Bleaching and dyeing; fluid treatment and chemical modification – Reactive dye composition – process – or product
Reexamination Certificate
2001-03-19
2003-06-24
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Reactive dye composition, process, or product
C008S111000, C008S149300, C008S151000, C008S931000
Reexamination Certificate
active
06582478
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Applicant claims priority under 35 U.S.C. §119 of German Application Nos. 198 43 046.9 and 198 43 047.7 both filed Sep. 19, 1998. Applicant also claims priority under 35 U.S.C. §120 of PCT/DE99/02903 filed Sep. 9, 1999. The international application under PCT article 21(2) was not published in English.
DESCRIPTION
The invention relates to a method for the pretreatment, specifically for the desizing and boiling off as well as bleaching, if need be, of cellulose materials, by which a treatment mixture of a pretreatment agent containing per-compounds such as hydrogen peroxide is applied to the cellulose material and caused to act as intended in the pretreatment. Furthermore, the invention relates to a method for applying the treatment agents in the reactive dyeing and dye fixation of cellulose material, by which the material is pretreated, specifically desized, boiled off and/or bleached before the dye is fixed.
The term “web-shaped cellulose material” is understood to relate to flat textile structures made of cellulose, including cotton, viscose, regenerated cellulose as well as its mixtures among each other, and/or made of synthetic fibers. The method is intended to be applied primarily in conjunction with flat textile structures such as woven or meshed textile structures; however, its application in connection with threads or ribbons of thread is possible as well. Suitable per-compounds, briefly “per”, which split off oxygen in solution preferably by decomposition of hydrogen peroxide, within the meaning of the invention are, for example perborates or percarbonates. The respective treating agent is preferably applied by immersion in a bath containing the treatment agent.
The process steps desizing and boiling off as well as bleaching, if need be, are part of the preparation process, the so-called “pretreatment” in the finishing of textiles. The purpose of desizing is to remove all substances that were previously applied to the fiber in the sizing process. Various methods of desizing are available that conform to the sizing agents employed in the given case. Starch-containing sizing agents can be desized with the help of enzymes; in other cases, oxidative desizing is required. The natural impurities of cotton such as fat, waxes, pectins etc. render such a cellulose product hydrophobic and are therefore removed as “dirt” in a generally alkaline boiling-off process, for example with sodium peroxide.
Following desizing and, if need be, boiling off, many textiles have a undefined yellowish color impression that is often removed prior to subsequent dyeing by bleaching if a defined color shade is to be obtained. In the treatment of cotton and other native as well as regenerated cellulose fibers, hydrogen peroxide bleaches, among other things, are almost always used in conjunction with sodium hydroxide and other chemicals.
In many of the known desizing, boiling-off and bleaching processes, a separate plant, for example a desizing, a boil-off and a bleaching plant is required for each of the process stages. Such plants are frequently not operated continuously because dwelling times of several hours are to some extent required for permitting the respective chemical to act. The expenditure in terms of machines, space and operating costs is consequently substantial. Another drawback is the time expenditure of at least 1 hour needed in most cases in connection with the usual dwelling times. If the work is carried out at high temperatures in order to reduce the process, the energy costs rise accordingly.
A combined desizing, washing and bleaching process for raw textiles made of cotton, which is carried out continuously, is described in CH 560 789. In said process, the cellulose material is wetted with an aqueous solution that contains as important components alkali metal hydroxide as well as per-compounds such as hydrogen peroxide and peroxide phosphate. The material is heated to a treatment temperature of about 80° to 135° C. At treatment temperatures of 100° C. and normal pressure, the treatment vessel contains 100% by vol. steam. At the temperature limit of 80° and normal pressure, which is specified in the prior art, almost 100% by vol. steam is reached in the treatment vessel as well. Following the heat treatment, the material is washed. Short treatment times of down to 1 minute are possible only at 135° C. and 100% by vol. steam in the pressure vessel and consequently only discontinuously.
During the known steam treatment of the material loaded with the pretreatment agent at approximately 100% by vol. steam, the moisture content of such material is maintained approximately constant in accordance with the steam content of the treatment chamber. However, the per-compounds, in particular hydrogen peroxide, contained in the pretreating agent decompose during that time in accordance with the relatively high temperature. As a result, the content of per-compounds in the (approximately constantly moist) textile material is constantly reduced. As the concentration of the per-compounds decreases, their desired pretreatment effect (per time unit) is diminished as well. Therefore, in the known art it is necessary to work with relative high excess amounts of per-compounds. According to CH 560 789, substantial treatment times are nonetheless needed if the work is not to be carried out discontinuously in pressure vessels at temperatures of close to 135° C.
However, in the steam atmosphere (100% by vol. steam) for which provision is made in the aforementioned patent CH 560 789, the amount of per-compound used is not nearly completely degraded. This, however, is not permissible because the reactive effect of the per-compounds would otherwise increasingly drop toward the end of the pretreatment process (and the reaction time required for the pretreatment would become increasingly longer). Therefore, the per concentration still remains so high at the end of the pretreatment that the material has to be washed after the treatment has been completed. This applies specifically if such treatment is followed by a subsequent dyeing process because the dyestuff can be damaged by per-substances.
For a discontinuous peroxide bleaching step preceding the dyeing of cellulose material, it is proposed in DE 39 06 769 A1 to first add glyoxal or glyoxalic acid to the bath to be used for dyeing. Such substances are expected to neutralize those per compounds that remained on the material from the peroxide bleach, if possible without any interconnected washing step. The additional chemicals lead to contamination of the waste water accordingly.
A very similar process for dyeing in reactive dyestuffs after a bleaching process is disclosed in U.S. Pat. No. 5,378,245. The treatment bath used for bleaching contains hydrogen peroxide. The bath is permitted to act on the material for 45 to 60 minutes at 70 to 120° C. As in the aforementioned documents CH 560 789 and DE 39 06 769, the bleaching process thus takes place at almost 100% by vol. air humidity in the treatment chamber and without any drying of the material. The hydrogen peroxide components accordingly remaining on the material with the wet bleaching process used in the present case as well, are therefore neutralized with a reducing agent before the dye is applied in order to protect the dyes against the peroxide.
DE 31 24 961 A1 describes a discontinuous process for simultaneous dyeing and desizing. This is a cold-dwelling process in which dyes and desizing agent (amylase) as well as soda are added to the treatment bath. Following immersion and squeezing off and a bath absorption of about 70%, the textile material is rolled up and, wound in a plastic foil, stored for 24 hours at about 20° C. while slowly rotating. The material is subsequently passed through a boiling soap bath, among other things. If the material has to be bleached, the soap bath may contain the bleaching hydrogen peroxide because the simultaneous dyeing and desizing process cannot be combined with the bleaching step, as the bleaching agent would damage the dye
A. Monforts Textilmaschinen GmbH & Co.
Collard & Roe P.C.
Einsmann Margaret
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