Importance

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Abstract

Single or multiple colorants are infused into a thermoplastic material during melt processing to form preforms and plastic containers exhibiting a marbleized or swirl-type pattern. A base resin and colorant may be fed into an extruder having an extrusion screw and/or barrel modified in a manner to cause incomplete and non-uniform mixing. The modifications may include notches in some of the flights along the extrusion screw, a reduction in the depth or omission of some of the flights, a reduction in diameter of the extrusion screw, or the provision of a marbleizing torpedo near the discharge nozzle. Other techniques include introducing the colorant into vents present along the barrel, using a barrier screw to keep the components separate along the length of the barrel, using a high pressure pump for introducing the colorant near the discharge nozzle, or using multi-material co-injection techniques for co-injecting the base resin and colorant.

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First Claim