ITMI20102340A1 - PROCEDURE FOR THE TREATMENT OF TEXTILE MATERIALS - Google Patents

Description

â € œPROCESS FOR THE PROCESSING OF MATERIALS

TEXTILESâ €

Description

The present invention relates to a process for treating textile material, such as fabrics and yarns. In particular, the invention relates to a process for obtaining a fabric with a â € œdenim lookâ € and the fabric thus obtained.

The term â € œdenim lookâ € means an appearance similar to that of the denim fabric used in the manufacture of jeans and which behaves in a similar way towards wear.

The denim fabric is normally woven using a warp dyed with the typical colors of jeans, in particular the indigo color, and a weft of raw yarn. This weaving process gives the typical look of denim, as well as the well-known fading properties that give the garments in this fabric a worn look.

Although this fabric is among those with greater diffusion all over the world, the process for obtaining it has various drawbacks.

First of all, it involves the use of totally dedicated systems, essentially due to the pre-dyeing of the warp which limits the subsequent use of conventional production lines. Therefore, the dye batches must necessarily be very large (about 10,000 meters). An indirect consequence is a scarce flexibility of the process, so that the colors normally used are limited to indigo and sulfur. In fact, each color variant requires the repetition of all the steps of the process, since the dye is placed at the beginning of the process.

In view of the foregoing, it is clear that the denim fabric production plants are located in large dedicated factories, with considerable energy consumption and a heavy ecological impact. In fact, large quantities of polluting chemical compounds are used (caustic soda, hydrosulfite, sodium chloride) which remain in the wastewater, together with the hydrolyzed dye of the dyeing baths. Large volumes of polluted water with a high color discharge are also created during the washing after dyeing phase.

The energy consumption of these plants is very high, due to the large volumes involved and the high temperatures (90 ° C for pre-treatment and 70 ° C for dyeing).

Furthermore, during weaving the indigo powder released from the warp represents a major risk factor for the health of the operators, due to the generation of micro-powders.

Further drawbacks are due on the one hand to the weakening of the denim that occurs following treatments on the garment (washing, â € œstone washâ €, chlorination, etc.), on the other hand to the poor solidity of the dye by rubbing at damp, which entails the risk of dirtying the surfaces that come into contact with a denim garment worn damp.

Furthermore, the procedure described above can be used only for cotton yarns, thus excluding all other fibers that could bring interesting functional and aesthetic characteristics.

An object of the present invention is therefore that of providing a more flexible, economically advantageous and ecologically sustainable process, which allows the obtaining of fabrics with a â € œdenim lookâ € in a wide range of colors.

A further object is to provide a fabric with a â € œdenim lookâ € that provides the typical fading effect due to wear of the garment, but not from wet rubbing and that at the same time presents a high resistance to the structural weakening of the fabric itself.

The process of the invention provides for a cationization treatment of the surface of the yarn which constitutes the warp, as will be better described below.

The idea of chemically modifying the surface of a thread or fabric by means of cationic charges capable of binding with anionic charges typical of acid and / or reactive dyes is known and has mainly been applied to the following processes:

i) Application of cationic resins on staple fibers with autoclave exhaustion processes: this procedure allows the impregnation of the entire fiber and therefore the subsequent dyeing of the entire mass of the yarn;

ii) Cationization of non-woven fabric for â € œcolour-catcherâ € effects with exhaustion and / or foulard applications: this procedure is dedicated to the production of sheets with â € œdye-scavengerâ € properties that can be used in washing colored and colorless garments in the washing machine;

iii) Application of cationic resins made directly on the garment: in this case the cationization of the entire fabric is obtained, with consequent homogeneous dyeing of the garment.

In the international application published under no. WO 20087115685, the personalized dyeing of a garment obtained from a fabric totally or partially made up of a cationic cotton yarn is described. However, the process for manufacturing said cationic cotton is not described, which suggests the use of the traditional cationization of the staple fiber.

The problem underlying the present invention is therefore that of overcoming all or part of the drawbacks discussed above in the conventional manufacturing process of the denim fabric.

This problem is solved by a process and a yarn and a fabric obtainable according to this process, as outlined in the attached claims, the definitions of which form an integral part of the present description.

Further characteristics and advantages of the invention will become clearer from the description of some examples of embodiment, given below by way of non-limiting example, with reference to the following figures:

Figure 1 represents a schematic view of a plant for the implementation of the process of the invention;

Figure 2 represents a schematic cross-sectional view of the warp yarn obtainable with the process of the invention.

