Field of invention
[0001] This invention relates to a durable press/wrinkle-free process for cellulosic fiber-containing
fabrics and more particularly to a process which permits high treatment level amounts
of formaldehyde and catalysts to impart wrinkle resistance to the cellulosic fiber-containing
fabrics while reducing the loss in both tensile and tear strength normally associated
with such treatment processes.
Description of related art
[0002] There are a number of known process for treating cellulosic fiber-containing fabrics,
such as cotton-containing fabrics, to make them wrinkle-free. These treatment processes
include resin or polymer treatment of the fabric, but these are costly and unsatisfactory.
Another process for treating cellulosic fiber-containing products relies on formaldehyde
to provide durable crosslinking of the cellulose molecules and to thereby impart durable
crease resistant and smooth drying characteristics to these products. However, problems
have been encountered with the known processes. A simple, reproducible, completely
satisfactory low-cost formaldehyde durable press process has not yet been achieved.
[0003] It has long been known to treat cellulosic materials with formaldehyde, as is evidenced
by
U.S. Patent Number 2,243,765. This patent describes a process for treating cellulose with an aqueous solution
of formaldehyde containing a small proportion of an acid catalyst under such conditions
of time and temperature that the reaction is allowed to approach its equilibrium.
It is further stated that, in carrying out this process, the proportion of the solution
of formaldehyde to the cellulose must be at least such that the cellulose is always
in a fully swollen state. It is also stated that the time and temperature of the treatment
with the solution of formaldehyde and acid catalyst will vary with one another, the
time required increasing rapidly as the temperature diminishes. When it is desired,
the product may be isolated by washing and drying; preferably at a temperature of
about 135.55°C (about 212°F). The products obtained according to this process are
said to show no increase in wet strength and possess a high water imbibition, an increased
resistance to creasing and a slight increase in affinity to some direct dyes.
[0004] In recent years additional methods have been devised for treating cellulosic fiber-containing
products in order to impart durable crease retention, wrinkle resistance and smooth
drying characteristics to these products. As discussed, formaldehyde has been crosslinked
with cellulose materials to produce these products. It is also known to treat cellulose
materials with resins or precondensates of the urea-formaldehyde or substituted urea-formaldehyde
type to produce a resin treated durable press product. As noted in
U.S. patent Number 3,841,832, while formaldehyde has made a significant contribution to the cotton finishing art,
the result has been far from perfect. For instance, in some cases the formaldehyde
crosslinking treatment has tended to lack reproducibility, since control of the formaldehyde
cross-linking reaction has been difficult. As noted in United States patent
4, 396,390, lack of reproducibility is especially true on a commercial scale.
[0005] Moreover, unacceptable loss of fabric strength has also been observed in many of
the proposed aqueous formaldehyde treatment processes. When high curing temperatures
were used with an acid or potential acid catalyst, excess reaction and degradation
of the cotton often happened which considerably impaired its strength. On the other
hand, when attempts were made to achieve reproducibility at temperatures of 41,11°C
(106°F) or less, much longer reaction or finishing times were usually required, rendering
the process economically relatively unattractive. A solution to this is set forth
in United States Patent
4,108,598, the entire disclosure of which is herein incorporated by reference.
[0006] US 3,663,974 discloses a fabric comprising cellulose treated with aldehyde and optionally further
agents, and as softeness.
[0007] US 3,420,696 discloses a process of treating cellulose with aldehyde and a carbonate.
[0008] GB 1,097,336 discloses a process for providing carpets with anti-soiling properties.
[0009] US 2,243,765 discloses the treatment of cellulose with formaldehyde.
[0010] US 3,812,201 discloses the application of a carboxy functional siloxane to textiles.
[0011] EP 0 360 248 A2 discloses a formaldehyde free process for treating textile fabrics.
SUMMARY OF THE INVENTION
[0012] In accordance with the present invention it is possible to obtain good durable press
properties in a cellulosic fiber-containing fabric with good strength retention with
a process that produces consistent results. This invention relates to a durable press/wrinkle-free
process for cellulosic fiber containing fabrics and more particularly to a process
which utilizes formaldehyde and catalysts with silicone elastomers to impart wrinkle
resistance to the cellulosic fiber-containing fabrics while reducing loss in both
tensile and tear strength. This process is particularly effective on 100% cotton fabric.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0013] Such cellulosic fiber-containing fabrics include cloth made of cotton or cotton blends.
