U.S. patent application number 10/463558 was filed with the patent office on 2004-04-15 for methods for improving dimensional stability and/or durable press properties of elastic fabrics and elastic fabrics with improved properties.
Invention is credited to Miller, Larry Eugene, Osborne, Eva F., Tomasulo, Antonietta.
Application Number | 20040068802 10/463558 |
Document ID | / |
Family ID | 29736636 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040068802 |
Kind Code |
A1 |
Miller, Larry Eugene ; et
al. |
April 15, 2004 |
Methods for improving dimensional stability and/or durable press
properties of elastic fabrics and elastic fabrics with improved
properties
Abstract
Methods for providing elastic fabric comprising synthetic
elastic fibers and natural fibers with improved dimensional
stability or improved durable press while maintaining stretch
recovery properties comprise treating the fabric with a treatment
composition comprising formaldehyde and a catalyst for crosslinking
the formaldehyde with natural fibers in the fabric, and processing
the treated fabric to effect crosslinking of the formaldehyde and
to maintain stretch performance properties. Fabrics comprising
synthetic elastic fibers and natural fibers exhibiting improved
dimensional stability and/or durable press properties in
combination with additional advantageous properties are
produced.
Inventors: |
Miller, Larry Eugene;
(Cincinnati, OH) ; Osborne, Eva F.; (New Smyrna
Beach, FL) ; Tomasulo, Antonietta; (Hoboken,
NJ) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY
INTELLECTUAL PROPERTY DIVISION
WINTON HILL TECHNICAL CENTER - BOX 161
6110 CENTER HILL AVENUE
CINCINNATI
OH
45224
US
|
Family ID: |
29736636 |
Appl. No.: |
10/463558 |
Filed: |
June 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60389413 |
Jun 17, 2002 |
|
|
|
Current U.S.
Class: |
8/115.51 |
Current CPC
Class: |
D06M 15/643 20130101;
D06M 2200/20 20130101; D06M 2200/45 20130101; D06M 15/39 20130101;
D06M 13/127 20130101; D06M 13/12 20130101 |
Class at
Publication: |
008/115.51 |
International
Class: |
D06M 010/00 |
Claims
What is claimed is:
1. A method for providing elastic fabric comprising synthetic
elastic fibers and natural fibers with improved dimensional
stability while maintaining stretch recovery properties of the
fabric, comprising treating elastic fabric comprising synthetic
elastic fibers and natural fibers with a treatment composition
comprising formaldehyde and a catalyst for crosslinking the
formaldehyde with the natural fibers in the fabric, and processing
the treated fabric to effect crosslinking of the formaldehyde and
to maintain stretch performance properties.
2. A method according to claim 1, wherein the treatment composition
further comprises a silicone elastomer or a precursor thereof.
3. A method according to claim 2, wherein the fabric comprises from
about 0.5% to about 20% by weight of the synthetic elastic
fibers.
4. A method according to claim 2, wherein the synthetic elastic
fibers comprise at least about 85% of a segmented polyurethane.
5. A method according to claim 2, wherein the fabric comprises at
least about 20% by weight of the natural fibers.
6. A method according to claim 2, wherein the natural fibers
comprise cellulosic fibers selected from the group consisting of
cotton, linen, flax, rayon, cellulose acetate, cellulose
triacetate, hemp and ramie fibers.
7. A method according to claim 2, wherein the treatment composition
is free of aminoplast resin.
8. A method according to claim 2, wherein the resulting fabric
exhibits a length dimensional change and a width dimensional change
of less than about 5% each after the fabric has been aqueous
laundered one time.
9. A method according to claim 2, wherein the resulting fabric
exhibits a fabric growth of not greater than about 5% after the
fabric has been stretched at least about 80%.
10. A method for providing elastic fabric comprising synthetic
elastic fibers and natural fibers with improved durable press while
maintaining stretch recovery properties of the fabric, comprising
treating elastic fabric comprising synthetic elastic fibers and
natural fibers with a treatment composition comprising formaldehyde
and a catalyst for crosslinking the formaldehyde with the natural
fibers in the fabric, and processing the treated fabric to effect
crosslinking of the formaldehyde and to maintain stretch
performance properties.
11. A method according to claim 10, wherein the treatment
composition further comprises a silicone elastomer or a precursor
thereof.
12. A method according to claim 11, wherein the fabric comprises
from about 0.5% to about 20% by weight of the synthetic elastic
fibers.
13. A method according to claim 11, wherein the synthetic elastic
fibers comprise at least about 85% of a segmented polyurethane.
14. A method according to claim 11, wherein the fabric comprises at
least about 20% by weight of the natural fibers.
15. A method according to claim 11, wherein the natural fibers
comprise cellulosic fibers selected from the group consisting of
cotton, linen, flax, rayon, cellulose acetate, cellulose
triacetate, hemp and ramie fibers.
16. A method according to claim 11, wherein the treatment
composition is free of aminoplast resin.
17. A method according to claim 11, wherein the resulting fabric
exhibits a durable press value of at least about 3.0 after the
fabric has been aqueous laundered one time.
18. A method according to claim 11, wherein the resulting fabric
exhibits a fabric growth of not greater than about 5% after the
fabric has been stretched at least about 80%.
19. Fabric comprising synthetic elastic fibers and natural fibers
and exhibiting a durable press value of at least about 3.0 after
the fabric has been aqueous laundered one time.
