U.S. patent application number 10/671392 was filed with the patent office on 2004-03-25 for cellulosic substrates with reduced absorbent capacity having the capability to wick liquids.
Invention is credited to Andersen, Birgit, Rearick, William A..
Application Number | 20040058072 10/671392 |
Document ID | / |
Family ID | 22892301 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058072 |
Kind Code |
A1 |
Rearick, William A. ; et
al. |
March 25, 2004 |
Cellulosic substrates with reduced absorbent capacity having the
capability to wick liquids
Abstract
The present invention relates to cellulosic substrates with
reduced absorbent capacity having the capability to wick liquids,
as well as to methods of manufacturing such cellulosic substrates.
The cellulosic substrates provided by the present invention
comprise an inside and an outside connected to the inside. The
inside comprises cellulosic fibers and has a reduced absorbent
capacity, and the outside comprises cellulosic fibers. The outside
may have a reduced absorbent capacity and may have an absorbent
capacity higher than the inside. The cellulosic substrate is
capable of wicking liquid contacting the inside of the substrate to
the outside of the substrate.
Inventors: |
Rearick, William A.; (Cary,
NC) ; Andersen, Birgit; (Raleigh, NC) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
22892301 |
Appl. No.: |
10/671392 |
Filed: |
September 24, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10671392 |
Sep 24, 2003 |
|
|
|
09969293 |
Sep 28, 2001 |
|
|
|
60237090 |
Sep 29, 2000 |
|
|
|
Current U.S.
Class: |
427/324 ;
428/365; 442/79 |
Current CPC
Class: |
B32B 2262/0276 20130101;
Y10T 442/30 20150401; B32B 2555/02 20130101; B32B 5/022 20130101;
Y10T 442/2164 20150401; B32B 27/306 20130101; Y10T 442/3244
20150401; Y10T 442/218 20150401; B32B 5/26 20130101; A61F 13/537
20130101; B32B 27/40 20130101; B32B 2307/726 20130101; Y10T
442/2189 20150401; Y10T 442/419 20150401; Y10T 428/2913 20150115;
Y10T 428/2933 20150115; Y10T 428/249924 20150401; B32B 9/02
20130101; A61F 13/51121 20130101; B32B 27/36 20130101; B32B
2262/0253 20130101; Y10T 442/2221 20150401; B32B 27/32 20130101;
B32B 5/08 20130101; A41D 31/12 20190201; B32B 2262/04 20130101;
B32B 9/045 20130101; A61F 13/51305 20130101; B32B 2262/0292
20130101; B32B 2262/065 20130101; A61F 13/15577 20130101; B32B
2307/73 20130101; A61F 13/512 20130101; Y10T 442/3049 20150401;
B32B 27/34 20130101; Y10T 428/2915 20150115; D04H 1/4374 20130101;
Y10T 428/2965 20150115; B32B 2262/0261 20130101; D04H 1/425
20130101 |
Class at
Publication: |
427/324 ;
442/079; 428/365 |
International
Class: |
B32B 005/02; B32B
027/04; B32B 027/12; B05D 003/00; B05D 003/12; D04H 001/00; D02G
003/00 |
Claims
That which is claimed is:
1. A method of forming a knit or woven fabric comprising the steps
of: (a) providing a first yarn comprising cellulosic fibers, at
least a portion of the cellulosic fibers being treated with a
hydrophobic treatment; (b) providing a second yarn comprising
cellulosic fibers and having a higher absorbent capacity than the
first yarn; (c) forming a fabric having an inside surface and an
outside surface by knitting or weaving the first and second yarns
such that the inside surface has a lower absorbent capacity than
the outside surface, the inside surface has a discontinuous
hydrophobicity, and the fabric has channels of hydrophilic fibers
for wicking liquid contacting the inside surface of the fabric to
the outside surface of the fabric.
2. The method of claim 1 wherein: the first yarn is formed from a
blend of cellulosic fibers treated with a hydrophobic treatment and
cellulosic fibers not treated with a hydrophobic treatment; the
second yarn is formed either from cellulosic fibers not treated
with a hydrophobic treatment or from a blend of cellulosic fibers
treated with a hydrophobic treatment and cellulosic fibers not
treated with a hydrophobic treatment, the ratio of treated fibers
to untreated fibers in the second yarn being lower than the ratio
of treated fibers to untreated fibers in the first yarn; and the
inside surface comprises the first yarn and the outside surface
comprises the second yarn.
3. The method of claim 2 wherein the ratio of treated fibers to
untreated fibers in the first yarn is from 99:1 to 10:90.
4. The method of claim 1 wherein: the first yarn is treated with a
hydrophobic treatment; the second yarn is not treated with a
hydrophobic treatment; the inside surface is formed from the first
and second yarns; the outside surface is formed from the first and
second yarns; and the first yarn is present on the outside surface
of the fabric in a lower amount than on the inside surface of the
fabric or is not present on the outside surface of the fabric.
5. The method of claim 4 wherein the first yam has been subjected
to a discontinuous hydrophobic treatment.
6. The method of claim 4 wherein the ratio of the second yarn to
the first yam on the outside surface is from 99:1 to 10:90.
7. The method of claim 1 wherein the inside surface and the outside
surface consist of cellulosic fibers.
8. The method of claim 1 wherein the cellulosic fibers of the first
and second yams are cotton fibers.
9. The method of claim 1 wherein the cellulosic fibers of the first
and second yams are selected from the group consisting of cotton,
jute, flax, hemp, ramie, iyoceii, rayon, and blends thereof.
10. A method of forming a knit or woven fabric comprising the steps
of: (a) providing a knit or woven fabric having an inside surface
and an outside surface, the fabric comprising one or more yams
formed from cellulosic fibers; and (b) applying a hydrophobic
treatment material to the inside surface of the fabric in a
discontinuous manner such that the inside surface of the fabric has
a lower absorbent capacity than the outside surface, the inside
surface has a discontinuous hydrophobicity, and the fabric has
channels of hydrophilic fibers for wicking liquid contacting the
inside surface of the fabric to the outside surface of the
fabric.
11. The method of claim 10 wherein the inside surface and the
outside surface consist of cellulosic fibers.
12. The method of claim 10 wherein the cellulosic fibers of the one
or more yarns are cotton fibers.
13. The method of claim 10 wherein the hydrophobic treatment
material is selected from the group consisting of silicones,
fluorochemicals, zirconium compounds, oils, latexes, waxes,
crosslinking resins, and blends thereof.
14. The method of claim 10 wherein the cellulosic fibers of the one
or more yarns are selected from the group consisting of cotton,
jute, flax, hemp, ramie, lyocell, rayon, and blends thereof.
15. A method of forming a knit or woven fabric comprising the steps
of: (a) providing a knit or woven fabric having an inside surface
and an outside surface, the fabric comprising one or more yarns
formed from cellulosic fibers, the inside surface having a
discontinuous resist; (b) applying a hydrophobic treatment material
to the inside surface of the fabric in a continuous manner, wherein
the hydrophobic treatment material does not bond to the resist; and
(c) removing the resist from the fabric to form a fabric wherein
the inside surface has a lower absorbent capacity than the outside
surface, the inside surface has a discontinuous hydrophobicity, and
the fabric has channels of hydrophilic fibers for wicking liquid
contacting the inside surface of the fabric to the outside surface
of the fabric.
16. The method of claim 15 wherein the discontinuous resist of the
inside surface of the fabric provided in step (a) is formed by
using one or more yams made from a blend of raw cotton and scoured
or scoured and bleached cotton.
17. The method of claim 15 wherein the discontinuous resist of the
inside surface of the fabric provided in step (a) is formed by
subjecting one or more of the yarns or a portion of one or more of
the yarns used to form the fabric to a resist treatment before the
fabric is formed.
18. The method of claim 15 wherein the discontinuous resist of the
inside surface of the fabric provided in step (a) is formed by
subjecting the inside surface of the fabric to a discontinuous
resist treatment after the fabric is formed.
19. The method of claim 15 wherein the hydrophobic treatment
material is selected from the group consisting of silicones,
fluorochemicals, zirconium compounds, oils, latexes, waxes,
crosslinking resins, and blends thereof.
20. A method of forming a knit or woven fabric comprising the steps
of: (a) providing a knit or woven fabric having an inside surface
and an outside surface, the fabric comprising one or more yarns
formed from cellulosic fibers; (b) applying a hydrophobic treatment
material to the inside surface of the fabric in a continuous manner
such that the inside surface of the fabric has a lower absorbent
capacity than the outside surface; and (c) forming channels of
hydrophilic fibers in the fabric for wicking liquid contacting the
inside surface of the fabric to the outside surface of the fabric
such that the inside surface has a discontinuous hydrophobicty.
21. The method of claim 20 wherein the channels are formed by
needle punching or hydroentangling.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 09/969,293, filed Sep. 28, 2001, which claims the priority
benefit of U.S. Provisional Application No. 60/237,090, filed Sep.
29, 2000. The entire content of U.S. application Ser. No.
09/969,293 and U.S. Provisional Application No. 60/237,090 is
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present application relates to cellulosic substrates
with reduced absorbent capacity capable of wicking liquid as well
as methods of preparing the same.
BACKGROUND OF THE INVENTION
[0003] Cotton is used in many products due to its many desirable
characteristics. For example, cotton is used in absorbent products
due to its high absorbency and is used in wearing apparel due in
part to its many comfort properties (such as, for example, the
natural moisture regain of cotton fibers and the moisture vapor
transport and air permeability/breathability of fabrics made from
cotton). However, some of the properties of cotton make its use
undesirable in certain products.
[0004] For example, cotton has not traditionally been preferred for
use in "recreational performance apparel" primarily due to its high
absorbency. "Recreational performance apparel," as defined herein,
is any apparel that is recommended for use during activities that
may involve perspiration. For any fabric to perform in such
garments, the moisture must be wicked "away from the skin" (i.e.,
the moisture must be transported away from the skin to the outside
of the garment where it is dispersed). The moisture must in fact be
absorbed by the fabric (i.e., pass through the fabric in the Z
direction as well as spread or wick in the X and Y directions)
whereby the outer layer or outside of the garment becomes wet and
evaporation can occur. The same wicking effect must occur in a
layered clothing system when perspiration occurs, as the liquid
moisture must pass from an inside layer to an intermediate or outer
layer whereby it eventually can evaporate.
[0005] The high absorbency of cotton translates into a variety of
problems when used in garments where the consumer undertakes
activities generating moderate or heavy perspiration for prolonged
periods. These problems are that the garment gets too wet and
heavy, sags due to the water weight, takes too long to dry, and
sticks to the skin. Since skin is hydrophilic and the inside of the
cotton fabric is hydrophilic, there is an interfacial/surface
tension which forms at the skin/perspiration interface and at the
fiber/perspiration interface. The interfacial tension combined with
the surface tension of the water or perspiration cause the garment
to stick to the skin when wet. This leads to discomfort and
restricts the freedom of movement, which can be especially bad
during athletic activity. Wet cotton fabrics can also make the
wearer feel cold, especially after exercise or when moving into an
air conditioned environment. The slow drying may allow more time
for odors to build up due to bacterial action on the
perspiration.
[0006] An alternative to using cotton in recreational performance
apparel is to use hydrophobic synthetic fibers in the apparel. A
variety of treatment chemistries are commercially available that
can be used to produce wicking of liquid moisture in normally
hydrophobic thermoplastic synthetic garments. (See, e.g., Reference
paper on wicking finishes by Hodgson Chemical given at the AATCC
Functional Finishes and High Performance Textile Symposium,
University Hilton, Charlotte, N.C., Jan. 27-28, 2000). The wicking
finishes do not penetrate into typical hydrophobic synthetic fibers
such as polyester. They are very hydrophilic and some can absorb up
to 200 times their weight in water. These treatments do allow
wicking of liquid moisture in otherwise non-absorbing fabrics.
Garments made from these treated fabrics have become popular, as
evidenced by products such as very thin polyester T shirts with a
wicking finish.
[0007] The disadvantages of products like polyester shirts with
wicking finishes are that they do not provide the same level of
comfort to the wearer during periods of non-exertion as cotton
garments. Polyester absorbs almost no water within the fiber and
tends to feel clammy when relatively low levels of liquid moisture
are present, because the moisture is present on the surface of the
fibers. In addition, many synthetic garments suffer from odor
retention problems.
[0008] There are also treatment chemistries available that are used
to provide water repellency or other hydrophobic properties to
cotton and/or other hydrophilic fibers. These include, for example,
waxes, silicones, and fluorochemicals. Such chemicals are typically
applied by padding, the goal of which is to saturate and distribute
the chemical finishes uniformly throughout the fabric in all
directions. Tightly woven cotton fabrics treated with such
compounds can be used for raincoats or awnings. However, when used
for recreational performance apparel, perspiration is not wicked
away, but rather collects between the skin and the fabric, which
can be highly uncomfortable to the wearer.
[0009] Synthetic fabrics are also typically preferred over cotton
fabrics for certain recreational performance apparel applications
because most cotton garments (such as t-shirts and running shorts)
that are used for certain athletic activities are relatively thick
and heavy (i.e., the fabrics have a high area density) compared to
many of their synthetic counterparts. The cotton fabrics used in
these garments are thicker than their synthetic counterparts
because of the physical properties of the fibers, filaments, and
the yams used to produce them. The increased thickness of the
cotton garments further aggravates the moisture management issues
because thicker fabrics absorb more moisture (i.e., have a higher
absorbent capacity), get heavier, and take longer to dry. Thicker
fabrics, with other variables held constant, have more internal
capillary spaces which hold liquid than do thinner fabrics.
