EP2782885A1

EP2782885A1 - Method for treating a surface of a mineral substrate, and shaping object produced according to the method

Info

Publication number: EP2782885A1
Application number: EP12775007.3A
Authority: EP
Inventors: Jan Interwies
Original assignee: N TEC GmbH; n-tec GmbH
Current assignee: Cosentino Research and Development SL
Priority date: 2011-11-24
Filing date: 2012-10-15
Publication date: 2014-10-01
Also published as: WO2013075887A1; DE102011087060A1; DE102011087060B4

Abstract

The invention relates primarily to a method for treating a surface of a mineral substrate and to objects produced according to the method, in particular objects having a surface which is designed to be slip-proof, dirt-resistant, abrasion-optimized, scratch-resistant, heat-reflecting, self-cleaning and/or prevents fouling or is in general antimicrobial.

Description

Process for treating a surface of a mineral substrate and after

Process produced molded article

The present invention relates to a method for treating a surface of a

mineral substrate and a molded article produced by the process, in particular a process for treating the surface of substrates such as tiles,

Roof tiles, glass, in particular glass panes, concrete, ceramics, sanitary ware, or stoneware.

Background of the invention

For some time, techniques for changing the surface properties of various materials and substrates from a variety of fields have been of particular interest. By means of such methods, the surfaces should e.g. Dirt-repellent, photocatalytic, slip-resistant, heat-reflecting, anti-fouling or generally antimicrobial, scratch-resistant, highly abrasion-resistant or combinations of these properties are awarded.

It is well known that many mineral surfaces are attacked with hydrofluoric acid and this is used for surface modification. In these methods, however, it comes exclusively to the removal of material. Since no other reactant reacts with the surface, such methods may be used to improve the skid resistance of

However, surfaces have the disadvantage that they cloud the surface and that must be worked with hazardous hydrofluoric acid.

Also, a partial removal of the surface by laser treatment to increase the

Skid resistance by structuring the surface is performed. However, it is disadvantageous that this is a complex method of finishing. In addition, this procedure causes an increase in soil sensitivity, a loss of material, and effects such as visible structuring, matting or turbidity.

Another possibility u. a. in unglazed ceramic objects the

Changing surface properties may be the change in the composition of the molding compound due to addition of a functionalizing material. The disadvantage here, however, is that the functionalizing material is distributed throughout the article. That it requires a high use of materials, wherein a part of the functionalizing material is due to the process in areas distributed in the interior of the object, which for the

Surface properties does not matter. In addition, the functionalizing substance must withstand the firing temperature when firing the article without undesirably changing. In glazed or engobe coated ceramic objects, the glaze or engobe for changing the surface properties, for example with a

functionalizing substance. Here, too, a higher material usage is required because functionalizing material is distributed throughout the glaze or engobe. In addition, the firing temperature of the glaze or engobe must also be withstood by the functionalizing substance.

Finally, an additional functional coating can be applied to the surface. As a result, however, a surface layer is formed, which can be damaged and infiltrated. The optics of the item i. d. Usually influenced, z. B. changes the degree of gloss or color impression. There may also be increased reflection of light at certain angles through the additional interface.

In view of the disadvantages of the prior art processes, it is an object of the present invention to provide a process for treating a surface of a mineral substrate and an article produced by the process, wherein the disadvantages known from the prior art are at least partially overcome become.

Description of the invention

The object of the present invention is generally achieved by a method according to the appended claim 1 and a method according to claim 1 and a molded article according to claim 17. Advantageous embodiments of the invention are the subject of the corresponding dependent claims.

The invention avoids the disadvantages of the prior art in that it provides a treating solution or suspension for use in a method of treating a surface of a mineral substrate, which subsequently adds the surface of the article, with low material usage and firing, as compared to ceramic firing, functionalized at a reduced temperature and thereby generates a modified layer in the article itself, which is firmly connected to the article. In this case, the change in the substrate proceeds spatially from the outside to the inside, with no recognizable phase boundary, forming a decreasing gradient of the change.

In an alternative embodiment of the present invention, the method for treating a surface of a mineral substrate is carried out such that the treatment solution or suspension according to the invention before the ceramic firing of the mineral substrate, So on the green compact, applied and then the required to obtain the final product firing, optionally after drying the thus treated green compact, is performed. Another temperature treatment or heating can then

be omitted, thereby advantageously saving an energy-intensive process step compared to other end products in the production.

The present invention will be explained in more detail below with reference to the accompanying figures and to the embodiments. Show it:

1 shows a schematic section through an article produced by the inventive method with modified surface and

Figure 2 is a schematic section through one of the prior art

coated object.

The treatment solution or suspension according to the invention contains colloidal and / or dissolved substances and it has been found that after subsequent heating or

Temperature treatment leads to a particularly strong binding of the applied material in the surface or in the upper layer of the substrate. This is demonstrated by the extremely high resistance to abrasion in the PEI test, a test procedure developed by the Porcelain Enamel Institute in the USA in 1938, which today standardizes grinding and sandblasting tests against the resistance to abrasion of floor tiles, and an extremely high level of abrasion resistance

Resistance to acids and alkalis. In both properties, results are achieved which go far beyond what one would expect from an applied layer consisting of the pure, dissolved and / or colloidal substances. The effect occurs particularly when the composition of the surface of the article in combination with the composition of the treatment solution or suspension in about the composition of a particularly durable glass, a particularly durable ceramic or even a particularly resistant composite material, both ceramic and glassy Shares. This is described in more detail by adding hereinafter in connection with further advantageous embodiments of the method according to the invention

Network formers and / or stabilizers and / or network converters reached. In a

According to a preferred embodiment of the present invention, the treatment solution or suspension therefore contains one or more stabilizers and / or network converters. The connection to the substrate takes place surprisingly at a temperature which is sometimes several hundred degrees Celsius below the temperature at which a correspondingly composed bulk glass or a corresponding ceramic would melt. To avoid misunderstandings is It should be noted that this effect is described with respect to a corresponding glass or ceramic, but is generally within the scope of the present invention. For example, even at a temperature which is below the firing temperature for the glaze of a tile or under the firing temperature of a ceramic or stoneware and also below the firing temperature for ceramic coatings or their Einbrenndauer greatly shortened.

