ITUB20155790A1 - COMPOSITION FOR THE TREATMENT OF A CELLULOSIC SUBSTRATE AND METHOD OF COLORING THE CELLULOSIC SUBSTRATE - Google Patents

Description

Description of an invention patent entitled: COMPOSITION FOR THE TREATMENT OF A CELLULOSE SUBSTRATE AND METHOD OF COLORING THE CELLULOSE SUBSTRATE

DESCRIPTION

The present invention relates to a composition for the treatment of a cellulosic substrate in view of its coloring by printing, as well as to a kit for this treatment, to a method for coloring the cellulosic substrate, and to a use linked to this method.

More particularly it refers to a composition and a kit for the treatment of cellulosic fibers for their coloring by printing, and to a method and a use for the coloring of cellulosic fibers by means of monochlorotriazine dyes.

It has long been known to dye fabrics using any digital printing method for applying the dye to the fabric, such as by inkjet printing or rotary printing.

Using a printing method to color the fabrics, the quality of the colored fabric also depends on the fixing method used after the staining step.

Excellent results are obtained with fixing by means of vaporization, however it is known that vaporization involves various disadvantages, such as, for example, a large consumption of water, time and logistics; an increase in the risk of defects related to the repeatability of the tones and the migration of dyes that occurs during the vaporization phase; the repeatability of the fixed dye percentage is also variable because depending on the settings, vaporization determines different kinetics in the dye fixing reaction, subsequently causing a migration of the unreacted dye during the subsequent washing, with consequent pollution of the printed areas and white unprinted areas.

A known alternative fixing method is heat setting, which consists in fixing the dyes by applying dry heat. This process is more advantageous in terms of water consumption, application times, washing efficiency, and reduction of the size of the system. Furthermore, it has been found that after a heat setting the quantity of dye lost during the washing phase is less than with vaporization.

However, it has been noted that heat setting has a negative influence on the final appearance of the colored fabric. In particular, the colors obtained are visibly less intense, and the fabric takes on a slightly rough hand to the touch.

The aim of the present invention is therefore to provide a composition and a kit for the treatment of a cellulosic substrate which allow the latter to be colored by printing and which allows an optimal final product to be obtained even after heat setting.

Another object of the invention is to propose a method for coloring a cellulosic substrate in which the coloring of the cellulosic substrate can be carried out by means of inkjet printing or rotary printing.

These and other objects are achieved by realizing a composition, a kit, a use and a method made according to the technical teachings of the attached claims.

The present invention relates to a composition for the treatment of a cellulosic substrate for its coloring by printing. In the present context, printing is to be understood as any type of printing suitable for the application of a dye on a cellulosic substrate, by means of digital printing methods such as for example inkjet printing, rotary printing, square printing or others.

In the context of the present invention, cellulosic substrate refers to cellulosic fibers in the format of fabrics and yarns in general.

According to the invention, the composition comprises nicotinamide, a polydimethylsiloxane and urea.

Nicotinamide acts as an activator, or catalyst, of the reaction of the dye with the cellulosic substrate. This activator function is most efficient with monochlorotriazine dyes.

Polydimethylsiloxane, on the other hand, has a corrector function as it closes the porosity of the cellulosic substrate a lot, making it flatter. This has several advantages, such as a better optical density of the inks. Furthermore, it has been found that the use of polydimethylsiloxane, with nicotinamide, allows to obtain a better color rendering on the fabric, with more intense tones and brighter colors even when a printing process combined with heat setting is used. Furthermore, the fabric obtained is softer to the touch than a fabric treated only with nicotinamide. This reactive polydimethylsiloxane is permanent and therefore cannot be washed away in subsequent washes and does not in any way affect the final fastness of the applied dyes.

Urea acts as a moisturizer for the heat setting phase. More precisely, during the application of heat linked to the thermo-fixing, the urea creates a network on the cellulosic substrate that contains the dye in non-aggregated form and maintains it in this state up to high temperatures, in addition to the function of retaining water. necessary for the reaction of the dye with the cellulosic substrate at the aforementioned high temperatures.

Preferably, the polydimethylsiloxane is of the hydrophilic type, reactive with the substrate, permanent and with a low refractive index. By permanent it is meant that the polydimethylsiloxane remains on the cellulosic substrate even after washing. With low refractive index we mean a refractive index lower than 1.4, in order to have a greater intensity and brilliance of the tint. For this purpose, it is also advisable to add an oil to the polydimethylsiloxane, in order to have a second refractive index different from that of the polydimethylsiloxane, and thus further improve the brilliance and intensity of the tint.

Even more preferably, the polydimethylsiloxane is of the amino type, ie it comprises at least one amino function.

It is particularly advantageous to provide that the polydimethylsiloxane is in a macroemulsion, so as to make the cellulosic substrate less porous, in order to achieve a better optical density of the inks.