[0010] Cotton has also not been preferred in some absorbent
products that are worn next to the skin. For example, cotton has
not been preferred in the topsheets of adult and baby diapers and
sanitary napkins. (The topsheet is the part of an absorbent
disposable diaper or sanitary napkin which touches the skin of the
user and which is typically a nonwoven fabric.) Urine or menstrual
fluid must pass through the topsheet and into an absorbent core
where it is trapped. In order to maximize the comfort of the user
of such a product, it is desirable to maximize the wicking of
liquid in the Z direction (i.e., the direction normal to the plane
of the fabric) and away from the skin. The ideal scenario is for
the topsheet to stay dry.
[0011] Polypropylene nonwovens have established themselves as the
most common topsheet material. Although polypropylene is a
relatively inexpensive fiber, it is not widely used in general
wearing apparel that is to be worn next to the skin. This is
because polypropylene is not as comfortable as cotton, because
polypropylene is not readily dyeable, and because polypropylene
adsorbs and holds odors. Furthermore, polypropylene may tend to
exacerbate skin irritation. (See, e.g., Baby Diapers in Y2K--the
challenge for the nonwovens industry continues, Nonwoven Markets,
Oct. 9, 2000, Miller Freeman Inc.)
[0012] Disposable diapers, sanitary napkins, and any absorbent
products that use polypropylene next to the skin are lacking in
basic comfort properties in comparison to products that have cotton
next to the skin. In the dry state (i.e., prior to urination during
use), a topsheet made from regular bleached cotton fiber would
benefit the wearer by providing the many comfort properties of
cotton. However, a topsheet made of 100% regular bleached cotton
would tend to hold too much urine (or menstrual fluid) next to the
skin.
[0013] It would be advantageous to provide products prepared from
cotton or other cellulosic materials which have reduced absorbent
capacity but include wicking properties. The present invention
provides such products as well as methods of manufacturing such
products.
SUMMARY OF THE INVENTION
[0014] The present invention relates to cellulosic substrates with
reduced absorbent capacity having the capability to wick liquids,
as well as to methods of manufacturing such cellulosic substrates.
In one aspect of the present invention, a cellulosic substrate is
provided comprising an inside and an outside connected to the
inside. The inside comprises cellulosic fibers and has a reduced
absorbent capacity, and the outside comprises cellulosic fibers.
The cellulosic substrate is capable of wicking liquid contacting
the inside of the substrate to the outside of the substrate.
[0015] In another aspect of the present invention, an absorbent
product is provided comprising a topsheet and an absorbent core.
The topsheet comprises cellulosic fibers and has a reduced
absorbent capacity. The topsheet also has an inside surface for
contacting a user's skin and an outside surface. The absorbent core
is adjacent to the outside surface of the topsheet and has an
absorbent capacity higher than the topsheet. The absorbent product
is capable of wicking liquid contacting the inside surface of the
topsheet to the core.
[0016] A further aspect of the present invention provides a method
of forming a cellulosic substrate having a reduced absorbent
capacity and capable of wicking liquid. A cellulosic substrate is
provided that has an inside and an outside. A hydrophobic treatment
material is applied to the inside of the substrate in a
discontinuous manner such that the inside of the substrate has an
absorbent capacity lower than the outside and such that the
substrate is capable of wicking liquid contacting the inside of the
substrate to the outside of the substrate.
[0017] Another aspect of the present invention provides an
additional method of forming a cellulosic substrate having a
reduced absorbent capacity and capable of wicking liquid. A
cellulosic substrate is provided having an inside and an outside. A
hydrophobic treatment material is applied to the inside of the
substrate in a continuous manner to reduce the absorbent capacity
of the inside of the substrate. Wicking windows are formed between
the outside and the inside that allow the passage of liquid. The
wicking windows comprise cellulosic fibers from the outside of the
substrate that are capable of wicking liquid contacting the inside
of the substrate to the outside of the substrate.
[0018] An additional aspect of the present invention provides a
method of forming a fabric having a reduced absorbent capacity and
capable of wicking liquid. A first yarn is provided that comprises
cellulosic fibers and has a reduced absorbent capacity. At least a
portion of the cellulosic fibers are treated with a hydrophobic
treatment comprising application of a material selected from the
group consisting of silicones, fluorochemicals, zirconium
compounds, oils, latexes, waxes, crosslinking resins, and blends
thereof. A second yarn is provided that comprises cellulosic fibers
and has a higher absorbent capacity than the first yarn. The first
and second yarns are used to form a fabric that has an inside
surface and an outside surface. The fabric is formed such that the
inside surface has a lower absorbent capacity than the outside
surface and such that the resulting fabric is capable of wicking
liquid from the inside surface of the fabric to the outside surface
of the fabric.
[0019] Yet a further aspect of the present invention provides a
method of forming a nonwoven fabric having a reduced absorbent
capacity and capable of wicking liquid. Cellulosic fibers are
provided that are treated with a hydrophobic treatment and have a
reduced absorbent capacity Cellulosic fibers not treated with a
hydrophobic treatment are provided that have a higher absorbent
capacity than the treated fibers. The treated and untreated
cellulosic fibers are used to form a nonwoven fabric that has an
inside surface and an outside surface. The fabric is formed such
that the inside surface has a reduced absorbent capacity and such
that the resulting fabric is capable of wicking liquid from the
inside surface of the fabric to the outside surface of the fabric.
The fabric is formed by carding, air lay, wet lay, hydroentangling,
thermal bonding, chemical bonding, needle punching, or combinations
thereof.
[0020] Yet another aspect of the present invention provides a
method of processing raw cotton fibers. Raw cotton fibers are
provided that have natural hydrophobic waxes, natural hydrophobic
oils, or combinations thereof. The raw cotton fibers are scoured
with a base. The cotton fibers are also bleached with an oxidizing
agent. The scouring and the bleaching are performed such that all
or a portion of the natural waxes, natural oils, or combinations
thereof are maintained on the resulting cotton fibers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a graph showing the percent wet pickup of water
(wt. percent/gross absorbency) for various treated samples in
Example 1.
[0022] FIG. 2 is a graph showing the percent wet pickup of water
(wt. percent/gross absorbency) for various treated samples in
Example 1 after one home laundering.
[0023] FIG. 3 is a graph showing the percent wet pickup of water
(percent water by wt. percent) for various treated samples in
Example 1, versus control, before and after one home
laundering.
[0024] FIG. 4 is an illustration of a treated fabric placed against
the skin of the wearer showing the path through which perspiration
passes through the inside of the fabric to the outer layer of the
fabric.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention relates to cellulosic substrates with
reduced absorbent capacity having the capability to wick liquids,
as well as to methods of manufacturing such cellulosic substrates.
The invention also relates to methods for reducing the absorbent
capacity of cellulosic fibers, yarns, fabrics, garments, and other
articles having cellulosic fibers.
[0026] According to the present invention, cellulosic fibers such
as cotton may be used in products such as, for example,
recreational performance apparel and topsheets of diapers and
sanitary napkins, to provide the many comfort properties of such
fibers without the disadvantage of the high absorbent capacity and
moisture management problems of such fibers. In such embodiments,
the cellulosic substrate (e.g., garment or absorbent product) is
capable of wicking liquid (e.g., perspiration, urine, menstrual
fluid) away from an inside of the substrate to an outside of the
substrate where it can evaporate (e.g., when the substrate is a
garment) or where it can be stored away from a wearer's body (e.g.,
when the substrate is an absorbent product such as a diaper).
Definitions
[0027] The following definitions are used herein:
[0028] The term "absorbent products" includes products such as, for
example, towels, wipes, "cotton" balls, tampons, sanitary napkins,
adult and baby diapers, medical and dental products including
dental swabs, as well as other items. Absorbent products or
components thereof may be formed from materials such as woven
fabrics, knit fabrics, nonwoven fabrics, and the like.
[0029] The term "cellulosic substrate" as used herein refers to
substrates that include cellulosic fibers such as cotton, jute,
flax, hemp, ramie, lyocell, regenerated unsubstituted wood
celluloses such as rayon, blends thereof, and blends with other
fibrous materials (such as, for example, synthetic fibers) in which
at least about 25 percent, preferably at least about 40 percent of
the fibers are cellulosic materials. The cellulosic fibers
preferably comprise cotton fibers. The cellulosic substrate may
include non-cellulosic fibers (such as synthetic fibers and
non-cellulosic natural fibers) including, for example, a polyolefin
such as polypropylene or polyethylene, polyester, nylon, polyvinyl,
polyurethane, acetate, mineral fibers, silk, wool, polylactic acid
(PLA), or polytrimethyl terephthalate (PTT), and may include
mixtures thereof. In addition, the cellulosic substrate may consist
entirely of cellulosic fibers such as cotton. The substrate may be
any article that contains cellulosic fibers in the requisite
amount, and includes, for example, woven fabrics, knit fabrics,
nonwoven fabrics, multilayer fabrics, garments, yarns, absorbent
products, topsheets of absorbent products, and the like. The
cellulosic substrates of the present invention include substrates
having an "inside" and an "outside." The "inside" of such
cellulosic substrates comprises at least an inside surface of the
substrate and may include all or a portion of the interior of the
substrate. The "outside" of such cellulosic substrates comprises at
least an outside surface of the substrate and may include all or a
portion of the interior of the substrate. Generally, the inside
surface of such cellulosic substrates contacts a user's skin while
in use.
[0030] The term "fabric" includes woven fabrics, knit fabrics,
nonwoven fabrics, multilayer fabrics, and the like.
[0031] The terms "gross absorbency" and "absorbent capacity" are
used interchangeably herein to mean the mass of liquid (e.g.,
perspiration, water, urine, menstrual fluid, etc.) which is picked
up or contained in a fiber, fabric, garment, or other substrate
which is exposed to the liquid under conditions of use. In other
words, the absorbent capacity is the total amount of liquid
moisture which a fiber, fabric, garment, or other substrate will
pick up or hold when in contact with excess liquid moisture from a
wet surface such as skin. More specifically, absorbent capacity is
the mass of liquid per unit mass of fiber, fabric, garment, or
other substrate at saturation.
[0032] The term "reduced absorbent capacity" as used herein means
that the absorbent capacity of the fiber, fabric, cellulosic
substrate, or other article is lower than the normal, standard, or
regular absorbent capacity of the fiber, fabric, cellulosic
substrate, or other article. The term "reduced absorbent capacity"
describes fiber, fabric, cellulosic substrates, or other articles
whose absorbent capacity has been reduced or lowered by methods
described herein to below the normal, standard, or regular
absorbent capacity of the fiber, fabric, cellulosic substrate, or
other article. The term "reduced absorbent capacity" also describes
fiber such as cotton that has been subjected to a modified scouring
and bleaching process as described herein such that the fiber has a
lower absorbent capacity than fiber subjected to a normal scouring
and bleaching process.
[0033] According to the present invention, the absorbent capacity
of the fabric, garment, or other cellulosic substrate is reduced.
There are a variety of commercially available chemical treatments
and yam and fabric construction options to reduce the absorbent
capacity of hydrophilic cellulosic fibers or cellulosic materials
such as cotton. In addition, the normal preparation process of
hydrophilic cellulosic fibers may be modified to produce fibers
with reduced absorbent capacity. A possible consideration when
choosing a chemical treatment, modified preparation process or
construction option from the large number of options is the
durability of the option to home laundering and tumble drying.
[0034] One method to reduce the absorbent capacity of a garment is
to use a thin fabric to make the garment. This is a major factor
for the acceptable performance of many synthetic performance
garments. With other factors held constant, the thinner the fabric,
the less internal void capillary spaces to absorb and hold liquid.
A related method to reduce the absorbent capacity of a garment is
to use finer yams, which allow thinner fabrics to be made. The
yarns may be tightly twisted to further minimize capillary void
volume within the structure of the individual yarn. Further, the
fabric may be made in tight construction while maintaining an
overall thin fabric.
[0035] Another option for preparing garments for use in certain
activities and environments is to make thin but open fabric
structures such as warp knits. Eyelet fabrics can be made by those
of skill in the art which are open, thin, and light weight, but
which are made from yams which have sufficient twist to minimize
the capillary spaces inside the yams. Water or perspiration held in
the fine capillary spaces between fibers in the yarn is held
tightly and therefore more difficult to release. For example, in
more extreme situations of complete saturation of the garment,
perspiration held in the relatively large capillaries which are the
holes in an eyelet warp knit fabric can be readily removed by
shaking the fabric. This loosely held water may even be released
from a fully saturated garment during the natural movement of the
wearer's activity, such as the bouncing or jarring that occurs
during running.
[0036] The absorbent capacity of a fiber, yarn, fabric, garment, or
other cellulosic substrate can also be reduced by chemical
treatments that are used to introduce hydrophobicity into the
fiber, yarn, fabric, or other cellulosic substrate. The chemical
treatments are referred to herein as "hydrophobic treatments" and
include application of any material or materials (referred to
herein as a "hydrophobic treatment chemical") that are capable of
introducing hydrophobicity into a fiber, yam, fabric, garment, or
other substrate. Hydrophobic treatments of the present invention
include application of a hydrophobic treatment material such as,
for example, silicones, fluorochemicals, zirconium compounds, oils,
latexes, waxes and a variety of others including crosslinking
resins such as dimethylol dihydroxy ethylene urea (DMDHEU), urea
formaldehyde, ethylene urea, melamine resins, dimethyl urea glyoxal
(DMUG), carboxylic acids and polycarboxylic acids including citric,
maleic, butane tetra carboxylic, polymaleic acids, and many others.
Blends of these and other hydrophobic treatment materials may also
be used. When manufacturing certain products such as, for example,
recreational performance apparel, according to the present
invention, it may be desirable to choose a treatment chemistry that
is durable to multiple home launderings. In the case of disposable
absorbent products, however, the choice of chemical treatments may
be much broader because durability to home laundering is not
needed. The chemical treatments may be done on fiber, yarn, fabric,
or the completed cellulosic substrate (e.g., garment) or other
article.
