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A novolak resin (two-step) is produced by condensing phenol with an insufficient amount of formaldehyde to complete the reaction (ratios of formaldehyde to the phenol, F/P, are from 0.5 to 1) in the presence of an acid catalyst (sulfuric acid,oxalic acid, etc.). This produces a thermoplastic resin. To cure this resin, a hardening agent is used, HMTA (or hexa). Hexa is made from ammonia and formaldehyde.
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 condition.
Application
One of the most important applications of phenolic resins is the manufacture of phenolic molding compounds(PMC).PMC exhibits well balanced properties such as heat resistance, chemical resistance, dimensional stability, and creep resistance. They are widely applied in electrical, appliance, small engine, commutator,and automotive applications
Specification:
Properties | Value | Test standard |
Curing time @150°C | 60-9s | GB/T24411-2009 |
Flow Distance@125°C | 35-65mm | GB/T24411-2009 |
Free-phenol | 3.5-5% | GB/T30773-2014 |
Soften point | 96-106 | ZJHM-QESP-01-2015 |
Water content | 0.5-2.0% | GB/T2683-2008 |
Packing&Storage
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