U.S. patent number 3,657,035 [Application Number 04/844,153] was granted by the patent office on 1972-04-18 for water absorbent web and its production.
This patent grant is currently assigned to Nylonge Corporation. Invention is credited to Galib-Bey Atam Alibeckoff, Alfred Politzer, Pao-Chi Wang.
United States Patent |
3,657,035 |
Politzer , et al. |
April 18, 1972 |
WATER ABSORBENT WEB AND ITS PRODUCTION
Abstract
A web which is soft and rapidly and highly water absorbent when
both wet and dry is produced by sandwiching under pressure a layer
of cellulose pulp fiber reinforced, foamed viscose between thin
fleeces of unbonded cotton fibers and regenerating the viscose
cellulose. The product is a reticulated matrix of regenerated
cellulose and dispersed pulp fibers with the fleece fibers embedded
in the opposite faces of the regenerated cellulose layer.
Inventors: |
Politzer; Alfred (Fairview
Park, OH), Atam Alibeckoff; Galib-Bey (Lakewood, OH),
Wang; Pao-Chi (Bay Village, OH) |
Assignee: |
Nylonge Corporation (Cleveland,
OH)
|
Family
ID: |
25291958 |
Appl.
No.: |
04/844,153 |
Filed: |
July 23, 1969 |
Current U.S.
Class: |
156/78; 156/298;
536/57; 442/373; 428/317.9 |
Current CPC
Class: |
B32B
5/245 (20130101); D04H 1/593 (20130101); B32B
5/18 (20130101); B32B 37/10 (20130101); A41D
31/125 (20190201); B32B 2432/00 (20130101); Y10T
442/651 (20150401); B32B 2307/726 (20130101); Y10T
156/109 (20150115); B32B 2262/062 (20130101); Y10T
428/249986 (20150401) |
Current International
Class: |
A41D
31/02 (20060101); A41D 31/00 (20060101); D04H
1/58 (20060101); B32b 031/06 (); B32b 023/06 () |
Field of
Search: |
;161/269,151,156,159-161
;156/78,79,62.4,279,280,298 ;260/217,218 ;117/144 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ansher; Harold
Claims
We claim:
1. The method of producing a water absorbent material comprising
forming a viscose foam having a ratio of sodium hydroxide to
cellulose exceeding 0.9:1.0, sandwiching a layer of said viscose
foam under pressure between two layers of randomly distributed
cellulose fibers having an average staple length exceeding 10 mm
and thereafter regenerating the cellulose in said viscose.
2. The method of producing a soft water absorbent product
comprising forming a foamed viscose having an alkalinity
corresponding to a ratio of sodium hydroxide to the cellulose
dissolved in said viscose exceeding 0.9:1.0, laminating a layer of
said foamed viscose between opposing layers of fibers and
regenerating the cellulose in said viscose.
3. The method of claim 2 wherein said viscose foam contains a
surfactant and reinforcing fibers dispersed and undissolved in said
viscose.
4. The method of claim 3 wherein said foamed mixture is produced by
whipping air into a mixture of said viscose, reinforcing fibers and
surfactant.
5. The method of claim 3 wherein said cellulose is regenerated by
exposing said laminate to an acid bath at an elevated
temperature.
6. The method of claim 3 wherein said foamed mixture has a specific
gravity of 0.6 to 0.15.
7. The method of claim 3 comprising depositing a first layer of
randomly oriented cellulose fibers on a substrate, depositing a
layer of said foamed mixture on said first layer, depositing a
second layer of randomly oriented cellulose fibers on said foamed
mixture layer, and then compressing said layers.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to improvements in wiping,
washing and cleaning articles and it relates particularly to an
improved soft, highly water absorbent, web or cloth and to an
improved method for producing the same.
Wiping and cleaning webs are broadly of two types, the paper towel
or napkin type which is generally formed of randomly oriented wood
cellulose fibers in a relatively compact non-woven state produced
on conventional paper producing equipment and the woven or knitted
cloth type which is conventionally formed of cotton fibers. The
conventional wiping and cleaning webs possess numerous drawbacks
and disadvantages which characterize the particular type of web.
Thus, the woven or knitted cotton cloth is generally coarse and
commonly not lint free and are too expensive to be considered
disposable so that for economic reasons they must be regularly
laundered. The paper towel, on the other hand, is likewise coarse,
of low water absorption, and slow water take-up and very weak both
in a dry and wet state. These webs have been treated with polymeric
resins to increase their wet strength but such treatment increases
the cost of the product and reduces its water absorption qualities
and increases its courseness. It is thus clear that the
conventional wiping and cleaning webs leave something to be desired
and generally represent a compromise.
Numerous structures have heretofore been proposed in attempts to
avoid the disadvantages of the conventional cloth and paper webs
but these structures fail to remedy the important defects thereof.
