WO2000061856A1

WO2000061856A1 - A process for stabilizing dyed textiles against yellowing

Info

Publication number: WO2000061856A1
Application number: PCT/EP2000/002739
Authority: WO
Inventors: Bernd Wahle; Thomas Leung; Gero Reichert
Original assignee: Cognis Deutschland Gmbh
Priority date: 1999-04-07
Filing date: 2000-03-29
Publication date: 2000-10-19
Also published as: DE19915439A1

Abstract

Textiles dyed with vattable dyes can be stabilized against yellowing by treatment with an aqueous liquor containing fluorine-containing polymers and/or copolymers or perfluoroalkyl (meth)acrylate and non-fluorinated alkyl (meth)acrylate.

Description

A Process for Stabilizing Dyed Textiles Against Yellowing

This invention relates to a process for stabilizing dyed textiles against yellowing, to an aqueous liquor for stabilizing dyed textiles against yellowing and to the use of certain fluorine-containing polymers for stabilizing dyed textiles.

Dyed textiles, particularly those dyed with vattable dyes, such as indigo, turn yellow when stored in air. The reason for this is the reaction of ozone or nitrogen oxides (NOχ) or other oxidizing gases which are present in traces in the atmosphere with the textile dye. Indigo-dyed textiles, for example blue jeans, are particularly sensitive to the effect of such oxidizing agents. The yellowing effect, i.e. the lightening or displacement of the color tone, is particularly troublesome in the shipment and storage of the textiles at the commercial level. A troublesome change in color occurs on the outside of stacked garments, above all denim garments and particularly those with a stonewash appearance. This change in color is attributable to the formation of oxidation products - isatin in the case of indigo. Although the oxidation products can be removed from the textiles by washing with cold water, the textiles are still left with light patches.

Accordingly, the problem addressed by the present invention was to provide a process for stabilizing textiles dyed with vattable dyes against yellowing.

A first embodiment of the invention relates to a process for stabilizing textiles dyed with vattable dyes against yellowing, characterized in that the dyed textile is treated with an aqueous liquor which contains at least one polymer produced at least from (meth)acrylic acid monomers containing polyfluorinated alkyl groups and/or at least one copolymer produced from at least the following monomers:

a) (meth)acrylic acid containing polyfluorinated alkyl groups b) alkyl (meth)acrylates,

and the textile is subsequently dried.

The textile consists predominantly of cellulose fibers or contains cellulose fibers in admixture with other fibers, for example polyester fibers, polyacrylonitrile fibers, polyamide fibers, polyurethane fibers, wool or cellulose acetate fibers. However, textiles of cotton fibers or textiles predominantly containing cotton fibers are particularly preferred. The textile is present in the form of a dyed and preferably made-up garment, for example pants, jackets or skirts which are completely or partly dyed with vattable dyes. Vattable dyes are, for example, anthraquinone dyes, indigo dyes and sulfur dyes.

However, the process according to the invention is particularly suitable for stabilizing made-up indigo-dyed textiles, preferably denim, against yellowing. Denim garments are often available in a stonewash finish, in which case they are particularly sensitive to yellowing. This yellowing can be successfully reduced by treating the textile by the claimed process. Fluorine-containing polymers and/or copolymers are used. The monomers used are, on the one hand, fluorine-containing (meth)acrylates a) and, on the other hand, non-fluorinated alkyl (meth)acrylates b), the polymers or copolymers being obtained in known manner, for example by emulsion polymerization. Alcohols, such as isopropyl alcohols, glycols, more particularly propylene glycols, or ketones, such as acetone or methyl ethyl ketone, are preferably used in the emulsion polymerization process.

The polymers and copolymers themselves are compounds known per se which are synthesized either solely from the monomer unit a) or, in the case of the copolymers, at least from a) and b). The monomers a) correspond to general formula (I):

R¹-X-OCOR=CH₂ (I)

in which R¹ is a polyfluorinated alkyl group and X is a difunctional organic radical which preferably corresponds to the formula (CY₂)_n, where Y may be a hydrogen and/or fluorine atom and n is a number of 2 to 10, and R is a hydrogen atom or a methyl group. In the polyfluorinated group R¹, 60% of the hydrogen atoms are preferably replaced by fluorine atoms. In a particularly preferred embodiment, all the hydrogen atoms in R¹ are replaced by fluorine (so-called perfluorinated compounds). The alkyl group R¹ preferably contains between 1 and 22 carbon atoms, more preferably between 2 and 20 carbon atoms and most preferably between 6 and 16 carbon atoms. Groups containing 8 to 12 carbon atoms are most particularly preferred. The fluorine-containing monomers a) are condensed either on their own or with fluorine-free (meth)acrylic acid or alkyl (meth)acrylic acid b) to form the compounds according to the invention. In the context of the invention, acrylates and methacrylates are collectively referred as (meth)acrylates. Suitable alkyl (meth)acrylates b) contain in particular 3 to 20 carbon atoms and at least one (meth)acrylic acid group in the molecule. The alkyl group is linear, branched or cyclic. Suitable monomers b) are, for example, octadecyl (meth)acrylate, hexadecyl (meth)acrylate, behenyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, t-butyl (meth)acrylate, n-butyl (meth)acrylate, cyclohexyl (meth)acrylate and/or isopropyl (meth)acrylate.

