Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5022—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with vitreous materials
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
  • C04B41/81—Coating or impregnation
  • C04B41/85—Coating or impregnation with inorganic materials
  • C04B41/86—Glazes; Cold glazes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/03—Powdery paints
  • C09D5/033—Powdery paints characterised by the additives
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
  • C23D5/00—Coating with enamels or vitreous layers
  • C23D5/04—Coating with enamels or vitreous layers by dry methods

Definitions

• the invention is directed to a coating powder for the electrostatic coating of glass and ceramic and metallic substrates;
• the main component of the coating powder is a powdery material that forms a layer of glass when fired.
• Another object of the invention is directed to a method for producing the coating powder.
• Another object of the invention relates to the use of the coating powder for glazing, engobing and
• aqueous slurries are used; after the application of the slip, the substrate coated with it is fired, the burnable material contained in the slip melting or sintering into a glassy layer, often also referred to as a ceramic layer.
• electrostatic powder coating is becoming increasingly important. It is known that coating powders, which form a glassy layer when fired, can be sprayed electrostatically onto glass as well as ceramic and metallic surfaces.
• the electrostatically applicable coating powders must have a sufficiently high specific electrical volume resistance -
• the coating powders are coated with insulating substances, for example silanols and organopolysiloxanes,
• WO 94/26679 teaches an improvement in the adhesive and grip strength of an electrostatically applied glaze powder: in addition to a glaze powder, the coating powder also contains adhesives which burn without residue during the fire, such as polyolefins or dextrins, which are activated thermally or by moisture around the particles of the layer to fix with each other and with the substrate.
• adhesives which burn without residue during the fire, such as polyolefins or dextrins, which are activated thermally or by moisture around the particles of the layer to fix with each other and with the substrate.
• Polysiloxane-coated glass frits mixed with 10 to 15% by weight thermoplastic or 5 to 10% by weight dextrin. It is only possible to obtain glazes that can be used on porcelain bisque shards under particularly optimized conditions, which, however, lead to a high level of effort. Under Even slightly modified conditions, depending on the substrate, sometimes lead to significant glaze defects and faults before the required layer thickness is reached.
• WO 97/08115 teaches an improvement of the aforementioned problems: by using a glaze or engobe composition with a certain grain distribution, namely ad 50 value of 5 to 25 ⁇ m, ad 90 value of less than 35 ⁇ m and ad 10 Value equal to or greater than 2 ⁇ m in an additional one containing an adhesive
• Coating powder it is possible to simplify the manufacturing process without sacrificing the quality of the glaze.
• WO 97/08115 also shows that, in the absence of an organopolysiloxane, the specific electrical resistance of the coating powder increases in the desired manner with increasing amount of adhesive. Above a certain amount of adhesive, however, there are back-spray effects, so that the required layer thickness can no longer be applied, so that the baked layer is too thin and accordingly has defects.
• a problem with the electrostatic coating of glass and ceramic substrates is also that the coating powders have a very different specific volume resistance depending on their composition and their grain spectrum.
• the coating substrates have a very different and additionally depend on the climatic conditions in the coating chamber Have surface conductivity.
• a trouble-free electrostatic coating requires that the volume resistivity of the coating powder is matched to the substrate to be coated and the climatic conditions.
• the object of the present invention is accordingly to show a new way to adjust the volume resistivity of a coating powder in a simple manner so that it can be applied electrostatically without problems and leads to flawless baked coatings.
• Volume resistance of coating powders can be used. Already by adding a very small amount of a carboxylic acid salt, for example 0.05% by weight of magnesium acetate, it is possible to increase the volume resistivity of a glaze powder by 2 to 3 powers of ten.
• the invention accordingly relates to
• Coating powder for the electrostatic coating of glass and ceramic and metallic substrates comprising a powdery material which forms a glass layer when fired and which is characterized in that it contains a salt of a carboxylic acid in an amount of 0.01 to 1% by weight.
• the carboxylic acid salts are based on an aliphatic or aromatic carboxylic acid with one or more carboxyl groups and optionally also other functional groups, such as hydroxyl groups.