20. Fabric according to claim 19, wherein the fabric exhibits a
fabric growth of not greater than about 5% after the fabric has
been stretched at least about 80%.
21. Fabric comprising synthetic elastic fibers and natural fibers
and exhibiting a length dimensional change and a width dimensional
change of less than about 5% each after the fabric has been aqueous
laundered one time.
22. Fabric according to claim 21, wherein the fabric exhibits a
fabric growth of not greater than about 5% after the fabric has
been stretched at least about 80%.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Application Serial No. 60/389,413, filed
Jun. 17, 2003.
FIELD OF THE INVENTION
[0002] This invention relates to methods for providing elastic
fabrics comprising synthetic elastic fibers and natural fibers and
having improved dimensional stability and/or durable press
properties, particularly while maintaining good stretch recovery of
the fabrics. This invention also relates to elastic fabrics which
have improved dimensional stability and/or improved durable press
properties, particularly wherein the fabrics comprise synthetic
elastic fibers and natural fibers.
BACKGROUND OF THE INVENTION
[0003] Many fabrics, comprising natural fibers do not possess
durable press (or "wash and wear" or "smooth-dry") performance or
dimensional stability, i.e., shrinkage resistance. Cellulosic
fabrics, such as fabrics containing cotton, for instance, have been
treated with aminoplast resins, including N-methylol cross-linking
resins such as dimethylol dihydroxyethyleneurea (DMDHEU) or
dimethylol propylcarbamate (DMPC), to impart durable press
properties, as disclosed, for example, in the Martin et al U.S.
Pat. No. 4,521,176. Unfortunately, many reacted aminoplast resins
break down during storage, thus releasing formaldehyde. The
formaldehyde release may occur not only throughout the preparation
of the fabric but also during garment-making. Further, garments or
fabrics treated with aminoplast resins may release additional
formaldehyde when stored under humid conditions. Aminoplast resins
may also hydrolyze during washing procedures, resulting in a loss
of the durable press performance. Additionally, aminoplast resins
tend to give fabric a harsher handle, that is, make the fabric feel
less soft. As the resins make the fabric feel less soft, the fabric
must be treated with additional softeners, for example silicone
softeners. Unfortunately, the silicone softeners tend to make the
fabric hydrophobic although it is often preferred that the fabric
have hydrophilic properties.
[0004] Cellulosic fibers have also been cross-linked with
formaldehyde to impart durable press properties. For example, the
Payet U.S. Pat. Nos. 3,960,482, 3,960,483, 4,067,688 and 4,104,022
disclose durable press processes which comprise impregnating a
cellulosic fiber-containing fabric with an aqueous solution
comprising a catalyst, and, while the fabric has a moisture content
of above 20% by weight, exposing the fabric to formaldehyde vapors
and curing under conditions at which formaldehyde reacts with the
cellulose. The Payet U.S. Pat. No. 4,108,598 discloses a process
which comprises treating cellulosic fiber-containing fabrics with
an aqueous solution of formaldehyde and a catalyst, heat curing the
treated fabric by introducing the fabric into a heating zone, and
gradually increasing the temperature of the heating zone, thereby
increasing the temperature of the heated fabric to prevent the loss
of an amount of formaldehyde which will reduce the overall extent
of curing. The Payet U.S. Pat. No. 5,885,303 also discloses a
durable press process for cellulosic fiber-containing fabrics. The
process comprises treating the fabric with an aqueous solution of
formaldehyde, a catalyst capable of catalyzing the cross-linking
reaction between formaldehyde and cellulose, and an effective
amount of a silicone elastomer to reduce loss in tear strength in
the treated fabric. Formaldehyde is generally less expensive than
aminoplast resins, and formaldehyde treatment of cellulosic fabrics
typically results in durable press properties which are more
durable than those obtained by aminoplast resins.
[0005] Many consumers also prefer garments containing synthetic
elastic fibers and/or garments comprising a blend of synthetic
elastic fibers and natural fibers such as, for instance, spandex
blend knit and/or woven fabrics. Fabrics containing synthetic
elastic fibers have the ability to be stretched repeatedly and
still recover to very near their original length and/or shape. Such
fabrics are often incorporated in garments which comfortably
conform to the consumer's body without bagging and/or sagging.
However, these fabrics often undesirably exhibit noticeable
shrinking and/or wrinkling after aqueous laundering, and it is
difficult to find means for overcoming the disadvantages while
maintaining the desirable elastic properties of such fabrics.
Additionally, the life expectancy of garments made of these fabrics
is often decreased by repeated heat treatments used during
manufacturing and/or home care procedures, as combinations of heat
and tension accelerate the fabric growth of elastic fabrics thereby
resulting in an unacceptable fit and/or appearance.
[0006] Accordingly, there is a continuing need to further improve
individual characteristics of elastic fabrics containing a blend of
synthetic elastic fibers and natural fibers and to improve the
overall combinations of properties exhibited by such fabrics.
SUMMARY OF THE INVENTION
[0007] Accordingly, it is an object of the present invention to
obviate problems of the prior art. It is a further object of the
present invention to provide methods for improving the dimensional
stability and/or durable press properties of fabrics and
particularly to improve the dimensional stability and/or durable
press properties of elastic fabrics containing synthetic elastic
fibers and natural fibers, while maintaining stretch recovery of
the fabrics. It is a related object to provide methods for
preparing elastic fabrics which exhibit advantageous combinations
of properties and which are suitable for aqueous washing or
laundering, and to provide elastic fabrics exhibiting such
advantageous properties.
