Carbon black for coloring:
The pigment carbon black generally can color the plastic well, and the pigment carbon black can be selected according to the coloring property or the physicochemical property, and the selection of the coloring carbon black is basically determined by the blackness which must be achieved by the finished product. Very fine coloration of carbon black can be used to achieve particularly high coloration;
PE garbage bags, plastic bags, cable materials and other products only need medium-level blackness, and can use carbon black varieties with lower specific surface area and higher structure; small errors in carbon black weighing and compounding when plastic coloring , will lead to obvious chromatic aberration, therefore, it is better to use low-color carbon black with larger particle size and poor tinting strength, so the amount of carbon black can be slightly larger, the weighing error is relatively small, and the dispersion is better, the price Lower advantage.
For gray plastics, fine-grained pigment blacks tend to exhibit a brownish-grey gray, while coarse-grained pigmented carbon blacks produce a blue-phase gray. Compared with other organic pigments, carbon black has better performance in addition to dispersion. The scientific amount of carbon black can provide better antistatic or electrical conductivity. Carbon black is basically non-toxic, but it is easy to fly and pollute. Therefore, it is often used in the form of masterbatch for the plastics industry. It also improves the dispersion of carbon black in plastics while eliminating pollution. Carbon black is used as a pigment for plastics, and the usual dosage forms are powdery and granular. Granular carbon black is less flying, but it is difficult to disperse, so powdered carbon black is used in plastic coloring.
One of the uses of carbon black in the plastics industry is anti-ultraviolet aging. Because of its high absorbance, carbon black can effectively prevent photo-oxidative degradation of plastics from sunlight. Carbon black as an ultraviolet light stabilizer plays a role in plastics: converting light energy into heat energy; protecting the plastic surface from radiation of a certain wavelength; intercepting the atomic group to prevent aging, thereby preventing catalytic degradation. Ultraviolet rays are particularly harmful to polyolefins, and tests have shown that a perfect UV shielding effect can be achieved when the concentration of carbon black of a certain fineness is 2%.
The protective effect of carbon black on the UV aging of plastics depends on the particle size, structure and surface chemistry of the carbon black. When the particle size of carbon black is small, the absorption of light or shading ability is increased due to the increase in surface area, so the ultraviolet protection effect is enhanced, but the particle size is less than 20 nm, and the protective effect tends to the same level, because the particle size is too small, reverse The scattering is reduced, and the light that continues to move forward threatens the stability of the polymer.
The structure is relatively low, that is, when the aggregate size is small, the geometrical volume of the aggregate is small, which enhances the protection of the polymer, which is also the reason why the carbon black of the lower structure is darker. The surface of the carbon black has a large number of oxygen-containing groups, that is, when the volatile matter is high, the gene generated when the polymer is decomposed can be eliminated, and thus the protective effect is also enhanced.