Q: What coupling agent is used to treat the hydroxyl groups on the surface of white carbon black?
Answer:White carbon black is the general term of white powder X-ray amorphous silicic acid and silicate products, mainly referring to precipitated silica, fumed silica and ultra-fine silica gel, as well as powder synthetic aluminum silicate and calcium silicate. White carbon black is a porous substance, which can be composed of SiO2&Middot; nH2O represents, where nH2O exists in the form of surface hydroxyl groups. Soluble in caustic soda and hydrofluoric acid, insoluble in water, solvents, and acids (except hydrofluoric acid). Resistant to high temperatures, non flammable, odorless, tasteless, and has good electrical insulation properties. There are three types in total, namely isolated hydroxyl, adjacent hydroxyl, and double hydroxyl. The relationship between the content of different hydroxyl groups and the production process is roughly as follows: the surface hydroxyl groups of newly produced gas-phase white carbon black are mainly isolated hydroxyl groups. With the extension of time, the adsorbed water on the surface increases, and the surface silicon oxygen groups of gas-phase white carbon black can be converted into silicon hydroxyl groups (once silicon hydroxyl groups are formed, they form adjacent hydroxyl groups with adjacent hydroxyl groups that were originally isolated). Therefore, the number of isolated hydroxyl groups will decrease, while the number of adjacent hydroxyl groups will increase.
Modified gas-phase white carbon black requires the use of one silane coupling agent Tetramethyldiethyldisilazane is a colorless and transparent liquid, non-toxic, and soluble in most organic solvents such as ethyl acetate, toluene, and cyclohexane. CAS number: 7691-02-3, mainly used for surface treatment of gas-phase white carbon black in liquid silicone rubber products. The recommended addition amount is 2% -5%. The treated white carbon black changes from hydrophilic to hydrophobic and can better affinity with raw rubber.
Tetramethyldiethyldisilazane also has other uses, such as being used as a synthetic intermediate for medical and other chemicals; Can be used as a coating additive; Can be used for the manufacturing of silicone rubber, silicone colloid, and vinyl silicone resin; Can be used as a ceramic surface treatment agent.
matters needing attentionWhen storing, do not come into contact with open flames. Keep it ventilated and dry, prevent sunlight exposure, and store at a temperature of -45 ° C—40； During transportation, collisions should be avoided and protected from rain and sun; Storage and transportation of dangerous goods.
