Bleaching and dyeing; fluid treatment and chemical modification – Bleaching – Chemical
Reexamination Certificate
2001-02-15
2004-12-14
Boyer, Charles (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Bleaching
Chemical
C008S101000, C510S276000, C510S286000, C510S302000, C510S362000, C510S372000, C510S375000
Reexamination Certificate
active
06830591
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the use of hydrophobic bleaching systems in textile preparation and, more particularly, to the use of activated peroxide bleaching via hydrophobic activators or hydrophobic peracids on woven or knitted fabrics, fibers or yarns.
BACKGROUND OF THE INVENTION
In the textile processing of natural fibers, yarns and fabrics, a pretreatment or preparation step is typically required to properly prepare the natural materials for further use and in particular for the dyeing and/or finishing stages typically required for commercial goods. These textile treatment steps remove impurities and color bodies, either naturally existing or those added by the spinning and weaving steps to the fibers and/or fabrics.
While textile treatments may include a number of varying treatments and stages, the most common include: singeing—the removal of loose or miscellaneous fibers from the surface by burning with a flame; de-sizing—the removal of sizing agents, such as starches, via enzymatic soaking; scouring—the removal of greases, oils, waxes and fats by contact with a solution of sodium hydroxide at temperatures near boiling; mercerization—the application of high levels of sodium hydroxide in conjunction with stretching and pulling of the fabrics for increased fiber strength.
An additional common pretreatment step involves a bleaching step to destroy naturally occurring color bodies. The bleaching step provides a uniform white appearance for consumer acceptable whites as well as provides a uniform color base for dyeing or printing. Thus, a highly successful bleaching step is necessary for commercially acceptable consumer fabrics. Traditional textile bleaching of natural fibers has involved the use of hydrogen peroxide. Hydrogen peroxide has gained its wide acceptance due to its flexibility of use being capable in both hot and rapid or cold and long dwell bleaching processes and due to its environmental friendliness.
While hydrogen peroxide has gained wide spread acceptance in the textile industry, it is not a particularly effective bleaching agent. Hydrogen peroxide, as commercially supplied, is an extremely stable compound and as a result has only a slight bleaching effect on natural fibers. To overcome its weak activity, extremely high temperatures and/or extremely long bleaching times are required in commercial processes in addition to activation of the peroxide. That is, temperatures in excess of 95° C. are typically required. In addition, activation of the peroxide via the use of alkali, sulfuric acid, uv irradiation, hypochlorite or organic activators is also necessary with alkali being the most preferred. Not only do these drawbacks result in excessive cost associated with commercial textile peroxide bleaching, but the high temperatures and/or long contact times result in significant fiber damage and strength reduction of the resultant yarns and fabrics.
Organic activators have been attempted in textile bleaching systems to little success. Tetra acetyl ethylene diamine or TAED is a common hydrophilic bleach activator widely Ad accepted in the consumer laundry bleaching applications to provide effective bleaching at lower wash temperatures. TAED has been taught in hydrogen peroxide textile bleaching, and in particular in the bleaching of regenerated cellulosics such as rayon. However, while TAED has allowed lower bleaching temperatures, it has proven to provide little advantage in the fiber damage and fiber strength of cellulosics such as rayon. In addition, the poor water solubility of TAED limits its application in textile processing.
Hydrophobic bleach activators, such as nonanoyloxybenzene sulfonate, sodium salt (NOBS) have been employed in consumer laundry detergent applications such as Tide® with Bleach to work in conjunction with peroxygen sources to provide activated bleaching in consumer laundering of garments. Activated bleaching in consumer home laundry conditions allows effective cleaning of certain soils and stains in cold water temperatures. However, the use of hydrophobic systems has been limited in a home consumer laundry environment due to the formation of diacyl peroxides in the wash solution. Diacyl peroxides degrade natural rubber components into which they come in contact. Thus, sump hoses, rubber gaskets, etc in laundry machines have prevented explotation of this technology in certain geographies.
The severe conditions employed in the bleaching of textiles have heretofore prevented the successful application of laundry detergent bleaching technology in textile mill applications. Indeed, EP 584,710 discloses the use of activated bleaching in textile mill applications wherein NOBS is briefly disclosed along with a multitude of other classes and types of activators. While NOBS is disclosed, there is no successful application of hydrophobic bleaching technology where acceptable whiteness values are achieved while damage to fabrics and fibers is minimized. Indeed, EP 584,710 specifies that in order to achieve acceptable whiteness benefits, additional alkali bleaching is necessary which will dramatically increase fiber damage.
Accordingly, the need remains for an effective textile treatment process and in particular for improved hydrogen peroxide bleaching for textile treatment which can provide superior whiteness benefits at reduced bleaching temperatures and times while providing improved fabric strength retention versus conventional textile bleaching processes.
SUMMARY OF THE INVENTION
This need is met by the present invention wherein a method for the treatment of textiles using activated peroxygen bleaching with hydrophobic bleaching systems is provided. The process involves the use of a hydrogen peroxide and a hydrophobic bleach activator or a hydrophobic peracid. The use of a hydrophobic bleaching agent provides superior whiteness and fabric strength and fiber damage benefits, i.e. strength retention to fibers, yarns and fabrics and less fiber damage. In addition, the method of the present invention allows for cost reduction in the operation of a textile bleaching process through the use of significantly lower bleaching temperatures than conventional peroxide bleaching and much shorter processing times, particularly in batch processing.
While not wishing to be bound by theory, it is believed that the hydrophobic bleaching agent of the present invention provide better absorbency on the fabrics and yarns and better “wetting” of the surface of the fibers than conventional peroxide bleaching techniques or hydrophilic activators. Hydrophobic bleach activators form the active bleaching species, peracid, on the surface of the fabric allowing a longer time on the surface of the fabric. Hydrophilic activators, meanwhile, form peracid in solution and must then undergo a fabric solution interaction which is less efficient. As a result, the hydrophobic bleaching agents of the present invention provide superior bleaching and whiteness while minimizing fiber damage and strength reduction.
According to a first embodiment of the present invention, a method for the treatment of non-finished textile components is provided. The method comprises the steps of providing a non-finished textile component such as a fiber, yarn or fabric, saturating the textile component with an aqueous bleaching solution comprising hydrogen peroxide and a hydrophobic bleaching agent such as a hydrophobic activator or a pre-formed hydrophobic peracid, and allowing the bleaching solution to remain in contact with the textile component for a period of time sufficient to bleach the textile component to a CIE whiteness of at least 70.
Preferably, the bleaching solution comprises hydrogen peroxide and a hydrophobic bleach activator which is selected from the group consisting of:
a) a bleach activator of the general formula:
wherein R is an alkyl group having from about 5 to about 17, preferably from about 7 to about 11, carbon atoms and L is a leaving group;
b) a bleach activator of the general formula:
or mixtures thereof, wherein R
1
is an alkyl, aryl, or a
Moe Kevin David
Wang Jiping
Washington Nodie Monroe
Bolam Brian M.
Boyer Charles
Corstanje Brahm J.
The Procter & Gamble & Company
William Zerby Kim
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