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How Do I Properly Add It To A Material When Using A Masterbatch?
- Oct 10, 2018 -

    The two main factors are the carrier resin used to produce the masterbatch and its molecular weight, which are often not determined by the company that purchased the masterbatch. In addition to some specially required colors, materials which are potentially destructive to polymer properties are generally not used. Granular masterbatches usually contain 30%-50% colorant, and the rest of the polymer system such as carrier resin It is essentially a bond as a colorant.


    The amount of color masterbatch in the final resin is generally 2% - 5%


    If the color masterbatch is properly mixed, the content of the carrier resin in the final mixture is from 1% to 3% or more.


    This makes it the most abundant additive in the additive series, so some details should be noted when selecting the carrier resin.


    Specifically, the carrier resin and the matrix resin should be chemically compatible.


    The best way is to choose the same type of polymer as the matrix resin being filled.


    There are certain scopes of application in these rules.


    For example, nylon 6 can be applied as a carrier resin to the coloration of nylon 66 or nylon 46. These nylons are all compatible and nylon 6 has a lower melting point which promotes good mixing.


    Similarly, polyoxymethylene copolymer can be used as a carrier resin on polyoxymethylene homopolymers, and SAN can also be used as a compatible carrier for ABS (but not polystyrene). In addition, for a plastic alloy, one of the two polymers of the alloy may be used as a carrier resin for the color masterbatch.


    In the production process, if an incompatible resin is used as the carrier, the contaminant is deliberately introduced. In order to avoid pollution, it is generally recommended that the masterbatch processing plant use some carriers which have good compatibility with the final resin product. However, most manufacturers are concerned with how to meet the customer's specified color at the lowest cost.


    One such method is to use inexpensive polymers such as ethylene or ethylene copolymers such as EVA.


    This decision may be due to the fact that the masterbatch manufacturer does not have a deep understanding of how the customer or material shaper feels about the product. Some color masterbatch suppliers used to differentiate themselves from these competitors by adding compatible carriers to the color masterbatch formulation. But more suppliers are committed to price wars, providing a low-cost solution based on the so-called "universal carrier."


    If a manufacturer of plastic barrels for injection molding finds polyethylene particles in the barrel of ABS or PC, it is likely to discard it or pick out unqualified materials. However, downstream manufacturers are polluted by the matrix resin added to the masterbatch, which will still affect the performance of the final product.


    Suppliers that offer a mixture of so-called "salt and pepper" also add some incompatible materials to their own products.


    A supplier of nylon 66 compounds, which uses nylon 6 as a carrier in some mixtures, but in most cases EVA will be used. At the normal processing temperature of nylon 66, the ethylene-acetate vinegar in EVA begins to undergo thermal degradation, and the by-products produced may cause wear of the screw and cause appearance problems, especially in places close to the pouring day and the weld line.


    Some materials, such as polypropylene, are adversely affected by the use of incompatible carrier resin colorants. An example shows the use of multiple living hinges to attach a lid to a fragrance container. There are some colors, the parts run without any problems, and the hinges look normal. In addition, the hinges of other colors have a tendency to slowly release outward from the article, and a destructive break occurs after several bending. This difference in performance is not due to the colorant but to the incompatibility of the carrier resin in the masterbatch with the base resin, which is eliminated after correction of the masterbatch carrier resin.


    Assuming that the carrier resin and the matrix resin are compatible, the second important attribute is the molecular weight of the carrier, which is usually expressed in terms of melt flow rate (MFR). In general, in order to promote better mixing in color masterbatch formulation, a resin having a higher melt flow rate than the matrix resin to be colored is generally selected as a carrier. For example, a polycarbonate having an MFR of 10 g/10 min can be used as a color masterbatch with an MFR of 20-30 g/10 min. The high-mole color masterbatch is easier to flow ideally in the screw and is more easily dispersed in a large number of primary materials.


    But this method often has drawbacks.


    Sometimes the link between MFR and molecular weight is neglected, and molecular weight will more directly affect subsequent performance. For high MFR carrier resins, the possibility of a decrease in product performance in the final molded portion is greatly increased.


    In the use of color masterbatch for polyolefin products, high-melting LLDPE resin is widely used as a carrier resin. According to different product requirements, LLDPE grades with different melt indices are selected as carrier resins. The masterbatch manufacturer can design different masterbatch formulations according to whether the processing process of the product is injection molding or extrusion, the flow of the base resin, and the final mechanical conditions of the product.