Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Cellulose fibers
Reexamination Certificate
2000-06-09
2002-01-08
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Cellulose fibers
C008S116100, C008S127100
Reexamination Certificate
active
06336943
ABSTRACT:
FIELD OF THE INVENTION
In general, the present invention is directed to a process for improving cotton fibers and textile products containing cotton fibers by, for example, making them resistant to cross-staining. In particular, the present invention is directed to an anionic treatment process for cotton fibers that makes the fibers repel anionically-charged dyes and auxiliaries or attract cationically charged dyes and auxiliaries.
BACKGROUND OF THE INVENTION
The problem of cross-staining between cotton fabrics during laundering and processing is a significant household and textile problem. Cross-staining relates to the transferring of dye that may occur between fabrics under either wet or dry conditions while fabrics are being manufactured, processed or laundered. Television commercials are aired daily for expensive detergents meant to minimize cross-staining. In fact, much advertising and product manufacturing are devoted to this common annoyance. The detergents that advertise colorfastness are designed to approach the problem of cross-staining through the use of dye antiredeposition agents that are incorporated into their formulas. These antiredeposition agents, however, add expense to the detergents and are not fully effective in preventing cross-staining. Thus, a method of preventing dye transfer without relying on the use of detergents would prove to be both practical and economical.
The dye transfer between cellulosic fabrics, such as cotton fabrics, occurs when fabrics are laundered or processed in the same bath. Dye transfer occurs because cellulosic fibers have a mild attraction for anionic classes of dyes, which are the majority of the dyes now employed to dye cotton and other cellulosic fabrics and blends. Dyes are made to be anionic or negatively charged so that they will benefit from water solubility. Such classes of dyes include reactives, directs, acids, and the like. A primary example of this dye transfer is the staining of the white pockets in blue jeans during garment manufacture and during laundering. The anionic leuco form of the indigo dyes in the blue jeans are absorbed by the undyed cotton fibers in the pockets because of their chemical attraction to one another.
An even more well-known example is the transfer of dyes between dark-colored garments and white or light-colored garments during the laundering process. The loosely-held anionic dyes in the fibers of the dark-colored garments stain the white or light-colored garments. This dye transfer may adversely affect white or light-colored garments. Similarly, striped or patterned garments containing both dark-colored fabric and white or light-colored fabric may experience bleeding of the dark-colored dyes on to the lighter portions because of the attraction of unfixed anionic dyes to the cellulosic fibers in the white or light-colored portions. Therefore, it is evident that weakening this attraction between the anionic dyes and the cotton fibers would provide a solution to the problem of dye transfer.
A need currently exists for a solution to the problem of dye transfer regarding cellulosic fabrics so that the needs for expensive detergents and other methods of colorfastness are eliminated. In particular, a need exists for a process that treats cellulosic fibers in order to permanently increase their anionic character so that these fibers are able to resist anionic dyes that cross stain fabrics. The present invention is directed to a process that meets the above described need.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses the foregoing disadvantages and drawbacks of prior art constructions. Accordingly, it is an object of the present invention to provide a process for making cellulosic fibers, such as cotton fibers, and textile products made from the fibers anionic, resistant to cross-staining, and improved as far as hand, appearance, and comfort.
Another object of the present invention is to provide a process for making cotton fibers resistant to cross-staining through a permanent anionic treatment.
Another object of the present invention is to provide a process that not only makes cotton fibers resistant to cross-staining, but also provides the fibers with a greater attraction to cationic fabric softeners and bacteriocides.
It is another object of the present invention to provide a process for treating cotton fibers with a softener that results in a fabric having great softness properties, good durability, and in which the softener is wash resistant.
Another object of the present invention is to provide a process for treating cotton fibers in a manner that permits the fibers to become bonded with bacteriocides at high and effective concentration levels.
Still another object of the present invention is to provide a process for treating cotton fibers or textiles containing cotton fibers with a sulfamate, which increases the anionic charge of the material.
Another object of the present invention is to treat cotton fibers, or textiles made from the fibers, with a pre-formed complex containing sulfamic acid and urea such that a material resistant to cross-staining can be formed at lower temperatures.
It is another object of the present invention to treat cotton fibers, or textiles made from the fibers, with a pre-formed complex containing sulfamic acid and urea, wherein the sulfamic acid is present in a sufficient amount to prevent misting of the urea when the complex is heated.
These and other objects of the present invention are achieved by providing a process for making fabrics containing cellulosic fibers, particularly cotton fibers, resistant to cross-staining. More particularly, the fabrics become resistant to being stained by anionic coloring agents that may undesirably contact the fabric during the manufacture of the fabric or during laundering or some other aqueous process. Furthermore, fibers used in cotton carpeting become resistant to being stained by accidental spillage.
The process includes the steps of providing a fabric containing cotton fibers. The fabric can be pre-dyed and/or can be in a substantially finished state. The fabric is contacted with a solution that includes a pre-formed complex. The complex contains a derivatising agent. For instance, the agent can be sulfamic acid. In addition, the complex can also contain other materials, such as urea.
Once contacted with a derivatising agent contained within the pre-formed complex, the fabric is heated to a temperature sufficient for the agent to react with the cellulosic fibers contained within the fabric. Through this reaction, the anionic charge of the cellulosic fibers is increased for making the fibers more resistant to anionic coloring agents during casual contact. Moreover, the use of a pre-formed complex allows such an anionic charge to be achieved at relatively low temperatures.
Although the combination of sulfamic acid and urea will sulfate cotton, it is but one of several methods according to the present invention of permanently rendering cotton anionic in charge. It is the anionic charge and not the reagents or structure of the anionic derivative that matters, but the negative (anionic) charge itself that is the means of achieving the benefits of this invention.
For most applications, the process of the present invention is used to protect predyed and pre-formed fabrics from staining during consumer laundering. It should be understood, however, that the process of the present invention can also be used to treat fibers themselves prior to being formed into a fabric or garment.
As described above, in one embodiment, the sulfating agent is sulfamic acid. In this embodiment, the sulfating agent can be carefully mixed with an amide of a carboxylic acid, such as urea under controlled conditions, to form a complex prior to being applied as an aqueous solution to the fabric or fibers. It is unknown at this time what type of complex is formed between the sulfating agent and the amide of the carboxylic acid. As used herein, the term “complex” is intended to cover any chemical association or bond. Urea is not o
Bella Otto
Login Robert B.
Wicker, Jr. Calvin McIntosh
Bayer Corporation
Dority & Manning P.A.
Einsmann Margaret
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