[0037] The normal preparation process (i.e., scouring and
bleaching) of cellulosic fiber, such as cotton, that is used to
purify the fiber, whiten the fiber, and make the fiber absorbent
may also be modified to produce fiber with reduced absorbent
capacity. In the normal scouring step of the preparation process, a
base such as a sodium hydroxide solution is first applied to the
fiber at an elevated temperature and pressure to saponify the
natural oils and waxes of the raw fiber and soften impurities in
the raw fiber so that they can be washed away. In the normal
bleaching step of the preparation process, an oxidizing agent such
as hydrogen peroxide or sodium hypochlorite is applied to the fiber
at an elevated temperature and pressure to whiten and further
purify the fiber. The conditions, equipment, and agents used to
carry out the normal scouring and bleaching steps are known to
those skilled in the art. According to the present invention, the
modification of this normal preparation process involves reducing
the concentration of one or both of the base or the oxidizing
agent, replacing the base and/or the oxidizing agents with other
agents, reducing the time of one or both of the scouring or
bleaching steps, and/or reducing the temperature in one or both of
the scouring or bleaching steps. By modifying the normal scouring
and bleaching process, fiber may be produced that is at least
partially purified and bleached without removing all of the natural
waxes and/or oils on the fiber surface (i.e., all or a portion of
the natural waxes and/or oils on the fiber surface are maintained),
such that the resulting fiber has a reduced absorbent capacity as
compared to normal scoured and bleached cotton. The modification of
the present invention may be adjusted as needed to achieve the
desired level of purification and whitening as well as the desired
level of absorbency/hydrophobicity in the resulting fibers. The
resulting fibers may be used in accordance with the present
invention alone or may be blended with normal hydrophilic cotton
(i.e., cotton that has been subjected to the normal scouring and
bleaching process) or other natural or synthetic fibers. Although
the modification of the normal scouring and bleaching process
according to the present invention may leave some natural
particulates in the resulting fiber, the impurities may be
minimized if desired by beginning the process with cleaner raw
cotton or by mechanically cleaning the cotton before or after the
modified process.
[0038] In accordance with the present invention, cellulosic
substrates with reduced absorbent capacity are provided that are
capable of wicking liquid contacting an inside of the substrate to
an outside of the substrate. Several methods may be used in order
to achieve such a cellulosic substrate capable of wicking liquids.
In one preferred aspect of the invention, a hydrophobic treatment
is used, either by subjecting the completed cellulosic substrate to
the hydrophobic treatment or subjecting the material used to
construct the substrate (e.g., cellulosic fibers, yarns, etc.) to
the hydrophobic treatment.
[0039] In some embodiments of the invention (as further described
below), not all of the fiber, yarn, fabric, or other cellulosic
substrate is made highly hydrophobic. In this aspect, the
hydrophobicity of the inside of a cellulosic substrate is made to
be discontinuous in order to allow liquid to be wicked from the
inside to the outside of the substrate through fibers which have
not been made hydrophobic through treatment (i.e., hydrophilic
fibers) remaining on the inside of the substrate. The hydrophilic
fibers on the inside of the substrate form channels that act as
"wicking windows" to allow liquid to move from the inside of the
substrate to the outside.
[0040] In one method, a hydrophobic treatment material may be
applied to a cellulosic substrate (e.g., fabric, garment, topsheet,
etc.) in a discontinuous manner such that (1) the absorbent
capacity of the inside of the substrate is reduced to below the
absorbent capacity of the outside of the substrate and (2) the
substrate is capable of wicking liquid contacting the inside of the
substrate to the outside of the substrate. In another method, a
hydrophobic treatment material is applied to a portion of the
cellulosic fibers used to form the inside of the cellulosic
substrate. For example, a hydrophobic treatment material could be
applied to a portion of the fibers used to form a nonwoven topsheet
of a diaper or sanitary napkin. In yet another method, the inside
of a cellulosic substrate is formed from a yarn comprising a blend
of cellulosic fibers treated with a hydrophobic treatment and
cellulosic fibers not treated with a hydrophobic treatment. In a
further method, the inside of a cellulosic substrate is formed from
at least two yarns where a first yarn is treated with a hydrophobic
treatment and a second yarn is not treated with a hydrophobic
treatment.
[0041] In other embodiments of the invention (as further described
below), the entire inside of a cellulosic substrate is made to be
hydrophobic. The cellulosic substrate could be subjected to a
continuous hydrophobic treatment , or a hydrophobic treatment
material could be applied to the fibers, yarn, or fabric used to
form the cellulosic substrate. Using methods described in more
detail below, channels or "wicking windows" are formed between an
inside of the substrate and an outside of the substrate that allow
liquid to be wicked from the inside to the outside. For example,
wicking windows can be formed in a cellulosic substrate that
includes an inside treated with a continuous hydrophobic treatment
and an outside having hydrophilic fibers by using needle punching
or hydroentangling techniques. Techniques such as needle punching
push hydrophilic cellulosic fibers from the outside of the
substrate through the inside to serve as pathways for wicking
liquid from the inside to the outside of the substrate.
[0042] A range of performance characteristics can be built into a
cellulosic substrate by controlling the amount of treated versus
untreated fibers or yarns which are used to make the substrate, or,
alternatively, by treating only controlled portions of the
completed substrate. These techniques then allow substrates to be
engineered for specific activities, levels of activities, or
combinations of activities and environmental conditions, as well as
personal preferences of the wearer or user of the substrate.
[0043] One means of controlling the amount or ratio of the treated
versus untreated fiber (i.e., the hydrophobic/reduced absorbency
fiber versus the hydrophilic fiber) in a substrate is to perform
the treatment of the hydrophilic fiber (e.g. cotton, rayon, etc.)
on the fiber itself before conversion into yarn, fabric, or other
cellulosic substrate. Both the level of treatment and the blend
ratio of treated versus untreated fiber can be controlled. If
desired, yarn may be spun from 100% treated fiber and a similar or
different yarn may be spun from untreated fiber. The ratio of
treated versus untreated fiber may be varied from 100/0 to 0/100
within any given yarn. Yarns with different ratios of treated
versus untreated fibers may then be used to construct a woven or
knit fabric.
[0044] The woven, knit and nonwoven fabrics of the present
invention can be any area density that is practical from a
manufacturing standpoint. However, fabrics with lower area
densities can be beneficial in some embodiments, as they tend to
lower the gross absorbency of the resulting garments or other
articles of manufacture.
[0045] The fibers, yarns, and other materials with reduced
absorbent capacity according to the present invention can be used
for many purposes, including articles of recreational performance
apparel and absorbent products such as diapers and sanitary
napkins. Raincoats, awnings, yarn, fibers and fabrics, each with a
reduced gross absorption as compared with similar, but untreated
materials, are also within the scope of the invention.
[0046] The following embodiments are described in connection with
applications involving garments and absorbent products. However,
the techniques, yarns, and fabrics described in the embodiments may
also be applied to any other cellulosic substrate or article of
manufacture.
Embodiments Related to Garments
[0047] Embodiment 1:
[0048] Embodiment 1 involves using blends of raw cotton and treated
cotton fiber. A knit, woven, nonwoven fabric, or multilayered
fabric using combinations thereof, can be made from two or more
yarns (or ends). Those skilled in the art of knitting or weaving
can place one yarn (Yarn A) in the fabric primarily on the inside
of the fabric (the side to be worn next to the skin). Yarn A may
contain a certain ratio by weight of treated and untreated fibers,
for example, 70/30 by weight treated (reduced absorbent capacity)
cotton (or other cellulosic) fiber and untreated (normal or natural
absorbent capacity) cotton (or other cellulosic) fiber. A garment
made from this yam (which is the predominant yarn next to the skin)
will have much reduced hydrophilic properties, and the inside of
the garment will also have much reduced hydrophilic properties.
Therefore, Yarn A (and the inside of the garment), having less
affinity for water (or perspiration) will have a much reduced
tendency to stick to the skin during times or activities where
perspiration (liquid) begins to form or later in the activity cycle
if the garment becomes saturated. The reduced tendency to stick to
the skin will increase the freedom of movement, or at least the
perception of freedom of movement. Therefore, the potential
performance and/or the perception of comfort of the wearer is
improved. The untreated portion of the fiber in Yarn A maintains
excellent wicking properties and will pull (liquid) perspiration
away from the skin. The garment will also dry faster because it
will have reduced absorbent capacity.
[0049] A second (or third) yarn (Yarn B) may be used to make this
same woven or knit fabric. Using techniques known by those skilled
in the art of knitting or weaving, Yarn B may be placed
predominantly on the outside of the fabric (that is the side to be
worn on the outside of the garment). Yarn B may also contain a
ratio of treated to untreated fibers, for example, a ratio of 30/70
by weight treated (reduced absorbent capacity) to untreated fiber,
respectively. Since Yarn B is primarily untreated and highly
absorbent (on the outside of the garment) it will tend to wick
(liquid) moisture away from Yarn A on the inside of the garment.
This mass transfer of perspiration away from the interface of the
inside of the garment and the skin will tend to keep the individual
dryer, enhancing the perception of comfort. Since Yarn B is the
predominant yarn on the outside of the garment and is mostly
hydrophilic, the outer surface of the garment will become wet if
the wearer continues to perspire at a sufficient rate. The liquid
moisture in this example is free to spread (wick) over the majority
of the outside of the garment. The pulling of the moisture from the
skin and transporting to the outside of the garment, where the
moisture spreads (by natural capillary movement or wicking) over
the outside of the garment, aids in the perception of comfort. With
the moisture spreading on the outside of the garment, it is
important to increase the surface area which is wet. The more
wetted surface area on the outside of the garment, the more rapid
the overall evaporation rate (i.e. mass of water evaporated per
unit time) since the evaporation rate is dependent on the surface
area exposed to the outside environment (in most situations,
assuming the outside environment is not at 100% relative humidity).
The outside of the garment can be made of completely untreated
fiber or yarn to maximize wicking away from the skin and surface
area for evaporative cooling.
[0050] Any of the yarns that are used in this method, which are
made from blends of treated and untreated cotton, may be intimate
blends or mechanical blends. Intimate blends are made by mixing the
fiber, usually at the opening hoppers. In mechanical blends, the
two fibers are blended in a downstream process such as during
drawing. These alternatives further add options for the engineering
of fabric and garments for specific end use activities,
environmental conditions, or personal preferences.
[0051] Another option is to begin with one or more yams in a fabric
that includes a blend of raw cotton and scoured cotton (or scoured
and bleached cotton); or scoured cotton which has been dyed (stock
dyed). Here, the blends of these two cottons can be used at the
ratios stated above or at any ratio desired by the fabric or
garment designer. The objective is to achieve reduced absorbent
capacity in the fabric, while maintaining the natural wicking,
breathability, moisture regain, moisture vapor transport, softness
and the other desirable properties of cotton for use in clothing.
In this case, the hydrophobic chemical treatments may be done on
fabric using any of the normal equipment and processing routes for
fabric. However, it is preferred that no scouring, washing or
excessive wet processing is done to the fabric prior to application
of the hydrophobic treatment to the fabric. Such wet processing may
tend to remove the natural oils and waxes which coat the raw cotton
fiber in the blend. The natural oils and waxes on the raw cotton
can serve as a "resist" treatment. When the hydrophobic treatment
is applied to the fabric it will preferentially deposit on the
absorbent scoured or scoured and bleached (or dyed) fiber in the
yam. After application of the hydrophobic treatment, the fabric is
then preferably subjected to a drying and curing process specific
for fixing or curing the specific treatment.
[0052] As an example, a crosslinkable hydrophobic water and oil
repellent fluorochemicals such as Repearl F-35 (concentrated
fluorochemical water and oil repellent finish) may be applied to
the fabric with the recommended crosslinking agent, Repearl MF (a
blocked isocyanate reactive cross-linking finishing agent). The
treated fabric may be dried at about 110.degree. C. for 1 to 3
minutes and then cured at 160.degree. C. for 2 minutes. Any of the
Repearl F-35 and MF which may deposit on the raw cotton portion of
the blend of raw cotton and scoured, bleached or dyed cotton, will
be blocked from cross-linking with the raw cotton by the layer of
natural cotton oils and waxes which are present on the cotton
fiber. The Repearl products can be removed from the raw cotton
portion of the blend in a subsequent scouring operation. In this
example, a variety of dye shades can be produced by starting with
stock dyed cotton rather than scoured only or scoured and bleached
cotton, to be blended with the raw cotton. Since the outside of the
garment is predominately made from such dyed fiber rather than raw
cotton, dark shades will be possible. Another option is to dye the
fabric, since the side to be worn on the outside of the garment
will be predominantly regular hydrophilic (absorbent) cotton which
will take dyes. Optionally, in place of the scoured or scoured and
bleached cotton, raw cotton or scoured or scoured and bleached
cotton with a resist treatment may be used.
[0053] Advantages: The treated garment maintains the benefits of
evaporative cooling because the liquid moisture is free to spread
on the outside of the garment, where the amount of wetted surface
area on the outside of the garment will be a major influence on
evaporation rate. Second, the garment will have less tendency to
stick to the skin and restrict movement. Third, the overall
absorbent capacity of the garment is much reduced in comparison to
100% untreated cotton by including cotton (and/or other hydrophilic
fibers) which has been treated to reduce its absorbent capacity.
