GB2136029A - Process for treatment of denim and other fabrics - Google Patents

Abstract

Denim and other cotton fabrics are given a worn or "stone washed" look by washing in dilute aqueous alkali.

Description

SPECIFICATION Process for treatment of denim and other fabrics This invention relates to a process for the treatment of denim and other cotton fabrics, to give them a used or worn look.

Acurrentfashion isforso-called "stone-washed" denim, i.e., denim which has been washed of tumbled with water along with either natural pumice or synthetic stones, which give the otherwise new denim a worn or used appearance. The use of such stones to give this appearance is, of course, highly detrimental to the apparatus used in this treatment, this usually being a conventional washing machine ofthe rotating drum type.Additional disadvantages are damage to dryers used inthesubsequentdrying of the stone washed fabric due to stones not removed from the fabric afterthe washing process; the presence of dust or grit in the dried fabric, particularly in the pockets and seams and folds of premadearticlesthat are subjectto this treatment; and the time factor required in loading and unloading the machines and separating the washed fabric from the stones prior to drying. Also the stone wash treatment is or can be uneven with excessive wear, ortheformation of actual holes or tears, in excess if the required worn look, in localised regions of the treated fabric.

In accordance with the present invention it has been discovered that essentially the same appearance can be obtained simply by washing thefabric in dilute alkali, particularly, but not exclusively dilute sodium or potassium hydroxide. Accordingly the present invention provides a process for the treatment of denim and other cotton fabrics to give them a used or worn appearance which comprises washing the fabric in a dilute aqueous alkaline solution, preferably a sodium or potassium hydroxide solution.

The treatment ofthe invention may be applied to any cotton fabric, including 100% cottons and cotton synthetic blends, e.g. cotton/polyamide and cotton/ polyester blends.

After washing with the dilute alkali, the fabric is preferably rinsed first in fresh waterto remove excess alkali and then soured in a dilute acid solution, e.g.

dilute acetic acid,to bring the pH to a neutral or slightly acid level. Following this souring rinse the fabric is treated with the usual fabric conditioners in a final rinse and then dried.

In the alkali washing step characteristic of this invention suitable amounts of alkali can be provided by adding to the aqueous wash medium from 1-6% by wt of alkali based on the total weight of the wash liquid; i.e. 10-60 g.p.l., preferably 10-30 g.p.l. Although sodium hydroxide is cheaper, potassium hydroxide is preferred because of its greater stability and ease of handling and storage. The temperature of the alkali wash is in no way critical and temperatures from ambient to boiling can be used. Other alkaline materials suitable for use in the invention include, in particular, alkali metal silicates and phosphates.

Priortothe alkali wash thefabric may be given a conventional desizing treatment, e.g. a prewash, and/or bleached, although, if desired, the bleaching step can be carried out afterthe dilute alkali wash. In addtion fabric softeners may be added to the treat ment solutions at any stage, but most preferably during the acid conditioning orfinal rinse stage. The use of such fabric softeners is traditional in the laundry art and, as such, does notform partofthe present invention.

The treatment in accordance with this invention can be applied to eitherthe bulk fabric, orto the finished goods, orat any intermediate stage in the production.

Thefollowing example illustrates the technique of the present invention.

EXAMPLE Denim fabric in made up form as jeans was first desized by conventional washing in water at a temperature 50-70 C; Following the desizing wash potassium hydroxide was added to the wash liquor as an aqueous concentrated solution sufficientto provide an alkali hydroxide concentration in the wash liquor of about 22.5 g.p.l. and washing continued at 46-65"C for 15-30 minutes. Atthe end ofthe alkali wash, the fabric was drained, rinsed with fresh water and soured by rinsing in a dilute acetic acid solution.

The soured fabric was then given a conditioning rinse with a conventional fabric conditioner, and finally dried. The product denim fabric treated in this manner has a distinctly worn or used looksimilarto that produced in the art by stone washing.

1. Amethodoftreating neworunuseddenimor other cotton-containing fabric to give the fabric an artificially created used or worn look which comprises washing the fabric in dilute aqueous alklali.

