Controlling Moisture In And Plasticization Of Bioresorbable Polymer For Melt Processing
AssigneeAbbott Cardiovascular Systems Inc.
InventorsBethany Steichen, Stephen D. Pacetti, Manish Gada, Thierry Glauser, Lothar W. Kleiner, Yunbing Wang, James P. Oberhauser, Ni Ding
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Abstract
Methods and systems for controlling the moisture content of biodegradable and bioresorbable polymer resin during extrusion above a lower limit that allows for plasticization of the polymer resin melt and below an upper limit to reduce or prevent molecular weight loss are disclosed. Methods are further disclosed involving plasticization of a polymer resin for feeding into an extruder with carbon dioxide and freon.
Claims23
A method comprising:
- providing a bioresorbable polymer resin as feed to an extruder for an extrusion process;
- passing a drying gas through the polymer resin during the extrusion process prior to being fed into the extruder to remove moisture from the polymer resin, wherein the drying gas has substantially no moisture content prior to passing through the polymer resin;
- maintaining the moisture content of the polymer resin during the extrusion process prior to being fed into the extruder in a selected range between 50 ppm and 1000 ppm;
- and
- adjusting the temperature of the drying gas, the flow rate of the drying gas, or both to maintain the moisture content of the polymer resin in the selected range.
A method comprising
- providing a bioresorbable polymer resin as feed to an extruder for an extrusion process;
- controlling the moisture content of the polymer resin during the extrusion process prior to feeding to the extruder to be within a selected range between 50 ppm and 1000 ppm;
- and
- adjusting the moisture content of a drying gas stream passing through the polymer resin to control the moisture content of the polymer resin.
A system comprising:
- a resin hopper drier for holding polymer resin having an outlet port for connecting to an extruder for feeding the polymer resin through the outlet port to the extruder;
- a source of a dry gas stream and conduits for carrying the dry gas stream from the dry gas stream source;
- a source of a moist gas stream and a conduit for carrying the moist gas stream from the moist gas stream source,
- wherein the conduit from the moist gas stream source is configured to inject the moist gas stream into the dry gas stream to form a drying gas stream;
- a conduit for carrying the drying gas stream into a gas inlet port to the resin hopper;
- a conduit for carrying the drying gas stream from a gas outlet port from the resin hopper;
- a sensor to monitor moisture content of the drying gas;
- and
- a controller that generates a signal to adjust the moisture content of the drying gas based on the monitored moisture content of the drying gas.
A method comprising
- providing a biodegradable polymer resin as feed to an extruder for an extrusion process;
- and
- passing a gas containing carbon dioxide through the polymer resin prior to entering the extruder during the extrusion process,
- wherein the polymer resin absorbs some of the carbon dioxide which reduces melt viscosity of the polymer resin in the extruder during the extrusion process.
A method comprising:
- providing a biodegradable polymer resin as feed to an extruder for an extrusion process;
- and
- passing a gas containing freon through the polymer resin prior to entering the extruder during the extrusion process,
- wherein the polymer resin absorbs some of the freon which reduces melt viscosity of the polymer resin in the extruder during the extrusion process.
Dependencies are inferred from the claim text.