U.S. patent number 3,853,651 [Application Number 05/320,843] was granted by the patent office on 1974-12-10 for process for the manufacture of continuous filament nonwoven web.
This patent grant is currently assigned to Rhone-Poulenc-Textile. Invention is credited to Pierre Porte.
United States Patent |
3,853,651 |
Porte |
December 10, 1974 |
PROCESS FOR THE MANUFACTURE OF CONTINUOUS FILAMENT NONWOVEN WEB
Abstract
The process and apparatus for manufacturing spunbonded nonwoven
fabrics is disclosed, wherein continuous filaments of organic
polymers are extruded, stretched to orient same, and then arranged
in fabric form on a moving conveyor. The filaments are arranged or
distributed on the moving conveyor by impact from a deflector
surface, wherein at least that portion of the deflector surface
wherein the filaments are at their maximum width is vibrated. The
spunbonded nonwoven fabrics produced are more homogeneous than
similar fabrics produced without vibrating the deflector surface.
The fabrics are suitable for conventional uses of spunbonded
nonwoven fabrics, such as apparel backing, padding and the
like.
Inventors: |
Porte; Pierre (Lyon,
FR) |
Assignee: |
Rhone-Poulenc-Textile (Paris,
FR)
|
Family
ID: |
9091523 |
Appl.
No.: |
05/320,843 |
Filed: |
January 4, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Jan 4, 1972 [FR] |
|
|
72.00264 |
|
Current U.S.
Class: |
156/73.6;
156/148; 156/181; 156/441; 442/401; 28/107; 156/167; 156/229;
428/910 |
Current CPC
Class: |
D04H
3/11 (20130101); D04H 3/033 (20130101); D04H
3/03 (20130101); D04H 3/037 (20130101); D04H
3/011 (20130101); D04H 3/16 (20130101); D04H
3/105 (20130101); Y10T 442/681 (20150401); Y10S
428/91 (20130101) |
Current International
Class: |
D04H
3/02 (20060101); D04H 3/03 (20060101); B32b
031/16 () |
Field of
Search: |
;28/1SM,72NW,72.2
;161/172,93 ;156/148,73,229,167,181,441 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Whitby; Edward G.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
What is claimed is:
1. In a process for manufacturing spunbonded nonwoven textile
fabrics, said process comprising extruding a plurality of filaments
of a fiber forming polymer, orienting the extruded filaments by
stretching same about 200 to about 400 percent of their original
length, and thereafter distributing the filaments on a receiving
surface by impinging the filaments on a smooth deflector surface,
the improvement comprising vibrating in a substantially vertical
plane at least that portion of the deflector surface where the
plurality of filaments have their greatest width at a vibration
frequency of about 1.67 to 1,000 vibrations per second, and at an
amplitude of about 5 to 30 percent of the length of the vibrating
deflector surface.
2. Process according to claim 1, wherein said portion of the
deflector surface is vibrated at a fibration frequency of at least
eight vibrations per second.
3. Process according to claim 1, wherein only a portion of said
deflector surface is vibrated.
4. Process according to claim 1, wherein the entire deflector
surface is vibrated.
5. Process according to claim 1 wherein said portion of the
deflector surface is vibrated at a vibration frequency of eight -
50 vibrations per second.
6. Process according to claim 1 wherein said filaments are
travelling at a speed of 50 - 130 meters per second at the time of
impinging upon said smooth deflector surface.
7. Process according to claim 1, wherein said polymer is
polyalkylene terephthalate.
8. Process according to claim 7 wherein said polyalkylene
terephthalate is polyethylene terephthalate.
9. Process according to claim 1, wherein a fluid jet is directed at
the point said filaments impinge on said smooth deflector
surface.
10. Process according to claim 1, wherein the filaments which have
been received on said receiving surface are needlepunched.
11. Process according to claim 1 wherein the filaments which have
been received on said receiving surface are calendared.
