WO2017162625A1

WO2017162625A1 - Textile printing paste

Info

Publication number: WO2017162625A1
Application number: PCT/EP2017/056623
Authority: WO
Inventors: Dario Chiavacci; Maurizio GALLUCCI; Mattia CANZIANI; Giuseppe PIRRONE; Michele MONICA; Giovanni Floridi; Giuseppe Li Bassi
Original assignee: Lamberti Spa
Priority date: 2016-03-23
Filing date: 2017-03-21
Publication date: 2017-09-28
Also published as: ITUA20161934A1

Abstract

The present invention relates to a method of preparing a textile printing paste comprising the step of providing a shaped solid additive for textile printing.

Description

TEXTILE PRINTING PASTE

FIELD OF THE I NVENTION

The present invention relates to a method of preparing a textile printing paste comprising a shaped solid additive for reactive dye printing and a reactive dye.

BACKGROUND OF TH E ART

The pastes for reactive dye printing serve to transfer reactive dyes onto a textile material in a controlled way. Their composition is critical and largely determines the quality of the final article.

The pastes for reactive dye printing are usually prepared by solubilizing one or more thickeners (thickening agents) in water and, successively, by adding other possible chemical auxiliaries useful to the process and the reactive dye(s). Examples of such chemical auxiliaries are bases, hydrotropes, reduction inhibitors, wetting agents, emulsifiers, dispersing agents, preservatives, sequestrants (water softeners), and defoamers.

The main function of thickeners is to provide the paste with suitable rheological properties in order to allow a better control in the design pattern reproduction onto the textile material .

Commonly used thickeners are natural, semisynthetic or synthetic water soluble polymers of high molecular weight.

In cases where high ionic environments are encountered, such as in printing pastes containing reactive dyes, polymers with particular characteristic are required .

Among the natural polymers, alginate is usually considered as reference in textile printing of reactive dyes, because it shows a suitable ecotoxicological profile and good solubility, it performs well as rheology modifier and it is easily removed by washing at the end of the printing process. In addition, it guarantees a good color yield and a proper definition of printing . Alternative thickeners are carboxymethyl cellulose, preferably having a high degree of substitution (DS), typically above 1.5, and (meth)acrylic acid and (meth)acrylamide homo- and co-polymers. The bases, such as sodium carbonate and sodium bicarbonate, increase l the reactivity of the reactive dye toward the hydroxyl group of the cellulose.

The hydrotropes are those agents capable of converting the dispersion of dyes or optical brighteners that are insoluble or low soluble in water into a stable deflocculated form, without any chemical reaction occurring between the dyes or the optical brighteners and the hydrotropic substance.

The reduction inhibitors are weak oxidizing agent, which avoid the degradation of the reactive dyes.

Many of these auxiliaries are added into the printing paste as powders, which, however, are source of various problems.

In fact, powders by their nature have very large surface areas susceptible to humidity and/or bacterial growth .

Moreover, the handling of such powders and dust generation during processing create environmental and health problems that must be dealt with by the manufacturer and the final user.

Furthermore, thickeners in form of powders are difficult to dissolve. If not stirred for enough time and/or with a high shear mixer, they can create lumps or aggregates in the paste and, after preparation, it may be necessary to sieve the paste in order to eliminate impurities and aggregates, with a consequent loss of active material.

In addition, the exact dosing and in-loading of the powdery additives, which have usually different densities, different particle sizes and solubility, can be the source of further difficulties.

A typical solution to these problems commonly used in many fields is to granulate the powdery compounds or compositions. Unfortunately the granules obtained during the granulation process are different in their forms and dimensions, thus making it necessary to sieve the granulated material, for the purpose of selecting the granules presenting dimensions above a minimum value. Moreover granulation does not eliminate dust. In fact, a percentage of this dust, even if small, remains embedded in between the granules and tends to spread around . It has been now found that shaped solid additives for reactive dye printing comprising a mixture of a thickener and at least another auxiliary for reactive dye printing can be advantageously used for the preparation of printing paste.

The composition and dimensions of the shaped solid printing additive can be easily controlled in order to avoid hazards and to optimize processing, handling/shipping, in-line dosing, etc. At the same time these shaped solids are really compact, do not produce dust when handled and have a better dispersibility than powders, reducing significantly the formation of lumps in the printing paste.