There is a constant consumer demand for better treatment, that is, a more wrinkle-free
product and for higher amounts of cotton in the blended fabric, or preferably, a 100%
cotton fabric. There is a great demand for a wrinkle-free fabric made entirely of
cotton and having good tensile and tear strength. This has been achieved and 100%
cotton fabrics are treated today, but only in heavier weight pants or bottom weight
fabrics. Unfortunately, the more wrinkle-free the cellulosic containing fabric is
made by treatment in a formaldehyde system, the greater the loss in tear and tensile
strength.
[0014] That is, as the amount of chemicals used in the treating process are increased to
obtain an acceptable wrinkle resistance in the treated fabric, the loss in tear and
tensile strength fall to unacceptable levels. Polyester fibers are most often blended
into the cotton to form a polyester cotton blend fabric to compensate for the loss
in strength of the treated cotton. Polyester in amounts of up to 65% are commonly
used. Because of the presence of polyester fibers or other synthetic fibers in the
blend, these blended fabrics are sufficiently strong but do not have the comfort or
feel of fabrics containing a higher amount of cotton, or most desirably, 100% cotton.
The process of the present invention overcomes the disadvantages of the prior art
processes and permits the presence of higher percentages of cotton in the blend and
even the treatment of lighter weight or shirting weight 100% cotton fabrics to a commercially
acceptable wrinkle free standard while retaining adequate strength in the fabric to
also make it commercially acceptable. Commercial acceptability of the treated fabric
is the ultimate goal of the process.
[0015] The durable press process of the present invention for treating cotton containing
fabrics and 100% cotton fabric, comprises treating a cellulosic fiber-containing fabric
with aqueous formaldehyde and a catalyst capable of catalyzing the crosslinking reaction
between formaldehyde and cellulose in the presence of a silicone elastomer, heat curing
the treated cellulosic fiber-containing fabric, preferably having a moisture content
of more than 20% by weight, under conditions at which formaldehyde reacts with the
cellulose in the presence of a catalyst and without the substantial loss of formaldehyde
before the reaction of formaldehyde with cellulose to improve the wrinkle resistance
of the fabric while reducing the loss in both tensile and tear strength. It is preferable
that the cellulose containing fabric is in the fully swollen state.
[0016] Any silicone eslastomer may be used in the present invention. Silicone elastomers
are known materials. Silicone elastomers have a backbone made of silicon and oxygen
with organic substituents attached to silicon atoms comprising n repeating units of
the general formula:
[0017] The groups R and R
1 may be the same or different and includes for example, lower alkyl, such as methyl,
ethyl, propyl, phenyl or any of these groups substituted by hydroxy groups, fluoride
atoms or amino groups; in other words, reactive groups to cellulose.
[0018] The silicones used to make the silicone elastomers in the present .invention are
made by conventional processes which may include the condensation of hydroxy organosilicon
compounds formed by hydrolysis of organosilicon halides. The required halide can be
prepared by a direct reaction between a silicon halide and a Grignard reagent . Alternate
methods may be based on the reaction of a silane with unsatutrated compounds such
as ethylene or acetylene. After separation of the reaction products by distillation,
organosilicon halides may be polymerized by carefully controlled hydrolysis to provide
the silicone polymers useful in the present invention.
[0019] For example, elastomers may be made by polymerization of the purified tertramer using
alkaline catalysts at 100 to 150°C (212-302 degrees F), the molecular weight being
controled by using a monofuncfional silane. Curing characteristics and properties
may be varied over a wide range by replacing some methyl groups by -H, -OH, fluoroalkly,
alkoxy or vinyl groups and by compounding with flllers as would be appreciated by
one of ordinary skill in the art.
[0020] Silicone elastomers used in the present invention are high weight materials, generally
composed of dimethyl silicone units (monomers) linked together in a linear chain.
These materials usually contain a peroxide type catalyst which causes a linking between
adjacent methyl groups in the form of methylene bridges. The presence of crosslinking
greatly improves the durability of the silicone elastomer on cellulose by producing
larger molecules.
[0021] It is also possible to produce a reactive silicone elastomer, which is one where
reactive groups capable of reacting with the substrate have been added to the linear
dimethyl silicone polymer. These silicones are capable of reacting both with cellulose
substrates as well as with most protein fibers, and are characterized by much greater
durability of the silicone polymer on the substrate, even approaching the life of
the substrate.