This reduction in overall absorbent capacity of the garment means
that the garment will not become as heavy as a 100% untreated
cotton garment as the garment becomes saturated. The reduced weight
of the (wet) garment translates into improved performance of the
wearer or at least the perception of improved performance as well
as a further improvement in the perception of comfort. Fourth, the
reduced absorbent capacity of the garment translates into less
sagging of the garment. Fifth, the garment will dry faster than
100% untreated cotton. The time required for a wet garment to dry
depends on the amount of liquid contained in the garment. As the
garment reaches saturation, this amount of liquid is equal to the
absorbent capacity of the garment. If the wearer leaves on the wet
garment described in this example after exercise or activity, there
will be less tendency for the individual to become chilled relative
to a pure untreated cotton garment. After exercise or completion of
whatever activity cause the perspiration, the body temperature
begins to drop back to the resting temperature and because the
garment contains less moisture, there will be less evaporative
cooling. The layer of fiber or yarn which is next to the skin is
primarily treated so that it has much reduced absorbent capacity
and stays relatively dry. This relatively dry layer next to the
skin further reduces the discomfort of a cold wet fabric next to
the skin, when the wearer may become chilled if the outside (or
indoor) environment is cool or cold. The relatively dry layer of
fiber or yarn next to the skin serves to insulate the skin from the
relatively wet and potentially cold outside of the garment. That
is, the transfer of body heat through the relatively dry layer
(inside layer) which is next to the skin is reduced in comparison
to the heat transfer through a wet fabric. If the garment is taken
off and allowed to air dry or machine dry, it will dry faster and
with less energy.
[0054] Examples of treatments for reducing the absorbent capacity
of hydrophilic fibers, yarns, fabrics or garment include
application of fluorocarbons (e.g., Teflon.RTM. brand, Repearl.RTM.
brand, Nuva.RTM. brand, etc.) that do not adversely affect cotton's
beneficial properties, for example, the comfort properties during
"normal" wearing when the wearer and the garment are in the dry
state without significant perspiration. Fluorocarbon treatments can
make cotton very hydrophobic. Such treatments can be used in the
above example or in the practice of this invention in general.
These treatments (e.g., fluorocarbons and silicones) can be applied
to cotton without reducing the natural moisture regain, natural
moisture vapor transport or the natural breathability of cotton
fabrics and garments. Therefore, when performance garments are made
as described in these examples, the basic comfort properties of
cotton that are present during "normal" (dry) wearing of regular
(untreated) cotton garments will also be present in garments
containing treated fiber, yarn or fabric.
[0055] Synthetic fibers such as polyester and polypropylene have
very low moisture regains. Moisture vapor is given off by the body
of an average human subject at rest at a rate of about 1/4 cup per
hour. The rate of moisture vapor given off by the body can increase
substantially as the rate of activity increases. On synthetic
fibers which are inherently hydrophobic (such as polyester and
polypropylene), this moisture vapor can quickly condense on the
fibers as liquid water and make the garment feel clammy which can
have a significant negative impact on the perception of comfort by
the wearer. However, even cotton which has been completely treated
(e.g. in fabric form by padding) with fluorocarbons has been found
to maintain the normal moisture regain of untreated (regular)
cotton which is about 7.5% under standard conditions. As the
relative humidity increases in the microclimate between the garment
and the skin, and in the thin boundary layer of air on the outside
of the garment, the moisture regain of cotton increases for both
treated (using treatments which make the cotton hydrophobic such as
fluorocarbon) and untreated cotton. Hence the cotton can adsorb
more moisture from this microclimate before any liquid moisture is
present. This means that even for treated cotton, or the blends of
treated and untreated cotton, cited in these examples, the onset of
the presence of liquid moisture will occur later in the exercise or
activity cycle. Therefore, the perception of staying dry (and not
clammy) is maintained for a longer period of time, which translates
into increased comfort.
[0056] Hydrophobic treatments such as application of fluorocarbons,
silicones, and waxes are generally thought to function by forming a
film on the outside of the fibers. At normal application levels
this film is highly discontinuous, to the extent of being closer to
microscopic "globs" of polymer or wax on the surface of the
hydrophilic fibers. The treatments do produce hydrophobic fibers,
fabrics and yams from those which were previously hydrophilic
because the surface tension of water or perspiration generally does
not allow the penetration of liquid into the fibers and reduces
wicking in the capillaries formed between treated fibers or
yarns.
[0057] A further advantage of using blends of treated and untreated
fiber (such as cotton) to make yarns for recreational performance
apparel is that the uniformity of treatment is not critical since
the blending operation prior to yarn making, will tend to "even
out" any nonuniformity in the treatment chemistry. It will be
possible to make heathers by dyeing yarn, fabric or garments made
from blends of treated and untreated fiber. If solid shades are
desired, then it may be necessary to stock dye prior to the
finishing treatments to make a portion of the fiber hydrophobic as
described above. Dyeing is preferably done prior to such finishing
treatments regardless of whether the treatments are done on fiber,
fabric, yarn or garments. It is noted that in embodiments where the
outside of the fabric or garment is completely untreated, there
will be little or no impact on the dyed appearance of the outside
of the fabric or garment.
[0058] In this embodiment, the ratio of treated fiber to untreated
fiber in Yarn A may range from 99/1 to 10/90. The preferred ratio
is from about 90/10 to about 20/80.
[0059] Embodiment 2:
[0060] Embodiment 2 involves using yarn treatments. Equipment to
treat fiber is not as widely available as equipment that is used to
treat yarn. When fiber such as cotton is wet processed the
spinnability must be considered and often a spin finish must be
added. In embodiment 1, since each of the yarns contains some
untreated cotton fiber, the untreated cotton can serve as a
"carrier" for the treated cotton and therefore reduce the demands
on a spin finish or in some cases it may eliminate the need for a
spin finish. Another option is to treat yarn.
[0061] In this embodiment, a 100% cotton (or other cellulosic
fiber) fabric is made from two (2) or more yarns. Yarn A can be
treated to increase its hydrophobicity using the same chemistry
described in embodiment 1. Yarn B is untreated cotton (and/or
another cellulosic material or a blend thereof, optionally with a
non-cellulosic material). Those skilled in the art of knitting or
weaving can make fabrics which include Yarn A predominantly on the
inside of the garment and Yarn B predominantly on the outside of
the garment. The fabric can be made in such a way that the highly
absorbent yarn B may vary as a fraction of the surface area of the
inside of the fabric or garment. For example, the inside surface of
the garment may be 70% treated Yarn A and 30% untreated Yarn B. The
advantages listed above in embodiment 1 also apply to embodiment
2.
[0062] Making the new class of recreational performance apparel
from 100% cotton or other yams using a blend of treated and
untreated yam rather than a blend of treated and untreated fiber
provides somewhat less versatility for the designer. Our laboratory
work has shown that varying the level of treatment typically will
affect the hydrophobicity of the treated substrate (fiber, yam
fabric, or garment) only to a limited extent. The level of
treatment can have a major influence on the durability of the
treatments to operations such as home laundering. Choosing
hydrophobic treatments such as Repearl.RTM.F35 combined with
crosslinking compound Repearl.RTM.MF brand (Mitsubishi Chemical)
fluorochemicals can allow treatments which are durable to many home
launderings. Treatments are available which permanently crosslink
to cotton and other cellulosic materials.
[0063] Optionally, resist treatments can be applied on a portion of
the yarn that will form the garment. A resist is a substance that
will prevent a subsequent treatment (e.g., a hydrophobic treatment
to reduce absorbent capacity) from penetrating or forming a
permanent bond with the substrate or portion of the substrate to
which it was applied.
[0064] For example, a recreational performance garment may be made
from two or more yarns, including Yam A and Yam B. Yam A and Yam B
can both be made from 100% cotton and/or other hydrophilic fiber.
Yarn A and B can both be scoured, bleached, and dyed to the same
shade or completely different colors. At the end of the respective
dye cycles for each of the yams, a resist treatment can be given to
Yam B but not to Yam A prior to drying the yams. The resist
treatment can include a variety of treatments known to those who
are skilled in the art of resist printing. For example, treatments
may be used which are appropriate to prevent a fluorocarbon or
other durable water repellent treatment (i.e. hydrophobic
treatment) from bonding to the surface of the fibers which include
Yarn B. A woven or knit fabric can be made from Yam A and Yarn B.
Other yams can be included if desired but for the purpose of this
example, the fabric will be made only from Yam A and B. Those
skilled in the art of weaving or knitting can place the yams in the
woven or knit fabric in such a way that Yam B is predominantly on
the face of the fabric which is the side to be made into the
outside of the garment. The ratio of the surface area on the
outside of the garment which has Yam B exposed, relative to the
surface area which has Yam A exposed, can be engineered by the
weaver or knitter over a broad range. The ratio of Yarn B to Yam A
on the outside of the garment may range from 99/1 to 10/90. A
preferred range is 95/1 to 30/70. After the fabric is made
containing the two yams it can be finished in piece form with the
durable hydrophobic treatments such as application of
fluorochemicals, silicones, or waxes, etc. Appropriate crosslinking
agents can be included in the formula to ensure good durability to
the preferred cleaning procedure, which is typically home
laundering. Since Yarn B is predominantly on the outside of the
fabric and includes the resist treatment, the hydrophobic treatment
material will be preferentially deposited on the more absorbent and
receptive Yarn A, which does not contain the resist. The resist can
be designed in such a way to be readily removed by a scouring
process, for example, water with a detergent or a mild alkaline
solution. If the resist is formulated and/or applied in such a way
that the durable hydrophobic treatment material deposits on the yam
containing the resist, it cannot bond to the cotton fiber (which
contains the resist). Consequently, any of the durable hydrophobic
treatment (e.g. fluorocarbon or silicone) which deposits on Yarn A
containing the resist can be readily removed in a subsequent wash
or scour. The subsequent wash or scour can be done at the mill or
by the consumer in the home laundry.
[0065] The technique described here (i.e. using a resist)
eliminates potential difficulties with yarn application of durable
hydrophobic treatments, such as filtering by the yarn package or
breaking of the emulsion by the shear forces in the package
machine.
[0066] Another possibility for yarn treatments is to apply the
hydrophobic treatments directly to the yarn in a discontinuous
manner, such as by space dyeing or sprays. The same logic applies
here as in the fiber treatment or above yarn treatment examples.
Such yarn can be used to produce garments with reduced absorbent
capacity while maintaining the necessary degree of wicking for the
activity and environment.
[0067] Embodiment 3:
[0068] Embodiment 3 involves fabric treatments which are performed
in a discontinuous fashion rather than typical commercial
treatments which are done in a continuous fashion (meaning that
they result in a continuous application of the hydrophobic
treatment to the fabric).
[0069] In this embodiment, the treatment must result in a
discontinuous finish. The discontinuous nature of the finishing
treatment in the end product or garment is a key feature in the
above embodiments as well. If a highly hydrophobic finishing
treatment is applied in a continuous fashion on a hydrophilic
fabric such as cotton, the garment will not wick. If the garment
does not wick, moisture will not be transported away from the skin.
The garment will tend to stay dry even when the wearer is
perspiring heavily, but the liquid will predominantly run or drip
down the body because it can not readily pass into the garment (in
the Z direction meaning normal to the plane of the fabric). Also
the microclimate between the skin and the garment will quickly
approach 100% relative humidity and the result is a very
uncomfortable garment.
[0070] An example of the treated fabric is shown in FIG. 4. A
treated fabric (10) is placed against the skin of the wearer (20)
and perspiration is generated through the activity of the wearer.
The perspiration does not pass through the non-absorbent areas (30)
but does pass through the wicking windows (40) to the outer layer
of the fabric (50) where it can evaporate, resulting in evaporative
cooling.
[0071] On fabric, the discontinuous treatments may be done, for
example, by printing, dripping, foam or spraying. Resist treatments
may be used on the fabric in a similar discontinuous manner.
Suitable resist treatments include any treatment that can be
applied to the fabric that will block the hydrophobic treatments
from forming a permanent bond with the fibers, yarns or fabric.
Resist treatments can be removed by a subsequent washing, scouring
or rinsing operation and will allow any hydrophobic treatments
which were applied on top of the areas that were resist treated to
also be removed or washed away from those areas. There are a wide
variety of resist treatments that can be used, and anything that
prevents a subsequent hydrophobic treatment from bonding in that
area may be suitable. Examples of such resist treatments include
natural and synthetic gums and resins, emulsifiable oils or waxes
and a variety of natural or synthetic polymers. Resist treatments
require at least two steps. First, the resist treatment is applied,
with or without an intermediate drying step. Second, the
hydrophobic treatment can be applied directly to the fabric. The
application can be accomplished by any common application technique
that is normally used for applying dyes and finishes to fabrics.
These include, for example, padding, dipping, sprays, foams, weirs,
and the like, and may include the subsequent extraction of the
excess liquor by squeezing, vacuum, doctor blades, air knives,
centrifuges, etc.
[0072] Direct application of the hydrophobic treatment is another
option, but the treatments must be applied in a discontinuous
manner. In both the resist method described above and the direct
application method, the ratio of treated surface area to untreated
surface area on both the inside and outside of the fabric is an
important consideration. The size and design of the areas or
islands to be treated versus those to be left untreated are also
important. These many design options allow for substantial
versatility and creativity by the designer of this apparel. As in
embodiment 1 (above), garments can be made from 100% cotton and can
be tailored to the specific activity, environment and personal
preferences of the wearer.
[0073] Printing fabric with dyes or pigments is a common method of
coloration. There are several printing techniques that can be used,
including gravure, roller and screen printing. Any of the
commercially practiced printing techniques can be used in this
embodiment. The printing may be done with or without colorants. Any
of the durable hydrophobic treating agents as described above, such
as fluorochemicals, silicones, waxes or other materials, may be
used. If dying to a solid shade is to be done, it is preferably
done before printing with the above-mentioned treating agents.
[0074] Those skilled in the art of printing are familiar with
various thickeners which are used to keep the colorants in the
normal printing process from migrating and to maintain a clear or
well-defined print. In printing in general, there are a number of
variables which can be controlled. Some variables such as print
paste viscosity, amount of print paste applied, roller/wiper
pressure, speed, etc., can be used to control the depth of
penetration of the print paste.