By "shaped solid" is meant a body in solid form with defined and uniform dimensions which retains its shape after manufacture and during transport and storage, including, but not limited to, pellets, tablets, pearls, flakes, briquettes, or bars.

DESCRIPTION OF TH E INVENTION

It is therefore a fundamental object of the present invention a method of preparing a textile printing paste comprising the following steps:

I) providing a shaped solid additive for textile printing comprising :

a) from 30 to 90 % by weight (% wt) as dry matter of at least one thickener for aqueous systems;

b) from 10 to 70 % by weight as dry matter of an auxiliary for reactive dye printing selected in the group consisting of bases, hydrotropes, reduction inhibitors, wetting agents, emulsifiers, dispersing agents, sequestrants (water softeners), defoamers and mixtures thereof;

II) dissolving in water at least one reactive dye and from 1 to 10 % wt, preferably from 2 to 8 % wt, of said shaped solid additive, based on the total weight of the paste.

It is another object of the present invention a shaped solid additive for textile printing comprising :

a) from 30 to 90 % by weight as dry matter of mixture of thickeners for aqueous systems, said mixture comprising : al) from 20 to 70 % wt as dry matter of a carboxymethyl cellulose, having a DS of from 1.6 to 3.0, based on the total weight of the additive;

a2) from 10 to 55 % wt as dry matter of a product of polymerization of ethylenically unsaturated monomers, based on the total weight of the additive;

a3) from 0 to 35 % wt as dry matter of at least one natural gum or derivative thereof, based on the total weight of the additive;

b) from 10 to 70 % by weight as dry matter of an auxiliary for reactive dye printing selected in the group consisting of bases, hydrotropes, reduction inhibitors, wetting agents, emulsifiers, dispersing agents, sequestrants (water softeners), defoamers and mixtures thereof.

DETAILED DESCRIPTION OF THE INVENTION

Preferably, the shaped solid additive of the method of the invention comprises:

a) from 45 to 80 % wt, more preferably from 55 to 75 % wt, as dry matter of at least one thickener for aqueous systems ;

b) from 20 to 50 % wt, more preferably from 25 to 45 % wt, as dry matter of said auxiliary for reactive dye printing.

The thickener for aqueous systems suitable for the realization of the present invention can be chosen is chosen among natural, semisynthetic and synthetic water soluble polymers and among mixture thereof commonly used in the field and known to those expert in the art, and among mixture thereof.

The natural and semisynthetic water soluble polymers, which can be used for the realization of the present invention, are, for example, natural gums and their derivatives. Specific examples include: alginates; cellulose derivatives, such as carboxymethyl cellulose and hydroxyalkyl cellulose; starch and starch derivatives, such as carboxymethyl starch; galactomannan gums and galactomannan gum derivatives, such as guar gum and guar gum derivatives, for example carboxymethyl guar and hydroxypropyl guar; xyloglucans and xyloglucan derivatives, such as tamarind gum and its derivatives; xanthan gum, arabic gum, tragacanth gum, and mixture thereof.

The thickener can be, for example, an alginate. Suitable alginates are especially alkali alginates of high, medium or low viscosity. Sodium alginate is particularly preferred.

A carboxymethyl cellulose, with a degree of substitution (DS) comprised between 0.6 and 3.0, is also suitable for the realization of the present invention.

In the present disclosure, the expression "degree of substitution" means the average number of carboxymethyl groups for each anhydroglycosidic unit of a polysaccharide and can be determined, for example, according to the standard method ASTM D1439 or by 1H-NMR.

The carboxymethyl cellulose of the present invention can be a technical or purified carboxymethyl cellulose, having a percentage of active substance comprised between 50 and 99.5% by weight on dry matter, preferably between 50 and 80 % by weight, and a moisture content up to 16 % by weight. Preferably, the carboxymethyl cellulose is a technical carboxymethyl cellulose.

The preferred carboxymethyl cellulose has a DS comprised between 1.6 and 3.0, preferably between 1.7 and 2.4 and more preferably between 1.9 and 2.2. Moreover it shows a Brookfield LVT® viscosity, at 2 % wt in water, 60 rpm and 20 °C, comprised between 200 and 5000 mPa_*s, preferably between 500 and 2000 mPa_*s.

The carboxymethyl cellulose with a DS comprised between 1.6 and 3.0 can be prepared by a multiple step reaction of an alkali cellulose with monochloroacetic acid or, for example, with the etherification processes described in US 4,426,206 or US 5,463,036 or any other etherification process known in the art.

