Phenolic Resins for Wood Bonding

Phenol-formaldehyde resins are mostly used for wood bonding. According to Pizzi the best resins are characterized by the following [Pg.92]

Relatively low alkali content, generally about one-third to not more than one-half molar, based on phenolic hydroxyl. [Pg.92]

High methylol group content or free formaldehyde, or a matching catalyst which contains paraformaldehyde. [Pg.93]

B-stage characteristic of reliquefying briefly under heat and pressure to allow transfer and flow in the glue lines of a plywood panel. [Pg.93]

Higher thermal softening point than many other conventionally prepared resins. [Pg.93]

Since phenolic resins for wood bonding harden only thermally, postcuring during hot stacking is very important. In contrast to UF-bonded boards, PF-bonded boards should be stacked as hot as possible to guarantee a maximum postcuring effect. The... [Pg.895]

The use of phenolic resins for wood bonding has been reviewed by Pizzi, Dinwoodie, Kollmann and coworkers, " the U.S. Department of Agriculture, and Barth. Tapered double cantilever beam specimens have been recently used to test the effect of bondline thickness and cure time on the fracture energy of phenolic-wood adhesive joints. ... [Pg.93]

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