IT8268543A1 - PROCEDURE FOR THE MANUFACTURE OF DECORATED CERAMIC PRODUCTS. - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

'Process for the manufacture of decorated ceramic products'

SUMMARY

Process for the manufacture of glazed ceramic products, decorated using the single-firing technique, by molding together two layers of a ceramic material and a glaze powder, followed by decoration of the glaze layer and firing at 900-1250°C, wherein the glaze powder, prior to molding, is uniformly mixed and/or coated with an aqueous-phase binder consisting of organic polymeric compounds with glass transition temperatures ranging from -50 to 80°C.

The present invention relates to a process for the manufacture of decorated glazed ceramic products, using the single-firing technique, by moulding together two layers of a ceramic material and a glaze powder, with subsequent decoration of the glaze layer and firing at 900-1250°C.

In the manufacture of ceramic products, particularly wall and floor tiles, there is a strong need to rationalize the manufacturing process, driven by increasing costs of raw materials, energy, and personnel (as well as the need for environmentally friendly working methods).

Various processes are used in the manufacture of ceramic wall and floor tiles. Typically, the ceramic glaze, known as green ceramic, is pre-fired in the bisque firing process. This results, depending on the firing temperature and the composition of the ceramic material, in ceramics with varying porosities ranging from 0.2 to 20%, with earthenware averaging 5 to 15% and stoneware averaging 0.2 to 2%.

After cooling, this ceramic is glazed with a wet glaze mixture in the wet application. Optionally, a hardener can be sprayed onto the unfired glaze surface and decorated using direct printing or transfer. This is followed by a second firing—the so-called glazing firing—during which the glazed surface forms. If necessary, the glazed surface can be further modified by decorating with paints, ceramics in the direct printing firing, brush application, or transfer in a third firing, the so-called decorative firing, at 600–800°C. However, these multiple-firing processes are very energy- and personnel-intensive.

An equally popular tile manufacturing method is based on molding a ceramic powder and glazing the unfired green ceramic. This can be done using liquid glazing, for example, spraying or spinning, or by sprinkling dry glazing powder. The finished tile is then obtained in a single firing process. However, this process does not allow for decoration.

Furthermore, the molding of ceramic powder and glaze powder is known, with the glaze being introduced into the mold in a thin layer above or below the ceramic powder. In the subsequent molding process, a tile is obtained that is dried and, after a subsequent single firing, yields the finished tile. However, direct decoration of the tile before firing is not possible. Due to the powdery behavior of the dry-printed glaze surface, in the case of decoration by direct printing, transport, or decalcomania, the adhesion of the decoration layer to the glaze surface is insufficient. In direct printing, for example with decorative paint pastes, the adhesion to the glaze surface is lower than the cohesion of the paste itself, so that the screen does not detach from the printed layer, but the printed layer remains attached to the underside of the screen. Furthermore, such tiles suffer from stability defects at the edges of the glaze.

It is therefore the object of the present invention to find a process for the manufacture of decorated glazed ceramic products (using the single-firing technique, by moulding together two layers of a ceramic material and a glaze powder, with subsequent decoration of the glaze layer and firing at 900-1250°C), which is less expensive in terms of energy and personnel costs, which allows an environmentally friendly way of working, and allows complete decoration of the unfired glaze layer by direct printing, conveying, painting, or the application of decals.

This problem is solved, according to the invention, by mixing and/or uniformly coating the glaze powder, prior to molding, with an aqueous-phase binder consisting of organic polymeric compounds with glass transition temperatures ranging from -50 to 803°C. This forms a decorateable, pressure-stable glaze surface that can be treated with all known decoration processes.

As regards the glass transition temperature, it is a relatively sharp transition point, below the melting point, at which compounds change to the glassy state (DIN 52324).

The binders are found either as a dispersion or as an aqueous solution, the aqueous phase being used mainly for ecological reasons and to save raw materials.

