Blooming, color migration

A monofunctional amine synergist which, when used in conjunction with a photosensitizer such as benzophenone, promotes rapid curing luider UV light. Additional benefits include reduced odors both at press side and in the cured film, reduced blooming or migration, and color fading of selective pigments such as reflex blue and rbodamine red. 

Pigment concentration is not the only system-dependent migration determinant the entire composition of the colored medium plays a role. The tendency of plasticized PVC to promote blooming, for instance, depends on a series of para-... 

Strong migration tendencies practically exclude monoazo yellow and orange pigments from being used for the mass coloration of plastics they bleed and bloom considerably in most polymer systems. Again, Pigment Yellow 97 is an exception... 

Three properties that contribute the most to migration are (1) incompatibility with the resin, (2) low melt point, and (3) low molecular weight. Examples of noncolorant additives that are prone to migrate are (1) lubricants/dispersants such as metal stearates and bis-stearamides, (2) mold release and slip agents, and (3) antistatic agents. All of these ingredients serve useful purposes in color formulations. If you exceed their solubility limit in the end-use resin, however, you risk blooming and its consequences. 

The following factors, in combination with the plastic to be colored, are decisive in determining the suitability of a colorant for a particular application namre, thermal load capacity (level and duration), light fastness, weather resistance, migration tendency (solvent and cmitact bleeding, blooming), plateout (deposits on metal surfaces in contact with melt) and influence on flow behavior [45]. 

Hitco calcium stearates can also reduce the possibility of "bloom," and the resultant color distortion, because they resist migration to the surface of finished products during storage. 

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