Technologies

Medical Urethanes

Processing Information

Processing Conditions
Lubrizol melt processible polyurethanes are shipped as pellets, convenient for use in conventional extrusion and injection molding equipment. The following information is given to provide general processing criteria and should be used as guidelines only. Because polyurethanes are heat and shear sensitive, excessive screw speed, moisture content, back pressure or residence time can result in voids, bubbles, discoloration and other material defects in the finished part. The temperature profiles provided may have to be adjusted to optimize the polymer conversion process with regard to all the variables peculiar to a particular machine or process.
Drying
Lubrizol polyurethanes for medical applications are hygroscopic (they attract and hold water) and will pick up moisture if left exposed to ambient air. The pellets, therefore, must be dried prior to use. To dry and protect the resin and maximize its processibility and final part properties, a machine mounted automatic regenerating desiccant type hopper dryer is essential. The dryer must be capable of reaching and maintaining a -20°F dew point (a minimum -40°F is preferred). Prior to processing, the material must be dried for at least 3 to 4 hours with a dryer inlet air temperature of 150°F (180°F for Tecothane® Shore D resins). If the material is to be pre-dried for extended periods of time, such as overnight, a reduced inlet temperature (reduce by 20-30°F) is suggested. Excessive temperatures (over 180°F for Tecothane® TPUs, over 150°F for all others) can cause bridging and/or throat blockage. A hopper stirrer may be used if bridging occurs in the feed throat of smaller machines. Lubrizol strongly recommends that the materials be dried to a moisture content equal to or less than .05% prior to processing.
TOP Injection Molding Processing Information
The following information provides a starting point for the injection molding of Lubrizol medical grade polyurethane resins. The information presented is based on parts molded on a Newbury 4 oz. 75 ton and/or a Boy 15 ton reciprocating screw injection molding machine. Processing conditions may vary depending on part design, shot size, machine type and make, and mold design.

Screw:	General purpose screw with a compression ratio between 2.5:1 and 3.5:1.
Barrel:	There should be at least 3 heating zones on the machine being used.
Molds:	The mold should be cored for cooling. Stripper plates work well with softer durometers. Knock-out pins are usually sufficient for the higher durometers. Surface impregnated mold releases are recommended for long production runs.
Gates and Runners:	Polyurethanes are shear sensitive. Gates should be generous in size to help minimize stresses. We suggest a 1.0 mm gate if the part is less than 3 grams; 1.5 mm if the part is greater than 3 grams. Full rounded runners (6.3 mm minimum) are recommended.
Operating:	Preferred injection conditions are mid to high pressures (e.g. cavity plastic pressures in 8000 psi range) and slow injection speeds (e.g. 10 grams per second fill rate). Long hold times are recommended (up to 50% of total cycle time) during cooling cycle. Cooling cycles of 30 to 60 seconds or greater, depending on part thickness, are desirable.
Post Molding Considerations:	Stacking parts after molding should be avoided especially during the first 15 to 20 minutes due to blocking characteristics of polyurethanes. Distortion may occur if parts are not placed in horizontal position when removed from the mold.

TOP
Injection Molding Guidelines
The following tables are suggested set up conditions for the various families of products. Profiles may have to be adjusted to optimize the polymer conversion process for the specific machine or process being used.

TECOFLEX® TPU (Temperature in degrees Fahrenheit / Tolerance ±25 Injection Molding Temperature Profiles
MATERIAL	REAR	FRONT	NOZZLE	MELT	MOLD
EG-80A	310	325	335	<380	40 - 80
EG-85A	325	325	335	<380	40 -80
EG-93A	325	325	335	<385	50 - 100
EG-100A	325	350	360	<410	50 - 110
EG-60D	360	375	380	<410	50 - 120
EG-65D	375	390	400	<430	50 - 120
EG-72D	375	410	410	<440	50 - 130
Note: Softer grades of Tecoflex® TPU can be provided with a mold release added onto the pellets. These products are ordered under the “NJ” designation (instead of EG). Consult your customer service or sales representative for more details.

