Study On Preparation Process Of Aqueous Dimethyl Silicone Oil Lotion Mold Release

Since the 21 st century,with the development of metal casting industry and plastic manufacturing industry,industrial production has become increasingly demanding in terms of quantity and quality of release agents.Water-based silicone emulsion mold release agents have the advantages of high temperature resistance,low surface energy,good mold release effect as well as organic solvent free,non-toxic and environmental friendly making them widely used and become the main development direction of mold release agents for hot molds.In this paper,three emulsifier systems,namely monoglyceride emulsification system,Span80 emulsification system and polyoxyethylene ether emulsification system,were used to prepare silicone emulsions with stable performance as the target.The complex nonionic emulsifiers required for the emulsification of silicone oil were prepared by selecting suitable nonionic surfactants and co-emulsifiers by HLB method(hydrophilic-lipophilic balance method)and homogeneous design method and optimizing their ratios.The silicone oil emulsification was mainly performed using the trans-phase emulsification method,and a high-speed shear homogenizer was used appropriately to prepare stable dimethyl silicone oil emulsions.The effects of process parameters such as emulsifier content,emulsifier ratio,emulsification time,stirrer speed and emulsification temperature on the trans-phase and properties of the emulsions were also investigated to determine the optimal process conditions for the preparation of silicone oil emulsions.The results showed that all three methods could prepare stable silicone oil emulsions.The preparation process of monoglyceride emulsion system requires heating and homogenizer shear emulsification,and the operation is relatively more complicated,and the maximum silicone oil content is 30%;Span 80 emulsion system does not require homogenizer shear emulsification,but the emulsification time increases,and the maximum silicone oil content in the emulsion is 30%;The emulsification temperature of the polyoxyethylene ether emulsification system is room temperature,without heating and homogenizer emulsification,emulsification time is longer,but the maximum silicone oil content can reach 40%,and the emulsion particle size is smaller than the other two emulsifier system.The particle size,storage stability,and emulsion dispersion of the silicone oil emulsions from the three emulsification systems were tested,and the results showed that the silicone oil emulsions prepared by the polyoxyethylene ether emulsification system had the smallest particle size and the most stable emulsions.Finally,the polyoxyethylene ether emulsion system was selected,and a 20 kg silicone oil emulsion scale-up experiment was conducted,and the relevant process parameters were adjusted.The produced products were handed over to the customer for hot demoulding effect test,and compared with the products on sale in the market for demoulding.The silicone oil emulsion prepared by polyoxyethylene ether emulsification system has the characteristics of more times of demoulding,smooth surface of sand core moulding,and can be used for structural precision sand core casting,etc.The demoulding effect is obviously better than the market products,and the produced silicone oil emulsion has been promoted and applied in many casting enterprises.