Scarcely flammable fibrous material prodn. - e.g. paper, cardboard, paperboard, fibreboard, with addn. of boron mineral and acidification

摘要

In the prodn. of fibrous material, e.g. paper, cardboard, paperboard and fibreboard, from a (vegetable) fibre mat, 3 stages are used (conversion of the wood and other raw materials to half stuff, conversion of this to whole stuff and prodn. of the final fibre mat on endless or round wire machines). Conversion to the whole stuff includes milling the fibres to pulp and addn. of finishing agents. The novel feature is that B minerals (I), e.g. boracite, borax, colemanite, kernite-pandermite, rasorite or ulexite, in finely ground form, are mixed with the pulp, then mineral acid, esp. H2SO4 (96%) or phosphoric acid is added, pref. in the stoichiometric amt. needed for boric acid formation from (I). The pulp is then ripened for ca. an hour before conversion to the end prod. Very good fire retardancy is imparted with little increase cost of the end prod. Ca sulphate is formed in the conversion of (I), which imparts very high strength.