Fluoran UR · calcium hydroxide
Acidic species develop during fluoroelastomer curing. Fluoran UR neutralises them, with the consistency of a high-purity product.
Why it is needed
During the curing of fluoroelastomers, acidic species develop which, if left unmanaged, compromise process stability and the properties of the finished part. The acid acceptor — or acid scavenger — has the task of neutralising them.
It is therefore an essential component of the FKM compound: without an adequate acid acceptor, vulcanisation does not proceed in a controlled and repeatable way.
Fluoran UR
The defining advantage of Fluoran UR is its non-hygroscopic nature. Standard calcium hydroxide attracts moisture from the environment and undergoes degradation; thanks to its hydrophobic coating, Fluoran UR remains stable over time even in humid environments.
For an acid acceptor this means consistent effectiveness: the product used after months in storage behaves like the one that has just arrived. The declared shelf life is 24 months.
No particles above 80 μm (0%), only 0.5% above 43 μm: optimal reactivity and uniform dispersion in the compound.
The data
Fluoran UR has a high active content and minimal impurities. For an acid acceptor, purity translates directly into performance: more active content means greater neutralising capacity at the same dosage, and fewer impurities means fewer variables interfering with curing.
The practical result is a consistent curing rate and a positive contribution to the thermal stability and mechanical integrity of the vulcanisate.
FAQ
It is an additive that neutralises the acidic species released during the curing of fluoroelastomers, which is why it is also called an acid scavenger. Without this neutralisation, vulcanisation does not proceed in a controlled and repeatable way and the properties of the part suffer. De Grandi produces Fluoran UR, a high-purity coated calcium hydroxide.
Because it is non-hygroscopic. Standard calcium hydroxide attracts moisture from the environment and degrades, losing effectiveness; thanks to its hydrophobic coating, Fluoran UR remains stable over time even in humid environments, with a declared shelf life of 24 months. It also offers high purity and an ultrafine particle size.
The particle profile is strictly controlled: 0% of particles above 80 microns and only 0.5% above 43 microns. This fineness ensures optimal reactivity and uniform dispersion of the acid acceptor in the FKM compound.
Yes, and it is decisive. A high active content means greater neutralising capacity at the same dosage, while minimal impurities reduce the variables that can interfere with curing. Fluoran UR is formulated with this objective, and the result is consistent curing rates and better thermal stability of the vulcanisate.
Fluoran UR is supplied in 20 kg paper bags with an inner polyethylene bag and in 500 kg big bags, with a shelf life of 24 months. The non-hygroscopic nature of the product is what makes this storage life possible: an untreated calcium hydroxide would lose effectiveness far sooner on contact with ambient moisture.
De Grandi produces Fluoran UR at its plant in Tromello, in the province of Pavia, Italy. For enquiries, samples and technical documentation you can contact the company on +39 0382 868402 or at info@degrandisrl.it.