2. A method according to claim 1,whereinthe dilute aqueous alkali is dilute aqueous sodium or potassium hydroxide.

3. A method according to claim 1 or 2, wherein the fabric is given a souring treatment after the alkali wash.

4. A method according to claim 3, wherein the fabric is soured by rinsing in an aqueous acetic solution.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Process for treatment of denim and other fabrics This invention relates to a process for the treatment of denim and other cotton fabrics, to give them a used or worn look. Acurrentfashion isforso-called "stone-washed" denim, i.e., denim which has been washed of tumbled with water along with either natural pumice or synthetic stones, which give the otherwise new denim a worn or used appearance. The use of such stones to give this appearance is, of course, highly detrimental to the apparatus used in this treatment, this usually being a conventional washing machine ofthe rotating drum type.Additional disadvantages are damage to dryers used inthesubsequentdrying of the stone washed fabric due to stones not removed from the fabric afterthe washing process; the presence of dust or grit in the dried fabric, particularly in the pockets and seams and folds of premadearticlesthat are subjectto this treatment; and the time factor required in loading and unloading the machines and separating the washed fabric from the stones prior to drying. Also the stone wash treatment is or can be uneven with excessive wear, ortheformation of actual holes or tears, in excess if the required worn look, in localised regions of the treated fabric. In accordance with the present invention it has been discovered that essentially the same appearance can be obtained simply by washing thefabric in dilute alkali, particularly, but not exclusively dilute sodium or potassium hydroxide. Accordingly the present invention provides a process for the treatment of denim and other cotton fabrics to give them a used or worn appearance which comprises washing the fabric in a dilute aqueous alkaline solution, preferably a sodium or potassium hydroxide solution. The treatment ofthe invention may be applied to any cotton fabric, including 100% cottons and cotton synthetic blends, e.g. cotton/polyamide and cotton/ polyester blends. After washing with the dilute alkali, the fabric is preferably rinsed first in fresh waterto remove excess alkali and then soured in a dilute acid solution, e.g. dilute acetic acid,to bring the pH to a neutral or slightly acid level. Following this souring rinse the fabric is treated with the usual fabric conditioners in a final rinse and then dried. In the alkali washing step characteristic of this invention suitable amounts of alkali can be provided by adding to the aqueous wash medium from 1-6% by wt of alkali based on the total weight of the wash liquid; i.e. 10-60 g.p.l., preferably 10-30 g.p.l. Although sodium hydroxide is cheaper, potassium hydroxide is preferred because of its greater stability and ease of handling and storage. The temperature of the alkali wash is in no way critical and temperatures from ambient to boiling can be used. Other alkaline materials suitable for use in the invention include, in particular, alkali metal silicates and phosphates. Priortothe alkali wash thefabric may be given a conventional desizing treatment, e.g. a prewash, and/or bleached, although, if desired, the bleaching step can be carried out afterthe dilute alkali wash. In addtion fabric softeners may be added to the treat ment solutions at any stage, but most preferably during the acid conditioning orfinal rinse stage. The use of such fabric softeners is traditional in the laundry art and, as such, does notform partofthe present invention. The treatment in accordance with this invention can be applied to eitherthe bulk fabric, orto the finished goods, orat any intermediate stage in the production. Thefollowing example illustrates the technique of the present invention. EXAMPLE Denim fabric in made up form as jeans was first desized by conventional washing in water at a temperature 50-70 C; Following the desizing wash potassium hydroxide was added to the wash liquor as an aqueous concentrated solution sufficientto provide an alkali hydroxide concentration in the wash liquor of about 22.5 g.p.l. and washing continued at 46-65"C for 15-30 minutes. Atthe end ofthe alkali wash, the fabric was drained, rinsed with fresh water and soured by rinsing in a dilute acetic acid solution. The soured fabric was then given a conditioning rinse with a conventional fabric conditioner, and finally dried. The product denim fabric treated in this manner has a distinctly worn or used looksimilarto that produced in the art by stone washing. CLAIMS

1. Amethodoftreating neworunuseddenimor other cotton-containing fabric to give the fabric an artificially created used or worn look which comprises washing the fabric in dilute aqueous alklali.

2. A method according to claim 1,whereinthe dilute aqueous alkali is dilute aqueous sodium or potassium hydroxide.

3. A method according to claim 1 or 2, wherein the fabric is given a souring treatment after the alkali wash.

4. A method according to claim 3, wherein the fabric is soured by rinsing in an aqueous acetic solution.