[0075] One option is to print on the face of the fabric (the side
to be worn outside) and adjust the variables mentioned above (such
as print paste viscosity) to allow the print paste containing the
hydrophobic treatment (with or without colorant) to pass through to
the back of the fabric (the side to be worn on the inside of the
garment). A garment can be made where 50% of the fabric from which
the garment is made is printed with the print paste containing the
hydrophobic agent or chemical(s). Penetration of the print paste
may be complete from the face to the back of the fabric. The print
pattern may be simple or complex and the size of the pattern may
vary. The pattern may be, for example, stripes or dots but the size
is preferably relatively small to distribute the untreated fiber
which can serve as the wicking medium, uniformly throughout the
fabric and garment.
[0076] In one embodiment, the print pattern includes circles (dots)
ranging from 1 mm to 50 mm in diameter, with spacing between the
dots equal to the diameter of the dot. A preferred range for the
diameter of the dots and spacing between the dots (in both X and Y
directions) is 2 mm to 20 mm. A more preferred spacing is 2 mm to
10 mm. The spacing of the print pattern does not need to be uniform
and the pattern itself may vary over an almost infinite range.
[0077] A "wicking window" effect may also be achieved with this
technique. By "wicking window" we mean untreated areas in the
garment, due to a print pattern which allows liquid moisture (or
perspiration) to pass through from the inside of the garment to the
outside of the garment. Performance characteristics of the garment,
using the printing method of manufacture, may be further enhanced
by printing on the back of the fabric (the side to be worn next to
the skin) rather than the face. The print paste viscosity and other
printing variables can be controlled to limit the depth of
penetration of the print paste (containing the hydrophobic
treatment) into the fabric in the Z direction. These printing
variables can be adjusted such that the print paste and the
subsequent hydrophobic islands do not penetrate to the face of the
fabric. A garment can be produced using these techniques which is
predominantly hydrophobic on the inside and predominantly
hydrophilic on the outside. By having many small areas (i.e., a
small print pattern) on the inside of the garment which are
untreated and highly wicking, liquid moisture will be pulled away
from the body through these "wicking windows" and into the outside
of the garment, which is predominantly untreated and highly
wickable. In this example, the outside of the fabric from which the
garments are made may be completely untreated so that maximum
evaporation rate and evaporative cooling can be maintained, if
desired. The inside of the garment, which overall is more
hydrophobic, will have a much reduced absorbent capacity and a much
reduced tendency to stick to the (hydrophilic) skin of the wearer.
This embodiment allows for creativity in the design of such
garments. Garments made by this technique can be engineered to the
activity, environment and or the preferences of the wearer.
[0078] Optionally, designs, letters, words, symbols, characters or
other two dimensional shapes can be printed into the fabric (or
knit or woven into the fabric, by using combinations of treated and
untreated yarns). This can be accomplished, for example, by adding
a colorant to the print paste, which also includes the durable
hydrophobic treatment chemistry(ies). It is generally known that
wet fabric or garments have a different appearance in many cases
and for many colors, than dry fabric or garments. In this
embodiment, the print pattern may be microscopic in size or at
least so small that it is not plainly visible. Performance apparel
can be created using larger designs which are highly visible and
still maintain most if not all of the advantages listed above in
embodiment 1.
[0079] The printing technique described in this embodiment may be
performed on bleached goods or on dyed goods. For most shades, with
the exception of very dark shades, wet areas of a fabric or garment
have a darker appearance than dry areas. Consequently, if the print
pattern is printed onto the outside of the fabric (the side to be
worn outside) the hydrophobic treatment will keep the printed area
from becoming wet during exercise, or activities involving
perspiration, or when worn outdoors under conditions of
precipitation. Hence, the print pattern will be visible, but only
(or predominantly) when the garment becomes wet. This effect can
also be achieved when printing on the inside of the fabric, if the
printing variables such as print paste viscosity are adjusted to
allow the print paste to penetrate to the outside of the fabric.
Accordingly, designs, letters, words, symbols, characters or other
two dimensional shapes can be printed onto the fabric (or garment)
that will become visible when the garment becomes wet. This concept
can be used in conjunction with recreational performance apparel or
on other products including non apparel items that may be used in
the shower or bath by children or others, swimwear, umbrellas,
raincoats etc. In some cases, other than recreational performance
apparel, it may be desirable to have a two sided treatment, such as
for raincoats or umbrellas. The inside of the product may be fully
treated with a durable water repellant, such as the inside of a
raincoat or umbrella. The outside may be printed (or the design
created by knitting or weaving) in a pattern desired by the
consumer. Two layered fabrics or laminates of two or more layers
may also be used to create the desired effect. This can allow for a
design or logo to appear when the product becomes wet. This effect
may be most pronounced when there is no dye or pigment used in the
print paste containing the hydrophobic treatment.
[0080] Embodiment 4:
[0081] Embodiment 4 involves forming multilayer fabrics. The
fabrics in this embodiment may incorporate wovens, knits, or
nonwovens or combinations thereof. In the case of nonwovens, the
layers may be very thin so that such multi-layered fabrics are not
necessarily very heavy. Such fabrics may be used as single layers
or as one of the layers in a layered system of dress for a
particular activity, such as backpacking or snow skiing.
[0082] In one embodiment, two layers are used. One layer, Layer A,
is a hydrophilic fiber fabric (such as cotton) that has been
treated to render it hydrophobic with much reduced absorbent
capacity under normal conditions of use. A second layer, Layer B,
is an untreated hydrophilic fabric such as cotton. The hydrophilic
Layer B may be used as the outside layer to produce a performance
garment for activities involving perspiration. The two layers may
be attached using methods well known to those of skill in the art,
including laminating using heat and pressure with various bonding
agents such as (low melting) thermoplastic powders, fibers or
films. If films are used, they are preferably breathable. Other
types of chemical bonding can also be used and may be applied by
coating or any one sided application technique such as foam, spray,
doctor blade, etc. Strictly mechanical means of bonding the layers
can also be used, for example, needle punching, stitch-bonding, or
hydroentangling (also known as spunlace or water jet
entangling).
[0083] To produce wicking or capillary movement of liquid (i.e.,
perspiration) from the inside of the garment to the outside of the
garment where it can evaporate or move to the next layer away from
the skin, channels of liquid movement through the inner hydrophobic
Layer A must be created. Such channels ("wicking windows") can be
created, for example, by needle punching or by hydroentangling
techniques. In needle punching, those skilled in the art can select
appropriate equipment and equipment set up. The equipment may be
either rotary or flatbed. Variables such as needle type, size,
spacing and machine speeds can be controlled to vary the amount or
degree of needling and the penetration of Layer B through Layer A.
Large needles may be used to create relatively large wicking
channels in the fabric and produce a fabric with voids or small
holes where the needles have been withdrawn from the substrate.
Fibers from the hydrophilic Layer B can be pushed though the
hydrophobic Layer A to produce the channels or "wicking windows"
which are actually bundles of hydrophilic fibers which serve as
pathways of wicking.
[0084] The outer layer, Layer B, and the inner layer, Layer A, may
each range in weight, for example, from about 1 oz./square yard to
more than 20 oz./square yard. A more desirable range is about 1 to
about 14 ounces per square yard for recreational performance
apparel and about 0.1 to about 8.0 ounces per square yard for
absorbent products such as cover stock or wipes. The optimum area
density of each layer will depend on a number of factors, including
the nature of the end product, intended end use or activity,
environment, personal preferences and layering system (if any) used
by the wearer.
[0085] By varying the relative area densities, constructions, types
of fabrics (i.e. wovens, knits or nonwovens), methods of lamination
or making the two or more layers into one, and the amount and
nature of needling or hydroentangling, the design possibilities are
many. As in the other embodiments, garments can be engineered to
specific activities; environments; personal preferences and
layering systems (if any) of the wearer. Likewise, absorbent
products, which are typically nonwovens, can be engineered with a
broad range of properties.
[0086] Embodiment 5:
[0087] Embodiment 5 involves using crosslinking as a means of
reducing the absorbent capacity: Any of above embodiments or
methods of producing recreational performance apparel from 100%
cotton (or other cellulosic fibers) can be further enhanced or
modified by including crosslinking resins applied in a continuous
or discontinuous fashion. Crosslinking resins such as those used to
produce wrinkle resistant cotton products (e.g., citric acid,
maleic acid, DMDHEU, BTCA, other polycarboxylic acids such as
polymaleic, etc.) can be used. Such treatment chemistries can be
applied to fiber, yarn, fabric or garments. These materials will
effectively reduce the absorbent capacity of regular (untreated)
cotton by about 5 to 30% or more, depending on the chemistry used,
the application amount, and the technique used (including curing),
and the test method used for the absorbent capacity measurement.
They can reduce the water that is held inside the fiber itself by
bonding adjacent cellulose molecules and reducing the swelling of
the fiber when it is exposed to a moist environment. Such
crosslinking treatments do not necessarily eliminate wicking
however, and therefore can be applied uniformly to the entire
substrate as is common for wrinkle resist cotton apparel.
Discontinuous means of application can also be used. These
treatments provide the textiles with sufficient hydrophobicity to
reduce the absorbent capacity of the treated substrate. These
treatments may also provide the textiles with wrinkle resistance,
smooth drying properties and durability to repeated laundering in
alkaline detergents. The crosslinking treatments may include the
use of a suitable catalyst (such as, for example, curing catalysts
such as magnesium chloride, alkali metal hypophosphites, alkali
metal phosphites, alkali metal polyphosphates, alkali metal
dihydrogen phosphates, and many others) and/or the use of heat.
[0088] This technique can be used as a stand alone method (i.e.,
without the inclusion of other treatment chemistry such as
fluorochemicals, silicones or waxes) for producing the recreational
performance apparel. Alternatively, this technique may be used in
conjunction with a hydrophobic treatment.
[0089] In this embodiment, light weight, thinner fabrics are
preferred. Thinner fabrics have less absorbent capacity in general
and hence will not get as heavy when wet and will dry faster than
thicker fabrics. For example, area densities for recreational
performance apparel in the range of about 1 to 8 oz./square yard
are preferred, with area densities in the range of about 2 to 6
oz./square yard being more preferred. For cover stock (i.e.
topsheets) used in absorbent products such as disposable diapers,
much lighter fabrics are used, such as in the range of 18 grams per
square meter.
[0090] Resins, as noted in this embodiment, will reduce absorbent
capacity but allow wicking to be maintained. The resin may be
applied before, after or in conjunction with the hydrophobic
treatment. Resins and such hydrophobic treatments mentioned in
these embodiments are both normally applied after dyeing. However,
dying may be done subsequently for special or novelty effects.
[0091] Embodiment 6:
[0092] Embodiment 6 involves garment treatments: As in Embodiment
3, garments may be printed, sprayed, dipped or otherwise treated to
produce a discontinuous treatment. The discontinuous treatment
allows many small channels or "wicking window" in the fabric from
which the garment is made. Garment printing is a common technique.
Since the durable hydrophobic chemistry can be chosen to be
invisible, patterns do not need to be carefully aligned from front
to back in the garment.
[0093] In a preferred embodiment, the print paste does not
penetrate through the fabric. Garments may be turned inside out for
treatment, so that only the side of the garment in contact with
skin is treated. In this manner, one side of the garment is
inherently more hydrophobic than the other.
[0094] A resist treatment may be used as described above in other
embodiments (i.e., applied in a discontinuous manner by printing,
spray, foam, etc.) such that the durable hydrophobic treatment
chemistry can be applied to the whole garment by common garment
dyeing and finishing techniques. In this case, the resist will keep
the durable hydrophobic chemistry from attaching to the cotton
fiber.
[0095] Any of the above embodiments may be used to tailor apparel
for a variety of applications, activities, environments, or
personal preferences of the wearer. The area density of fabrics for
any of the above examples may vary, for example, from about 1 to
about 30 oz./square yard. For a single layer warm weather activity
the preferred range will be about 2 to 8 oz./square yard. For an
outerwear garment for cold weather applications, the preferred
weight range will be from about 4 to about 20 oz./square yard.
[0096] Any of the above methods can be used with blends of cotton
and/or any hydrophilic fiber and/or a synthetic or any hydrophobic
fiber such as polyester, polypropylene or nylon.
[0097] Any of the above garments may be used as a single layer or
as one layer of a multi-layer system of dress, for example, for
cold weather outdoor activities.
[0098] In each of the embodiments described above, preferably
between 40 and 90% of the cotton fabric next to the skin remains
dry. Preferably between 10 and 60% of the cotton fabric next to the
skin is untreated, absorbent and wicks moisture away from the skin
and into the outside of the fabric where it evaporates and cools,
in a similar manner to an untreated garment.
[0099] The hydrophobic treatments in each of the embodiments can be
attached to the cotton and/or other cellulosic fibers using any
known methodology. Preferably, the methodology involves forming a
covalent bond between the hydroxy groups on the cellulosic
substrate and reactive functional groups (for example, hydroxyl,
carboxylic, phosphoric, sulfonic or other acids, amines, halogens
and the like) on the compounds to be attached. The hydrophobic
treatment chemistry may itself contain crosslinking groups capable
of producing durability by crosslinking to itself or directly to
the cotton or other cellulosic or other hydrophilic fiber. Another
option is that a separate crosslinking agent is used to bond the
hydrophilic chemistry or any chemistry that can reduce the
absorbent capacity of the hydrophilic fiber such as cellulose, to
the cellulose.
Embodiments Related to Absorbent Products
[0100] Although the above embodiments specifically describe
applications involving garments, the techniques, fibers, yarns, and
fabrics described in the embodiments may also be used to make other
articles of manufacture. These articles include, but are not
limited to, absorbent products such as diapers and sanitary
napkins.
