COMPOSITION FOR PRINTING FIBROUS MATERIALS

Description

Technical field of the invention

[0001] The present invention concerns a composition for treating fibrous materials, in particular for the printing thereof.

[0002] More precisely, the invention concerns a composition for:

• preparation of preprint textile substrates;
• preparation of printing paste;
• formulation of inks;

in processes relative to rotary or flat screen printing and inkjet printing.

Known art

[0003] It is known that in the preparation of paste for printing textile through both silk screen printing, such as rotary or flat screen printing, and inkjet digital printing, it is essential to use urea and, more rarely, some derivatives thereof.

[0004] It is known that urea results in a very high pollutant load in the waste water due to its low biodegradability. Said low biodegradability is due to the hydrolysis reaction of the urea which occurs in a first step with the formation of ammonium cyanate; in a second step, the ammonium cyanate decomposes into ammonia and carbonic acid. Said reaction is far to the left, namely towards the first step, and this results in having persistent quantities of urea and ammonium cyanate with consequent high nitrogen load and presence of quaternary ammonium which is toxic for aquatic organisms. ECHA datum for biodegradability rate of urea: 15.5% after 28 days.

[0005] The need is therefore felt to propose alternative compositions completely replacing the urea and its derivatives.

[0006] It is also known that the alternatives proposed so far have entailed an unacceptable lowering of the colour rendering in addition to a tonal shift differentiated according to the dye and the relative concentration.

[0007] An in-depth non-obvious study has been necessary to find highly biodegradable non-toxic substituents that fully substitute the various intrinsic properties of urea in relation to the complex chemical/physical system that governs the printing process together with some points which are still scientifically obscure concerning the mechanisms of interaction. It is clear that the set of these different properties of urea are at the basis of the quality results guaranteed by urea and not achieved with the current alternatives, but said intrinsic properties of urea also make it difficult to substitute.

Brief summary of the invention

[0008] The object of the present invention is therefore to propose a composition that solves the above-mentioned problem and provides an alternative to urea and to its intrinsic properties for printing textile through both silk screen printing processes, such as rotary or flat screen printing, and inkjet digital printing, which has the following characteristics:

• maintenance of quality standards
• significant reduction in environmental impact
• high eco-toxicological profile
• saving in energy and water resources

[0009] A further object of the invention is to provide a composition that can be used in textile print through both silk screen printing, such as rotary or flat screen printing, and inkjet digital printing, with all classes of reactive dyes and with all classes of acid dyes (which are the most commonly used on the market), and with other categories of dyes requiring the use of urea.

[0010] These and other objects are achieved by a composition for printing fibrous materials, both rotary or flat screen printing and inkjet digital printing, according to claim 1.

[0011] The dependent claims define possible and advantageous embodiments of the invention.

Disclosure of embodiments of the invention

[0012] According to the invention, the composition for use in textile print through both silk screen printing, such as rotary or flat screen printing, and inkjet digital printing, comprises at least one hydrotropic substance which is not urea or a derivative thereof. This provides a composition with low environmental impact, since by eliminating the use of urea, the behaviour resulting from hydrolysis of the urea is avoided, namely persistence in the waste water of undissociated urea and ammonium cyanate, relative quaternized ammonium and high nitrogen load.

[0013] Hydrotropic substances that can be used in the present invention are benzoic acid, brompheniramine maleate, chlorpheniramine maleate, nicotinamide and derivatives thereof, nipecotamide, N-dimethylacetamide, N-methyl-nicotinamide, N,N-dimethyl-nicotinamide, m-hydroxybenzoic acid, p-hydroxybenzoic acid, pheniramine maleate, pyrogallol, resorcinol, penicillin potassium salt, salicylic acid, sodium hydroxybenzoate, sodium ascorbate, sodium benzoate, sodium gentisate, sodium glycinate, sodium salicylate, ibuprofen sodium salt, sodium m-hydroxybenzoate, sodium p-hydroxybenzoate, 4-sulfonic calix[n]arenes, cumene sulphonate, alkylbenzenesulphonates, butyl monoglycol sulphate, picolinamide, isonicotinamide, nicotinic acid, picolinic acid, isonicotinic acid, toluene sulphonate and xylene sulphonate.

