All Purpose Medical Grade Polyurethane with Superior Physical Properties and Lot to Lot Consistency.

We manufacture and market aromatic-based ChronoThane™ P. Characteristics that make it attractive to medical device manufacturers include: low extractables, dimensional stability, gamma sterilizable, and chemical inertness. In addition to these qualities is the ease of thermoplastic processability.

ChronoThane™ P is a family of aromatic ether-based polyurethane elastomers, ranging in hardness from 75 Shore A to 70 Shore D. CT Biomaterials offers this product line as either clear resins or radiopaque grades. ChronoThane™ P may be used as a substitute for Pellethane® in medical devices.

Typical physical properties of ChronoThane™ P-75A are shown below:

ChronoThane™ P elastomers can be processed on conventional extrusion or injection molding equipment. As with all polyurethanes, certain precautions must be taken to ensure trouble-free operations. The most common problem is due to excessive pellet moisture.

ChronoThane™ P pellets should be dried to a moisture content equal to or less than 0.01% by weight prior to melt processing. Since ChronoThane™ P elastomers are highly hygroscopic the pellets must be dried before extrusion. If pellets are not properly dried, ChronoThane™ P tubing will exhibit haze and gels and, under extreme moisture conditions, will appear "foamy."

We recommend a machine-mounted desiccant-type hopper drier, capable of reaching and maintaining a dew point of minus 40ºF. Typically, the pellets must be dried for 3-4 hours with a dryer inlet air temperature of 185-200 ºF.

If overnight drying is employed, a hopper dryer temperature of 120-150 F is usually sufficient to achieve a 0.01% moisture content.

Appearance
Most medical-grade polyurethanes are clear to slightly yellow in their original state. However, aromatic-based polyurethanes may turn yellow to amber as a result of processing, sterilization or exposure to UV light. While this discoloration (which is caused by the formation of chromophoric groups in the MDI portion of the molecular chain) does not affect the physical properties of the product.

Annealing
Annealing can be described as slow crystallization by heat without melting. Annealing improves the properties of segmented polyurethanes associated as the crystallinity increases. For ultimate properties we recommend that ChronoThane™ P tubing be annealed at 175º F for about 2 hours. If dimensional stability becomes an issue, we recommend a lower temperature such as 140ºF.

Processing
Equipment Used: Killion extruder, with a 2" 24/1 (L/D) screw.

Extruder Configuration

We recommend a single-stage, non-vented extruder with a heavy duty, DC variable speed, high torque drive.

FDA Status
The use of ChronoThane™ P in medical devices is not covered by any specific FDA regulation. It is the responsibility of the user to establish safety with the FDA through submission of an individual application.

Technical Service
Our technical personnel stand ready to assist you with processing, product availability, or pricing.

This information has been gathered from standard reference sources and is believed to be accurate and reliable. We make no other warranty, express or implied, that the results obtained from the use of this product or information contained herein shall be merchantable or fit for any particular purpose, or that the use of this product will not infringe any patent. It is offered solely for your consideration, investigation, and verification.