the case in which it is considered a nuisance,
it is advantageous to needle the web with the aid of two or more
transverse rows of aligned needles, the spacing of which
corresponds to the rate of advancement of the needle loom.
Thus, the use of several rows of needles enables not only the
portions of filaments constituting the loops to be stretched, but
also the trapping of those which remain between two loops.
Moreover, when several rows of needles are used, and when it is
desired to make very high loops, it is advantageous to locate the
rows of needles according to the heights which increase in the
direction of the movements of the web, each row thus effecting a
part of the stretching and of the formation of a same loop. There
is obtained in this way a relatively progressive stretching of the
threads.
Another method of forming the loops consists in using a cylinder
provided with needles according to the invention over the whole of
its periphery, and to pass the web between this cylinder and a
counter cylinder having circular channels opposite each row of
needles. This method has the advantage of providing a slow rate of
penetration of the needles into the web, and of ensuring a
progressive and regular stretching of the filaments.
Before commencing the operation of forming the loops, it is
advantageous to heat the web to the optimal stretching temperature,
which temperature depends upon the polymer. Thus, for example, with
polyamide 6, the loops can be formed at a temperature of
120.degree. to 150.degree. C., and this greatly facilitates the
operation of the machine, and provides fuller and more abundant
loops, due to a diminution in the number of broken filaments. This
heating can be effected by infrared radiation or by passage of the
web through a heating tunnel. In certain cases, the penetration of
the needles is facilitated when a lubricating agent is sprayed onto
the web since this favors slipping between the threads, and avoids
thread breakages, as is well-known practice in the needling
technique.
The web 11 thus treated has on one of its faces, thick loops 12 of
which the height can be adjusted within a large range of values,
and which can be clearly greater than 1 cm. (see FIG. 5).
Practically all the filaments are stretched for the reasons
explained above, provided, of course, that the initial capacity for
permanent elongation of the filaments of the web has been
appropriately chosen as a function of the height and spacing of the
loops which it is desired to obtain, this being easy to determine
in an empirical manner.
Moreover, the presence of a zone of elastic deformation after this
zone of permanent deformation allows a certain latitude in the
adjustment for this initial capacity for permanent elongation of
the filaments, so that after penetration by the needles the threads
are stretched or nearly so.
It will be observed, however, that in the present invention, this
capacity for initial permanent elongation has great importance,
particularly for the length of the loops.
Thus, in order to obtain loops having a height of 10 mm. from a web
of 500 grams per square meter of filaments whose capacity for
permanent elongation AB/OB was 0.65, was used. This web was caused
to pass through a needle loom having three rows of needles, each
row having two needles per centimeter of width, the rows being
spaced from one another by 6 mm. The penetration of the needles was
adjusted in such a way that the lowest point of their movement was
situated at 10 mm. below the surface on which the web rested.
Loops having a height of 25 mm. have also been made, from a web of
500 grams per square meter having filaments of which the capacity
for permanent elongation AB/OB was 0.65. This web was passed into a
needle loom having two rows of needles each row having one needle
to the centimeter of width, these rows being spaced one from the
other by 10 mm. The penetration of the needles was adjusted so that
the lowest point of their movement was located at 25 mm. below the
supporting surface of the web.
Moreover, loops having a height of 5 mm. have been made from a web
of 300 grams per square meter having filaments whose capacity for
permanent elongation AB/OB was 0.50. This layer was passed through
a needle loom having two rows of needles each row having two
needles to the centimeter of width and the rows being spaced one
from the other by 6 mm. The penetration of the needles was
regulated so that the lower point of their movement was located at
5 mm. below the surface on which the web rested.
In these three cases, after analyzing the final product it was
observed that at least 80 percent of the filaments had a capacity
for permanent elongation in the neighborhood of zero.
According to an interesting variation of the invention, a capacity
for initial permanent elongation and a needle penetration were
chosen such that the filaments constituting the loops were pulled,
by the penetration of the needles beyond their breaking point;
breakage of the filaments at the top of the loops was thus
provoked, and a carpet with the cut hairs or pile 14 having the
appearance of a velvet was produced. The filaments thus broken in
the loops nevertheless remain very solidly gripped in the web 13
from which they project without any further treatment being
necessary.
