Paint problems with blending

Problems with Blending. The principle of this approach to optimizing paint rheology is that two paints with the same Stormer viscosity will produce blends with the same Stormer viscosity. In practice, this result does not always occur. For example, a 50/50 HEUR/organoclay-thickened paint made from base paints at 100 KU each may have a Stormer viscosity of only 90 KU. This result often occurs when one of the base paints is very thixotropic. Also, a paint blend may have poorer flow and leveling than either of the base paints. Poor flow indicates that some flocculation may occur during the blending process. 

Due to cost reduction needs of late, these blends have been substituted by reactor blends using stepwise propylene- and ethylene-propylene copolymerization techniques in the gas phase. Thus the rubber elastifier is introduced in a low-cost one-step process. Rubber contents as high as 50 percent can be provided. It was quickly seen that TPO produced by this manufacturing method gave more problems with paint adhesion than that seen in traditional PP-EPDM compounds. 

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