Buenos días cofrades,
He estado leyendo un hilo hace un momento en el que se hablaba de la sika 292 para sellar la unión casco-orza así que aprovechando que "lo mío" está de actualidad subo mi propio hilo.
He escrito a Sikaflex, de momento sin respuesta -igual que en La Taberna
Solamente en un foro británico he encontrado que se podría "forzar" el curado con amoníaco y que si con ello no cura es que la Sika está definitivamente estropeada:
"Try spraying or painting a small section you've applied already, or on some of your batch on a solid surface, with an ammonia solution. The cure (X-linking) mechanism is normally free isocyanate + water ==> polyurea ( the "polyurethane" part of the final product is already pre polymerised in the material in the tube). The Isocyanate + water reaction in itself is pretty slow and needs catalyst to be present to have any decent rate.. The isocyanate + primary amine reaction is very fast indeed and does not need catalyst, ammonia is even more reactive with isocyanates than primary amines.
If ammonia does not result in any cure, there are no free isocyanates in there to react with water and the material will never "set"
If ammonia does result in cure, there are free isocyanates available and it will cure on reaction with absorbed water, albeit very slowly for this lot it seems. Probably due to low catalyst level, but increased acidity also retards the cure. One of the oldest used catalysts is "Dabco" ( TEDA, triethylene diamine) which used in a solution in ethylene glycol, propylene glycol or 1.4. butane diol. A GRP resin supplier might be able to supply it. Applying such a material to the surface will allow diffusion of the catalyst into the sealant and bring on cure if there is any isocyanate to react up.
Truly, the forum is an impressive fount of knowledge at times!
Pete"
¿Alguna opinión experta?
Gracias.