Preferably, nicotinamide is present at a concentration between 5 and 25 g / kg, polydimethylsiloxane between 30 and 90 g / kg, and urea between 50 and 400 g / kg with respect to the total weight of the composition. Even more preferably, the composition comprises between 10 and 20 g / kg of nicotinamide, between 40 and 80 g / kg of polydimethylsiloxane, and between 200 and 300 g / kg of urea with respect to the total weight of the composition.

Preferably, the composition also comprises a thickener, which can be of natural or synthetic origin. According to a preferred embodiment of the invention, the thickener is selected from alginates, polyacrylates or carboxymethylcellulose. These compounds have the advantage of not containing OH groups susceptible to react with the dye, and therefore such as to compete with the OH groups of the cellulosic substrate, which would lead to a decrease in the dye available for reaction with the cellulosic substrate.

Alginates can be of the high, medium or low viscosity type, and carboxymethylcellulose can have varying degrees of substitution.

Preferably, the thickener comprises medium / high viscosity alginates which have the advantage of giving rise to a more regular porous structure on the cellulosic substrate than acrylates and carboxymethylcellulose for their thermal stability, i.e. they maintain an adequate porous structure. especially in the temperature range necessary for heat setting.

As is known, the regularity of the porous structure benefits the regularity of the optical density of the ink deposited on the substrate. A correct pore size at the high temperatures in use determines a correct crossing of the ink without creating interference of spherical dimensions for the size of the coloring molecules, but not porous dimensions so high as to sufficiently prevent the migration of the ink. It is also evident that an increase in the surface area of the porous structure leads to an increase in its porosity and, a greater porosity leads to a lower coalescence of the ink drops on the substrate, and therefore a more regular optical density. Furthermore, it has been observed that alginate-based thickeners allow excellent control of the migration of the dye even at high temperatures, since their reticular structure, and therefore their viscosity, persists even with the rise in temperature, and therefore does not by decomposing its porous structure and only decreasing its viscosity, it thus favors the migration of the dye from the thickener to the cellulose while maintaining both the desired print definition, thanks to the residual viscosity, and the necessary contact with the cellulosic substrate, thanks to the contained migration, for the dye-fiber reaction to take place.

Among alginates, medium / high viscosity alginates give the best results in terms of optical density of the print and color rendering. It should also be noted that medium / high viscosity alginates maintain a regular porous network especially even in alkaline conditions, in particular at pH 8 - 9.

Preferably, the composition according to the invention also comprises at least one rheological stabilizer selected from the terpenes. Even more preferably, the terpene is pinene. Advantageously, it is possible to provide the pinene in the form of pine oil, and integrate it into the composition by means of an aqueous emulsion of the nicotinamide in the pine oil; this terpene has the ability to modify the rheology of the printing paste making it less pseudoplastic, therefore more Newtonian, and increasing the transfer capacity of the printing paste to the substrate during the preparation phase for inkjet printing or in direct printing through cylinder and frame silkscreen.

According to a preferred aspect of the invention, the composition also comprises a hydrophilic polydimethylsiloxane with a low refractive index. As already mentioned, a low refractive index means a refractive index lower than 1.4.

The presence of the low refractive index polydimethylsiloxane allows to decrease the refractive index of the substrate thus increasing the optical path of the incident light inside the fiber on which the ink is deposited. This involves a decrease in the white reflected from the substrate, and therefore a relative increase in the optical density of the printed color.

Preferably, the composition comprises nicotinamide, hydrophilic and reactive low refractive index polydimethylsiloxane, an increased amount of urea, a thickener selected from alginates, carboxymethylcellulose and polyacrylates, sodium bicarbonate and a meta-nitrobenzene-based antireducant. -sulfonate.

The composition may also be part of a cellulosic substrate preparation kit. This kit is intended as part of the present invention.

The above composition can be applied directly to the cellulosic substrate before the printing step and this step of the process is called "preparation", if inkjet printing is envisaged.

If, on the other hand, one proceeds with a rotary printing, the composition must be provided in the form of a mixture which also includes at least one dye. This mixture for coloring a cellulosic substrate is also to be understood as protected by the present application.

In the mixture, the dye is preferably a monochlorotriazine dye, and even more preferably a monochlorotriazine dye monoreactive. It has been verified that when subjected to heat setting, mono-reactive monochlorotriazine dyes are more fixed than bi-reactive monochlorotriazine dyes.

The present invention also relates to a method for coloring a cellulosic substrate, comprising, not necessarily in the order indicated, the steps of:

a) applying a composition according to the invention to the cellulosic substrate

b) drying the cellulosic substrate;

c) applying at least one dye by printing;

d) fix the dye by heat setting; And

e) washing the cellulosic substrate.

The fact of using a composition comprising nicotinamide, polydimethylsiloxane and urea allows to avoid that the fixing step d) is carried out by vaporization, and to maintain a high quality of the colored cellulosic substrate, both in the color rendering, in the maintenance white (non-printed parts), and the softness of the fabric.

