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Title:
PROCESS FOR DYEING PRODUCTS OR FABRICS
Document Type and Number:
WIPO Patent Application WO/2022/162462
Kind Code:
A1
Abstract:
Process for dyeing products or fabrics, comprising the following phases: • at least one cleaning phase, wherein the product or fabric to be dyed is cleaned by means of a treatment with pressurized ozone; at least one dyeing phase, wherein the product or fabric is dyed; • at least one finishing phase for finishing the dye on the dyed product or fabric. Said at least one dyeing phase comprises a step of preparing a dyeing bath. The dyeing bath comprises: at least one natural dye of vegetable or animal origin; water at a temperature of 12°C to 20°C; at least one natural resin, preferably of tree origin, suitably dispersed in the aqueous solution; citrus fruit concentrate, suitable for use as a fixative agent; rosemary essential oil, suitable for use as an anti-fermentation and anti-oxidant agent; Indian hemp pectin, suitable for use as a suspending agent; and sodium bicarbonate.

Inventors:
ROMAGNOLI RICCARDO (IT)
Application Number:
PCT/IB2021/062344
Publication Date:
August 04, 2022
Filing Date:
December 27, 2021
Export Citation:
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Assignee:
MAKE IN ITALY SRL (IT)
International Classes:
D06P5/20; D06L4/50; D06P1/34; D06P1/46; D06P1/52; D06P1/673
Foreign References:
EP2708641A12014-03-19
CN111851090A2020-10-30
Other References:
SAMINATHAN RATNAPANDIAN ET AL: "Colouration of cotton by combining natural colourants and bio-polysaccharide", THE JOURNAL OF THE TEXTILE INSTITUTE, TAYLOR & FRANCIS, GB, vol. 104, no. 12, 1 January 2013 (2013-01-01), pages 1269 - 1276, XP001586299, ISSN: 0040-5000, [retrieved on 20130523], DOI: 10.1080/00405000.2013.797143
Attorney, Agent or Firm:
BARZANO' & ZANARDO MILANO S.P.A (IT)
Download PDF:
Claims:
CLAIMS :

1 . Process for dyeing products or fabrics , comprising the following phases :

• at least one cleaning phase , wherein the product or fabric to be dyed is cleaned by means of a treatment with pressuri zed ozone ;

• at least one dyeing phase , wherein the product or fabric is dyed;

• at least one finishing phase for finishing the dye on the dyed product or fabric ; said at least one dyeing phase comprises a step of preparing a dyeing bath; said dyeing bath comprising : at least one natural dye of vegetable or animal origin; water at a temperature of 12 ° C to 20 ° C ; at least one natural resin, preferably of tree origin, suitably dispersed in the aqueous solution; citrus fruit concentrate , suitable for use as a fixative agent ; rosemary essential oil , suitable for use as an antifermentation and anti-oxidant agent ;

Indian hemp pectin, suitable for use as a suspending agent ; and sodium bicarbonate .

2 . Dyeing process according to claim 1 , wherein the dyeing bath comprises : lemon j uice concentrate 150 parts

Indian hemp pectin 30 parts rosemary essential oil 5 parts damar resin 50 parts linseed oil 20 parts conifer resin 50 parts sodium bicarbonate 5 parts.

3. Dyeing process according to claim 2, wherein the solution thus obtained is mixed in a percentage of 4% to 12% with water; said dyeing bath is kept at a temperature of 10°C to 20°C.

4. Dyeing process according to one of the preceding claims, wherein the cleaning phase is carried out by means of a washing machine supplied exclusively with ozone gas at about 3.5 atmospheres.

5. Dyeing process according to claim 1, wherein the dyeing phase includes a step of immersing the product or fabric into the dyeing bath; said immersion step has a time duration in the range of 0.1 seconds to 1 minute, preferably 1 second.

6. Dyeing process according to claim 5, wherein the immersion step is followed by a hydro-extraction step, in which as much dyeing bath is removed from the product or fabric as possible.

