Resitol

B-Stage resin. (resitol). A thermosetting phe-nolformaldehyde-type resin that has been thermally reactive beyond the A stage so that the product has only partial solubility in common solvents (alcohols, ketones) and is not fully fusible even at 150-180C. The B stage resin has limited commercial use. 

In the following reactions, both ether and methylene bridges are formed. These precondensates are water-soluble and can only be entirely cross-linked at high temperatures. The Baekeland stages resole (Bakelite A), resitole (Bakelite B), and resite (Balelite C) apply analogously here... 

B-stage—An intermediate stage in the reaction of certain thermosetting resins in which the material softens when heated to a rubbery state and swells when in contact with certain liquids, hut may not entirely fuse or dissolve in some of the solvents which will dissolve resins in the A-stage. The resin in an uncured thermosetting adhesive is usually in this stage. Sometimes referred to as Resitol. 

Resite n. A phenol-formaldehyde resin in the final state of the curing process. In this stage it is insoluble in alcohol and acetone, and infusible. Alternate term for C-stage. See C-stage also called resitol and resol. 

It may be mentioned here that it is common practice to refer to resols as stage resins and to the final network polymers as resits or C stage resins intermediate materials are called resitols oxB stage resins,... 

Resitols are formed (under alkaline catalysis) by the reaction... 

The novolac resins are usually applied as solid adhesives incorporating some phenol and formaldehyde (from hexamethylene tetramine) to cross-link the prepolymer when heat is applied. Resitol resins are applied as a dispersion in dilute aqueous NaOH with fillers, surfactants, and extenders. 

Resols on further heating change into resitols, a three-dimensional network polymer of low crosslink density as... 

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