With respect to the desired composition of the modified surface, the

Composition of the treatment solution or suspension complementary to

Composition of the surface or upper layer of the substrate selected in the initial state. Also, the composition of the suspension is chosen so that it in the

subsequent temperature treatment to a reaction between the components of the treatment solution or suspension and those already contained in the surface

Network creators, stabilizers or network converters comes.

The tuning of the content of the ingredients in the treatment solution or suspension is explained below and is based on various aspects.

The network or lattice of the surface layer is mainly determined by Si0 ₂ . The network-converting alkaline earth metal oxides, zinc oxide and boron oxide cause a decrease in the viscosity of the glass or the softening point and thus ensure better flow and smoother surfaces. However, if they are too high, these substances reduce the chemical stability of the resulting surface. The boron oxide content in the surface should therefore not exceed 40% according to the invention, preferably in the range of 15-30%. Permanently chemically resistant glasses are achieved with a silicon dioxide content of more than 60%. The chemical and mechanical resistance of the surface can be further improved by the addition of Al ₂ 0 ₃ , Ti0 ₂ and Zr0 ₂ . In order to obtain a corresponding composition in the surface, the coating material, ie the coating solution or suspension, is adjusted according to the invention with regard to the surface composition or the composition of the upper layer of the substrate. The term "layer" does not necessarily designate a classical layer which can be recognized, for example, by a phase boundary, but in particular also an upper, or generally outer, region of the substrate with a certain spatial extent directed into the interior of the substrate.

In this context, it should be emphasized that the modification of the surface or of the upper layer of the substrate according to the invention is achieved by the fine distribution of the constituents contained in a treatment solution or suspension. In contrast to a classic glaze, the constituents of the suspension according to the invention are significantly more finely divided, preferably with an average diameter D50 <100 nm, in particular or particularly preferably with an average particle diameter D50 <50 nm. This enables a reaction or reaction of these constituents with the uppermost layer of the substrate, which results in a reshaping of the structure of the uppermost layer. By this transformation of the structure, the surface properties change and can be determined by the appropriate choice of

Influence components of the treatment solution or suspension as desired.

According to a generally preferred embodiment of the present invention, the modifying constituents of the treating solution or suspension are present therein in a proportion in the range of about 0.05 to 10% by weight. At a higher level, deposition occurs primarily on the surface of the substrate, and infiltration or diffusion into the surface area of the substrate is not sufficiently accomplished. That is, the pores are closed too quickly, the diffusion prevented. It is preferred if the concentration of the modifying constituents is 0, 1 to 7 wt .-%, since in this area can be worked particularly economically in terms of material usage, process control and process results.

It was confirmed experimentally that silicate surfaces with

Coating suspensions, ie, can be treated with coating solutions or suspensions, which have only a low or no Si0 ₂ content and it nevertheless comes to chemical resistant surfaces. This can be explained by the fact that due to the small depth, in which the surface modification takes place, in the

Substrate surface, that is, the silicon contained in the upper substrate layer or in the upper spatial region of the substrate is sufficient as a silicon source and possibly a supply of

Network converters to modify in principle sufficient.

In the case of non-silicate surfaces, for example Al ₂ O ₃ , the coating solution or suspension must contain SiO ₂ and possibly network converters, so that even at low temperatures it melts with the surface.

The following Table 1 shows by way of example the typical composition of a treatment solution or suspension according to the invention for use on glass and glazed surfaces. Table 1 :

On unglazed surfaces or silicon-free, technical ceramics, the

Treatment solution or suspension to be adapted, inter alia, to the lower silicon content.

A corresponding composition of such a treatment solution or suspension is given by way of example in Table 2.

Table 2:

The values given in the tables refer to the solids used for the preparation or the corresponding solids content and are to be regarded as illustrative examples and not as absolute values. It will be explained using this information that, for example, for glass surfaces in the present invention less Si0 ₂ is contained in the coating composition, since a reaction or reaction with the water present in the substrate Si0 _2, the Si0 ₂ "brought" in the reaction so from the glass becomes.

For ceramics less Si0 _{2 is present} in the substrate, but more Al ₂ 0 ₃ , which in turn means that more Si0 ₂ or B ₂ 0 _3, for example, in the finishing material, ie in the coating composition is needed.

The coordination of the reactive substances takes place with regard to the desired properties of the modified surface: An increase in the proportion of aluminum, zirconium and boron in the surface layer leads to an increase in the surface hardness of silicate substrates. A high Borkonzentration favors the dissolving or melting of the substrate, which leads to relatively smooth, scratch-resistant and highly abrasion-resistant surfaces.

By suitable choice of the reactive substances, it is also possible to adjust the pH of the surface which arises on contact with moisture. Acid oxides permanently lower the pH of the surface, making the surface antimicrobial. Basic oxides can raise the pH of the surface, which suppresses the growth of mold, moss and algae.

