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What are the surface modifications of calcined kaolin

time:2021/5/19 10:09:45    Views:

The surface modification of calcined kaolin is based on the needs of polymer products, such as the change of the original physical properties of the surface, it is the use of surface chemical principles, such as coupling agent on the surface of kaolin particles adsorption or chemical reaction. The structures of the two chemical groups were characterized by coupling agents.


Some groups react with hydroxyl groups on the surface of calcined kaolin powder to form strong bonds. Other groups have chemical reaction or physical entanglement with the organic polymer material, so as to change the surface properties of calcined kaolin and achieve the intention of surface modification.


Appearance modifier: modified kaolin is used as surface modifier of organic polymer products and is commonly used as coupling agent. The main coupling agents are silane, titanate and aluminate. Calcined kaolin surface modifier is generally used as surface modifier, with silane coupling agent as the main agent, and can be mixed with other coupling agents and other additives.


Silane coupling agent is an organosilicone compound, which is RSixn. Where: R is an organic group that cannot be hydrolyzed organic polymer material, and Xn indicates the hydrolyzed alkoxy group. Calcined kaolin surface modification, alkoxy silane coupling agent molecules, first hydrolyze the active silanol group composition, and then react with hydroxyl groups, forming a hydrogen bonding kaolin surface, concentrated into a covalent bond.


Due to hydrogen bond and covalent bond is greater than the interface reaction, van der Waals force between silane molecules silanol condensation, set the reticular structure in membrane formation, covering the kaolin particles appearance, and let the cat out of the no and organic polymer hydrolysis reaction of organic functional groups, the reactive group with organic polymer resin or physical wounds, Calcined kaolin and organic polymer binder add crosslinking bonds between the bridge, forming a strong chemical bond, that is to achieve the effects of surface modification of kaolin.


In recent years, the types of coupling agents are complicated, and the selection of surface modifier is the key to surface modification of kaolin. Different silane coupling agents and other auxiliaries have different methods, methods, and scales. Therefore, different coupling agents and auxiliaries should be selected according to the technical requirements of different organic polymer substrates and different occupations. For products with special requirements, two or more synergism coupling agents and auxiliaries should be selected, and compound surface modification of calcined kaolin should be carried out with compound surface modification agent. In addition, two or more coupling agents and auxiliaries can be added in use according to the technical requirements.


The amount of modifier can be calculated according to the amount of modification, surface volume and minimum covering area of calcined kaolin. The average experience is 013~112%.


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