CERAMIC INK FOR INKJET PRINTING

Abstract

A ceramic ink for inkjet printing, comprising: one or more inorganic pigments, distilled, double-distilled or demineralized water, one or more polar organic solvents, one or more dispersants, one or more antifoaming surfactants and optionally one or more preservatives/bactericidal agents, in defined quantities.

Claims

1-15. (canceled)

16. A ceramic ink for inkjet printing, comprising: (i) 15 to 60% by weight with respect to the total weight of the ink of one or more inorganic pigments; (ii) 5 to 80% by weight with respect to the total weight of the ink of distilled, double-distilled or demineralized water; (iii) 5 to 80% by weight with respect to the total weight of the ink of one or more polar organic solvents selected from the group consisting of glycerol, glycerol ethoxylate with 2 to 20 moles of ethylene oxide per mole of glycerol, monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols with a molecular weight comprised between 200 and 4,000 Da, monopropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycols with a molecular weight comprised between 200 and 4,000 Da, propylene glycol methyl ether and isomers thereof, dipropylene glycol methyl ether and isomers thereof, tripropylene glycol methyl ether and isomers thereof, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, methyl diglycol, methyl triglycol, butyl glycol, butyl diglycol and butyl polyglycol; (iv) 0.1 to 15% by weight with respect to the total weight of the ink of one or more dispersants selected from the group consisting of: polyacrylate polymers and derivatives thereof with a molecular weight comprised between 1000 and 100,000 Da, polyurethane polymers and derivatives thereof, acrylate/maleate copolymers and derivatives thereof with a molecular weight comprised between 1000 and 100,000 Da, resins based on styrene/maleic anhydride (SMA), alkylene polyphosphone esters, phosphoric acid esters, salts of carboxylic or hydrocarboxylic acids and derivatives thereof, esters of carboxylic or hydrocarboxylic acids and derivatives thereof, amide polyesters and derivatives thereof; (v) 0.01 to 1% by weight with respect to the total weight of the ink of one or more antifoaming surfactants selected from the group consisting of: block copolymers of ethylene oxide/propylene oxide, pure and/or emulsified silanes, pure and/or emulsified siloxanes, pure and/or emulsified fatty acids and esters thereof; (vi) 0 to 0.5% by weight with respect to the total weight of the ink of one or more preservatives/bactericidal agents selected from the group consisting of methylisothiazolinone (MIT) and derivatives thereof, chloromethylisothiazolinone (CIT) and derivatives thereof, benzisothiazolinone (BIT) and derivatives thereof, and organic molecules that release formaldehyde.

17. The ceramic ink according to claim 16, wherein said one or more polar organic solvents are selected from the group consisting of polyethylene glycols with a molecular weight comprised between 200 and 800 Da, polypropylene glycols with a molecular weight comprised between 200 and 800 Da, and mixtures thereof.

18. The ceramic ink according to claim 16, wherein said one or more dispersants are selected from the group consisting of polyacrylate polymers, alkylene polyphosphone esters and mixtures thereof.

19. The ceramic ink according to claim 16, wherein said one or more antifoaming surfactants are selected from the group consisting of block copolymers of ethylene oxide/propylene oxide, silanes, siloxanes and mixtures thereof.

20. The ceramic ink according to claim 16, wherein said one or more preservatives/bactericidal agents are selected from the group consisting of methylisothiazolinone (MIT), chloromethylisothiazolinone (CIT) and mixtures thereof.

21. The ceramic ink according to claim 16, wherein said one or more inorganic pigments are present in a total quantity comprised between 25 and 50% by weight with respect to the total weight of the ink.

22. The ceramic ink according to claim 16, wherein the distilled, double-distilled or demineralized water is present in a quantity comprised between 20 and 40% by weight with respect to the total weight of the ink.

23. The ceramic ink according to claim 16, wherein said one or more polar organic solvents are present in a total quantity comprised between 5 and 40% by weight with respect to the total weight of the ink.

24. The ceramic ink according to claim 16, wherein said one or more dispersants are present in a total quantity comprised between 0.1 and 15% by weight with respect to the total weight of the ink.

25. The ceramic ink according to claim 16, wherein said one or more antifoaming surfactants are present in a total quantity comprised between 0.01 and 0.5% by weight with respect to the total weight of the ink.

26. The ceramic ink according to claim 16, wherein said one or more preservatives/bactericidal agents are present in a total quantity comprised between 0.1 and 0.2% by weight with respect to the total weight of the ink.

