Clarity, low haze polymer
AssigneeSunoco, Inc. (R&M)
InventorsThomas Gallagher, Edwin B. Townsend, IV
Life of this patent
Estimating the term…
Abstract
A method of manufacturing an improved clarity, low haze, low melt flow rate homopolymer polypropylene and thermoformed parts therefrom using an additive package such that the additive package alone provides the improved qualities, and process adjustments at the thermoforming stage are not required. The additive package does not contain a phosphite antioxidant, and the homopolymer polypropylene is either virgin material or virgin material mixed with at least 25 percent reground homopolymer polypropylene of the improved formulation described herein and combined with the improved clarity additive package.
Claims20
A method of manufacturing high clarity thermoformed parts substantially free of phosphite antioxidants comprising
- combining at least one additive selected from the group consisting of non-phosphite antioxidants, nucleating agents, antistatic agents, clarifying agents, and acid scavengers with virgin polypropylene homopolymer to form an improved clarity homopolymer,
- combining said improved clarity homopolymer with reground thermoformed polypropylene homopolymer to create a homopolymer mixture,
- extruding said homopolymer mixture into sheet form, and
- thermoforming said homopolymer mixture.
High clarity thermoformed parts substantially free of phosphite antioxidants, manufactured by a process comprising combining at least one additive selected from the group consisting of non-phosphite antioxidants, nucleating agents, antistatic agents, clarifying agents, and acid scavengers, with virgin polypropylene homopolymer to form an improved clarity homopolymer, combining said improved clarity homopolymer with reground thermoformed polypropylene homopolymer to create a homopolymer mixture, wherein said homopolymer mixture has a melt flow rate of between about 1 and about 4 g/10 min;
- a xylene solubles content of about 2.5 percent to about 4.5 percent;
- and wherein said homopolymer mixture is extruded and thermoformed at a temperature between about 146° C. and about 155° C.
High clarity thermoformed parts substantially free of phosphite antioxidants, said parts having a haze of between about 3 and 5%, wherein said parts are manufactured by a process comprising combining at least one additive selected from the group consisting of non-phosphite antioxidants, nucleating agents, antistatic agents, clarifying agents, and acid scavengers, with virgin polypropylene homopolymer to form an improved clarity homopolymer, combining said improved clarity homopolymer with reground thermoformed polypropylene homopolymer to create a homopolymer mixture, wherein said homopolymer mixture is extruded, and thermoformed at a temperature between about 146° C. and about 155° C.
An improved clarity homopolymer, substantially free of phosphite antioxidants, comprising reground thermoformed polypropylene homopolymer, virgin polypropylene homopolymer, and an additive package, said additive package containing a non-phosphite antioxidant, and at least one additive selected from the group consisting of nucleating agents, antistatic agents, clarifying agents, and acid scavengers.
High clarity thermoformed parts substantially free of phosphite antioxidants having a haze of less than about 7% and clarity of greater than about 80%, wherein said parts are manufactured by a process comprising combining at least one additive selected from the group consisting of non-phosphite antioxidants, nucleating agents, antistatic agents, clarifying agents, and acid scavengers, with virgin polypropylene homopolymer to form an improved clarity homopolymer, and combining said improved clarity homopolymer with reground thermoformed polypropylene homopolymer to create a homopolymer mixture, wherein said homopolymer mixture is extruded, and thermoformed at a temperature between about 146° C. and about 155° C.
Dependencies are inferred from the claim text.