EP0452393B1 - Process for heterogenously prefading items made of dyed cotton - Google Patents

Abstract

Process for heterogenously prefading items made of dyed cotton in an aqueous medium. Said items are contacted with an aqueous compound based on cellulases with or without pumice stone or amylases at a concentration, temperature and pH such as to produce a heterogenous prefading lower than 6 and preferably comprised between 4 and 5. The invention also relates to the items produced by said process.

Description

The present invention relates to a heterogeneous washing process in an aqueous medium of articles based on dyed cotton.

The repeated washing of cotton fabrics leads to a fading of colors to give a faded appearance which in some cases can be sought. For example, clothes such as pants (blue jeans), shirts, jackets, coats ... made with denim canvas are most often sold after aging by more or less thorough washing.

The current trends in the clothing market are in fact more particularly interested in a heterogeneous wash intended to reveal areas exhibiting more or less marked differences in coloration on the articles (clothing, clothing accessories such as bags, belts, etc.). .).

Currently, two techniques make it possible to obtain this heterogeneous washout aspect, but both have major drawbacks.

One of these methods is stone-washed, the other is snow-washed. In both cases, the heterogeneity of the washing is obtained in a machine drum by adding in large quantities a specific, white, light and brittle stone of volcanic origin to the articles to be discolored. The alternating rotation of the drum causes friction between the stones and the articles responsible for the greater removal of the dyes in preferential places such as the thickest parts of these articles. The stonewashing aspect is obtained by the action of stones in an aqueous medium, in the presence or not of bleaching chemicals depending on the degree of discoloration desired, at preferred temperatures of 20 to 70 ° C., while the stonewashing aspect snow is generally obtained by rubbing stones soaked in sodium hypochlorite or other powerful whitening agent, dry and at room temperature.

These washing methods have, in fact, numerous drawbacks linked to the duration of the processes when the stones are used without chemical additives or else to the toxicity of the bleaching agents which when used must be used at high concentrations for a significant washout in one operation. Finally, other drawbacks are found in the very nature of the stones which lead to extremely rapid wear of the machines and lead to a continuous clogging of the pipes for collecting the discharge water due to high loads of pumice dust.

Furthermore, these two methods cannot be used to wash articles made in part with pieces of cotton, animal skins or other fragile textiles. Indeed, the repeated rubbing of the stones on these parts would cause excessive wear of these.

The observation made by the inventors that a thorough treatment of cotton fabrics with cellulases led to a partial release of the dyes used for dyeing cellulose fibers (cotton is a natural crystalline cellulose) is the basis of the present invention .

It is important to realize that this color loss effect is exactly the opposite of that sought by the use of cellulases in commercial detergents or brightening compositions as mentioned for example in the applications for European patents (publication n ° 0 270 974, 0 269 977 corresponding to European patent n ° 0 220 016) or another example in the technical sheet of Celluzyme ™ from the Danish firm NOVO (NOVO Industrie Enzymes SA, 26 rue Fortuny, 75017 PARIS, France) aims to revive the colors of cotton items. This result is obtained by the very gentle action of cellulases which remove the microfibrils of the cotton fibers caused by wearing the garment and washing, thus restoring the original structure of the cotton fiber.

For this last application, one of the conditions of the color enhancement is that no loss of dye accompanies the action of the cellulases during the washing, while a very significant release of the dye is an essential condition for the application of the cellulases in the present invention.

The aim sought by the addition of cellulases in detergents is to restore new appearance to aged clothing in use, while on the contrary that sought for cellulases in the present invention is to cause artificial aging of new articles. in cotton.

These completely opposite aims, one of which is the basis of the present invention, are achieved with low cellulase concentrations in the case of used cotton articles to be revitalized and high in the case of new cotton articles to be aged.

A use of cellulases to introduce variations in color density into colored cotton articles has been suggested in US Patent No. 4,832,864 and the corresponding application EP-A-307564. In this patent, it is suggested that the heterogeneous washing of denim fabric clothing is obtained by the action of cellulases operating in pH zones ranging from 6.5 to 10, preferably from 6.5 to 8. These neutral or basic cellulases may be from all origins (United States patent no. 4832864) and only of fungal origin in the case of the European patent application (EP-A-307,564).