A suitable suspension for the anti-fouling or general antimicrobial finishing of regular float glass includes a combination of boric acid in conjunction with

Alkali metal oxides, copper and / or a zinc or tin source.

It is therefore generally preferred that the treatment solution or suspension further comprises one or more network formers selected from the group consisting of Si0 ₂ , Ge0 ₂ , P ₂ 0 ₃ and B ₂ 0 ₃ , and / or one or more stabilizers selected from A group consisting of Al ₂ O ₃ , SnO, TiO ₂ , ZrO ₂ , FeO, Fe ₂ O ₃ and MnO, and / or one or more network converters selected from the group consisting of BaO, CaO, K ₂ O, Li ₂ 0 and, Na ₂ 0, is added or become.

The addition of Si0 ₂ , Ge0 ₂ and B ₂ 0 ₃ leads to the increased formation of a melt phase. With eg P ₂ 0 ₅ , the surface can be adjusted to acidic, which has an antibacterial effect. With BaO, CaO, K ₂ 0, Li ₂ 0 and, Na ₂ 0, the pH of the surface can be raised, which prevents the growth of moss and algae. In addition to the reactive substances mentioned above, additional functionalizing materials may additionally be present in the suspension. For antifouling equipment, copper, silver, tin and / or zinc may be used in metallic form or in the form of their salts. Also, fluorine, in the form of a corresponding salt mediates antimicrobial

Properties. When used in conjunction with the reactive substances, the metals or the fluorine are firmly incorporated into the glassy or semi-crystalline structure, thus ensuring lasting protection against growth by microorganisms. By penetrating and distributing the antimicrobial substances in the structure of the modified surface layer, a high depot effect is achieved. In general, in this way, the substrate will impart certain antiseptic properties which are not diminished by rapid washing out of the antimicrobial substances, but have a lasting effect. Permanently antimicrobial surfaces in this way prevent the spread of bacteria as they inhibit their growth and are not overgrown by moss and mold.

The introduction of titanium leads with suitable temperature control in the aftertreatment to the formation of anatase crystals and thus to photocatalytic activity and hydrophilicity of the surface.

When titanium dioxide in the anatase modification is incorporated into the surface layer, a surface is formed which exhibits photocatalytic activity. In the pure anatase, the wavelength of the light causing the photocatalytic effect is in the UV range, corresponding to the band gap of 3.2at Anatase. By appropriate doping, however, the band gap of anatase can be shifted into the visible range. As suitable dopants, the elements boron, aluminum, calcium, magnesium, barium, silicon, carbon, sulfur, nitrogen and elements from the group of transition metals have been found, with boron being particularly preferred.

In a preferred embodiment of the invention, colloidal amorphous titanium hydroxide or colloidal amorphous hydrates of titanium dioxide are added to the treatment solution or suspension as precursors for the formation of anatase crystals. Only in the course of the surface reaction does anatase crystals form from these compounds. In this crystallization, a doping, for example, with boron, which is added as a network converter, carried out in situ. For this crystallization, a time of at least several minutes is required under the specified process parameters.

Generally, it should be noted that anatase is either already present in the colloidal system prior to application, or the crystals grow in or out of the melt during the sintering and melting process, which can be advantageously controlled by heat input and time. The same applies to the doping. This can be thermodynamic in the melt

Simplify processes and make them extremely efficient. The dopants can be incorporated into the structure by the melt phase or sintering reactions.

Another, independent and also generally preferred embodiment of the

The method according to the invention therefore comprises adding or removing one or more elements selected from the group consisting of fluorine, copper, silver, tin, zinc and titanium, in metallic form or in the form of a corresponding salt, to the treatment solution or suspension . become.

The inventive method using the treatment solution or suspension according to the invention leads in all its different embodiments to an article having a changed in their properties surface, which advantageously not to

Formation of an overlying layer on the object comes, which would be recognized by a phase boundary, but to a modification of the upper spatial layer of

The object itself. The modification relates to a lying on the outside of the article layer region whose transition into the object is gradual and perpendicular to the surface.

In order to prevent sedimentation and thus to increase the storage stability of the suspension, stabilizing surface-active substances or rheology additives can be used.

Suitable surfactants stabilize colloidal particles electrostatically, sterically or electrosterically; suitable dispersing additives are, for. As polyacrylic acid, modified polyacrylic acid or modified polyacrylates, for. B. available under the trade name Disperbyk 191 Fa. Byk-Chemie GmbH, or modified polyether, z. B. Tego Dispers 651 the company Evonik Tego Chemie GmbH.

Suitable rheology additives for stabilizing against sedimentation are xanthan and / or modified ureas, e.g. B. Byk 420 Fa. Byk-Chemie GmbH, proven because they cause a thixotropic behavior and thus at a suitable dosage sedimentation

prevent, but only slightly increase the processing viscosity.

It has also been found that stabilization of the treatment solution or suspension can be improved, at least in part, also by the addition of thickening agents.

Thickeners also have the property of controlling the infiltration or diffusion of the modifying constituents of the treatment solution or suspension and can, with increasing Concentration limit the penetration depth of the modifying substances in the upper spatial area of the substrate, ie with increasing proportion of thickening agent reduces the penetration depth. This leads to a significant material savings, because a modification can only be ensured up to a desired penetration depth.

A preferred treatment solution or suspension therefore generally contains, in addition to other constituents, one or more thickeners, optionally in addition to the dispersants and / or rheology additives mentioned above.

Preferably, the thickener (s) are selected from the group consisting of carboxymethyl cellulose, peptapone, xanthan, gum arabic, alginate, guar gum,

Locust bean gum, tragacanth and combinations of two or more of the same.

