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The influence of organic pigments in the coloring of plastics


  The performance of pigments used in plastic coloring is not only determined by the chemical structure, but also related to the particle size and distribution of the pigment. The particle size of the pigment not only affects the shade and tinting strength of the pigment, but also affects its dispersibility, heat resistance, and light resistance in plastics. When the particle size of the pigment decreases, its transparency becomes better, the tinting strength increases, the brightness and gloss increase, while the heat resistance, light resistance and dispersibility decrease, so it is necessary to fully understand the influence of the properties of pigment particles on the coloring properties of plastics. In order to use each pigment well, to give full play to its maximum use value.
  Generally speaking, the pigment particle size is small, the specific surface area is large, the tinting strength is high, and the saturation is good; on the contrary, the particle size is large, the particle size is small, the tinting strength is low, and the saturation is poor. Pigment Yellow 183 has two varieties. Among them, the transparent variety has a small particle size and a yellowish tinting strength; while the covering variety has a large particle size, low tinting strength and a reddish light.
  The particle size of the pigment particles has a great influence on the dispersibility. Usually, the gap between the fine particle powder is smaller than the gap between the larger particles, so the wetting and penetration rate of the vehicle resin to the small particle powder pigment It is relatively slow, thus affecting the final dispersion effect of the pigment particles.
  Pigment varieties with the same chemical structure (Pigment Red 122), due to the use of different surface treatment processes, can obtain two products with different particle sizes. The filtration value of the filter screen with the aperture is tested, and two sets of data with very different results are obtained. Experiments show that pigments with larger particle size are relatively easy to be wetted and obtain better dispersion effect.
  As we all know, the properties of pigments are also related to the use concentration, which also requires close attention.