As organic polymer compounds, particularly suitable are substances whose glass transition temperatures are significantly below the molding temperatures used. Substances with a glass transition temperature in the range from ~50°C to 40°C have proven particularly well, as this must be approximately 10 to 90°C below the molding temperature of the ceramic material used, starting from molding temperatures between room temperature and 90°C. In the case of higher molding temperatures, binders with higher glass transition temperatures can also be used, but this leads to other drawbacks.

Binders are added to the glaze powder in quantities of 1 to 15% by weight of the glaze powder, especially in quantities of 4 to 10%, where

of a binder addition/as small as possible.

Are water dispersions, for example, suitable as binders?

if based on vinyl compounds, such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl pivalate, and styrene. Aqueous polymer solutions (for example, solutions of polyvinyl alcohols, polyvinyl ethers, and polyvinylpyrrolidones) are considered.

Aqueous dispersions or aqueous solutions are particularly suitable as binders! Polymers or copolymers based on methacrylic acid and its esters, as well as acrylic acid and its esters. The use of other unsaturated compounds is also possible, which, together with acrylates and methacrylates, are suitable for free-radical copolymerization. Polymers based on acrylates and methacrylates have the advantage, on the one hand, that they depolymerize or burn without residue during the firing process and do not cause any problems in this regard, and on the other hand, that a wide range of acrylic acid and methacrylic acid esters are widely available, which allows the preparation of homopolymers and copolymers with glass transition temperatures preferably between -50°C and 80°C.

Suitable monomers include, for example, methacrylic acid, methacrylic acid methyl ester, methacrylic acid n-butyl ester, methacrylic acid isobutyl ester, methacrylic acid 2-ethylhexyl ester, methacrylic acid lauryl ester, acrylic acid, acrylic acid methyl ester, acrylic acid ethyl ester, acrylic acid n-butyl ester, acrylic acid tert-butyl ester, acrylic acid 2-ethylhexyl ester, and acrylic acid lauryl ester. Other esters of acrylic acid and methacrylic acid can also be used as comonomers.

The acrylate (methacrylate) copolymers mentioned can be used both as an aqueous dispersion and as an aqueous solution and are therefore universally applicable. It is advisable to work with aqueous solutions, especially when small amounts of binder are added, as this allows for a more homogeneous distribution of the glaze particles with the polymer material. The acrylate (methacrylate) copolymers are prepared according to known emulsion polymerization processes and are available as dispersions in the acidic pH range. By introducing sufficient quantities of ionizable acidic groups, such as carboxylic acid groups, these dispersions convert into the corresponding solutions upon neutralization of the acidic groups with alkali or ammonia.

Some examples of advantageous polymeric acrylic and methacrylic acid esters and their preparation are described below.

1. In a 21 cm flask, equipped with a reflux condenser, anchor stirrer, internal thermometer and nitrogen supply tube, prepare:

1,400 ml of H^O (deionized)

6 g of sodium lauryl sulfate

0.2 g of ammonium peroxodisulfate The aqueous solution is heated, under nitrogen, to 35?C. Once this internal temperature is reached, the dosage of a mixture of monomers consisting of

120 g of methacrylic acid methyl ester 360 g of acrylic acid n-butyl ester 120 g of methacrylic acid

0.15 g of ?ter-dodecyl mercaptan.

This monomer mixture is continuously dosed for two hours. The internal temperature is maintained at 85°C during the reaction time. After the dose time, it is stirred for another hour at 85°C. The dispersion is cooled and filtered through a 200-fiber nylon gauze. The coagulate content is less than 1%.

The solids content of the dispersion is 30%. Neutralization with ammonia or alkali transforms the dispersion into a clear solution. The glass transition temperature of the polymer thus prepared is approximately 0°C.

2. In a 21-liter flask, equipped with a reflux condenser, anchor stirrer, internal thermometer and nitrogen supply pipe, prepare:

1.400 ml of ? 0 (deionized)

2

g of sodium lauryl sulfate

0.2 g of ammonium peroxodisulfate.