As shown in figure 1, the system, indicated as a whole with the number 1, is completely conventional and includes:

- a first treatment section (cationization) 2, consisting for example of a foulard in which the warp is passed at a predefined temperature and time,

- a subsequent drying and polymerization section 3, in which the warp exiting the first treatment section is passed between cylinders 6, preferably Teflon-coated cylinders, at a first predefined temperature and pressure,

- a second treatment section 4 (sizing), consisting for example of a padder in which the cationized and polymerized warp is passed at a predefined temperature and time,

- a subsequent drying section 5, in which the warp leaving the second treatment section is made to pass between cylinders 7, preferably Teflon-coated cylinders, at a second predefined temperature and pressure.

A similar system (not shown) can include drying sections 3, 5 in parallel instead of in series. In this case, both treatment sections 2, 4 will be used alternatively for cationization or for sizing, thus operating a double passage of the warp in the plant or the arrangement of a second twin plant downstream of the first . This solution is preferable when the warp is made up of more than 10,000-15,000 threads.

The process of the invention includes the following operational phases in succession:

a) preparation of a warp composed of a raw yarn;

b) coating said raw warp yarn with a composition containing a cationizing agent;

c) drying and polymerization of said cationizing agent on said raw warp yarn;

d) sizing of said raw warp yarn obtained according to step c);

e) drying of said raw warp yarn obtained according to step d).

Step a) of preparing a raw yarn warp comprises placing said raw yarn on conventional beams 8 from 4,000 to 15,000 threads.

Said raw yarn is chosen from a cotton, wool, linen, synthetic or mixed fiber yarn. The raw yarn can be obtained according to conventional techniques, which will therefore not be described in detail here.

The step b) of coating the raw yarn with a cationizing agent comprises the passage of the raw yarn of the warp in said first treatment section 2. As shown in figure 1, this passage is conveniently carried out in a traditional foulard containing a composition aqueous of a cationizing agent.

The aqueous composition of cationizing agent according to the invention comprises:

1) a cationizing agent,

2) a heat curable resin,

3) ammonium sulfate,

4) a non-ionic wetting agent.

In a preferred embodiment of the process, the aqueous composition of the invention has the following composition: 1) cationizing agent 80-120 g / L; 2) heat polymerizable resin 50-70 g / L; 3) ammonium sulfate 7-9 g / L; 4) non-ionic wetting agent 2-4 g / L.

In one embodiment, the cationizing agent is a quaternary ammonium salt of aliphatic amines, for example Reapret MDZ of the Giovanni Bozzetto S.p.A.

In one embodiment, the heat-curable resin is a melamine / formaldehyde-based resin, for example Reacel MFC from Giovanni Bozzetto S.p.A.

In one embodiment, the non-ionic wetting agent is a mixture of polyglycol ethers of fatty acids, for example Finbil 3001 from Giovanni Bozzetto S.p.A.

The function of ammonium sulphate is to catalyze the polymerization of the resin and to regulate the pH of the solution.

The heat-curable resin covers and films the surface of each single warp homogeneously and prevents the cationizing agent from penetrating deeply. The non-ionic wetting agent regulates the wettability of the raw yarn and, when used in the quantities indicated above, allows the surface coating of the yarn, avoiding obtaining a total impregnation of the same. This effect is also obtained thanks to the viscosity of the solution thus obtained and to the process parameters as defined below.

The fact that the cationizing agent is present only on the surface of the raw yarn is essential for the purposes of the present invention, as it determines, in the subsequent dyeing step, a superficial coloring only.

According to an embodiment, step b) of coating the raw warp yarn with said composition of cationizing agent is carried out at temperatures between 30 ° C and 40 ° C and at a pH of about 5, at a speed of 20-50 m / min and with a degree of squeezing such as to obtain a pick-up of 60-80%.

The concentration of the reagents, the viscosity of the solution, the squeezing pressure that eliminates the excess of cationizing composition on the yarn allow not to exceed the physical saturation limit on the treated surface. A possible excess of resin, in fact, could complex the dye in the bath of the subsequent dyeing step, thus obtaining an effect opposite to the desired one of fixing the anionic dye.

The subsequent phase c) of drying and polymerization involves a treatment temperature of about 140 ° C and a contact time of about 30-50 seconds with a speed in the range of 20-36 m / min, which leads to the formation of a thin and uniform film of polymerized resin on the surface of the yarn, which incorporates the cationizing agent. The temperature can however be adjusted according to the polymerization temperature of the resin used and therefore vary with respect to the temperature reported here. In general, temperatures above 100 ° C will be required to achieve polymerization of the resin.

