1. Water glass sticky There are two reasons for the generation of bubbles in the cementing material:
1. Because the wax-based molding material (resin-based molding material) is hydrophobic, and the water glass (silica sol) is a hydrosol , the binder contains a large mass fraction of free water. When the module is immersed in the surface slurry of water glass binder, the wax mold is not stained with slurry and the slurry flows straight down. Only an extremely thin slurry is left on the wax mold. The slurry flows straight down and only The extremely thin slurry cannot bond the sand particles, and the sand particles are almost in direct contact with the wax pattern. It shows that the wetting angle between water glass binder and wax-based molding material is as high as 69°, so surfactant must be added to improve the coating performance of the slurry.
2. When preparing water glass adhesive slurry, most manufacturers use homemade mixers. The main shaft of the motor passes through the pulley to stir the paint in high-speed rotation mode, causing a large amount of air to be involved in the slurry, causing Surfactant foaming.
2. n-octanol can improve the coating properties of slurry:
n-octanol (octaol): colorless liquid. Has a strong aromatic smell. Density 0.83. Refractive index 1.430. Melting point -16℃. Boiling point 196℃. Not miscible with water, but miscible with ethanol, ether and chloroform. Used in making flavors and cosmetics, and as solvents, antifoaming agents, plasticizers, antifreezes, lubricating oil additives, etc. It is a by-product of making lauric acid from coconut oil. It can also be obtained by catalytically controlled polymerization of ethylene and then hydrolysis and separation.
The purpose of adding n-octanol is to remove the foaming produced during the stirring process of the slurry, which is the so-called defoaming agent.
n-Octanol has another characteristic. It can reduce the surface tension of water glass adhesive slurry and improve the coating properties of surface layer slurry. This has been ignored for a long time. If JFC is not added or added in trace amounts, the production of foaming can be suppressed from the source, or the amount of foaming can be reduced to a minimum, so that n-octanol can defoaming and at the same time highlight the coating performance of n-octanol-enhanced slurry. The role of
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