The aqueous solution is heated to 85°C under nitrogen. Once this internal temperature is reached, the dosage of a mixture of monomers begins, consisting of

240 g of methacrylic acid methyl ester 240 g of acrylic acid n-butyl ester 120 g of methacrylic acid

0.2 g of tert-dodecyl mercaptan.

The monomer mixture is dosed continuously for two hours. The internal temperature is maintained at 853°C during the entire reaction time. After the dosing time, it is stirred for another hour at 35°C. The dispersion is cooled and filtered through a 200-μm nylon gauze. The coagulate content is less than 1%. The solids content of the dispersion is 30%. Neutralization with ammonia or alkali transforms the dispersion into a clear solution.

The glass transition temperature of this polymer is approximately 32°C.

3. In a 21-ball according to example 1, we arrange

1,400 ml of H^0 (deionized)

6 g of sodium lauryl sulfate

0.2 g of ammonium peroxodisulfate.

The aqueous solution is heated to 85°C under nitrogen. Once this internal temperature is reached, the dosage of a monomer mixture consisting of

390 g of methacrylic acid methyl ester 90 g of acrylic acid n-butyl ester 120 g of methacrylic acid

0.1 g of tert-dodecyl mercaptan.

The monomer mixture is dosed continuously for two hours. The internal temperature is maintained at 85°C for the entire reaction time. After the dosing time, it is stirred for another hour at 85°C. The dispersion is cooled and filtered through a 200-micron nylon gauze. The coagulate content is less than 1%. The solids content of the dispersion is 30%. By neutralizing with ammonia or alkali, the dispersion becomes a clear solution.

The glass transition temperature of this polymer is approximately 80°C.

4. In a 21-ball according to example 1, the following are arranged:

1.40.0 ml of H 0.{deionized)

2

6 g of sodium lauryl sulfate

0.2 g of ammonium peroxodisulfate.

The aqueous solution is heated to 85°C under nitrogen. Once this internal temperature is reached, the dosage of a monomer mixture consisting of:

480 g of n-butyl ester of acrylic acid 120 g of methacrylic acid

0.3 g of tert-dodecyl mercaptan.

The monomer mixture is continuously dosed for two hours. The internal temperature is maintained at 35°C during the entire reaction time. After the dosing time, it is stirred for another hour at 35°C. The dispersion is cooled and filtered through a 200-yd nylon gauze. The coagulate content is less than 1%. The solids content of the dispersion is 30%. Neutralization with ammonia or alkali transforms the dispersion into a clear solution. The glass transition temperature is approximately -27°C.

5. In a 21-liter flask, equipped with a reflux condenser, anchor stirrer, internal thermometer and nitrogen supply pipe, prepare:

1,400 ml of H 0 (deionized)

2

6 g of sodium lauryl sulfate

0.2 g of ammonium peroxodisulfate.

The aqueous solution is heated to 35°C under nitrogen. Once this internal temperature is reached, the dosage of a monomer mixture consisting of

450 g of 2-ethylhexyl ester of acrylic acid 150 g of methacrylic acid

0.3 g of tert-dodecyl mercaptan.

The monomer mixture is continuously dosed for two hours. The internal temperature is maintained at 85°C for the entire reaction time. After the dosing time, it is stirred for another hour at 85°C. The dispersion is cooled and filtered through a 200° mesh. The coagulate content is less than 1%. The solids content of the dispersion is 30%.

The glass transition temperature of the polymer is approximately -50°C.

