PT7275 & PT7280 Midrange Hardness Flexible Urethane Elastomers
DESCRIPTION
The
Shore A-75 and A-80 urethane systems described here are tough
elastomeric materials in the middle range hardness for flexible
urethanes that have good handling and cured properties. Their slightly
tougher nature, compared to softer materials, makes them ideal for
applications such as metal forming dies, high strength flexible molds,
abrasion resistant shapes and parts, cutting pads, fixtures and flexible
parts. Both systems are light colored materials that release air very
well and pour easily.
PT7275 and PT7280 are very clear systems, and are low in color, so they
can be tinted with either transparent or opaque dyes or pigments to give
a variety of colored castings. These two systems can be considered very
low hazard potential products, as they do not contain any toxic or
regulated raw materials in their makeup. They do not contain methylene
dianiline (MDA), or other potentially harmful aniline derivatives, nor
do they contain MBOCA or TDI, and they do not contain any hazardous or
potentially regulated diluents.
PRODUCT SPECIFICATIONS
Shore A-75 System | Shore A-80 System | ||||
PT7275 A | PT7275 B | PT7280 A | PT7280 B | ASTM Method | |
Color | Light Amber | Amber | Light Amber | Amber | Visual |
Viscosity | 7000 cps | 175 cps | 2500 cps | 200 cps | D2392 |
Specific Gravity, gms./cc | 1.06 | 1.01 | 1.03 | 1.07 | D1475 |
Mix Ratio, by Weight | 100 : 30 | 100 : 80 | PTM&W | ||
Pot Life, 4 fl oz Mass @ 77°F | 30 min. | 25 – 30 min. | D2471 |
HANDLING & CURING
Generally, with polyurethane elastomers, full properties are developed
in 7 days at room temperature (75°F). Temperatures below 75°F will
lengthen the cure time, and if the ambient temperature is below 60°F,
additional heat may be necessary for proper cure. Elevated temperatures
will accelerate the cure of urethanes, but care must be taken if a
higher temperature is used to cure the material. Generally, the higher
the curing temperature, the greater the final cured shrinkage. When heat
curing for more rapid processing, to best control shrinkage, the
casting should be allowed to set for 12 to 18 hours at room temperature
before an oven post cure. A typical accelerated curing cycle, therefore,
would be: Allow to gel on the pattern for 12 to 18 hours at room
temperature (70°F to 80°F), then post cure for a minimum of 8 hours at
150°F to 165°F and allow to cool before demolding.
PACKAGING WEIGHTS
Gallon Kit | Pail | |
PT7275 Part A | 8 lb. | 40 lb. |
PT7275 Part B | 2.4 lb. | 12 lb. |
Kit | 10.4 lb. | 52 lb. |
PT7280 Part A | 8 lb. | 40 lb. |
PT7280 Part B | 6.5 lb. | 32 lb. |
Kit | 13.5 lb. | 72 lb. |
Inasmuch
as PTM&W Industries, Inc. has no control over the use to which
others may put material, it does not guarantee that the same results as
those described herein will be obtained. The above data was obtained
under laboratory conditions, and to the best of our knowledge is
accurate. This information is presented in good faith to assist the
user in determining whether our products are suitable for his
application. No warranty or representation, however is intended or
made, nor is protection from any law or patent to be inferred, and all
patent rights are reserved. Before using, user shall determine the
suitability of the product for his intended use, and user assumes all
risk and liability whatsoever in connection therewith. In no event with
PTM&W Industries, Inc. be liable for incidental or consequential
damages. Buyer’s sole and exclusive remedy in such instances shall be
limited to replacement of the purchase price.
TYPICAL MECHANICAL PROPERTIES
PT7275 A/B | PT7280 A/B | ASTM Method | |
Mix Ratio, by Weight | 100 : 30 | 100 : 80 | PTM&W |
Color | Amber | Amber | Visual |
Mixed Viscosity, @77°F, centipoise | 3000 cps | 1550 cps | D2393 |
Working Time, 4 fl. oz. Mass @ 77°F | 30 min. | 23 – 30 min. | D2471 |
Cured Hardness, Shore D | 75 A±5 | 80 A±5 | D2240 |
Shrinkage, in/in, Mold #1, Vol: .053 Gal | .0009 | .0003 | D2566 |
Specific Gravity, grams, cc | 1.048 | 1.05 | D1475 |
Density, lb./cu. in. | .0379 | .0379 | D792 |
Specific Volume, cu. in./lb. | 26.4 | 26.5 | D792 |
Tensile Strength, psi | 2250 psi | 2785 psi | D638 |
Elongation at Break, % | 755 % | 800 % | D638 |
Tear Strength, Die C, pli | 305 pli | 352 pli | D624 |
Compression Set, Method B | 76 % | 80 % | D395 |
Bashore Rebound | 45 % | 39 % | D2632 |
Taber Abrasion, H18 Wheel, 1000, grams, 1000 cycles, mg loss | 23 mg | 33 mg | D1044 |
SAFETY & HANDLING
PTM&W epoxy products are made from raw materials carefully chosen to minimize or even eliminate toxic chemicals, and therefore offer the user high performance products with minimum hazard potential when properly used. Generally, the PTM&W epoxy resins and hardeners will present no handling problems if users exercise care to protect the skin and eyes, and if good ventilation is provided in the work areas. However, all epoxy resins and hardeners can be irritating to the skin, and prolonged contact may result in sensitization; and breathing of mist or vapors may cause allergenic respiratory reactions, especially in highly sensitive individuals. As such, avoid contact with eyes and skin, and avoid breathing vapors. Wear protective rubber apron, clothing, gloves, face shield or other items are required to prevent contact with the skin. In case of skin contact, immediately wash with soap and water, followed by a rinse of the area with vinegar, and then a further wash with soap and water. The vinegar will neutralize the hardener and lessen the chances of long term effects. Use goggles, a face shield, safety glasses or other items as required to prevent contact with the eyes. If material gets into the eyes, immediately flush with water for at least 15 minutes and call a physician. Generally, keep the work area as uncluttered and clean as possible, and clean up any minor spills immediately to prevent accidental skin contact at a later time. Keep tools clean and properly stored. Dispose of trash and empty containers properly. Do not use any of these types of products until Material Safety Data Sheets have been read and understood.