After aluminum hydroxide is added to the thermoplastic, the mechanical strength, especially the impact strength, will cause a decrease. Although the coupling agent is used to try to improve the strength, there is still no significant enhancement. Therefore, more than 95% of aluminum hydroxide is used in thermosetting plastics. The following details:
1. Application of unsaturated polyester
In glass fiber reinforced unsaturated polyester cast plastics (such as various high-voltage or low-voltage electrical switches), aluminum hydroxide is used as a filler to make plastic products flame retardant, smoke suppression and arc resistance. Aluminum hydroxide is also used for FRP layer pressing body, such as FRP tile, pipe, storage tank, etc., with good flame retardant effect.
2. Application of epoxy resin
In the epoxy resin, aluminum hydroxide has a specific flame retardant effect, the dosage is 40% ~ 60%, the oxygen index is twice as high as that of the unfilled epoxy resin, and at the same time? Enhances the arc resistance and arc tracking resistance. The aluminum hydroxide filled epoxy resin in the production of transformers, insulation equipment, switchgear and other aspects of the future is very bright.
3. Application of cross-linked polyethylene, B- acrylic cable
Among these high polymers, the flame retardancy is improved due to the filling of alumina and the excellent electrical insulation properties, so they are widely used.
4, Latex and adhesive applications
Latex rubber and carboxylated latex adhesives for carpet underlayment were the earliest markets for aluminum hydroxide, and consumption in this area is still leading today. It also replaces calcium carbonate and clay, which have little flame retardant ability, as a flame retardant filler in precoats, adhesives and foams. Generally, 100 parts of latex are added with 20-150 parts of aluminum hydroxide having a particle size of 3-20 μm, and 75-250 parts are added to the binder. It is estimated that latex precipitation is still the largest consumer of aluminum hydroxide in the future.
5. Application of PVC
The most studied area of aluminum hydroxide in thermoplasticity is polyvinyl chloride. Aluminum hydroxide can be substituted for calcium carbonate. Fillers are very easily incorporated into plasticized PVC. There are two ways to achieve high standards of flame retardancy: one is the use of aluminum hydroxide and phosphate ester plasticizer, and the other is the use of aluminum hydroxide and zinc borate, these formulations have been applied to PVC wire and cable materials. The addition of aluminum hydroxide in hard PVC is mainly for smoke suppression.
6. Application of polyethylene, polystyrene, ABS and other thermoplastics
Aluminum hydroxide has been used in flame retardant decorative calcium plastic board, and achieved good results. However, in these thermoplastics, the addition of aluminum hydroxide alone must reach more than 60% to show a certain degree of flame retardancy, and the impact strength of the plastic will be seriously affected. So far, the application of aluminum hydroxide in these thermoplastics is still a subject of continuous research.
7, Application of Synthetic Rubber
Aluminum hydroxide is a good flame retardant in synthetic rubber such as styrene-butadiene rubber and neoprene rubber. For example, the formula of flame retardant cable sheath is 100 parts of neoprene rubber, 70 parts of clay, 30 parts of calcium carbonate, 100 parts of aluminum hydroxide, 15 parts of zinc borate, 10 parts of antimony trioxide, 5 parts of zinc oxide, 4 parts of magnesium oxide, 5 parts of isocyanurate, Na-220.5 parts and 2 parts of stearic acid. The oxygen index of the obtained product is 50, and the vertical and horizontal combustion properties are excellent.