In the plastics industry, achieving a quality product in terms of color uniformity in the final product is of particular importance. The stain on the finished product due to the lack of proper pigment distribution is one of the problems that manufacturers face. One of the reasons for this can be the consumption pigment, so because of the importance of this problem in the present article, it is discussed in detail.

Introduction:

In terms of morphology, powder pigments include bulk primary particles and agglomerates. The clumps are formed by the aggregation of primary particles together under the influence of electrostatic or chemical forces. However, clusters are created by the aggregation of primary particles or masses together by van der Waals forces. The clusters are weak and the clusters are stuck together, so dispersive processes cannot break clusters but are able to separate cluster particles.

Powdered pigments contain clumps that aggregate and form clusters. Pigment clusters in the masterbatch production pathway can cause many problems, some of which are:

Variation in color shade and color intensity
Rapid clogging of filters, filters and filters
Fracture in fibers, production of spun fibers
Creating cracks in foil
The destructive effects on the mechanical properties of the polymer
Creating a speckled appearance
Concentration of stress resulting in fracture

Such problems can be solved by preparing the pigment before production and thus by distributing it better. One of the most important prerequisites for good dispersion of pigments to enhance the quality of the finished product is to thoroughly moisten the pigment bundle. This wetting must take place not only on the surface of the nests but also inside and outside them. Distributive factors are used for this purpose.

Distributive factors:

Dispersing agents are necessary to achieve a uniform distribution of pigments or fillers in the composition of materials to produce masterbatches and mixtures, as well as to prevent the formation of agglomerates and their reduction.

In fact, in the scattering process, the pigment is distributed throughout the matrix by reducing the size of the clumps and creating primary and bulk particles or forming smaller clumps. The purpose of the dispersion process is:

Fracture of the joints by mechanical shear force
The wetting of the pigment particles surface
Distribution of pigmented particles throughout the environment
Stabilize the solids and prevent them from recirculating

The three main groups used as dispersing agents are:

Natural and synthetic waxes
Derivatives of organic acids, such as fatty acids, amides or esters of acids
Polycarbonate derivatives, such as polyacrylates, carbon fluorinated polymers

In the plastics industry, waxes are widely used. Waxes are low molecular weight polymers that are used to disperse pigments or other additives. One of the most widely used vaccines for the production of masterbatches is polyethylene wax. Also known as PE Wax, it is a low molecular weight polyethylene consisting of single chain ethylene chains and has a wide variety of uses and applications. PE wax is a byproduct of polyethylene production in both HDPE and LDPE is available and comes in many different types.

The pigment clumps and clumps break down into smaller particles as a result of high shear forces. If this process is performed in the presence of dispersing agents, it results in improved performance in reducing the formation of pigment clusters and clusters. Among the pigments, the process of dispersing the two soot pigments and titanium dioxide is much more difficult than other pigments. Therefore, the use of dispersing agents to produce their masterbatches is very effective in product quality.

It should be noted that the dispersant has good compatibility with the polymer so as not to affect the color quality of the finished product. For example, the dispersant suitable for polyolefin colored masterbatches is usually low molecular weight polyethylene wax or zinc stearate, etc., while for colored masterbatches, engineering plastics are usually made of low molecular weight polarized polyethylene wax. Such as wax oxidation, magnesium stearate, calcium stearate, etc. are used. On the other hand, it should be noted that moisture is usually detrimental to pigment distribution. Because it increases the likelihood of clumping, this makes it more difficult to pigment in nonpolar environments.

The effect of viscosity

It is recommended to use a certain amount of wax to significantly improve the pigment wettability and its distribution. On the other hand, this value reduces the viscosity of the masterbatch melt, resulting in better pigment distribution and increased color efficiency. By reducing the viscosity caused by the addition of wax, the potential for increasing pigment content in the masterbatch produced without any negative effect is provided. In addition, with the addition of wax, the viscosity of the masterbatch melt containing polyethylene wax is reduced, resulting in easier mixing of the device and a significant increase in production rate. As a result of the capillary effect, the wax enters the intercostal space, so a lower viscosity wax is more advantageous than a higher viscosity wax.

Advantages of Polyethylene Wax in Masterbatches

Generally, the use of dispersive additives for pigments as well as fillers has the following advantages:

Increased color intensity
Excellent dilution capability
Great movie transparency
Reduce stain formation
Reduce clutter and clutter
Reduction of clump reorganization in downstream processes
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