[0022] Therefore silicone elastomers which give off reaction gases or chemicals indicating
chemical reaction with the substrate are much preferred over non reactive silicone
elastomer, but this is not to say that non reactive silicone elastomers cannot be
used in the process. Different elastomers, by different manufacturers have all shown
increases in tensile as well as tear strength, as shown in Tables I and II included
herein. Elastomeric silicone polymers have been found to increase strength whereas
simple emulsified silicone oils (or lubricants) do not give increases in tensile strength.
[0023] The aqueous system containing formaldehyde, an acid catalyst, silicone elastomer
and a wetting agent may be padded on the fabric to be treated, preferably to insure
a moisture content of more than 20% by weight on the fabric, and then the fabric cured.
The padding technique is conventional to the art and generally comprises running the
fabric through the aqueous solution which is then passed through squeezing rollers
to provide a wet pick-up of about 66%. As is conventional in the art, the concentration
of the reactants in the aqueous solution are adjusted to provide the desired amount
of reactants on the weight of the fabric (OWF).
[0024] It is possible to use unexpected high temperatures which allow the crosslinking reaction
to take place before the loss of formaldehyde is great enough to affect the process
and provide inadequate treatment. In accordance with this aspect of the invention,
the padded fabric may be immediately plunged into a heating chamber at about 148,88°C
to about 162,77°C (about 300 to about 325°F). This is an important commercial aspect
of the invention as it enables continuous processing on a commercial scale at speeds
of 91,5 to 183 m (100-200 yards) per minute. It must be appreciated, that this process
is designed for commercial applications which are demanding in that the process must
be commercially viable.
[0025] This may also be accomplished by curing at a low temperature with an active catalyst.
It is also possible to use any combination of techniques which prevent the substantial
loss of formaldehyde during the curing. For example, a low temperature may be used
in combination with an aqueous formaldehyde solution. It would also be possible to
use a pressurized system wherein the pressure is greater than atmospheric, thereby
preventing the substantial loss of formaldehyde before the formaldehyde crosslinks
with the cellulosic fiber-containing fabric being treated.
[0026] In addition the process of the present invention uses less formaldehyde than other
known processes. Shirting fabrics treated in accordance with the process of the present
invention contain approximately 1000 ppm after treatment before steaming on a shirting
fabric as compared to 3000 ppm+ by another crosslinking process on a similar shirting
fabric. Tests have shown that continuously running steaming chambers to which the
treated fabric is exposed should effectively remove residual formaldehyde to concentrations
as low as 200 ppm. This is also an important aspect of the present invention in view
of consumers concern about the presence of formaldehyde in their purchased garments.
It is also possible to wash fabrics either continuously or in batch washers. Both
approaches remove essentially all of the formaldehyde.
[0027] It is known to add to the fabric a polymeric resinous additive that is capable of
forming soft film. For example, such additives may be a latex or fine aqueous dispersion
of polyethylene, various alkyl acrylate polymers, acrytonitrile-butadiene copolymers,
deacetylated ethylene-vinyl acetate copolymers, polyurethanes and the like. Such additives
are well known to the art and are generally commercially available in concentrated
aqueous latex form. Such a latex is diluted to provide about 1 to 3% polymer solids
in the aqueous catalyst-containing padding bath before the fabric is treated therewith.
One known softener which was virtually the softener of choice in the durable press
process using resin treatment or formaldehyde crosslinking was high density polyethylene,
Mykon HD. It has been unexpectedly discovered that the substitution of a silicone
elastomer for high density polyethylene significantly reduces the loss in tear strength
of the treated fabric after washing as well as providing better control of the process
as may be seen from the examples. The importance of good control of the process is
essential to a commercially viable process to provide a consistent product from run
to run which is not adversely affected by variations in atmospheric pressure, humidity
and the like.
[0028] As the cellulosic fiber-containing fabric which may be treated by the present process
there can be employed various natural cellulosic fibers and mixtures thereof, such
as cotton and jute, Other fibers which may be used in blends with one or more of the
above-mentioned cellulosic fibers are, for example, polyamides (e.g., nylons), polyesters,
acrylics (e.g., polyacrylonitrile), polyolefins, polyvinyl chloride, and polyvinylidene
chloride. Such blends preferably include at least 35 to 40% by weight, and most preferably
at least 50 to 60% by weight, of cotton or natural cellulose fibers.
