Note: Descriptions are shown in the official language in which they were submitted.
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3ACKGROUND OF THE INVENTION
Field Of The_Invention
The present invention concerns non-woven fiber materi-
als, in particular elasticized non-woven fiber materials and
a method of making such materials.
Description Of Related Art
The manufacture of elasticized non-woven ~iber materi-
als by the technique of combining conventional texile fibers
with elasticizeable fibers and heat-treating the fabric to
elasticize the elasticizeable fibers is shown in U.S. Patent
4,426,420 (Likhyani). This patent discloses the preparation
15 of non-woven batts comprising a so-called "hard fiber" and
"potentially elastic" fiber. The hard fibers are described
as comprising any synthetic or natural fiber forming materi-
~ al such as polyesters, polyamides, etc., or natural fibers
;~ such as cotton, silk,~paper, etc. The potentially elastic
fibers are stated to be elastomeric compositions of the type
which are elasticized by heat-treatment. The Likhyani pat-
ent discloses a method for making a so-called "spunlaced"
non-woven fabric wherein a batt composed of at least two
types of staple fibers is sub jected to hydraulic entangle-
ment by fine, high pressure columnar streams of water whichentangle the fibers to provide the spunlaced material. Af-
ter the entanglement, the resultant fabric is heat-treated
to develop elastic characteristics in the elastomeric fi-
bers. The elastomeric filaments are extruded, cold-drawn
and cut to desired fiber length as described in the sole ex-
ample of the patent.
SUMMARY OF THE INVENTION
; 35 In accordance with the present invention there is
provided a method for making a non-woven elasticized fiber
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material which comprises combinin~, blending or inte~ 9
at least one type of textile fiber with at least one ty~:~e o~
uniaxially oriented elasticizeable fiber, bonding the com-
bined fibers to each other to form a web, matrix, sheet or
the like, and heating the resultant web to heat-shrin~ the
oriented fiber which thereby resumes or recovers its elastic
properties. The resultant web thereby exhibits elastomeric
properties.
One aspect of the invention includes combining about
l~ to 50%, preferably 5~ to 35~, by weigh~ of the elasti-
cizeable fiber with about 99% to 50~, preferably 95~ to 65~,
by weight of the textile fiber.
In another aspect of the invention the elasticizeable
fiber comprises an extruded synthetic elastomeric polymer,
and the method includes the steps of cold-drawing an elas-
ticizeable filament to uniaxially orient the filament to
stretch it by at least about 100~, preferably about 100% to
500~, of its initial len~th, then cutting to preform fila-
ments to a desired fiber length. This fiber is combined
with, and bonded to, the textile fiber while the elasticized
fiber is in its oriented condition to form a suitable web.
In accordance with the invention, the resultant web is
heat-shrunk, preferably at a temperature of about 7~C to
200C, to shrink the oriented fiber to about 10~ to 90% of
z5 its elongated length.
Another aspect of the invention includes combining at
least one type of textile fiber, at least one type of melt
blown fiber and at least one type of elasticizeable fiber to
form the fiber material web. In certain aspects of the in-
vention the elasticizeable fiber is selected from the group
;~ consisting o s~yrene-butadiene copolymers, styrene-butadi-
ene-styrene copolymers and polyurethane.
In accordance with the invention, there is also pro-
vided an elasticized non-woven fiber material comprising at
least one type of textile fiber bonded to at least one type
of elastic fiber obtained by heat-treatment of an oriented
preform, the tex~ile fiber being retracted and pleated upon
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heat-shrinking of the preform to elasticize the elastLc ~i-
ber but the textile iber being sufficiently ~ree to extend
to about its original tension level upon being stretched.
The ~iber material may further include at least one type of
melt blown ~iber.
DESCRIPTION OF THE PREFERE~ED EMBODIMENTS
Non-woven fabrics are of course well known in the art
and generally comprise ~ex~ile fibers, which may be of vary-
ing length from very short fibers to very long or substanti-
ally continuous fibers, which have been combined to form a
web or batt of non-woven fabric. As used herein and in the
claims the term "textile fiber~ is intended to broadly in-
clude any fiber which is useful in making a non-woven fa-
bric. Such fibers may be made of synthetic organic polymer-
ic materials, processed natural materials or a combination
thereof. By way of illustration and without limitation,
synthetic polymeric fibers which are useful as textile fi-
bers in the present invention include polyester fibers,polyamide fibers such as nylon, acrylic ~olymer and copoly-
mer fibers, glass fibers, polyolefin fibers such as polyeth-
ylene and polypropylene fibers, cellulosic derivatives such
as rayon, and combined fibers such as fibers of one material
sheathed with a casing of another material. For example,
; polypropylene fibers sheathed with polyethylene are known in
the art. Fibers made from processed natural materials,
i.e., natural fibers, which are useful as textile fibers in
the present invention include, without limitation, cotton,
silk, wool, pulp or paper and the like as well as blends or
combinations of any two or more of the foregoing fibers.
