Flexible rubbers
Overview
Flexible rubbers are different from the other resins previously described in that the have high elongation( up to 600% their original form) . Flexible rubbers are determined by their shore A or D hardness.
Applications range from flexible moulds for polyester resins , to polyurethane moulds for concrete to gaskets, rollers , enigineered parts , prototyping , etc.
Basically, there are five different types of flexible mold compounds in significant use today: polyurethanes, polysulfides, silicones, latex and hot melts. Each type has some advantages and disadvantages over the other types.
The "Hot-Melt" (polyvinyl chloride) systems are inexpensive, since the worn moulds can be melted and recast. However, they are hazardous to handle because of the high temperatures required for melting.
Latex has the advantage of producing a very elastic, thin-walled, strong mold, but shrinkage is high and molds must be supported to prevent distortion. Because as many as 10 to 20 brush coats must be applied for adequate thickness, with time allowed to "dry" in between each coat, making the mold is slow and time consuming.
Silicone rubbers make excellent molds for casting resins and foams, but material cost is extremely high.
Polyurethane flexible mold compounds have limited shelf stability and are "moisture conscious", but they are easy to handle with simple mixing ratios and good fluidity. They can be used for pouring practically any type of cementitious material, casting resin or foam formulation. Cost of material is far below that of the silicones and appreciably lower than polysulfides.
Product Range
Flexible Polyurethanes
| Code | Description | Application | Gel Time | Info |
|---|---|---|---|---|
| Easyflex 35A | P/U Flexible Shore 35A | Pourable P/U Casting resin 100:50 | 8-15 min |  |
| Easyflex 60A | P/U Flexible Shore 60A | Pourable P/U Casting resin 100:50 | 10 - 15 min | |
| Easyflex 80A | P/U Flexible Shore 80A | Pourable P/U Casting resin 100:33 | 4 - 6 min | |
Silicones
| Code | Description | Application | Gel Time | Info |
|---|---|---|---|---|
| RTVC30 | RTV Silicone Higher Shore | Good for holding shape | 30 - 90 min |
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