Silicone, scientific name is generally called siloxane and polysiloxane. The silicone powder used in the market is usually made of organosilicon and silicon dioxide with a higher polymer content, that is, siloxane is dispersed in silicon dioxide, and silicone with a lower polymer content is usually liquid, which we usually call silicone oil. But if the molecular weight is large enough, it can be made into a flaky solid.
Generally speaking, silicone powder is distinguished according to the amount of siloxane content. If the siloxane content in your silicone powder is 40%, that is to say, the silicone powder should be 40% siloxane (silicone oil) + 60% silicon dioxide and other additives (such as coupling agents, etc.). If the silicone content is high, the shear is weak and not easy to disperse, and it is made into a masterbatch first, because the intermolecular force of siloxane is strong, it is not easy to disperse evenly by physical methods, and strong shear is required to complete it. The higher the siloxane content in the silicone powder, the greater the viscosity of the material, and the more difficult it is to disperse when used in plastics. When the siloxane content and molecular weight are high, it can be used as a wear-resistant agent, but it is used in the system.
The so-called silicone masterbatch is diluted silicone (usually siloxane + silica), and then 50%-30% of the carrier and other additives are used. The carrier is generally polyolefin, which can be directly used as an inorganic filler to add a wetting agent. Silicone oil (low molecular weight siloxane) is rarely used directly in the general modification industry due to its dispersibility defects. If silicone oil is used directly, it is necessary to ensure that it is fully dispersed to achieve the desired effect. It is currently widely used in elastomer modification (such as SBS, SEBS), on the one hand, it can change its wear resistance, and on the other hand, it can adjust its hardness. This process is usually called oil filling. The products produced by this method have great limitations in use and are easy to precipitate, which is usually called oiling.
The difference between silicone powder and coupling agent: Coupling agent generally consists of two parts, one part is an inorganic-philic group that can work with inorganic fillers or reinforcements; the other part is an organic-philic group that can work with synthetic resins. A plastic additive, also known as a surface modifier, is a plastic additive that improves the interface performance between synthetic resins and inorganic fillers or reinforcements. Silicone powder contains inorganic components, which is what we call silicon (here refers to silicon or silicate, that is, silicon in silicone powder and silicate in glass fiber or inorganic filler, and fillers in polymers are almost all silicates). It is wrapped in a nucleation structure by a polymer material (polysiloxane), and the interaction between its molecules is stronger than that of polymers and inorganic substances. The other end is a combination of polymers and alkanes, which plays a role in connection and startup in the interface layer. Many types of coupling agents are silanes, that is, they use the principle that the interaction between silicon molecules is stronger. Therefore, in some ways, coupling agents are a low-end product compared to silicone powder.
Different from TPFE (polytetrafluoroethylene) products. In terms of lubrication, the application of silicone powder in non-fluoroplastics can almost completely replace TPFE, while TPFE is better than silicone powder in fluoroplastics.
Unlike TAF, some manufacturers are promoting TAF (EBS or some wax + TPFE) in terms of preventing glass fiber exposure and improving scratch resistance. EBS or other low-molecular waxes have poor performance in high temperature resistance and generally degrade above 100 degrees, so they are easy to degrade and precipitate at high temperatures, affecting the surface effect. On the other hand, the effect of improving gloss is time-limited, that is, the product is good when it is printed, but it will fail after a period of time, resulting in poor surface effect and a large number of defective products. Then, silicone powder is something that other lubricants do not have, which can improve the penetration effect between resin and inorganic matter and increase the affinity of its surface. Silicone powder
is different from EBS and other waxes. EBS and some waxes have very small molecular weights, and are better than silicone powder for simple lubrication, but their temperature resistance is much worse than silicone powder, and they are not suitable for lubrication with EBS in acidic systems. In addition to lubrication, the best solution for silicone powder is to improve the interfacial compatibility of inorganic minerals and organic matter, which can play a role in wetting, while EBS has little effect on the lubrication of inorganic and organic matter.
Features and functions
Silicone plastic additives are made of ultra-high molecular weight polysiloxane and appear as white particles or powder. Mainly used as plastic processing additives, it overcomes the troubles and performance deficiencies of traditional dimethyl silicone oil processing. Silicone additives are safe to use, easy to mix, stable in performance, and easy to disperse in resins. They have the following functions and characteristics:
● Improve the fluidity and demolding performance of plastic processing. Reduce torque, reduce equipment wear, easy to fill the mold, and reduce product defective rate;
● Reduce friction coefficient, improve smoothness, improve surface gloss, enhance the silky touch of the surface, and improve scratch resistance;
● Improve flame retardant properties, reduce smoke density, and improve the impact strength and surface gloss of flame retardant materials;
● Good stability and good non-migration .
