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PT Flex 50 -Ultra Flexible Polyurethane Rubber -
432024101
€26.70
32,31 € Tax incl.
32,31 € Tax incl.
Shore A50 polyurethane rubber, 1A:1B mix ratio by weight, 5 min pot life and 2-hour cure. The most flexible in the range, 200% elongation.
PT Flex 50 is a two-part polyurethane rubber with Shore A50 hardness, designed for parts that need extra flexibility and stretch without giving up strength. Its low viscosity makes casting easy, its 1A:1B mix ratio simplifies workshop work, and the result is a very flexible part with high elongation and a translucent amber finish. Free from phthalates, mercury and MOCA.
Technical specifications
| Parameter | Value |
|---|---|
| Material type | Two-part polyurethane rubber |
| Shore hardness | A50 |
| Colour | Amber |
| Mix ratio (weight) | 1A : 1B |
| Mixed viscosity | 600 cP |
| Specific gravity | 1.03 (water = 1) |
| Pot life | 5 minutes |
| Cure / demould time | 2 hours |
| Tensile strength | 1.7 MPa (250 psi) |
| Elongation at break | 200 % |
| Maximum service temperature | 60 °C |
| Phthalates / Mercury / MOCA | Free from |
What it is used for
PT Flex 50 is designed for parts that need to flex, stretch and recover their shape without cracking. Its higher elongation at break (200%) within the range makes it especially suitable for:
- Gaskets and sealing parts that work under repeated deformation
- Secondary flexible moulds for parts with moderate undercuts
- Soft-touch grip elements on tools and fixtures
- Props and set pieces that need to flex without breaking
- Functional prototypes of elastomeric parts
- Rollers and low-hardness elements for soft-contact applications
- Reproductions that require more stretch capacity than the rest of the PT Flex range
How to use it
- Prepare the mould or surface. Make sure the mould is clean, dry and free of residue from previous cures. Apply a suitable release agent for polyurethane to all surfaces that will come into contact with the material.
- Condition the components. Bring the part A and part B containers to workshop temperature (20–25 °C). Stir or agitate each component separately before mixing, as they may settle on standing.
- Weigh or measure the parts. Mix part A and part B in a 1A:1B ratio by weight. Use a precision scale for accuracy.
- Mix decisively. Combine both parts for 60–90 seconds, scraping the walls and bottom of the container thoroughly. The pot life is 5 minutes.
- Add pigment if needed. If you want to colour the part, add a few drops of PolyColor Dyes to the mixture before casting. They are compatible and do not affect the cure.
- Pour into the mould. Cast the material in a thin, continuous stream to help air escape. Fill from the lowest point upwards whenever possible.
- Cure time. Leave undisturbed for at least 2 hours at room temperature. After this time the part can be demoulded.
- Demould and post-cure if necessary. For high-performance mechanical applications, a post-cure at moderate temperature (not exceeding 60 °C) can improve final properties.
Important notice — Two-part polyurethanes: polyurethane rubbers are moisture-sensitive. Part A (isocyanate) can gel if exposed to humid air for a prolonged time. Always seal containers immediately after use and store them in a dry place. If the material shows lumps or crystallisation, do not use it: the cure may be compromised. Work in an environment with stable temperature; cold slows down the cure and excessive heat speeds it up unevenly.
Usage tips
Make the most of this hardness's higher elongation
With 200% elongation at break, PT Flex 50 tolerates more stretch than the range's harder grades before breaking. This makes it especially suitable for parts with moderate undercuts that need to flex to be demoulded. Even so, always respect the full cure time before forcing demoulding, since the part keeps gaining mechanical properties over the following hours.
Temperature and humidity in the workshop
The ideal working temperature is between 20 and 25 °C. Below 18 °C the material becomes more viscous, mixing is harder and the cure slows down. Above 30 °C the pot life shortens further. Avoid working in environments with relative humidity above 70 %: the isocyanate (part A) reacts with water vapour and can generate bubbles or alter the cure.
Colouring and finishes
PT Flex 50 can be coloured with PolyColor Dyes, Feroca's special pigments for polyurethane. Add the pigment to part B before mixing with part A to ensure even dispersion. Do not exceed 3–5% of the total mix weight so as not to compromise the mechanical properties.
Frequently asked questions
How much temperature can this polyurethane rubber withstand?
PT Flex 50 should not exceed 60 °C in service. Above that temperature the mechanical properties degrade and the part can deform permanently. For applications with higher thermal exposure, check other references in the Feroca catalogue.
What is the difference between PT Flex 50 and other hardnesses in the range?
PT Flex 50 is the most flexible and elastic reference in the range Feroca offers alongside PT Flex 60, 70 and 85, with 200% elongation at break, higher than the rest. If you need more mechanical strength and hardness, consider PT Flex 60 or higher grades in the range. If you're after even more softness, there's also PT Flex 20.
Do I need a release agent to work with this type of rubber?
Yes, it's always recommended to use a suitable release agent for polyurethane on the mould before casting. Polyurethane tends to stick to porous surfaces and some plastics. The release agent ensures clean demoulding and extends the mould's service life.
Can I use pigments with this rubber?
Yes. PolyColor Dyes and pigment pastes formulated for polyurethane resins are fully compatible with PT Flex 50. Add the pigment to part B before mixing with part A for an even dispersion.
Is it suitable for gaskets and sealing parts?
Yes, its high elongation at break (200%) and moderate Shore A50 hardness make it very suitable for gaskets and parts that must deform repeatedly without cracking. For parts that also need higher abrasion resistance, consider a higher grade in the PT Flex range.
Can it be laminated with carbon fibre or fibreglass?
It's not recommended. Reinforcement fabrics such as carbon fibre or fibreglass are designed to work with rigid materials. In a flexible rubber like PT Flex 50 they provide no structural advantage and adhesion between the fabric and the flexible matrix is problematic. For reinforced rigid parts, check rigid polyurethane resins such as Feropur PR55+E55.
What should I do if the material has gelled inside the container?
Gelling of part A (isocyanate) occurs from exposure to ambient humidity. Gelled material cannot be used: the cure will be incomplete and the mechanical properties won't be correct. To avoid this, always seal containers immediately after each use and store them in a dry place. If the product shows lumps or has noticeably thickened, discard it.
How does this rubber differ from a rigid polyurethane resin?
PT Flex 50 is an elastomer: once cured it's very flexible, stretches easily and recovers after deformation. A rigid resin such as Feropur PR55+E55 offers structural rigidity, higher hardness and is suitable for parts that must not deform. The choice depends on whether the final part needs flexibility or rigidity.
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