[0029] The fabric may be a resinated material but preferably it is unresinated; it may be
knit, woven, non-woven, or otherwise constructed. After processing, the formed wrinkle
resistant fabric will maintain the desired configuration substantially for the life
of the fabric. In addition, the fabric will have an excellent wash appearance even
after repeated washings.
[0030] This invention is not dependent upon the limited amounts of moisture to control the
crosslinking reaction since the crosslinking reaction is most efficient in the most
highly swollen state of the cellulose fiber. Lesser amounts of moisture may be used
but are less preferred.
[0031] However, the silicone elastomer must be present in a sufficient amount to reduce
the loss of tensile and tear strength in the fabric normally associated with the treatment
of the same fabric in a prior art treatment process which may include the use of softeners
such as Mykon HD. The formulation and process of the present invention may be adjusted
to meet specific commercial requirements for the treated fabric. For example, formaldehyde
and the catalyst concentration may be increased to provide better treatment; then
the concentration of the softener is also increased to combat the loss of tear strength
caused by the increased amount of catalyst used in the process. This lends itself
to computerized control of the systems for treating various fabrics and allows variation
in the treatment of different fabrics, which is another advantage of the process of
the present invention.
[0032] While silicone oils are known as silicone softeners and have found some use in fabric
treatment, they suffer serious disadvantages in having a strong tendency to produce
non-removable spots. However, the particular silicone elastomer used in the process
of the present invention completely overcomes these problems.
[0033] Blended fabrics to be treated in accordance with the present invention are immersed
in a solution to provide a pick up or on the weight of fabric (OWF) of about 3 % formaldehyde,
1 % of catalyst, 1% of the silicone elastomer. This requires a pickup of about 66%
by weight of the aqueous formulation to achieve the above stated percentage of reactants
on the fabric. However, when treating 100% cotton fabric chemical concentrations must
be increased so that 5% formaldehyde OWF, about 2% catalyst and about 2% elastomer
padded onto the fabric. This is contrary to the prior art attempts to treat 100% cotton
where the concentration of reactants were decreased because of the loss of strength
due to the treatment process. The curing temperature may be about 148,88°C (about
300°F). In fact, the padded fabric may be plunged into a oven or heating chamber at
148,88°C (300°F).
[0034] The formaldehyde concentration may be varied as would be appreciated by one of ordinary
skill in the art. The process inlcudes the use of formaldehyde in the form of an aqueous
solution having a concentration of 0.5% to 10%, by weight. The preferred formaldehyde
concentration on the fabric is from 1.5% to 7% based on the weight of the fabric.
[0035] The catalyst used in the process includes fluorosilicic acid for mild reactions and
is applicable to blend fabrics. On heavyweight, all-cotton fabrics, or shirting fabrics,
a catalyst such as magnesium chloride spiked with citric acid can be used, which is
a commercially available catalyst Freecat No. 9, as is a similar catalyst which contains
aluminum/magnesium chloride. During the crosslinking reaction at the curing stage,
moisture is given up from the fabric as the crosslinking occurs, resulting in a decrease
in the moisture content of the fabric. In fabrics having a moisture content of 20%
or less, this tends to lower the effectiveness of the crosslinking reaction requiring
higher concentrations of formaldehyde, in a preferred aspect of the present invention,
moisture is given up from a high level, that is, greater than 20%, preferably greater
than 30%, e.g., from 60-100% or more, and the crosslinking is optimized. Moisture,
which is so difficult to control, is not a problem in the present invention. Of course,
water is not allowed to be present in so much of an excess as to cause the catalyst
to migrate on the fabric.
[0036] All results reported in the following examples were obtained by the following standard
methods:
- 1. Appearance of Fabrics after Repeated Home Launderings:
AATCC Test Method 124-1992
- 2. Tensile Strength: ASTM :Test Method D-1682-64 (Test 1C)
- 3. Tear Strength: ASTM : Test Method D-1424-83 Falling Pendulum Method
- 4. Shrinkage: AATCC Test Method 150-1995
- 5. Wrinkle Recovery of Fabrics: Recovery Angle Method:
AATCC Test Method 66-1990 which provides the DP value.
