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 
ColorLight Amber
AmberLight Amber
AmberVisual
Viscosity
7000 cps
175 cps
2500 cps
200 cps
D2392
Specific Gravity, gms./cc
1.061.011.031.07D1475
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.
Kit10.4 lb.
52 lb.
PT7280 Part A8 lb.40 lb.
PT7280 Part B6.5 lb.
32 lb.
Kit13.5 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/BASTM Method
Mix Ratio, by Weight
100 : 30
100 : 80
PTM&W
ColorAmberAmberVisual
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±5D2240
Shrinkage, in/in, Mold #1, Vol: .053 Gal.0009.0003D2566
Specific Gravity, grams, cc
1.0481.05D1475
Density, lb./cu. in.
.0379.0379D792
Specific Volume,  cu. in./lb.
26.426.5D792
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 B76 %
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.