NO118761B - - Google Patents

Description

Method for the production of swellable acid-resistant water glass putty.

In the acid building technique used for

plate linings of appliances, which are exposed

for the stresses of heat and pressure, primarily mortars that have a specific

swelling ability. By the extension that it

acid-resistant sheet lining or the device casing gets under the operating stresses,

especially from heat and pressure, the acid-resistant mortar, due to its swelling ability, more or less quickly applies a pre-stress to the plate lining in relation to the device casing.

In the case of the water glass putty used in

large scale in the acid building technique,

has so far been difficult to produce

swellable putty which was also permanent

against all practically occurring acids.

It was now found that one on a simple

way by adding at least one metal compound of cyanamide can induce or regulate the swelling of water glass putty.

These metal compounds, where the hydrogen atoms in the cyanamide have been replaced by metals, can be mixed with any type of water glass putty without any difficulty, and then to

the finished putty or, what for the most part

is more appropriate, for the putty meal or the glass of water. By impact of

heat and especially of hot liquids find

a turnover of the cyanamide then takes place

with the alkali silicates, whereby at the same time

hardening and swelling can be induced

in the water glass mortar. The hardened kitties

are acid-resistant and show a steady increase in volume, and have the above-mentioned effects on the acid-resistant plate linings.

As metal cyanamide compounds are suitable

especially compounds of divalent metals

themselves, e.g. of lead, manganese, zinc, cadmium and of alkaline earth metals such as magnesium, calcium, strontium and barium. These compounds are added to the water glass putties appropriately in an amount of 0.1-10 per cent calculated on the putty flour, corresponding to 0.25 to 20 per cent calculated on the water glass, but can in some cases also be added in larger or smaller amounts. By the term putty flour is meant the sum of all fixed components. For carrying out the invention, all known water glass putties are suitable which possibly also contain known hardening-acting additives alone or in mixtures, such as silicofluorides; acid amides such as formamide, oxamide, triacetamide, malonamide, esters such as glycolide, oxalic acid dimethyl ester, glycol diformate, glycerin triformate, acid anhydrides such as succinic anhydride, maleic anhydride, sulfochlorides such as p-toluene sulfochloride, etc. or metal oxides such as lead oxide or zinc oxide or known fillers, such as quartz, kaolin, diatomaceous earth, glass flour, porcelain flour, chamotte flour, stone flour, graphite including coke flour, silicon, silicon carbide etc. alone or in a mixture. Water glass putty that contains the alkali silicate as a powder in the putty flour is also suitable. Potash or soda water glasses or their mixtures can be used as water glasses.

It has already been described that lead cyanamide increases the swelling of underwater paints, which are made with products containing linseed oil. From this, however, it could not be concluded that cyanamides are suitable for regulating the swelling of water glass putty, all the more so because the hardening mechanism for color coating and water glass putty are completely different. The paints dry when the drying oils absorb oxygen in the air, while water glass putty, due to their completely different composition, hardens with the help of quite different reactions and both in their composition and in their physical structure are completely different from oil-containing ones paints.

Example 1: 100 parts by weight of a putty flour, which consists of

2 parts by weight formamide

0.5 » lead cyanamide 2.5 » diatomaceous earth 93 » quartz flour is mixed with 40-50 g of a soda water-glass solution with a molar ratio of SiO2 to NaaO = 2.65 and specific gravity 1.50: The putty hardens after 24 hours and gives when after eight days of storage in the air, boiled in calcium bisulphite liquor, a swelling of 0.6 per cent.

Example 2:

100 parts by weight of a putty flour consisting of 4 parts by weight calcium cyanamide 4 » kaolin and 92 » quartz flour

is mixed with 40-50 parts by weight of a potassium water glass solution with a molar ratio of SiO, to K20 = 1.88 and with a specific gravity of 1.42. The putty hardens by itself within 24 hours and gives, when it is boiled with 10 per cent sulfuric acid after eight days in the air, a swelling of 0.5 per cent. Instead of calcium cyanamide, barium cyanamide can also be used in smaller quantities. One can e.g. instead of 4 parts by weight of calcium cyanamide in the above putty, use a mixture of 3.5 parts by weight of calcium cyanamide and 0.5 parts by weight of barium cyanamide.

Claims (4)

1. Swellable water glass putty, characterized in that it contains at least one compound of cyanamide and a divalent metal. 2. Water glass putty according to claim 1, characterized in that it contains lead cyanamide. 3. Water glass putty according to claims 1 or 2, characterized in that it contains the metal compound of cyanamide in an amount of 0.1 to 10 percent calculated on the putty flour. 4. Water glass putty according to claims 1-3, characterized in that it also contains at least one hardener.