7. Dyeing process according to claim 6, wherein the hydroextraction step is followed by a drying step, in which the water comprised in the dyeing bath that has remained in the products or fabrics is eliminated.

8. Dyeing process according to claim 1, wherein the cleaning phase comprises a step of inserting the product or fabric into a container; preparing at least one washing liquid by adding said ionizing substances and/or a natural detergent; executing the washing.

9. Dyeing process according to claim 1, wherein said finishing phase is carried out after the dyeing phase, said finishing phase comprising a pausing step, in which the same products or fabrics undergo no operation for a time of 24- 48 hours in order to allow the dye to be fixed on the product or fabric, followed by washing in water with acetic acid .

10 . Dyeing process according to claim 1 , wherein said finishing phase is carried out after the dyeing phase , said finishing phase comprising an oven curing step, in which the dyed products or fabrics are placed for more than 120 seconds into a curing oven at a temperature of approximately 160 ° C, followed by washing in water with acetic acid .

Barzand & Zanardo Milano S . p .A.

Description:
TITLE: PROCESS FOR DYEING PRODUCTS OR FABRICS

The present invention relates to an innovative process for dyeing products or fabrics, in particular textile fibres, yarns, fabrics and/or textile products. In particular, the present invention concerns a natural process for dyeing products or fabrics which results in a "healthy", non- allergenic and totally aseptic dyeing that can improve the colour fastness of the dyed product or fabric.

The invention follows an innovative path which may also be considered as a production specification and used for certifying the dyeing method, for the purpose of confirming the use of products that have been tested in compliance with the most severe international standards, such as the (CE) standard no. 1907/2006, commonly referred to as REACH, and the (CE) standard no. 66/2010 and (EU) standard no. 782/2013, referred to as ECOLABEL.

- PRIOR ART -

Dyeing is the process of applying colour to, or changing the colour of, materials by means of a dyeing bath in which dyes have been dissolved. Dyes can be applied to many different materials, including hide, leather and wood, but the most important field of application concerns textile fibres, yarns and fabrics.

Natural dyeing products may be of vegetable origin, e.g. flowers, leaves, roots, barks, fruits, herbs; or of animal origin, e.g. cochineal, purpura and sepia. In some cases, prior to dyeing it is necessary to prepare the textile fibres by mordanting, which makes the dye become soluble in water, letting it tenaciously penetrate the fibres. A decoction is prepared by macerating or boiling the vegetables in water . Then the fibres , previously wetted or treated with mordant , are immersed in the dyeing bath prepared with the diluted and heated decoction . Sometimes the dyeing bath does not become exhausted after the f irst immersion, and can be used as a recovered dyeing bath for subsequent dyeing operations , which will however give a dying with clearer shades compared with the previous batch . Accurate rinsing and drying will then follow . The dyeing method will vary depending on the stage of the textile manufacturing process at which dyeing occurs :

• dope dyeing, when the dye is added prior to extrusion;

• flock dyeing, when the flock is dyed prior to spinning;

• package dyeing, when the yarn is dyed on perforated cones ;

• hank dyeing, when the yarn is dyed in hanks ;

• mass dyeing;

• piece dyeing, when the fabric is dyed;

• garment dyeing, when the finished garment is dyed .

As far as natural dyeing is concerned, several problems have arisen in the methods currently known in the art . During the mordanting phase , rock alum i s normally used, which i s a mineral that is highly carcinogenic, much like asbestos and D . D . T . The dyeing processes currently known in the art are mistakenly considered as natural/vegetable dyeing methods , although mineral , and sometimes animal , products are also used in combination with industrial chemical products , thus being in contrast with health and ethical principles .

Products have been used in the past and are still in use in natural dyeing processes which, although natural , are not at all healthy for humans . The following is a list of the products that are most commonly used in natural dyeing processes according to the current state of the art, which are particularly harmful for humans: lime water (calcium oxide, an irritant) ; aqua regia, which can corrode metals such as gold; arsenic (a heavy metalloid and a well-known poison) ; white lead (lead carbonate compound) ; vitriol oil (a derivative of the well- known poison) ; potash (potassium carbonate, highly noxious) .

