| 摘要 |
<p>A process for producing nonflammable laminated materials which includes the steps of impregnating a cellulose-containing material with an impregnating solution containing a phenolic-resol resin solution, at least one plasticizer for the resin and optionally flameproofing agents, subsequently drying the impregnated material to effect preliminary condensation of the resin and thereafter curing superimposed layers of the impregnated and preliminary condensed material by the application of heat and pressure. The phenol-resol resin solution used contains 50-80% by weight of an ammonia alkaline-condensed phenol-resol resin with a solids content of 65-80% by weight and with a molecular weight distribution determined by gel chromatography of: dimers 20-26%; tri- and tetramers 6-12%; penta- and oligomers 24-36%; expressed in percent per unit area and hexamethylenetetramine in amounts of 1-15% by weight based on the weight of the impregnating solution.</p> |