[0037] In determining the DP value for the fabrics, a visual comparative test is performed
under controlled lighting conditions in which the amount of wrinkles in the treated
fabric is compared with the amount of wrinkles present on pre-wrinkled plastic replicas.
The plastic replicas have various degrees of wrinkles and range from a value of 1
DP for a very wrinkled fabric to 5.0 DP for a flat wrinkle free fabric. The higher
the DP value, the better. For a commercially acceptable wrinkle free fabric, a DP
value of 3.5 is desired but rarely achieved. As would be appreciated by one of ordinary
skill in the art, the difference between a DP of 3.50 and 3.25 is significant. At
DP 3.50 all .wrinkles are rounded and disappearing. At DP 3.25 all wrinkles are still
visible and show sharp creases. The goal for commercial acceptance is a DP of 3.50
with a filling tensile strength 25 pounds and a filling tear strength of 24 ounces.
Of equal or even greater importance to these properties is that the process must be
consistently reproducible on an industrial scale.
[0038] In all of the following examples a non-ionic wetting agent was used as is conventional
to the art. The wetting agent was used in an amount of about 0.1% by weight. The wetting
agent used in all of the examples was an alkyl aryl polyether alcohol such as Triton
X-100. The wetting agent is used to cause complete wetting by the aqueous treating
solution of the fibers in the fabric.
[0039] All of the samples were run on all-cotton fabrics which are the most difficult to
treat because of the severe loss in tensile and tear strength, which causes the treated
fabric to be commercially unacceptable. The normal industry standard for tear and
tensile strength for an all cotton shirting fabric is characterized by having a filling
tensile strength of 11,35 kg (25 pounds) and a filling tear strength of 680,376 g
(24 ounces). The cotton fabric must meet and/or exceed this standard. The test conditions
are set forth in the table.
[0040] The silicone elastomer was the commercially available softener Sedgefield Elastomer
Softener ELS, which is added as an opaque white liquid which contains from 24-26%
silicone, has a pH of from 5.0-7.0 and is readily dilutable with water. When used
in the present invention, this product produced DP values at catalyst concentrations
of 0.8%, whereas with the Mykon HD, a catalyst concentration of 2.0% was required
to give a DP value of 3.50 after 1 washing and 3.25 after 5 washings.
[0041] The tensile strength with a catalyst concentration of 0.8% and tear strength are
significantly and unexpectedly higher than the 2.0% catalyst required with Mykon HD
to give equal DP results. Catalyst concentration of 1.0% ELS is recommended to ensure
a margin of safety, such that any variation in treatment will be well within accepted
specifications.
[0042] The following examples are being presented not as limitations but to illustrate and
provide a better understanding of the invention. In order to confirm the fact that
formaldehyde was being lost from the conventional processes, experiments were conducted
in which the fabric was heated very quickly by very hot air as in the conventional
processes as well as in accordance with the present invention.
Example 1
[0043] As indicated, it is possible to cure with a high enough temperature that the crosslinking
reaction is achieved before sufficient formaldehyde is lost preventing good treatment.
In this experiment, 100% cotton oxford shirting was padded with formaldehyde (37%)
at a concentration of 5.0% OWF, 0.8 % OWF of Freecat #9 Accelerator manufactured by
Freedom Textile Chemicals Co. and 1.5 % OWF of a silicone elastomeric softener, Sedgesoft
ELS manufactured by Sedgefield Specialties, to a pickup of approximately 60-70%. The
sample was then dried and cured while under tension in an air circulating oven set
at 148,88°C (300°F) for 10 minutes.
Example 2
[0044] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 1.0% OWF. Otherwise
the sample was treated precisely the same.
Example 3
[0045] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 2.0% OWF. Otherwise
the sample was treated precisely the same.
Example 4
[0046] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 0.4°C OWF, and Mykon
HD was substituted for the Sedgesoft ELS elastomeric Softener. Otherwise the sample
was treated precisely the same.
Example 5
[0047] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 0.8% OWF, and Mykon
HD was substituted for the Sedgesoft ELS elastomeric Softener. Otherwise the sample
was treated precisely the same.
Example 6
[0048] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 1.0% OWF, and Mykon
HD was substituted for the Sedgesoft ELS elastomeric Softener Otherwise the sample
was treated precisely the same.
Example 7
[0049] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 1.5% OWF, and Mykon
HD was substituted for the Sedgesoft ELS elastomeric Softener. Otherwise the sample
was treated precisely the same.