Current dyeing processes utilize exceedingly large quantities of water, amounting to approximately 180 times the weight of the dyed product.

With the currently known methods, colour fastness to washing is, according to principles defined by the ISO 105- C standards, very low, much below the minimum value allowed by the various national and international regulations; as an example, for dark colours it hardly reaches the absolute value of 2 over a scale of values from 1 to 5, while the minimum value required by the law is 3.

The processes currently used at industrial level envisage no sweat and saliva fastness tests. Internal tests have shown that such colour fastness is non-existent in garments dyed using traditional methods.

In the dyeing processes currently in use, it is impossible to reproduce colours with the desired shades, since they have been standardized by quantity. This aspect is particularly evident in dark shades.

Besides, an article entitled "Colouration of cotton by combining natural colourants and bio-polysaccharide" is known which was published in "THE JOURNAL OF THE TEXTILE INSTITUTE, TAYLOR & FRANCIS, GB", volume 104, no. 12 of 1 January 2013, pp . 1269 to 1276. Also , a method is known from patent application EP2708641A1 for giving colour to several materials/ substrates using compounds naturally present in nature - natural colorants , which implies contacting the material with a mixture of vegetable extracts and enzymes with oxidase , oxidoreductase or peroxidase activity in the extracts and also preferentially the pre-treatment of the material by plasma and/or ozone . Such material s/ substrates are fabrics , fibres , yarns , films or structures of natural or synthetic origin, such as : fur, leather, hide , hair, silk, wool , angora, cashmere , cotton, linen, j ute , hemp, sisal , cork, lyocell , polyamide , polyester, acetate or viscose and its mixtures . Such method is used for colouring natural and synthetic materials with natural colorants , presenting a colour with high colour fastness .

Furthermore , the currently known dyeing methods envisage no steps of cleaning the product or fabric to be dyed, so that the latter still includes all the harmful substances derived from the fabric manufacturing process . Such harmful substances are not eliminated during the conventional dyeing phase .

Lastly, a method for dyeing products or fabrics is known from Italian patent 102015000023312 which comprises the steps of cleaning and dyeing the fabric and finishing the dye on the product or fabric . The dyeing step occurs in a dyeing bath comprising at least one natural dye of vegetable origin, water at a temperature of 12 to 20 ° C, and at least one natural resin of tree origin suitably dispersed in the aqueous solution .

OBJECT OF THE INVENTION The present invention aims at providing an ef ficient process for dyeing products or fabrics in a completely natural way while increasing the colour fastness to washing of the dyed product , yarn or fabric . The dyeing proces s according to the present invention is healthy and uses only harmless products that permit increasing colour fastness to washing .

The present process can solve all the above-mentioned technical problems that may be encountered in the methods currently known in the art . The present process has a substantially null environmental impact . In the dyeing process according to the present invention, the dyeing product coats the fibres , stably adhering thereto and increasing colour fastness to washing .

For the purposes of the present description, the term dyeing product refers to the product adapted to dye the fibres of the product or fabric .

The dyeing process according to the present invention requires no mechanical forces for moving the product or fabric for a predetermined period of time , nor any physical forces , in particular high temperatures and large quantities of water and industrial chemicals , such as ammonia-based substances , for promoting the penetration of the dyeing product into the fibres .

Due to greater utili zation of a natural resin and to the use of Indian hemp pectin, the dyeing process according to the present invention makes it possible to ef fectively coat the fibre and the fabric with dye , ensuring a degree o f colour fastness even exceeding that of industrial dyeing .

Said natural resin and Indian hemp pectin are dispersed in water and used for preparing the dyeing bath . One aspect of the present invention concerns an innovative process for dyeing products , yarns or fabrics having the features set out in the appended claim 1 .

Auxiliary features are comprised in dependent claims .

The features of the process according to the present invention will now be explained in detail with reference to an exemplary, but non-limiting, embodiment thereof .

