Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Cellulose fibers
Reexamination Certificate
2001-06-14
2003-03-25
Hardee, John (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Cellulose fibers
C008S116100
Reexamination Certificate
active
06537327
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to textile manufacturing and treating processes comprising hydrophobically modified polymers. The polymers are especially useful in preventing the backstaining of denim during a stonewashing process.
BACKGROUND OF THE INVENTION
The production of “aged” denim garments is obtained by nonhomogeneous removal of indigo dye trapped inside the fibers by the cooperative action of cellulase enzymes and mechanical factors such as beating and friction. However, when cellulases are present, the removed indigo backstains the reverse side of the fabric which is undesirable.
WO 9325655 describes enzymatic compositions for stonewashing. Indigo backstaining which occurs in the presence of cellulase enzymes is described in an article entitled, “
Indigo Backstaining During Cellulase Washing
” Cavaco-Paulo et al., Textile Res. J. 68(6), 398-401 (1998).
Conventional anti-dye transfer polymers such as polyvinylpyrrolidone and polyvinylpyrridine-N-oxide are effective for preventing the redeposition of direct dyes that are typically used on cotton. However, such conventional anti-dye transfer polymers are not effective in preventing the backstaining of indigo dyes due to the extreme hydrophobicity of indigo dyes.
Discoloration is also a problem in textile bleaching processes wherein heavy metal ions and salts are present. For example, bleaching by hydrogen peroxide is generally carried out under an alkaline condition of a pH value of 10 to 14, and the reaction effectively improving the whiteness is represented by the formula: H
2
O
2
→HO
−
2
+H
+
, the active bleaching component is the perhydroxyl ion. However, under alkaline conditions (pH of at least 10), the side reaction represented by the formula: 2H
2
O
2
→2H
2
O+O
2
is promoted by heavy metal ions which are contained in cellulose fibers of cotton, flax or the like, and in a bleaching bath, such as iron, calcium, copper and manganese, and therefore, discoloration of the fibers occurs, and the fibers are made brittle.
To eliminate this disadvantage, sodium silicate is frequently used as a bleach stabilizer, but the use of sodium silicate is disadvantageous in that water-insoluble salts of calcium and magnesium, i.e., silicate scales, are formed, and these insoluble salts adhere to and are deposited on a bleached textile and a bleaching apparatus to cause a silicate scale problem.
Bleach stabilizers other than sodium silicate include polyphosphoric acid salts such as sodium tripolyphosphate, and aminocarboxylate organic chelating agents such as ethylenediamine-tetraacetic acid (EDTA) and diethylenetriamine-pentaacetic acid (DTPA). These bleach stabilizers do not cause a silicate scale problem, however, at a pH of 10 to 14, the chelating capacity is reduced. Moreover, these bleach stabilizers are insolubile in the presence of an excessive amounts of hardness ions.
Heavy metal ions also cause problems in the desizing, scouring, mercerising, and dyeing processes of textiles by forming insoluble salts. The insoluble salts deposit on textiles and equipment causing scale problems and blemishes on textiles.
SUMMARY OF THE INVENTION
The present invention provides a textile manufacturing or treating process comprising treating a textile with a solution or dispersion of a hydrophobically modified polymer having a hydrophilic backbone and at least one hydrophobic moiety,
wherein said hydrophilic backbone is prepared from at least one monomer selected from the group consisting of ethylenically unsaturated hydrophilic monomer selected from the group consisting of unsaturated C
1
-C
6
acid, amide, ether, alcohol, aldehyde, anhydride, ketone and ester; polymerizable hydrophilic cyclic monomer; non-ethylenically unsaturated polymerizable hydrophilic monomer which is selected from the group consisting of glycerol and other polyhydric alcohols; and combinations thereof,
wherein said hydrophilic backbone is optionally substituted with one or more amino, amine, amide, sulfonate, sulfate, phosphonate, hydroxy, carboxyl or oxide groups;
wherein said hydrophobic moiety is prepared from at least one hydrophobic monomer or a chain transfer agent, said hydrophobic monomer is selected from the group consisting of a siloxane, saturated or unsaturated alkyl and hydrophobic alkoxygroup, aryl and aryl-alkyl group, alkyl sulfonate, aryl sulfonate, and combinations thereof, and said chain transfer agent has 1 to 24 carbon atoms and is selected from the group consisting of a mercaptan, amine, alcohol, and combinations thereof,
wherein said hydrophobically modified polymer is present in an amount of from 0.001 to 50 weight percent, based on the total weight of the solution or dispersion.
According to another aspect, the invention provides a method to prevent the backstaining of denim during a stonewashing process comprising adding 0.001 to 50 weight percent, based on the total weight of the solution or dispersion, of a solution or dispersion of the hydrophobically modified polymer.
The hydrophobically modified polymers prevent redeposition of indigo onto denim in a stonewashing process, help stabilize hydrogen peroxide in a bleaching process, reduce scale and prevents deposition of heavy metal ions such as iron, calcium and magnesium in a scouring, desizing, and mercerising process, and disperse direct and disperse dyes, and suspend unfixed dyes in order to provide a consistent and level dyeing of textiles in a dyeing process.
An additional advantage is that the hydrophobically modified polymers complex salts, such as calcium, magnesium and iron salts, during the dyeing process which prevents the salts from depositing on the textiles and causing blemishes, or precipitating the dyes out of solution which reduces the efficiency of the dyes. The hydrophobically modified polymers also suspend polyester trimers during the dyeing of polyester.
DESCRIPTION OF THE INVENTION
The invention provides a textile manufacturing or treating process comprising a solution or dispersion of a hydrophobically modified polymer. Such textile manufacturing and treating processes include stonewashing of denim, desizing, scouring, mercerising, bleaching, and dyeing processes. As used herein, these terms have the following meanings:
(1) “Stonewashing” refers to the production of “aged” denim garments with cellulase enzymes in the presence of mechanical factors such as beating and friction.
(2) “Desizing” is essentially a part of the scouring process, and rapid removal of size is important especially in continuous preparation processes. Desizing of sized fabrics is commonly carried out using water washing at varying temperatures or with enzymes. Desizing can also be carried out effectively with alkaline, preferably caustic solutions, and those alkaline solutions can be very dilute.
(3) “Scouring” involves removing or reducing the level of fats, waxes, oils, dirt, and so forth on a textile. Apart from the aesthetic benefits of clean fabric, the major reason for scouring is to improve the extent and uniformity of absorbency for subsequent processes, especially dyeing. Scouring generally takes place using mild alkalinity and surfactants as wetting agents, such as alkylbenzenesulfonate and alkylphenol ethoxylates. It is noted that scouring is particularly important with natural fibers which contain much more extraneous matter than synthetic fibers. For example, cotton, requires high alkalinity scouring, which swells the fibers, allowing access to the lumen and removing soil from the surface.
(4) “Bleaching” involves bleaching of the various types of textiles with a peroxide bleaching compound. Suitable peroxide compounds are water soluble peroxides, particularly alkali metal peroxides, preferably sodium peroxide, and hydrogen peroxide, the latter being particularly preferred. The peroxide bleaching is carried out in an alkaline medium. To achieve the alkaline conditions, it is advantageous to use an alkali metal hydroxide, preferably potassium or sodium hydroxide.
(5) “Mercerising” is used to swell cotton fibers in order to increase t
Hardee John
National Starch and Chemical Investment Holding Corporation
Roland, Esq. Thomas F.
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