SU1296275A1 - All-purpose antistick paste for producing aqueous quick-setting coating - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to a foundry, in particular, to the compositions of nonstick coatings of casting molds and cores for castings from iron, steel and non-ferrous metals and alloys. The purpose of the invention is to improve the quality of the coating by increasing its strength and mediation stability. The goal is achieved by the fact that the paste additionally contains phenol-formaldehyde resin, and, as an organic binder, glycerol tar with the following ratio of ingredients, wt.%: Refractory filler 35-90; technical lignosulfonates 2-10; glycerin tar 2--10; phenol formaldehyde resin 1-5; the solvent is the rest. From a paste of this composition, which contains binders that are soluble in water and organic solvents, both water-based and quick-drying coatings are prepared, which are characterized by high heat resistance due to the fact that at high temperatures of the metal poured into the metal form the coating releases shiny carbon. , forming a coke frame in the coating layer, as well as good hiding power due to the fact that the coating has high sedimentation stability. 2 tab. (C (L from go with O5 th SP

Description

The invention relates to foundry, in particular, to the compositions of nongonigong coatings of casting molds and cores for castings of iron, steel and non-ferrous metals and alloys.

The purpose of the invention is to improve the quality of the coating by increasing its strength and sedimentation stability.

Glycerin tar (VAT residue from the purification of raw glycerol by distillation) consists of polyglycerols, glycerol acids and glycerol residues. It dissolves well in water, alcohol and acetone, it is frost-resistant when mixed with technical lignosulfonates, phenol-formaldehyde resin and oils of 10

to obtain a coating, it is diluted to the required viscosity and density with water or organic solvents. The paste does not brood, does not lose its properties during long-term storage. At high temperatures under the conditions of the casting mold, the coating emits shiny carbon, forms a coke skeleton in a layer}} {digging, which ensures an increase in the heat resistance of the mold and the production of castings without burns.

The coating is made in a pan mixer (runners) by mixing the dry components for 3-5 minutes, then technical lignosulfonates are added and mixed for another 5 minutes.

develops a uniform sticky liquid mass. 15 Thereafter, glycerol tar is introduced and

20

Phenol-formaldehyde resin is an antiseptic, it ensures the safety of the paste, preventing microbiological decomposition. At the same time, it has thermo-reactive properties, high adhesiveness and ability to wet mineral fillers, which contributes to increasing the strength of the dried coating layer.

water Stir the whole mass for 30-35 minutes.

Bentonite can be introduced in the form of a powder or aqueous suspension (1:10). If bentonite is introduced in the form of dry sheath, then the paste must be aged (for swelling of bentonite) for at least an hour before diluting the paint.

Technical lignosulfonates (for example, sulphite-yeast mash) are surfactants that improve the wetting of the dry components of the coating when mixed.

The bentonite molding clay, being in a water paste in a swollen state, provides high sedimentation stability of the quick-drying coating on an organic solvent.

The combination of glycerol tar and phenol-formaldehyde resin provides anti-burn coating with good sedimentation resistance. This is due to the fact that glycerin tar, being a mixture of glycerin and glycerin acids, has the properties of surfactants, which improve the wettability of the mineral filler particles, which leads to a decrease in the friction forces between them and the dispersion medium (in this case - water) and as a result, the rate of deposition of the filler increases under the influence of gravity.

When an aqueous solution of glycerin tar is contacted with particles of a phenol-formaldehyde resin, the solution thickens due to the redistribution of the most chemically active hydroxyl groups of OH, of which there are 3 groups in the glycerol molecule and 1 in phenol-formaldehyde resin.

Due to this, the smallest particles of phenol-formaldehyde resin are dissolved and the filler particles are covered with this viscous solution.

Aqueous paste, in which glycerin tar is used as a binder together with phenol-formaldehyde resin

to obtain a coating, it is diluted to the required viscosity and density with water or organic solvents. The paste does not ferment, does not lose its properties during long-term storage. At high temperatures under the conditions of the casting mold, the coating emits shiny carbon, forms a coke skeleton in a layer}} {digging, which ensures an increase in the heat resistance of the mold and the production of castings without burns.

The coating is made in a pan mixer (runners) by mixing the dry components for 3-5 minutes, then technical lignosulfonates are added and mixed for another 5 minutes.

5 Thereafter, glycerin tar is introduced and

0

five

0

five ,.

50

five

water Stir the whole mass for 30-35 minutes.

Bentonite can be introduced in the form of a powder or aqueous suspension (1:10). If bentonite is introduced in the form of dry sheath, the paste must be aged (to swell bentonite) for at least an hour before diluting the paint.

Glycerin tar should be applied in the form of an aqueous solution with a density of 1.24-1.3 g / cm with a pH of 7-8. The phenol formaldehyde resin is introduced as a powder or as a liquid solution.

Yves of said paste are prepared with a water nonstick coating or a quick drying nonstick coating if the paste is diluted with alcohol or acetone. As a refractory filler, graphite, electrocorundum, and other materials in their combination can be used.

Table 1 shows the compositions of pastes.

In tab. 2 - properties of diluted coatings obtained from these pastes.

Compounds 2-6, 8-10 correspond to the invention.

From the data table. 2 it follows that the water and quick-drying nonstick coatings prepared from the proposed pastes have higher strength and sedimentation stability.

The optimal content of glycerin tar in universal pastes is 2-10 wt.%, Phenol-formaldehyde resin is 1-5 May. %

The technical and economic advantages of the proposed universal paste in comparison with the known paste consist in increasing the heat resistance of the coating provided by the increase in strength and sedimentation stability of coatings, which contributes to obtaining castings without burns. The use of glycerin tar in the paste, which is a by-product of the processing of glycerin, contributes to

reduce environmental pollution.

Claims (1)

Invention Formula A universal anti-stick paste for the preparation of an aqueous and quick-drying coating, mainly for casting molds and cores, including a refractory filler, bentonite molding clay, technical lignosulfonates, an organic binder and a solvent, so as to improve the quality of the coating due to - degrading its strength and sedimentation stability, the paste additionally holds the phenol-formaldehyde resin, the quality of the organic binder is cerinous tar at the following ratio Gredient, wt.%: Refractory filler35-90 Clay molding bentonite 2.5-5 Technical lignosulfonates 2-10 Glycerin tar 2-10 Phenol-formaldehyde resin1-5 Solvent Remaining Table 1 table 2