Wood prods. mfr. esp. chipboard, with improved strength - by addn. of anthraquinone or anthraquinone mono:sulphonate before, during or after gluing with alkaline phenol] formaldehyde] resin

Prodn. from comminuted wood prods. (II) with alkaline PF resin binders (III); comprises adding anthraquinone or anthraquinone monosulphonate (IV) to (II) before during or after glueing with (III). Pref. amt. of (IV) is 0.01-5 (0.01-2) wt.% w.r.t. (II); (III) contains 3-15% alkali (w.r.t. a 50% glue bath), and is opt. modified with resorcinol, tannins or sulphite liq.; (IV) is only added to the wood chips in middle- or outer-layer of a chipboard which is bonded right through with (III); in multilayer boards in which the layers are bonded with different binders, (IV) is added to the layers bonded with (III); (IV) is added to the wood chips, or to the resin, before, during or after condensn. of phenol with formaldehyde. USE/ADVANTAGE - Addn. of (IV) gives (I) with increased strength and reduced thickness swell, without increasing binder- or alkali-content of the resin.