• Aliphatic carboxylic acids having 1 to 6 carbon atoms and 1 to 2 carboxyl groups and optionally 1 or 2 other functional groups are preferred.
• Lower aliphatic monocarboxylic acids, in particular acetic acid and propionic acid, are particularly suitable.
• the choice of the cation of the carboxylic acid salt includes metals of the main and sub-groups of the periodic
• Alkaline earth metal or earth metal cation particularly preferably around L ⁇ i • +, N ⁇ a +, -K- +, -M.g2 +, C_a2 + and ⁇ A_ -I3 +.
• carboxylic acid salt increases the resistance of the coating powder.
• an amount below 0.01% by weight has an effect, the amount used in practice will be around and in particular above 0.01% by weight.
• the amount used is expediently in the range from 0.01 to 1% by weight. It is possible to use more than 1% by weight, but then there is no further increase in the specific electrical resistance.
• Preferably 0.05 to 0.5 wt .-% carboxylic acid salt, in particular an alkali, alkaline earth or earth metal acetate or propionate are used.
• the carboxylic acid salt must be distributed homogeneously in the coating powder. Such a distribution can be achieved in a simple manner by intensive dry mixing, in particular using an intensive mixer.
• the glass-layer-forming powdery material can be contacted with an aqueous solution or suspension of a carboxylic acid salt, for example in the course of a grinding process, whereupon the moist product is dried and further sifted if necessary.
• volume resistance of coating powders significantly, namely to increase by several powers of ten, usually 3 to 5 powers of ten. This achieves resistance values as required for electrostatic application. While, for example, untreated glaze powder usually has a specific electrical
• 'Have resistance in the range of 10 to 10 ohm m can be achieved by adding 0.1 to 0.3 wt .-% of an acetate resistance values in the range of 10 to 10 ohms "m. Treatment with organopolysiloxanes to resistance increase is thus generally no longer required, but it is not excluded if resistance above that available with the carboxylic acid salt is required.
• the coating powder according to the invention can additionally contain an effective amount of a powdery adhesive which can be activated physically, in particular thermally, namely by melting and solidification, or chemically.
• Adhesives which can be activated thermally are in particular thermoplastics, such as polyethylene, the binding effect of which is achieved by melting with subsequent solidification.
• the substrate to be coated is heated to a temperature above the melting point of the thermoplastic before and / or after coating.
• the chemically activatable adhesives include two-component resin systems, such as the epoxy resin hardener combinations and isocyanate hardener combinations.
• the amount of adhesive is usually in the range from 1 to 20% by weight, based on the coating powder, but in particular from 1 to 10% by weight.
• the adhesive is introduced into the coating powder in a known manner before, during or after the dry addition of the carboxylic acid salt.
• intensive mixing below the activation temperature of the adhesive is advisable in order to ensure a homogeneous distribution and thus an error-free coating before and after the fire.
• the adhesive strength can also be improved by using a pulverulent material which forms a glass layer during the fire and has a specific grain spectrum, in particular d 50 5 to 25 ⁇ m, d 90 less than 35 ⁇ m and d 10 equal to or greater than 2 ⁇ m.
• a pulverulent material which forms a glass layer during the fire and has a specific grain spectrum, in particular d 50 5 to 25 ⁇ m, d 90 less than 35 ⁇ m and d 10 equal to or greater than 2 ⁇ m.
• the carboxylic acid salt Before or after the addition of the carboxylic acid salt to the powdery material, this must be ground and / or sifted if necessary.
• the material that forms a layer of glass in the fire is essentially glaze, engobe,
• Glass enamel and decorative powder as well as enamel powder can be essentially uniform substances, such as glass frits or mixtures of glass frits, or mixtures of substances: glaze powder consisting essentially of one or more glass frits and, if appropriate, additional substances from the series clay, wollastonite, zirconium silicate and white or colored pigments; Glass enamel powder consisting essentially of one or more glass frits or so-called rivers and pigments; Engobes containing, in addition to glass frits, substances from the range of fine-particle ceramic raw materials, ground minerals, glass and porcelain flour, opacifiers and pigments.