[0008] These and additional objects are provided by the methods and
fabrics of the invention. In one embodiment, the invention is
directed to methods for providing elastic fabric comprising
synthetic elastic fibers and natural fibers with improved
dimensional stability while maintaining stretch recovery properties
of the fabric. The methods comprise treating elastic fabric
comprising synthetic elastic fibers and natural fibers with a
treatment composition comprising formaldehyde, and a catalyst for
crosslinking the formaldehyde with natural fibers in the fabric,
and processing the treated fabric to effect crosslinking of the
formaldehyde and to maintain stretch performance properties.
According to more specific embodiments, the treated fabrics are
processed under controlled conditions such as, for instance,
temperature, time and tension levels.
[0009] In another embodiment, the invention is directed to methods
for providing elastic fabric comprising synthetic elastic fibers
and natural fibers with improved durable press while maintaining
stretch recovery properties of the fabric. The methods comprise
treating elastic fabric comprising synthetic elastic fibers and
natural fibers with a treatment composition comprising formaldehyde
and a catalyst for crosslinking the formaldehyde with natural
fibers in the fabric, and processing the treated fabric to effect
crosslinking of the formaldehyde and to maintain stretch
performance properties. According to more specific embodiments, the
treated fabrics are processed under controlled conditions such as,
for instance, temperature, time and tension levels.
[0010] In yet additional embodiments, the invention is directed to
fabric comprising synthetic elastic fibers and natural fibers and
exhibiting a durable press value of at least about 3.0 after the
fabric has been aqueous laundered one time, and to fabric
comprising synthetic elastic fibers and natural fibers and
exhibiting a length dimensional change and a width dimensional
change of less than about 5% each after the fabric has been aqueous
laundered one time.
[0011] The methods of the invention are advantageous in providing
fabrics which exhibit improved dimensional stability and/or durable
press properties, while maintaining stretch recovery
properties.
[0012] These and additional aspects, objects and advantages of the
invention are more fully described in the detailed description.
DETAILED DESCRIPTION
[0013] The present invention is directed to methods for providing
fabrics, particularly elastic fabrics comprising synthetic elastic
fibers and natural fibers, with improved dimensional stability
and/or good durable press properties while maintaining stretch
recovery properties. This invention also relates to elastic fabrics
comprising synthetic elastic fibers and natural fibers and
exhibiting good durable press and/or dimensional stability even
after aqueous laundering.
[0014] As used herein, "dimensional stability" refers generally to
the ability of a fabric to resist dimensional change, particularly
after aqueous laundering. As employed in the present invention,
improved dimensional stability indicates that the fabric exhibits a
dimensional change in length and width, after the fabric has been
aqueous laundered one time, less than that exhibited by the
untreated fabric after one aqueous laundering.
[0015] As used herein, "stretch recovery" refers generally to the
ability of a fabric to substantially recover to very near its
original length and/or shape after being stretched, particularly
such that the fabric does not retain a permanent deformation. As
used herein, "permanent deformation" refers generally to the
ability of a fabric to retain a permanent length and/or shape after
being stretched such that the fabric does not recover back to or
near the original fabric dimensions exhibited prior to stretching
the fabric. In one embodiment, the resulting fabrics according to
the present invention exhibit a fabric growth of not greater than
about 5% after the fabric has been stretched at least about 80% of
its maximum stretch under a four pound load according to ASTM D
3107. As used herein, "fabric stretch" refers generally to the
increase in length of a specimen of fabric resulting from a load
applied under specified conditions (specified tension) and "fabric
growth" refers generally to the difference between the original
length of a specimen and its length after application of a
specified tension for a prescribed time and the subsequent removal
of the tension.
[0016] The fabrics employed in the present invention comprise
synthetic elastic fibers and natural fibers. As used herein,
"fiber" refers generally to a generic term for any one of the
various types of matter that form the basic elements of a textile
and that is characterized by having a length at least 100 times
greater than its diameter. As used herein, "filament" refers
generally to a continuous fiber of extremely long length, whereas a
"staple" refers generally to a natural fiber of cut lengths from a
filament and "tow", refers to a coarse and/or broken fiber and/or
filament.
[0017] As used herein, "yam" refers to a continuous strand of
textile fibers, generally filaments, and/or materials in a form
suitable for knitting, weaving or otherwise intertwining for a
textile fabric. As used herein, "fabrics" generally refer to
knitted fabrics, woven fabrics, or non-woven fabrics prepared from
yarns or fibers, while "garments" generally refer to wearable
articles comprising fabrics, including, but not limited to, shirts,
blouses, dresses, pants, sweaters and coats. Non-woven fabrics
include textile structures produced by bonding or interlocking of
fibers, or both, accomplished by a mechanical, chemical, thermal,
or solvent means and combinations thereof. "Textiles", includes
fabrics, yarns, and articles comprising fabrics and/or yarns, such
as garments, home goods, including, but not limited to, bed and
table linens, draperies and curtains, and upholsteries, and the
like.