12. Process according to claim 1 wherein said filaments are
distributed on said receiving surface to produce a fabric having a
weight of 10 - 2,000 g/m.sup.2.
13. Process according to claim 1, wherein that portion of the
smooth deflector surface upon which the filaments impinge is fixed,
and the filaments thereafter pass over a different portion of the
deflector surface, which different portion is vibrated.
Description
BACKGROUND OF THE INVENTION
Spunbonded nonwoven textile fabrics are nonwoven textile fabrics
substantially made of continuous filaments generally randomly
disposed throughout the fabric.
The manufacture of spunbonded nonwoven textile fabrics generally
consists of extruding through a spinneret a melted, or even
dissolved, fiber-forming organic polymer. Depending upon the nature
of the particular polymer involved, the extruded filaments are
generally next oriented by stretching the extruded fiber bundle,
generally by pneumatically stretching the filaments with one or
several compressed air jets. Then, the filament bundle is deposited
in a pre-determined manner on a moving conveyor, with the speed and
the method of feeding the conveyor being regulated to control the
desired thickness and width of the nonwoven fabric, and also to
increase the regularity or homogeneous nature, thereof. After being
deposited on the moving conveyor, the spunbonded fabric is often
subjected to a calendaring step, generally a relatively light
calendaring step, preferably with the application of heat, to
increase the cohesiveness of the final product. Generally this
calendaring step causes some of the basic filaments to be bound to
one another, markedly increasing the unity of the non-woven fabric
product.
As mentioned above, after the textile filaments have been extruded
and stretched, the filaments are deposited on a moving receiving
conveyor. The distribution of the filaments on the conveyor is
normally accomplished with the use of deflector surfaces. The
bundle of filaments is directed upon and impinges the deflector
surface at a certain angle and then, after impingement, moves in a
tangential direction along and off of the deflector surface. The
deflector surfaces are in the form of flat or curved surfaces,
preferably curved surfaces of revolution, which can be either
concave or convex in relation to the direction of travel of the
filaments.
It is known to utilize fixed, flat deflectors to produce relatively
regular textile fabrics, and this involves a relatively simple
design. However, the width of the distributed fibers, as well as
their strength, is often less than desired. The art prefers to use
deflectors which produce a greater filament spread, as such use
permits a decrease in the number of filament extrusion or spinning
positions for a given width of final fabric produced. To achieve a
sufficient filament spread, the art has used deflectors with
complex surfaces, or movable deflectors, either flat or curved,
which lead to greater filament spreads. However, these moveable
deflectors are mechanically relatively complicated, expensive,
difficult to precisely regulate, and relatively untrustworthy.
From the above, it will be appreciated that until now it has not
been possible to obtain in a simple manner elementary spunbonded
fabrics which are strong, regular, and have the desired width.
U.S. Pat. No. 2,736,676 discloses a process for producing sheets or
mats made of strands, yarns, or slivers of various materials,
especially glass strands. The glass strands are extruded,
stretched, and then impinged on a deflector surface. The patent
discloses that the deflector surface may be either flat or curved,
and may be fixed or moveable. The angle of impingement is disclosed
as being between 0.degree. and 90.degree.. The patent discloses,
with relation to FIG. 7 thereof, the use of two air jets, mounted
on opposite sides of the point of impact, to laterally sweep the
strand from the deflector surface, by alternate operation. The
patent also discloses, with relation to FIGS. 8 and 9 thereof, the
use of an air jet operating behind the point of impact to aid in
throwing the deflected strand a further distance from the point of
impact to a receiving conveyor. Another effect of the use of these
air jets is to spiral the filaments, so that the filaments are
deposited on the receiving conveyor in the form of loops. The
process of this patent, however, still suffers the defects of prior
processes mentioned above, namely inadequate width and poor
homogeneity of the resulting product.
U.S. Pat. application Ser. No. 247,874 of Marchadier and Togny,
assigned to the common assignee, filed Apr. 26, 1972, now U.S. Pat.