The yarn thus obtained preferably has a residual humidity of 3-4%.

The surface layer of resin also gives the yarn strength and elasticity.

The sizing phase d) allows to obtain high yields on the loom (80-90%) and to avoid pilling effects. Sizing is obtained by passing the warp yarn, previously treated according to steps b) and c), in the second treatment section 4, in particular in a foulard in which there is a composition of sizing.

The size composition is selected so as to be compatible with the cationizing agent previously deposited on the yarn and is preferably free of antistatic agents.

According to an embodiment of the invention, a size composition comprises a mixture of polyvinyl alcohols (PVA) and polysaccharides. For example, the commercial product Larotex OL S from the Laros company could be used. The weight percentage of the size in the composition is between 8 and 10% of the required bath volume.

The composition of the size does not vary depending on the characteristics of the warp, such as a variable count between Ne 9/1 and Ne 40/1 and a number of threads between 4,000 and 10,000, as is the case for traditional sizes.

This size composition allows to associate the typical advantages of PVA such as the formation of an elastic film, a good hand, a scarce influence of humidity, with the advantages of polysaccharides, such as good sizing properties, good melting behavior and insensitivity to alkaline conditions.

The size is first fired at 90 ° C according to a conventional process, then it is cooled to less than 70 ° C and preferably between 55 and 65 ° C or to about 60 ° C and maintained at this temperature during the passage of the yarn to be treated. In fact, higher temperatures could lead to the removal of at least part of the cationized resin.

The yarn is passed through the sizing section at a speed of 20-50 m / min and is squeezed with a refractometric degree of application of about 12 and a residual charge on the yarn of 6-8% by weight.

The warp yarn thus treated is then dried (step d)) in the drying section 5 and then rewound in a conventional beam 9.

In one embodiment, the process of the invention further comprises at least one of the following steps in succession:

f) loom weaving of the warp yarn obtained from step e) with a weft of raw yarn;

g) dyeing of the fabric obtained from step f) with anionic dyes;

h) post-treatment of the colored fabric obtained from step g).

Phase f) of weaving can be carried out using conventional wefts, depending on the aesthetic effect that you want to give to the fabric.

The dyeing step g) is preferably carried out without removing the size and without pre-dyeing purging.

In one embodiment, the dyeing step g) provides for an exhaustion or padbatch dyeing with acid dyes, preferably premetallized, or reactive in an acid bath.

The dyes must be pre-selected according to both the light fastness of the substrate dye and the size of the color molecules.

The dyeing takes place through the salification by the negative ions of the dye of the cationic groups of the cationizing agent that covers the warp yarn.

The dyeing step g) is carried out in the absence of electrolyte (for example, sodium chloride) and fixing with alkali. In this way, only the coloring of the warp is obtained, while the weft does not fix the dye and remains raw. The color remains fixed only on the warp, thanks to the presence of the cationizing agent.

Phase h) of post-treatment may include point-blank and / or mild bleaching with hydrogen peroxide. These operations should not be carried out before dyeing step g). All conventional cotton finishing processes are also possible, as the fabric obtained according to the process of the invention is stable under high temperature (boiling) and highly alkaline (mercerisation) treatments.

The treatments on the garment obtained with a fabric according to the invention, such as â € œchemical polishingâ € with enzymes, â € œstone washingâ € or treatments with chlorine or permanganates, lead to the desired fading effects by progressive color removal on the surface of the fiber which degrades to the natural raw color of the internal mass of the fiber, demonstrating that the process of the invention actually leads to a superficial dyeing of the warp yarn.

A further object of the present invention is a yarn 100, the structure of which is shown in figure 2, which comprises:

i) a core 101 of raw yarn;

ii) a layer 102 comprising a resin incorporating a cationizing agent;

iii) an outer layer 103 comprising a size;

iv) optionally, a dye fixed to the outer surface of the yarn 100 by means of said cationizing agent.

In one embodiment, the raw yarn core 101 is made from cotton, wool, linen, synthetics or blended yarns.

In one embodiment, the cationizing agent is a quaternary ammonium salt of aliphatic amines, for example Reapret MDZ of the Giovanni Bozzetto S.p.A.

In one embodiment, the heat-curable resin is a melamine / formaldehyde-based resin, for example Reacel MFC of the firm Giovanni Compa S.p.A.

According to an embodiment of the invention, the size comprises a mixture of polyvinyl alcohols (PVA) and polysaccharides.