Ceramic products are manufactured in this way: first, a homogeneous mixture of glaze powder and binder is prepared. To this end, the aqueous solution or dispersion of binder and the wet glaze mixture are homogeneously mixed in a container. The amount of binder depends on the type of glaze powder, the molding pressure, and the strength requirements of the glazed surface of the tile. Additions of 1% to 15% binder are normally sufficient for sufficient strength; preferably, additions of 4% to 10% binder are used. The wet glaze mixture containing the binder is then dried, preferably in a spray dryer. However, other mixing methods can also be used, such as a fluidized bed or dry processes. The required homogeneous mixture is always decisive in this case. The glazes used must be compatible (in terms of viscosity) with the firing conditions, so that the ceramic powder can be degassed on the one hand before the glaze forms a closed glass layer, but on the other hand, under the firing conditions used, forms a smooth, ceramically flawless surface, i.e. not pinprick-like, and develops the decorative effect desired through decoration with decorative paints. This makes it possible to produce, in a single firing process, the so-called single firing, a very high-quality decorated tile. The firing temperature, depending on the intended use of the tile, is between 900

and 1250?C, OOB? in the case of earthenware tiles is generally between 950 and 1100?C (and in the case of stoneware tiles is generally between 1100 and 1250?C. All mixtures of oxides and/or glass frits can be used as glazes, which after firing form a glass layer on the ceramics and satisfy the above conditions.

The glaze powder, uniformly mixed and/or coated with binder, is then introduced, in a thin layer, above or below a layer of ceramic powder in a mold. All natural and synthetic oxide substances and mixtures can be used as ceramic materials, such as clays, feldspars, quartz, calcites, ollastonites, or dolomites. They formally still have a moisture content of between 2 and 10% by weight. After molding, at molding pressures of between 200 and 400 bar, glaze surfaces are obtained that are sufficiently smooth and pressure-resistant to be subsequently decorated using known processes. It may be advantageous to heat the molded pieces to 50-30°C before decorating, or to spray the glazed surface additionally with binder.

Decoration can be achieved with mixtures of ceramic paints and suitable media, for example in direct printing, and then in particular with hydrophilic silkscreen media, brush printing, silicone or steel intaglio printing, thermoplastic printing, and decals. When using quick-drying media in direct printing, several layers of paint can be printed, especially one on top of the other, without intermediate drying.

For example, ceramic paints use mixtures of 5-50% of an inorganic pigment, for example of the ZnO-Cr 0 -Fe 0 -SiO system, and 95-50% of a glass flux, such as 2 3 2 3 2 .

example of the system SiO ?Al 0 -B 0 -ZnO-Na 0-K O-CaO-PbO,

2 23 23 2 2

which are present in a homogeneous and highly fine mixture, and which melt at the firing temperature of the glaze.

After decoration, the firing process takes place. The decorated tiles are subjected to a heat treatment (in single-firing, which, depending on the ceramic material, the glaze, and the structure of the decoration, is carried out in rapid firing within 25 minutes to 3 hours at 900-1250°C, or in normal firing within 3 to 20 hours, also at 900-1250°C.

The following examples will illustrate the process according to the invention in more detail:

6. 850 g of a dry mix of glaze I is wet slurried with 750 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 4, using a dissolver. To prevent foaming, 1 g of a silicone-based defoamer is added. The resulting wet glaze slurry is dried in a spray dryer with a single-substance nozzle at an air inlet temperature of 250°C and an air outlet temperature of 100°C. The polymer coating amounts to 15%.

Under these conditions, a spray granulate is obtained, which has a residual humidity of approximately 0.1% by weight and

an apparent density, according to DIN 53468, of approximately 1,450

g/1. The following grain size distribution is obtained:

15% \ 400jim

65% ' 200 yjm - 400

20% ^ 200jim

Showcase I has the composition

approx. 50% SiO^

approx. 14% Zr02

approx. 10% ZnO

approx. 9% CaO

approx. 6?A1203

approx. 6% 30

2 3

approx. 3% alkaline oxides

approx. 2% MgO.

7. 900 g of the dry mixed showcase I are re?

ducts in a wet mixture with 500 g of an ammonia solution

the (pH 8) to 20?^ polyacrylate (methacrylate) prepared if?

according to example 4, with a dissolver. To prevent the for?

To reduce foaming, add 1 g of an antifoaming agent.

The resulting wet showcase meal is spray-dried

as described in 6.

Polymer coating: 10% by weight.

