Payment & Shipping Terms:
|Appearance:||Light Yellow Powder||Package:||25kg Bag|
|Melting Point:||98-105℃||Gel Time:||80-100 S @150℃|
|Flow:||50-70 Mm @ 125℃||Application:||Grinding Wheels|
A novolak 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.
Bonded abrasives like grinding wheels are comprised of abrasive particles embedded in a bonding matrix. While the grit used may be from a wide variety of minerals and abrasive particles, phenolic resin is the matrix binder of choice. Achieving the optimal combination of resistance to burst or fracture strength, flexibility and porosity, coupled to the manufacturing method, requires optimization of the binding resin to the specific application of the wheel in question. Modification of the blend of phenolic novolac powder, hexa, and liquid resol resin is usually needed to achieve such optimization. For increased strength, fiberglass reinforcement inlays are used. These inlays are themselves typically saturated with a special liquid phenolic resin.
|Curing time @150°C||90-110s||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