Selecting Tariff Lines for Importing Polymer Masterbatches
Masterbatch tariff classification hinges on active chemical loading, where inorganic pigments above specific mass thresholds shift import codes from Chapter 39.
Carrier Polymer
Meaning
Base resin for masterbatch production holds pigments or additives in a concentrated state for uniform distribution during injection moulding. Compatibility between the carrier polymer and the let-down resin determines the mechanical integrity of the final part. Choosing a chemically identical resin avoids delamination or loss of tensile strength.
Melt Miscibility
Viscosity matching ensures that the concentrate breaks down and mixes thoroughly during the screw rotation. If the carrier polymer possesses a notably higher melting point than the main resin, unmelted specs appear in the product.
Dispersion Quality
Homogeneous distribution of carbon black or titanium dioxide relies on the wetting ability of the molten carrier. Wetting occurs when the carrier polymer coats individual particles to prevent agglomeration. In polyolefin applications, low-density polyethylene is a frequent choice because of its high melt flow index and broad compatibility range.
Effective wetting reduces the required torque during extrusion and prevents filter screen blinding. High shear forces during the compounding stage further break down additive clumps to ensure color consistency across millions of cycles.
Loading Limit
Saturation points restrict the amount of additive a single resin volume can hold. Once the carrier polymer reaches its capacity, the masterbatch becomes brittle and difficult to pelletize. Economics favor high loadings to reduce the let-down ratio at the moulding machine.