CS272995B1 - White titanium powder-like enamel for dry application in electric field - Google Patents

Abstract

The white titanium powdered enamel contains by weight 3.l to 6 % aluminium oxide, 38 to 46 % silicic oxide, 12 to 18 % boric oxide, 6 to 9 % sodium oxide, 4 to 8 % potassium oxide, 0.l to 1 % lithium oxide, 0.8 to l.6 % magnesium oxide, 16 to 20 % titanium oxide, 1.5 to 3 % phosphoric oxide, up to 2 % sodium fluoride and 4 to 7.5 % sodium fluorosilicate. The advantage of this powdered enamel is the greater possibilities of its use, whether directly on metal material, on metal material with a baked film of undercoat enamel, or while maintaining specified preconditions on an unbaked film of electro-statically applied undercoat enamel.

Description

The invention relates to a white titanium powder enamel for dry application in an electric field to a metal substrate.

The enamel coatings with white enamel have hitherto been formed mostly in a wet manner in which an enamel suspension is applied to a metal or fired base. This suspension is prepared by wet grinding the respective enamel frit and suspending additive. The suspension thus prepared is applied either directly to the metal with a special surface pretreatment or to the fired base enamel and, after drying, fired. The enamelling process in this way is also complicated by the fact that the applied suspension must be dried and the uniformity of the coating is strongly dependent on the precision of the operation. The white enamel applied by the wet method is mostly applied by spraying, which leads to considerable material losses and the free silica content of the suspending additives makes the working environment unhealthy.

This disadvantage is overcome by the white titanium powder enamel according to the invention, which comprises from 3.1 to 6.00% by weight of alumina, up to 46% of silica, 12 to 18% of boron oxide, 6 to 9% of sodium oxide, 4 to 8% potassium oxide, 0.1 to 1% lithium oxide, 0.8 to 1.6% magnesium oxide, 16 to 20% titanium dioxide 1.5 to 3% phosphorus pentoxide, up to 2% sodium fluoride, and 4 to 8% 7.5% sodium fluorosilicate. First, the enamel frit of the chemical composition is melted within the above tolerances, and after drying it is ground in a manner corresponding to the process described in AO no. 194 608.

The powdered enamel thus prepared according to the invention allows the formation of enamel coatings in one or more layers on a steel panel or on baked base enamel without the use of further additives and without performing any other preparatory operations for its application in the electric field. The enamel coating thus prepared is, after firing at a temperature of 800 ° C, harmless to health and has better chemical and physical properties than a coating prepared by a wet process. This enamel is particularly suitable for the application of a bilayer system by applying it to an unburned base enamel layer whose chemical composition corresponds to AO No. 230896 and after the application of white enamel, the layers are co-baked. Due to the considerable difference in viscosities between the two enamels at 800 ° C, where the viscosity of the unburned base enamel is at least 100 cP lower, the surface of the white enamel is calmed without the typical defects that tend to be associated with other types of enamels.

Example 1

A white titanium frit for the preparation of white powdered enamel is prepared by melting at 1250 ° C from the following raw materials listed in the weight percentages:

ai ₂ o ₃ - alumina 3.90 Si0 ₂ - silicon dioxide 40,10 ^B 3 ° 3 - boron trioxide 15.20 At ₂ 0 - sodium oxide 8.10 ε, ο - potassium oxide 4.60 Li ₂ 0 - Lithium oxide 0.40 MgO - magnesium oxide 1.00 Ti0 ₂ - titanium dioxide 17.70 ^P 2 ° 5 - phosphorus pentoxide 2.10 PBS - sodium fluorosilicate 6.90

CS 272995 Bl

The melted glass is fritted in water and after drying it is ground with an addition of 0.15% by weight of methyl hydrogen siloxane containing 10% by weight of cobalt naphthenate to a particle size distribution of the powder such that the weight fraction of particles larger than 63µm is 10-15%. After heat treatment of the powder by heating to 160 ° C for 20 min. and after cooling, it was applied in an electric field and the formed layer was baked at 800 ° C.

Example 2

The enamel frit for the preparation of white titanium powdered enamel is melted at 1250 ° C from the following percentages by weight.

ai ₂ o ₃ SiO ₂ - alumina - silicon dioxide 3.60 42.40 ^B 3 ° 3 - boron trioxide 13.20 Nb ₂ O - sodium oxide 7.10 KGO - potassium oxide 5.50 Li ₂ 0 - lithium oxide 0.50 MgO - magnesium oxide 1.00 Tioga - titanium dioxide 16.70 ^P 2 ° 5 - phosphorus pentoxide 2.00 NaP - sodium fluoride 2.00 THE DOG - sodium fluorosilicate 5.90

The further procedure is identical to Example no. First

Titanium white powder enamel of the invention may be administered ¹ to ² Bua metal substrate directly or on a metal substrate provided with a layer of enamel deposited on the base field and the non-fired elektriekom respectively. for baked base enamel based on silica, phosphorus, aluminum, boron, titanium, alkali metal and rare earth oxides, sodium fluorosilicate and sodium fluoride.

Claims (2)

OBJECT OF THE INVENTION White titanium powder enamel for dry application in an electric field to a metal substrate, characterized in that it contains 3.1 to 6.00% by weight of alumina, 38 to 46% of silica, 12 to 18% of boron oxide, 6 to 9% sodium oxide, 4 to 8% potassium oxide, 0.1 to 1% lithium oxide, 0.8 to 1.6% magnesium oxide, 16 to 20% titanium dioxide, 1.5 to 3% phosphorus pentoxide, up to 2% sodium fluoride and up to 7.5% sodium fluorosilicate. 2. White titanium powder enamel according to claim 1, characterized in that said mixture is ground with an addition of 0.10 to 0.30% by weight of a silicone oil containing 5 to 15% catalyst for a particle size distribution in which particles above 63 .mu.m they comprise from 8 to 15% by weight.