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Romantic spring, gold color Xiaobian share: the choice of pigment in the production of polypropylene masterbatch play a vital role

Polypropylene masterbatch mainly by the pigment, dispersant, polymer carrier composed of three parts. The choice of pigments in the production of polypropylene masterbatch plays a vital role in the following Xiaobian for everyone to focus on the relevant knowledge about the paint!

"Pigment"
Masterbatch production and polypropylene spinning on the requirements of the pigment must be the size of 1μm below the coarse fiber and the general size of plastic products can be 5 to 1 01μm. Can withstand all kinds of physical and chemical effects in the fiber forming process. The selected pigment must be stable at the spinning temperature without decomposition. While the pigment itself has no adverse effect on the polypropylene. This is mainly reflected in two aspects: First, the decomposition of pigment or pigment intermediates to generate free radicals, the polymer in the α-H off, the occurrence of free radical polymerization initiated; Second, the pigment contained in the metal or metal salt Thermal Oxidation of Polypropylene. In addition, the pigment must also have the basic properties such as weather resistance and wetting fastness (alkali treatment, water treatment), and easy dispersion.
According to the above requirements can be selected pigments are inorganic pigments and organic pigments two categories. General inorganic pigments are natural or synthetic metal oxides, sulfides and other salts. In the light resistance, weatherability, heat resistance and resistance to migration are better than organic pigments, but most of the inorganic pigment color strength is low, coarse particles, color is not bright enough, poor chemical resistance.

Suitable for polypropylene commonly used pigments are:

R Titanium dioxide, zinc white, cadmium yellow, chrome yellow, iron oxide, zinc, cobalt and nickel titanate and carbon black (tank and milk) and so on.

Compared with inorganic pigments, the organic pigment has a small specific gravity, a large surface area, a high transparency, a strong coloring property, a high vividness, and a small particle size, but has poor heat resistance, light resistance and chemical resistance. In recent years, the development of a number of macromolecules of pigment to a certain extent, to overcome the shortcomings of the widely used organic pigments are:

Phthalocyanine pigments - phthalocyanine blue, phthalocyanine green and the like. With bright colors, strong coloring, light and heat resistance, resistance and other excellent properties.

Azo pigments - insoluble pigments containing monoazo or dibasic krypton are widely used, have complete chromatograms, are brightly colored, have higher fastness, but are less heat resistant.

Polyazo pigment - pigment molecular weight, the structure is more complex, the main feature is to improve the insoluble azo pigment heat resistance.

Reduced pigment - is characterized by full color chromatography and high color fastness. It includes ring, anthraquinone, naphthalene anhydride, pyrene anhydride and other pigments.

Different pigments on the masterbatch preparation process has different requirements. Such as the use of inorganic pigments, need to configure the paint grinding system. If grinding in the solvent phase also consider the problem of phase conversion. Organic pigments, especially oil-soluble pigments, are better able to dissolve in the dispersant, eliminating the need for grinding systems.

Paint on the proportion of dispersant requirements are different, in general, inorganic pigment surface area is small, the amount of dispersant is also small, the ratio of 60:40; and organic pigment surface area, the amount of dispersant is also large, the ratio of 40 : 60.

Pigments also affect the fiber formation of polypropylene, mainly in the melt rheological properties, filtration performance, crystallization performance and fiber processing performance. Carbon black, titanium white, phthalocyanine blue, phthalocyanine green and polypropylene affinity is poor, the melt flow viscosity increases, the crystallinity increases, fiber performance deterioration. Azo-type pigment to melt viscosity decreased, fiber performance has improved.

The effects of pigments on the rheological properties of polypropylene melt have been studied. It is believed that the addition of carbon black, phthalocyanine blue and titanium dioxide will degrade the flow properties of polypropylene. Adding GL orange and BR red will help Improvement of flowability of polypropylene. It is also pointed out that the mixing of the pigment and the polypropylene is a heterogeneous system. Mixing the viscosity of the larger, in the processing must ensure adequate mixing time and shear force.
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