WO1994019529A1

WO1994019529A1 - A process for providing localized variation in the colour density of fabrics

Info

Publication number: WO1994019529A1
Application number: PCT/DK1994/000079
Authority: WO
Inventors: Thomas Vollmond; Henrik Lund; Annette Hanne Toft
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-26
Filing date: 1994-02-25
Publication date: 1994-09-01
Anticipated expiration: 1995-08-26
Also published as: DK21393D0; CN1121970A; AU6139394A

Abstract

Process for providing improved localised variation in the colour density of the surface of dyed fabrics, the process comprising treating a dyed fabric with a cellulytic enzyme in an aqueous liquor comprising a polymeric agent.

Description

A PROCESS FOR PROVIDING LOCALIZED VARIATION IN THE CO¬ LOUR DENSITY OF FABRICS

FIELD OF INVENTION

The present invention relates to processes of providing localized variation in the colour of dyed fabrics.

BACKGROUND OF THE INVENTION

The most usual method of providing a "stone-washed" look (localized abrasion of the colour) in dyed fabrics, in particular cellulose-containing fabrics, is by washing cellulose-containing fabrics or clothing made from such fabrics in the presence of pumice stones to provide the desired localized lightening of the colour of the fa¬ bric. Using pumice for this purpose has the disadvantage that pumice particles have to be washed from the fabric or clothing subsequently to treatment, and that the pumice stones and particles cause a significant wear of the machines used in the process. Also, handling large amounts of stones may be a problem.

Other approaches to providing a "stone-washed" appearan- ce to fabrics have therefore been suggested. For instan¬ ce, enzymes, in particular cellulytic enzymes, have been suggested for this purpose, either alone (4,832,864) or together with a smaller amount of pumice than required in the traditional process.

SUMMARY OF THE INVENTION

The present invention is based on the surprising finding that it is possible to obtain improved utilization of the ability of cellulytic enzymes to provide localized colour variations in dyed fabrics by adding a polymeric agent to the wash liquor. Accordingly, the present invention relates to a process for providing improved localised variation in the colour density of the surface of dyed fabrics, the process comprising treating a dyed fabric with a cellulytic enzyme in an aqueous liquor comprising a polymeric agent.

In the present context, the expression "improved local¬ ized variation" is intended to indicate that the differ- ences between lighter and darker areas of the fabrics is more pronounced than in fabrics treated by the enzymatic process described in, e.g. US 4,832,864. It has been found that in the known enzymatic "stone-washing" pro¬ cesses for obtaining localized colour variations, at least some (though not all) of the dye washed from the fabric is redeposited thereon so that the difference between darker and lighter shades on the fabric is some¬ what obscured (this phenomenon is known as backstaining to people skilled in the art) . It has surprisingly been found that by addition of a polymeric agent to the liquor in which the fabric is treated, such redeposition of dye may be significantly reduced. This effect is believed to be caused either by the polymer adsorbing to the fabric (so that redeposition of dye is sterically hindered) or by the polymer solubilising the dye.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, the concentration of poly- meric agent in the aqueous liquor is preferably between 0.1 mg/1 and 2 g/1. More preferably, the concentration of polymeric agent is 10-200 mg/1, dependent to some extent on the type of polymeric agent added.

Fabrics:

The process of the invention is most beneficially applied to cellulose-containing fabrics, such as cotton, viscose, rayon, ramie, linen or mixtures thereof, or mixtures of any of of these fibres with synthetic fibres. In particular, the fabric is denim. The fabric may be dyed with vat dyes such as indigo, direct dyes such as Direct Red 185, sulphur dyes such as Sulfur Green 6, or reactive dyes fixed to a binder on the fab¬ ric surface. In a most preferred embodiment of the pres¬ ent process, the fabric is indigo-dyed denim, including clothing items manufactured therefrom.

Cellulytic enzymes:

The cellulytic enzyme employed in the process of the invention may be any cellulase previously suggested for this purposes (e.g. as described in US 4,832,864). Thus, the cellulytic enzyme may be a fungal or bacterial cellulase. According to the invention, it has been found that both acid and neutral or alkaline cellulases may be employed. Examples of suitable acid cellulases are those derivable from a strain of Trichoderma. Irpex. Clostridium or Thermocellu sp. Examples of suitable neutral or alkaline cellulases are those derivable from a strain of Humicola. Fusarium. Bacillus. Cellulomonas. Pseudomonas. Mvceliophthora or Phanerochaete sp. A cur¬ rently preferred cellulase is a 43 kD endoglucanase obtainable from Humicola insolens (e.g. described in WO 91/17243) .

