Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Cellulose fibers
Reexamination Certificate
2002-01-18
2004-09-21
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Cellulose fibers
C008S116100, C008S181000, C536S056000
Reexamination Certificate
active
06793686
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a finishing process for cellulosic textiles which provides a textile having a desirable combination of inherent durable press properties, improved moisture content and improved wicking properties.
BACKGROUND OF THE INVENTION
Chemical treatments are typically applied to cellulosic textiles in an effort to impart a number of desirable properties. Durable press properties include wrinkle resistance, permanent creases, shrinkage resistance, smooth drying properties. Other desirable properties include improved fiber integrity resulting in less fabric pilling. Such chemical treatments, or finishing processes are applied to yarns, fabrics, or entire garments made of cotton, rayon, linen, ramie, regenerated wood cellulose, or blends made therefrom with polyester.
One such finishing process consists of applying and reacting a crosslinking agent on the yarn, fabric or garment of interest. These finishing agents, or crosslinking agents, are generally bifunctional compounds that, in the context of cellulose crosslinking, covalently couple a hydroxy group of one cellulose to another hydroxy group on a neighboring cellulose fiber. These types of crosslinked cellulose fibers and various methods of preparation are known. See, for example, Tersoro and Willard, Cellulose and Cellulose Derivatives, Bikales and Segal, eds., Part V, Wiley-Interscience, New York, (1971), pp. 835-875.
The traditional chemical crosslinking process has certain disadvantages. For example, formaldehyde, the least expensive and most effective cross-linking agent for cellulosic textiles, is an irritant and a mutagen in certain bacterial and animal species and is officially classified as a probable human carcinogen. Fabrics treated with formaldehyde or formaldehyde-derived crosslinking agents undesirably tend to release formaldehyde over time. Other types of crosslinking agents have proved unsatisfactory for a number of reasons and often do not provide a satisfactory degree of finishing properties.
In addition, certain conditions under which traditional chemical crosslinking must be conducted are harsh, and counteract some of the desirable effects of the crosslinking treatment. For example, these conditions can reduce the overall integrity of the fibers in treated textiles sometimes resulting in poor mechanical properties such as tear strength. In addition, the ability of the fiber/textile to absorb moisture is decreased. This decreased absorptivity is manifested in a decreased ability to of the textile to absorb and retain dyes.
There are further disadvantages to the manufacturing use of chemical crosslinking finishing treatments. Salts and excess residual chemicals formed during the crosslinking reaction, such as formaldehyde, must be washed out of the textile. Therefore, in addition to environmental problems caused by contaminated wastewater, the chemical crosslinking process ordinarily requires further expensive post-treatment processes in order to ensure that the treated textile is free of dangerous chemicals and irritants.
Accordingly, there is a continuing need to provide a finishing process for cellulosic textiles which provides textiles having a combination of desirable properties and which does not require the use of expensive and hazardous chemical crosslinking agents.
SUMMARY OF THE INVENTION
The present invention provides a finishing process for cellulosic textiles which does not require the use of expensive and hazardous chemical crosslinking agents.
According to the finishing process of the present invention, cellulosic textiles are modified via a nitroxide-mediated oxidation method which imparts controlled quantities of aldehyde and carboxyl functionality to the textile.
Surprisingly, the modified cellulosic textiles finished according to this invention demonstrate a number of desirable properties including a combination of inherent durable press properties and improved moisture content, and wicking properties.
DETAILED DESCRIPTION OF THE INVENTION
According to the finishing process of the present invention, cellulosic textiles are modified via a nitroxide-mediated oxidation method which imparts controlled quantities of aldehyde and carboxyl functionality to the textile. In particular, the primary (“C6”) alcohols on the cellulose portion of cellulosic textiles, are selectively oxidized with a suitable oxidant in the presence of a nitroxide radical mediator.
The finishing process of the present invention is related to the nitroxide-mediated processes described in U.S. Pat. No. 6,228,126 and pending U.S. Ser. Nos. 09/454,400, 09/575,303, the disclosures of which are incorporated herein by reference. The finishing process can be conducted in a single-phase aqueous or non-aqueous medium or in a bi-phase medium, in particular in an aqueous medium. The reaction temperature is typically 0 to 50° C. In aqueous media, the absolute amount of aldehyde formed from primary alcohols and the ratio of aldehyde formed to carboxylic acid formed in the oxidation reaction can be controlled by manipulating the reaction conditions including oxidant amounts, reagent and catalyst concentrations, time, temperature, etc.
The reaction conditions and co-catalysts used may be manipulated by one skilled in the art to achieve the desired end product. The modified cellulosic textiles of this invention can be prepared by a method which involves the selective oxidation of cellulosic textile using a limited amount of oxidant and mediated with a nitroxyl radicalunder defined conditions to provide derivatives with effective aldehyde and carboxyl content.
The nitroxyl radical mediator used herein is a di-tertiary alkyl nitroxyl radical having one of the following formulas:
in which A represents a chain (saturated or unsaturated) of particularly two or three atoms, in particular carbon atoms or a combination of one or two carbon atoms with an oxygen or nitrogen atom, and the R
1
-R
6
groups represent the same or different alkyl groups. Chain A may be substituted by one or more groups such as alkyl, alkoxy, aryl, aryloxy, acyloxy, amino, amido or oxo groups, or by a divalent group or multivalent group which is bound to one or more other groups having formula I. Particularly useful nitroxyl radicals are di-tertiary alkyl nitroxyl radicals having the formula:
in which Y is either H, OH, OR′, NH—C(O)—R′, OC(O)R′, keto or acetal derivatives, and R′ is alkyl or aryl; and each of the R
1
-R
4
groups represent the same or different alkyl groups of 1 to 18 carbon atom and more particularly methyl groups. Nitroxyl radicals of this type include those in which a) the R
1
-R
4
groups are all methyl (or alkyl of 1 carbon atom) and Y is H, i.e., 2,2,6,6-tetramethyl-1-piperdinyloxy (TEMPO); b) R
1
-R
4
groups are methyl and Y is OH and identified as 4-hydroxy TEMPO; and c) R
1
-R
4
groups are methyl and Y is NH—C(O)—CH
3
and identified as 4-acetamido TEMPO. In particular, the nitroxyl radical is TEMPO or 4-acetamido TEMPO. The nitroxyl radical is used in an effective amount to mediate the oxidation, particularly in an amount of from about 0.001 to 20% by weight, more particularly from about 0.001 to 0.2% by weight, even more particularly from about 0.005 to 0.02% by weight, based on the weight of cellulose contained in the cellulosic textile. The nitroxyl radical can be added to the reaction mixture or generated in situ from the corresponding hydroxylamine or oxoammonium ion.
The oxidant used in this invention can be any material capable of converting nitroxyl radicals to their corresponding oxoammonium salt. Particularly useful oxidants are the alkali or alkaline-earth metal hypohalite salts such as sodium hypochlorite, lithium hypochlorite, potassium hypochlorite or calcium hypochlorite. An alkali or alkaline earth-metal hypobromite salt may also be used and it may be added in the form of the hypobromite salt itself, such as sodium hypobromite, or it may be formed in situ from the addition of a suitable oxidant such as sodium hypochlorite and an alkali or alkaline-earth metal br
Cimecioglu A. Levent
Rodrigues Klein A.
Duncan Laurelee A.
Einsmann Margaret
LeCroy David P.
National Starch and Chemical Investment Holding Corporation
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