An alternative thickener is carboxymethyl starch, having a DS comprised between 0.1 and 1.0 and a Brookfield LVT® viscosity at 8% wt in water, 20 rpm and 20 °C, comprised between 10,000 and 40,000 mPa_*s. Hydroxypropyl guar having a molar substitution (MS) comprised between 0.2 and 1.5 or carboxymethyl guar having a DS comprised between 0.1 and 1.0 are other suitable thickeners.

In the present disclosure, with the expression "molar substitution", we mean the average number of hydroxyalkyl substituents on each anhydroglycosidic unit of the polysaccharide measured by means of ¹H- NMR.

According to the present invention, said thickener for aqueous system can be also a synthetic polymer, preferably a product of polymerization of an ethylenically unsaturated monomer. Preferably, the synthetic polymer is a product of polymerization of an ethylenically unsaturated anionic monomer and/or of an ethylenically unsaturated nonionic monomer, optionally in the presence of a crosslinking agent.

The anionic monomer can be selected among ethylenically unsaturated mono- or di-carboxylic acids or salts thereof or anhydrides thereof, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; and among sulfonic acids or salts thereof, such as 2- acrylamido-2-methyl propane sulfonic acid (AMPS), vinyl sulfonic acid, 2- sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3- sulfopropyl methacrylate, styrene sulfonic acid, 2-propene-l-sulfonic acid, and mixtures thereof. Preferably, the anionic monomer is selected among acrylic acid, 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and mixtures thereof.

Suitable nonionic monomers include ethylenically unsaturated amides, (meth)acrylic Ci-C₆ alkyl esters, substituted or unsubstituted with hydroxy or amino groups, ethylenically unsaturated alcohols and their esters, styrene and substituted styrenes, and vinyl monomers. Specific examples are acrylamide, methacrylamide, N-alkyl acrylamide, N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide, methyl acrylate, ethyl acrylate, 2- ethylhexyl acrylate, n-propyl acrylate, iso-propyl acrylate, butyl acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, vinyl alcohol, allyl alcohol, vinyl acetate, vinyl butyrate, vinyl chloride and the like. Preferably, the nonionic monomer is acrylamide.

In one embodiment, the synthetic polymer of the invention is obtained by polymerization of from 30 to 100 % by moles of an ethylenically unsaturated anionic monomer.

The synthetic polymer of the invention can also comprise a crosslinking agent, for example a compound having at least two ethylenically unsaturated groups. The crosslinking agent can be selected in the group comprising Ν,Ν'-methylene bisacrylamide (MBA), ethylene glycol diacrylate, polyethylene glycol dimethacrylate, diacrylamide, triallylamine, cyanomethylacrylate, vinyl oxyethylacrylate or methacrylate, compounds of the glycidyl ether type such as ethyleneglycol diglycidyl ether, or the epoxydes. Preferably, the crosslinking agent is N,N'-methylene bisacrylamide.

The thickener for aqueous systems obtained by polymerization of a ethylenically unsaturated monomer of the present invention is characterized by a Brookfield LVT® viscosity, at 0.25 % wt in water, 60 rpm and 20 °C, comprised between 10 and 600 mPa_*s, preferably between 200 and 400 mPa_*s.

Mixtures of two or more natural, semisynthetic and synthetic water soluble polymers are especially useful as component a) for the realization of the present invention.

The auxiliary for reactive dye printing b) is chosen in the group consisting of bases, hydrotropes, reduction inhibitors, wetting agents, emulsifiers, dispersing agents, sequestrants (water softeners), defoamers or mixtures thereof.

Suitable base can be, for example, sodium carbonate, sodium hydroxide, disodium phosphate, trisodium phosphate, sodium acetate, sodium propionate, sodium bicarbonate, and aqueous ammonia. Also the equivalent potassium salts can be used . Sodium bicarbonate and sodium carbonate are the preferred bases.

Examples of useful hydrotropes are those capable of solubilizing dyes and include polyhydric alcohols such as propylene glycol, ethylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycols, thiodiethylene glycol and glycerol; amino alcohols such as mono-, di- and tri-ethanolamines; glycerol acetate; ethers such as diethylene glycol monoethyl ether and triglycol ethyl ether; urea, and mixtures thereof. Such auxiliaries are also termed dye solubilizers. Preferably, the hydrotrope is chosen among glycerol, polyethylene glycols, urea and mixture thereof. Of these, the most preferable to use in this invention are glycerol, polyethylene glycols and mixture thereof.