Such textile fibers are usually distinguished in the art
from elastic fibers as the textile fibers generally have
extremely limited elasticity characteristics. That is, they
35 usually would elongate no more than 40%, usually 20~ to 40~
of their initial length before breaking and generally have a
modulus of elasticity in the range of about 18 to 85 grams
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298~9S
per denier, but may be higher.
As used herein and in the claims, the ter~ "elasti-
cizeable Eiber" has reference to those materials, usually
synthetic polymeric elastomeric materials, which (a) can be
extruded into filaments, (b) be drawn, usually at ambient
temperature ~cold-drawn) to elongate, stretch or orient the
filaments, which will retain ~heir stretched condition upon
being relaxed by release of the drawing tension, and (c)
upon bein~ heated to an elevated temperature the tensioned
material will markedly shrink and thereby recover or resume
its elastomeric property. By being "elasticized" it is
meant that the heat-shrunk ibers will be able to be
stretched to all or nearly all of their relaxed, pre-heated
elongated length and return to approximately their heat-
lS shrunk length upon release of the stretching force.Preferably, the stretched filament is cut to desired fiber
length, which length will depend upon such factors as the
particular process employed or the end use of the material.
Prior to elasticization, the elasticizeable fibers can be
air-laid, carded or otherwise formed into non-woven webs in
; substantially the same manner as textile fibers.
By "cold-drawing" as used herein and in the claims is
meant the technique of drawing or stretching the elastomeric
- filament or preform when it has cooled to substantially be-
~- 25 low its extrusion temperature, usually when it has cooled to
ambient temperature. Such drawing is conventionally utiliz-
ed to strengthen and reduce the diameter of the extruded fi-
ber. The cold-drawing as utilized in the present invention
is carried out at a temperature below the extrusion tempera-
ture, pre~erably at ambient temperature, and the cold-draw-
ing is preferably carried out to an extent to elongate the
fiber by about 100% to 500~ or more, e.g., 1,000%, but usu-
; ally about 100% to 400% of its initial length.
In the prac~ice of the present invention, the elasti-
cizeable fiber is combined with the ~extile fiber, and mayoptionally be combined with other materials such as melt
blown fibers, by any suitable technique such as dry-laid,
29~369~
wet-laid or carding techniques and the combined ~i~ers are
then bonded by any suitable technique which will not heat
the elongated elasticizeable fibers so as to shrink them
since, in accordance with the invention, heat-shrinking o~
S the elasticizeable fibers is carried ou~ after they are
bonded to the textile fibers or the textile and melt blown
fibers. Thus, adhesive, e.g., latex spray bonding, sonic
wave bonding, or any combination of suitable techniques may
be employed, so long as the elasticizeable fiber shrinking
temperatures are avoided until the bonding operation is car-
ried out. The result is a shrinkable, that is, a heat-
shrinkable, fiber material in which the shrinking of the
elasticizeable fibers will shrink the web of bonded elasti-
cizeable and textile fibers. A preferred method o~ bonding
is to spray a light coating of any suitable adhesive, such
as a latex, e.g., a urethane latex, onto the web of combined
fibers. ~he fibers may be combined in any suitable way and,
as used herein and in the claims, the term "adhesive" is
; used broadly to mean any material which will bond the com-
bined fibers one ~o the other and is otherwise suitable for
~; the purposes of the invention. The adhesive or sonic bond-
ing is preferred as it physically joins the fibers, not
merely by frictional entanglement, so that the heat-treat-
~ ment to shrink and thereby elasticize the elasticizeable fi-
; ~5 ber relaxes the textile fibers so that they do not impede
stretching of the elasticized fibers. The web of fiber ma-
terial after heat-treatment will be reduced in its length
and width dimensions.
After the combined fibers are bonded together, the re-
sultant fiber material web is heated by any suitable means
such as being passed through an oven, under heating lamps,
infra red radiation, or the like, in order to heat the elas-
ticizeable fibers sufficiently to shrink them to impart the
desired elastic characteristics thereto. The fiber material
containing the elasticizeable fibers is in a relaxed condi-
tion during the heating step to allow contraction.
A significant advantaqe provided by the technique of
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the invention is that inasmuch as the elasticizeable ~ ~ers
are oriented when they are bonded to the textile ~ibe~s,
upon shrinking o~ the fo~mer the textile ~ibers bonced
thereto will retract and loop or pleat as the elasticizea~le
ibers contract. Consequently, when the finished fabric is
stretched, even if it is stretched to a degree which returns
the now elasticized fibers to their original pre-shrunk
length, there is sufficient play in the textile ~ibers that
they do not restrain stretching o~ the fabric. In other
words, maximum stretching o the elas~icized ~ibers, even to
their pre-shrunk length, will extend the textile fibers only
to the tension level they were at when they were bonded to
the unshrunken elasticizeable fibers. This contributes
greatly to the comfort and stretchability of the non-woven
fabric o~ the invention.