TECOTHANE® TPU (Temperature in degrees Fahrenheit / Tolerance ±25 Injection Molding Temperature Profiles
MATERIAL	REAR	FRONT	NOZZLE	MELT	MOLD
TT-1074A	340	360	365	<410	50 - 90
TT-1085A	375	385	390	<415	50 -110
TT-1095A	380	395	400	<420	50 - 120
TT-1055D	380	395	405	<435	50 - 130
TT-1065D	380	395	410	<445	50 - 130
TT-1075D-M	380	395	410	<455	50 - 130
TT-2074A-B20	330	350	355	<400	50 - 90
TT-2085A-B20	365	375	380	<410	50 - 110
TT-2095A-B20	370	385	390	<415	50 - 120
TT-2055D-B20	370	385	395	<420	50 - 130
TT-2065D-B20	370	385	400	<435	50 - 130

CARBOTHANE® TPU (Temperature in degrees Fahrenheit / Tolerance ±25 Injection Molding Temperature Profiles
MATERIAL	REAR	FRONT	NOZZLE	MELT	MOLD
PC-3575A	310	350	360	<420	40 - 80
PC-3585A	360	375	385	<430	40 -90
PC-3595A	375	395	400	<440	50 - 110
PC-3555D	375	400	410	<440	50 - 120
PC-3572D	375	390	400	<440	50 - 120

TECOPLAST® TPU (Temperature in degrees Fahrenheit / Tolerance ±25 Injection Molding Temperature Profiles
MATERIAL	REAR	FRONT	NOZZLE	MELT	MOLD
TP-470	430	440	440	<475	90 - 130
OP-770	430	440	440	<475	90 -130

TOP

Extrusion Processing Information
Extruder:	General purpose screws with an L/D ratio of 24:1 and a compression ratio between 2.5:1 and 3.5:1 work well. Lubrizol has found that a medium shear screw, barrier type with mixing in the metering section has been successful in producing single and multi lumen tubing.
Barrel:	It is recommended to have 4 heating zones on the extruder. Good temperature regulation is essential for successfully processing Lubrizol medical-grade resins.
Dies:	Draw down ratios between 1.5:1 and 2:1 aid in reducing built-in stress and help reduce post extrusion shrinkage. All tooling should be streamlined to minimize material hang up and subsequent polymer degradation.
Start Up / Shut Downs:	For startups the machine should be stripped and cleaned if possible. If it is not possible to clean the machine, a purge run with LDPE will help facilitate the changeover from one resin to another. For any shut down longer than a few minutes, the machine should be purged with LDPE and the heats turned off until the next run. This is especially true for all Tecothane® resins or resins that have been filled with bismuth subcarbonate or tungsten. When switching from a soft grade to a hard grade of the same resin family (for example, Tecothane® resins), it is not necessary to purge with LDPE.

TOP
Extrusion Temperature Profiles
The following tables are suggested set up conditions for the various families of products. Profiles may have to be adjusted to optimize the polymer conversion process for the specific machine or process being used.

TECOFLEX® TPU (Material Temperatures in Fahrenheit / Tolerance ±25)
PRODUCT	ZONE 1	ZONE 2	ZONE 3	ZONE 4	MELT	DIE	PRESSURE	SCREEN PACK
EG-80A	330	340	350	360	360	360	1,000 - 2,500 psi	500 mesh
EG-85A	340	350	360	360	360	360	1,000 - 2,500 psi	500 mesh
EG-93A	350	360	370	380	380	380	1,000 - 2,500 psi	500 mesh
EG-100A	360	370	380	390	390	390	2,000 - 4,000 psi	500 mesh
EG-60D	360	370	380	390	390	390	2,000 - 4,000 psi	500 mesh
EG-65D	360	370	380	390	390	390	2,000 - 4,000 psi	500 mesh
EG-72D	370	380	390	400	400	400	2,000 - 4,000 psi	500 mesh

EG-80A-B20	330	340	350	360	360	360	1,000 - 2,500 psi	250 mesh
EG-85A-B20	340	350	360	360	360	360	1,000 - 2,500 psi	250 mesh
EG-93A-B20	350	360	370	370	370	370	2,000 - 4,000 psi	250 mesh
EG-100A-B20	350	360	370	370	370	370	2,000 - 4,000 psi	250 mesh
EG-60D-B20	350	360	370	370	370	370	2,000 - 4,000 psi	250 mesh
EG-65D-B20	360	370	380	380	380	380	2,000 - 4,000 psi	250 mesh
EG-72D-B20	360	370	380	380	380	380	2,000 - 4,000 psi	250 mesh
Resin drying requirement: material must maintain 0.05% or less moisture content. Best method: desiccant dry in hopper on extruder at 150°F a minimum of 4 hours after dryer maintains -20°F dew point air flow.