The object of the present invention is to provide a new method of washing articles made with fabrics made only of dyed cotton or based on dyed cotton associated with other textile fibers characterized in that said articles are brought into contact with '' an aqueous composition based on acid cellulases at a concentration of between 0.01 and 5 filter paper units per gram of dry tissue, at a pH below 6 and preferably between 4 and 5 and at a temperature ensuring heterogeneous washing rapid, whether or not pumice stones or amylases are present.

This method, according to the invention, has several advantages, inter alia, of being compatible with the machines used for stonewashing, does not require a new reinvestment of the users in a new material, considerably increasing the longevity of these machines, to significantly simplify the tasks of the personnel assigned to these washing operations and finally to limit the problem of pollution of discharged water.

This process of heterogeneous washing of articles, based on dyed cotton, therefore requires the action of acid cellulases placed in their optimal conditions of activity on the cellulose fibers, to release the dye bound in covalent bond with glucose units or simply fixed by various interactions.

According to the process of the invention, the cellulases, enzymes of microbial origin, are added to the washing water in which the articles based on dyed cotton are immersed and reacted with rotary stirring for a short time at their optimum temperature and pH condition, the latter being less than 6 and preferably between 4 and 5. This is in fact the functional pH of most of the cellulases which can be used according to the invention.

Such a pH also makes it possible to avoid the resolubilization of certain dyes such as indigo. Following this washing step, a final acid wash can be carried out.

Cellulases are then destroyed by the simple or combined action of proteases, temperature, extreme pH and detergents.

The effect of cellulases on cotton dyed to release color, which is the basis of the present invention, is probably explained by a controlled hydrolysis action of the least crystalline cellulose of the cotton fiber, that which was also the most susceptible to dye fixation. As a result, for a given commercial cellulase, the concentration of enzymes necessary to obtain the desired washing effect is a function of the activity of this cellulase on native cellulose. In fact, the effectiveness of these cellulase preparations for hydrolyzing cotton under the optimum pH and temperature conditions specific to each of them varies considerably. These differences in efficacy are explained by the fact that the most active cellulasic preparations contain both endoglucanase and exoglucanase activities while the least active contain endoglucanase activities. It has been found that the cellulase activity of a given cellulase, measured with filter paper as a substrate according to the method described by MANDELS M., ANDREOTTI R. and ROCHE C. (Biotechnol. Bioeng. Symp. No6, 21-33 , 1976) corresponded best with the ability of this cellulase to wash cotton denim.

In fact, it is possible to use according to the invention a wide variety of cellulases of fungal origin or of bacterial origin. cellulases can be chosen in particular from those originating from the fungi Trichoderma reesei , Penicillium funiculosum , Humicola insolens and from various bacteria in particular, Cellulomonase firmi and Clostridium thermocellum .

As will be illustrated in Examples 2, 3 and 4 below, the heterogeneous washing is obtained in industrial washing machines of different types in aqueous medium with cellulases in the absence of pumice stones. However, cellulases can also be used as a stonewash activator according to at least two possible alternatives. The cellulases are added to the aqueous media containing the articles to be washed and the usual amounts of stones, which results in a reduction of half or more of the time necessary to obtain the result of the process without the addition of enzymes. The other possibility consists in adding the cellulases in an aqueous medium containing the articles to be washed out in the presence of stones but in greatly reduced quantities. In this case, the time of the washing operation is generally not reduced compared to the usual process with stones, the benefit being a lower consumption of the stones.

In the context of the present invention, Trichoderma reesei cellulases must be used in the ratio of 0.5 to 4 filter paper units per gram of items to be washed by dry weight, depending on the texture of the fabric to obtain the best result and washing conditions (presence or absence of stones). A higher concentration is only justified when the reaction time must be reduced, a concentration below this range requires incubation times that are far too long for rational industrial exploitation. With regard to the other cellulases of bacterial and fungal origin, the most suitable concentrations of each of them are found in a significantly wider range of 0.01 to 5 units of filter paper per gram of dry article.

The action of cellulases is facilitated by a preliminary treatment of the raw articles with amylases to remove the starch finish and by the association with cationic, anionic or non-anionic detergents compatible with a given cellulase and with dispersing substances. and indigo antireposition in the case of very dark denim fabrics.

Another important aspect of the invention resides in the simultaneous use of amylases, enzymes for degrading starch and cellulases to carry out the deaerating and the washing in a single operation. The simultaneous action of the two types of enzymes allows a simplification and a saving of time for the process implemented to obtain a faded article from the raw garment after making.