Polymeric agent:

According to the invention, the polymeric agent may be one which is capable of either adsorbing to the fabric in question or solubilising the dye in question. Examples of suitable polymers include proteins (e.g. bovine serum albumin, whey, casein or legume proteins) , protein hydrolysates (e.g. whey, casein or soy protein hydrolysate) , polypeptides, lignosulfonates, polysaccharides and derivatives thereof, polyethylene glycol, polypropylene glycol, polyvinyl pyrrolodone, ethylene diamine condensed with ethylene or propylene oxide, ethoxylated polyamines, or ethoxylated amine polymers.

Buffer:

It has been experimentally established that particularly advantageous results may be obtained in the process of the invention when the wash liquor additionally com¬ prises a buffer.

The buffer may suitably be a phosphate, borate, citrate, acetate, adipate, triethanola ine, monoethanolamine, diethanolamine, carbonate (especially alkali metal or alkaline earth metal, in particular sodium or potassium carbonate, or ammonium and HC1 salts) , diamine, especially diaminoethane, imidazole, or amino acid buf¬ fer.

Dispersing agent:

Likewise, it has been experimentally established that particularly favourable results may be obtained in the process of the invention when the wash liquor addi¬ tionally comprises a dispersing agent.

The dispersing agent may suitably be selected from nonionic, anionic, cationic, ampholytic or zwitterionic surfactants. More specifically, the dispersing agent may be selected from carboxymethylcellulose, hydroxypropylcellulose, alkyl aryl sulphonates, long- chain alcohol sulphates (primary and secondary alkyl sulphates) , sulphonated olefins, sulphated monoglycerides, sulphated ethers, sulphosuccinates. sulphonated methyl ethers, alkane sulphonates, phosphate esters, alkyl isethionates, acyl sarcosides, alkyl taurides, fluorosurfactants, fatty alcohol and alkylphenol condensates, fatty acid condensates, conden¬ sates of ethylene oxide with an amine, condensates of ethylene oxide with an amide, sucrose esters, sorbitan esters, alkyloamides, fatty amine oxides, ethoxylated monoamines, ethoxylated dia ines, alcohol ethoxylate and mixtures thereof.

The invention is illustrated in further detail in the following examples.

EXAMPLES

Example 1

3.6 kg of denim fabric and 40 g of a H. insolens 43 kD cellulase preparation (222 ECU*/g) were added to 40 1 of water and machine-washed at pH 7 and 55°C for 2 hours. The washing liquor from this treatment containing dye corresponding to an OD at 680 nm of 1.8 was used in the following experiment.

The experiment was carried out under the following con¬ ditions:

Temperature: 55"C Time: 3 hours Fabric: 4 swatches (approx. 3 x 3 cm) of white mercerized 100% cotton per beaker

Polymer: bovine serum albumin Liquid: 120 ml

The swatches were then rinsed in deionized water and air dried. Remission from the white fabric was measured at 660 nm on an Elrepho-photometer.

The results are shown in Table 1 below (average of 4 measurements) .

Table 1

Protein mg/1 Remission Δ R

Reference swatch _^ 88.75 0

0 62.54 -26.2

15 67.01 -21.7

Backstained 80 68.85 -19.9 swatches 160 70.3 -18.5

420 74,15 -14.6

840 72.7 -16.1

It appears from the table that backstaining is minimized at a protein concentration of 420 mg/1. Under these conditions, delta R is reduced by 44% compared to the reference white cotton swatch.

(*The cellulase activity is determined as the viscosity decrease of a solution of carboxymethyl cellulose (CMC) after incubation with the enzyme under the following conditions:

A substrate solution is prepared, containing 35 g/1 CMC (Hercules 7 LFD) in 0.1 M tris buffer at pH 9.0. The enzyme sample to be analyzed is dissolved in the same buffer.

10 ml substrate solution and 0.5 ml enzyme solution are mixed and transferred to a viscosimeter (e.g. Haake VT 181, NV sensor, 181 rpm) , thermostated at 40°C.