- DETAILED DESCRIPTION OF THE INVENTION -

The method according to the present invention essentially consists of a number of phases . The method for dyeing products or fabrics comprises the following three distinct phases , preferably carried out in succession : at least one cleaning phase , wherein the product or fabric to be dyed is cleaned by means of a treatment with pressuri zed ozone ; this phase is preferably carried out prior to the dyeing phase ; at least one dyeing phase , wherein the product or fabric is actually dyed; and at least one finishing phase for finishing the dye on the dyed product or fabric .

For the purposes of the present invention, the term product may refer, without distinction, to garments , yarns , fabrics , ready-made textile products , etc .

In a preferred implementation, said at least one dyeing phase comprises a step of preparing a dyeing bath . Said dyeing bath comprises : at least one natural dye of vegetable or animal origin; water at a temperature of 12 ° C to 20 ° C ; at least one natural resin, preferably of tree origin, suitably dispersed in the aqueous solution; citrus fruit concentrate , suitable for use as a fixative agent ; rosemary essential oil , suitable for use as an antifermentation and anti-oxidant agent ;

Indian hemp pectin, suitable for use as a suspending agent to keep in suspension the various components and attain colour fastness to rubbing after the drying phase ; sodium bicarbonate .

The process for dyeing products or fabrics according to the present invention makes it possible to increase colour fastness to washing .

Describing now the process more in detail , said at least one , preferably only one , cleaning phase is preferably a washing phase .

Said cleaning phase is essentially characteri zed in that the fibres of the fabric are opened to facilitate the cleaning thereof by means of a treatment with pressuri zed ozone . Said cleaning phase is preferably carried out by means of a washing machine supplied exclusively with ozone gas . Preferably, the ozone gas is under pressure , e . g . at approximately 3 . 5 atmospheres , in the drum of the washing machine . The present solution makes it possible to execute the cleaning phase without using any water or cleaning agents . The present solution ensures a high degree of fibre cleanness while making the fibres substantially unshrinkable . This advantage is particularly apparent when woollen fibres are used . In the preferred embodiment , the cleaning phase prevents the product or fabric from becoming matted, with clear benefits for garment use .

Such cleaning phase is fast ; preferably, such phase may take a time ranging from 5 minutes , e . g . for products or fabrics like cotton j ersey, to 10 minutes , e . g . for wool and cashmere products or fabrics . For thick hemp and linen-based products or fabrics , 15 to 20 minutes may be necessary . The present solution also permits giving a " sand-blasted" appearance to the items , although sand-blasting processes are no longer used because sand-blasting machines have been banned from the textile industry .

Without referring to any speci fic scienti fic theory, the Applicant has observed that gaseous ions released from ozone and implemented by the pressure within the washing machine provide considerable production advantages . In fact , the utmost cleanness of the fibres thus obtained makes it possible to , during the next dyeing phase , decrease the quantities of the components used in the dyeing baths used in prior-art dyeing methods , as will be detailed hereinafter . This cleaning phase imparts a much softer "hand" to the items . The Applicant has also observed that even Liberian fibres , which are almost impossible to wear due to their sti f fness , become incredibly performing and wearable after the cleaning phase according to the present invention .

At the end of the cleaning phase , the substances expelled from the fabrics are trapped in a suitable fi lter and eliminated . Such expelled substances are normally natural fats employed by humans in order to obtain better performing yarns prior to weaving .

The ozone treatment carried out during the cleaning phase leaves the items perfectly dry, leading to savings in terms of dryer use and lower costs and utili zation of power sources .

For the purposes of the present invention, the term Liberian fibres refers to fibres obtained from the stalk of plants like, for example, hemp, nettle, ramie, linen, gorse and liquorice.

Preferably, the dyeing method comprises a single dyeing phase .

As far as the dyeing phase is concerned, during which the product or fabric is actually dyed, several variables come into play which are always dependent on: type of fibre used in the product or fabric, weight of the product or fabric, aesthetic effect to be obtained on the product, type of dye to be used, etc.