No. 3,798,100 discloses the use of a fluid jet device operating
upon the point of impact of the filaments on the deflector surface
from a location in front of the point of impact in relation to the
direction of the deflected filaments, and in the same plane as the
axis of the filaments before and after impact with the deflector
surface.
SUMMARY OF THE INVENTION
The process of the present invention involves the use of a
vibrating deflector surface upon which the polymeric filament is
impinged, to produce in a simple way a spunbounded nonwoven textile
fabric having an improved spread or width and improved homogeneity.
At least one bundle of filaments is extruded and stretched by
conventional methods. Then the filaments are distributed upon a
moving receiving conveyor by means of a deflector surface, with at
least that portion of the deflector surface at the point where the
filaments have their maximum width being vibrated. Fluid jets may
be associated with the deflector surface if desired.
DESCRIPTION OF THE INVENTION
Spunbonded nonwoven textile fabrics are manufactured by extruding
filaments of a fiber-forming polymer, orienting the extruded
filaments by stretching, and then distributing the filaments on a
receiving conveyor by impinging the filaments on a smooth deflector
surface. The process of the present invention involves vibrating at
least that portion of the smooth deflector surface where the bundle
of filaments has the maximum spread or width. This area of the
deflector surface is that portion which is nearest the moving
receiving conveyor. The filaments may impact the smooth deflector
surface on a fixed portion of the deflector surface or on a
vibrating portion of the deflector surface, as long as the
filaments are subjected to the vibration step at the aforesaid
point of maximum width on the vibrator surface.
Various types of filaments may be used in the present process of
manufacturing spunbonded nonwoven textile fabrics. The filaments
may be made of fiber-forming inorganic polymers, such as glass,
although preferably the filaments are made of a fiber-forming
organic polymer. Any of the conventional textile fiber-forming
organic polymers may be used, such as cellulose acetate, nylon or
other polyamide, rayon, acrylic, modacrylic and the like. However,
the present process is particularly useful in the production of
polyester spunbonded nonwoven fabrics. Preferably, the polyester is
a polyalkylene terephthalate. When the term "polyalkylene
terephthalate" is used in the present specification, it is to be
understood to apply to polymeric linear terephthalate esters formed
by reacting a glycol of the series
HO(CH.sub.2).sub.n OH
wherein n is an integer of 2 to 10, inclusive, with terephthalic
acid or a lower alkyl ester of terephthalic acid, wherein the alkyl
group contains 1 - 4 carbon atoms, such as, for example, dimethyl
terephthalate. The preparation of polyalkylene terephthalates is
disclosed in U.S. Pat. No. 2,465,319 to Whinfield and Dickson, the
disclosure of which is hereby incorporated by reference. The most
widely used and commercially attractive polyalkylene terephthalate
material is polyethylene terephthalate, which is the most preferred
polymer in the practice of the process of the present invention.
Polyethylene terephthalate is generally produced by an ester
interchange between ethylene glycol and dimethyl terephthalate to
form bis-2-hydroxy ethyl terephthalate monomer, which is
polymerized under reduced pressure and elevated temperature to
polyethylene terephthalate. The fiber-forming polymers are extruded
into continuous textile filaments, generally of about 4 to 70
dtex.
The filaments may be extruded at extrusion rates which are
conventional in the textile field. However, it is preferred that
the impinging fibers be travelling at a speed of about 50 to 130
meters per second at the time of impact with the deflector surface,
and the extrusion rate may be accordingly adjusted.
After extrusion, the filaments are generally stretched by an amount
sufficient to orient the polymer molecules in the filament.
Generally, the stretching will be within the range of about 200 to
about 400 percent, based on the unstretched length of the
filaments. Preferably, the filaments are stretched by pneumatic
means, but other means may be utilized, such as those disclosed in
the aforesaid U.S. Pat. No. 2,736,676, the disclosure of which is
hereby incorporated by reference.