Example 8
[0050] Another sample of the same fabric as used in Example 1 was padded with a similar
solution differing only in that the catalyst Accelerator #9 was 2.0% OWF, and Mykon
HD was substituted for the Sedgesoft ELS elastomeric Softener Otherwise the sample
was treated precisely the same.
Example 9
[0051] A sample of the same fabric was washed in a home washer and tumble tried, but not
treated with any crosslinking process.
Example 10
[0052] Another sample of the same fabric served as an untreated, unwashed control.
[0053] It is clear in Table No. I that samples treated with the elastomeric softener produced
higher degrees of durable press than any of the samples treated with Mykon HD. Tensile
Strengths are similar as is shrinkage for each degree of treatment.
[0054] In another experiment, the results shown in Table No. II, samples of 100% cotton
oxford shirting were padded with two concentrations of formaldehyde 3.0 and 5.0% OWF,
each concentration also treated with three concentrations of Accelerator #9 Catalyst,
0.8, 1.0, and 2.0%. In one half of the samples, Sedgesoft ELS was applied and in the
other half Mykon HD was used as the softener. Both softeners were applied at 1.5%
OWF. Each of the samples were padded with the respective solutions shown in Table
No. II, then cured at 148,88 (300°F) for 10 minutes under tension. All samples were
treated in precisely the same way, intervals were timed.
[0055] It is clearly seen in Table II (Example 11 to Example 22 and the control) that after
5 washes, the Sedgesoft ELS samples have almost twice the tear strength of the Mykon
HD samples without exception. In addition, again seen, the DP values are higher indicating
better smoothness.
1. A durable press process for cellulosic fiber-containing fabrics comprising treating
a cellulose fiber-containing fabric with formaldehyde, a catalyst capable of catalyzing
the crosslinking reaction between formaldehyde and cellulose, and an effective amount
of silicone elastomer, heat curing said treated cellulosic fiber-containing fabric
under conditions at which formaldehyde reacts with cellulose in the presence of the
catalyst and silicone elastomer, without a substantial loss of formaldehyde before
the reaction of the formaldehyde with the cellulose to improve the wrinkle resistance
of the fabric while reducing loss in tensile and tear strength.
2. The process of claim 1 wherein the heat curing is at a temperature which prevents
the substantial loss of formaldehyde during curing.
3. The process of claim 1 wherein the heat curing step is carried out at a high enough
temperature to allow the crosslinking step to occur before sufficient formaldehyde
leaves the fabric and affects the process.
4. The process of claim 1 wherein the fabric being cured has a moisture content of more
than 20% by weight.
5. The process of claim 2 wherein the heat curing is carried out at a temperature of
from (100°F to 350°F) 37.77°C to 176.66°C.
6. The process in claim 2 where the heat curing is carried out in the preferred range
of (250 to 325°F) 121.11°C to 162.77°C.
7. The process of claim 1 wherein said fabric is heat cured by gradually increasing the
temperature.
8. The process of claim 5 wherein the heat curing is carried out at a temperature of
from (100°F to 300°F) 37.77°C to 148.88°C.
9. The process in claim 1 where the formaldehyde is in the form of an aqueous solution
of formaldehyde having a concentration of 0.5% to 10%.
10. The process in claim 1 where the preferred formaldehyde concentration range is from
1.5% to 7% on the weight of the fabric.
11. The process of claim 1, wherein the fabric is 100% cotton shirting.
1. Permanent-Press-Ausrüstungs-Verfahren für cellulosefaserhaltige Gewebe, umfassend
das Behandeln eines cellulosefaserhaltigen Gewebes mit Formaldehyd, einem Katalysator,
der die Vernetzungsreaktion zwischen Formaldehyd und Cellulose katalysieren kann,
und einer wirksamen Menge eines Siliconelastomers, das Warmhärten des behandelten
cellulosefaserhaltigen Gewebes unter Bedingungen, bei denen Formaldehyd in Gegenwart
des Katalysators und Siliconelastomers mit Cellulose reagiert, ohne einen wesentlichen
Verlust von Formaldehyd vor der Reaktion des Formaldehyds mit der Cellulose, um die
Knitterfestigkeit des Gewebes zu verbessern, während die Abnahme der Zug- und Reißfestigkeit
verringert wird.