The particle size of a suspension in which the particles have a size distribution can be given by the average particle diameter D50.

It has been found that for the colloidal treatment solution or suspension, a mean particle diameter D50 of 0.1 nm to 500 nm, preferably 0.1 nm to 100 nm, more preferably 0.1 nm to 50 nm, gives good results. The choice of particles in this size range facilitates the penetration of the treatment solution or suspension into the pores and accelerates the surface reaction. The use of particles with a D50 of greater than 50 nm, preferably in the range from 50 nm to 2000 nm, has proved advantageous only for the anti-slip finishing of the surfaces, since the use of smaller particles does not achieve the desired microroughness. For anti-slip equipment, coarser particles, i. Particles having an average particle diameter D50 in the range of 50 to 2000 nm used in addition to the finer particles described above.

In principle, the particle size of the coarser particles in the above-mentioned range can be freely selected and, in particular, adjusted with regard to special requirements. Due to the resulting surface roughness, it is generally preferred for use of the final indoor product if the coarser, additionally contained particles have an average particle diameter D50 of 50 nm to 500 nm. As a result, a sufficient slip resistance is achieved at the same time acceptable soiling behavior. For an application of the final product in the outdoor area, where generally a stronger

Rutsschhemmung is desired and the Anschmutzverhalten is of less importance, it is generally preferred that the coarser, additionally contained particles have a medium Have particle diameter D50 from 500 nm to 2000 nm.

Due to the small particle size of the substances in the treatment solution or suspension, the pores of the surface of the substrate to be treated are first filled. In addition, it initially comes after the order to form a thin layer on the surface, which reacts in the course of the reaction during the subsequent heating. Due to the high reactivity of the ingredients with the surface and the small layer thickness are compared to classic glazes or engobes shorter burn-in times needed, which represents a significant procedural and economic advantage.

In a particularly advantageous embodiment, the invention thus relates in addition to the

described treatment solution or suspension a method for treating a surface of a mineral substrate with the method steps

Applying an aqueous or alcoholic treatment solution or suspension containing one or more network formers selected from the group consisting of Si0 ₂ , Ge0 ₂ , P ₂ O ₃ and B ₂ 0 ₃ or a precursor compound thereof, wherein the

Treatment solution or suspension colloidal particles with a medium

Particle diameter D50 from 1 nm to 2000 nm, on the mineral substrate and

• Subsequent heating of the substrate with gradual change of the surface from the outside of the substrate in the inner direction and without forming a

Phase boundary.

In another preferred embodiment of the method according to the invention, the treatment solution or suspension is prepared using 0.5 to 5% nitric acid, preferably 0.5 to 2% nitric acid, more preferably 1% nitric acid, and initially the aluminum isopropoxide was added to the nitric acid and stirred. Then the boric acid is added after 30 to 90 minutes, preferably 50 to 70 minutes.

In a further preferred embodiment of the method according to the invention, the treatment solution or suspension is generally using 0.05 to 0.10 mol / l, preferably 0.07 to 0.08 mol / l, more preferably 0.0764 mol / l, aluminum isopropoxide and from 0.10 to 0.50 mol / l, preferably 0.20 to 0.30 mol / l, more preferably 0.23 mol / l, boric acid.

The inventive treatment solution or suspension is sufficient storage stable and can be stored for several weeks to months after their preparation. The application of the same to the substrate to be treated is carried out according to conventional in the present art well-known coating methods such as spraying, dipping, rolling and printing and therefore needs no further explanation.

The application of the treatment solution or suspension according to the invention is generally carried out at a substrate temperature in the range of about room temperature to about 250 ° C, preferably to a temperature in the range of about 140 to 200 ° C, before or after

ceramic firing of the substrate. In the subsequent heat treatment, the substrate is then heated to a temperature ranging between about 350 ° C and 950 ° C, preferably to a temperature in the range of about 600, preferably after the water contained in the treating solution or suspension has been removed by drying ° C up to 850 ° C. At this temperature, the reaction of the components contained in the treating solution or suspension with the substrate occurs to form a surface layer modified from the starting substrate. Thereby migration processes within the surface, i. in the upper spatial layer area of the substrate, which lead to the formation of the changed lattice structure or the changed network. This temperature treatment is generally carried out for a period of about one minute to about 30 minutes, preferably 1 to 5 minutes.

However, the drying described above as preferred is in any case optional and does not necessarily have to be carried out as a separate process step. It may also be during the final step of heating, e.g. controlled by a corresponding temporal temperature control.

According to another, independent advantageous embodiment of the process according to the invention, the treatment solution or suspension according to the invention is applied to a green product, i. an unbaked mineral substrate, applied. Subsequently, the green compact thus treated is subjected, as usual, to a corresponding heat treatment, such as a ceramic firing. The application is carried out at a substrate temperature in the range of about room temperature to about 120 ° C. This advantageously makes it possible to completely save the energy-intensive process step of additional heat treatment, such as firing a glaze or engobe. This procedure is therefore particularly economical and resource-saving.

It has been found that application at a substrate temperature in the range of about room temperature to about 80 ° C or 200 ° C is particularly preferred in some embodiments. It has been shown that temperatures of 50, 80, 120, 140 and 200 ° C each very good Represent temperature points to control the penetration or infiltration depth. In general, the infiltration or diffusion into the substrate can advantageously be controlled by suitable choice of temperature in such a way that the penetration depth of the constituents of the treatment solution or suspension is greater at low substrate temperature and lower at higher substrate temperature. In this way, the spatial extent of the change in the surface of the substrate can be adjusted. As a result, the process can be made particularly economical, since less of the treatment solution or suspension can or must be used. Since it does not necessarily come to the absolutely exact observance of these temperatures, the resulting temperature ranges from room temperature to 50 ° C, 50 to 80 ° C, 80 to 120 ° C, 120 to 140 ° C and 140 to 200 ° C. also corresponding and particularly preferred.

