CERAMIC LINING SHEET FOR EXTERNAL USE

Abstract

Coating plate in ceramic material for outdoor application, obtaining method and use thereof. The ceramic coating plate for outdoor application comprises a vitreous layer wherein the vitreous layer comprises 3-30% (m/m) of an infrared reflective pigment, wherein the infrared reflective pigment comprises titanium dioxideTiO.sub.2.

Said plate provides the user with thermal comfort in contact between the plantar surface of the feet and the ceramic material and may also be used in the coating of faades, or upper coverings.

TiO.sub.2 concentration may be 5-25% (m/m), 8-20% (m/m), or 9-11% (m/m). TiO.sub.2 particles have a size between 0.1-2 m, more preferably 0.25-2 m. The infrared reflective pigment may further comprise metal oxides Al.sub.2O.sub.3, SiO.sub.2, MnO, SbO, Fe.sub.2O.sub.3, or mixtures thereof.

Said plate may be a tile, a ceramic, a mosaic, a paving block or a slab, among others.

Claims

1. Ceramic coating plate for outdoor application comprising a vitreous layer wherein the vitreous layer comprises 3-30% (m/m) of an infrared reflective pigment, wherein the infrared reflective pigment comprises titanium dioxideTiO.sub.2.

2. Plate according to the previous claim wherein TiO.sub.2 concentration is between 5-25% (m/m).

3. Plate according to any of the previous claims wherein TiO.sub.2 concentration is between 8-20% (m/m).

4. Plate according to any of the previous claims wherein TiO.sub.2 concentration is between 9-11% (m/m).

5. Plate according to any of the previous claims comprising TiO.sub.2 particles with a size ranging between 0.1-2 m.

6. Plate according to the previous claim comprising TiO.sub.2 particles with a size ranging between 0.25-2 m.

7. Plate according to any of the previous claims wherein the infrared reflective pigment further comprises metal oxides Al.sub.2O.sub.3, SiO.sub.2, MnO, SbO, Fe.sub.2O.sub.3, or mixtures thereof.

8. Plate according to the previous claim wherein the reflective pigment is a combination of TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2 or TiO.sub.2, MnO and SbO.

9. Plate according to any of the previous claims comprising infrared reflective pigment particles with a size ranging between 0.1-2 m.

10. Plate according to the previous claim comprising infrared reflective pigment particles with a size ranging between 0.25-1 m.

11. Plate according to any of the previous claims further comprising at least 1% (m/m) of a coloured inorganic pigment.

12. Plate according to the previous claim wherein the coloured inorganic pigment concentration is between 1-10% (m/m).

13. Plate according to the previous claim wherein the coloured inorganic pigment concentration is between 2-6% (m/m).

14. Plate according to any claim 11-13 wherein one or more coloured inorganic pigments are selected from the following list of pigments: iron, chromium, nickel, manganese, zinc, or mixtures thereof.

15. Plate according to any of the previous claims wherein TiO.sub.2 is in rutile form.

16. Plate according to any of the previous claims wherein the ceramic material is a stoneware.

17. Plate according to any of the previous claims wherein the plate is a tile, a ceramic, a mosaic, a paving block or a slab.

Description

DETAILED DESCRIPTION

[0033] In one embodiment, the ceramic coating plate comprising TiO.sub.2 in the vitreous layer presents the desired effect by changing the ceramic material and not by applying additional layers, including layers for reflection effect and layers to promote colour. With the development performed, it is still possible to obtain the desired effect, while maintaining the conventional process of ceramic coating production as well as the technical properties of the material, which represents an added value for ceramic industry. Another aspect of valorisation of the development performed is the aesthetical versatility of the product, due to the possibility of having a variety of colours and styles, namely for imitation of wood pavements. For this specific case, the development performed allows obtaining a ceramic coating plate comprising TiO.sub.2 in the vitreous layer with wooden appearance and improved performance in terms of infrared radiation reflection. In this way, the development performed allows combining the added values of two types of material into one: the technical properties of ceramics, such as weather and abrasion strength, the aspect and thermal comfort of wood and also the reduction of colour degradation.

[0034] In one embodiment, TiO.sub.2 was added as infrared reflective pigment in a conventional stoneware. The choice of the stoneware was based on its appearance close to wood and its applicability in outdoor environments, where the need for reducing temperatures reached on hot days is crucial. Since being a more ambitious challenge, a dark colour stoneware was selected, however, the scientific-technological development hereby described may be adapted to several other products, with other styles and colours.