8. 950 g of the dry mixed glaze are reduced?

you in a wet dough with 500 g of an ammonia solution of the

(pH 8) at 10% /p?lyacrylate (methacrylate) prepared according to Example 4, with a dissolver. To prevent foaming, 1 g of a defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 5% by weight.

9. 930 g of the dry-mixed glaze I is wet-slurried with 500 g of a 4% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 4, with a dissolving agent. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze slurry is spray-dried as described in 6.

Polymer coating: 2.0% by weight.

10. 850 g of a dry mix of glaze II are wet slurred with 750 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 1 using a dissolver. To prevent foaming, 1 g of a silicone-based defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 15% by weight.

Showcase II has the composition

approx. 43% SiO

2

approx. 20% to 0

2 3

approx. 10% CaO

approx. 9% ZrO^

approx. 5% TiO

2

approx. 4% B 0

2 3

approx. 4% alkaline oxides.

11. 900 g of the dry mix of glaze II are wet slurred with 500 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 1 using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 10% by weight.

12. 950 g of the dry mix of glaze II are wet slurried with 500 g of a 10% ammonium solution (pH 8) of the polyacrylate ?v (methacrylate) prepared according to Example 1, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 5% by weight.

13. 930 g of the dry mixed glass II are wet mixed with 500 g of a 4% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 1, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added.

The resulting wet glaze mixture is spray dried

as described in 6.

Polymer coating: 2.0% by weight.

14. 350 g of the dry mixed showcase I are reduced?

you in a wet dough with 750 g of an ammonia solution

(pH 8) at 20% of the prepared polyacrylate (methacrylate)

according to example 2, with the help of a dissolver. For impe?

to say the formation of foam, add 1 g of an antifoaming agent

silicone base. The resulting wet glaze mixture is

spray dried as described in 6.

Polymer coating: 15% by weight.

15. 900 g of the dry mixed showcase I are reduced?

you in a wet dough with 500 g of an ammonia solution

(pH 8) at 20% of the prepared polyacrylate (methacrylate)

according to example 2, with a dissolver. To prevent the for?

To make foam, add 1 g of an anti-foaming agent.

The resulting wet showcase meal is spray-dried

as described in 6.

Polymer coating: 10% by weight.

16. 950 g of the dry mixed showcase I come back?

ducts in a wet mixture with 500 g of an ammonia solution

at 10% (pH 8.) of the prepared polyacrylate (methacrylate)

according to example 2 with a dissolver. To prevent the for?

To form a foam, add 1 g of an antifoaming agent. The resulting wet glaze mixture is spray-dried as described in section 6.

Polymer coating: 5% by weight.

17. 980 g of the dry glaze mix I is wet slurried with 500 g of a 4% ammonium solution (pH 3) of the polyacrylate (methacrylate) prepared according to Example 2 using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze mix is spray-dried as described in Example 6.

Polymer coating: 2.0% by weight.

18. 850 g of the dry mix glaze I is wet slurried with 750 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 3, using a dissolver. To prevent foaming, 1 g of a silicone-based defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 15% by weight.

19. 900 g of the dry-mixed glaze I are wet-slurried with 500 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 3, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 10% by weight.

20. 950 g of the dry glaze mix I is wet slurried with 500 g of a 10% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 3, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze mix is spray-dried as described in .6.

Polymer coating: 5% by weight.

21. 980 g of the dry glaze mix I is wet slurried with 500 g of a 4% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 3, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze mix is spray-dried as described in Example 6.

Polymer coating: 2.0% by weight.

22. 850 g of the dry mix of glaze II are wet-slurried with 750 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 5, using a dissolver. To prevent foaming, 1 g of a silicone-based defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 15% by weight. .

23. 900 g of the dry-mixed glaze II are wet-slurried with 500 g of a 20% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 5 using a dissolver. To prevent foaming, 1 g of a defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 1.0% by weight.

24. 950 g of the dry-mixed glaze II is wet-slurried with 500 g of a 10% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 5, using a dissolver. To prevent foaming, 1 g of a silicone-based defoamer is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 5% by weight.

