Bleaching and dyeing; fluid treatment and chemical modification – Reactive dye composition – process – or product
Reexamination Certificate
2001-02-27
2002-12-24
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Reactive dye composition, process, or product
C008S647000, C008S557000, C008S558000
Reexamination Certificate
active
06497732
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to the field of fiber and textile dyeing. More specifically, this invention relates to polymeric dyes and their use in providing substantially permanent retention of dye color in textiles. Such polymeric dyes may also improve the hand of the fabric.
BACKGROUND OF THE INVENTION
Dye retention on fabrics is important to retain the original shade of the garment. There are a number of different classes of dyes that are used to color cotton and other cellulosics. One group is the direct dyes. These are dyes that are typically inexpensive, water-soluble and have large, planar aromatic structures. The cloth is simply dipped in a solution of the dye, padded, dried, and then washed. While cost of the dyestuff and dye application is low, the washfastness (dye retention following laundering) is poor.
Reactive dyes are dyes containing reactive groups, often derivatives of cyanuric chloride or containing vinyl sulfone groups (or those that can be converted into vinyl sulfones). In dyeing, cotton is typically padded with caustic and dried, and then padded with the reactive dye and dried, and finally heated/steamed for about 15 minutes and washed. The washfastness of reactive dyes is much higher than that of direct dyes. However, application is more complex and costly and the dyes are more expensive.
Vat dyes are applied in a reduced and alkali-soluble form (the leuco form). They revert back to their insoluble structures upon exposure to air. Disadvantages of this technology include the need for a reducing agent and possible poor washfastness, as there is no chemical bond between the fiber and the dye. Sodium hydrosulfite, which is commonly used as the reductant, is fairly expensive and may be an environmental hazard.
Sulfur dyes are important for cotton, although their structures are often poorly defined. They can often be applied in a water-soluble form: dye-S—SO
3
Na (dye-thiosulfate) in the presence of sodium sulfide. When heated, the sulfide ion causes a coupling of the dyes to occur via an S—S bond through a loss of the —SO
3
Na group. The loss of these hydrophilic groups decreases the solubility of the product. If there is more than one thiosulfate group on the dye molecule, an insoluble polymer may be produced. However, in general no covalent bond to the fiber is made.
To dye nylon (and wool), acid dyes are commonly used, Acid dyes are named as such because they are applied from weakly acidic baths (pH 2-6). Chemically, the functional groups on these dyes are usually the same as those found in the direct dyes, including sulfonate, hydroxyl, amine, and nitro groups. Like the direct and reactive dyes, these dyes are usually water-soluble and are often synthesized via azo coupling chemistry. Acid dyes dye wool through an ion exchange mechanism. Because wool is drycleaned with organic solvents, the water solubility of these dyes does not usually present a problem.
Polymeric dyes have been disclosed for use in the food industry, because they are not readily absorbed by the body when eaten, and for use in printing inks.
SUMMARY OF THE INVENTION
This invention is directed to textile dye preparations useful for the permanent or substantially permanent dyeing of textiles and other webs.
More particularly, the invention is directed to fiber-reactive polymeric dyes, which comprise a dye covalently bound to a carboxyl-containing polymer. By “fiber-reactive” is meant that the polymeric dye will form a chemical covalent bond with the fiber, textile, or web to be treated, via functional groups for binding or attachment to the fibers of the textiles or other webs to be dyed. The invention also encompasses textile dye preparations comprising a solution or suspension of the fiber-reactive polymeric dye. The resulting polymeric dye preparations have improved colorfastness and retention on the textile or web fiber structure, even after a large number of washings.
The invention is further directed to the process for treating textiles and other webs with the fiber-reactive polymeric dyes, wherein the fiber-reactive polymeric dye preparation is applied to the fiber, yarn, textile, or other web. In a presently preferred embodiment, the application process is a dip-pad-cure process. That is, the web is placed into the dye preparation (dipped), then padded and cured in a single continuous process. This greatly increases the efficiency of the treatment.
This invention is further directed to the yarns, fibers, fabrics, textiles, finished goods, or nonwovens (encompassed herein under the terms “textiles” and “webs”) treated with the fiber-reactive polymeric dye preparation. Such textiles and webs comprise a covalently attached polymeric dye and exhibit a greatly improved colorfastness and resistance to fading in comparison to textiles and webs treated by prior art dyes, even after multiple launderings.
DETAILED DESCRIPTION OF THE INVENTION
The textile-reactive preparation of the invention comprises a combination of a dye and a carboxyl-containing polymer to give polymeric dyes that are reactive to the fibers of textiles or other webs. The polymeric dye includes functional groups for binding or attachment to the fibers of the textiles to be treated. The resulting fiber-reactive polymeric dye preparations have improved colorfastness and retention on the textile or web fiber structure.
The polymeric dyes of the invention are formed, in one embodiment, by dispersing a carboxyl-reactive dye and a carboxyl-containing polymer in a suitable solvent. The reaction solution may be, and preferably is heated. The dye and the polymer react together by covalent bonding to give a fiber-reactive polymeric dye.
The term “carboxyl-reactive dye” as used herein refers to a water-soluble dye that contains groups that can react with carboxyl groups. Such carboxyl-reactive groups include amine, hydroxyl, vinyl sulfone, C—Cl in cyanuric chloride, and the like, which groups are well-known to those skilled in the art. The dye may be a direct dye or an acid dye, which are easily obtained and are inexpensive, but which do not normally exhibit good colorfastness. However, any dye with the appropriate reactive groups may be used in this invention, including disperse dyes, mordant dyes, solvent dyes, and pigments.
The term “carboxyl-containing polymer” as used herein refers to a polymer that contains carboxyl groups. The number of carboxyl groups on the polymer should be such that there will be sufficient carboxyl groups remaining after reaction with the carboxyl-reactive dye so that the groups can be re-formed into a reactive anhydride by a catalyst when the catalyst and the fiber-reactive polymeric dye are heated in the presence of a material that contains hydroxyls or amines (such as, for example, cotton or wool). Such polymers include, but are not limited to, poly(acrylic acid) and copolymers that contain acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride, for example. In a presently preferred embodiment, the polymers are of low molecular weight; that is, they will have a molecular weight of less than 10,000. In another preferred embodiment, the polymer is poly(acrylic acid), which is inexpensive and readily available. In yet another preferred embodiment, the polymer is a copolymer of butadiene/maleic anhydride (“maleinized polybutadiene”), which in addition to being inexpensive also gives a superior hand to the treated textile.
In one example of the preparation of a fiber-reactive polymeric dye, maleinized butadiene and a carboxyl-reactive dye are dissolved in a solvent such as methylethylketone or tetrahydrofuran. The mixture is then refluxed until reaction occurs, or the solvent is removed by rotary evaporation and the mixture is heated to drive a reaction. In a second example, polyacrylic acid and a carboxyl-reactive dye are dissolved in water, after which the water is evaporated off at elevated temperature and the dye/polymer mixture is heated to drive a reaction.
In another embodiment of the invention, the fiber-reactive dyes ar
Green Eric
Lau Ryan
Linford Matthew R.
Soane David S.
Einsmann Margaret
Larson Jacqueline S.
Nano-Tex, LLC
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