2. Verfahren nach Anspruch 1, wobei das Warmhärten bei einer Temperatur erfolgt, welche
einen wesentlichen Verlust von Formaldehyd während des Härtens verhindert.
3. Verfahren nach Anspruch 1, wobei der Warmhärtungsschritt bei einer Temperatur durchgeführt
wird, die hoch genug ist, um den Vernetzungsschritt stattfinden zu lassen, bevor ausreichend
Formaldehyd das Gewebe verlässt und das Verfahren beeinträchtigt.
4. Verfahren nach Anspruch 1, wobei das Gewebe, das gehärtet wird, einen Feuchtigkeitsgehalt
von mehr als 20 Gew.-% aufweist.
5. Verfahren nach Anspruch 2, wobei das Warmhärten bei einer Temperatur von 37,77 °C
bis 176,66 °C (100°F bis 350 °F) durchgeführt wird.
6. Verfahren nach Anspruch 2, wobei das Warmhärten in dem bevorzugten Bereich von 121,11
°C bis 162,77 °C (250 bis 325 °F) durchgeführt wird.
7. Verfahren nach Anspruch 1, wobei das Gewebe durch allmähliches Erhöhen der Temperatur
warmgehärtet wird.
8. Verfahren nach Anspruch 5, wobei das Warmhärten bei einer Temperatur von 37,77 °C
bis 148,88 °C (100°F bis 300 °F) durchgeführt wird.
9. Verfahren nach Anspruch 1, wobei der Formaldehyd in Form einer wässrigen Lösung von
Formaldehyd mit einer Konzentration von 0,5 % bis 10 % vorliegt.
10. Verfahren nach Anspruch 1, wobei der bevorzugte Bereich der Formaldehydkonzentration
1,5 % bis 7 %, bezogen auf das Gewicht des Gewebes, beträgt.
11. Verfahren nach Anspruch 1, wobei es sich bei dem Gewebe um einen Hemdenstoff aus 100
% Baumwolle handelt.
1. Procédé pour conférer une résistance durable au froissement à des tissus contenant
des fibres cellulosiques, comprenant le traitement d'un tissu contenant des fibres
cellulosiques par du formaldéhyde, un catalyseur apte à catalyser la réaction de réticulation
entre le formaldéhyde et la cellulose, et une quantité efficace d'élastomère de silicone,
le durcissement à chaud dudit tissu traité contenant des fibres cellulosiques dans
des conditions dans lesquelles le formaldéhyde réagit avec la cellulose en présence
du catalyseur et de l'élastomère de silicone, sans perte substantielle de formaldéhyde
avant la réaction du formaldéhyde avec la cellulose, afin d'améliorer la résistance
au froissement du tissu tout en réduisant la perte de résistance à la traction et
à la déchirure.
2. Procédé selon la revendication 1, dans lequel le durcissement à chaud est effectué
à une température qui empêche la perte substantielle de formaldéhyde pendant le durcissement.
3. Procédé selon la revendication 1, dans lequel l'étape de durcissement à chaud est
effectuée à une température suffisamment élevée pour permettre le déroulement de l'étape
de réticulation avant qu'une quantité suffisante de formaldéhyde quitte le tissu et
affecte le procédé.
4. Procédé selon la revendication 1, dans lequel le tissu en cours de durcissement a
une teneur en humidité supérieure à 20 % en poids.
5. Procédé selon la revendication 2, dans lequel le durcissement à chaud est réalisé
à une température de 37,77 °C à 176,66 °C (100 °F à 350 °F).
6. Procédé selon la revendication 2, dans lequel le durcissement à chaud est effectué
dans la plage préférée de 121,11 °C à 162,77 °C (250 °F à 325 °F).
7. Procédé selon la revendication 1, dans lequel ledit tissu est durci à chaud en augmentant
graduellement la température.
8. Procédé selon la revendication 5, dans lequel le durcissement à chaud est réalisé
à une température de 37,77 °C à 148,88 °C (100 °F à 300 °F).
9. Procédé selon la revendication 1, dans lequel le formaldéhyde se présente sous la
forme d'une solution aqueuse de formaldéhyde, ayant une concentration de 0,5 % à 10
%.
10. Procédé selon la revendication 1, dans lequel la plage préférée de la concentration
de formaldéhyde est de 1,5 % à 7 % du poids du tissu.
11. Procédé selon la revendication 1, dans lequel le tissu est une toile pour chemises
100 % coton.