In one embodiment, the dye is an acid anionic dye.

A further object of the invention is a fabric with an orthogonal structure, comprising a warp and a weft, in which said warp is constituted by a yarn 100 which comprises:

i) a core 101 of raw yarn;

ii) a layer 102 comprising a resin incorporating a cationizing agent;

iii) an outer layer 103 comprising a size,

and said weft is constituted by a raw yarn, and in which said warp comprises a surface dyeing with an anionic dye.

A further object of the invention are manufactured articles obtained with the fabric of the invention or comprising a yarn as defined above. For example, these artifacts could be clothing, accessories (bags, wallets, belts, etc.), furnishings or other items.

The advantages of the present invention are manifold.

First of all, the fact that the dye is applied on the raw fabric instead of on the warp - as in the traditional procedure for a denim fabric - involves the use of conventional systems. Typical dyeing batches of a batch or exhaustion pad dyed piece (from 50 to 4000 m) can be used, without the need to work with large batches (10,000 m) as in the conventional denim process.

A further consequence is that a wide range of color variations and tones can be obtained, resulting from the use of reactive dyes and / or bright acids, which makes the inventive process very flexible. This also makes sampling with reduced quantities of fabric simpler and more feasible.

The ecological and energy advantages are not to be neglected either. The process of the invention avoids the use, during the dyeing phase, of caustic soda and sodium chloride, which normally require waste water treatment. Furthermore, for dyeing to exhaustion the process exhausts the dye in the dyeing bath and therefore the polluting load is minimal. Also for pad-batch dyeing the color quantities are less than 15-25 g / L. The first washing waters are also almost devoid of color, as it is strongly bound to the cationic groups of the yarn. The volumes of treatment water are in any case very small compared to the conventional denim process.

Process times are reduced by about 50-60% at room temperature compared to the conventional process and by about 40% at temperatures below 70 ° C.

The weaving takes place without the presence of dyes and the dust is generated only by the sizing products used in traditional weaving with low environmental impact.

With the process of the invention, the treatments on the garment provide the same fading effects as the traditional denim fabric, but the resistance of the garment over time is superior thanks to the presence of the dyed cationized resin which is gradually removed in the treatments mechanical while preserving the underlying yarn.

The binding of the dye to the cationic groups of the warp is strong, which results in a high rubbing fastness and reduces the transfer of wet color. Resistance to alkali is also very high.

The use of yarns in various raw materials, both natural and synthetic, increases the flexibility of the process.

It is evident that only some particular embodiments of the present invention have been described, to which the expert in the art will be able to make all the modifications necessary for its adaptation to particular applications, without departing from the scope of protection of the present invention.

Claims (30)