After being stretched, the filaments are directed at the deflector
surface, and impinged on the surface, generally at the aforesaid
speed of about 50 to 130 meters per second. While the angle of
impingement may be from slightly more than 0.degree. up to slightly
less than 90.degree., e.g. 1.degree. to 89.degree., it is preferred
that the angle of impingement be from 10.degree. to 80.degree.,
more preferably 20.degree. to 60.degree..
The deflector surface may be flat or curved, and if a curved
surface is used, it is preferred that the curved surface be a
surface of revolution. The curved surface may be either concave or
convex, and may be either stationary or moveable, as known to the
art. Any of the known deflectors, such as those disclosed in the
aforesaid U.S. Pat. No. 2,736,676, may be used in the practice of
this invention. It is important that the deflector present a smooth
surface in order to prevent any restraint of the filaments and to
prevent any filament impingement that might disturb the regularity
of the deflected filaments. In normal operation, the nature of the
deflector material has no significant influence upon the formation
of the spunbonded nonwoven fabric. However, it is clear that the
material of which the deflector surface is made must have
sufficient strength and resistance to abrasion so that the
impingement of the filaments and the fluid jet will not
deterioriate the surface. Among suitable materials for the
deflector surface may be mentioned soft steel, bronze, glass,
ceramics, and the like.
A fluid jet may be directed to the point of impact of the filaments
with the deflector surface. This fluid jet is conveniently formed
by passing the fluid, preferably a gas, and most preferably
compressed air, under pressure, through a nozzle. The use of a
fluid jet generally allows greater filament speeds to be obtained.
In the case of compressed air, the air is suitably under a pressure
of between about 1 to about 4 bars. The nozzle preferably has a
circular cross-section of a diameter of 0.5 to 5 millimeters,
preferably 1 - 3 millimeters, although the nozzle cross-section can
be of shapes other than circular. For instance, the nozzle may be
in the form of a rectangular or eliptical slot, having its major
axis in the vertical plane defined by the axis of the impinging
filaments and the average axis of the deflected filaments. In any
event, the nozzle cross-sectional area is preferably no larger or
smaller than that of the circular nozzle mentioned above. It should
be understood that the fluid pressure and nozzle areas mentioned
above are not limiting, but are decidedly preferred, as it has been
observed that lower pressures or greater cross-sectional areas
produces an insufficient deflected filament spread, whereas higher
pressures or smaller cross-sectional areas generally adversely
affect the homogeneous nature of the resultant nonwoven fabric
product.
Particularly good results are obtained when the fluid jet acts in a
manner which does not destroy the symmetry of the impacting bundle
of filaments. This is accomplished by having the fluid jet
substantially in the vertical plane which contains the axis of the
impacting filaments and the average axis of the deflected
filaments. The deflected filaments will be on diverging paths, so
that some of the deflected filaments will be in a different
vertical plane than other of the deflected filaments. Therefore, an
average axis must be considered. In addition, the deflected
filaments may be subjected to a sweeping action, e.g., such as that
caused by movement of the deflector surface, and this also must be
considered when determining the average axis of the deflected
filaments. The velocity of the fluid jet should not be so great as
to destroy the filament bundle symmetry.
Preferably, but not necessarily, the fluid jet is a gas, which
generally is chemically inert with respect to the filament. It is,
however, possible to use a gas or other fluid which does react with
the filaments, if such action is desired. Compressed air is
conveniently used as the inert gas, as being efficient and
economical, but other gases may also be used, such as nitrogen,
carbon dioxide, helium and the like, and liquids, such as water,
while not preferred, can be used as well.
The distance from the end of the fluid jet nozzle to the point of
impact of the filaments on the deflector surface will vary
according to the type of fluid, fluid pressure, nozzle size,
diameter and number of filaments, and desired width of the fabric
product. Generally, the nozzle will be located a few centimeters
from the point of impact, but this distance can be as great as a
few decimeters. Generally, the distance will be no greater than 5
decimeters and no less than about 2 centimeters, but preferably the
distance is between 2 and 5 centimeters.