25. 980 g of the dry mix of glaze II are wet-slurried with 500 g of a 4% ammonium solution (pH 8) of the polyacrylate (methacrylate) prepared according to Example 5, using a dissolver. To prevent foaming, 1 g of an antifoaming agent is added. The resulting wet glaze slurry is spray-dried as described in Example 6.

Polymer coating: 2.0% by weight.

The polymer-modified glaze powder thus prepared is molded together with a material powder consisting of 70% clay and 30% feldspar. To this end, the glaze is applied in a thin layer over the material powder in the mold (15 x 15 cm) of a hydraulic press, compacted at -300 bar. Depending on the glass transition point and the amount of polymer applied, the material can then be molded immediately, or a tempering process must be performed before the molding process.

Subsequently, the printed, unfired tiles are examined for their edge and surface stability, as well as for the crumbling behavior of the glazed surface, using a finger test. Grades from 1 to 6 are assigned (1 = very good, 6 = completely inadequate).

The printability of the unfired glazed surface is tested with various printing inks. After every 500 printing processes, the screen is tested for contamination by loose frit particles. The tiles are then fired.

The results of these tests are recorded in Tables I and II (dry-printed tiles without heat treatment) and III and IV respectively (dry-printed tiles with 1 hour tempering at 603C).

From the tables you can see that the Icos tiles?

cate( present properties from very good to satisfactory?

you depending on the glass transition temperature and the

quantity of polymers used.

Table 1: Dry-printed tiles without tempering

(Molding temperature 20?C)

Fried of

Showcase Point of Correlation according to Coating transition Stability Stability of the example of glassy polymer_ of the edges the surfaces chalking

none 6 6 6 6 15% - 27?C 1 1 1 7 10% - 27?C 2 1 1 8 5% - 27?C 2-3 1 1-2 9 2.0% - 27?C 4 2-3 4 10 15% 0?C 2 1 1 11 10% 0?C 2-3 1 1 12 5% 0?C 3 2 2-3 13 2.0% 0?C 5 4 5

15% 32*C 2 1 1

10 ? 32?C 3 1 1

16 5 % 32?C 4 2 3 17 2.0 % 32?C 5 3-4 5 18 15 % ao?c 5 2 3 19 io ? ao?c 5 3 4 20 5 % ao?c 5-6 4 5 ZI 2.0 % ao?c 6 5 6 22 15 % ? - 50?C 1 1 23 10 % - 50?C 1 1 1 24 5 % - 50?C 2-3 1 1 25 2.0 % - 50?C 4 2 2-3 Table II: Dry-printed tiles without tempering

(Molding temperature 20?C)

Fried of Insudiciainento of the

screen display after 500

according to procedures of

11example Printability? print_ _ Cooking

without po not indicated clogged after the pri very good limeri mo printing process,

6 very good none very good 7 very good none very good 8 very good none very good 9 sufficient slight very good 10 very good none very good 11 very good none very good 12 good completely slight very good 13 insufficient evident very good 14 very good none very good 15 very good none very good 16 sufficient slight very good 17 insufficient evident very good 13 good completely slight very good 19 insufficient evident very good 20 insufficient evident very good 21 poor strong very good 22 very good none very good 23 very good none very good 24 very good none very good 25 good slight very good Table III: Dry-printed tiles (after printing, tempering for 1 hour at 60°C)

Fried of

Fake showcase Stability? Dry behavior Coating transition Stability of the of the example of glassy polymer_ of the edges surfaces chalking none ? \ & i ^ 6 * 1- l" '

6 15 * j-27 ?C j 1 1 1 1 ? 7 10. % -27 ?C ! 1 1 1 ? the

8 5 * 1-27 ?C 2 1 1 9 | 2.0 X -27 ?C 3-4 i 2 3 !

10 15 * 0 ?c 1 1 1 11 10 % 0 ?c 1 j 1 -1

12 5 % 0 ?c 2 ! 1 1 13 ' 2.0 * 0 ?C ! 3-4 1 2 3 14 15 * !*32 ?C i l i l 1

1 ?