In an especially preferred embodiment of the invention, the shaped solid additive contain from 0 to 10 % wt as dry matter, preferably from 0 to 5 % wt as dry matter, more preferably from 0 to 1 % wt as dry matter of urea.

Suitable reduction inhibitors (anti-reduction agents) include, for example, aromatic nitrocompounds, especially salts of aromatic mono- or di- nitrocarboxylic acids or sulfonic acids, especially alkali metal salts of a nitrobenzenesulfonic acid, e.g . sodium 3-nitrobenzene sulfonate.

Wetting agents and emulsifiers, useful for the preparation of the shaped solid additive, can be anionic or nonionic. Examples of these are: reaction products of aliphatic, araliphatic or aromatic hydroxy compounds, carboxylic acids, carboxylic acid amides or amines with ethylene oxide; sulfuric acid half esters or phosphoric acid partial esters thereof; fatty acid esters of mono- or polysaccharides or fatty acid sorbitan esters and ethoxylation products thereof; Ci₀-C₂o alkanesulfonates, C₈-Ci₂ alkylbenzene-sulfonates; C₈-Ci₈ alkyl sulfates or phosphates; or condensed aromatic sulfonic acids, such as naphthalene-formaldehyde- sulfonates. Substances of the type mentioned can also serve as leveling agents.

Suitable dispersing agents are, for example, the alkali metal or ammonium salts of ligninsulfonic acids, preferably the sodium salts, furthermore condensation products of naphthalenesulfonic acids with formaldehyde, condensation products of phenols or cresols with formaldehyde and sodium bisulfate. Suitable chelating agents (water softeners) are typically sodium nitrilotriacetate, sodium ethylenediaminetetraacetate, sodium polymetha phosphates, such as sodium hexamethaphosphate, and mixtures thereof. Defoamers are, for example, compositions comprising vegetable oils or silicone oils or, in particular, propylene oxide/ethylene oxide block polymers.

Other ingredients that can be advantageously added to the said shaped solid additives for textile printing are fillers; disintegrating agents such as polyvinylpyrrolidones, dextrans, maltodextrins, microcrystalline cellulose, cross-carmellose and starches or mixtures of carboxylic acids, for example citric or tartaric acid, plasticizers such as ethyl cellulose and polyethylene glycol.

The shaped solid additive of the invention can also comprise, as component b), a mixture of auxiliaries for reactive dye printing .

In a particularly preferred embodiment, the shaped solid additive comprises:

a) from 45 to 80 % by weight as dry matter of a mixture of thickeners for aqueous systems, said mixture comprising :

al) from 25 to 45 % wt as dry matter of a CMC, having a DS of from 1.6 to 3.0, based on the total weight of the additive;

a2) from 10 to 30 % wt as dry matter of a product of polymerization of an ethylenically unsaturated monomer, based on the total weight of the additive;

a3) from 10 to 25 % wt as dry matter of at least one natural gum or derivative thereof, based on the total weight of the additive;

b) from 20 to 55 % by weight as dry matter of a mixture of auxiliaries for reactive dye printing, said mixture comprising :

bl) from 1 to 10 % wt as dry matter of a base, based on the total weight of the additive;

b2) from 10 to 20 % wt as dry matter of a reduction inhibitor, based on the total weight of the additive;

b3) from 9 to 25 % wt as dry matter of a hydrotrope, based on the total weight of the additive.

Generally, the shaped solid additive of the invention has dimensions ranging from 0.2 to 100 mm, preferably from 0.5 to 50 mm, more preferably from 0.5 to 30 mm.

The shaped solid additives for textile printing of the invention can be made using a variety of known shaping technologies. The shaped additives can be made by compression processes, the use of molten binding agents, and other processes well known to the person skilled in the art.

The compression processes are preferred and, usually, comprise the following phases:

I. mixing in the appropriate amounts at least one thickener and an auxiliary for reactive dye printing chosen among those mentioned above and, optionally, water, to form a mixture;

II. exerting sufficient pressure on the mixture to form a shaped solid additive for textile printing;

III. optionally, further comminuting the shaped solid body to form a comminuted shaped solid additive for textile printing.