Besides the monomers a) and b), the polymers or copolymers according to the invention may contain other monomer units, for example ethylene, allyl acetates, vinyl acetate, vinyl alkyl ether, vinyl fluoride, vinyl alkyl ketones, styrene and derivatives thereof, (meth)acrylamides, hydroxyalkyl (meth)acrylates, butadiene and/or isoprene. It is of advantage to use copolymers of the units a) and b). In this case, the monomers a) preferably make up between 10 and 90% by weight and the monomers b) also between 10 and 90% by weight of the monomers used. Up to 30% by weight of the other monomers may be present. Copolymers consisting solely of monomer units a) and b) are preferably used in the process according to the invention. The polymers and/or copolymers preferably contain fluorine monomers in percentages by weight of 25 to 85% by weight, based on the weight of the polymer or copolymer as a whole. Cationic polymers of the type described above are also preferred. Depending on the production process, the polymers may contain other ingredients, such as solvents or emulsifiers, in small quantities. Particularly suitable polymers in the process according to the invention are the products marketed by Henkel KGaA under the names of Repellan KFC, Repellan TFC and Repellan EPF.

The dyed textile, which is preferably already made up, is treated with the fluorine-containing polymers in the form of an aqueous dispersion. This aqueous dispersion may be applied by any of the techniques known in the textile industry, for example padding, spraying or foam application, etc. The treatment takes place for at least 5 minutes at room temperature (21 °C), although longer times and/or higher temperatures, for example 30 to 60 minutes at 20 to 80°C, may also be applied. The treatment liquor contains the fluorine-containing polymer or copolymer in quantities of preferably 5 to 50 g/l, more preferably 15 to 40 g/l and most preferably 20 to 30 g/l. Besides the fluorine-containing polymers or copolymers, the liquors used in the process according to the invention may also contain other typical auxiliaries, such as wetting agents and/or emulsifiers. On completion of the treatment, the textiles are dried in the usual way and the polymer and/or copolymer is thus fixed to the fibers. This is preferably done at temperatures of 80 to 200°C and, more preferably, at temperatures of 100 to 160°C, the duration of the treatment preferably being between 1 and 40 minutes. A drying roller or a tenter frame may be used for drying the textiles. The textiles are preferably dried on a tenter frame in the process according to the invention. Normal drying times are between 3 and 30 minutes. It can be of advantage to dry the textile in several stages, optionally at different temperatures, in order for example first to remove the water and then to guarantee fixing of the finish on the fibers. Thus, it can be of advantage to carry out drying first for 1 to 10 minutes at 80 to 120°C and then for another 10 to 20 minutes at higher temperatures, preferably at 100 to 200°C.

In another embodiment, the present invention relates to aqueous textile treatment liquors which contain between 5 and 50 g/l of a fluorine-containing polymer and/or copolymer as described above. The present invention also relates to the use of such fluorine-containing polymers and/or copolymers for stabilizing textiles dyed with vattable dyes against yellowing.

Example The process according to the invention was carried out on an MF168 denim cloth (100% cotton) from the Mou Fung weaving factory. Warp yarn: 7^s OE, 100% indigo, weft yarn 7^s OE. For desizing, the denim cloth was treated for 15 minutes at 60°C with an aqueous 1.5% by weight V-amylase liquor (Forylase NTL, Henkel KGaA). The denim cloth was then given a stonewash effect by enzymatic treatment for 45 minutes at 55°C with an aqueous liquor containing 1.5% by weight of cellulase (Forylase SWE, Henkel KGaA).

The denim cloth thus pretreated was then treated with a liquor containing 30 g/l of the copolymer according to the invention (Repellan KFC, Henkel KGaA). The cloth was then dried for 5 minutes at 140°C.

The denim cloth thus finished was subjected to an ozone yellowing test (AATCC 109, Levis). The cloths treated in accordance with the invention were awarded a score of 4 to 5 whereas untreated cloths were awarded a maximum score of 3. Cloths with a score of 4 are acceptable to the consumer. The maximum score awarded in this test is 5.

Claims

1. A process for stabilizing textiles dyed with vattable dyes against yellowing, characterized in that the dyed textile is treated with an aqueous liquor which contains at least one polymer produced at least from (meth)acrylic acid monomers containing polyfluorinated alkyl groups and/or at least one copolymer produced from at least the following monomers:

and the textile is subsequently dried.

2. A process as claimed in claim 1 , characterized in that indigo-dyed textiles are treated.

3. A process as claimed in claim 1 or 2, characterized in that denim garments are treated.

4. A process as claimed in claims 1 to 3, characterized in that jeans are treated.

5. A process as claimed in claims 1 to 4, characterized in that the polymers and/or copolymers are used in the form of an aqueous dispersion.

6. A process as claimed in claims 1 to 5, characterized in that the aqueous liquor contains the polymers and/or copolymers in quantities of 5 to 50 g/l, preferably in quantities of 15 to 40 g/l and more preferably in quantities of 20 to 30 g/l.

7. A process as claimed in claims 1 to 6, characterized in that the polymer and/or copolymer contains perfluoroalkyl (meth)acrylates with an alkyl chain length of C₈ to C-ι₂.

8. A process as claimed in claims 1 to 7, characterized in that the polymer and/or copolymer contains between 25 and 85% by weight of fluorine monomers, based on the weight of the polymer or copolymer.

9. A process as claimed in claims 1 to 8, characterized in that the textiles are treated with the aqueous liquor for at least 5 minutes at room temperature.

10. An aqueous textile treatment liquor containing between 5 and 50 g/l of a fluorine-containing polymer and/or copolymer according to claim 1.

11. The use of fluorine-containing polymers and/or copolymers according to claim 1 for stabilizing textiles dyed with vattable dyes against yellowing.