[0018] As used herein, "natural fibers" refer to fibers which are
obtained from natural sources, such as cellulosic fibers and
protein fibers, or which are formed by the regeneration of or
processing of natural occurring fibers and/or products. Natural
fibers are not intended to include fibers formed from petroleum
products. Natural fibers include fibers formed from cellulose, such
as cotton fiber and regenerated cellulose fiber, commonly referred
to as rayon, or acetate fiber derived by reacting cellulose with
acetic acid and acetic anhydride in the presence of sulfuric acid.
As used herein, "natural fibers", are intended to include natural
fibers in any form, including individual filaments, and fibers
present in yarns, fabrics and other textiles, while "individual
natural fibers" is intended to refer to individual natural
filaments.
[0019] As used herein, "thermoplastic fiber" refers generally to a
class name for various genera of filament, tow, or staple produced
from a fiber forming substance which is synthesized from a chemical
compound.
[0020] As used herein, "cellulosic fibers" are intended to refer to
fibers comprising cellulose, and include, but are not limited to,
cotton, linen, flax, rayon, cellulose acetate, cellulose
triacetate, hemp and ramie fibers. As used herein, "rayon fibers"
is intended to include, but is not limited to, fibers comprising
viscose rayon, high wet modulus rayon, cuprammonium rayon,
saponified rayon, modal rayon and lyocell rayon. "Protein fibers",
are intended to refer to fibers comprising proteins, and include,
but are not limited to, wools, such as sheep wool, alpaca, vicuna,
mohair, cashmere, guanaco, camel and llama, and silks.
[0021] As used herein, "synthetic fibers" refer to those fibers
which are not prepared from naturally occurring filaments and
include, but are not limited to, fibers formed of synthetic
materials such as polyesters, polyamides such as nylons,
polyacrylics, and polyurethanes such as spandex. Synthetic fibers
include fibers formed from petroleum products. As used herein,
"synthetic elastic fibers" are those fibers which form "synthetic
elastic yarns", such as nontextured yams which can be stretched
repeatedly at room temperature to at least twice their original
length and which after removal of the tensile force will
immediately and forcibly return to approximately their original
length. According to the present invention, synthetic elastic
fibers include, but are not limited to, elastane fibers (i.e.,
Spandex). As is used herein, "spandex" and "elastane" fibers both
refer generally to manufactured fibers in which the fiber forming
substance is a long-chain synthetic polymer comprised of at least
85% of a segmented polyurethane.
[0022] Elastic fabrics for use in the present invention comprise a
textile product made from synthetic elastic fibers and/or synthetic
elastic yams either alone or in combination with other textile
materials. Additionally, the elastic fabrics may be in the form of
garments or other textiles comprising synthetic elastic fibers and
natural fibers. In one embodiment, the fabrics comprise at least
about 20% by weight of natural fibers, such as cotton fibers, rayon
fibers or the like. In additional embodiments, the fabrics comprise
from about 0.5% to about 20% by weight of synthetic elastic
fibers.
[0023] While not being bound by theory, it is believed that when
elastic fabrics containing natural fibers are treated with a
composition comprising formaldehyde and a catalyst capable of
cross-linking formaldehyde with a natural fiber, a chemical
modification of the natural fibers occurs. It is believed that the
formaldehyde reacts chemically with the natural fibers to
cross-link the individual polymer chains of the natural fibers,
thereby improving various fabric performance properties, such as
for instance, durable press properties and/or dimensional
stability, i.e., reduced dimensional change. Surprisingly, the
elastic fabrics treated according to the present methods maintain
their stretch performance properties, i.e., the fabrics remain
elastic and exhibit good stretch recovery. This is surprising as
one might expect that the crosslinking which provides improved
dimensional stability and/or durable press would disadvantageously
limit the elasticity, and specifically the stretch ability and
stretch recovery properties, of the fabric. In accordance with the
present methods, a silicone elastomer or precursor thereof may also
be included in the formaldehyde treatment to provide additional
desirable properties, for example good strength and/or tear
strength, water absorbency and the like. The processes of the
present invention are also advantageous in providing fabrics
exhibiting reduced drying time, improved fibrillation resistance
and/or pill resistance and improved brightness.
[0024] To provide the crosslinked formaldehyde treatment, the
fabric is treated with a treatment composition comprising
formaldehyde and a catalyst followed by drying and/or curing of the
treated fabric. In a more specific embodiment, the treatment
composition further comprises a silicone elastomer or a precursor
thereof. Formaldehyde is generally available in an aqueous
solution, referred to as formalin, comprising water, about 37% by
weight formaldehyde, and generally about 10% to 15% by weight
methanol. Formaldehyde may also be generated in an aqueous treating
solution in situ by adding paraformaldehyde (polyoxymethylene) to
water, thereby generating formaldehyde.