The optimal pH and temperature conditions used during the reaction of the cellulases with the articles to be bleached may depend on the enzyme used but are usually a pH between 4 and 5, preferably between 4.5 and 4.8 and a temperature of the order of 60 ° C. The reaction time is approximately 1 hour.

The present invention generally relates to clothing or other manufactured articles made from dyed cotton fabrics which have been washed in a heterogeneous manner according to the invention.

The examples below, given without implied limitation, will make it possible to demonstrate other advantages and characteristics of the invention.

Example 1

Three denim fabric garments were purchased from a clothing store. The first was a denim canvas skirt, the second was a 501 blue jean by LEVI STRAUSS and the third was a blue jean in stretch fabric made of 98% cotton and 2% elastane Lycra. These three garments had been softened and shrunk by a simple wash. The same three types of stone washed clothing were also purchased to facilitate comparison with the first three items subject to the following processing:

The three items of clothing were placed in a household washing machine with front window (Miele Model W730). After putting in water and rotating the drum for 5 min. the machine is stopped, the pH of the water in the drum is brought to a value of 4.6-4.8 (measured with a pH indicator paper) with 10 ml of 100% acetic acid. Then 20 ml of a solution of CAYLASE 345 at 1.2 x 10⁵ filter paper units per liter are added to the water (CAYLASE 345 is a cellulase from Trichoderma reesei sold by the company CAYLA). The enzyme concentration in this example is 2400 filter paper units for 1.7 kg of clothing. The machine is restarted with a program of 60 minutes of alternating rotation of the drum with maintaining the water at 60 ° C followed by the emptying of the water which has turned dark blue and filling again. The machine is stopped and the pH of the new water is brought to 11 with 10 ml of concentrated sodium hydroxide. The machine is restarted with a program of 15 minutes of rotation at 60 ° C, emptying of the water again turned dark blue, rinsing, 2 washes, rinsing and spinning. The three garments after drying in a rotary household tumble dryer (Philips, Model AMB508) are compared with the three equivalent garments washed in stones (stone-washed) purchased at the store.

The three garments have a characteristic aspect of stonewashing (more pronounced lightening at the level of belts, pockets and seams) with a brighter shine compared to the same stonewashed articles.

Example 2

40 ml of Celluclast 1.5 L (Novo) (cellulases containing 9.10⁴ filter paper units / liter) are added to the water heated to 60 ° C. and brought to pH 4.5 with acetic acid, of a household washing machine (MIELE W730). Two coats in raw Denim canvas, one with a collar in non-denim cotton fabric are introduced into the machine. The jacket made with a collar in non-denim cotton fabric, cannot be washed by the stone method due to the fragility of this fabric to abrasion by pumice stones. After 60 min. walking with water regulation at 60 ° C, the water is drained and 500 ml of sodium hypochlorite at 12 ° Cl are added to the new water. After 15 min of rotation of the cold drum, the water is drained and washing with household detergent for 15 min. at 60 ° C is followed by emptying, two rinses and spinning.

The two jackets have an aged appearance of the best effect, identical for the two garments and a perfect collar for the jacket whose collar was made with a fragile cotton fabric.

Example 3

60 raw canvas blue jeans are distributed in the two compartments of a used machine industrially for stonewashing (ATENOX, St Médars en Jalles, France) containing approximately 500 liters of water. The temperature rose to 70 ° C by steam and the drum was rotated for 15 min. The blue water is discharged and replaced by the same volume of water. The pH is lowered to 4.5-4.8 with 500 ml of concentrated acetic acid and 1.5 l of Celluclast 1.5 L (9 x 10⁴ units of filter paper / liter) (Novo) are distributed in the two compartments . The concentration of enzymes in this example is 1.3 x 10⁵ units of filter paper per 36 kg of pants. The water temperature is brought to 60 ° C and the drum rotated for 45 min. The dark blue water is discharged and the compartments are refilled with water brought to 60 ° C. and to which 1 kg of detergent without bleaching agent (Henkel) is added to give a pH of approximately 11.5. After 15 min. rotation, emptying is followed by two washes with clear water for 5 min. then spin and dry.

The appearance of the blue jeans was similar to that of pants of the same series washed in the same machine containing pumice stones, with however an improvement by an almost total absence of white mottling and a greater contrast of the white and blue colors.