Viscosity readings are taken as soon as possible after mixing and again 30 minutes later. The amount of enzyme that reduces the viscosity by one half under these con¬ ditions is defined as 1 ECU.)

Example 2

The experimental set-up was as described in Example 1. The proteins used in this example were soy protein, pea protein and casein.

Significantly positive effects on the deposition of dye on the cotton swatches were observed for all the pro¬ teins at protein concentrations between 40 and 500 mg/1. The remission of light at 660 nm was thus significantly increased.

Example 3

The experimental set-up was as described in Example 1 with the exception that the temperature at which the polymer incubation was carried out was changed.

The experiments were carried out under the following conditions:

Temperature: 20, 30 and 40°C Time: 120 minutes Fabric: 4 swatches (approx. 5 x 5 cm) of white mercerized 100% cotton per beaker Polymer: 1.0 g/1 of lignosulphonate (sodium salt) Liquid: 100 ml

After incubation the swatches were rinsed in deionised water and air dried. Blank experiments with no polymer added were used as controls. In all cases, the lignosulphonate-treated samples showed a visible reduction in the extent of deposition of dye on the swatches compared to the controls.

Example 4

If the polymeric agent exhibits a limited surface activ¬ ity in itself (as is the case with, e.g., polyvinyl pyrrolidone) , the effect may be enhanced by adding a suitable surfactant.

The experimental set-up was as described in Example 1.

The experiments were carried out under the following conditions:

Temperature: 55°C

Time: 150 minutes

Fabric: 4 swatches (approx. 3 x 3 cm) of white mercerized 100% cotton per beaker

Polymer: 0.1 g/1 lignosulphonate (sodium salt) or

0.1 g/1 polyethylene glycol (PEG 6000) or 0.1 g/1 polyvinyl pyrrolidone (PVP

K25)

Surfactant: 0.1 g/1 non-ionic alcohol ethoxylate

Liquid: 120 ml

After incubation the swatches were rinsed in deionised water and air dried. Blank experiments with no polymer added (with or without surfactant) were used as con¬ trols.

The surfactant alone was able, to some extent, to reduce the level of dye deposition on the swatches. However, the level of dye deposition also varied with the type of polymer added. The lowest level of dye deposition was obtained with polyvinyl pyrrolidone together with surfactant.

Example 5

The effect of lignosulfonate on backstaining

The experiment was carried out in a Launder-O-meter under the following conditions(the amounts are per beaker) :

Temperature: 55°C

Time: 2 hours

Fabric: 5 g denim

2 swatches (approx. 5 x 5 cm) of white mercerized 100% cotton Liquid: Phosphate buffer pH 7, 150ml

Enzyme: 130 ECU* of a H.insolens 43 kD cellulase. Polymer: Lignosit (a lignosulfonate)

The liquor from this treatment was filtered on a filter. The filter was dried and weighed in order to measure the amount of lint formed during the wash as a measure for the abrasion of the denim fabric.

The white swatches were rinsed in deionized water after the wash and air dried, and the remission from the fab¬ ric was measured at 420nm on a Elrepho-photometer.

The results are shown in the following table (average of three beakers) : Lignosit mg lint Remission delta R g 420nm reference 0 48,2 69,3 0

+ enzyme 0 83,5 67,5 -1,8

+ enzyme 0,3 98,8 68,9 -0,4

From the results it can be concluded that, as compared to the treatment with enzyme but without Lignosit, the addition of Lignosit reduces the backstaining signifi¬ cantly even though more lint is formed.

*: Determination of the cellulolytic activity, measured in terms of ECU, may be determined according to the analysis method AF 301.1 which is available from the Applicant upon request.

The ECU assay quantifies the amount of catalytic activ¬ ity present in the sample by measuring the ability of the sample to reduce the viscosity of a solution of carboxy-methylcellulose (CMC) . The assay is carried out at 40°C, pH 7.5 using a relative enzyme standard for reducing the viscosity of the CMC substrate.

Example 6

Protein as backstaining reducing agent

The experiments was carried out in a washing machine Wascator FL 120 as follows:

3.2 kg of denim fabric (2 pair of Ball jeans and 2 Swift legs plus some previously washed denim) and 40 g of a Humicola insolens 43 kD cellulase preparation (200 ECU/g, see example 5 regarding ECU) were added to 40 1 of water and machine-washed at pH 6.6 and 55°C for 2 hours.