[0014] Preferably the hydrotropic substance is selected between cumene sulphonate, xylene sulphonate and nicotinamide. These compounds have a high biodegradability, 99.8%, 87% and 95% respectively after 28 days, and are in fact considered readily biodegradable. Furthermore, the cumene sulphonate and the xylene sulphonate have the advantage of being inexpensive. Nicotinamide has the advantage of having another function in the composition, which will be described below.

[0015] The mechanisms responsible for the hydrotropic solubilization are a function of the nature of the substance to be solubilized, and therefore is selective. In view of this selectivity, it is particularly advantageous for the composition to comprise a mixture of two or more hydrotropic substances.

[0016] It has been found that mixtures of hydrotropic substances in combination produce synergic effects in terms of increased solubility of substances having poor solubility and allow reduction of the quantities of hydrotropic substances to be used. The use of lower quantities of hydrotropic substances benefits both the eco-toxicological aspect and the economic aspect of the composition.

[0017] According to a possible embodiment, the composition also comprises a hygroscopic substance, preferably chosen from ε-caprolactam and hygroscopic salts, or a mixture thereof. The ε-caprolactam is particularly preferable since, in addition to its high biodegradability (96% after 28 days), it also has hydrotrope properties.

[0018] It should be noted that the ε-caprolactam has a great hygroscopic capacity at temperatures typically ranging between 0 and 40°C, while the hygroscopic salts have a great hygroscopic capacity at higher temperatures, typically between 40 and 150°C. It is therefore particularly advantageous for the composition to comprise a mixture of ε-caprolactam with at least one hygroscopic salt, so as to have a high hygroscopic activity over a wide temperature range.

[0019] According to a possible embodiment, independently of the presence of the hygroscopic substance, the composition according to the invention also comprises a substance that swells the fibres; said substance is selected from keratolytic substances, in the case of wool, and cellulolytic substances, in the case of cellulose fibres.

[0020] Of the keratolytic substances, salicylic acid and sodium salicylate, which also have hydrotrope properties, are particularly preferred. Salicylic acid also has excellent biodegradability, 94% in 28 days.

[0021] Of the cellulolytic substances, dimethyl sulfoxide (DMSO), which has a biodegradability of 62% in 21 days, is preferred. DMSO also has the advantage of having excellent solvating properties (synergic action with the hydrotropes), in addition to not being toxic and being resistant to high temperatures, typically 150°C.

[0022] According to another possible embodiment, and regardless of the presence of the hygroscopic substance and/or the fibre-swelling substance, the composition also comprises an aminizing substance, preferably chosen from nicotinamide and nicotinic acid.

[0023] The aminizing substance is useful if a monoreactive monochlorotriazine reactive dye is used for printing fibrous material. The aminizing substance allows hydrolysis of the monoreactive monochlorotriazine reactive dyes to be directed towards the formation of an amine derivative instead of the hydroxytriazine normally obtained. The amine derivative has less affinity with the fibre than the hydroxytriazine, and therefore improves dye wash-off. This improvement in dye wash-off means that the quantity of water to be used for washing the printed textile substrate can be reduced by at least 50%.

[0024] It should be noted that in this situation, the dual function of the nicotinamide previously mentioned is evident, namely hydrotropic character and increase in wash-off via aminization of the monoreactive monochlorotriazine reactive dye during the hydrolysis thereof. This second function occurs only vis-à-vis the monoreactive monochlorotriazine reactive dyes, whereas the hydrotropic function of the nicotinamide occurs with all the classes of reactive and acid dyes.

[0025] It should be underlined that the composition according to the present invention can be used in textile print through both silk screen printing, such as rotary or flat screen printing, and inkjet digital printing. The composition can also be used with all classes of reactive dyes and all classes of acid dyes, extendible to the other categories of dyes requiring the use of urea. Furthermore, as described previously, it is extendible (given its intrinsic properties) also to those printing processes in which urea is not normally used (as with disperse dyes, pigments and indanthrene), with reference also to non-printing application processes that require concentrated impregnation baths (like pad-steam and pad-batch) where the solubilization and permeability of the latter play an important role.