Example 4

120 pants in raw denim fabric, thicker than in Example 2, are distributed in the two compartments of an industrial washing machine (MILNOR, New Orleans, United States). The pH of the 500 liters of water is brought to 4.5-4.8 with 700 ml of acetic acid and after addition of 3 liters of CAYLASE P to 150 g / l of protein (1.35 x 10⁵ units of filter paper per liter). CAYLASE P is an enzyme preparation of Penicillium funiculosum containing cellulases and amylases, marketed by CAYLA), the temperature is brought to 60 ° C. After 10 minutes of rotation, 200 ml of acetic acid are added to bring the pH down to 4.5-4.8 and the washing is continued for 50 min. The dark blue water is drained, and 500 ml of liquid detergent containing proteases (ARIEL) are added to the new water. After 15 minutes of rotation at 60 ° C. the rinsing operation is followed by two washes, a spin and drying.

The quality of the washing of the clothes in this example was also higher than that of the pants of the same series washed by the stone method.

Example 5

An ATENOX machine is loaded with 60 kg of raw jeans and 120 kg of pumice stone filled with approximately 500 liters of water heated to 60 ° C with steam. The drum is rotated and 1 liter of CAYLASE 345 (2.4 x 10⁴ filter paper units per liter) is added after the pH of the hot water has been adjusted to about 5 with 800 ml of acetic acid. After 30 minutes the water is drained without the stones, the machine is refilled with 500 liters of water and the drum is returned to spin for 30 min. The water is drained and then washed with 2 kg of industrial detergent for 15 min. with cold water is followed by 2 rinses of 5 minutes. the pants are removed from the machine, removed from the stones in the pockets, wrung out and dried.

Under these conditions, the pants had a deep stone-washed appearance identical to those washed out by the same event sequences without the addition of enzyme. The addition of the enzymes resulted in this example in time savings of 90 minutes out of a total of 3 hours for the proceeded only with stones.

Example 6

A Milnor industrial washing machine is loaded with 60 casual jeans. Two kilograms of the powder mixture of the following composition: 100 g monosodium orthophosphate, 100 g sodium acid pyrophosphate, 450 g sodium sulfate, 300 g Celluzyme ™ (NOVO), 50 g cationic surfactant, are added to the 500 liters of water brought to 50 ° C. After an hour of walking, the water is drained and then washed for 15 min. at 60 ° C with an industrial perborated detergent (St Marc) is followed by two rinses of 5 minutes in cold water and spinning.

After drying, the pants presented a sought-after appearance characterized by a marked contrast between the white and blue parts.

Claims (9)

1. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium, characterised in that the said articles are brought into contact with an aqueous composition based on acid cellulases at a concentration of between 0.01 and 5 filter paper units per gram of dry fabric, with a ph of less than 6 and preferably between 4 and 5 and at a temperature ensuring rapid heterogeneous washing out of colour.
2. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to Claim 1, characterised in that the said articles are also brought into contact with pumice stones.
3. Process for heterogeneously washing the colour out of articles based on dyed cotton in a aqueous medium according to Claim 1, characterised in that the aqueous composition also comprises amylases.
4. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to Claim 1, 2 or 3, characterised in that the cellulases are added at a high concentration to the washing water in which the fabrics are steeped, optionally in the presence of pumice stones or amylases, and caused to react under their optimum ph and temperature conditions and under rotary agitation for a short time, and in that, after the colour has been heterogeneously removed from the said fabrics, the cellulases are eliminated by the single or combined action of proteases, temperature, extreme ph values and detergents.
5. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to one of Claims 1, 2, 3 and 4, characterised in that the cellulases used have an optimum ph of less than 6 and are fungal or bacterial in origin.
6. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to one of Claims 1, 2, 3 and 4, characterised in that the cellulases are chosen from amongst Trichoderma, Penicillium or Humicola cellulases.
7. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to one of Claims 1 to 5, characterised in that the Trichoderma reesei cellulases are used at a ph of less than 6 and at temperatures of between 50 and 65°.
8. Process for heterogeneously washing the colour out of articles based on dyed cotton in an aqueous medium according to one of Claims 1 to 7, characterised in that anionic, cationic or non-ionic detergents compatible with the type of enzyme used are associated with the said cellulases.
9. Articles based on dyed cotton with their colour washed out heterogeneously in an aqueous medium, characterised in that they are obtained by the implementation of the process according to one of Claims 1 to 8.