VERSTAERKTE GIPSPLATTEN.

摘要

Reinforced plaster boards (I) are mfd. by mixing technical or pure rehydratable gypsum binder, pref. CaSO4.1/2H2O (II), with water, and reinforcing substance as required (pref. cellulose particles) (III), and pressing; the novelty is that polyisocyanates (IV) are added to the mixt. or applied to the surface of the prepd. board. (I) are claimed as such, in which the polyurea formed from (IV) is homogeneously distributed over the cross-section of the board or conc. in the edge zones. (IV) is a polymethylene- polyphenylpolyisocyanate, pref. modified to make it water-emulsifiable; amt. of (IV) is 1-10 wt.% w.r.t. (II) (III) (dry); (III) is pref. wood chips 1-10mm long; wt. ratio (III):(II) is from 0.25:1 to 0.35:1; pref., boards are modified with polyurea only in an edge zone by application of (IV) to the prepd, board surface.