The vibrating deflector results in a better entanglement of the
filaments and improved distribution of the filaments in the fabric,
with the result that more regular, homogeneous fabric can be
produced. The deflector, as mentioned above, may be either fixed or
moveable, and may be of a plane form or curved. The deflector can
be made of any rigid material, including stratified materials,
which have a coefficient of surface friction compatible with the
extruded material. Generally, metals are preferred materials for
the vibrating deflector. If desired, the deflector surface may be
coated with a film of an elastomer or the like, or of a product
having a paper-like characteristic.
The deflector surface, or portion thereof, may be vibrated or
actuated by various known means, including mechanical,
electromagnetic, magnetic, pneumatic, or by resonance. The
vibration can also be accomplished by the incident fluid directed
upon the point of impact of the filaments with the deflector
surface, if such fluid is used.
At least a portion of the deflector surface will be vibrated at a
frequency of about 1.67- 1000 vibrations per second, preferably
about 8 - 50 vibrations per second. The amplitude of the vibrations
varies according to the dimensions of the vibrating deflector
surface, but will generally be within the range of about 5 - 30
percent of the vibrating deflector surface portion length. That is,
for a vibrating part which is 100 mm in length, the amplitude of
the vibrations are generally within the range of 5 - 30 mm at the
deflector extremity.
Obviously, several units each comprising a deflector surface and
associated vibrating means can be mounted side by side to treat a
plurality of filament bundles, with each group of filaments so
treated on each unit forming a portion of the final fabric. This
approach permits the ready production of extremely wide spunbonded
nonwoven fabrics. Using this approach, care must be taken to avoid
the disturbance of one deflected group of filaments by another
group at the time of depositing the filaments on the conveyor. It
is preferred to displace the deflected group of filaments so that
they contact the conveyor in a stepwise manner. This is readily
done by displacing the deflectors so that the planes of the
deflected filaments leaving the deflector surface are parallel, and
the points of impact are aligned along a straight line which is
parallel to the plane of the receiving conveyor. This insures that
the distance travelled by each group of filaments between the point
of impact and the conveyor surface is the same.
After the filaments are deposited on the receiving conveyor, in the
general form of the spun-bonded nonwoven textile fabric, the
deposited filaments are subjected to conventional treatments to
improve the cohesiveness of the nonwoven fabric product. Generally
the use of needlepunching or a relatively light calendaring step is
preferred, although other approaches, such as use of an adhesive,
can also be utilized. For polyalkylene terephthalate filaments, a
calendaring step using a nip pressure of 20 - 50 kilograms per
centimeter and a temperature of 140.degree. - 250.degree.C is
preferred. For needlepunching, the fabric is preferably
needlepunched at a penetration density of about 5 - 500
penetrations per square centimeter, although it will be appreciated
that even greater penetration densitites may be used if desired.
Preferably, the penetration density will be in the range of 20 -
100 penetrations per square centimeter.
The weight of the spunbonded nonwoven fabric produced, for a given
fabric width, can be controlled by varying the speed of the
receiving conveyor and/or the extrusion rate of the filaments. In
the case of polyethylene terephthalate, the fabric weight will
generally be in the range of 10 to 2,000 g/m.sup.2, preferably 10
to 500 grams per square meter, most preferably 80 to 120 grams per
square meter.
The distance between the point of impact of the filament bundle on
the deflector surface and the receiving conveyor can be
conveniently regulated by shifting the conveyor. The weight of the
resulting fabric can be varied by changing the speed of the
receiving conveyor and/or by changing the rate of filament
extrusion. The use of the vibrating deflector allows lightweight
fabrics to be produced having a high degree of regularity. As
mentioned, if very wide fabrics are desired, several units, each
consisting of at least one drawplate, a stretching nozzle, and a
vibrating deflector, can be mounted in a side-by-side relationship,
with each bundle of filaments thus forming a portion of the final
fabric.