TECOTHANE® TPU (Material Temperatures in Fahrenheit / Tolerance ±25)
PRODUCT	ZONE 1	ZONE 2	ZONE 3	ZONE 4	MELT	DIE	PRESSURE	SCREEN PACK
TT-1074A	390	410	420	420	420	420	1,000 - 2,500 psi	500 mesh
TT-1085A	390	410	420	420	420	420	1,000 - 2,500 psi	500 mesh
TT-1095A	390	420	420	430	430	430	1,000 - 2,500 psi	500 mesh
TT-1055D	390	420	430	430	430	430	1,000 - 2,500 psi	500 mesh
TT-1065D	390	420	430	430	430	430	1,000 - 2,500 psi	500 mesh
TT-1069D	390	400	410	420	420	420	1,000 - 2,500 psi	500 mesh
TT-1072D	390	410	420	430	430	430	1,000 - 2,500 psi	500 mesh
TT-1075D	390	420	430	440	430	430	1,000 - 2,500 psi	500 mesh

TT-2074A-B20	390	400	410	420	420	420	2,000 - 4,000 psi	250 mesh
TT-2085A-B20	390	400	410	420	420	420	2,000 - 4,000 psi	250 mesh
TT-2095A-B20	390	400	410	420	420	420	2,000 - 4,000 psi	250 mesh
TT-2055D-B20	390	400	410	420	420	420	2,000 - 4,000 psi	250 mesh
TT-2065D-B20	390	400	410	420	420	420	2,000 - 4,000 psi	250 mesh
TT-2069D-B20	400	410	420	430	430	420	2,000 - 4,000 psi	250 mesh
TT-2072D-B20	400	410	420	430	430	420	2,000 - 4,000 psi	250 mesh
TT-2075D-B20	390	410	420	430	430	430	2,000 - 4,000 psi	250 mesh
Resin drying requirement: material must maintain 0.05% or less moisture content. Best method: desiccant dry in hopper on extruder at 150°F a minimum of 4 hours after dryer maintains -20°F dew point air flow. (180°F for Shore D resins).

CARBOTHANE® TPU (Material Temperatures in Fahrenheit / Tolerance ±25)
PRODUCT	ZONE 1	ZONE 2	ZONE 3	ZONE 4	MELT	DIE	PRESSURE	SCREEN PACK
PC-3575A	370	380	410	420	420	420	1,000 - 2,500 psi	500 mesh
PC-3585A	370	390	410	420	420	420	1,000 - 2,500 psi	500 mesh
PC-3595A	380	390	410	420	420	420	1,000 - 2,500 psi	500 mesh
PC-3555D	390	400	420	440	430	430	2,000 - 4,000 psi	500 mesh
PC-3572D	390	400	420	440	430	430	2,000 - 4,000 psi	500 mesh

PC-3575A-B20	380	390	410	420	420	420	1,000 - 2,500 psi	250 mesh
PC-3585A-B20	380	390	410	420	420	420	1,000 - 2,500 psi	250 mesh
PC-3595A-B20	390	400	420	420	420	420	1,000 - 2,500 psi	250 mesh
PC-3555D-B20	390	400	420	430	430	420	2,000 - 4,000 psi	250 mesh
PC-3572D-B20	390	400	420	430	430	420	2,000 - 4,000 psi	250 mesh
Resin drying requirement: material must maintain 0.05% or less moisture content. Best method: desiccant dry in hopper on extruder at 150°F a minimum of 4 hours after dryer maintains -20°F dew point air flow. (180°F for Shore D resins).

TECOPHILIC® TPU (Material Temperatures in Fahrenheit / Tolerance ±25)
PRODUCT	ZONE 1	ZONE 2	ZONE 3	ZONE 4	MELT	DIE	PRESSURE	SCREEN PACK
HP-60D-60	370	380	390	400	385	385	2,000 - 4,000 psi	500 mesh
HP-60D-35	370	380	390	400	385	385	2,000 - 4,000 psi	500 mesh
HP-60D-20	370	380	390	400	385	385	2,000 - 4,000 psi	500 mesh
HP-93A-100	370	380	390	400	385	385	1,000 - 2,500 psi	500 mesh
Resin drying requirement: material must maintain 0.05% or less moisture content. Best method: desiccant dry in hopper on extruder at 150°F a minimum of 4 hours after dryer maintains -20°F dew point air flow. (180°F for Shore D resins).

