Basic knowledge about pigments
Colored substance that has an affinity to the substrate to which it is being applied. Synthetic colorants Characteristic of dyestuff is know through it’s brilliant color at low concentration and transparency of the colorant. However due to it’s solubility in the medium, it could not be used in some thermoplastic polymers such as polyethylene, polypropylene.
Inorganic pigments are crystals of natural or synthetic metal oxides, sulfide or other salts used as a coloring agent for plastics, paints and inks. This structure is extremely stable, therefore inorganic pigments have excellent properties such as light fastness, weathering fastness, heat stability, migration,..etc. Typical inorganic pigments used in plastics such as TiO 2, Fe 2 O3, ZnS, PbCrO 4 , ..etc
are chemical synthetic with carbon based molecules manufacture chemicals, usually under intense heat and pressure. They are often most saturated and strongest tinting colorants. However their properties such as light fastness, heat stability could change dramatically depending on the particle size, crystal form or the type of substrate used. Typical organic pigments used in plastics such as Phtalocyanine pigments, Diarylide pigments, Chinacridone pigments Azo pigment
Color shade acceptance
Standard procedure for preparing the comparison samples
Color shade comparison method
Heat Stability of the Masterbatch
Heat resistance test of color based DIN 53772
Light fastness of the Masterbatch
Light fastness test in accordance to DIN 53388 Test result will be compared against the blue scale
Migration test in accordance to DIN 54002
Warpage of the final product
Cause of warpage of the final product
Slow temperature set down of the final product, causing uneven temperature gradient throughout the molded body.
Warpage phenomena is also caused by some organic pigments, mold design, processing condition and processing machine.
Rheology of the Masterbatch
The melt flow index or MFI is a measure of the ease of flow of the melt of a thermoplastic polymer. It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.
The MFI will be measured in accordance to ASTM D123 8
Extrusion Plastometer and testing condition in accordance to ASTM D1238
Dispersion and Distribution of the Masterbatch
Dispersion of Pigment
Pigment dispersion is necessary so to obtain optimum tinctorial strength, cleanliness of shade and good gloss on the final product. Poor dispersion of the pigment or pigment agglomerates could be notice as dark dots on the surface of the final product
Distribution of Pigment
Pigment distribution is to be understood as homogeneous dissemination of the pigment particles in the final product. Uneven distribution of the pigment could be seen as color streaks or flow lines on the surface of the final product.
High Volume Products