• the glass layer-forming materials are preferably already in the coating powder in the fritted state in an amount of 30 to 100% by weight, in particular more than 50% by weight.
• the electrostatically coated substrates are fired immediately or after further surface decoration, for example comprising fixing the layer using a polymeric fixing agent and decoration using a decal or by means of screen printing.
• the firing temperature and duration depend on the substrate and the type of coating powder. For example, it can be a typical decorative firing or a one-time rapid firing, the unfired substrate and the applied coating being fired at the same time.
• these additives in electrostatically applicable coating powders can also be customary fluidizing agents, such as pyrogenic oxides, for example Si0 2 , A1 2 0 3 , Ti0 2 , Zr0 2 in an effective amount, about 0.05 to 3% by weight, in particular 0.1 to 0.5 wt .-%, which improves the electrostatic spraying of the powder.
• pyrogenic oxides for example Si0 2 , A1 2 0 3 , Ti0 2 , Zr0 2 in an effective amount, about 0.05 to 3% by weight, in particular 0.1 to 0.5 wt .-%, which improves the electrostatic spraying of the powder.
• the coating powder according to the invention can be used for glazing, engobing, enamelling and decorating Use fired and unfired ceramic substrates and glass as well as for enamelling metals.
• Use includes electrostatic coating under known conditions and firing the substrate.
• Coating powder is aimed at the production of glass decorations, in particular imitation etchings or colored high-gloss decorations, which are provided with additional decor, such as lettering.
• decorations of this type for example imitation etching with additional decoration, were produced using polymer systems which made two fires necessary.
• coating powders with a carboxylic acid salt such decorations can also be obtained using other coating powders which can be applied electrostatically and whose specific resistance is sufficiently high, for example those which contain polysiloxanes.
• an electrostatically administrable coating powder particularly such microns with a d 50 value of below 10 and an electrical resistivity of about 10 ohms "m, preferably 10 m to 10 Ohm ', electrostatically pre-heated in such an amount to a Glass (100 to 250 ° C) sprayed that the
• Layer thickness after baking is 10 to 50 ⁇ m.
• the coating can be fixed in a known manner by spraying using a polymer dispersion.
• the fixed layer can be applied in a known manner, for example by means of Screen printing or decal technique, a decor can be applied. This is followed by the fire, whereby the basic decor, such as the imitation of etching, and the additional decor are burned in at the same time.
• the coating powder contains an opacifier, such as Si0 2 , ZrSi0 4 , Ti0 2 , Zr0 2 and spinel, or multi-phase glass systems.
• the coating powder contains a carboxylic acid salt and / or an organopolysiloxane and / or an organic adhesive and / or a fluidizing agent, which itself can act as an opacifying agent, in an effective amount.
• the d 50 value of the powder is preferably around / below 5 ⁇ m and the d 90 value below the value of the baked layer.
• the carboxylic acid salts in the coating powder also do not lead to any defects in the baked coating.
• coating powders according to the invention which additionally contain an adhesive with a high specific electrical resistance, is that there is no electrostatically induced segregation during electrical coating, which could previously result in the coated substrate containing a higher proportion of adhesive than that Powder that did not hit the substrate when sprayed. Separation is obviously avoided because the specific electrical resistance of the glass-forming material is similar to that of the adhesive.
• Adhesive content is therefore eliminated when using the powder according to the invention.
• coating powders according to the invention is that the fluidizability is improved by covering active centers of the glass-forming material with a carboxylic acid salt. This means that the addition of other fluidizing agents can be dispensed with and the appearance of haze on a baked coating on glass is avoided.
• the invention is further illustrated by the following examples and comparative examples.
• a frit without carboxylic acid salt or a frit with carboxylic acid salt - produced according to a) - was mixed intensively with the adhesive by homogenizing the respective raw mixture using an intensive mixing device.