[0101] Generally, diapers and sanitary napkins include a topsheet
that is worn next to the user's skin and an absorbent core that is
used to store bodily fluids such as urine and menstrual fluid. The
topsheet has an inside surface for contacting the user's skin and
an outside surface. The absorbent core is adjacent the outside
surface of the topsheet. The absorbent core may be formed from any
absorbent material such as, for example, hydrophilic fibers (such
as cellulosic fibers), superabsorbent polymers, and mixtures
thereof. As used herein, the absorbent core includes any
acquisition layer between the final storage area (for bodily
fluids) of the absorbent product and the topsheet.
[0102] The topsheet is typically a nonwoven and may have a
predominantly hydrophobic inside (i.e., a topsheet that has a
reduced absorbent capacity) and an outside that is predominantly
absorbent. The topsheet may also be uniformly and predominantly
hydrophobic from inside to outside, as long as it is designed to
allow fluid to pass quickly through the topsheet and into the
absorbent core.
[0103] The topsheet of such diapers and sanitary napkins may be
composed, for example, of the following: (1) 100% cellulosic
fibers; (2) a blend of cellulosic fibers and synthetic fibers such
as polypropylene, polyester, or nylon; (3) a blend of cellulosic
fibers which have been treated with a hydrophobic treatment and a
synthetic fiber which has wicking properties; and (4) a blend of
absorbent cotton (or other hydrophilic fiber) and cotton (or other
hydrophilic fiber) which has been treated or processed to be
hydrophobic. Cotton linters, comber, gin motes, shoddy, and various
other lower cost cotton waste materials may be used as the source
of cotton. The fibers used in the topsheet may be treated with any
of the hydrophobic treatments described herein, such as, for
example, application of silicones, waxes, fluorocarbons, zirconium
compounds, oils, latexes, or crosslinking resins or agents includes
carboxylic acids and polycarboxylic acids such as citric, maleic,
butane tetra carboxylic, or polymaleic acids. Blends of these
hydrophobic treatment materials may also be used.
[0104] When cotton is used, the normal scouring and bleaching
process which is used to purify and make cotton absorbent may be
modified to allow the cotton to maintain the normal hydrophobic
properties of raw cotton. This is done by not removing all of the
natural cotton oils and waxes which are contained on the surface
(cuticle) of the natural raw cotton (i.e., all or a portion of the
natural oils and/or waxes on the fiber surface are maintained). For
example, a normal scouring and bleaching process for cotton in a
kier (i.e., a high pressure vessel) may comprise the following
steps:
[0105] (1) Scour for approximately 50-60 minutes at about
265.degree. F. and about 40 lb/in.sup.2. In this step, the cotton
fiber is placed into the kier and may be wetted out with warm water
and surfactant if needed. The temperature and pressure of the kier
is gradually brought to about 265.degree. F. and about 40
lb/in.sup.2 where it is held for approximately 50-60 minutes. The
following mixture is circulated through the cotton fiber during
this step:
[0106] 3.5-5.5% NaOH (100% NaOH basis)
[0107] 0.6-0.8% Surfactant/emulsifier
[0108] 0.1-0.4% chelate (alkali stable).
[0109] The liquor to goods ratio in the kier is about 4:1 to 5:1
and the percentages are the percentages on weight of goods (OWG).
At the end of the step, the cotton fiber is washed thoroughly with
water.
[0110] (2) Bleach for approximately 30 minutes at about 230.degree.
F. and about 20 lb/in.sup.2. In this step, the temperature and
pressure of the kier is gradually brought to about 230.degree. F.
and about 20 lb/in.sup.2 where it is held for approximately 30
minutes. The following mixture is circulated through the cotton
fiber during this step:
[0111] 0.6-1.2% organic stabilizer such as Dequest 2066 stabilizer
from Monsanto
[0112] 0.6-1.2% buffer such as sodium tripolyphosphate
[0113] 0-0.4% NaOH (100% NaOH basis)
[0114] 0-0.2% surfactant/wetting agent.
[0115] The liquor to goods ratio in the kier is about 4:1 to 5:1
and the percentages are the percentages on weight of goods (OWG).
At the end of the second step, the cotton fiber is washed
thoroughly with water and is acidified with 0.6-0.8% of 56% acetic
acid on the last rinse.
[0116] This normal scouring and bleaching process can be modified
to yield purified and bleached fiber without removing any or
without removing all of the natural waxes and/or oils such that the
cotton fiber maintains some or all of the hydrophobic properties of
raw cotton (i.e., the fiber has a reduced absorbent capacity
compared to normal scoured and bleached cotton fiber). According to
the present invention, the modification of the normal scouring and
bleaching process involves reducing the concentration of one or
both of the base or the oxidizing agent, replacing the base and/or
the oxidizing agents with other agents, reducing the time of one or
both of the scouring or bleaching steps, and/or reducing the
temperature in one or both of the scouring or bleaching steps. As
an example, in the scouring and bleaching process described above,
one or more of the following modifications could be used to leave
all or some of the natural waxes and/or oils on the resulting
bleached and purified cotton fibers: (1) the temperature of the
scouring step could be reduced from 265.degree. F. to 80.degree.
C.; (2) the NaOH used in the scouring step could be reduced to
about 0.5% or less on weight of goods; (3) the NaOH could be
replaced in the scouring and/or bleaching steps with sodium
carbonate. An alternative means to maintain all or a portion of the
natural oils and/or waxes on the cotton is by depositing on the
fiber during the preparation process hard water salts or compounds
or complexes containing hard water metals (e.g. calcium and
magnesium) either alone or in combination with a variety of other
materials including silicates or any of the hydrophobic treatment
materials mentioned above. These modifications along with the times
of treatment during each step may be adjusted as needed to achieve
the desired level of purification and whitening as well as the
desired level of absorbency/hydrophobicity. The resulting fibers
may be used alone in a cellulosic substrate such as the topsheet of
an absorbent product, may be blended with normal hydrophilic cotton
(i.e., cotton that has been subjected to the normal scouring and
bleaching process), or may be blended with synthetic fibers such as
polypropylene that have hydrophilic or wicking properties.
[0117] When the top sheet is 100% cotton or other hydrophilic
cellulosic fiber, the inside of the top sheet may be treated in a
discontinuous manner with a hydrophobic treatment after the
nonwoven web has been formed. The discontinuous hydrophobic
treatment may be applied to the topsheet by printing, spraying,
foaming, air lay powder or liquid deposition, dosing, coating,
dripping, blowing, vacuum, water jets, plasma or hydroentangling
devices. Because topsheets are often very thin and light weight
(e.g. 18 grams per square meter), there will be rapid and complete
penetration of the treatment to the opposite side of the web in
some embodiments no matter which side of the topsheet is treated
.
[0118] The top sheet may also be produced such that the entire top
sheet is composed of 100% cotton (or other hydrophilic fiber or
blends of cotton and synthetic fibers) which has been treated or
processed such that all of the topsheet is hydrophobic or has a
substantially reduced absorbent capacity. In such an embodiment,
the top sheet may be an apertured nonwoven where the apertures
function as "wicking windows" or channels for the flow of body
fluids (e.g. urine, menstrual fluid, etc.) into the absorbent core
of the end product. The size of the apertures preferably ranges
from about 0.01 to about 10.0 millimeters. The spacing between the
apertures preferably ranges from about 0.01 millimeters to about
10.0 millimeters and may be uniform or non-uniform. The apertures
may be created by hydroentangling, air jets, water jets, or needle
punching. The apertures may contain hydrophilic or wicking fibers
from a second layer of the topsheet, from an adjacent nonwoven
substrate, from an acquisition layer, or from the absorbent core.
In such an embodiment, the hydrophilic fibers from the second
layer, adjacent nonwoven substrate, acquisition layer, or absorbent
core may be inserted or forced into the apertures of the topsheet
by pressure, vacuum, laminating, air jets, or water jets. The
hydrophilic wicking fibers from a second layer, an adjacent
nonwoven substrate, an acquisition layer, or an absorbent core can
serve to start the flow through the apertures and serve as wicking
windows or channels of flow simply by the pressure exerted by the
head of body fluid or the combination of the head of body fluid and
skin contact.
[0119] In another embodiment, a hydrophilic synthetic fiber with
wicking properties is blended with a hydrophobic cellulosic fiber
(such as cotton) and made into a nonwoven web by carding, air lay,
wet lay, Rando Webber, hydroentangling, thermal bonding, chemical
bonding, needlepunching or any combination thereof. The hydrophilic
synthetic fiber and the hydrophobic cellulosic fiber are
predominantly on opposite sides of the nonwoven web, thus allowing
one side to be predominantly hydrophobic (but still wick or readily
pass body fluids) and the other side to be predominantly
hydrophilic (to pull body fluids through the predominantly
hydrophobic side of the web). The physical properties of the
hydrophilic synthetic fiber and the hydrophobic cellulosic fiber
may be significantly different to promote the migration of the two
fibers to the opposite sides of the nonwoven web in the web
manufacturing process. For example, the denier and/or staple length
of the synthetic fiber and/or the micronaire and/or staple length
of the cellulosic fiber may be used to promote the migration of the
two fibers to opposite sides of the web in the web forming process.
The hydrophilic synthetic fiber in this embodiment may also be
replaced with hydrophilic cellulosic fiber, and both the
hydrophobic fibers and the hydrophilic fibers may be cotton.
[0120] In yet another embodiment, the nonwoven topsheet is composed
of two layers. One layer may be hydrophilic cellulosic or synthetic
fiber (that will wick) and the second layer may be a hydrophobic
cellulosic or synthetic fiber. The hydrophobic layer is to be worn
next to the skin. The two layers may be formed and/or combined by
any of the following means or combinations thereof: (1) bonding two
nonwoven webs by chemical bonding, laminating, hydroentangling, air
jets, thermal bonding using fibers, powder bonding, calendaring,
needlepunching, air lay, wet lay, pressure or vacuum, or
combinations thereof, (2) forming a first nonwoven web (by any
conventional means) and subsequently or simultaneously depositing a
second layer of fibers by air lay; wet lay; carding; blowing,
vacuum, or combinations thereof; or (3) tandem carding, carding
combined spun bonding, melt blowing, hydroentangling, or
needlepunching. Wicking may be achieved through the hydrophobic
layer during product use by any of the following means or
combinations thereof: hydroentangling; air jets, water jet,
pressure, vacuum; needle punching, or simply by using webs or
layers in the web which are very thin (e.g., from 0.0001
millimeters to 2.0 millimeters) such that voids between fibers or
holes exist in one or both of the layers to allow liquid to wick
from the hydrophobic side to the hydrophilic side of the nonwoven
web or webs.
[0121] The topsheet may be a blend of hydrophobic (or reduced
absorbent capacity) fiber and hydrophilic fibers, with the ratio of
the two fibers ranging from 1/99 to 99/1 depending on the
absorbency and flow characteristics required for the end
product.
[0122] Optional Components
[0123] Additional components can optionally be added to the fiber,
yarn, fabric and/or garment compositions described herein. These
include, but are not limited to, fire retardants, dyes, wrinkle
resist agents, foaming agents, buffers, pH stabilizers, fixing
agents, stain repellants such as fluorocarbons, soil repellants,
wetting agents, softeners, water repellants, stain release agents,
optical brighteners, emulsifiers, and surfactants.
[0124] Methods of Evaluating the Compositions
[0125] The suitability of the treatment compositions for an
intended use will depend on the ability of the treated cellulosic
substrate to pass various standard performance tests. Some examples
of suitable performance tests are present in the Examples below,
while others are known to those skilled in the art of manufacture
of the type of end products noted above. Using these tests, with a
suitably prepared composition, one can readily determine the
efficacy of the composition for its intended use.
EXAMPLES
[0126] The compositions and methods described herein will be better
understood with reference to the following non-limiting
examples.
Example 1
Gross Absorbency (Absorbent Capacity) Study of Water on Fabric:
Comparing Fluorocarbon Printed Fabric vs. Untreated 100% Cotton
Control Fabric
SUMMARY
[0127] Printing a fluorocarbon (FC)/resin formulation on a washed
and prepared 100% cotton knit fabric significantly reduced the
absorbent capacity (or total wet pick up) of the test fabric
compared to an untreated control fabric.
[0128] The idea of printing a fluorocarbon (FC) with approximately
50% penetration on the back of 100% cotton knit fabric to reduce
the overall water uptake (and therefore reduce the drying time and
improve various other properties such as tendency to sag when wet
or stick to the skin, etc.) was evaluated.
Introduction
[0129] Altering the properties of naturally high absorbing 100%
cotton fabric to achieve lower water absorbency without sacrificing
comfort and feel was the goal of this example. As determined in
various publications: the drying time of a garment depends on the
amount of water absorbed, not the fiber type.
[0130] Our previous work indicated that there was not a negative
influence in respect to air breathability (Frazier) and moisture
vapor transport (Mocon) when using FC on cotton fabric. Frazier and
Mocon are two important factors closely related to the sensation of
comfort.
Objective
[0131] The objective of this example was to develop a method for
quantitative measurements of gross/total water absorbency on
fluorocarbon (FC) printed fabric compared to an untreated control
fabric. This method can be used to demonstrate that a targeted FC
application effectively reduces the overall water uptake on 100%
cotton fabric, subsequently reducing the drying time, but
maintaining wicking characteristics.
Experimental
[0132] The fabric used for this study was 18 cut jersey, 16
singles, ring spun 100% cotton knit fabric SK-1499-2C. The fabric
was received as greige fabric and prepared in the Dyeing and
Finishing Research Lab (DFRL). The fabric was bleached and then
acid neutralized in a Sclavos machine. The following steps were
taken to prepare the fabric for printing.