Because of the equipment simplicity and adaptability, the vibrating
deflector can be used on any conventional apparatus for
manufacturing spunbonded nonwoven fabrics. The spunbonded fabric
may be either of a natural color or may be colored in the bulk. The
fabric may be used as such or printed, impregnated with pulverized
or liquid adhesives or other products or needlepunched in one or
several layers. The spunbonded fabric may be made of heat-bondable
material or of material which is not heat-bondable. The heat bonds
may be developed on appropriate filaments by thermal treatment. The
spunbonded nonwoven fabric produced by the apparatus and process of
the present invention may be used in applications where prior
spunbonded nonwoven textile fabrics have been used, such as apparel
backing, padding for garments and furniture and the like, for
filters, sound and thermal installation, and in housing and in
public works and buildings.
DESCRIPTION OF THE DRAWINGS
The invention will be more readily understood with reference to the
accompanying drawings, wherein:
FIG. 1 represents a schematic side view of the process of the
present invention,
FIG. 2 represents a front view of a portion of the process depicted
in FIG. 1,
FIG. 3 represents another embodiment of the vibrating deflector
surface, and
FIG. 4 represents yet another embodiment of the vibrating deflector
surface .
In FIGS. 1 and 2, filaments 1 are extruded through a spinneret 2 by
a conventional extruder (not shown) and passed through a stretching
compressed air nozzle 3, wherein the filaments are stretched to
orient same. The filaments discharged from the stretching
compressed air nozzle 3 impact upon the fixed deflector surface
portion 4. A compressed air jet 9 formed by compressed air nozzle 8
is directed at the point of impact of the filaments 1 with the
fixed deflector surface portion 4, and this compressed air jet 9
assists in the spreading of the bundle of filaments. The filaments
passing down the deflector surface pass over vibrating deflector
surface portion 5, wherein the vibration is obtained by means of a
cam 7, having a generally square configuration, driven by motor 6.
The filament bundle continues to open under the influence of the
vibrations, with the filament bundle opening increased and the
filaments somewhat undulated by the action of vibrating surface 5.
Thus, the plane filament bundle is transformed into a
three-dimensional filament bundle 10 which is received in the form
of a spunbonded nonwoven fabric 11 on receiving conveyor 12. The
receiving conveyor 12 has a lower speed than the filament bundle
10. The conveyor 12 may be subjected to a transversal displacement
movement, as can the other equipment mentioned above.
FIG. 3 represents an alternative apparatus for vibrating the
vibrating deflector surface portion. Vibrating deflector surface
portion 32 abuts fixed deflecting surface portion 31. The vibrating
portion 32 is made of ferromagnetic material and is vibrated by
means of electromagnetic means comprising an electromagnetic bar
33, connected to an electrical circuit.
FIG. 4 represents yet another alternative embodiment for vibrating
the vibrating deflector surface portion. The vibrating portion 42
abuts fixed vibrator surface portion 41. Vibrating portion 42 is
vibrated by means of bar 43 actuated by solenoid 44.
EXAMPLES OF THE INVENTION
The invention will be understood more readily by reference to the
following examples; however, these examples are intended to
illustrate the invention and are not to be construed to limit the
scope of the invention. In the following examples, the resistance
to rupture was obtained by the procedure of AFNOR GO7.001 of August
1944. The extension values were obtained according to the
procedures of AFNOR GO7.001 of August 1944 and the tear strengths
were determined according to the procedure of AFNOR GO7.001 of
August 1944.
Example 1
Two parallel bundles of filaments, each bundle having 70 filaments
of 8.8 dtex, of polyethylene terephthalate were extruded through
two spinnerets at a rate of 20 kg/hour per spinneret. The distance
between the axis of the two bundles of filaments discharged from
the two spinnerets was 480 mm.