[0035] In one embodiment, the addition of the infrared reflective pigment in the stoneware's superficial layer, i.e., in the vitreous layer, the ceramic slab was produced from conventional raw materials, namely clays, feldspars, silicas, kaolins and additives, among others.

[0036] In a preferred embodiment for better results, the IR reflective pigment used consists of a pigment based on titanium dioxide (TiO.sub.2) in its rutile form, with a particle size between 0.2-2 m, with a d90 of 1 m. The particle size of the TiO.sub.2 pigment allows obtaining a high IR reflectivity with a minimized reflectance in the visible, relatively to common TiO.sub.2. In this way, this pigment has a low pigmentation power, being particularly adequate for situations when obtaining various colours is desired.

[0037] In a preferred embodiment for better results, colour pigments have also been used, already commonly used in ceramic coating industry for aesthetical effects, namely pigments of inorganic base (Fe, Cr, Zn and Ni) with brown and black tonalities. It should be mentioned that the selection of these pigments took the desired final colour with dark brown tonality into consideration, as well as the high chromatic yield of the pigments and an excellent behaviour in all types of glass. For obtaining other tonalities, other colour pigments should be used, underlining that the development described is not limited to the colour pigments herein presented.

[0038] Preparation of samples was based on the conventional procedure for technical stoneware production, which encompasses three main stages: pressing, glazing/decoration and firing.

[0039] In the pressing stage, the compaction and conformation of the atomized powders may be performed for obtaining the ceramic mosaic. In the present disclosure this stage was performed in the conditions defined for conventional stoneware.

[0040] In one embodiment in the glazing/decoration stage, different types of applications may be carried out in order to obtain completely different drawings, effects and textures. In the ceramic coating plate, a process of digital printing has been carried out for obtaining the wood effect, followed by a glazing process, which provides the ceramic coating with a superficial layer. In the solution described a composition of the glass (vitreous) solution has been developed, keeping the plate production process unchanged. The infrared reflective pigments previously mentioned, such as TiO.sub.2, were incorporated in an aqueous glass solution previously prepared based on the materials and methods defined for the original technical stoneware. To 100% (m/m) of the glass solution, 10% (m/m) TiO.sub.2 was added with a particle size distribution between 0.21-1 micrometre, and a d90 of 0.91 micrometre, 5% (m/m) Brown and 1% (m/m) Black. The reflective pigmentTiO.sub.2 may be incorporated in the glass solution in quantities between 3 and 20% (m/m), preferably between 5 and 15% (m/m), whereas, below the minimum threshold, the reflective effect becomes of minor significance and, above the maximum threshold, the desired colour, namely dark colours, may be compromised. The quantities of colour pigments should be adjusted depending on the quantity of reflective pigment incorporated and/or the intended tonality of the ceramic plate.

[0041] In one embodiment, the mixture obtained has been homogenized within a mechanical paddle agitator and, subsequently, applied over the ceramic mosaic. This stage was performed in laboratorial environment, through spraying technique, with a coupled compressed air system, at a pressure of 2 bar. The grammage of applied glaze was about 130 g/m.sup.2, according to the technical data of this type of stoneware. Other wet glazing techniques may be considered, particularly in industrial environments, from continuous application techniques (curtain, bell) to spraying techniques (gun, disc, cabin).

[0042] In one embodiment, the ceramic coating production process is concluded in the firing stage, which promotes the transformations needed for obtaining products with the desired technological and aesthetical characteristics. This sintering process is specific and adjusted to each product, so as to promote and guarantee the final characteristics. The firing of the ceramic mosaic comprising TiO.sub.2 was performed in high temperature furnaces, according to a usual heating program for the original technical stoneware. The heating program used was the following: heating up to 1200 C.; four dwell segments at 1200 C.; fast cooling to room temperature; total cycle time 60 minutes.

[0043] In one embodiment, after the stoneware comprising TiO.sub.2 in the vitreous layer had been obtained, performance assessment assays were performed in terms of thermal behaviour upon exposure to solar radiation and infrared radiation. For comparison purposes, a common technical stoneware and two samples of wood for deck application were also assessed. The stoneware developed and described in the present disclosure presents an identical tonality to that of the product developed in the original stoneware. Regarding the wood samples, both of brown tonality, one of the samples having a light tone (designated Wood Deck 1) and the other having a darker tone (designated Wood Deck 2).

[0044] In the solar exposure assay, samples were exposed to this radiation (in an outdoor location) for 6 hours and their surface temperature was registered during the assay. The assessment was done at maximum temperature reached in the assay for each sample.

[0045] In the infrared exposure assay, samples were placed under infrared lamps (Philips, 1100 W power), at a distance of 30 cm, for 30 minutes. After this period, the temperature reached on the surface of the samples was registered. Room temperature was 19 C.

