Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation improves elasticity – bendability,...
Reexamination Certificate
1999-03-16
2003-03-04
Diamond, Alan (Department: 1753)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation improves elasticity, bendability,...
C442S105000, C442S106000, C442S107000, C442S414000, C442S327000, C442S369000, C442S333000, C442S152000, C442S153000, C008S116400, C008S115600, C008S115700, C008S116100
Reexamination Certificate
active
06528438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
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.
2. Description of Related Art
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.
It has long been known to treat cellulosic materials with formaldehyde, as is evidenced by U.S. Pat. No. 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 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.
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. Pat. No. 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 U.S. Pat. No. 4,396,390, lack of reproducibility is especially true on a commercial scale.
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 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 U.S. Pat. No. 4,108,598, the entire disclosure of which is herein incorporated by reference.
SUMMARY OF THE INVENTION
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
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.
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.
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.
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:
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.
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 me
Diamond Alan
Dinsmore & Shohl LLP
The Procter & Gamble & Company
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