Aluminum Hydroxide Filler Seed Preparation And Surface Modification,

Alumina trihydrate (ATH) powder with small particle size has a favourable outlook because it has been used as filler more and more. On the other hand, seeded precipitation of the synthetic gibbsite from supersaturated sodium aluminate solution is the direct process of the ATH, therefore it will have a nice economical benefit that ATH filler is produced by the process of seeded precipitation. Compared with all other way of controlling the particle size, it is simple and well-handled and low-costed to use organic additive.Additive's effects on the particle size of the product(ATH powder) and production of ATH has been studied in this paper, base of this, it also discusses the additive how to effect the secondary nucleation and agglomeration and crystal growth. Conclusions have been drawn as follow:Additive influences the surface character of the ATH crystal, thereby it suppresses the secondary nucleation and most of the new crystals are plates; on one hand, it strengthens the agglomeration of the small particles, on the other hand, blocks the agglomeration of the large particles; additionally it also strongly inhibits the ATH crystals' growth when crystals is wearing more and more yet, as a result, the number of the large particles in the solution is gradual decreased then lost.The product particle size is well-controlled by using the additives, and the additive can prevent polarization of the particle distribution, consequently the product resembles the seed on the particle distribution. With respect of the mainly volume particles, it is slight that the additive influenced, and it is most remarkable that there is not the particles which is bigger than 74um in the product of the additive system, so we can get appropriate ATH powder filler from the process of seeded precipitation.Additionally, it has been studied about the surface modification ofthe ATH filler, results as follow: surface modification can improve the compatibility of unsaturated polyester (UP) and ATH filler's particles, and accordingly effectively decrease the viscosity of the mixture which is prepared by UP and ATH filler. It is slightly influence of the surface modification on the mold test pieces' brightness, but color tints is influenced with wide extents.