Each extruded bundle of filaments was then stretched 350 percent of
its original length during passage through a compressed air nozzle
and then passed through an apparatus formed by a rectilinear tube
and a plate located at the extremity of the tube. The plate was a
plane inclined surface cutting across the major axis of the tube at
an angle of 10.degree.. The filaments discharged from the surface
of the plate were received on a fixed vibrating deflector.
The fixed vibrating deflector was a plane deflector having a fixed
glass portion which was 150 mm in length and 100 mm in width.
Between the fixed glass portion and the receiving apron of the
moving conveyor, described hereinafter, and adjacent the fixed
deflector surface, was a vibrating plane deflector portion of
polished bluish steel which was 155 mm in length and 90 mm in width
(the length of the vibrating deflector portion was parallel to the
axis of the moving conveyor). The inclination of the deflector
surface (the two portions thereof were located in the same plane)
in relation to the rectilinear tube was 125.degree. and in relation
to the moving conveyor receiving apron was 80.degree.. The
vibrating deflector portion was actuated, or vibrated, by a motor
driving a square cam having sides 57 mm long. The vibrating
deflector portion was vibrated at 2,000 vibrations per minute,
corresponding to a vibrating frequency of 33.3 vibrations per
second. The extremity of the vibrating portion (furtherest removed
from the fixed portion) and an amplitude of .+-. 10 mm. The
opposite extremity of the vibrating portion (closest to the fixed
portion) did not vibrate and was held in fixed abutting
relationship to the fixed portion.
No deflecting air jets were used in this example.
The filaments discharged from the vibrating portion surface were
received on an inclined apron having an angle of 45.degree. in
relation to the horizontal, of a moving conveyor. A web of 1 meter
in width was obtained from the two bundles of filaments, with the
weight of the fabric varying with respect to the speed of the
moving conveyor as follows:
Conveyor Speed m/min 9.6 6.7 3.35 2.20 Web Weight g/m.sup.2 100 100
200 300
The web was then needle punched on one face with needles 9 cm in
length, each needle having three ridges with three sharp edges,
each disposed in a helixical fashion. The needles penetrated 15 mm,
and the needle punching density was 50 punches per square
centimeter.
The needle punched web having a weight of 200 g/m.sup.2 had the
following mechanical characteristics:
Resistance to rupture Extension Tear Strength
______________________________________ Machine direction (along
length of web) 34 kg 70% 11.7 kg Cross- machine direction (along
width of web) 36 kg 54% 13.5 kg
______________________________________
This example was repeated, except the vibrator was not used. The
resulting web, again of a weight of 200 g/m.sup.2 had the following
characteristics:
Resistance to rupture Extension Tear Strength
______________________________________ Machine direction (along
length of web) 42 kg 60% 15 kg Cross- machine direction (along
width of web) 15 kg 33% 5 kg
______________________________________
It will be noted that a more isotropic web was obtained by use of
the vibrating deflector according to the present invention.
The web obtained with the vibrating deflector could be used as
coating backing, padding underfelt, and the like.
Example 2
Example 1 was repeated, with the distance between the two extruded
bundles of filaments being 720 mm. The fixed deflector was replaced
by a plane deflector having a cyclically oscillating motion around
a vertical axis parallel to the impinging filament bundle,
oscillated at the rate of 60 round trips per minute about its axis
with the total travel spanning an arc of 22.degree..
The vibrating deflector was composed of a glass non-vibrating
deflector portion and a bluish steel vibrating deflector portion.
The latter portion had a thickness of 0.2 mm. The dimensions of the
fixed deflector portion were 150 mm in length and 100 mm in width,
whereas the vibrating deflector portion was 150 mm in length and 90
mm in width. The length of the deflector on the average, or
mid-point, position of oscillation was parallel to the axis of the
receiving apron of the moving conveyor. The deflector made an angle
of 125.degree. with the vertical and was located 20 mm from the
tube/plate apparatus. The distance from the lower edge of the
deflector to the receiving apron was 45 cm. The distance from the
point of impact of the filaments on the deflector to the receiving
apron was 690 mm, with the filaments impacting the deflector at the
center of the fixed portion thereof.
