Masterbatch is a new type of polymer material colorant, also known as pigment masterbatch. It is composed of three basic elements: pigments or dyes, carriers, and additives. It is a concentrated mixture obtained by uniformly dispersing high-performance pigments or dyes into a resin carrier. It can also be referred to as a pigment concentrate, which gives it strong coloring strength. Since pigments themselves already have high tinting power, how is masterbatch blending carried out?
The use of masterbatch in injection-molded plastic parts is a complex issue. Although it is often not fully considered during early project planning, it should be carefully evaluated during material selection. This process involves several key steps.
The selection of colored resins depends on multiple factors, including the type of resin used and the final application, which in turn affect durability requirements, environmental conditions, and production cost.
Colorants/masterbatch can be dyes, pigments, or primary color materials. Pigments are insoluble in resins, while dyes are soluble in resin solutions and are easier to mix. They are commonly used for coloring transparent plastics and applications requiring bright, vivid colors. Dyes provide bright colors but may not hide surface defects as effectively as pigments. However, dyes generally perform poorly in outdoor applications.
Colorants can be partially soluble or insoluble. Organic pigments are more effective than inorganic pigments in terms of tinting strength and color fastness, producing brighter and more vivid colors even at low dosages. They are also suitable for transparent plastic applications. Inorganic pigments have poorer flow characteristics compared to organic dyes and pigments and are often used in applications where higher opacity is required. Compared with dyes and organic pigments, inorganic pigments also offer excellent heat resistance and weather resistance.
Adding colorants or masterbatch into resin can affect the performance of the final plastic parts. Therefore, compatibility between the chemical structure of the polymer and the colorant must be carefully considered. The impact of colorants on polymer properties also depends on their dosage. Some compounds in colorants may disrupt the chemical structure of polymers and reduce their original properties, such as impact resistance. High processing temperatures used in injection molding may further influence the degree of interaction between colorants and polymers.
There are various plastic coloring methods, including masterbatch coloring, compound blending, surface coating coloring, and dry blending. The chosen method can affect the mechanical properties of plastics. For example, in compound coloring methods, natural pigment particles are mixed with high-pigment-concentration pellets. Since most polymers are not miscible with other polymers, attention must be paid to ensuring material compatibility.