Digital glaze ink

Abstract

The present invention relates to a digital GLAZE ink, to the method for the preparation thereof and to the use of the digital GLAZE ink for functional and/or decorative coating of a ceramic and/or metallic material.

Claims

1. Digital GLAZE ink comprising a solid portion made up of organic and/or inorganic materials, dispersed in a polar and/or aqueous liquid portion wherein: the solid portion is between 10-70% of the total weight of the ink, the solid particle size is less than 40 μm and comprises: at least a flux material, a ceramic raw material or frit at least an anti-settling material the liquid portion comprises: water in a percentage of at least 5% of the total weight of the ink, at least 5% of the total weight of one or more non-aqueous polar solvents additives wherein a solid particle size distribution in percent volume is such that 0.5μm≦d.sub.50≦4.5 μm, 1 μm≦d.sub.90≦11 μm, and 3 μm≦d.sub.100≦40 μm.

2. Digital GLAZE ink according to claim 1, where the flux material, ceramic raw material or frit is at least one element selected from frits, sands, feldspars, aluminas, clays, zirconium silicate, zinc oxide, dolomite, calcite, kaolin, quartz, silica, barium carbonate, wollastonite, tin oxide, nepheline, bismuth oxide, colemanite, calcium carbonate, cerium oxide, cobalt oxide, copper oxide, iron oxide, aluminium phosphate, iron carbonate, manganese oxide, sodium fluoride, chromium oxide, strontium carbonate, lithium carbonate, spodumene, talc, magnesium oxide, cristobalite, rutile, anatase, or mixture thereof.

3. Digital GLAZE ink according to claim 1, where the anti-settling material is selected from carbon black, clay, kaolin, aluminium silicate, carboxymethyl cellulose, bentonite, colloidal magnesium oxide and hydroxide, calcium, strontium, barium, tungsten, zinc, aluminum, silicon, tin and antimony.

4. Digital GLAZE ink according to claim 1, wherein the ink comprises a ceramic pigment selected from natural and/or synthetic coloring oxides.

5. Digital GLAZE ink according to claim 1, where the non-aqueous polar solvents are selected from alcohols, aliphatic fatty alcohols, glycols, polyglycols, glycols esters, glycol ethers, phenols, alkylphenols, fatty acids, terpenes, terpenic alcohols, terpenic oils, and copolymers of vinyl pyrrolidone.

6. Digital GLAZE ink according to claim 1, where the additives are selected from dispersants, rheological modifiers, surfactants, anti-foaming, buffer for pH control, bactericides, fungicides, preservatives.

7. Digital GLAZE ink according to claim 1 wherein the ink has a viscosity ranging between 5-70 cP at the working temperature.

8. Digital GLAZE ink according to claim 1 wherein the ink has a pH ranging between 5-12.

9. Digital GLAZE ink according to claim 1 wherein the ink has a surface tension at room temperature greater than 30 mN/m.

10. Method for the preparation of the digital GLAZE ink according to claim 1 comprising the following steps: a) mixing of the solid raw materials, b) putting in a mill the solids in the step a) together with part of the water, solvents and additives, c) grinding, d) controlling the particle size to ensure that the solid particle size distribution of 0.5 μm≦d.sub.50≦4.5 μm, 1 μm≦d.sub.90≦11 μm, and 3 μm≦d.sub.100≦40 μm in percent volume is obtained, e) adding the rest of the water, solvents and liquid additives, f) discharging the mill by sieving and filtering, g) controlling and adjusting a viscosity.

11. Method according to claim 10, wherein the step c) is carried out for a time ranging between 5-15 hours.

12. Method according to claim 10, wherein the step d) is carried out by laser beam diffraction in wet process.

13. Method according to claim 10, wherein the sieving of the step f) is carried out with a sieve having a pore size of 80 μm and subsequently, the filtering is carried out with a filter having a pore size of 40 μm.

14. Method according to claim 10, wherein the adjustment of the viscosity is carried out by water and/or additives.

15. A method for functionally and/or decoratively coating a material comprising applying the GLAZE ink according to claim 1 to a ceramic and/or metallic material.

16. The method according to claim 15, wherein the GLAZE ink is applied to the ceramic and/or metallic material by a digital ink system.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The high discharge digital GLAZE of the present invention applicable to industrial decoration, are characterized in that the composition contains a solid portion formed by inorganic and organic materials and a liquid aqueous and/or polar portion which are homogenized, and once it is applied on the ceramic support, it is cooked at temperatures between 500° C. and 1300° C.

(2) Ceramic appearance that the inks of the present invention provide ceramic products not only is limited to the fact of coloring the surface ceramic or GLAZE on which are applied, but they give a finish (gloss, matt, roughness, lustre, metallized, embossing, etc) that inks for injection until now do not provide.