A laminate consisting of two or more tissue paper webs cemented
together by regenerated cellulose derived from intermediate layers
of foamed viscose has been described but this product is relatively
hard and stiff, particularly when dry, and possesses a slow water
take up. It has also been suggested to laminate carded cotton
fleeces with resin foams but the resulting product is of low water
absorption and permeability. Various other composite products have
been proposed which do not satisfy the long felt need for an
inexpensive web of high absorption and rapid take-up of water,
which web is soft and strong when both wet and dry.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide an
improved cleaning and wiping article and an improved method of
producing the same.
Another object of the present invention is to provide an improved
cleaning and wiping cloth and an improved method of producing the
same. Still another object of the present invention is to provide
an improved disposable highly water absorbent cleaning and wiping
cloth which is very soft and possesses rapid water take-up and
great strength both in a wet and dry state.
A further object of the present invention is to provide an article
of the above nature characterized by its low cost, versatility,
convenience of use and attractive appearance.
The above and other objects of the present invention will become
apparent from a reading of the following description.
It has been discovered that a laminate of a reticulated regenerated
cellulose layer and a layer of independently movable cellulose
fibers in which the cellulose fibers at the layer interface are
imbedded in the regenerated cellulose layer possesses numerous
highly desirable characteristics and features. Among these are a
high water absorption capacity, a rapid water take-up and great
softness when wet and dry and a very high wet and dry strength. The
improved article also possesses a high abrasion and wear
resistance, is lint free, inexpensive, so as to be economically
disposable, and possesses numerous other advantages.
In a sense the present invention contemplates the provision of a
highly water absorbent web, sheet or slab material which is soft,
pliable and of high strength when both wet and dry and comprises a
reticulated matrix of regenerated cellulose, preferably containing
cellulose pulp fibers, sandwiched between opposite layers of
non-woven cellulose fibers embedded in the opposite faces of the
regenerated cellulose matrix.
The web or sheet is of a thickness of 0.15 millimeter to 5
millimeters or more with the weight of each of the outer fiber
layers being between 4 to 60 grams per square meter and the outer
fiber layers constitute between 2 percent and 85 percent by weight
of the dry product. The regenerated cellulose constitutes at least
15 percent by weight of the matrix, which may contain cellulose
reinforcing fibers, and advantageously in excess of 20 percent
thereof and preferably constitutes between 15 percent and 95
percent by weight of the dry end product. Where the matrix contains
only a small amount of reinforcing fibers the reticulated matrix
may be to a large extent defined by a highly porous or reticulated
structure and where a large proportion of reinforcing fibers are
employed the matrix may be defined by a three dimensional fiber
network bonded by the regenerated cellulose.
The reinforcing fibers are advantageously of relatively small
staple length preferably averaging between 1.5 mm and 4 mm,
although longer average staple lengths may be employed whereas the
outer fiber layers are advantageously of relatively large staple
length preferably averaging between 10 and 60 mm. Advantageously
the matrix reinforcing fibers are derived from a cellulose pulp,
for example a wood pulp, while the outer layer fibers are
advantageously cotton or rayon fibers which are for the most part
randomly oriented and preferably freely and three dimensionally and
independently interrelated such as of the nature of a fleece or web
of randomly oriented fibers, for example of the nature produced by
the Rando web forming process in the known manner.
The improved method for producing the present product comprises the
steps of forming a foamed preferably fiber reinforced viscose,
sandwiching a layer of the foamed viscose between opposite
cellulose fiber layers, compressing the laminate and thereafter
regenerating the cellulose in the viscose. The foaming is
advantageously primarily effected by admixing the Viscose,
reinforcing fibers and a surfactant and whipping the resultant
mixture to incorporate and disperse air therein and reduce its
specific gravity which is initially about 1.3, to between 0.6 and
0.15. It has been found that the viscose should possess a high
alkalinity as compared to the normal alkalinity of viscose, that is
it should possess a ratio of sodium hydroxide to viscose cellulose
exceeding 0.9:1.0, and an alkalinity corresponding to a ratio of
sodium hydroxide to the viscose cellulose and reinforcing cellulose
fibers exceeding 0.7:10. The viscose cellulose is preferably 2 to
10 percent by weight of the viscose and the alkalinity is between
1.8 percent and 25 percent. The high alkalinity permits the
production of a product with a high proportion of regenerated
cellulose possessing great softness and pliability both wet and
dry.
The laminate of outer fibrous webs and inner viscose foam may be
compressed by passing it between suitably biased squeeze rolls or
between belts or webs which are squeezed together. The compressed
laminate is then passed through a suitable coagulating and
regenerating bath, for example, an aqueous solution containing 10
to 28 percent sodium sulfate and 0.5 to 2.5 percent sulphuric acid,
advantageously at an elevated temperature, preferably between
90.degree. and 100.degree. C to coagulate and regenerate the
viscose and the resulting product is then washed, bleached and
dried. It has been found that the use of high bath temperature
results not only in a greater coagulation and regeneration speed
but also in a softer product of reduced density and other desirable
properties.