The mixing step (phase I) is performed by conventional means in a manner sufficient to preferably provide a uniform mixture of the starting materials typically under atmospheric pressure and ambient temperature. The optional water addition to the mixture is only important in that it should be high enough to allow the intimate and uniform mixing of the different components and should give a good plasticity to the mixture. Conversely, the water content of the mixture should not be so high that it does not maintain its shape after it is compressed. Generally, the water content of the mixture is from 5.0 to 50 % by weight.

The thus prepared mixture is shaped into a solid body (phase II) by compression processes such as dry pressing or extrusion, preferably by extrusion.

In shaping by dry pressing, the pressure for forming a solid body is typically in a range from about 40 to 140 MPa, and the temperature is typically ambient.

In shaping by extrusion, the mixture, preferably hydrated, is knead in a typical kneader of appropriate size and then extruded. Usually the mixture is heated to or maintained at a temperature in the range from about 20 to about 100 °C. The optimum temperature for extrusion will vary somewhat dependent upon the components of the mixture, but the optimum temperature can readily be determined empirically. The temperature of the mixture may vary depending upon where it is in the extruder, but generally a uniform temperature profile is preferred . The temperature referred to herein is the mixture temperature in the extruder just before it passes through the die. High temperatures which can cause decomposition should be avoided .

The mixture is extruded through a die, preferably a multi-hole die. In general, the shape and size of the orifices fix the cross-sectional shape and size of the extrudate. Although any shape of orifice may be used, i.e. circle, triangle, square, rectangle and star, it is preferred that the extrusion of the mixture is through equiaxial orifices. Equiaxial orifices are orifices that have approximately equal dimensions in all directions. The cross-sectional area of the orifices should be small enough so that the extruded mixture fibers line up parallel to each other in a tightly formed filaments (strands) . On the other hand, the cross-sectional area of the orifice should not be so small that an excessive amount of energy must be exerted to press the mixture through the orifices. Generally, the orifices are of dimensions ranging from 1.0 to 6.0 mm, preferably from 2.0 to 3.5 mm.

The extrusion can be done with any device that applies sufficient pressure to push the mixture through the extrusion orifices at a temperature not too high. For example, a pump-type extruder, such as a positive displacement piston or a gear pump, can be used. Another example of suitable extrusion equipment is a screw-type extruder which advances the mixture by means of a screw rotating inside a cylinder. A twin screw extruder in co-rotating or counter-rotating mode, intermeshing or non- intermeshing may be utilized in the processes of the invention, but equally a single screw extruder or a multi screw extruder may also be suitable providing always that mixing can be achieved .

Usually the extrusion process is carried out at pressures well above atmospheric pressure, preferably the extrusion is carried out at pressures of from about 0.5 to about 16 MPa. The extruded additive of the invention is a firm material appearing uniform in texture and color. Generally, the additive is provided in the form of long, narrow filaments. The filaments have a uniform cross-sectional area that is approximately the same as the extrusion orifices described above.

Typically, the extruded additive has a residual moisture content ranging from 5.0 to 50 % by weight, preferably from 15 to 30 % by weight.

The shaped bodies obtained from phase II, such as extruded filaments, can be further comminuted in order to reduce/optimize their dimensions (phase III).

The comminuting can be accomplished by using standard equipment known in the art. Typical comminuting devices are air-swept impact mills, ball mills, hammer mills, and disk mills. This is preferably done in an air- swept impact mill because the other mills, i.e. ball mills, have a tendency to overmill the product into fine particles that are dusty. In addition, an air-swept impact mill will dry the extruded material, if necessary, by blowing hot air across the mill.

Another method for comminuting the shaped bodies is to cut it with a die- faced cutter. A die-face cutter operates by moving a blade across a stationary die or by moving a die across the stationary blade. Thus, the extruded additive is cut as it come out through the plurality of orifices in the die.

The size of the orifice fix two of the dimensions of the product. Therefore, it is only necessary to cut the filaments to shorten the length. Typically, the extruded inhibitor is cut to a length/diameter ratio of from 0.2 to 3, preferably to a length/diameter ratio of from 1 to 2. It may be advantageous to dry the shaped solid additives for textile printing obtained from the described processes. The drying of the these materials can be accomplished with standard drying equipment and methods known in the art. Typical driers include those commonly used in the art, for example belt driers and fluid bed driers. Typically the shaped solid additive have a residual moisture content generally ranging from 1.0 to 20 % by weight.