• Polyethylene wax with a softening temperature of 135 ° C. and a particle size range d 10 1.8 ⁇ m, d 50 10.5 ⁇ m and d 90 16.9 ⁇ m was used as the adhesive.
• volume resistance of the coating powder measurement method and equipment according to DIN IEC 93:
• the measuring voltage was always connected 1 minute after filling the powder sample into the measuring cell (to ensure constant and reproducible bulk densities in the
• the measured value was read 1 minute after the measuring voltage was switched on.
• Electrostatic coating Bisquit-fired porcelain fragments (15 x 15 cm) were coated without preheating. High-voltage gun with flat jet nozzle; 70 kV at 60 ⁇ A.
• a glass frit - TGF 2486 A der - was used to produce a glaze coating powder for tiles
• the company Cerdec AG containing Si0 2 , ZnO, B 2 0 3 , A1 2 0 3 , MgO, CaO, K 2 0 and Zr0 2 as main components (sample 1.1).
• Example 1.2 Analogous to general regulation a), but on a 150-fold scale, a grinding time of 75 minutes in a ball drum mill and drum drying, the frit was coated with 0.2% by weight of magnesium acetate (sample 1.2); Sample 1.1 corresponds to the frit treated in the same way in the absence of magnesium acetate.
• Sample 1.2 was sighted (Sample 1.3).
• Table 1 shows the specific electrical resistance and the grain spectrum of the samples.
• the coating powders 1.1 and 1.2 of Example 1 and coating powders 1.1 H and 1.2 H containing polyethylene wax as adhesives were applied electrostatically to bisque-fired porcelain fragments in accordance with general rule d), and the coated fragments were then fired.
• Samples 1.1 H and 1.2 H were produced in accordance with general regulation b), the amount of adhesive in each case being 6% by weight, based on the coating powder.
• the adhesive strength was determined in% (average of 5 measurements) according to general regulation e) as well as the application quantity per 60 seconds (average of 5 measurements) and also the specific electrical volume resistance according to general regulation c), as well as the surface quality within 60 minutes Baked glaze at 1170 ° C. The results follow from Table 2.
• **) good smooth and calm surface; no pinpricks, no orange peel effect; no unwinder (bubbles, unglazed areas).
• a glaze frit (TGF 2486 A from Cerdec AG) was coated with different amounts of magnesium acetate in accordance with general regulation a).
• Sample 3.0 corresponds to the frit treated according to a) in the absence of magnesium acetate; Grain spectrum of 3.0: d 10 1.2 ⁇ m, d 50 8.6 ⁇ m, d 90 34.9 ⁇ m.
• Table 3 shows, the specific increases electrical volume resistance of the coating powder increases strongly with increasing amount of Mg acetate.
• Example 4 Analogously to Example 3, according to general rule a), different salts were applied to the same glass frit (290/498 from Cerdec AG), in each case in an amount of 0.2% by weight.
• Table 4 shows the specific electrical volume resistance of the various powders, the powder No. 4.0 containing no salt and the powder No. 4.1 to 4.8 according to the invention. Powder Nos. 4.9 to 4.11 contain salts other than carboxylic acid salts (not according to the invention), which lead to little or no increase in resistance. Table 4

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Ceramic Engineering (AREA)
• Structural Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Wood Science & Technology (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Surface Treatment Of Glass (AREA)
• Glass Compositions (AREA)

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• 1997
  • 1997-05-28 DE DE19722273A patent/DE19722273A1/de not_active Withdrawn
• 1998
  • 1998-05-06 TR TR1999/02889T patent/TR199902889T2/xx unknown
  • 1998-05-06 WO PCT/EP1998/002659 patent/WO1998054105A1/de not_active Ceased
  • 1998-05-06 JP JP11500143A patent/JP2000516905A/ja active Pending
  • 1998-05-06 BR BR9809690-7A patent/BR9809690A/pt not_active IP Right Cessation
  • 1998-05-06 US US09/424,640 patent/US6270854B1/en not_active Expired - Fee Related
  • 1998-05-06 EP EP98929283A patent/EP0984904A1/de not_active Ceased

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