The vibrating portion of the deflector was actuated by
electromagnetic means and had a vibration speed of 1,000 vibrations
per minute, corresponding to a vibration frequency of 16.6 cycles
per second. The extremity of the vibrating portion had an amplitude
of .+-. 12 mm.
The two bundles of deflected filaments were combined to produce a
web of 1.4 meters in weight, whose weight varied with the speed of
the receiving apron conveyor similar to Example 1.
A web having a weight of 200 g/m.sup.2 was needlepunched as in
Example 1, producing a needlepunched web having the following
mechanical characteristics:
Resistance Extension to rupture
______________________________________ Machine direction (along
length of web) 35 kg 72% Cross-machine direction (along width of
web) 37 kg 55% ______________________________________
The coefficient of irregularity of the cloth was 8.2 percent. This
coefficient is determined from variation of weight (in grams per
square meter) calculated from weighing 400 random samples of the
web, having a size of 5 .times. 5 cm.
This example was repeated, except the vibrator was not used,
resulting in a web which had the following physical
characteristics.
______________________________________ Resistance to rupture
Extension ______________________________________ Machine direction
(along length of 29 kg 64% web) Cross-machine direction (along
width of web) 40 kg 59% ______________________________________
The coefficient of irregularity of this second web was 9.8
percent.
It will be appreciated from the above that the web produced
utilizing the vibrating deflector surface was more isotropic and
had improved resistance to rupture in the machine direction. The
resulting web was suitable for use in manufacturing wall
coatings.
Example 3
A web having a weight of 120 g/m.sup.2 was made by extruding six
parallel bundles of polyethylene terephthalate fibers, each bundle
being formed of 60 filaments of 4.4 dtex. Each bundle was extruded
through a separate spinneret at the rate of 9.3 kilograms per hour
per spinneret, and the centers of the spinnerets, were separated by
a distance of 370 mm.
The filaments were stretched 350 percent of their original length
by a compressed air nozzle and then discharged upon a fixed
deflector associated with a compressed air jet. The compressed air
jet was applied at the point of impact of the filaments on the
deflector, at an angle of 35.degree. with the impinging filament
bundle. The air jet was formed by passing compressed air at a
pressure of 3.5 bars through a nozzle having a circular port 3 mm
in diameter, with the end of the nozzle located about 30 mm in
front of the point of impact. The deflector was made with a glass
fixed deflector portion having a length of 150 mm and a width of
100 mm and a vibrating deflector portion (made of stratified glass
and polyester resin, with a glass surface) having a length of 150
mm and a width of 90 mm. The extremity of the vibrating deflector
had an amplitude of .+-. 10 mm, and the vibrating portion was
vibrated at a frequency of 16 cycles per second by electromagnetic
means.
The filaments discharged from the vibrating deflector were passed
to an incline apron at an angle of 45.degree. and moving at a speed
of 4 meters per minute, of a moving conveyor. The inclined apron
was located 45 cm from the extremity of the vibrating deflector
portion.
The resulting web was needlepunched similar to Example 1, and then
had a width of 210 mm and a weight of 120 g/m.sup.2 and the
following characteristics:
Resistance to rupture Extension
______________________________________ Machine direction (along
length of web) 26 kg 65% Cross-machine direction (along width of
web) 31 kg 54% ______________________________________
This web had an irregularity coefficient of 5.5 percent.
When this example was repeated, but without the use of the
vibrator, a web of 120 g/m.sup.2 was obtained which had an
irregularity coefficient of 6.5 percent and the following physical
characteristics.
______________________________________ Resistance to rupture
Extension ______________________________________ Machine direction
(along length of web) 18 kg 50% Cross-machine direction (along
width of web) 37 kg 42% ______________________________________
Thus, the use of the vibrating deflector surface increases the
regularity of the resulting web. The resulting spunbonded nonwoven
fabric product could be utilized in manufacturing light coating
backing or interlining.
* * * * *