For the purposes of the present invention, the type of dye refers to the type of natural product from which the dye to be used is obtained, e.g. fruit, root, food-grade colouring, etc.

Said at least one dyeing phase comprises a step of preparing a dyeing bath.

Said dyeing bath comprises: at least one natural dye of vegetable origin, water at room temperature; at least one natural resin, preferably of tree origin; Indian hemp pectin and sodium bicarbonate suitably dispersed in the aqueous solution .

For the purposes of the present invention, room temperature refers to a temperature of 12 to 20°C.

The water used for preparing the dyeing bath preferably has a temperature of 15 to 18°C.

In general, during the dyeing phase the dyeing bath is kept at a temperature of 10°C to 20°C.

During this phase, it is necessary to obtain high affinity between fabric and dye. In the present invention, affinity between fabric and dye is obtained by using at least one natural resin, preferably of tree origin. Said resin is suitably dispersed in a solution with a fluid, e.g. water. The dispersion of said resin in the fluid is such as to avoid the formation of lumps in the fluid.

The dyeing product or dye which is mixed with the water and the resin is always a natural product of natural, vegetable or animal origin, such as fruits, vegetables, roots, etc. As an example, a black dye is obtained from squid or cuttlefish; red is obtained from cochineal; yellow can be obtained from curcuma or saffron, preferably from curcuma since saffron is very expensive; blue can be obtained from indigo or gentian extract; green can be obtained from kiwi or, for darker tones, from chlorophyll; shaded yellow can be obtained from pear or naturally oxidized potato; orange can be obtained from beta carotene, and the colonial colour can be obtained from liquorice.

Said products may be provided in the form of powder, concentrate, puree, etc.

As previously specified, the dyeing bath comprises also Indian hemp pectin, which is particularly suitable for keeping in suspension the components of the dyeing bath, in particular the coloured particles of the dyeing products, fruits, roots, etc., and for improving the colour fastness of the dye.

As previously specified, the dyeing bath comprises also sodium bicarbonate, which is particularly suitable for maintaining the dispersion of the resins and keeping the pH as close as possible to the neutral value.

In addition to the above-mentioned elements, although in a minimal percentage, other natural products may also be used, called "compounds" in dyeing jargon, such as, for example : citrus fruit concentrate, e.g. lemon, particularly suitable for use as a fixative agent; rosemary essential oil, particularly suitable for use as an anti-fermentation and anti-oxidant agent.

In one possible alternative embodiment, orange juice concentrate may be used, instead of lemon juice concentrate, as a citrus fruit concentrate.

In one illustrative, but non-limiting, possible embodiment, the dyeing bath comprises, in addition to the dye, also the following compounds:

Lemon juice concentrate 150 parts

Hemp pectin 30 parts

Rosemary essential oil 5 parts

Damar resin 50 parts

Linseed oil 20 parts

Pinus palustris resin 50 parts

Sodium bicarbonate 5 parts.

Compared with prior-art solutions, there is a reduction by 70% of the quantities of compounds.

Said Pinus palustris resin is used as a food additive of Class E915.

The solution thus obtained is then mixed, depending on the intended use, in a percentage of 4% to 12% with water to give a dyeing bath.

As aforementioned in relation to the washing liquid, the composition of the dyeing bath may vary as a function of the fabric involved, the components thereof, and the desired final hand. A smaller quantity of product is required for clear colours than for dark colours. Liberian fibres require a smaller quantity of resin and dye , in comparison with cotton f ibres , to give the desired hue .

The dyeing bath thus composed uses water at room temperature , in particular ranging from 10 ° C to 20 ° C . Said dyeing bath is placed into a container or a washing device provided with closed fluid circuit .

The dyeing phase comprises , in addition to a step o f preparing the dyeing bath, a step of immersing the product or fabric in the dyeing bath . The immersion step simply consists of immersing the products or fabrics in the dyeing bath . In particular, said step consists of immersing the products or fabrics in the dyeing bath contained in the container .

