Full Analysis of Application of Silicone in Demoulding Field


Basic working principle of release agent


Rubber and plastic products are processed in moulds. Rubber and plastic materials contact with the surface of moulds. There may be some friction resistance when rubber and plastic products peel off from moulds due to micro defects such as concave and convex working surfaces of moulds. In the process of injection or extrusion of rubber and plastics, negative pressure is often formed between rubber and plastics materials and moulds, or the bonding between them is caused by physical adsorption or chemical bonding. As a result, it is difficult to peel the rubber and plastic products from the mould after forming. In order to weaken the adsorption or adhesion between products and molds, a demoulding agent is often used as an additive to form an effective separation membrane. The release agent is a surface coating layer used on two surfaces that are easy to adhere to each other, resulting in an isolation between the adhesive and the sticky material, resulting in the weakening of the peel force and the demoulding of the product. It's easier and more convenient.


Types and applications of release agents


Generalized release agents include many types, which are used in chemical industry, metallurgy, building materials and other fields. This paper is limited to the release agent in chemical industry, mainly discussing the external release agent in the forming process of rubber, plastics and other materials.


There are many kinds of basic materials which can be used as demoulding agents. The commonly used demoulding agents are inorganic, organic and polymer. Inorganic release agents are commonly used in graphite powder, talcum powder, mica powder, molybdenum disulfide and other powders; commonly used organic release agents are fatty acids, fatty acid soaps, waxes, ethylene glycol, etc., which have both the role of lubricants; polymer release agents are mainly polyvinyl alcohol, cellulose acetate, organic fluorine. Polymers and organosilicon polymers, among which organosilicon polymer is the most suitable release agent.


The formulation of release agent can be divided into two types: solid and liquid. Solid morphology is the application of fine powder materials. Because of the inconvenience and possible transfer of powder materials to the surface of rubber and plastic products, it is seldom used in the processing of rubber and plastic products. The most commonly used release agents are mostly liquid, some of which use liquid bulk polymers, and other solutions, emulsions, and paste made of effective agents, such as solvents, emulsifiers, fillers, etc., and aerosols such as liquid propellants. Some of the release agents coated on the mould exist in the form of liquid film, and some solidify into solid film.


From Silicone Forum