In general, the penetration depth and thus the modification of the surface area can also be achieved by hydrophobing the substrate before applying the treatment solution or

Control suspension. The stronger the hydrophobization, the lower the penetration depth.

The hydrophobing of mineral substrates is in this case generally familiar to the person skilled in the art and therefore need not be explained in more detail. In general, nanoscale or nanoparticulate silicon compounds, fluoro- or alkylsilanes and the like are used for this purpose.

It should be particularly emphasized that it is the achievement of the present invention to have created a treatment solution or suspension with which it is due to the

Finest distribution of the components contained in the same is possible through the surface

To achieve changes in the (lattice) structures or the network in the uppermost region of the substrate when compared to applying a conventional coating in the form of a glaze or engobe lower temperatures and also the cost of materials significantly

reduce and, where appropriate, even completely dispense with an energy-intensive process step.

This fact, i. the change within the surface area of the substrate by the method according to the invention in comparison with the application of a coating in the form of a glaze is shown in FIGS. 1 and 2, wherein FIG. 1 shows the surface modification according to the invention and FIG. 2 represents the cited prior art ,

A molded article produced by the method of the present invention is also part of the present invention, in particular, a molded article in which the change of the surface is made gradually from the outside of the molded article in the inner direction and without trained phase boundary runs.

In a preferred embodiment, the molded article has a surface that is non-slip, anti-soiling, abrasion-optimized, scratch-resistant, heat-reflective,

Self-cleaning and / or growth inhibiting or generally designed antimicrobial.

Examples of objects according to the invention are:

• Glazed and unglazed, polished, lapped, satined floor tiles, which are protected by a

Treatment according to the invention can be improved in its slip resistance

• Wall and floor tiles have antibacterial and / or photocatalytic properties

respectively

• Sanitary ceramics have the hydrophilic and antibacterial properties

• clay ceramics such as, roof tiles or bricks that are permanently protected against fouling

• Facade tiles, façade glasses that are permanently protected against fouling and have a permanently hydrophilic, photocatalytically active surface

• Heat-reflecting floor coverings, wall coverings and façades made of ceramic, glass or natural stone

• Flat glass, in particular single-pane safety glass

The above list is not exhaustive and several other advantageous applications are possible. Of particular note is generally an increase in the gloss level of ceramic surfaces. Without being limited to one or this specific embodiment, the gloss increase in digital printing can be mentioned as a particular example, since in this case used inks produce only partially high-gloss surfaces. The application is basically possible for every ceramic substrate.

Treatment solutions or suspensions applied prior to ceramic firing may cause this effect of increasing the gloss level when e.g. PbO, usually in low concentrations, included as a network converter. Also an increased share of

Melt-phase producing alkalis or alkaline-earth oxides increase the gloss level compared to other glazes in that they set in early and more intense

Lead melt phase reactions. This in turn results in a smoothing of the surface, which causes less diffuse reflection of the light.

It is also possible to increase the refractoriness of the cullet. This is effected generally by increasing the proportion of acting as a hardener network modifiers such as FeO, Fe ₂ 0 _3, CaC0 _3, Ca ₃ (P0 ₄₎ 2 and Al ₂ 0. ₃ As a result, the melt phase formation is reduced and a higher resistance to fire is achieved. Also known as fumed silica nanoparticles aerosils with a particle size in the range of 7 nm can be used for this purpose. Alternatively, network converters contained in the ceramic or green compact can be bound by a correspondingly high proportion of network formers in the treatment solution or suspension and lead to reduced melt phase formation.

Another example is that of a ceramic by targeted formation of minerals like

For example, cordierite refractory properties can be imparted. In general, its formation in conventional procedure in the shards is very slow and sluggish and requires high firing temperatures and long holding times. With the inventive

Treatment solution or suspension can, after prior analysis of the ceramic, the proportion of Si0 ₂ , Al ₂ 0 ₃ and MgO, for example by selective addition of magnesium-containing

Precursor compounds are targeted to the formation of cordierite-silicates. The

Magnesium acts as a network transducer here and the nanoscale size of the Mg ion favors the integration into the network. Melt-phase processes and eutectics are achieved very rapidly, since with lower activation energy, the network is also set in motion by vibrating the magnesium.

By treating glass surfaces, in particular float glass, or surfaces of glazes with the inventive treatment solution or suspension, the

Increase the strength of the glass and cause an anti-fingerprint effect. Here, cracks, pores and voids are melted down and thus repaired in a cloying way. It will be at the

Production, resulting surface defects (such as cracks), which are responsible for the low strength, fixed. These errors already arise where the glass comes into contact with a tool for the first time. By chemical processes can then

Crack speed can be controlled. For example, water can diffuse from the air to the crack tip and dissolve bonds. To prevent the formation of cracks, for example, the glass or glaze surface is treated with a treatment solution or suspension which reacts with silicate glasses. As a result, the said damage or defects are filled and solidified under high temperatures. The formation of melt phases and reaction with the present as a substrate glass or the glaze, the surface defects are corrected and there is a smoothing effect, for example, sandblasted glass surfaces, which additionally gives anti-fingerprint properties.