Preferably, the dye is a monochlorotriazine dye. Even more preferably, the dye is a monoreactive monochlorotriazine dye. It has been found that monoreactive monochlorotriazine dyes, when subjected to heat setting, are fixed faster than in the vaporization process resulting in an improvement in production times than in energy expenditure, while as regards the quantity of reacted dye it is comparable. Bi-reactive monochlorotriazine dyes, on the other hand, are less effectively fixed by heat setting.

According to a first variant of the method, step c) of applying the dye is performed by inkjet printing of the dye on the cellulosic substrate.

In this case, steps a), b) and c) are carried out in succession, and in the order indicated, i.e. after having treated the substrate with the composition according to the invention, the treated substrate is dried and, subsequently, color it by inkjet printing.

According to a second variant of the method, step c) of applying the dye is performed by rotary printing.

In this case, however, it is necessary to use the aforementioned mixture, which comprises both the composition according to the invention and the dye. It can be seen that steps a) of applying the composition and c) of applying the dye are simultaneous, and that they take place before step b) of drying the cellulosic substrate.

According to a preferred aspect of the invention, step a) of treating the cellulosic substrate takes place by means of a substrate impregnation procedure, in particular by means of a batch pad or rotary printing process.

The washing step e) is preferably carried out by means of at least one fatty amine, preferably ethoxylated. This surfactant acts as a dye inhibitor during the washing step of the colored cellulosic substrate.

According to a preferred aspect of the invention, the washing is also carried out by means of sodiumdodecylbenzenesulphonate, mixed with the fatty amine. In fact, it has been found that this compound, when placed in the presence of the ethoxylated fatty amine, produces a synergistic effect of washing efficiency and inhibition of the redeposition of the dye, thus resulting in an increased washing efficiency of the unfixed colors and an excellent maintenance of white and original print tones due to the pollution of the unfixed dye. It has been found that this washing kit decreases to only three continuous washing tanks compared to the six usually used, thus improving water consumption.

Advantageously, the ethoxylated fatty amine, or the mixture of the fatty amine with sodium dodecylbenzenesulphonate, is sold in the form of a kit for washing a cellulosic substrate after printing and heat setting.

Claims (1)

CLAIMS 1.Composition for the treatment of a cellulosic substrate for its coloring with monochlorothyriazine dyes, comprising nicotinamide as an activator, polydimethylsiloxane, e urea. 2. A composition according to claim 1, wherein the polydimethylsiloxane is of the permanent reactive hydrophilic type and has a low refractive index, 3. A composition according to claim 1 or 2, wherein the polydimethylsiloxane is of the amino type. 4. A composition according to any one of the preceding claims, wherein the polydimethylsiloxane is provided in a macroemulsion. 5. A composition according to one or more of the preceding claims, comprising between 5 and 25 g / kg of nicotinamide, between 30 and 90 g / kg of polydimethylsiloxane, and between 50 and 400 g / kg of urea with respect to the total weight of the composition. 6. A composition according to one or more of the preceding claims, comprising between 10 and 20 g / kg of nicotinamide, between 40 and 80 g / kg of polydimethylsiloxane, and between 200 and 300 g / kg of urea with respect to the total weight of the composition. 7. A composition according to one or more of the preceding claims, comprising at least one thickener selected from an alginate, a polyacrylate or a carboxymethylcellulose. 8. A composition according to the preceding claim, comprising a rheological stabilizer based on pinene. 9. Mix for coloring a cellulosic substrate by printing, comprising the composition according to one or more of the preceding claims, and at least one dye. 10. Kit for the treatment of a cellulosic substrate for its coloring by means of monochlorotriazine dyes, comprising the composition according to one or more of claims 1 to 9. 11. Use of a polydimethylsiloxane together with nicotinamide for the treatment of a cellulosic substrate for its coloring by printing. 12. Method for staining a cellulosic substrate, comprising, not necessarily in the following order, the steps of: a) applying to said cellulosic substrate a composition according to one of claims 1 to 8; b) drying said cellulosic substrate; c) applying at least one dye to said cellulosic substrate by printing; d) fixing said dye by heat setting; And e) washing said cellulosic substrate. Method according to the preceding claim, wherein the step c) of applying the dye is performed by inkjet printing, the steps a) and c) being performed one after the other. Method according to claim 12, wherein step c) of applying the dye is performed by rotary printing, steps a) and c) being performed simultaneously, and before step b) of drying the cellulosic substrate. Method according to one of claims 12 to 14, wherein the dye is a monochlorotriazine dye. Method according to the preceding claim, wherein the dye is a monoreactive monochlorothriazine dye. Method according to one or more of claims 12 to 16, wherein the dye is applied by ink-jet printing. 18. Method according to one or more of claims 12 to 17, wherein step a) of treating the cellulosic substrate is carried out by means of an impregnation or rotary printing process. 19. Method according to one or more of claims 12 to 17, wherein step e) of washing is carried out with an ethoxylated fatty amine. Method according to the preceding claim, in which the washing step e) is carried out with the sodiumdodecylbenzenesulphonate mixed with the ethoxylated fatty amine.