PT7290 & PT7295 Hard Flexible Urethane Elastomers
DESCRIPTION
The
Shore A-90 and Shore A-95 urethane systems described here are harder
flexible elasomers with very tough cured properties that make excellent
metal forming tooling and are useful in many other demanding industrial
applications. Forming dies, die springs, stripper pads, patterns, gears
and tough parts are all applications in which these two elastomers
excel.
PT7290 has a low mixed viscosity and a long pot life, so it is very well
suited to pouring into closed molds, where it easily fills thin cross
sections, and flows through thin pouring spouts readily. It is low in
color and accepts dyes or pigments easily when tinted castings are
required.
PT7295 is black in color, has a slightly higher mixed viscosity, and a
long pot life. This system is ideal for pouring patterns, dies and pads,
where a very tough, slightly flexible material is required. PT7295 will
need slightly larger pouring spouts and vents due to its thicker
consistency.
PT7290 and PT7295 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 include any hazardous or potentially regulated
diluents.
PRODUCT SPECIFICATIONS
| Shore A-90 System | Shore A-95 System | ||||
| PT7290 A | PT7290 B | PT7295 A | PT7295 B | ASTM Method | |
| Color | Amber | Amber | Amber | Black | Visual |
| Viscosity | 2,500 cps | 100 cps | 7,000 cps | Thin Paste | D2392 |
| Specific Gravity, gms./cc | 1.03 | 1.09 | 1.08 | 1.11 | D1475 |
| Mix Ratio, by Weight | 100 : 64 | 100 : 50 | PTM&W | ||
| Pot Life, 4 fl oz Mass @ 77°F | 40 – 45 min. | 40 – 50 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 | |
| PT7290 Part A | 8 lb. | 40 lb. |
| PT7290 Part B | 5.25 lb. | 26 lb. |
| Kit | 13.25 lb. | 66 lb. |
| PT7295 Part A | 8 lb. | 40 lb. |
| PT7295 Part B | 4 lb. | 20 lb. |
| Kit | 12 lb. | 60 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
| PT7290 A/B | PT7295 A/B | ASTM Method | |
| Mix Ratio, by Weight | 100 : 64 | 100 : 50 | PTM&W |
| Color | Light Amber | Black | Visual |
| Mixed Viscosity, @77°F, centipoise | 1800 cps | 5250 cps | D2393 |
| Working Time, 4 fl. oz. Mass @ 77°F | 40 – 45 min. | 45 – 50 min. | D2471 |
| Cured Hardness, Shore D | 90 A±5 | 95A±5 | D2240 |
| Shrinkage, in/in, Mold #1, Vol: .053 Gal | 1.055 | .0397 | D792 |
| Specific Gravity, grams, cc | 1.055 | 1.10 | D1475 |
| Density, lb./cu in | .0381 | .0397 | D792 |
| Specific Volume, cu. in./lb. | 26.3 | 25.2 | D792 |
| Tensile Strength, psi | 3,581 psi | 4,000 psi | D638 |
| Elongation at Break, % | 920 % | 225 % | D638 |
| Tensile Modulus – 100% Elongation | 1,086 psi | 1,620 psi | D412 |
| Tensile Modulus – 200% Elongation | 1,393 psi | 2,0275 psi | D412 |
| Tensile Modulus – 400% Elongation | 2,110 psi | 2,740 psi | D412 |
| Tear Strength, Die C, pli | 430 pli | 525 pli | D624 |
| Compression Set, Method B | 90 % | 43 % | D395 |
| Bashore Rebound | 42 % | 48 % | D2632 |
| Taber Abrasion, H18 Wheel, 1000, grams, 1000 cycles, mg loss | 42 % | 48 % | 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.