CLAIMS 1. Process for treating textile materials, comprising the following operational steps in succession: a) preparation of a warp composed of a raw yarn; b) coating said raw warp yarn with a composition containing a cationizing agent; c) drying and polymerization of said cationizing agent on said raw warp yarn; d) sizing of said raw warp yarn obtained according to step c) by passing through a sizing composition; e) drying of said raw warp yarn obtained according to step d). 2. Process according to claim 1, wherein said step a) of preparing a raw yarn warp comprises arranging said raw yarn on beams from 4,000 to 15,000 yarns. 3. Process according to claim 1 or 2, wherein said raw yarn is selected from a cotton, wool, linen, synthetic or mixed fiber yarn. Process according to any one of claims 1 to 3, wherein said process is carried out in a plant (1) comprising: - a first treatment section (2), preferably consisting of a foulard in which the warp is passed at a predefined temperature and time, - a subsequent drying and polymerization section (3), in which the warp exiting the first treatment section is passed between cylinders (6), preferably Teflon-coated cylinders, at first predefined temperature and pressure, - a second treatment section (4), preferably consisting of a padder in which the cationized and polymerized warp is passed at a predefined temperature and time, - a subsequent drying section (5), in which the warp leaving the second treatment section is passed between cylinders (7), preferably Teflon-coated cylinders, at second predefined temperatures and pressures. 5. Process according to claim 4, wherein said step b) of coating the raw yarn with a cationizing agent comprises passing the raw yarn of the warp into said first treatment section (2) containing an aqueous composition of a cationizing agent . 6. Process according to any one of claims 1 to 5, wherein said aqueous composition of cationizing agent comprises: 1) a cationizing agent, 2) a heat curable resin, 3) ammonium sulfate, 4) a non-ionic wetting agent. 7. Process according to claim 6, wherein said aqueous composition has the following composition: 1) cationizing agent 80-120 g / L; 2) heat polymerizable resin 50-70 g / L; 3) ammonium sulphate 7-9 g / L; 4) non-ionic wetting agent 2-4 g / L. 8. Process according to claim 6 or 7, wherein said cationizing agent is a quaternary ammonium salt of aliphatic amines. Process according to any one of claims 6 to 8, wherein said heat-curable resin is a melamine / formaldehyde-based resin. 10. Process according to any one of claims 6 to 9, wherein said nonionic wetting agent is a mixture of polyglycol ethers of fatty acids. 11. Process according to any one of claims 1 to 10, wherein said step b) of coating the raw warp yarn with said composition of cationizing agent is carried out at temperatures between 30 ° C and 40 ° C and at pH of about 5, at a speed of 20-50 m / min and with a degree of squeezing such as to obtain a pick-up of 60-80%. 12. Process according to any one of claims 1 to 11, wherein said drying and polymerization step c) provides a treatment temperature of about 140 ° C and a contact time of about 30-50 seconds with speed in the range of 20-36 m / min. 13. Process according to claim 12, wherein the yarn obtained according to step c) has a residual humidity of 3-4%. 14. Process according to any one of claims 4 to 13, wherein said sizing step d) comprises the passage of said warp yarn, previously treated according to steps b) and c), in said second treatment section (4 ) in which there is a size composition. Process according to any one of claims 1 to 14, wherein said size composition comprises a mixture of polyvinyl alcohols (PVA) and polysaccharides and is preferably free of antistatic agents. 16. Process according to claim 15, wherein the weight percentage of the size in the composition is comprised between 8% and 10% of the required bath volume. 17. Process according to any one of claims 1 to 16, wherein said size is first fired at 90 ° C, then cooled to less than 70 ° C or between 55 and 65 ° C or to about 60 ° C and maintained at this temperature during the passage of the yarn to be treated. 18. Process according to any one of claims 1 to 17, wherein said yarn is passed through the size composition at a speed of 20-50 m / min and squeezed with a refractometric degree of application of about 12 and residual charge on the yarn of 6-8% by weight. 19. Process according to any one of claims 1 to 18, further comprising at least one of the following steps in succession: f) loom weaving of the warp yarn obtained from step e) with a weft of raw yarn; g) dyeing of the fabric obtained from step f) with anionic dyes; h) post-treatment of the colored fabric obtained from step g). 20. Process according to claim 19, wherein said dyeing step g) is carried out without removing the size and without pre-dyeing purging. 21. Process according to claim 19 or 20, wherein said dyeing step g) provides for an exhaustion or pad-batch dyeing with acid dyes, preferably pre-metallized, or reactive in an acid bath, in the absence of electrolytes and fixing with alkali. 22. Process according to any one of claims 19 to 21, wherein said post-treatment step h) comprises one or more of the following operations: point-blank, mild bleaching with hydrogen peroxide, mercerization, â € œchemical polishingâ € with enzymes, â € œstone washingâ €, treatments with chlorine or permanganates. 23. Yarn (100), which includes: i) a core (101) of raw yarn; ii) a layer (102) comprising a resin incorporating a cationizing agent; iii) an outer layer (103) comprising a size; iv) optionally, a dye fixed to the outer surface of said yarn (100) by means of said cationizing agent. Yarn (100) according to claim 23, wherein said core (101) of raw yarn is made of cotton, wool, linen, synthetics or blended yarns. Yarn (100) according to claim 23 or 24, wherein said cationizing agent is a quaternary ammonium salt of aliphatic amines. Yarn (100) according to any one of claims 23 to 25, wherein said heat curable resin is a melamine / formaldehyde based resin. Yarn (100) according to any one of claims 23 to 26, wherein said size comprises a mixture of polyvinyl alcohols (PVA) and polysaccharides. Yarn (100) according to any one of claims 23 to 27, wherein said dye is an acid anionic dye. 29. Orthogonal structure fabric, comprising a warp and a weft, wherein said warp is constituted by a yarn (100) as defined in any one of claims 23 to 28, which comprises: i) a core (101) of raw yarn; ii) a layer (102) comprising a resin incorporating a cationizing agent; iii) an outer layer (103) comprising a size, in which said weft consists of a raw yarn, and in which said warp comprises a surface dyeing with an anionic dye. 30. Articles obtained with a fabric as defined in claim 29 or comprising a yarn as defined in any one of claims 23 to 28.