Egg albumin and whey protein, respectively were tested. A dosage of 8.5 g per trial (a wash in 40 1 of water) was used.

Four trials were carried out:

Test No. Protein

572 Egg albumin

576 Whey

570 Standard (no addition of protein)

577 Standard (no addition of protein)

The jeans were evaluated by a panel (6 persons named A, B, C, D, E, F) . Apart from the two jeans treated with protein two standard jeans were also evaluated in order to test if the protein had a reducing effect on the backstaining level.

Panel score A B C D E F

Line of de¬ 577/ 570 577 576 577 570 creas¬ 570 577 570 577 576 576 ing 576 576 576 570 570 577 back¬ 572 572 572 572 572 572 stain¬ ing

All panel participants agree that 572 (egg albumin) is the less backstained.

50% agree that 576 (whey) is the second less back¬ stained.

80% agree that a standard is the most backstained. From the panel test it appears that egg albumin has a reducing effect on backstaining. 50% agree that also whey has a recuding effect on the backstaining compared to a standard.

Claims

1. A process for providing improved localised variation in the colour density of the surface of dyed fabrics, the process comprising treating a dyed fabric with a cellulytic enzyme in an aqueous liquor comprising a polymeric agent.

2. A process according to claim 1, wherein the cellulytic enzyme is a fungal or bacterial cellulase.

3. A process according to claim 2, wherin the cellulase is an acid cellulase.

4. A process according to claim 3, wherein the acid cellulase is one derivable from a strain of Trichoderma. Irpex. Clostridium or Thermocellum.

5. A process according to claim 2, wherein the cellulase is a neutral or alkaline cellulase.

6. A process according to claim 5, wherein the cellulase is one derivable from a strain of Humicola. Fusarium. Bacillus. Cellulomonas. Pseudomonas. Mvceliophthora or Phanerochaete

7. A process according to claim 1, wherein the polymeric agent is one which is capable of either adsorbing to the fabric or solubilising the dye.

8. A process according to claim 7, wherein the polymeric agent is selected from proteins, protein hydrolysates, polypeptides, lignosulfonates, polysaccharides and derivatives thereof, polyethylene glycol, polypropylene glycol, ethylene diamine condensed with ethylene or propylene oxide, ethoxylated polyamines, or ethoxylated amine polymers.

9. A process according to any of claims 1-8, wherein the liquor additionally comprises a buffer.

10. A process according to claim 9, wherein the buffer is a phosphate, borate, citrate, acetate, adipate, tri- ethanolamine, monoethanola ine, diethanolamine, carbon¬ ate (especially alkali metal or alkaline earth metal, in particular sodium or potassium carbonate, or ammonium and HC1 salts) , diamine, especially diaminoethane, imidazole, or amino acid buffer.

11. A process according to any of claims 1-10, wherein the liquor additionally comprises a dispersing agent.

12. A process according to claim 11, wherein the dis¬ persing agent is selected from nonionic, anionic, cat- ionic, ampholytic or zwitterionic surfactants.

13. A process according to claim 12, wherein the dis- persing agent is selected from carboxymethylcellulose, hydroxypropylcellulose, alkyl aryl sulphonates, long- chain alcohol sulphates (primary and secondary alkyl sulphates) , sulphonated olefins, sulphated ono- glycerides, sulphated ethers, sulphosuccinates, sul- phonated methyl ethers, alkane sulphonates, phosphate esters, alkyl isethionates, acyl sarcosides, alkyl taurides, fluorosurfactants, fatty alcohol and alkyl- phenol condensates, fatty acid condensates, condensates of ethylene oxide with an amine, condensates of ethylene oxide with an amide, sucrose esters, sorbitan esters, alkyloamides, fatty amine oxides, ethoxylated mono- amines, ethoxylated diamines, and mixtures thereof.

14. A process according to any of claims 1-13, wherein the fabric is a cellulosic fabric.

15. A process according to claim 14, wherein the fabric is denim.

16. A process according to claim 14, wherein the fabric is dyed with a vat dye, direct dye, sulphur dye or reac- tive dye.

17. A process according to claim 1, wherein the concen¬ tration of the polymeric agent is between 0.1 mg/1 and 2 g/1.