(3) With regard to the formulation of high discharge digital GLAZE, the main difference with the current ceramic inks for injection is the use of water in its formulation. Even though the liquid portion will also have another type of polar solvent and/or additives, the water will become part of digital GLAZES, and therefore more respectful with the environment, in percentages greater than 5% of the total weight of the ink.

(4) Non-aqueous polar component of the ink is a mixture of one or more compounds selected from aliphatic fatty alcohols, glycols, polyglycols, glycols esters, glycol ethers, phenols, alkylphenols, fatty acids, terpenes, terpenic alcohols, terpenic oils, and copolymers of vinyl pyrrolidone. Non-aqueous polar component will be part of the ink in percentages greater than 5% of the total weight.

(5) For the formulation of the solid portion, raw materials will be used, which have been used at present for the formulation of ceramic GLAZES that are applied with traditional techniques such as: frits, sands, feldspars, aluminas, clays, zirconium silicate, zinc oxide, dolomite, calcite, clay, kaolin, etc); along with materials that act as anti-settlings: carbon black, clay, kaolin, aluminium silicate, carboxymethyl cellulose, bentonite, colloidal magnesium oxide and hydroxide, calcium, strontium, barium, tungsten, zinc, aluminum, silicon, tin and antimony. The solid portion of the digital GLAZES represents between 10% and 70% by weight, preferably between 20% and 50% by weight depending on the ceramic and material effect required. It is logical that when more layer thickness is necessary, the solid content and the weight applied will be higher.

(6) When the ink is colored, ceramic pigments will be used, mixture of one or more components selected from conventional natural or synthetic coloring oxides.

(7) The particle size of high discharge digital GLAZES of the present invention is greater than that of the current colored ceramic inks for injection, which is sub-micron, but much thinner than the traditional applications, which have a d.sub.100 of 45 μm or higher. Therefore, a step of grinding, in wet or dry process, but preferably in wet process, is required for the preparation of high discharge digital GLAZE. Thicker size within a particle size distribution (d.sub.100, 100% of particles below that value) is from 3 to 40 μm and the size below which is 90% in volume of the particles is from 1 to 11 μm, in addition the particle size distribution must be as narrow as possible. Regarding inkjet inks and GLAZES for DOD heads, a thicker size will allow saving energy and money at the step of grinding of the dispersion of solids and therefore favor the expansion of the technique.

(8) Additives such as dispersants, surfactants, anti-foamings, rheology modifiers, buffer for pH control, bactericides, fungicides, etc. . . . usually used in the preparation of any ink or GLAZE, can be used.

(9) In addition, both the manufacturing process and the chemical composition of high discharge digital GLAZES are economically comparable to conventional inks and totally viable for digital implementation on an industrial scale, in addition they can have a better respect for the environment. However, the main feature of high discharge digital GLAZES is in their physical properties, such as viscosity higher than 5 cP at application temperature and surface tension higher than 30 mN/m, as described below.

(10) The optimum and characteristic physical properties of high discharge digital GLAZES are: Ceramic particle size distribution (% in volume): 0,5 μm≦d.sub.50≦4,5 μm, 1 μm≦d.sub.90≦11 μm and 3 μm≦d.sub.100≦40 μm Viscosity at application temperature (20-40° C.): from 5 to 70 cP Rheological behavior: slightly pseudoplastic. Surface tension at room temperature 30 mN/m Density at 20° C.≦1 g/ml Solid content: between 10 and 70% by weight, preferably between 20 and 50% by weight pH: between 5 and 12 Without hard sedimentation and easily redispersable Completely water-miscible Fully compatible with the materials of the digital printing system.

(11) These high discharge digital GLAZES can be used in digital print heads, described in the patent EP2085225A2, and designed for decorating ceramic products. They can also be used in any type of head, as those described in WO99/46126 and WO2006/027212, or that supports the use of polar and/or aqueous inks with the abovementioned physical properties. On the other hand, they also are specially formulated to be applied on porous supports that can absorb the liquid portion of the inks and such that they develop the desired ceramic effect when are cooked between 500 and 1300° C. However, they can also adapt to be applied on non-porous supports, like glass and metal, incorporating an organic fixer or a volatile solvent(s) below 100° C. so that the digital GLAZE dries quickly before the heat treatment (500 to 800° C.).

(12) These properties cannot be obtained by simple mixing of conventional ceramic products or simple dilution of a conventional ceramic serigraph ink due to the solid content have to be considerably reduced and therefore the effect of thickened would be lost and the suspension would also be unstable during the application due to the coarse of particle size. On the other hand, the optimum physical properties of digital GLAZES would not suitable for a conventional application due to the low viscosity and low pseudo-plasticity.

