A phenolic adhesive formanufacturing water-resistant plywood without predrying
A highly reactive phenolic resin of the rezol type formanufacturing water-resistant plywood has been prepared by precondensation ofphenol with formaldehyde to a lowmolecular-weight resin with a high content ofhydroxymethyl groups and by a further condensation of the thus-prepared resin ata higher temperature to the attainment of the desired viscosity. The optimum parametersof this condensation have been established, its criteria being: viscosity inthe range of 20–40 Pa . s and free phenol and formaldehyde contentin the resin below 1 per cent by weight. Basing on the thus-prepared resin, anadhesive composition with the addition of a vegetable tanning agent has been elaboratedand used in the manufacture of water-resistant plywoody by a method without predrying.
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