The elasticizeable fibers useful in the invention may
be any suitable fiber, as described above. One elasticize-
able fiber ~ound to be useful is sold under the trademark
KRATON by Shell Chemical Company and another is sold under
the trademark ESTANE by B. F. ~x~-ich Company Other suit-
able compositions are those disclosed in U.S. Patents
3,007,227, 3,651,014, 3,766,143, and 3,7b3,109.
; The ESTANE elasticizeable fiber is a urethane poly-
mer and the KRATON elasticizeable fiber is a styrene-butadi-
ene~styrene copolymer.
The following examples illustrate specific embodi-
ments of the invention.
Examole 1
Several grades of urethane elasticizeable polymers
sold under the trademark ESTANE by .B. F. ~x~rich C~ny
and several grades of styrene-butadiene-styrene elasticize-
able polymer sold under the tradema~k ~RATON byShell Chemlcal
Ccmpany were extruded into ~ilaments. The ex~ruder had
~our heat zones along the screw, typically maintained at re-
spective temperatures of 148.9C, 168.3C, 176.7C and
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182.2C in the direction oE extrusion. The die comprised
eight openings of 10 mil diameter each and a die pressure oE
from 3,500 to 5,500 psi was utilized. After cooling to am-
bient temperature, the extruded filaments were cold-drawn
over rollers with the following typical results, dependent
on specific ex~rusion conditions:
TABL~ I
:
10 Elasticizeable
Polymer ~a) ~b) (c) (d)
ESTANE 5707 8,000 122.110.616 308
ESTANE 5710 7,000 135.180.341 254
RRATON 1102 4,600 390.30.19a 1085
KRATON 3200 1,700 139.80.076 268
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(a~ ~ Nominal tensile strength Psr
(b) = Denier per filament
(c) = Tensile strength, grams per denier
(d) = ~ elongation to breakage
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The percentage elongations to breakage show highly elastic
fibers which, after heat treatment, are shrinkable to a
fraction of their elongated length and elastic between ap-
proximately their heat-shrunk and elongated lengths.
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Example 2
A four-ply supercrimp nylon fiber was Eormed into a
30 carded web and stretched, elasticizeable Eibers made of
KRATON 3200 copolymer extruded as described above were air-
laid onto the carded nylon. The elasticizeable fibers had a
denier o 139.8, 0.076 grams per denier and an elongation to
breakage of 268%. The fiber content of the finished web
35 comprised 60% by weight elasticizeable fiber and 40~ by
weight nylon. Upon heating, the web of fiber material show-
ed shrinkage and corresponding elasticity as Eollows:
~Z9~36~5
Heating Temperature ~ Shrinkage o~ Web_
Sample 80C 120 C150C
`~ 1 29 3S 44
2 30 37 45
3 2g 33 43
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Example 3
A bonded web was prepared from 1.5 parts by weight
Enka Rayon 700 1 9/16 inch staple fibers, l.S parts by
weight 1 9/16 inch polypropylene staple fibers and 12 parts
by weight KRATON 3200 elasticizeable fiber of Example 2. A
urethane binder li~uid was sprayed onto the web in a pattern
of nearly touching 1/8 inch diameter dots by use of a spray
template. The urethane binder comprised 80~ by weight of
the finished bonded web. Upon heating at 120-130C, the web
of fiber material sustained 38~ shrinkage.
A bonded web was prepared from ~ parts by weight
polypropylene 1 9/16 inch staple fibers, 9 parts by weight
KRATON 3200 fibers per Example 2 cut to 1 9/16 inch staple
length, and the combined fibers were bonded with a pattern
of five dots of urethane binder so that the finished web
comprised 70% by weight urethane binder. Upon heating to
120-130C, the web of fiber material showed a shrinkage of
65~o
The fiber webs of the invention show excellent elas
; ticity as stretchability unhampered by the limited stretch-
ability of the textile fibers. This follows from the above-
described method of bonding the elasticizeable fibers in
their elongated, pre-shrunk state to the textile fibers in a
shrinkable web.
While the invention has been described in detail with
`~ respect to specific preferred embodiments thereof it will be
appreciated that upon a reading and understanding of the
oregoing variations and modifications to the preferred em-
bodiments will occur to those skilled in the art and such
variations and modifications are believed to fall within the
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spirit and scope ot the .n ~ntion and the appended cldims.
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