Compound modified water glass binder and preparation method thereof

Abstract

The invention discloses a compound modified water glass binder and a preparation method thereof. The compound modified water glass binder comprises the following effective components in percentage by mass: 10-25 percent of modifying agents and 75-90 percent of water glass; the modifying agents are prepared by the following components in percentage by mass: 33.3-36.6 percent of water-soluble starch, 23.8-24.4 percent of dextrin, 2.43-4.76 percent of urea, 24.4-28.6 percent of sodium tripolyphosphate and 9.52-12.2 percent of borax. The method for preparing the compound modified water glass binder comprises the following steps of: 1, preparing water-soluble sodium polyacrylate resin water solution; 2, weighing raw materials and preparing the modifying agent used by the compound modified water glass binder; and 3, weighing the modifying agent and the water glass to prepare the compound modified water glass binder. By the binder, the addition amount of the water glass in moulding sand is reduced, and the poured moulding sand easily scatters, so that the regeneration rate and the recycling rate of the water glass sand are improved, and the binding capability is improved.

Description

technical field [0001] The invention belongs to the technical field of preparation of molding sand for casting and molding sand binder, in particular relates to a composite modified water glass binder, and also relates to a preparation method of the above binder. Background technique [0002] Water glass, also known as sodium silicate aqueous solution, is an inorganic casting binder. Due to its low price, no smoke and black pollution in the metal casting process, it is one of the sand binders widely used in the production of steel castings. . But the existing water glass binder due to Na 2 The content of O ions is high. After the liquid metal is poured, a large part of the molding sand and water glass are heated to above 800°C. At this time, the water glass will become liquid, which will strongly erode the quartz sand. After cooling, the water glass and the quartz sand The formation of extremely hard sand blocks leads to high residual strength of water glass sand, poor col...

AI Technical Summary

Problems solved by technology

But the existing water glass binder due to Na 2 The content of O ions is high. After the liquid metal is poured, a large part of the molding sand and water glass are heated to above 800°C. At this time, the water glass will become liquid, which will strongly erode the quartz sand. After cooling, the water glass and the quartz sand The formation of extremely hard sand blocks leads to high residual strength of water glass sand, poor collapsibility, that is, poor sand production, and difficulty in regeneration and reuse. These defects largely limit the application of water glass

[0003] From a chemical point of view, the main reason for the poor collapsibility of water glass sand is Na 2 The result of the action of O ions, that is, the water glass contains a large amount of Na 2 O ions, so that more sodium silicate remains after ventilation, and will polymerize into glassy sodium silicate at 200-300 ° C. It is as hard as a stone and makes the first residual strength peak rise; and it reaches high temperature at high temperature. After the melting point, the bonding film is in a liquid state, and the melting and erosion process of the molten water glass on the quartz sand begins. The higher the temperature, the greater the amount of quartz sand dissolved in the water glass, the greater the modulus, and the reconstituted water glass. It makes the water glass adhesive film thicker, and after cooling, the plates are connected together, which increases the residual strength and leads to poor collapsibility