EP0377417A1

EP0377417A1 - A system for decolouring denim fabric by means of high pressure and high temperature water jets

Info

Publication number: EP0377417A1
Application number: EP89830562A
Authority: EP
Inventors: Paolo Cingolani
Original assignee: Cinpas Di Pastuglia Franca & C-Snc
Current assignee: Cinpas Di Pastuglia Franca & C-Snc
Priority date: 1988-12-29
Filing date: 1989-12-21
Publication date: 1990-07-11
Also published as: IT8800649A0; IT1237368B

Abstract

This invention relates to a procedure for decolorizing denim by spraying a jet of preheated water under pressure (with the possible addition of chemical compounds) on a section of this fabric kept perfectly and uniformly stretched so that the water jet may energetically pass through the fibres of the same.

Description

This design patent application relates to a procedure for decolorizing denim by means of water jets at a high pressure and temperature.
It is a well known fact that denim is still very popular in many sectors of the fashion field, above all in the field of fashion for the young; for some years now however leading clothing industries have submitted newly manufactured items, and sometimes even the fabric before it is cut, to a so-called ageing treatment, consisting in artificially decolorizing the dye, to give the impression that the manufactured item is worn.
Several years ago a procedure for decolorizing denim was developed to give the external appearance of the fabric a worn look and faded colouring.
To date the majority of procedures for decolorizing denim have involved placing the items to be treated in the rotating drum of a large industrial washing machine together with a large number of pumice stone granules and in some cases with a quantity of chemical additives in order to fade the dye of the denim.
It should in particular be noted that the above pumice stone granules, during the repeated and energetic alternating mixing of the water in the drum of the above machine, strike the items being treated repeatedly, consequently carrying out an efficient abrasive and undoubtedly decolorizing action on the fabric in which the items are manufactured.
It should however be noted that this type of treatment in fact involves various different problems due, on one hand to the high cost of the washing machines used and, on the other to the damage resulting from the use of pumice stones.
The granules of this stone at the end of the rather lengthy decolorizing operation, and consequently after repeated energetic contact with the items to be treated and with the sides of the drum, crumble until they almost pulverize and consequently the fine pumice dust which forms may settle in the pockets of the seams of the clothing items treated, or in the cracks and gaps in the drum, with the risk that some mechanical mobile parts may be worn by friction or become jammed, such as the pumps, gears or other parts.
In addition to the above it should be noted that in the previous procedures, in order to obtain different degrees of decolorizing, it was necessary to treat the clothing items in the drums for cycles of varying durations; in the case of strong decolorizing requirements it was necessary to keep the clothing items in the drum longer, to the extent that the treatment became too lengthy and often did not meet the industrial requirements of the manufacturer.
No less important was the problem of draining the liquid containing the pulverized pumice stone from the drum after the treatment; pumice stone is in fact highly polluting and consequently it needs to be eliminated according to specific safety procedures which are complicated and costly.
It was these very problems that the procedure according to the invention was designed to resolve since the same is not difficult to produce and makes it possible, with a few and inexpensive technical fixtures and in short operating times, to achieve the same decolorizing effect on the denim which to date was obtained only with the complicated and time consuming procedures described above.
The basic principle of the procedure according to the invention involves decolorizing the denim by means of a powerful jet of water at high pressure and at a high temperature; it should be noted in this regard that the item to be treated should be carefully ironed and stretched in front of the jet of water under pressure so that the jet may strike the item directly and uniformly, in order to energetically and easily penetrate all the fibres.
The clothing item could, above all in the case of trousers, be fitted on appropriately sized manikins which stretch the fabric of the clothing item completely and uniformly.
It is obvious that if the clothing items were simply hung from a line, a hangar or any other manikin, the same would be subject to moving under the strength of the forced jet of water or fall off, or even be decolorized in a non uniform manner by the water; the manikin on which to stretch the clothing items must therefore be selected very carefully in that only if the clothing item can be "fitted" perfectly on an appropriate manikin, can the fabric be stretched perfectly, thereby avoiding the formation of unwanted creases in which decolorizing would not be complete.
In fact it is precisely when the water is forced through the fabric that the colour tone is faded as required; in order to obtain different degrees of ageing of the fabric it is sufficient to vary the pressure and temperature of the water jet.
According to the above it is easy to appreciate the enormous advantages of the procedure according to the invention with respect to the decolorizing systems used previously; the new procedure in question can firstly be carried out without utilizing the costly machines or pumice stone used previously, thereby avoiding the problem related to eliminating the same.
Thanks to the method according to the invention it is also possible with respect to the previous technique, to reduce the procedure treatment times drastically in that, as described previously, in order to obtain a higher degree of decolorization, it is not necessary to lengthen the treatment time as in the case of the previous procedures, but simply to increase the pressure and the temperature of the jet of water.
With regard to stretching the items to be treated, it should be noted that the items treated could be fitted on standard manikins even if in fact apparently the most efficient solution seems to be that of using inflatable manikins in that these can easily be adapted to the different sizes of the clothing items and can stretch the item fitted on the same by adjusting the inflation pressure.
In the case of the latter it should be noted that the pressure of the water jet which strikes a clothing item stretched on an inflatable manikin must be adjusted not only according to the decolorization requirements but also according to the inflation pressure of the manikin which would otherwise prevent the forced water from penetrating through the fibres of the clothing item being treated.
In order to make the procedure according to the invention even faster, a standard chemical additive could be added to the water in order to attack the dye of the fabric being treated.
A further advantage of the working procedure according to the invention is the fact that during the treatment, contrary to previous procedures, the decolorizing procedure can be controlled visually and can be interrupted as necessary, or continued as the case may be, until the fabric being treated is decolorized as necessary.
In order to describe the procedure more precisely and schematically, it should be noted that the same is carried out in sequence in the following operating phases:

1) the clothing item to be treated is placed on a suitably sized manikin, the same being inflatable in the preferred embodiment of the invention, so that the fabric of the clothing item may be stretched and maintained uniformly;
2) forced spraying of the clothing item to be treated by means of a water nozzle capable of emitting a jet of preheated water (with or without the addition of chemical compounds) at a high pressure capable of penetrating the fibres of the clothing item, energetically.

Finally for major clarity it should be noted that the decolorizing action of the denim may be obtained with water at a pressure varying from one to 120 atms and at a temperature varying from 20°C to 100°C; obviously the selection of the combination of a specific temperature and pressure will depend on the degree of decolorization and the operating times required for the procedure in question.

Claims

1) A procedure for decolorizing denim by means of a water jet at high pressure and at a high temperature characterized in that the same consists of the following sequence of operating phases:

a) placing the clothing item to be treated on a suitably sized manikin, the same being inflatable in the preferred embodiment of the invention, so that the fabric of the clothing item may be stretched and maintained uniformly;

b) A forced spraying of the clothing item to be treated by means of a water nozzle capable of emitting a jet of preheated water (with or without the addition of chemical compounds) at high pressure capable of penetrating the fibres of the clothing item, energetically.

2) A procedure for decolorizing denim by means of a jet of water at high pressure and at a high temperature according to the previous claim, characterized in that the water used may be of a temperature varying from 20°C to 100°C and pressure varying from 1 to 120 atms.

3) A procedure for decolorizing denim by means of a jet of water at high pressure, according to the previous claims, characterized in that suitable chemical compounds capable of shortening the decolorizing procedure time in question, may be added to the water used may, if necessary.