A method for the production of a paper web having a cf - layer for pressure sensitive carbonless paper

摘要

The characteristic features in prodn. of a CF (coated front) paper web for use in pressure sensitive carbon paper by application of an organic colour acceptor are that (i) the paper is fully bulk sized, and (ii) is then passed through the gap between rollers (2,2') at minimal pressure such that a volumetrically dosed colour material (4) obtd. using a profiled doctor (3') is applied as a CF layer (4') on one side of the web (1) and a volumetrically dosed aq. soln. (5) obtd. using a profiled doctor (3) is applied to the other side. Pref. the CF-coating material (4) has more than 40 wt.% solids content and contains in addn. to the acceptor, up to 90 wt.% (based on total solids) of CaCO3, kaolin, BaSO4, talc, chlorite, pptd. silicate and/or Al(OH)3 as non-colour active pigment. ADVANTAGE - The process can be effected using a 'speed sizer' (DE3417487), which enables use of small amts. of colour acceptor material to yield a thin, uniform complete coverage which results in intense reaction between the acceptor and colour precursor. The dry wts. of CF layer and acceptor applied are 3-6 and 0.2-2 g/m2 respectively (claimed). Further, simultaneous application of CF-layer (4) and back coating (5) (pref. starch) gives faster prodn.