[0025] The amount of formaldehyde in the treatment composition is
sufficient to impart improved dimensional stability and/or improved
durable press, while maintaining stretch recovery properties. In
further embodiments, additional desirable properties are also
provided. The amount of formalin useful for imparting the above
mentioned properties according to the present invention is
typically dependent upon the cellulosic content of the fabric. In
exemplary embodiments, the fabric is treated with at least about 1%
by weight formalin, and specifically with from about 2% to about
22% by weight formalin, based on the weight of the fabric. In one
embodiment, for example wherein the fabric comprises cotton fibers,
the fabric is treated with about 5% to about 8% formalin, based on
the weight of the fabric. In another embodiment, for example
wherein the fabric comprises rayon fibers, the fabric is treated
with from about 12% to about 20% by weight formalin, based on the
weight of the fabric. In yet another embodiment, for example
wherein the nonelastic fibers in the fabric comprise a 50/50
rayon/polyester blend, the fabric is treated with from about 12% to
about 20%, more specifically about 16%, by weight formalin, based
on the weight of the fabric. While "formalin" refers to an aqueous
solution comprising 37%, by weight, formaldehyde, as will be
apparent to one of skill in the art, formaldehyde solutions
comprising levels of formaldehyde other than 37%, by weight, may
also be used. Using the above ranges of formalin, the fabric is
treated with actual formaldehyde, as opposed to formalin, at a
level of from about 0.5% to about 8%, specifically from about 1% to
about 7%, based on the weight of the fabric. Thus, in one
embodiment, for example wherein the fabric comprises cotton fibers,
the fabric is treated with about 1% to about 3% formaldehyde, as
opposed to formalin, based on the weight of the fabric. In another
embodiment, for example wherein the fabric comprises rayon fibers,
the fabric is treated with from about 5% to about 7% by weight
formaldehyde, as opposed to formalin, based on the weight of the
fabric. In yet another embodiment, wherein the nonelastic fibers in
the fabric comprise a 50/50 rayon/polyester blend, the fabric is
treated with about 4% to about 7% by weight formaldehyde, as
opposed to formalin, based on the weight of the fabric.
[0026] Suitable catalysts are those capable of catalyzing a
cross-linking reaction between formaldehyde and a natural fiber,
and specifically are catalysts capable of catalyzing the
cross-linking of formaldehyde with a natural fiber comprising
hydroxy groups, such as cellulosic fibers. Catalysts which may be
used include mineral acids, organic acids, salts of strong acids,
ammonium salts, alkylamine salts, metallic salts and combinations
thereof. In one embodiment the catalyst is other than a mineral
acid.
[0027] Suitable mineral acid catalysts include hydrochloric acid,
sulfuric acid, nitric acid, phosphoric acid and boric acid.
Suitable organic acids include oxalic acid, tartaric acid, citric
acid, malic acid, glycolic acid, methoxyacetic acid, chloroacetic
acid, lactic acid, 3-hydroxybutyric acid, methane sulfonic acid,
ethane sulfonic acid, hydroxymethane sulfonic acid, benzene
sulfonic acid, p-toluene sulfonic acid, cyclopentane
tetracarboxylic acid, butane tetracarboxylic acid,
tetrahydrofuran-tetracarboxylic acid, nitrilotriacetic acid, and
ethylenediaminetetraacetic acid. Suitable salts of strong acids
include sodium bisulfate, sodium dihydrogen phosphate and disodium
hydrogen phosphate. Suitable ammonium salts include ammonium
chloride, ammonium nitrate, ammonium sulfate, ammonium bisulfate,
ammonium dihydrogen phosphate and diammonium hydrogen phosphate.
Suitable alkanolamine salts include the hydrochloride, nitrate,
sulfate, phosphate and sulfamate salts of
2-amino-2-methyl-l-propanol, tris (hydroxymethyl) aminomethane and
2-amino-2-ethyl-1-3-propanediol. Suitable metal salts include
aluminum chlorohydroxide, aluminum chloride, aluminum nitrate,
aluminum sulfate, magnesium chloride, magnesium nitrate, magnesium
sulfate, zinc chloride, zinc nitrate and zinc sulfate, and mixtures
thereof.
[0028] In one embodiment of the invention, the catalyst is a halide
or nitrate salt of zinc or magnesium, and preferably the catalyst
is magnesium chloride. An organic acid, such as citric acid, may be
used in combination with the halide or nitrate salt of zinc or
magnesium. Generally the molar ratio of metal salt to organic acid
is from about 5:31 to about 20:1. In one embodiment, the catalyst
comprises magnesium chloride and citric acid, while in another
embodiment the catalyst comprises magnesium chloride and aluminum
chloride.
[0029] The fabric is typically treated with an amount of catalyst
sufficient to catalyze cross-linking of the natural fibers by the
formaldehyde to provide improved dimensional stability and/or
improved durable press while maintaining stretch recovery
properties. In one embodiment, the catalyst may be employed in an
amount sufficient to provide a formaldehyde:catalyst weight ratio
of from about 10:1 to about 1:10, and specifically from about 5:1
to about 1:5.
[0030] The formaldehyde treatment composition may comprise, by
weight, up to about 12% of a catalyst solution, and specifically
from about 1% to about 9% of a catalyst solution. Generally the
catalyst solution comprises from about 20% to about 50%, by weight
catalyst. In one embodiment, for example wherein the elastic fabric
comprises cotton fibers, the treatment solution comprises from
about 2 to about 4% by weight of a catalyst solution comprising
about 30% by weight catalyst, and in another embodiment, for
example wherein the elastic fabric comprises rayon fibers, the
treatment solution comprises from about 6% to about 8% by weight of
a catalyst solution comprising about 30% by weight catalyst. In yet
a further embodiment, the catalyst solution comprises about 40%, by
weight, magnesium chloride, for a final magnesium chloride level of
up to about 5%, by weight of the treatment solution. Suitable
catalyst solutions include FREECAT.RTM. LF (magnesium chloride and
citric acid) and FREECAT.RTM. No. 9 (aluminum chloride and
magnesium chloride), commercially available from B. F.
Goodrich.