[0026] Note that the use of the composition or parts of the composition can be inserted in the inkjet printing inks, making the use thereof advantageous to reduce and/or eliminate the use of solubilizing substances present in formulation of the inks. Furthermore, given the capacity of the composition to lower the electrical conductivity (a necessary condition for the functioning and life of the print head), glycols can be eliminated in the formulations of the inks.

[0027] Advantageously the hydrotropic substances are present in the composition at a concentration ranging from 0.1 M to 2 M, preferably from 0.2 M to 1 M, even more preferably from 0.4 M to 0.8 M.

[0028] These concentrations of hydrotropic substances provide a good compromise between the solubility of the components to be solubilized (the dyes) and the permeability of the same in the substrate (the fibrous materials). In fact, it has been ascertained that an increase in the solubility of the substance to be carried can cause a reduction in the permeability thereof, especially in the presence of a chemical/physical system in which the substrate shows a hydrophobic or partially hydrophobic character.

[0029] It should also be taken into account that the effect of solubilization varies with the concentration of the hydrotropes. The increase in solubility is linear above a minimum hydrotrope concentration, and said linearity exists up to a maximum concentration of the hydrotrope, beyond which there is no further increase in solubilization. In the same way it has been observed that there is no improvement in the mass transfer coefficient of the solutes beyond the same maximum concentration of the hydrotrope. However, at concentrations near to this maximum concentration value of the hydrotrope, the hydrotropic effect is prevalent in the majority of cases.

[0030] The mode of use of the composition according to the invention varies according to the type of printing in which it is used.

[0031] In textile rotary or flat screen printing, all the components of the composition are mixed together with the printing pastes which contain the dyes. Printing is then carried out with the mixture obtained.

[0032] With inkjet digital printing, on the other hand, there are two alternative possibilities.

[0033] In the first alternative, the composition is applied on the textile substrate (pre-treatment) and the textile substrate is then printed with the printing inks.

[0034] In the second alternative, the printing ink can be formulated by partially integrating the components of the composition therein and subsequently proceeding with the printing.

[0035] Four examples of use of the composition according to the invention are given below.

Example 1

[0036] The composition is used to print a cellulose textile substrate with reactive dyes.

[0037] The solution comprises, as hydrotropic substance, cumene sulphonate or xylene sulphonate or nicotinamide. It is possible to have a mixture of cumene sulphonate or xylene sulphonate with the nicotinamide.

[0038] For better results in terms of solubilization of the dyes and print colour rendering, ε-caprolactam, as hygroscopic substance, and dimethyl sulfoxide, as sweller of the cellulose, can be added to the composition.

[0039] Printing can be carried out by means of traditional printing or digital (inkjet) printing, and fixation can be obtained by means of vaporization or thermofixing.

Example 2

[0040] The composition is used to print a proteic fibrous material, such as silk or wool, with reactive dyes.

[0041] The solution comprises, as hydrotropic substance, cumene sulphonate or xylene sulphonate or nicotinamide. It is possible to have a mixture of cumene sulphonate or xylene sulphonate with the nicotinamide.

[0042] For better results in terms of solubilization of the dyes and print colour rendering, ε-caprolactam, as hygroscopic substance, and sodium salicylate or salicylic acid, as sweller of the proteic fibre, can be added to the composition.

[0043] The printing can be carried out by traditional printing or digital (inkjet) printing, and fixation can be obtained by vaporization or thermofixing.

Example 3

[0044] The composition is used to print a proteic fibrous material, such as silk or wool, with acid dyes.

[0045] The solution comprises, as hydrotropic substance, cumene sulphonate or xylene sulphonate or nicotinamide. It is possible to have a mixture of cumene sulphonate or xylene sulphonate with the nicotinamide.

[0046] For better results in terms of solubilization of the dyes and print colour rendering, ε-caprolactam, as hygroscopic substance, and sodium salicylate or salicylic acid, as sweller of the proteic fibre, can be added to the composition.

[0047] The printing can be carried out by traditional printing or digital (for example inkjet) printing, and fixation is obtained by vaporization.

Example 4

[0048] The composition is used to print an elastan fibrous material with acid dyes.

[0049] The solution comprises, as hydrotropic substance, cumene sulphonate or xylene sulphonate or nicotinamide. It is possible to have a mixture of cumene sulphonate or xylene sulphonate with the nicotinamide.