The immersed products or fabrics are then immediately removed from the dyeing bath . Said immersion step may last 0 . 1 second to 1 minute, preferably one second .

The immersion step is followed by a hydro-extraction step . Said hydro-extraction step is preferably carried out mechanically by inserting the products , j ust removed from the dyeing bath after the immersion step, into a mechanical hydro-extractor . During this hydro-extraction step, as much dyeing bath is removed from the product or fabric as possible . In one possible embodiment , said steps of the method may be carried out by means of a washing device with a closed fluid circuit , e . g . a washing machine , in which it is possible to execute the immersion step by filling the washing drum and the hydro-extraction step by centri fugation .

More in general , the dyeing bath extracted during the hydro-extraction step can thus be reused . The addition of this step makes it possible to reuse the dyeing bath, thereby reducing the quantity of water necessary for dyeing, resulting in a water consumption amounting to 30-40% of the weight of the dyed product or fabric . The present method ensures that the first product or fabric placed in the dyeing bath and the last product or fabric placed in the dyeing bath, until the exhaustion of the liquid part of such dyeing bath, will have the same chromatic shade . This result is due to the use of said resins kept in suspension by Indian hemp pectin .

In one possible implementation of the process according to the present invention, when the dyeing bath needs to be modi fied it is possible to collect the remaining dyeing bath and store it for later use , or to supply it to an evaporator that will give , as previously speci fied, two products , namely disti lled water or H 2 O, which can then be reused during the dyeing phase , e . g . in order to prepare a dyeing bath, and dry waste , amounting to 3% of the dyeing bath at most . Such dry waste can then be stored and disposed of .

Referring back to the preferred embodiment of the process , after the hydro-extraction step the water of the dyeing bath that has remained in the products or fabrics is eliminated by executing a drying step . In particular, the dyeing phase comprises , next to the hydro-extraction step , a drying step . During said drying step, the products or fabrics are dried . In one possible embodiment , said drying step may include a centri fugation step ef fected by means of said washing device .

In the process according to the present invention, between the immersion step and the drying step no phases or steps are envisaged wherein the product or fabric just dyed undergoes a washing phase as in prior-art processes.

By way of example, the drying step can be carried out in two ways: by means of an industrial dryer, using intensive ventilation at low temperature, e.g. 50-60°C, or traditionally at room temperature, e.g. 15-25°C, e.g. by hanging the items to dry.

In general, it can be stated that the process of the present invention uses a smaller total quantity of water, in particular up to 200-400 times smaller, the weight of the product or fabric to be dyed being equal, than the industrial dyeing processes currently in use.

The dyeing process then comprises a finishing phase, preferably a single finishing phase.

In the preferred embodiment, the dyeing phase is followed by the dye finishing phase. In a first implementation, once the products or fabrics have been dried, a pausing step is executed in which the same products or fabrics remain in contact with air for a predefined period of time, preferably 24-48 hours. During the pausing step, the products or fabrics undergo no further processing or treatment. During this period of time, in which the products or fabrics undergo no treatment, the citrus fruit concentrate performs its function as a fixative of the colour on the product or fabric.

In an alternative embodiment, when the products or fabrics are dry, they undergo an oven curing step. During such step, the dyed products or fabrics are placed for more than 120 seconds into a curing oven at a temperature of approximately 160°C. Subsequently, the finishing phase comprises, regardless of the adopted implementation, a washing step in which the products or fabrics are washed in a bath of water and acetic acid, e.g. using food-grade vinegar. During the washing step, softening products of various nature may be added, which must however comply with the minimum specifications of the above-mentioned R.E.A.C.H. standard.

Also during this washing step, the temperature of the washing liquid does not exceed 40°C.

A preferred, but non-limiting, embodiment of the process according to the present invention will now be described .