15 j 10 % ?+32 ?C | 2 1-2 1 16 5 % 32 ?C j 3-4 j 2 2-3 7 2.0 X 32 ?C | 4-5 1 3-4 3-4 .

1 1

1

8 15 X |+80 ?C j 3 j 1 1 9 10 X 80 ?C 2-3

1 3 1 2

0 5 X 80 ?C 4 3-4 4 1 2.0

15 X 1 -50 ?C 1 1 1 10 X -50 ?C ; 1 | 1 1 5 X -50 ?C ; 1-2 ! 1 1 T? 2.0 X -50 ?C 3 1! 1-2 2 Table IV: Dry-stamped tiles {after stamping?

(tempering for 1 hour at 60?C)

Fry of Dirt

screen showcase after

according to 500 proceedings

the example Printability of printing Cooking

without not mentioned clogged after the pri^ very good polymer sqm printing process

6 very good none very good 7 very good none very good 3 very good none very good 9 sufficient slight very good 10 very good none very good 11 very good none very good 12 very good none very good 13 sufficient slight very good 14 very good none very good 15 very good none very good 16 good quite slight very good 17 sufficient slight very good 18 very good none very good 19 good quite slight very good 20 sufficient slight very good 21 insufficient evident very good 22 very good none very good 23 very good none very good 24 very good none very good 25 good slight very good

Claims (6)

1. Process for the manufacture of decorated glazed ceramic products using the single-firing technique, by moulding together two layers of a ceramic material and a glaze powder, followed by decoration of the glaze layer and firing at 900-1250°C, characterised in that the glaze powder, prior to moulding, is uniformly mixed and/or coated with a binder present in the aqueous phase, consisting of organic polymeric compounds with glass transition temperatures of -50 to 80°C. 2. Process for the manufacture of decorated glazed ceramic products according to claim 1, characterised in that organic polymeric compounds having a glass transition temperature in the range from -50°C to 40°C are used as binders. 3. Process for the manufacture of decorated glazed ceramic products according to claims 1 and 2, characterised in that polymers based on acrylic acid and methacrylic acid, or their esters, respectively, are used as binders. 4. Process for the manufacture of glazed, decorated ceramic products according to claims 1 to 3, characterised in that the binder is added to the glaze powder in quantities of 1 to 15% by weight of the glaze powder. 5. Process for the manufacture of decorated glazed ceramic products, according to claims 1 to 4, characterised in that the glaze powder mixed with binder is spray-dried. 6. Process for the manufacture of decorated glazed ceramic products according to claims 1 to 5, characterised in that after moulding, a further binder is applied to the glaze surface. 1. A process for manufacturing decorated glazed ceramic products using the single-firing technique by molding together two layers of a ceramic material and a glaze powder, followed by decorating the glaze layer and firing at 900-1250°C, characterized in that the glaze powder, before molding, is uniformly mixed and/or coated with a binder present in the aqueous phase, consisting of organic polymeric compounds with glass transition temperatures of -50°C to 30°C. 2. A process for manufacturing decorated glazed ceramic products according to claim 1, characterized in that organic polymeric compounds having a glass transition temperature in the range of -50°C to 40°C are used as the binder. 3. Process for the manufacture of decorated glazed ceramic products according to claims 1 and 2, characterised in that polymers based on acrylic acid and methacrylic acid, or their esters, respectively, are used as binders. 4. Process for the manufacture of glazed, decorated ceramic products according to claims 1 to 3, characterised in that the binder is added to the glaze powder in quantities from 1 to 15% by weight of the glaze powder. 5. Process for the manufacture of glazed, decorated ceramic products, according to claims 1 to 4, characterised in that the glaze powder mixed with binder is spray-dried. 6. Process for the manufacture of decorated glazed ceramic products according to claims 1 to 5, characterised in that after moulding, a further binder is applied to the glaze surface.