[0050] For better results in terms of solubilization of the dyes and print colour rendering, ε-caprolactam, as hygroscopic substance, can be added to the composition.

[0051] The printing can be carried out by traditional printing or digital (for example inkjet) printing, and fixation can be obtained by vaporization.

[0052] The composition can be extended to the other categories of dyes requiring the use of urea. It can also be extended (given its intrinsic properties) to classes of dyes such as disperse dyes, pigments and indanthrene used in printing processes where urea is not normally necessary. A further extension also refers to non-printing application processes that require concentrated impregnation baths (like pad-steam and pad-batch) where the solubilization and permeability of the dyes play an important role.

[0053] The intention of the present application is to protect the composition in any overall or partial form as an alternative and decisive solution to urea and its intrinsic properties with reference to the textile processes requiring the use thereof; in fact, the object of the invention is to provide a composition that can be used in textile printing, both rotary or flat screen printing and inkjet digital printing, with all the classes of reactive and acid dyes (which are the most commonly used on the market). The protection of the composition in any overall or partial form with extension to the other categories of dyes in which urea is required. The composition can be used in any overall or partial form with the extension (given its intrinsic properties) also to printing processes where urea is not normally used (as with disperse dyes, pigments and indanthrene), with reference also to non-printing application processes that require concentrated impregnation baths (like pad-steam and pad-batch) where the solubilization and permeability of the latter play an important role.

[0054] The composition in any overall or partial form can be included in the formulation of the printing inks.

[0055] In order to meet specific contingent requirements, a person skilled in the art may make numerous additions or modifications to the described embodiments of the composition for treating fibrous materials according to the invention, or replace elements with other functionally equivalent ones, without departing from the scope of the attached claims.

Claims

1. A composition for printing fibrous materials, comprising at least one hydrotropic substance, excluding urea or a derivative thereof.

2. The composition according to claim 1, comprising at least one hydrotropic substance chosen from the group consisting of benzoic acid, brompheniramine maleate, chlorpheniramine maleate, nicotinamide and derivatives thereof, nipecotamide, N-dimethylacetamide, N-methyl-nicotinamide, N,N-dimethyl-nicotinamide, m-hydroxybenzoic acid, p-hydroxybenzoic acid, pheniramine maleate, pyrogallol, resorcinol, penicillin potassium salt, salicylic acid, sodium hydroxybenzoate, sodium ascorbate, sodium benzoate, sodium gentisate, sodium glycinate, sodium salicylate, ibuprofen sodium salt, sodium m-hydroxybenzoate, sodium p-hydroxybenzoate, 4-sulfonic calix[n]arenes, cumene sulphonate, alkylbenzenesulphonates, butyl monoglycol sulphate, picolinamide, isonicotinamide, nicotinic acid, picolinic acid, isonicotinic acid, toluene sulphonate and xylene sulphonate.

3. The composition according to claim 2, wherein the hydrotropic substance is chosen from cumene sulphonate, xylene sulphonate and nicotinamide.

4. The composition according to claim 1 or 2, comprising a mixture of two or more hydrotropic substances.

5. The composition according to one or more of the preceding claims, also comprising a hygroscopic substance chosen from ε-caprolactam and hygroscopic salts, or a mixture thereof.

6. The composition according to one or more of the preceding claims, also comprising a substance for swelling the fibres chosen from keratolytic substances and cellulolytic substances.

7. The composition according to claim 6, wherein the fibre-swelling substance is chosen from salicylic acid, sodium salicylate and dimethyl sulfoxide.

8. The composition according to one or more of the preceding claims, also comprising an aminizing substance.

9. The composition according to claim 8, wherein the aminizing substance is chosen from nicotinamide and nicotinic acid.

10. A use of the composition according to claim 1 for printing fibrous materials.

11. The use according to claim 10, wherein the printing is followed by a thermofixing step.

12. A paste for rotary or flat screen printing of fibrous materials, comprising the composition according to claim 1.

13. An ink for digital printing of fibrous materials, comprising the composition according to claim 1.

14. A method for printing fibrous materials, comprising the steps of:

a. treating a fibrous material with the composition according to claim 1;

b. printing the fibrous material simultaneously with or subsequently to step a.

15. The method according to claim 14 comprising, subsequently to step b., step:

c. fixing the print by means of thermofixing.