In principle, the process according to the invention can also be integrated directly into the production process when using glass as substrate by applying the treatment solution or suspension according to the invention during the cooling phase at a substrate temperature which corresponds approximately to the softening temperature of the glass. This is particularly advantageous in the case of the so-called float glass method, since the formation of surface defects such as cracks and the like can thus already be avoided or prevented in the production process. Of course, the application of the treatment solution or suspension may also be at lower temperatures, e.g. at temperatures ranging from room temperature to 200 ° C. In order to bring about a corresponding reaction with the network of the substrate, however, a heating to a temperature in the softening range of the respective glass is then required. Depending on the type of glass, this temperature may be in the range of about 450 to about 900 ° C, with deviations from this range in special

Glass compositions are quite possible.

Likewise, through targeted use of network transducers on the surface of the glazes the emergence of finest pinholes can be avoided or prevented because the glaze can degas better or faster, easier or longer.

By using Si0 ₂ , Al ₂ 0 ₃ and B ₂ 0 ₃ as a network former, the mechanical strength is increased. Likewise, B ₂ 0 _{3 is} acid-resistant. In the case of Ti0 ₂ , the acid resistance is increased, in Zr0 ₂ the chemical resistance and with ZnO the hardness is increased. Other network formers or converters which are used to increase the strength and UV transparency are P ₂ O ₅ , Li ₂ O, Na ₂ O, K ₂ O, CaO and MgO.

Furthermore, according to the invention, modification and adaptation of surface tensions of ceramic cullet or glazes can be effected. This is interesting for example for ceramic surfaces that are to be glazed, and this is only possible with difficulty due to surface tensions, which can cause, for example, chipping of glazes, lack of frost resistance. Thus, for example, the coefficient of expansion of the ceramic base body can be modified by infiltration of, for example, Al ₂ O ₃ or Si0 ₂ in one or the other direction. The materials which have a very high resistance to thermal shock (in the height of about 1400 ° C), therefore, on porous glass ceramics with low thermal Expansion coefficients built up. They are based on cordierite, celsian, ß-spodumene and mullite. The magnesium barium silicate phase (MgO, Si0 ₂ , BaO) in the treatment solution is intended for the high thermal expansion coefficient and for temperatures above 700 ° C. In addition, the addition of both fluorides and nitrides and ZnO cause the same effect.

The same applies to glazes. Due to the nanoscale size, the expansion-determining ions can be distributed very evenly, react even at low additions very intense, so that other disadvantages such. Color changes etc. are avoided.

Another is the closing of surface pores in the direction of optimizing

Pollution tendency of polished, lapped and satin surfaces to call. This can be caused by targeted infiltration of the surfaces, as can be achieved by targeted

Melt phase processes pores can be closed, which would then not be disclosed again in the subsequent polishing process and thus lead to increased dirt problem.

A targeted channeling in glazes is possible. In this process, open-pored structures are created in the glaze, which give the ice the opportunity to expand during frost-free changes and thus prevent the destruction of the ceramic.

Coloring additives such as u.a. Ti, V, Fe, Cr, Mn, Co, Ni and Cu to be infiltrated

Aggregates allow dyeing or staining of shards. If through-dyeing is even desired, this is done by applying one or more times

Treatment solution or suspension on a green body, preferably at room temperature. If through-dyeing is not desired, then a suitable substrate temperature or a corresponding hydrophobization is selected as pre-treatment before application. Also in this case, the coloring of already fired ceramic substrates is to be cited, in which the penetration or infiltation depth is naturally not as high as in a green compact. A particular advantage results from the possible use of Ti0 ₂ as a substitute for the much more expensive Zr0 ₂ , which must be added to the ceramic base to achieve a pure white coloring or coloring. This preference is further enhanced by the fact that generally a white coloration of the uppermost spatial region of the substrate is usually sufficient, while the Zr0 ₂ must be present in the entire body, as a corresponding color only the upper or outer region of the ceramic shards is not possible. A mofification toward pure white can be achieved in which 0.5-3% TiO ₂ and / or a precursor thereof, infiltrated: As already mentioned, this saves the use of expensive Zr0 ₂ in the mass; The same can of course be done in any color, depending on which coloring components or elements you add.

Finally, the targeted Oberflächenporosierung of ceramic shards or separation shelves for generating a heat diffusion barrier is to be mentioned. Of particular importance here is the porosity of the separating gangs, as a result of which the ceramic body is decoupled from the glaze and the low thermal conductivity leads to a lower one

Heat loss in the tile.

This can be done by defined formation of certain (layer) minerals, on the one hand show a low thermal conductivity and are generated selectively wet-chemical and even have an open-pored structure, which in turn does not forward the heat.

It is also possible to deliberately incorporate a "thermal barrier" or heat-insulating layer by the choice of pore-forming reactions The reactions leading to the porous structures, such as wood-like structures or zeolitic structures, are based, for example, on the addition of lignosulfonic acid, carboxymethylcellulose and aluminates.

Porous materials of inorganic nature, such as perlite or aluminum hydroxide, or organic nature, such as naphthalene, also known as a porosity agent can be used to the

Influence pore structure.

Another example is the production of color-changing glazes whose color change is due to heat input. This is important for building applications where the building should not heat up so much. This is effected by infiltration of glazes with certain ions / atoms which change color upon heat.

The addition of color pigment, sodalite and the use of hydrochromic (which change their color to moisture), photochromic (which react to UV light such as sunlight) and

Thermochromic dyes such as cobalt (II) chloride (which are temperature dependent) allow for high heat generation. Here, the dyes are enclosed in microcapsules. Within these microcapsules, the change from solid to liquid takes place. The microcapsules change color so that the entire material appears in a different form.