27. A method for preparing a ceramic ink according to claim 16, comprising the steps of: (a) preparing a mixture of distilled, double-distilled or demineralized water and one or more polar organic solvents selected from the group consisting of glycerol, glycerol ethoxylate with 2 to 20 moles of ethylene oxide per mole of glycerol, monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols with a molecular weight comprised between 200 and 4,000 Da, monopropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycols with a molecular weight comprised between 200 and 4,000 Da, propylene glycol methyl ether and isomers thereof, dipropylene glycol methyl ether and isomers thereof, tripropylene glycol methyl ether and isomers thereof, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, methyl diglycol, methyl triglycol, butyl glycol, butyl diglycol and butyl polyglycol; (b) adding to the mixture obtained in step (a): (i) one or more dispersants selected from the group consisting of: polyacrylate polymers and derivatives thereof with a molecular weight comprised between 1000 and 100,000 Da, polyurethane polymers and derivatives thereof, acrylate/maleate copolymers and derivatives thereof with a molecular weight comprised between 1000 and 100,000 Da, resins based on styrene/maleic anhydride (SMA), alkylene polyphosphone esters, phosphoric acid esters, salts of carboxylic or hydrocarboxylic acids and derivatives thereof, esters of carboxylic or hydrocarboxylic acids and derivatives thereof, amide polyesters and derivatives thereof; (ii) one or more antifoaming surfactants selected from the group consisting of: block copolymers of ethylene oxide/propylene oxide, pure and/or emulsified silanes, pure and/or emulsified siloxanes, pure and/or emulsified fatty acids and esters thereof; and optionally (iii) one or more preservatives/bactericidal agents selected from the group consisting of methylisothiazolinone (MIT) and derivatives thereof, chloromethylisothiazolinone (CIT) and derivatives thereof, benzisothiazolinone (BIT) and derivatives thereof and organic molecules that release formaldehyde; (c) adding to the mixture obtained in step (b) one or more inorganic pigments, obtaining a dispersion; (d) milling the inorganic pigments by treating the dispersion obtained in step (c) with a grinding mill; (e) filtering the dispersion obtained in step (d).

28. Use of a ceramic ink according to claim 16 to decorate a ceramic article by inkjet printing.

29. The use according to claim 28, wherein said ceramic article is selected from the group consisting of tiles, kitchenware and technical ceramics.

30. A ceramic article decorated with a ceramic ink according to claim 16.

Description

EXAMPLES

Example 1: Formulation of a Blue Water-Based Ink

[0061] Components and quantities (by weight with respect to the total weight of the ink):

TABLE-US-00001 Blue pigment (cobalt aluminate spinel)  30% Water  30% Ethylene glycol (mono, di, tri)  19% Polyethylene glycols (MW 200-800) 9.5% Tripropylene glycol methyl ether   6% Polyacrylate polymers—acrylate/maleate copolymers   5% (MW 1000-100,000) Block copolymers of ethylene oxide/propylene 0.3% oxide, silicone surfactants (silanes and siloxanes), fatty acid esters Preservative/bactericidal agent 0.2%

[0062] Physical and rheological parameters:

Density=1360 kg/m.sup.3 at 25° C.;
Viscosity=13.5 mPa*s at the operating temperature of 45° C.;
Surface tension=28*10.sup.−3 N/m at the operating temperature of 45° C.

Example 2: Formulation of a Yellow Water-Based Ink

[0063] Components and quantities (by weight with respect to the total weight of the ink):

TABLE-US-00002 Yellow pigment (zirconium praseodymium)   30% Water   31% Ethylene glycol (mono, di, tri) 17.5% Polyethylene glycols (MW 200-800)   9% Tripropylene glycol methyl ether   7% Polyacrylate polymers—acrylate/maleate copolymers (MW 1000-100,000)   5% Block copolymers of ethylene oxide/propylene  0.3% oxide, silicone surfactants (silanes and siloxanes), fatty acid esters Preservative/bactericidal agent  0.2%

[0064] Physical and rheological parameters:

Density=1380 kg/m.sup.3 at 25° C.;
Viscosity=14.5 mPa*s at the operating temperature of 35° C.;
Surface tension=28.5*10.sup.−3 N/m at the operating temperature of 35° C.

[0065] In practice it has been found that the ceramic ink for inkjet printing according to the invention fully achieves the intended aim, since by being water-based it allows to reduce the organic solvent content. Accordingly, the ink according to the invention is less polluting and more environment-friendly than known inks of the background art, based on organic solvents, as regards its production process, its use and the cleaning of the instruments that come into contact with it. Moreover, the ink described herein achieves the intended aim since it minimizes the water-repellency of the applications of glaze following the ceramic decoration and improves the yield of the colors used for decoration.

[0066] The ceramic ink according to the present invention, the method for preparing it and its use for the decoration of ceramic articles, thus conceived, are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements the correspondence of which is known to the person skilled in the art.

[0067] The disclosures in Italian Patent Application No. MO2014A000269 from which this application claims priority are incorporated herein by reference.