PT7988 Shore D-90 Tough Hard Urethane
DESCRIPTION
PT7988
is a two-component polyurethane casting system that cures to a very
hard and durable Shore D 90 elastomer. This system is very easy to
process. The mixed viscosity allows easy filling of complicated closed
molds, and picks up fine details on the pattern. PT7988 has a ½ hour pot
life, which allows time for mixing and deairing, and it cures rapidly
for fast mold turn-around.
PT7988 is particularly well suited for the production of a variety of
patterns, molds and fixtures for the foundry industry. The high cured
hardness let this material perform well in thin cross-section areas on
patterns that might otherwise move and deflect with softer materials.
The red color provides good contrast with typical foundry sand. Also,
PT7988 has good hot strength, so it will not soften when in contact with
hot sand.
PT7988 can be considered a very low hazard potential product, as it does
not contain any toxic or regulated raw materials in its makeup. It does
not contain methylene dianiline (MDA), or other potentially harmful
aniline derivatives, nor does it contain MBOCA or TDI, and it does not
include any hazardous or potentially regulated diluents. PT7988 is an
ideal candidate for the most demanding tooling applications where its
high hardness, tough cured properties, very good abrasion resistance and
good hot strength allow it to perform well.
PRODUCT SPECIFICATIONS
| PT7988 A | PT7988 B | ASTM Method | |
| Color | Brown | Reddish Brown | Visual |
| Viscosity | 260 cps | 14000 cps | D2392 |
| Specific Gravity, gms./cc | 1.229 | 1.747 | D1475 |
| Mix Ratio, by Weight | 50 A : 100 B | PTM&W | |
| Pot Life, 4 fl oz Mass @ 77°F | 25 – 30 minutes | 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.
PT7988 is a fairly rapid curing material, and can develop handling
properties sufficient for demolding in a few hours at room temperature.
This feature will allow more rapid production of multiple pattern sets
for the same master in a short time. In a single work shift, PT7988
castings can be demolded and set aside to complete the cure, while an
additional casting is made off the pattern, and subsequently demolded on
the following shift.
PACKAGING WEIGHTS
| Gallon Kit | Pail | |
| PT7988 A | 5.75 lb. | 50 lb. |
| PT7988 B | 11.5 lb. | 100 lb. (2 @ 50 lb.) |
| Kit | 17.25 lb. | 150 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
| PT7988 A/B | ASTM Method | |
| Mix Ratio, by Weight | 50 A : 100B | PTM&W |
| Color | Reddish Brown | Visual |
| Mixed Viscosity, @77°F, centipoise | 5000 cps | D2393 |
| Working Time, 4 fl. oz. Mass @ 77°F | 25 – 30 min. | D2471 |
| Cured Hardness, Shore D | 90 Shore D | D2240 |
| Shrinkage, in/in, Mold #1, Vol: .053 Gal | .001 | D2566 |
| Specific Gravity, grams, cc | 1.61 | D1475 |
| Density, lb./cu. in. | .0581 | D792 |
| Specific Volume, cu. in./lb. | 17.2 | D792 |
| Tensile Strength, psi | 6298 psi | D638 |
| Elongation at Break, % | 6.51 % | D638 |
| Tensile Modulus, psi | 723,590 psi | D412 |
| Flexural Strength, Cast Bar | 11,194 psi | D790 |
| Flexural Modulus, Cast Bar | 767,852 psi | D790 |
| Glass Transition Temperature, Tg, DMA | 137°F | 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.