The process comprises the following steps: a. placing the product or fabric into a container; b. preparing a washing liquid; c. washing the product or fabric in the container with said washing liquid; d. preparing a dyeing bath; e. keeping the dyeing bath at a temperature of 10 to 20 °C; f . immersing the product or fabric in the dyeing bath; g. executing hydro-extraction, preferably mechanically, on the product or fabric; h. drying the product or fabric; i. executing either a pausing step or an oven curing step; j . washing the product or fabric in a bath of water and acetic acid; k. repeating steps e-j for new products or fabrics that have undergone step c. until the liquid portion of the dyeing bath becomes exhausted or there are no products or fabrics left to be dyed .

The present sequence of steps does not envisage the repetition of any of such steps within such sequence or the addition of other steps that are common in industrial dyeing processes . The sequence shown above represents one possible exemplary, but non-limiting, solution .

With the proces s of the present invention, the product or fabric can be ef fectively dyed while remaining healthy for the user, i . e . non-allergenic, and is totally aseptic . For example , a garment dyed with green colour obtained from kiwi fruit will cause no allergic reaction, even i f the person wearing it is allergic to kiwi .

All colour fastness tests , which, as aforementioned, have reference values ranging from 1 to 5 , have shown values in excess of 4 , or even in excess of 5 for clear and medium colours . After the treatments carried out in accordance with the process of the present invention, the items are no longer subj ect to " loss" . For the purposes of the present invention, loss refers to the aesthetic e f fect of shrinkage of the dyed garment or discolouration with the passing of time , after repeated washing and exposure to ultraviolet rays .

The products or fabrics dyed by means of the process o f the present invention can be washed at water temperatures up to 60-70 ° C without incurring any particular problem due to dye loss .

The product or fabric dyed in accordance with the present process can be dry-cleaned, since it is resistant to hypochlorite , also known as bleach . Lastly, the product or fabric can be ironed without any particular precaution . The process according to the present invention turns out to be particularly innovative in the following aspects :

• use of raw materials that are largely, i f not totally, natural and healthy for humans ;

• increased colour fastness to washing, sun, sweat and saliva in comparison with prior-art dyeing processes ;

• high energy saving, since the process is very fast and uses cold water at 15 to 20 ° C .

• high water saving, since the same dyeing bath can be used repeatedly with unchanged results ;

• ability to reach medium-to-dark shades of colour by using vegetable dyes , which i s impossible to do with traditional systems ;

• uni form colour shades per dyeing batch .

The dyeing process according to the present invention is particularly suitable for garment , piece and/or hank dyeing .

By using a resin, the dyeing process according to the present invention coats the fibre and the fabric, ensuring greater colour fastness than industrial dyeing processes .

The present process is particularly suitable for dyeing fabrics made of Liberian fibres , cotton, nylon, polyester, wool and kevlar .

The present invention makes it possible to obtain a very high colour fastness value , in excess of 4 , also for colours like indigo , thus being clearly superior to industrial methods , which cannot reach level 3 .

Moreover, the process according to the present invention makes it possible to avoid the use of products that are deleterious for the environment , like sulphur . The process according to the present invention makes it possible to decide a priori the exact final shade of colour.

Furthermore, the product or fabric can be washed again and again, even after having been transformed into a garment, without losing colour, which will remain unchanged.

Colour fastness remains high even when the product or fabric comes in contact with substances like potassium permanganate, hydrogen peroxide and hyperchlorite, with no colour shade modifications, which is impossible to obtain by means of industrial dyeing processes.

As previously specified, the process according to the present invention allows the dyeing to be carried out at room temperature, thus eliminating the energy consumption that is typical of industrial processes, which required heating up the dyeing bath.

The process according to the present invention avoids evacuating the dyeing bath sludge. Moreover, the remaining dyeing bath can be either stored and used for other dyeing phases applying the same colour or supplied to an evaporator to obtain water to be reused for preparing a new dyeing bath.

The dyeing process according to the present invention has a low environmental impact, since it requires very little energy, e.g. electric energy, which may be self-produced, e.g. by means of a renewable energy production system, e.g. a photovoltaic system.

Barzand & Zanardo Milano S.p.A.