TYPES AND CHARACTERISTICS OF ORGANOSILICON DEMOULDING AGENTS (IV)


3. Typical products of organosilicon release agent


3.1 Demoulding Agent for Rubber Tire Processing


The emulsion type silicone release agent used for rubber tire forming process uses methyl silicone oil or benzyl silicone oil, hydroxyl terminated silicone oil and a small amount of silicone resin with active reactive groups (silicon hydroxyl) as the main polymer, with proper alkoxy silane crosslinking agent and organotin carboxylate catalyst, and additional wetting agent and sterilization. The emulsion type silicone release agent prepared by adding water and emulsified agent has stable storage, good demoulding effect and long service life. It can be used in the forming of pneumatic or semi-pneumatic tires. The friction force of the outer surface of the tire peeled off from the steel film surface is low, and the separation lubricity between the inner surface of the tire and the pneumatic balloon is good.


Organosilicon polymer was synthesized from high boiling and low boiling substances fractionated by methyl chlorosilane monomers. It can also be used to produce release agent for rubber and plastics products.


3.2 aerosol silicone release agent


Aerosol-type silicone release agents mostly use silicone oil with proper viscosity as the main organosilicon polymer, with wetting agent, ejector and other components, sealed in a metal tank with spraying device. When used, the injection button is pressed, and the release agent is sprayed into the working surface of the mould in a micro-droplet shape. After evaporation of the ejector, a release agent is formed. Working film. The aerosol silicone demoulding agent is easy to use and is mainly used in the moulding of small size fine rubber plastic parts and plastic packaging of electronic components.


The application of silicone oil with different viscosities in aerosol silicone release agent can improve the release effect and increase the effective release times of each spray film. If water-soluble polyether modified silicone oil is used as the main component of release agent, the silicone release agent prepared does not affect the subsequent bonding and Finishing Properties of release products.


3.3 High Temperature Resistant Silicone Demoulding Agent for Aramid Fabric Mould


The thermal resistance of aramid fiber is up to 350 C, and its mechanical strength is high. The hot-pressing of wood chips fiberboard with aramid cloth as a die has high production efficiency, which is the current preferred advanced forming process of fiberboard. However, the bonding resistance of aramid fabric is not good. In order to prevent the bonding between the bonding agent and the aramid fabric die, a variety of release agents are not suitable. Most release agents do not match the high temperature resistance of aramid fabric. Although the heat resistance of the stripping agent with ordinary silicone resin base material is acceptable, the common silicone resin cured paint film can not play the role of stripping isolation.


The highly curable active methyl phenyl silicone resin developed by the author with special synthetic technology not only has the high heat resistance of the usual methyl phenyl silicone resin, but also has the outstanding advantages of high curing activity, strong adhesion between the cured film and the base material, and never returning adhesion of the cured film. The high curing active methyl phenyl silicone resin was coated on the aramid fabric. After heat curing, the silicone resin coating was firmly attached to the aramid fabric. After long-term operation under high temperature moulding, the excellent demoulding performance was maintained.


3.4 High Temperature Resistant Non-migrating Silicone Demoulding Agent for Space Engineering


The forming temperature of high performance fiber reinforced composites used in aerospace engineering is high, and the forming products need to maintain reliable bonding performance. The requirement of release agent for this kind of composite material forming process is very strict: besides the requirement of high forming precision and low stripping force, the working temperature of release agent is required to reach 180 C or even 400 C for individual workpiece. At the same time, the component of release agent should not be migrated to the workpiece to avoid influence. Continuous bonding processing. A demoulding agent was prepared by using special composite silicone resin as basic polymer, high temperature resistant wetting agent and composite solvent. The coating of the release agent has good leveling property, and the film can be used repeatedly after being cured at 150 C to maintain the reliable release performance of high temperature and non-migration. Because of its high efficiency and reliability, this demoulding agent is widely used in the processing of various aerospace engineering composite materials.


3.5 Anti-sticking and Isolating Agent for High Efficiency Immersion Coating


When electronic components are impregnated with liquid resin such as epoxy resin, it is often difficult to remove the metal lead adhering to the liquid resin used in packaging. If mechanical scraping is used, not only the efficiency is low, but also the solderability of components will be affected by scratching the coating on the lead; for example, the common release agent is used in advance. Coating metal lead often results in the absence of impregnated packaging resin at the root of lead and the inability to mark components after packaging due to the migration of release agent. A high effective anti-stick and isolating agent for dipping coating was developed by using low surface energy organosilicon polymer and high cross-linking curing agent components. After curing, the electronic component is immersed in the liquid epoxy resin, which exceeds the lead area pre-coated by the separator. When the electronic component is raised from the bathing bath, the epoxy resin originally attached to the lead area of the pre-coated separator will automatically reverse gravity upward. Shrinkage, to achieve tight and full package of electronic components and lead completely free of resin, the electronic components made to maintain reliable solderability.


Silicone release agents include different forms and formulations, which are suitable for different types of materials and different processing technologies. Therefore, it is necessary to select the most suitable release agent according to the working temperature, peeling force and the requirements of subsequent surface coating and bonding.


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