By ions of the transition elements, the color change can also arise. The ions are in the glaze dissolved. The color comes about through electron transitions within the band scheme of an ion. The transition metal ions have several higher order bands. When a photon encounters an ion, an electron is excited from the inner shell and reaches a higher orbit. Since each wavelength corresponds to a color, the absorption of the light causes the color change. The following coloring ions and their colors are basically important: Ti (III) / violet, V (III) / green, V (V) / colorless, Cr (III) / green, Cr (VI) / yellow, Mn ( II) / colorless, Mn (III) / violet, Fe (II) / blue, Fe (III) / yellow, Co (II) / blue-pink, Co (III) / green, Ni (II) / blue-yellow , Cu (l) / colorless and Cu (ll) / blue.

All the examples described can be carried out with the method according to the invention, this generally being based on the modification of the upper or outer region of the substrate, which by targeted use of network converters in fired substrates or glass

Penetration of 2 μηι or more allows. This could be demonstrated by electron microscopy and by appropriate elemental analysis. At the same time, the infiltration depth, in particular when applied to a green compact, can be controlled by the substrate temperature during application or corresponding hydrophobing. If desired, a green compact can also be completely penetrated.

Even if generally comparatively short periods of temperature treatment are desired, in individual cases, especially when green compacts are used as substrate,

Treatment times of up to 48 hours may be preferred.

In summary, the present invention advantageously makes it possible to modify the surface of a mineral substrate in which no interface between the surface and the object is formed. In addition to the advantages already mentioned, this avoids the disadvantages of a coating that can be undermined or flake off or rubbed off under mechanical stress of the object. The inventive method is extremely variable, since the inventive treatment solution or

Suspension can be provided with a variety of functional additives

Different effects and effects can be achieved or adapted to a variety of substrates.

Another advantage is that the appearance or the visual appearance of the layer is not changed. On the one hand, the modified surface layer is very homogeneous in itself, so that there is no turbidity, on the other hand, the absence of an interface between coating and object avoids unwanted reflections. Possible differences in

Refractive index are gradual and perpendicular to the surface. Finally, it should be noted that the application of liquids and subsequent thermal treatment is standard in the ceramics industry. Thus, no additional systems for reworking or additional, complex process steps must be performed.

The invention generally described above will be described in more detail below with reference to specific embodiments for better understanding. As with all% data in the description, the corresponding details in the examples and in the appended claims are by weight unless otherwise stated.

General process description:

On tiles, z. B. directly after the ceramic firing, an inventive

Applied treatment solution or suspension. This can be done by spray application with standard paint sprayers. Subsequently, a renewed

Temperature treatment for a period of one to 30 minutes, preferably at 1 to 5 minutes, at 500 to 950 ° C, preferably at 600 to 850 ° C. It is advantageous to coat the article generally at a temperature in the range of 0 ° C to 250 ° C. Particularly preferably, the substrate is brought by heating to a temperature up to 120 ° C, or after the

ceramic firing by cooling, to a temperature of 140 ° C to 200 ° C before the

Treatment solution or suspension is applied.

Examples

example 1

15.6 g (0.0764 mol) are added with stirring to 1 liter of 1% nitric acid.

Aluminum isopropoxide is added and the mixture is stirred further. After one hour, 14.2 g (0.230 mol) of boric acid are added. This suspension of reactive substances is suitable for the treatment of a tile with glaze or ceramic and can be mixed with other functional substances.

Example 2

In the suspension of Example 1, in addition 0.35 g of copper (II) chloride dihydrate are dissolved. The mixture is applied by means of a flow cup gun with an atomization pressure of 6 bar with about 20g / m ² to 150 ° C hot tiles. After 10 minutes of temperature treatment at 950 ° C a tile is obtained, which permanently against the growth of moss and against microbiological

Settlement is protected. Example 3

3.2 g of a suspension of titanium dioxide (Aerodisp W 740 X, Evonik) are additionally added per liter to the coating suspension from Example 1 with stirring. Then proceed as in Example 2. The result is a tile that is not only permanently improved in its slip resistance, but also permanently hydrophilic and thus easier to clean.

Aerodisp W 740 X: Colloidal Ti0 ₂ in water with an average particle size of <100 nm and a solids content of 40%

Example 4

20 g of zirconium n-propoxide are additionally added per liter to the coating suspension from Example 1 and stirred, initially forming a precipitate, which, however, dissolves again on further stirring. The application of this suspension is analogous to Example 2. A correspondingly equipped tile with silicate glaze has a reduced

Surface roughness and improved scratch resistance.

Example 5

13.6 g of indium (III) nitrate hydrate (0.043 mol) are added with stirring to a 1 liter of 1% hydrochloric acid and stirred. Subsequently, 14.2 g (0.230 mol) of boric acid and 4.3 g (0.023 mol) of Sn (II) chloride are added and stirring is continued. The suspension can be applied analogously to Example 2 on tiles with silicate glaze and provides surfaces with increased heat reflection.

Example 6

10 g of titanium oxide sulfate are dissolved in one liter of distilled water. Then slowly 25% ammonia solution is added until the titanium precipitates as hydroxide or hydrated Ti0 ₂ at pH 8-9 as a white precipitate. The precipitate can be separated by filtration and washed with distilled water and then taken up in 1 liter of 1% nitric acid and redispersed by heating to 80 ° C. for several hours. After cooling, 15.6 g (0.0764 mol) of aluminum isopropoxide and 14.2 g (0.230 mol) of boric acid are added with stirring as in Example 1. The coating suspension is applied as described in Example 2 and leads to photocatalytically active, hydrophilic layers. Example 7

For the treatment of a silicon-free surface, a commercially available silica sol, e.g. Levasil 300/30%, Akzo Nobel, adjusted to a solids content of 2%. To one liter of this suspension, 8.7 g (0.0426 mol) of aluminum isopropoxide and 12.6 g (0.204 mol) of boric acid are added and stirred for about one hour. The coating suspension can be applied as in Example 2.

