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US 8,841,412 B2Granted
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
Life of this patent
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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.
Claims18
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 above a lower limit 50 ppm and below an upper limit of 1000 ppm as the polymer resin is fed into the extruder,
- wherein the moisture content is maintained above the lower limit to allow for plasticization of polymer resin melt in the extruder which decreases its viscosity which reduces monomer generation and molecular weight loss in the polymer resin melt,
- wherein the moisture content is maintained below the upper limit reduces molecular weight loss in the polymer resin melt due to hydrolytic degradation;
- 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 feed above the lower limit and below the upper limit.
4 more elements
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 feed during the extrusion process prior to being fed into the extruder to remove moisture from the polymer resin feed, wherein the drying gas has substantially no moisture content prior to passing through the polymer resin;
- maintaining the moisture content of the polymer resin feed during the extrusion process prior to being fed into the extruder above a lower limit of 50 ppm and below an upper limit of 1000 ppm as the polymer resin is fed into the extruder,
- wherein the moisture content is maintained above the lower limit to allow for plasticization of polymer resin melt in the extruder which decreases its viscosity which reduces monomer generation and molecular weight loss in the polymer resin melt,
- wherein the moisture content is maintained below the upper limit to reduce molecular weight loss in the polymer resin melt due to hydrolytic degradation;
- 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 feed above the lower limit and below the upper limit,
- wherein the temperature of the drying gas is decreased to maintain the moisture content of the polymer resin feed above the lower limit, and
- wherein the flow rate of the drying case is decreased to maintain the moisture content of the polymer resin feed above the lower limit.
6 more elements
Dependencies are inferred from the claim text.