[0031] The formaldehyde treatment composition typically comprises a
liquid carrier, preferably water, although, as noted above, the
formalin used to prepare the treatment composition may comprise
small amounts of organic solvents such as methanol or the like. In
one embodiment, the treatment composition is free of any organic
solvents other than that present in the formalin or the catalyst
solution. In another embodiment, the carrier may comprise
pentamethylcyclosiloxane.
[0032] According to exemplary embodiments of the present invention,
a silicone elastomer or precursor thereof may be further included
in the formaldehyde-containing treatment composition with which the
fabric is treated. According to these embodiments, the formaldehyde
treatment composition comprises formaldehyde, catalyst and silicone
elastomer or a precursor thereof. The combination of a silicone
elastomer or precursor thereof and the formaldehyde-containing
treatment composition provides the fabric with good strength and/or
water absorbency, while also providing good durable press and/or
shrinkage resistance properties. The good water absorbency is
remarkable in that many conventional durable press and/or shrinkage
resistance treatments render the treated fabrics hydrophobic. The
good strength is evident in a reduction of the loss in tear and
tensile strength that typically occurs during formaldehyde
cross-linking of fibers.
[0033] Various silicone elastomers are known in the art and are
suitable for use in the methods and fabrics of the invention. In
one embodiment, the silicone elastomer is a polysiloxane.
Similarly, the silicone elastomer precursor which forms an
elastomer upon curing, typically by self curing, may be a
polysiloxane. Elastomers are polymers which are capable of being
stretched with relatively little applied force, and which return to
the unstretched length when the force is released. Silicone
elastomers have a backbone made of silicon and oxygen with organic
substituents attached to silicon atoms, with a number n of
repeating units of the general formula: 1
[0034] The groups R and R' are each independently selected from
lower alkyls, preferably C.sub.1-C.sub.3 alkyls, phenyl, or lower
alkyls or phenyls comprising a group reactive to cellulose, such as
hydroxy groups, halogen atoms, for example, fluoride, or amino
groups. Suitable elastomers include those disclosed in U.S. Pat.
No. 5,885,303, incorporated herein by reference.
[0035] A preferred silicone elastomer or precursor composition
comprises up to about 60%, by weight, silicone solids. In one
embodiment, the silicone elastomer or precursor composition
comprises from about 20% to about 60%, specifically from about 30%
to about 60%, by weight of silicone solids, while in another
embodiment the silicone elastomer or precursor composition
comprises from about 20% to about 30% by weight of silicone solids.
Suitable silicone elastomer precursors include a dimethyl silicone
emulsion containing from about 30% to about 60%, by weight,
silicone solids, commercially available as SM2112 from General
Electric. Another suitable commercially available elastomer
precursor is Sedgesoft ELS from Sedgefield Specialties, containing
from about 24% to about 26%, by weight, silicone solids.
[0036] When the silicone elastomer or precursor thereof is applied
to the fabric with a liquid formaldehyde treatment composition, the
liquid treatment composition may comprise up to about 4%,
specifically from about 0.1% to about 2.5%, more specifically from
about 0.2% to about 2%, by weight of the elastomer or precursor
solids. In one embodiment, the treatment composition comprises from
about 0.2% to about 2%, specifically from about 0.6% to 1.2%, by
weight silicone solids, while in another embodiment, the
composition comprises from about 0.2% to about 0.8% by weight
silicone solids.
[0037] The formaldehyde treatment composition may be applied to the
fabric in accordance with any of the conventional techniques known
in the art. In one embodiment, a liquid treatment composition may
be applied to the fabric by saturating the fabric in a trough and
squeezing the saturated fabric through pressure rollers to achieve
a uniform application (padding process). As used herein "wet
pick-up" refers to the amount of treatment composition applied to
and/or absorbed into the fabric based on the original weight of the
fabric. "Original weight of the fabric" or simply "weight of the
fabric" refers to the weight of the fabric prior to its contact
with the treatment composition. For example, 50% pick-up means that
the fabric picks up an amount of treatment solution equal to 50% of
the fabric's original weight. In specific embodiments, the wet
pick-up is at least 20%, specifically from about 50% to 100%, more
specifically from about 65% to about 80%, by weight of the
fabric.
[0038] Other application techniques which may be employed include
kiss roll application, engraved roll application, printing, foam
finishing, vacuum extraction, spray application or any process
known in the art. Generally these techniques provide lower wet
pick-up than the padding process. The concentration of the
chemicals in the solution may be adjusted to provide the desired
amount of chemicals on the original weight of the fabric (OWF).
[0039] In a preferred embodiment, the formaldehyde treatment
composition is applied in an amount to insure a moisture content of
more than 20% by weight, specifically more than 30% by weight, on
the fabric before curing. Optionally, a wetting agent may be
included in the treatment composition to facilitate obtaining the
desired moisture content. Nonionic wetting agents are
preferred.