According to the method of the invention, the disclosed shaped solid additives are utilized for the preparation of paste comprising reactive dyes useful for printing textile materials.

The shaped solid additives for reactive dye printing disclosed in the preceding paragraphs can be present in an amount of 1 to 10 % wt, based on the total weight of the pastes.

The paste for textile printing of the invention also include at least one reactive dye.

The reactive dye can be a reactive dye customarily used for printing cellulosic fiber materials, chosen among, for example, those described in the Color Index, 3rd edition (1971) and supplements thereto.

Preference is given to the use of dyes of the monoazo, diazo, polyazo, metal complex azo, anthraquinone, phthalocyanine, formazan and dioxazine series which contain at least one reactive group.

These reactive groups are fiber-reactive radicals capable of reacting with the hydroxyl groups of cellulose. They are generally attached directly or via a bridge member to the dye residue. Suitable reactive groups include for example those containing at least one detachable substituent on an aliphatic, aromatic or heterocyclic radical or in which the radicals mentioned contain a radical, for example a halotriazinyl, halopyrimidinyl or vinyl, suitable for reaction with the fiber material.

Examples of suitable aliphatic reactive groups are those of formulae -S0₂- Y, -S0₂-NH-Y, -NH-CO-alk-S0₂-Y, -CO-NH-alk-S0₂-Y, or -NH-CO-Yi, where Y is a leaving group, for example β-sulfatoethyl, β-thiosulfatoethyl, β-phosphatoethyl, β-acyloxyethyl, β-haloethyl or vinyl, Yi is for example an α,β-dihaloethyl or a-haloethenyl radical, alk is Ci-C₆ alkylene; halogen is preferably chlorine or bromine.

Examples of heterocyclic fibre-reactive radicals are 1,3,5-triazine radicals substituted with fluorine, chlorine or carboxypyridinium.

Vinylsulfonyl, chlorotriazine and fluorotriazine are the preferred reactive groups.

Preferably, the textile printing paste comprises from 0.1 to 15 % by weight, more preferably from 0.2 to 10 % by weight, of at least one reactive dye.

The textile printing paste can be prepared by slowly adding the shaped solid additive to water, under mechanical stirring, until complete dissolution is achieved, and subsequently adding other optional auxiliaries and the reactive dye to the thickened solution.

In a preferred embodiment of the invention, the paste for textile printing contains from 0 to 20 % by weight of urea, preferably from 0 to 10 % by weight, more preferably from 0 to 5 % by weight, based on the total weight of the paste.

Typically, the paste for textile printing according to the invention has a Brookfield® RTV viscosity of from 3000 to 15000 mPa_*s, measured at 20 rpm and 20 °C.

The textile printing paste of the invention can be used in any printing process of textile materials and with any textile printing techniques known in the art, for example intaglio, rotary and flat screen printing, hand printing, airbrush printing, etc.

Textile materials which can be printed using the pastes according to the invention are fiber materials of loose fibers, woven or knitted goods or those in the form of nonwovens, based on cellulosic materials or silk. Examples of cellulosic materials are cotton, linen or hemp, or regenerated cellulosic materials such as, for example, viscose, polynosic or cupro, or cellulosic blend materials such as, for example, cotton/polyester materials. To demonstrate the advantages and uses of the shaped solid additives of the present invention, printing pastes were made with exemplary shaped solid additives, evaluating the rheologic behaviour of the paste and, when printed on a substrate, the printability and color yield .

EXAMPLES

In the Examples the following thickener were used :

Table 1

* LVT Brookfield viscosity in mPa_*s in water solution at 20 °C and 60 rpm .

** RVT Brookfield viscosity in mPa_*s in water solution with 10 g/L of Sodium Hexametaphosphate at 20 °C and 20 rpm.

*** RVT Brookfield viscosity in mPa_*s in water solution at 20 °C and 20 rpm .

Examples 1 -9

The ingredients reported in Table 2 were homogenized in a mixer, using a "K" shaped stirrer, after the addition of about 20% by weight of demineralized water, based on the total weight of each mixture.

