Microcellular foam sheet and processes of making and using
AssigneeDart Container Corporation
InventorChengtao Li
Life of this patent
Estimating the term…
Abstract
A solid state foaming process for generating a microcellular foam sheet for use in forming a container is provided includes a pre-foaming treatment phase prior to a solid state impregnation and foaming phase. The solid state microcellular foam sheet includes a central foamed section defining a foam layer within the microcellular foam sheet having a first population of cells within which are interspersed a second population of cells.
Claims20
A solid state foaming process for generating a microcellular foam sheet for use in forming a container, the process comprising:
- extruding a first layer including a first polymeric material and a blowing agent, wherein the first layer has a first density;
- a first expansion comprising at least partially expanding the first layer with the blowing agent to form a pre-foamed sheet comprising a pre-foamed layer having a second density, less than the first density;
- impregnating the pre-foamed layer in a solid state with a non-reacting gas that is soluble in the first polymeric material, proceeding until a predetermined concentration of the non-reacting gas in the first polymeric material is in the range of about 3.5 to 6 wt. %;
- and
- a second expansion comprising at least partially expanding the pre-foamed layer with the non-reacting gas to form a microcellular foam layer having a third density, less than the second density.
A solid state foaming process for generating a microcellular foam sheet for use in forming a container, the process comprising:
- extruding a first layer including a first polymeric material and a blowing agent, wherein the first layer has a first density;
- a first expansion comprising at least partially expanding the first layer with the blowing agent to form a pre-foamed sheet comprising a pre-foamed layer having a second density, less than the first density;
- impregnating the pre-foamed layer in a solid state with a non-reacting gas that is soluble in the first polymeric material;
- and
- a second expansion comprising at least partially expanding the pre-foamed layer with the non-reacting gas to form a microcellular foam layer having a third density, less than the second density, wherein the microcellular foam layer comprises a central foam section having a first population of cells within which are interspersed a second population of cells having a smaller cell size than the first population of cells.
A solid state foaming process for generating a microcellular foam sheet for use in forming a container, the process comprising:
- extruding a first layer including a first polymeric material and a blowing agent, wherein the first layer has a first density;
- a first expansion comprising at least partially expanding the first layer with the blowing agent to form a pre-foamed sheet comprising a pre-foamed layer having a second density, less than the first density;
- impregnating the pre-foamed layer in a solid state with a non-reacting gas that is soluble in the first polymeric material;
- and
- a second expansion comprising at least partially expanding the pre-foamed layer with the non-reacting gas to form a microcellular foam layer having a third density, less than the second density, wherein the second density is less than the first density by about 12% or less and the third density is less than the second density by about 35 to 65%.
Dependencies are inferred from the claim text.