US 10,322,561 B2 · Rapid solid-state foaming

Abstract

Disclosed, among other things, are ways to manufacture reduced density thermoplastics using rapid solid-state foaming and machines useful for the saturation of plastic. In one embodiment, a foaming process may involve saturating a semi-crystalline polymer such as Polylactic Acid (PLA) with high levels of gas, and then heating, which may produce a reduced density plastic having high levels of crystallinity. In another embodiment, a foaming process may produce layered structures in reduced density plastics with or without integral skins. In another embodiment, a foaming process may produce deep draw structures in reduced density plastics with or without integral skins. In yet another embodiment, a foaming process may utilize additives, blends, or fillers, for example. In yet another embodiment, a foaming process may involve saturating a semi-crystalline polymer such as Polylactic Acid (PLA) with high levels of gas, and then heating, which may produce a reduced density plastic having high levels of crystallinity.

Claims29

Dependent claims

A method, comprising:

inserting a polylactic acid polymer material into a pressurized chamber via a first dynamic seal;
exposing the polylactic acid polymer material in the pressurized chamber to carbon dioxide at a first pressure and a first temperature for a first time period to at least partially saturate the polylactic acid polymer material with carbon dioxide, the first time period less than about ten minutes;
removing the polylactic acid polymer material from the pressurized chamber via a second dynamic seal;
and
heating the polylactic acid polymer material at a second pressure and a second temperature for a second time period, the second pressure less than the first pressure, and the second temperature greater than the first temperature,
wherein at least one of the first dynamic seal and the second dynamic seal includes a sealing surface configured to maintain a gap of between about 0.002 inches and about 0.005 inches between the sealing surface and the polylactic acid polymer material.

3 more elements

Dependencies are inferred from the claim text.

Rapid solid-state foaming

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Rapid solid-state foaming

Life of this patent

Abstract

Claims29