Lubrizol disclaims any warranty of its products (Tecoflex®, Tecothane®, Carbothane®, Tecoplast®, Tecophilic® and Tecogel® TPUs) for merchantability or fitness for any particular application. Any person who intends to use these resins in the manufacture of implantable or any other medical device must independently determine the suitability of these resins for such applications. Each person is responsible for obtaining all necessary FDA and other approvals for the use of these resins in such an application and for complying with all applicable laws relating to the manufacture and sale of medical devices.

TOP

Solution Processible Grades for Tecoflex® and Tecophilic® TPUs

Specifications
• The solution grades of Tecoflex® and Tecophilic® TPUs have been specially formulated to be dissolved in various solvents for use in solution casting or for coating of medical products. The solution grades differ from the extrusion grades in that they contain no melt processing lubricants.
• Tecoflex® Solution Grade Polyurethanes are available in four hardnesses: 80 Shore A, 85 Shore A, 93 Shore A, and 60 Shore D. Tecophilic® TPUs are available in three hardnesses: 80 Shore A, 93 Shore A and 60 Shore D.
• These are designed to be dissolved in appropriate solvents or lacquer coating of assemblies and component parts.

Solution Preparation

• Tecoflex® and Tecophilic® Solution Grade Polyurethanes are hygroscopic (they attract and hold water); therefore, the pellets may need to be dried prior to preparing solutions.
• The urethane solids should be added to the solvent system of choice and be completely dissolved prior to use.
• Tecoflex® and Tecophilic® Solution Grade Polyurethanes can be dissolved in several solvents, such as Tetrahydrofuran (THF), Dimethylacetamide (DMAC), or Methylene Chloride (MC). THF and MC evaporate more quickly than DMAC. A combination of solvents may be indicated by particular applications. MC may not work as effectively on all Tecophilic® resins.
• Pellets may be solvated in a heated glass reactor held at 60°C (equipped with cold water condenser) or may be solvated at room temperature by rolling in a rotating flask. The heated reactor will solvate the pellets in a few hours, whereas the rotating flask may require two days to solvate high resin percentages.
• The recommended solids content, by weight, for initial trials are 80A (3-6%); 85A (4-7%); 93A (4-7%); 60D (4-7%).
• The viscosity of the lacquer solution is directly related to solids content and affects the uniformity and consistency of the finished product. Viscosity can be increased by adding more solids or decreased by adding more solvent.

Lacquer Dip Casting

• Mandrels of the desired shapes should be cleaned with acetone prior to use.
• In many cases, elevated temperature can facilitate lacquer application. Recommended starting temperatures are 55°C for the mandrel and 65°C for the lacquer solution. These temperatures should be used only with DMAC. THF and MC do not require heating.
• Test runs are necessary to optimize the solids content and viscosity required for application.
• The eventual thickness of each layer will be determined by the solids content, whereas the ease of application will be determined by the viscosity.
• The mandrel should be introduced gradually into the lacquer until the mandrel is completely covered, and then withdrawn at a controlled rate that is consistent with the flow rate of the lacquer.
• Each coating should be air or oven dried until a “skin” forms. Subsequent dips should be dried likewise.
• Once the desired thickness is attained, the part should be allowed to deaerate for at least 24 hours prior to demolding or handling.

Lacquer Coating

Follow the same steps as for casting.
At least two coats are recommended for reasonable uniformity and integrity.

Spray Coating

• Spraying should be accomplished with high quality industrial equipment.
• Solution viscosity should be adjusted for uniform spray output.
• Spray coated components should be deaerated for 24 hours prior to handling.

Precautions

• Tecoflex® and Tecophilic® polyurethanes are hygroscopic. Drying may be accomplished in a dessicant dryer for three hours at 65°C or in a circulating oven for five hours at 75°C.
• Solutions and solvents should be handled under a fume hood or in a well-ventilated area.

Site Map

Privacy Statement