Where a relatively thick product is desired it is advantageous to
admix with the foamed viscose sodium sulfate decahydrate crystals.
These crystals may have an average size up to about 1/8 inch and
may constitute up to 8 times the weight of the viscose and the
reinforcing fibers contained therein. Moreover, the improved
product may contain more than two fibrous layers, for example,
three or more, and such product is produced by forming a laminate
of alternate layers of fibrous webs and viscose foam with the
fibrous webs forming the outer layers as well as one or more inner
layers and then proceeding in the manner described above.
A highly advantageous method of forming the laminate of fibrous
outer layers and viscose foam matrix layers is to deposit a first
layer of randomly oriented fibers onto a substrate by means of a
Rondo web forming apparatus, deposit a layer of the foamed viscose
mixture onto the first layer and deposit by means of the Rondo
machine a second layer of randomly oriented cellulose fibers onto
the viscose foam layer. The substrate may be a perforate belt or
screen and the laminate is compressed while being advanced on the
substrate belt by means of an upper superimposed belt or pressure
roller. The foamed viscose layer is of a thickness depending on
that of the desired end product.
The improved product of the present invention possesses an
extremely fast water take-up, a very high water retention, is
highly porous, and is soft and strong in both a dry and wet state
and is lint free and highly abrasion and wear resistant. It is
boilable and launderable, is easily disinfected and sterilized and
may be dyed, printed, sewn, glued, cemented and otherwise treated
and handled. While it is highly suitable as a wiping and wash cloth
it possesses numerous other applications. It is highly useful for
clothing, bed linens, surgical pads, filters, and other
applications and may be impregnated with many active materials.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following examples are given merely by way of illustration of
the present invention.
EXAMPLE I
There was prepared in the conventional manner viscose containing
4.25 percent cellulose, 15.8 percent sodium hydroxide and 1.85
percent sulphur originating in the CS.sub.2 employed in the viscose
preparation. The viscose had a viscosity of 8 seconds as determined
in the known manner with a 1/4 inch steel ball and a 20 centimeter
fall. Two percent by weight of the surfactant dienthanol amine of
capric acid (Nopco GLN) was admixed with the viscose.
Finely divided cellulose pulp fibers are produced by disintegrating
in a hammer mill a 91 percent alpha cellulose bleached Kraft wood
pulp (Buckeye Cellulose E-1). The cellulose fibers possessed the
following screen analysis:
+ 14 48.4% + 28 33.4% + 48 9.9% +100 4.7% -100 3.6%
Ten pounds of the surfactant containing viscose was mixed in a
kneader for 15 minutes to partially foam and increase the volume of
the viscose. Thereafter, 1.25 pounds of the disintegrated pulp was
added to the viscose and the mixing continued for another 45
minutes during which the main foaming occurred and the foamed mass
reached a specific gravity of 0.34.
A first fleece of randomly oriented loose cotton fibers was
deposited in the known manner on a Teflon coated screen, the fleece
having a weight of 15 grams per square meter. A layer of the foamed
viscose mass of a thickness corresponding to about 600 grams per
square meter was uniformly deposited on the first fleece and a
second fleece, similar to the first fleece, was then deposited on
the viscose mass layer. A second Teflon coated screen was deposited
on the viscose fleece laminate and the assembly was advanced
between a pair of rubber coated squeeze rollers at a pressure of
about 30 pounds per square inch.
The squeezed screen and laminate assembly was then directed into a
coagulation and regeneration bath at 100.degree. C and containing 2
percent sulfuric acid and 26 percent sodium sulfate. After
immersion in the bath for three minutes the assembly is removed and
the laminate separated from the screens and subjected to a suitable
after treatment including the steps of desulfurizing, bleaching,
antichlor treatment, washing and drying.
The resulting product was soft when wet or dry and possessed a very
high wet and dry strength and consisted of 18.7 percent regenerated
cellulose, 56.3 pulp fibers, 25 percent cotton fibers and had a
weight of 120 grams per square meter.
EXAMPLE II
The procedure of Example I was followed in which the viscose
contained 6.2 percent cellulose, 7.3 percent sodium hydroxide and
2.7 percent sulfur and had a viscosity of 27 seconds. The foamed
mass contained 2.6 percent of the surfactant and 0.22 pound of the
disintegrated pulp fibers in ten pounds of the viscose. The outer
cotton webs and the viscose mass layer were compressed under four
pounds per square inch pressure. In all other respects the method
of Example I was followed.
The resulting products contained 31.5 percent of the outer cotton
webs, 51.5 percent regenerated cellulose and 17.0 percent pulp
fibers and weighed 95 grams per square meter. It had a wet strength
of 8.8 pounds per inch, a water absorption of 1840 percent and was
soft and supple in both a wet and dry state.
While there have been described preferred embodiments of the
present invention is is apparent that numerous alterations,
omissions and additions may be made without departing from the
spirit thereof.
* * * * *