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|Appearance:||Light Yellow Transparent Pellets||Package:||25kg Bag|
|Melting Point:||90-93℃||Monomers:||Phenol And Formaldhyde|
Novolac Phenolic resin (two-step) is produced by condensing phenol with an insufficient amount of formaldehyde to complete the reaction in the presence of an acid catalyst. This produces a thermoplastic resin. To cure this resin, a hardening agent is used, HMTA (or hexa). Under heat and pressure, it yields ammonia and formaldehyde as methylene groups to cure the resin, hence the term “two-step,” because of the two formaldehyde additions. A novolak phenolic resin has an infinite shelf life under normal storage conditions.Cured phenolic resin provides the rigidity necessary to maintain structural integrity and dimensional stability even under severe conditions.
Novolac Phenolic Resin P1291 is recommended for Foundry Resin Coated Sands.Manufacturers using the shell molding process experience excellent dimensional accuracy, surface smoothness and high production rates using phenolic resin coated foundry sands. The shell molding process involves first creating mold cavities and cores by shaping sand coated with phenolic resin over a not metal form. Removed from the form and assembled, the mold and cores create the "negative" shape of the desired metal form. Hot metal is poured into the resin-sand mold and allowed to cool. Once hard, the excess resin-sand material is broken away revealing the metal part. Some recover the broken away sand for reuse. The careful selection of sand type, resin characteristics and coating method results in the desired mold and core properties such as strength, rigidity, flexibility, surface finish, part release and applicability to reuse.
|Curing time @150°C||50-70s||GB/T24411-2009|
the package is paper-plastics bag in 25KGS each one
The storage life of this product is several months in a cool and dry place in original closed bags