[0040] Once the treatment composition has been applied to the
fabric, the fabric is typically heated for a time and at a
temperature sufficient for the cross-linking of the natural fibers
with the formaldehyde. For example, the fabric may be heated at a
temperature greater than about 250.degree. F., specifically from
about 250.degree. F. to about 375.degree. F., in an oven for a
period of from about 10 seconds to about 15 minutes, specifically
from about 45 seconds to about 3 minutes, to react the formaldehyde
with the natural fibers in the fabric and affect crosslinking of
the formaldehyde and natural fibers to provide improved dimensional
stability and maintained stretch recovery properties together with
effects such as, durable press and/or shrinkage resistance. There
is an inverse relationship between curing temperature and curing
time, that is, the higher the temperature of curing, the shorter
the dwell time in the oven; conversely, the lower the curing
temperature, the longer the dwell time in the oven. Additionally,
the inventors of the present invention have unexpectedly discovered
that the treatment of the unique blend of synthetic elastic fibers
and natural fibers of the present fabrics minimizes up stream
processing normally incurred with relaxation, boil off and/or
jamming procedures for elastic fabrics containing spandex/elastane
fibers. As used herein, "relaxation", "boil off", and "jamming",
procedures each refer generally to thermal processes which employ
heat, moisture, and tension to maximize the physical contraction of
an elastic fiber. By minimizing such processing steps, the amount
of time required wherein the temperature is at or above about
120.degree. F. is reduced. Additionally, the jamming process may be
incorporated into the same procedure for the crosslinking process.
The single process flow procedure may then serve for multiple
finishing operations i.e., jamming, crosslinking, formaldehyde
removal, and heat setting. By consolidating these heat treating
procedures, the life of the fabric may be increased. Without being
bound by theory herein, the inventors therefore believe that the
abovementioned desirable properties exhibited by the fabrics of the
present invention are enhanced by the combination of both the
chemical and mechanical and/or procedural aspects of the processes
disclosed herein.
[0041] In another embodiment, the present invention comprises
methods for improving dimensional stability and/or durable press
while maintaining stretch recovery properties of fabric, wherein
the silicone elastomer may be included in the treated fabric by
means of a separate treatment step before or after the formaldehyde
crosslinking treatment. Additionally, if the silicone elastomer or
precursor thereof is applied to the fabric subsequent to treatment
with the formaldehyde crosslinking composition, the silicone
elastomer precursor thereof may be applied prior to or subsequent
to the processing step which is employed to affect curing of the
formaldehyde with the natural fibers of the fabric, although in
specific embodiments application prior to processing may be
desirable. The applied silicone elastomer or precursor thereof may
be dried, with self curing of the precursor being affected
thereby.
[0042] The fabrics according to the invention exhibit good durable
press properties and/or good shrink resistance. In one embodiment,
it is preferred that the fabric exhibit good durable press, for
example a DP (durable press) rating of at least about 3.0,
specifically at least about 3.5, as measured according to AATCC
Test Method 124-1996, after one aqueous washing, more specifically
after five aqueous washings, and/or good dimensional stability, for
example a dimensional change in length and width of less than about
5% each, specifically less than about 4.5% each, more specifically
less than about 4.0% each, and in certain embodiments, less than
about 3.0% each as measured according to AATCC Test Method
135-1995, after one machine washing, more specifically after five
aqueous washings. Shrinkage resistance and/or dimensional change
may also be measured according to AATCC Test Method 150-1995. In
further embodiments, the fabrics exhibit good filling tensile and
tear strengths, for example of at least about 25 pounds and at
least about 24 ounces, respectively, as measured according to ASTM
D-5035-95 for tensile strength, and ASTM D-2261-96 for tear
strength.
[0043] The fabrics according to the invention also exhibit
excellent smoothness appearance and appearance retention with usage
over time. Without being limited by theory herein, the present
inventors believe that the unique combination of properties for
formulating the elastic fabrics according to the present invention
can be used to produce fabrics with highly desirable feel and
appearance properties, which have been otherwise unattainable by
previously known methods. More particularly, it has been discovered
that elastic fabrics comprising a blend of synthetic elastic fibers
and natural fibers, can be used to produce garments that have
excellent stretch/recovery properties while minimizing unwanted
fabric growth according to ASTM Test Method D3107; have minimal
dimensional change over multiple washing cycles according to AATCC
Test Method 135; have improved color appearance after multiple
washings as rated by the AATCC Gray Scale for Color Change; resist
wrinkling to minimize the need for ironing according to ASTM Test
Method D2654; and dry in less time (i.e., about half the time of
conventional fabrics) to minimize the degradation of elastic fibers
therein according to ASTM Test Method D2654.
[0044] Furthermore, such fabrics avoid the cost and complexity
typically associated with previous production methods, particularly
during the preparation, dyeing and finishing steps which are
utilized to control jamming and/or the shrinkage of the fabrics.
These production benefits include, for instance, the elimination
and/or reduction of heat setting, scouring and/or cool down
processes typically found in previous fabric production techniques.
Moreover, the processes of the present invention produce fabrics
exhibiting reduced relaxation time, ply reduction and sectional
slitting typically required by most fabrics during garment
manufacturing, particularly as the sizing qualities of the fabrics
are improved through dimensional change reductions of cut pattern
pieces during garment production. Additionally, the fabrics have
various cutting room advantages such as, for instance, reduced
conditioning time, increased layering prior to cutting, improved
tolerance for fabric sizing, the elimination of cutting sections
for fabric relaxation and the ability to utilize less fabric than
traditionally needed during production processes to make the
garments. Moreover, and without being limited by theory herein, the
inventors believe that fabrics treated via the processes of the
present invention will have improved fabric handling
characteristics during storage, as such fabrics exhibit reduced
and/or eliminated bow and skew properties.