Table 2

CMA 10 10 - - 11 8.4 4 19 20

CMC1 17 - - 15 - - - - -

CMC2 31 32 35 - 34 28.4 18 34 -

HPG - - - - - - - - 30

UREA - - - - - - 25 - -

PEG 200** 5 0.5 0.5 7.1 0.6 0.8

Glycerol 5 0.5 0.5 7.1 0.6 0.8

Sodium 3-Nitrobenzene Sulfonate

** Polyethylene glycol with a molecular weight of 200.

The moisturized mixtures were fed into a laboratory Bausano TR80® extruder equipped with 2 counter rotating screws, a multi-hole die with holes with a diameter of 2.5 mm and a die-faced cutter.

The speed of the screws and the cutter was adjusted to produce about 50-80 g/min of pellets about 2.5 mm large and 2.6 mm long . The internal temperature and pressure during extrusion were around 60-70 °C and 13 MPa respectively.

All the mixtures of Examples 1-9 were easily extruded and the obtained pellets were dried on fluid bed at 80 °C to obtain a residual moisture in the range from 7 to 12 % wt.

Mechanical Stress test

The stability of the extruded pellets of Examples 1-9 to a strong mechanical stress was evaluated by shaking 50 g of pellets for 30 min in a tared stainless steel sieve (80 mesh) in the presence of 100 g of alumina spheres (2 cm o.d.). For the shaking, a vibratory sieve shaker Retsch AS 200 Basic was used.

At the end of the test the amount of powder which pass through the 80 mesh sieve was determined. For each sample the amount of powder was below 1.0% wt. In particular, for the pellets of Examples 1, 4 and 5, the amount of powder was below 0.3 % wt.

Textile Printing Test

Standard textile printing pastes prepared with the shaped solid additives of Examples 1-9 and two reactive dyes (C.I. Reactive Blue 72 and C.I. Reactive Red 218) showed a rheological behavior and performances (printability and color yield) comparable to those prepared with the single ingredients.

Claims

1) Method of preparing a textile printing paste comprising the following steps:

I) providing a shaped solid additive for textile printing comprising : a) from 30 to 90 % by weight (% wt) as dry matter of at least one thickener for aqueous systems;

b) from 10 to 70 % by weight as dry matter of an auxiliary for reactive dye printing selected in the group consisting bases, hydrotropes, reduction inhibitors, wetting agents, emulsifiers, dispersing agents, sequestrants (water softeners), defoamers and mixtures thereof.

2) The method of Claim 1), wherein said shaped solid additive comprises:

a) from 45 to 80 % wt as dry matter of at least one thickener for aqueous systems;

b) from 20 to 55 % wt as dry matter of said auxiliary for reactive dye printing .

3) The method of Claim 1), wherein said thickener for aqueous systems is chosen is chosen among natural, semisynthetic and synthetic water soluble polymers and among mixture thereof.

4) The method of Claim 3), wherein said thickener for aqueous systems is a semisynthetic water soluble polymers and is a carboxymethyl cellulose with a degree of substitution (DS) comprised between 0.6 and 3.0.

5) The method of Claim 4), wherein said carboxymethyl cellulose has a DS comprised between 1.6 and 3.0.

6) The method of Claim 3), wherein said thickener for aqueous systems is a synthetic water soluble polymers and is a product of polymerization of an ethylenically unsaturated monomer. 7) The method of Claim 3), wherein said thickener for aqueous systems is a mixture of two or more natural, semisynthetic and synthetic water soluble polymers.

8) The method of Claim 1), wherein said shaped solid additive is prepared by extrusion.

9) Shaped solid additive for textile printing comprising :

a) from 30 to 90 % by weight as dry matter of mixture of thickeners for aqueous systems, said mixture comprising :

al) from 20 to 70 % wt as dry matter of a CMC, having a DS of from 1.6 to 3.0, based on the total weight of the additive; a2) from 10 to 55 % wt as dry matter of a product of polymerization of an ethylenically unsaturated monomer, based on the total weight of the additive;

10) The shaped solid additive of claim 9) comprising :

a) from 45 to 80 % by weight (% wt) as dry matter of mixture of thickeners for aqueous systems, said mixture comprising :

al) from 25 to 45 % wt as dry matter of a CMC, having a DS of from 1.6 to 3.0, based on the total weight of the additive; a2) from 10 to 30 % wt as dry matter of a product of polymerization of an ethylenically unsaturated monomer, based on the total weight of the additive;

a3) from 10 to 25 % wt as dry matter of at least one natural gum or derivative thereof, based on the total weight of the additive; from 20 to 55 % by weight as dry matter of a mixture of auxiliaries for reactive dye printing, said mixture comprising :