In PVC rigid plastics, adding calcium carbonate can reduce production costs and improve the mechanical properties of PVC products. However, calcium carbonate has a relatively large specific surface area, high surface energy, and is very easy to agglomerate. As a result, it is impossible to exert the reinforcing properties of nano-calcium carbonate. It is too wasteful to only act as a filler. Calcium is modified on the surface to reduce the surface energy between nano-calcium and achieve the effect of uniform dispersion.
How powder modifiers modify calcium carbonate?
The surface modification of calcium carbonate is to adsorb or react the powder modifier on the surface of calcium carbonate by physical or chemical methods to form a coating film to reduce the molecular force between the powders, uniformly disperse in the PVC system, and strengthen the polymer and the The bonding force between fillers can effectively improve the strength of various indicators of PVC products.
The modified nano-calcium carbonate can effectively solve the problem of agglomeration, and some modifiers can also reduce the oil absorption value and greatly reduce the production cost.
Manufacturers of nano-calcium use a large number of stearic acid, sodium polyacrylate, coupling agent and other products, which can quickly disperse and greatly enhance the activity of calcium carbonate, but it may not be applicable when supplying PVC pipe manufacturers.
Mainly reflected in the following aspects:
1. In the PVC production process, the higher the degree of activation of nano calcium carbonate, the more throwing the powder, the lower the surface dry density, and the lowering of the material is not good. At the same time, under the condition of high temperature of the internal mixer, the modifier is easy to volatilize, resulting in The nano-calcium carbonate is again agglomerated and the exact density of the product is not good.
2. Using such additives, in the downstream production process, the fumes are large and difficult to be discharged, and the odor is also relatively large, which seriously affects the production environment and endangers human health.
The water-based powder modifier is used to improve the dispersion of nano-calcium carbonate and the filling amount of nano-calcium through effective coating modification during the preparation of nano-calcium carbonate. , and high temperature resistance when entering the mixer, the nano calcium carbonate will not re-agglomerate due to volatilization due to high temperature, and there is no pungent smell and little smoke, and the exhaust fan in the production workshop is easy to discharge.
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