[0133] Additional Scouring Step:
[0134] A large swatch (approximately 2-3 yards) was cut from the
bleached fabric roll then scoured and extracted in warm water in a
regular washing machine. No detergent was added, but 80g/80L
"Carbapon CDN" from "Clariant", which is a slightly acidic chemical
formulation, was used to ensure complete removal of any residual
detergents left behind from previous washing steps. The fabric was
dried in a dryer for 60 minutes or until completely dry. Universal
indicator was dropped on the dry fabric to check the pH. The
resulting orange color indicated a pH of around 5.
[0135] Preparation for Printing:
[0136] Four sample swatches were cut out, using a template
measuring 17 inches.times.24 inches. This was the most suitable
fabric size and large enough to be covered by the striped area of
the print screen.
[0137] The synthetic print paste used for the experiment was
"Imperon LV-5" in an 8% concentration in water. (Synthetic paste
was preferred over the commonly used starch- ether paste since it
required no after wash due to yellowing at the higher curing
temperatures necessary for the fixation of the FC/resin system).
The consistency of the paste was intentionally prepared to be of
higher than normal viscosity. This enabled more FC formulation to
be added to the paste (hence increasing the active fluorine level)
without attenuation.
[0138] A formulation of Mitsubishi's FC "Repearl FC-35" in a 6%
concentration and the resin "Repearl MF" in a 3% concentration on
weight of bath (OWB) were mixed with the paste in a ratio of 1:1.5
(paste to formulation). To enhance the visibility of the paste,
some blue dye (Tectilon Blue 4 RS KWL 200 and 5g/200 ml water) was
added.
[0139] Printing Setting
[0140] The individual sample swatches were labeled and the dry
weight recorded. Each swatch was placed with the backside facing
the screen on the printing table. After installing the stripe
patterned print screen on top of the fabric, the metal rod and
table settings were selected.
[0141] Settings: rod size=15 mm (largest), speed=20, polarity M=2
(1 is for small bars, 2 for large ones), passes=2, and
magnet=6.
[0142] Printing was performed as follows:
[0143] After the screen and the metal rod were in place, the power
switch was turned to position "1 " (on). An approximately 1/2 to 1
inch thick layer of the now blue print paste was poured in front of
the rod and the .rarw.M.fwdarw.switch turned to "2" which moved the
bar to the right side of the screen. Upon completion the power was
turned off, the rod lifted and placed so that the paste was in
front of it to the left. The paste was replenished when necessary,
the power turned back on and the .rarw.M.fwdarw.switch turned to
the "1" position, moving the bar to the left. The last step
concluded the printing procedure and the screen was lifted to
remove the now blue striped printed fabric. The wet weight was
recorded and the fabric was put on a hanger. The other swatches
were finished the same way and put in a Sussman garment oven to dry
at 230.degree. F. (110.degree. C.) for 20 minutes. They were then
immediately cured at 338.degree. F. (170.degree. C.) for 3 )
minutes.
[0144] Gross Absorbency Measurements:
[0145] The gross absorbency trials were performed on fabric 20/1,
which had a wet pickup (WPU) of 56.85% (print paste with FC). The
fabric was cut in half. A test series was conducted on half of the
fabric right after printing. The other half was subjected to one
home laundering (HL) using warm water and liquid Tide and then
dried in a garment oven. A small fabric piece of the unlaundered
and home laundered (HL) swatches were sent to a testing lab for
fluorine analyses.
[0146] Each fabric half was tested in seven replicate tests. The
sponge size was 4.5 inches.times.8.0 inches.times.3.0 inches, with
a surface area of 8.0 inches.times.4.5 inches. To be able to place
two swatches (one control, one printed) on the sponge surface, each
sample was cut out to be 4.0 inches.times.3.0 inches, which was
equal to 24 blue stripes per sample.
[0147] Test set up:
[0148] An aluminum dish measuring 12.5 inches (L).times.10.5 inches
(W).times.4.5 inches (H) was filled with cold tap water.
[0149] One of the two fine pore sponges, brand "Armaly, Big Blue
Wash Sponge," was thoroughly wetted under running tap water. It was
then placed in the middle of the aluminum dish and enough water
added to have the sponge completely saturated and the water level
up to approximately 1/4 of an inch below the sponge surface. The
other dry sponge was completely wrapped in aluminum foil, leaving a
non-absorbing but smooth and even surface at the bottom. The weight
of that sponge was 59.82 grams.
[0150] A piece of "Armaly, chamois drying cloth" covering exactly
the surface area of the sponge (8.0 inches.times.4.5 inches) was
pre-saturated with water as well and placed on top of the sponge in
the dish. The purpose of the cloth was to present a uniformly wet
surface area, ensuring even water absorbency of the samples.
[0151] Prior to testing all 4.times.3 inch swatches (printed and
controls) were labeled and weighed. The FC printed swatch was then
placed with the blue striped side (back of fabric) on the wet
sponge. The untreated control was added next to it (backside on
sponge) and they were both covered with the dry aluminum foil
wrapped sponge, functioning as a weight to keep the fabric from
curling.
[0152] The time until complete saturation of the printed fabric was
noted. The wet samples were then, one at a time, transferred into a
small pre-weight plastic dish and weighed on a top loading balance
to determine the wet pick up. All sample swatches, including the
home laundered ones, were processed this way.
[0153] Note: The water level in the dish had to be monitored and
adjusted due to the diminishing water readily absorbed by the
fabrics. The sponge, as well as the cloth, was rinsed after several
series to remove possible contamination of excess print paste, etc.
(especially for the unwashed samples).
Results and Discussion
[0154] TABLES I and II give a detailed overview of the water wet
pick up values observed on the unlaundered printed fabrics
including the control fabrics.
1TABLE I % WPU Values of FC Printed Fabrics (no HL) Dry Wet Fabric
Fabric % less H.sub.2O Sample Weight Weight % Time Until Absorbed
vs. ID in Grams in Grams WPU.sup.1 Saturation Control.sup.2 #1 1.57
5.38 242.7 20 minutes 55.3% #2 1.57 5.33 239.5 30 minutes 66.8% #3
1.62 5.45 236.4 60 minutes 63.7% #4 1.59 5.76 262.3 20 minutes
54.4% #5 1.58 5.54 250.6 16 minutes 60.4% #6 1.59 5.63 254.1 15
minutes 64.3% #7 1.58 5.58 253.2 30 minutes 58.2% Note: .sup.1% WPU
= (wet weight .times. 100.backslash.dry weight) - 100 .sup.2[% WPU
(control) .times. 100.backslash.% WPU (FC printed)] - 100
[0155] The saturation times were determined by periodically
checking on the samples until they were wet out completely.
2TABLE II % WPU Values of Untreated Controls (no HL) Wet Fabric
Weight Sample ID Dry Fabric Weight in Grams in Grams % WPU #1 1.60
7.63 376.9 #2 1.62 8.09 399.4 #3 1.60 7.79 386.9 #4 1.60 8.08 405.0
#5 1.63 8.18 401.9 #6 1.61 8.33 417.4 #7 1.62 8.11 400.6
[0156] The control fabric was always subjected to the same
conditions as the FC printed samples. For example, the control test
swatch was dried and cured at the same temperature as the printed
fabric. Further, it was left on the wet sponge until the printed
swatch was completely saturated. FIG. 1 shows a graphical display
of the WPU values of FC printed vs. untreated control fabric before
one home laundering (HL). TABLES III & IV give the absorbency
results of the fabrics tested after 1 HL with Tide.
3TABLE III % WPU of FC Printed Fabric after 1 HL Dry Wet Fabric
Fabric % Less H.sub.2O Sample Weight in Weight in Time Until
Absorbed vs. ID Grams Grams % WPU Saturation Control #1 1.52 5.38
253.9 10 minutes 52.9 #2 1.52 5.47 259.9 10 minutes 45.8 #3 1.56
5.52 253.8 10 minutes 47.4 #4 1.55 5.57 259.4 10 minutes 46.4 #5
1.53 5.47 257.5 12 minutes 52.4 #6 1.54 5.31 244.8 6 minutes 61.1
#7 1.55 5.33 243.9 10 minutes 59.4
[0157]
4TABLE IV % WPU of Control Fabrics after 1 HL Wet Fabric Weight
Sample ID Dry Fabric Weight in Grams in Grams % WPU #1 1.59 7.76
388.1 #2 1.61 7.71 378.9 #3 1.63 7.73 374.2 #4 1.62 7.77 379.6 #5
1.61 7.93 392.5 #6 1.61 7.96 394.4 #7 1.59 7.77 388.7
[0158] FIG. 2 shows a graphical display of the gross absorbency
after 1 HL.
[0159] FIG. 3 shows the % less water absorbed related to the
corresponding controls of the printed fabrics before and after 1
HL.
[0160] Fluorine test results of the printed fabrics (unwashed and
washed) are given in TABLE V. The samples were analyzed in
duplicate using the same sample size and number of stripes.
5TABLE V Fluorine Test Results Before & After 1 HL Sample ID %
Fluorine 20/1 unwashed 0.23 20/1 washed 0.23
Summarized Results
[0161] The FC proved to be durable and fixed since the fluorine
values before and after 1 HL remained the same. (A concentration of
at least 0.23% active fluorine is recommended). See TABLE V.
[0162] The gross absorbencies of the untreated controls were
insignificantly lower after 1 HL compared to the first series,
probably due to minimal shrinkage of the fabric after washing and
drying. See TABLES II & IV.
[0163] The water repellency of the printed fabrics was to be
observed by the dry, blue striped area on the back of the fabric.
The face of the fabric was wet and absorbent.
[0164] The FC printed samples had distinct lower water WPU values
before & after HL compared to the untreated controls. The
prolonged and irregular saturation times of the unwashed printed
fabrics were most likely caused by migrated print paste, which
should be readily overcome by improving the paste formulation. This
seems to be the most logical explanation since the samples absorbed
readily after 1 HL. See TABLES I to IV.
Conclusions
[0165] To validate the FC durability it is necessary to conduct a
brief home laundering study. Testing the printed fabric after 10
and up to 50 HL for fluorine should give an indication of the
fixation and the general influence of repeated detergent exposure
to the FC performance.
Example 2
Moisture Regain of FC Treated vs. Untreated 100% cotton Fabric
Summary
[0166] A fluorocarbon (FC) application does not affect the moisture
regain of 100% cotton fabric. The amount of moisture a fabric
absorbs is related to its environment: the higher the humidity, the
higher the moisture regain.
Introduction
[0167] This experiment was designed to develop a fabric
construction/chemical treatment that reduces the water absorbency
of 100% cotton fabric. The objective was to determine the influence
of a FC treatment on the natural moisture regain of 100% cotton
fabric.
Experimental
[0168] Fabrics from previous trials were used for this brief study.
A 100% cotton blue T-shirt from Hanes.RTM. as well as a swatch of a
white "beefy " T-shirt from Hanes.RTM. were used as untreated
control fabrics. FC treated samples were pieces of an olive 100%
cotton shirt from K-Mart.RTM. sprayed with Mitsubishi's 6%
"Repearl.RTM.F 35" and 3% "Repearl.RTM.MF" on the back of the shirt
at 100% WPU ("B in 100"). The second FC treated sample was a
"beefy" T-shirt printed with the same FC as mentioned above in 3%
Repearl.RTM.F 35/ 1.5% Repearl.RTM.MF concentration in stripe
pattern (covering approximately 50% of the fabric surface).
[0169] Experimental set up:
[0170] Each fabric was measured in duplicate. Sample swatches were
cut out with a weight between 8-10 grams, put into labeled glass
weighing bottles and dried in a forced air oven at 105.degree. C.
for 24 hours. The weighing bottles were cooled in a desiccator for
1/2 hour and the individual sample weights recorded on an
analytical balance. The actual moisture regain process was
conducted at the fiber processing center (FPC) in a conditioned
environment: the fabrics were removed from the bottles and placed
on a table for 4 hours to regain the previously expelled moisture.
Meanwhile, the weighing bottles were dried and cooled and while in
the desiccator, transported to the location of the fabrics. The
fabric samples were picked up and quickly added to the according
bottles, sealed with a glass cap and put back in the desiccator for
weighing. The difference in weight was noted which translated to
the amount of moisture picked up by the fabrics.
[0171] Note: This test was repeated twice on different days and the
room humidity and temperature recorded.
[0172] The following TABLES VI & VII give an overview of the
test results:
6TABLE VI Moisture Regain after 4 hours at 74.3.degree. F./47.2%
relative humidity Sample ID % Moisture Regain blue Hanes ctrl.
(untreated) 6.44 white "beefy" shirt ctrl. (untreated) 6.07 olive
shirt "B in 100" (FC sprayed) 5.99 FC printed cotton ctrl. fabric
6.16
[0173]
7TABLE VII Moisture Regain after 4 hours at 75.4.degree. F./56.2%
relative humidity Sample ID % Moisture Regain blues Hanes ctrl.
(untreated) 7.20 white "beefy" shirt ctrl. (untreated) 6.88 olive
shirt "B in 100" (FC sprayed) 6.87 FC printed cotton ctrl. fabric
6.92
Results and Discussion
[0174] FC treatment does not negatively influence the moisture
regain of a fabric as can be seen in TABLES VI & VII. The
percent of moisture a fabric absorbs is related to its environment,
here the relative humidity. The higher the relative humidity, the
higher the moisture regain of a fabric. (see FIGS. 1 & 2)
Example 3
Fluorocarbon Comfort Study For a Preliminary Wear Trial on 100%
Cotton T-shirts
Summary
[0175] Four solid colored 100% cotton T-shirts were purchased at
K-Mart.RTM.. The goal of this example was to use fluorocarbon
treatments to make cotton hydrophobic and therefore reduce or
partially eliminate the natural high water retention of cotton.
[0176] All four T-shirts were home laundered (HL) with AATCC
detergent once to remove any impurities and topical softeners and
dried in a regular dryer. Mitsubishi's fluorocarbon (FC)
"Repearl.RTM.F-35" in conjunction with their formaldehyde free
resin "Repearl.RTM.MF" were used for this evaluation.