[0046] In both assays, surface temperature determination was performed using an infrared thermometer (Infrared Thermometer TES 1327K).

[0047] Throughout the description and claims the word comprises and variations of the word, do not intend to exclude other technical characteristics, additives, components, or steps. Additional objects, advantages and characteristics of the invention will become apparent to one skilled in the art upon examination of the description or may be learned through practice of the invention. The following examples are provided by way of illustration, and do not intend to be restrictive of the present invention. In addition, the present invention encompasses all possible combinations of particular or preferred embodiments herein described.

[0048] Followingly, the results obtained in the performance assessment assays are presented in terms of thermal behaviour under exposure to solar radiation and infrared radiation.

[0049] Table 1 presents the temperature values obtained in the assays performed for the technical stoneware with 10% TiO.sub.2-based pigment, for the original technical stoneware and for wood substrates.

Example 1Stoneware without Reflector

[0050] The preparation of the stoneware without reflector was based on the conventional procedure for the production of technical stoneware, which encompasses three main stages: pressing, glazing/decoration and firing.

[0051] In the pressing stage, compaction and conformation of atomized powders for obtaining the ceramic mosaic was performed, at a pressure of about 400 kgf/cm.sup.2.

[0052] In the glazing/decoration stage, a digital printing process was performed for obtaining the wood effect, followed by a glazing process, which provides the ceramic coating with a superficial layer.

[0053] The firing of the stoneware without reflector was performed in high temperature furnaces, using the following heating program: heating up to 1200 C.; four dwell segments at 1200 C.; fast cooling to room temperature; total cycle time 60 minutes.

Example 2Stoneware with IR Reflective Pigment Comprising TiO.SUB.2., Al.SUB.2.O.SUB.3 .and SiO.SUB.2

[0054] The preparation of the stoneware with IR reflective pigment comprising TiO.sup.2, Al.sub.2O.sub.3 and SiO.sub.2 was based on the procedure described in Example 1. The main change was done at the glass solution composition level, with no changes undertaken to the process. In this example, this stage is thus described in more detail.

[0055] The reflective pigment comprising TiO.sub.2, Al.sub.2O.sub.3 and SiO.sub.2 was incorporated in a conventional glass aqueous solution of the stoneware described in Example 1. To 100% (m/m) of the glass solution, 10% (m/m) TiO.sub.2 was added with a particle size distribution between 0.21-1 micrometre, and a d90 of 0.91 micrometre, 5% (m/m) of coloured pigment of brown tonality and 1% (m/m) of coloured pigment of black tonality. The mixture obtained was homogenized within a mechanical paddle agitator and, subsequently, applied over the ceramic mosaic. This stage was performed in laboratorial environment, through spraying technique, with a coupled compressed air system, at a pressure of 2 bar. The grammage of applied glaze was about 130 g/m.sup.2.

Example 3Stoneware with IR Reflective Pigment Comprising TiO.SUB.2., MnO and SbO

[0056] The preparation of the stoneware with IR reflective pigment comprising TiO.sub.2, MnO and SbO was based on the procedures described in Examples 2 and 3. The main change was done at the glass solution composition level, wherein to 100% (m/m) of the glass solution, 10% (m/m) of the pigment comprising TiO.sub.2, MnO and SbO was added.

Example 4Performance Assessment of the Developed Stoneware

[0057] The performance assessment was undertaken in terms of thermal behaviour under exposure to solar radiation and infrared radiation. For comparison purposes, two samples of wood for deck application were also assessed. These samples present brown tonalities, one of the samples having a light tone (designated Wood Deck 1) and the other having a darker tone (designated Wood Deck 2).

TABLE-US-00001 TABLE 1 Temperatures obtained for materials assessed in the exposure to solar radiation and infrared radiation assays Solar Infrared Sample T max ( C.) T after 30 min ( C.) Stoneware without reflective 55.2 48.6 pigment Wood Deck 1 49.2 41.1 Wood Deck 2 51.4 41.1 Stoneware with 5% (m/m) IR 50.2 35.6 reflective pigment with TiO.sub.2, Al.sub.2O.sub.3 and SiO.sub.2 Stoneware with 5% (m/m) IR 35.7 reflective pigment with TiO.sub.2, MnO and SbO

[0058] In the solar exposure assay, samples were exposed to such radiation (in an outdoor location) for 6 hours and their surface temperature was registered during the assay. The assessment was done at the maximum temperature reached in the assay for each sample. In the infrared exposure assay, the samples were placed under infrared lamps (Philips, 1100 W power), at a distance of 30 cm, for 30 minutes. After this period, the temperature reached on the surface of the samples was registered. Room temperature was at 19 C. In both assays, the surface temperature determination was performed using an infrared thermometer (Infrared Thermometer TES 1327K). Table 1 shows the performance assessment results.