(13) As with the ceramic pigmented inkjet inks, the digital GLAZE inks are ready to use, because of the numerous advantages for the end user, but in polar base fully compatible with water for easy cleaning of the digital delivery system.

(14) Digital GLAZES can be colored or not with ceramic pigments based on application requirements.

(15) High discharge digital GLAZES of the present invention not only have optimal performance in the printing system but they can also be deposited with weights from between 10 g/m.sup.2 and 3 kg/m.sup.2 and therefore allow obtaining thick layers with the perfect development of the necessary ceramic appearance after cooking cycles at high temperatures between 500 and 1300° C.

EXAMPLE 1

Digital GLAZE Ink

(16) Table 1 shows various examples of digital GLAZE ink of the present invention

(17) TABLE-US-00001 TABLE 1 digital GLAZE ink RAW GLAZES (%) MATERIALS 1 2 3 4 5 6 7 8 Frit 6 10 8 10 10 10 6 6 Kaolin 2 3 6 2.8 3 2.8 4 4 Sodium 8 14.2 10.6 8.4 8.4 feldspar Quartz 18.4 8.6 12.2 8 8 9.2 9.2 Zr silicate 2.0 12 micronized of 5 μm Alumina 3.6 4.2 3.2 3.2 3.2 Wollastonite 8 8 9.2 9.2 Potassium 7.6 7.6 feldspar Dolomite 3.6 3.6 Tin oxide 15 WATER 32.3 38.3 20.7 32.58 20.45 5 32.46 52.38 Monoethylene 25.4 37.0 25.0 37.0 52.5 glycol Diethylene 25 glycol Glycerin 19 5 Anti-foaming 2 2 2 2 2 2 2 2 Dispersant 0.2 0.6 0.2 0.3 0.4 0.4 0.4 0.4 Carboxymethyl 0.08 0.08 0.08 0.1 0.13 0.08 0.12 0.2 cellulose Bactericide 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02

(18) Table 2 shows the physical properties of inks of the present invention

(19) TABLE-US-00002 TABLE 2 Physical properties of inks of the present invention Physical GLAZE GLAZE GLAZE GLAZE GLAZE GLAZE GLAZE GLAZE properties 1 2 3 4 5 6 7 8 CS (%) 40 40 40 40 40 40 40 40 D50 (μm) 2.7 2.5 2.6 2.6 1.1 2.5 2.6 2.8 D90 (μm) 8.1 7.5 7.8 7.6 4.2 7.6 8.0 8.5 D100 (μm) 20.6 20.6 20.6 20.6 17.4 20.6 20.6 24.6 Density 1.44 1.43 1.43 1.42 1.56 1.45 1.42 1.38 (20° C.) (g/cm.sup.3) Vis (20° C.) 31.0 34.0 27.0 42.3 26.0 (cP) Vis (35° C.) 35.0 34.6 66 (cP) Surface 38 40 36 38 36 38 36 38 tension (mN/m) (25° C.)

EXAMPLE 2

Method for Making the Digital GLAZE Ink of the Present Invention

(20) The general procedure for making the digital GLAZE ink of the present invention comprised the following steps: Mixing the solid raw materials. Putting in the mill the solids with all or part of the water and all or part of the rest of the liquid components of the digital GLAZE (solvents and liquid additives). Grinding in ball mill for a time ranging between 5-15 h, with a ball charge the size distribution of which is specific to obtain the desired particle size. Controlling the particle size by measuring it by means of a equipment of laser beam diffraction in wet process, to verify that the suitable particle size distribution is obtained. Adding the rest of water and liquid components (solvents and liquid additives) not introduced in the initial grinding. Discharging the mill with a material sieving at 80 μm and subsequent filtering at 40 μm to eliminate the possible existence of coarse particles that could produce stoppage and damage the head with which will be GLAZE. Controlling the viscosity to verify that it has the optimum working value, which will be determined by the head that is to be used. Adjustment of this property if necessary by the use of water or additives.

(21) In the specific case of the GLAZE ink 1, the process was as follows: Mixing of the frit, kaolin, sodium feldspar, quartz, zirconium silicate, Alumina, dispersant, carboxymethyl cellulose. Putting in the mill the solids and water (about 75% of total water of the formula). Grinding until achieving a d90≈8 μm measured by laser in wet process Adding the monoethylene glycol, anti-foaming, bactericide and remaining water. Discharging the mill with a material sieving at 80 μm and subsequent filtering at 40 μm. Ensuring that the desired viscosity has been obtained, and adjusting this property if necessary by the use of additives or water.