[0045] In a further embodiment, the fabrics according to the
invention exhibit good hand or softness, in the absence of
conventional softeners such as silicone or polyethylene softeners.
Typically, the fabrics will exhibit a low coefficient of friction
and/or a high flexibility/Instron softness.
[0046] In processes in accordance with the present invention,
unreacted formaldehyde remaining on the fabric is removed during
subsequent processing of the fabric. Generally, the final substrate
will comprise less than about 300 ppm formaldehyde, specifically
less than about 200 ppm formaldehyde, more specifically less than
about 100 ppm formaldehyde, and even more specifically less than
about 50 ppm formaldehyde, as measured according to AATCC Test
Method 112-1993.
[0047] Some polysiloxanes, generally referred to as silicone oils,
have a liquid form, are not elastomeric and do not self-crosslink.
Silicone oils include, for example, non-reactive linear
polydimethyl siloxanes, that is, siloxanes which are not capable of
further reaction with other silicones and are not capable of a self
curing reaction. Silicone oils have a tendency to produce
non-removable spots on fabrics. In contrast, the silicone
elastomers used in the present invention generally do not produce
such spots. Although the fabrics or treatment compositions may
comprise silicone oil, in one embodiment, the fabrics and treatment
compositions are substantially free of, and specifically are free
of, silicone oil. As used herein, substantially free of silicone
oils means the treatment compositions and fabrics comprise less
than 1%, by weight, silicone oil.
[0048] Thermosetting resins used to impart durable press properties
to fabrics are generally aminoplast resins which are the products
of the reaction of formaldehyde with compounds such as urea,
thiourea, ethylene urea, dihydroxyethylene urea and melamines. As
used herein "aminoplast resins" is intended to include
N-methylolamide cross-linking agents such as dimethylol
dihydroxyethylene urea, dimethylol urea, dimethylolethylene urea,
dimethylol propylene urea, dimethylol methyl carbamate, dimethylol
n-propylcarbamate, dimethylol isopropylcarbamate trimethylolated
melamine, and tris(methoxymethol) melamine. Specifically, the
fabrics, methods and formaldehyde treatment compositions of the
invention are substantially free of, and more specifically are free
of, aminoplast resins and N-methylol cross-linking agents. As used
herein, "substantially free" of aminoplast resins and N-methylol
cross-linking agents is intended to mean the fabrics and treatment
solutions comprise less than about 0.5%, by weight, aminoplast
resin or methylol cross-linking agent.
[0049] Prior to treatment with the formaldehyde composition and
silicone elastomer or precursor thereof, the fabric may optionally
be prepared using any fiber, yarn, or textile pre-treatment
preparation techniques known in the art. Suitable preparation
techniques include brushing, singeing, desizing, scouring,
mercerizing, and bleaching. For example, fabric may be treated by
brushing which refers to the use of mechanical means for raising
surface fibers which will be removed during singeing. The fabric
may be then be singed using a flame to bum away fibers and fuzz
protruding from the fabric surface. Textiles may be desized, which
refers to the removal of sizing chemicals such as starch and/or
polyvinyl alcohol, that are put on yarns prior to weaving to
protect individual yarns. The fabrics may be scoured, which refers
to the process of removing natural impurities such as oils, fats
and waxes and synthetic impurities such as mill grease from
fabrics. Mercerization refers to the application of high
concentrations of sodium hydroxide to a fabric to alter the
morphology of fibers, particularly cotton fibers. Fabrics may be
mercerized to improve fabric stability and luster. Finally,
bleaching refers to the process of destroying any natural color
bodies within the natural fiber. A typical bleaching agent is
hydrogen peroxide.
[0050] The various preparation techniques are optional and
dependent upon the desired final product. For example, when the
final fabric is to be dyed a dark color, there may be no need to
bleach the substrate. Similarly, there may be no need to desize a
knit which was prepared without using any sizing agents, and no
need to separately scour knits and woven textiles as the scouring
may be done during bleaching.
[0051] The following examples are set forth to demonstrate the
methods of the present invention and the improved dimensional
stability and/or durable press properties together with maintained
stretch recovery properties which are obtained in elastic fabrics
by the methods of the present invention. Throughout the examples
and the present specification, parts and percentages are by weight
unless otherwise specified. The following examples are illustrative
only and are not intended to limit the scope of the methods and
fabrics of the invention as defined by the claims.
EXAMPLE 1
[0052] In this example, elastic fabric samples are provided with a
formaldehyde crosslinking treatment in accordance with the
invention. According to this example, an elastic fabric comprising
97% rayon and 3% spandex is treated with from about 15% to about
22% by weight of formalin (37% formaldehyde), from about 3% to
about 6% of a catalyst solution, and from about 0.1% to about 1.5%
of silicone elastomer solids.
EXAMPLE 2
[0053] In this example, elastic fabric samples are provided with a
formaldehyde crosslinking treatment in accordance with the
invention. According to this example, an elastic fabric comprising
65% cotton, 32% rayon and 3% spandex, is treated with from about
15% to about 18% by weight of formalin (37% formaldehyde), about 3%
of a catalyst solution, and about 1% silicone elastomer solids.
[0054] The examples and specific embodiments set forth herein are
for illustrative purposes only and are not intended to limit the
scope of the methods and fabrics of the invention Additional
methods and fabrics within the scope of the claimed invention will
be apparent to one of ordinary skill in the art in view of the
teachings set forth herein.
* * * * *