Example 8

13.6 g of indium (III) nitrate hydrate (0.043 mol) are added with stirring to 1 liter of 1% hydrochloric acid and stirred. Subsequently, 14.2 g (0.230 mol) of boric acid and 4.3 g (0.023 mol) of Sn (II) chloride are added and stirring is continued. Then the addition of 8.4 g (0.040 mol) of tetraethyl orthosilicate and the solution is stirred for four hours. The resulting suspension can be applied analogously to Example 2 on tiles with silicate glaze and supplies

Surfaces with increased heat reflection.

Claims

claims

1 . Process for treating a surface of a mineral substrate with the

Steps:

Application of a treatment solution or suspension containing one or more network formers selected from the group consisting of Si0 ₂ , Ge0 ₂ , P ₂ O 5 and B ₂ 0 ₃ or a precursor compound thereof, wherein the treatment solution or suspension comprises colloidal particles having a medium Particle diameter D50 from 0.1 nm to 2000 nm, on the mineral substrate and

then heating the substrate while gradually changing the surface from the outside of the substrate in the inner direction and without forming a

Phase boundary.

2. The method according to claim 1, characterized in that the treatment solution or suspension further comprises one or more stabilizers and / or network converter selected from the group consisting of Al ₂ 0 ₃ , SnO, Ti0 ₂ , Zr0 ₂ , FeO, Fe ₂ 0 ₃ , PbO, MnO, BaO, CaO, K ₂ O, Li ₂ O and Na ₂ O or a precursor compound thereof.

3. The method according to claim 1 or 2, characterized in that the treatment solution or suspension further comprises one or more functionalizing compounds selected from the group consisting of Mo0 ₂ , Nb ₂ 0 ₅ , ZnO, ln ₂ 0 ₃ , InO, BN _X , AIN _X and Si ₃ N ₄ or precursor compounds of these compounds.

4. The method according to any one of claims 1 to 3, characterized in that the

Treatment solution or suspension further comprises one or more elements selected from the group consisting of copper, silver, tin, zinc and titanium, in metallic form or in the form of a corresponding salt.

5. The method according to any one of claims 1 to 4, characterized in that the

Treatment solution or suspension of an aqueous or alcoholic medium is formed.

A method according to any one of claims 1 to 5, characterized in that the

Treatment solution or suspension further nitric acid and / or

Contains aluminum isopropoxide and / or dispersing and / or rheology additives.

7. The method according to any one of claims 1 to 6, characterized in that

Treatment solution or suspension contains one or more thickening agents.

8. The method according to one of claims 1 to 7, characterized in that the colloidal particles contained in the treatment solution or suspension have an average particle diameter D50 of 0, 1 nm to 500 nm, in particular from 0, 1 nm to 50 nm.

9. The method according to any one of claims 1 to 8, characterized in that in the

Treatment solution or suspension colloidal particles with a medium

Particle diameter D50 from 0, 1 nm to 50 nm in addition to colloidal particles having a mean particle diameter D50 of 50 nm to 500 nm or 500 nm to 2000 nm are included.

10. The method according to any one of claims 1 to 9, characterized in that mineral substrate is hydrophobic before applying the treatment solution or suspension.

11. Method according to one of claims 1 to 10, characterized in that the

Netwerkbildner, stabilizers and / or network converters and optionally contained other metals or metal compounds in the treatment solution or suspension in a proportion of 0.05 to 10 wt .-% are included, preferably in a proportion of 0, 1 to 7 wt. %.

12. The method according to any one of claims 1 to 11, characterized in that the

Treatment solution or suspension at a substrate temperature in the range of

Room temperature to 250 ° C, preferably at a substrate temperature of 140 to 200 ° C, before or after the ceramic firing of the substrate is applied to the same.

13. The method according to any one of claims 1 to 11, characterized in that the

Treatment solution or suspension at a substrate temperature in the range of

Room temperature to 140 ° C before the ceramic firing of the substrate is applied to the same and the heating is a ceramic firing.

14. The method according to any one of claims 1 to 13, characterized in that the

mineral substrate is dried after application of the treatment solution or suspension.

15. The method according to any one of claims 1 to 12 or 14, characterized in that the heating of the substrate with the treatment solution applied thereto or

-Suspension to a temperature in the range of 350 to 950 ° C, preferably to a Temperature in the range of 600 to 850 ° C.

16. The method according to any one of claims 1 to 15, characterized in that tiles, bricks, tiles, glass, glass, concrete, ceramic, sanitary ware and / or stoneware can be used as a substrate.

17. A molded article prepared by a method of claims 1 to 16.

18. Shaped article according to claim 17, characterized in that the change of the surface is gradual from the outside of the molded article in the inner direction and without formed phase boundary.

19. Shaped article according to claim 17 or 18, characterized in that the

Molded article has a surface which is non-slip, anti-soiling, abrasion-optimized, scratch-resistant, heat-reflecting, self-cleaning, antimicrobial and / or anti-fouling, crack-caking, color-providing, hydrophilic, non-fogging,

increased gloss, with increased resistance to fire, with antifinger printing properties, with adapted surface tensions in base body and / or overlying glaze, with channeling in glazes, with porosation of separation gobs / glazes, or color change of surfaces is formed.