For example, a pile carpet was made starting from a web of 300
grams per square meter, constituted by filaments having a capacity
for permanent elongation AB/OB of 0.50. The web was passed through
a needle loom having three rows of needles, each row having two
needles per centimeter of width, the rows being spaced from the
other by 6 mm., and the penetration of the needles being adjusted
so that the lowest point of their movement was located at 22 mm.
below the supporting surface of the web. The finished product had a
pile of an average height of 8 mm.
Everything which has just been described, for continuous filaments
which have not been cut at the spinneret outlet, can be applied to
long fibers adapted for the formation of a large number of loops,
and, for this reason, to act as truly continuous filaments.
In order to define the field of application of the invention, the
meaning of the expression "substantially continuous filaments" must
be extended to include fibers which are very long with respect to
the thickness of the web which they make up.
The fabric resulting from the needling can very advantageously be
treated with moist heat with a view to stabilizing the filaments.
This treatment can be performed during the coloring or printing of
the web, by means of steam or by water under pressure, or even in
the absence of any coloring operation at all, if the filaments were
previously colored throughout their mass. This treatment, whilst
fixing the colorants, also reinforces the cohesiveness of the
fabric by causing the filaments to contract slightly and stabilizes
the crystalline structure of the polymers. The filaments then
acquire a better resistance, in particular in the zones where they
are incompletely stretched.
Nevertheless, if the fabric is intended for heavy duty use, as for
example in floor coverings, it is advantageous to reinforce it and
to improve its dimensional stability with the aid of another web
forming a reinforcement and formed with continuous filaments made
in the same way as those of the fabric that is by previously being
stretched with a ratio AB/OB in the vicinity of zero.
The loops 16 of the web 15 of incompletely stretched filaments are
forced through the web 17 of stretched threads (FIG. 7), after the
two webs have been slightly needled together. It is clearly
possible to carry out this operation continuously with the rest of
the process by causing two series of thread distributors, one fed
by a stretched thread the other by an incompletely stretched
thread, to discharge onto the same receiving table.
By way of example, a carpet of this kind has been made by employing
a web comprising continuous stretched filaments of "nylon 66" of a
weight per square meter of 300 grams, on which there was placed a
web of continuous incompletely stretched filaments of "nylon 66" of
a weight per square meter of 550 grams, the two webs being slightly
needled together and thereafter subjected to a needle penetration
according to the invention, certain filaments of incompletely
stretched thread being forced through the web of stretched
thread.
It is surprising to find that excellent results can also be
obtained by operating on the two webs in the reverse direction,
i.e. by causing the needle to enter, according to the invention,
the web 18 of stretched filaments to cause them to emerge as loops
19 on the opposite face of the web 20 of incompletely stretched
filaments (FIG. 8). The resistance and stability of a carpet
obtained in this way are remarkable.
Finally, for certain applications of such an article composed of
one or several webs, the reverse side is coated with a plastic or
rubber material. In the fabrics according to the invention, the
reverse side is constituted by the entry face of the special
needles described above and, by reason of their substantial
diameter and of their form, these needles left in the web a series
of holes. These holes are so many channels in which the usual
coating materials preferentially engage. If one tries to solidly
fasten these materials to the web, it is observed that they pass
through the fabric by means of these holes and this is clearly
undesirable and does not happen with traditional needle
fabrics.
During the practice of the invention, it was found that it was
advantageous to coat the reverse side side of the carpet with a
mechanically foamed plastisol of polyvinyl chloride. This foam,
obtained by mechanically beating the latex or the plastisol before
coating and gelling is used preferably with other porous materials,
the expansion of which during gelling is caused by a chemical
expanding agent which decomposes under the effect of heat; in
effect a foam formed during heating has the same fault as a
noncellular coating: it finds its way into the channels left by the
passage of the needles, forming hard vertical parts, in the
thickness of the carpet.
On the contrary, the mechanically foamed materials penetrate the
interstices and channels, but subside during gelling without
leaving hard parts in the channels.
The mechanically foamed material can be coated by means of a
scraper or a cylinder and in a single or several applications. If
of sufficient thickness, it constitutes a comfortable undercoat,
which reinforces the dimensional stability of the product and
endows it with an excellent rubbing coefficient, which are
advantageous qualities for a floor covering.
Besides application to carpets, the fabric made according to the
invention can have numerous other applications either alone, or in
composite form, in combination with other webs, or in the form of a
coating. Thus, it can be used for example for making wall
coverings, blankets, household textiles such as fabrics for seats,
or for curtains, clothing textiles for linings or overcoats,
fabrics for slippers, and all other products having the appearance
of a carpet or a fur.
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