[0059] In Table 1, the performance assessment was done in terms of thermal behaviour under exposure to solar radiation and infrared radiation. For comparison purposes, two samples of wood for deck application were also assessed. These samples have brown tonalities, one of the samples having a light tone (designated Wood Deck 1) and the other having a darker tone (designated Wood Deck 2).

[0060] In the solar exposure assay, samples were exposed to such radiation (in an outdoor location) for 6 hours and their surface temperature was registered during the assay. The assessment was done at maximum temperature reached in the assay for each sample.

[0061] From the analysis, the first observation registered has to do with the fact that stoneware for outdoor application comprising TiO.sub.2 in the vitreous layer presents a superior performance over conventional stoneware (stoneware without reflective pigment). This difference has higher significance in the infrared radiation exposure assay, where a temperature reduction of about 13 C. was achieved. In this assay, it has also been noticed that stoneware developed and described in examples 2 and 3 is beyond the reference materials, namely Wood Deck 1 and Wood Deck 2. In a preferred embodiment, obtaining a ceramic coating with visual appearance of wood and with identical or superior performance to wood coatings for deck application was intended. The improvement of the stoneware described in example 2 over wood materials becomes less apparent in the solar exposure assay. Upon assessing the values obtained in the solar exposure assay, it has been verified that the ceramic coating plate for outdoor application comprising TiO.sub.2 in the vitreous layer presents a temperature lower than that of sample Wood Deck 2, however, higher than that of Wood Deck 1. The difference observed in wood samples may be due to their tonalities, in that sample Wood Deck 1 presents a lighter colour relatively to Wood Deck 2 and, according to the exposed in the state of the art, lighter colours tend to have higher reflectivity. Upon a joint analysis of the two assays, it has been verified that the values of temperature reached are globally higher in the solar exposure assay. This observation may be due to the assay conditions being different, namely at room temperature level: in the solar radiation exposure assay, the temperature had a value of about 30 C., while, in the IR radiation exposure assay, room temperature was at 19 C. The registered difference in room temperature may be influencing the sample heating, since this process results from three phenomena of heat transfer: radiation, convection and conduction. In the infrared radiation exposure assay, heating is essentially by radiation, since the surrounding air and materials in contact with the samples are at a relatively low temperature (about 19 C.). In the case of solar radiation, besides the heating resulting from the radiation emitted by the sun, the high temperature of the surrounding air may be causing heating by convection.

[0062] Additionally, the materials in contact with the samples, also undergo heating, contributing to the temperature increase of the samples by conduction. Therefore, in the solar exposure assay, the main contribution for sample heating won't be only dependent on the phenomenon of heat transfer by radiation. These conjectures are particularly interesting for the analysis and comparison of the values obtained for the different samples: wood samples, although having less reflective power, as observed in the IR exposure assay, have a similar performance to the developed stoneware in the solar exposure assay, maybe due to presenting lower values of thermal conductivity than ceramics. In this way, the heating occurred in these samples by convection and conduction phenomena is less significant, leading to a lower temperature increase on the surface thereof.

[0063] In short, as a result of the analysis of the table values and assay conditions, it has been observed that the incorporation of the reflective pigments in the ceramic product allows improving their performance in terms of IR radiation reflection. Under solar exposure, this effect is less pronounced, however an improvement over the original technical stoneware is still observed.

[0064] In view of the results obtained, it is possible to conclude that the incorporation of TiO.sub.2 in the ceramic vitreous layer significantly changes the coating behaviour. The ceramic coating plate comprising TiO.sub.2 in the vitreous layer has a high performance in terms of infrared reflection, translating into a decrease of the maximum temperature reached under solar exposure. This feature allows the application of ceramic coatings in outdoor pavements, thus providing the user with thermal comfort in the contact between the plantar surface of the feet and the ceramic material. Another advantage of ceramic coating plate with this feature is the possibility of application in faades, due to the fact that the temperature reached by ceramic materials is within the range considered by producers of glues for faades, thus guaranteeing the performance thereof.

[0065] Embodiments described above are combinable with each other.

[0066] The present invention is of course in no way restricted to the embodiments herein described and a person of ordinary skill in the art will be able to provide many modification possibilities thereto and substitutions of technical features for equivalents, according to requirements in each situation, as defined in the claims.

[0067] The following claims further define preferred embodiments.