[0177] Spray applications of the FC/resin formulation were targeted
for a 20% wet pickup (WP) on the inside of T-shirt #1, 20% WP on
the outside of shirt #2, 100% WP on the inside of shirt #3 and 100%
WP on the outside of shirt #4. They were dried/ cured and given to
a volunteer for wear trial for strenuous exercise.
[0178] All four T-shirts resulted in the same performance of
feeling extremely hot and uncomfortable due to the non-absorbing
cotton. One positive effect noticed were the soft hand and an
apparent "antimicrobial effect " (subdued odor) of this
formulation.
[0179] The shirt with the 100% WP outside was additionally
submitted to an enzyme/ stone wash to simulate chemical/ physical
abrasion in an attempt to partially remove the FC. Subsequent
absorbency and wicking tests proved this was not an effective means
of achieving some increase in hydrophilic properties of the fully
treated garment.
[0180] Furthermore, Frazier breathability tests indicated no
negative influence of the FC application compared to an untreated
T-shirt. Within the same brand (here, Hanes.RTM.) it even increased
the air permeability. This phenomenon led to the conclusion that
the "evaporative cooling" effect is probably the primary reason for
a feel of comfort during exercise.
[0181] Mocon moisture vapor transmission tests resulted in higher
values for two of the sprayed T-shirts compared to an untreated
"Hanes" control.
Introduction
[0182] Polypropylene, nylon and polyester are the domineering
synthetic fibers for the athletic wear market. Various fabric and
fiber constructions and the application of wicking agents to
enhance faster moisture transport away from the body make them
appealing for active wear. Garments made from those fibers are
lightweight and extremely fast drying, due to the synthetic
properties of the fibers of not absorbing moisture.
[0183] 100% cotton fabrics, on the other hand, supply a very nice
"feel" to the skin, but absorb all moisture/sweat present (due to
the porosity and molecular structure of cellulose) and therefore
become saturated and very heavy. That results in prolonged drying
times, discomfort and a "clammy" feeling.
Objective
[0184] The goal of this example was to reduce the natural
absorbency of cotton by either complete or partial FC treatment of
a fabric for example, to "seal" the cotton fibers to make them
hydrophobic.
[0185] Since fluorocarbons are primarily used for raingear and to
make fabrics water repellent, a combination of FC/ resin that would
act as a crosslinker to ensure permanent bonding to the cellulose
molecule was tested in the following described spray
application.
Experimental
[0186] Four solid colored 100% cotton T-shirts purchased at a
K-Mart (brands were: three Hanes.RTM. and one Route 66.RTM.. all in
size large) were thoroughly washed in a washing machine using AATCC
standard laundry detergent to remove any softeners and dried in a
dryer. Each shirt was labeled and the weight recorded before and
after treatment to determine the actual wet pickup (WP). The
treatment was performed as a spray application, using a formulation
of 6% Repearl F-35 (on weight of bath OWB) which is a fluorocarbon
manufactured by Mitsubishi and 3% (OWB) of their formaldehyde free
crosslinker Repearl MF.
[0187] The T-shirts were labeled as follows:
[0188] #1 "A out 100"
[0189] #2 "B in 100"
[0190] #3 "C out 20"
[0191] #4 "D in 20"
[0192] "In/out" stands for inside/outside treatment of the shirt;
the number indicates the target WP.
[0193] The actual wet pickup (WP) values are given in Table
VIII.
8TABLE VIII Wet pick up values Sample ID Target WP Actual WP A out
100 100% 101.37 B in 100 100% 99.02 C out 20 20% 28.61% D in 20 20%
32.24%
[0194] The shirts were dried on hangers at 220.degree. F. for about
15 min. or until dry and cured in a Sussman garment oven at
338.degree. F. for 2 min. An absorbency test resulted in no water
absorbency even after 10 min.
[0195] All four T-shirts were given to a volunteer for a one time
wear trial during regular gym workouts. Three of the treated plus
one untreated T-shirt as a control were also submitted for Mocon
testing. Results are given in Table IX.
9TABLE IX Mocon Test Data Sample ID Untreated Average FC treated
Average untreated control; dark blue 1748 1756.5 / / "Hanes"
T-shirt 1765 "B in 100" Not tested / 1612 1624.5 olive Hanes
T-shirt 1 HL 1637 "D in 20" Not tested / 2033 2001.5 Route 66 shirt
1970 "A out 100" Not tested / 2067 2044 Hanes shirt 2021
[0196] Frazier air permeability tests on four T-shirts were
conducted. The following Table X gives an overview of the obtained
data.
10TABLE X Frazier Air Breathability Values Sample ID Air
permeability value Hanes dark. blue control 83.95 Hanes olive "B in
100" 93.73 Hanes "A out 100" 96.18 Route 66 "D in 20" 76.16
[0197] After completion of the wear trial, shirt "A" (100% outside)
was submitted to an enzyme/stone wash to simulate chemical/physical
abrasion.
Enzyme Treatment
[0198] The chemical "abrasion procedure" involved an enzyme
treatment using the Unimac rotary dyeing machine in the finishing
lab. The liquor ratio was 10:1 and buffer A solution (3g/l) and
T-shirt were added at room temperature. The water temperature was
then subsequently raised to 135.degree. F. and the pH monitored to
be between 4.5 to 5.0.
[0199] Colase CRC (2g/l) was used as an enzyme and run for 30 min.,
then dropped and the shirt rinsed with hot water at 160.degree. F.
for 10 min.
[0200] The subsequent stone wash was performed as follows:
[0201] Stone Wash:
[0202] The wet shirt was moved from the Unimac to a 50 lb. garment
washing machine to perform the stone wash. The machine was loaded
with 5 lb. fabric plus an equal amount of stones and run with water
at room temperature for 45 min. All stones were removed before the
extraction and an additional rinse cycle at 120.degree. F. A
regular dryer was used to dry the shirt.
[0203] Absorbency/Wicking Tests:
[0204] A quick water absorbency test was conducted in several areas
on all 4 shirts to check the water repellency and the uniformity of
the FC. Since all 4 fabrics were extremely hydrophobic on both
sides (face and back) it was unnecessary to test the
wickability.
Results and Discussion
[0205] All FC spray applications penetrated the fabrics completely
and exhibited more "raincoat" like properties on the shirts than
anything else, but had a very soft hand. It was noted that all felt
extremely uncomfortable during exercise due to the fact that all
the moisture, sweat and heat retained close to the body.
[0206] Since all or most of both sides of the shirts were very
water repellent, neither one would show any dark sweat spots from
moisture being absorbed. One of the main reasons for experiencing a
"clammy" feeling can probably be attributed to the lack of
"evaporate cooling," prohibited by the non-absorbing FC.
[0207] Frazier breathability tests were conducted, performed on the
worn and on one, one-time washed shirt, showed no negative
influence of the FC on the "air flow" of the test samples. The
treated shirts of the same brand (Hanes) had even higher air
permeability values than the untreated control. Neither chemical
nor physical abrasion resulted in any surface damage of the treated
fabric to re-establish absorbency.
[0208] Mocon moisture vapor transmission tests revealed slightly
higher numbers for two of the FC treated T-shirts compared to the
untreated control.
Example 4
Drying Rate Study of Cotton vs. Synthetic Fabrics (Unimac Washing
Machine)
Summary
[0209] 100% cotton fabrics printed with a fluorocarbon (FC) have
the same or faster drying rate compared to 100% polyester synthetic
fabric. Test results within the four different Nike.RTM. fabrics
representing synthetics used for athletic wear gave variations in
initial percent WPU after Unimac extractions for two of the
samples, possibly due to the construction of the fabric.
Objective
[0210] The goal of this brief study was to obtain some data that
would support or refute the claim of synthetics drying faster
because of their inability to absorb any water at all. One issue
was whether FC-treated cotton fabric has a similar drying time to
100% synthetics.
Experimental
[0211] The study was laid out as follows:
[0212] Preparation of 100% Cotton Fabric
[0213] 100% cotton "beefy" T-shirts from Hanes.RTM. were home
laundered with liquid Tide.RTM. prior to treatment, dried and front
and the back was cut out. The individual swatches were labeled in
sets of two for each duplicate to be printed with a FC print paste
a) on the face and b) on the back of one fabric. The print
formulation consisted of a 1:1 ratio of the synthetic print paste
mixed with a FC solution of 2% FC (Mitsubishi 's "Repearl.RTM.FC
35") with 1% resin (Mitsubishi's "Repearl.RTM.MF") on weight of the
bath (OWB).
[0214] The print settings were:
11 rod size: 8 mm speed: 40 M: 1 1 pass/side Magnet: 3
[0215] All fabrics were weighed before and immediately after
printing to obtain Wet Pick Up (WPU) values (see TABLE XI for
details). After recording the WPU, the printed samples were put on
hangers, dried at 220.degree. F. for 20 minutes in a Sussman
garment oven and cured for 2 minutes at 338.degree. F.
12TABLE XI WPU values of FC printed samples Sample ID % WPU 4/1
Front 28.07 4/1 Back 26.66 4/2 Front 27.67 4/2 Back 25.97 4/3 Front
27.12 4/3 Back 27.32 4/4 Front 27.75 4/4 Back 26.15 4/5 Front 25.00
4/5 Back 18.93
[0216] Preparation of the Synthetic Fabrics
[0217] The synthetic fabrics selected for the trial were all
supplied by Nike.RTM. and are listed in TABLE XII.
13TABLE XII Synthetics Sample ID Sample ID Fiber ID # IM 19537
white 100% polyester # IM 32994 red 100% polyester Olive fabric
100% polyester Yellow fabric 100% polyester
[0218] General Testing of Samples
[0219] The FC printed 100% cotton fabrics as well as the 100%
polyester fabrics were all cut out to have the same weight of 27
grams per sample swatch. Each fabric was labeled, weighed on a top
loading balance and tested in duplicate. The "wetting out" process
was performed in the Unimac washing machine by adding one swatch of
each duplicate set of six test fabrics (4 synthetics, 1 FC printed
cotton, 1 untreated cotton ctrl.) to the machine, washing them for
5 minutes at 90.degree. F. (just water) and extraction at full spin
cycle speed for 2 minutes. The individual wet samples were then
weighed again to determine the amount of water picked up and
transferred on hangers to the fiber processing center (FPC for a
conditioned environment) to record the weight loss in 15 minute
increments over a 2 hour time period. The Unimac process was
repeated on the other duplicate set of fabrics as well.
[0220] The following tables and graphs display the test data.
14TABLE XIII % Remaining Water on Sample # IM 19537 (duplicate
testing) Time intervals in minutes % water on fabric 0 A) 68.55 B)
78.15 15 50.43 62.21 30 40.4 50.4 45 30.83 44.89 60 16.96 34.06 75
7.17 4.86 90 1.20 6.05 105 0.69 6.67 120 0.58 0.54
[0221]
15TABLE XIV % Remaining Water on Sample Yellow Nike (duplicate
testing) time intervals in minutes % water on fabric 0 48.62 52.64
15 34.09 39.75 30 24.78 31.53 45 18.22 24.69 60 7.86 14.73 75 1.01
7.05 90 B) 1.35 105 B) 0.65 120 DRY
[0222]
16TABLE XV % Remaining Water on olive Nike fabric (duplicate
testing) time intervals in minutes % water on fabric 0 116.16
140.04 15 92.72 109.82 30 77.93 92.39 45 65.29 80.94 60 47.46 60.76
75 33.95 45.25 90 20.87 27.50 105 9.60 11.45 120 1.67 2.36
[0223]
17TABLE XVI % Remaining Water on Sample # IM 32994 (duplicate
testing) time intervals in minutes % water on fabric 0 145.78 96.63
15 130.58 86.81 30 123.16 81.20 45 115.78 74.02 60 103.56 65.87 75
95.02 60.43 90 84.76 54.71 105 75.78 46.20 120 66.91 38.37
[0224]
18TABLE XVII % Remaining Water (average face & back) on Fabric
4/1 Time Intervals in Minutes % Water on Fabric 0 30.43 15 20.26 30
13.93 45 8.07 60 5.01 75 3.70 90 2.66 105 2.40 120 2.30
[0225]
19TABLE XVIII Remaining Water (average face & back) on Fabric
4/2 Time Intervals in Minutes % water on Fabric 0 29.62 15 17.12 30
11.08 45 5.92 60 3.49 75 2.70 90 2.63 105 2.33 120 2.21
[0226]
20TABLE XIX % Remaining Water (average face & back) on Fabric
4/3 Time Intervals in Minutes % Water on Fabric 0 31.48 15 20.28 30
14.96 45 10.29 60 7.23 75 5.21 90 3.91 105 3.05 120 2.51
[0227]
21TABLE XX % Remaining water (average face & back) on fabric
4/4 Time Intervals in Minutes % Water on Fabric 0 32.41 15 20.66 30
16.22 45 10.59 60 7.01 75 4.89 90 3.43 105 2.67 120 2.45
Results and Discussion
[0228] Despite the limited number of samples tested, there seems to
be a strong indication that printing a FC on 100% cotton fabric
does indeed reduce the overall water uptake. This results in even
faster drying times treated 100% cotton than for some of the
synthetics. Interestingly, it seems that not all synthetics absorb
and dry at the same rate, but that fabric thickness and
construction apparently are also important factors.
[0229] Variations of initial % WPU values after the "wetting out"
process in the Unimac can be observed within the different 100%
polyester fabric sets. Fluctuations are less noticeable for
synthetic fabrics and yellow polyester. The % WPU values for the FC
printed 100% cotton fabrics were also very reproducible and did not
deviate a lot within data sets.
[0230] Modification and variation of the methods and compositions
described above will be obvious in view of the description of the
invention. Such modifications are intended to be within the scope
of the claim.
* * * * *