Patent GB-1235695-A (GB)
Title: Manufacturing process for selfcopying papers, and papers produced according to such manufacturing process
IPC: B41M5/10
Filed: 1968-05-24
Abstract: 1,235,695. Pressure-sensitive copying paper. SELF COPY INTERNATIONAL. 24 May, 1968 [27 May, 1967], No. 24898/68. Heading D2B. [Also in Divisions C3 and C4] The donor layer of self-copying paper is prepared by (i) mixing (a) a colloidal aqueous suspension of pigment or covering substances and fillers or both, (b) a colloidal aqueous solution of water-soluble film-forming macromolecular compounds that can be irreversibly precipitated, and (c) an aqueous waxy emulsion, and (ii) progressively removing the water to obtain a heterogeneous but coherent film containing the pigments. The donor layer may comprise two layers of which the outer serves to mask the inner, both layers preferably being made by the method of the invention. The suspension (a) preferably is stabilized by a surface-active agent. Precipitation in step (ii) may be assisted by an electrolyte, by an acid or a base, by heat or by a dehydrating agent. Secondary fixing agents such as formaldehyde or boric acid and softening agents such as glycerine or polyglycols may also be added. These donor layers may be applied to paper during a final stage of its manufacture. Compositions used in the Examples comprise, in addition to water: (Al) carbon black, polyoxyethylene sorbitan monooleate, calcined kaolin, silica and titanium oxide; (A2) carbon black, polyoxyethylene sorbitan monolaurate, calcined kaolin, potassium aluminium silicate and zinc sulphide-barium sulphate; (A3) carbon black, polyoxyethylene lauryl alcohol, blown talc, zinc oxide and precipitated calcium carbonate; (A4) carbon black, sorbitan monooleate, precipitated alumina, bentonite and magnesium silicate; (A5) carbon black, polyoxyethylene ether of monylphenol, precipitated alumina, diatomite and zinc sulphidebarium sulphate; (A6) polyoxyethylene sorbitan monolaurate, bentonite, zinc oxide and titanium oxide; (A7) sorbitan monooleate, calcined kaolin, zinc sulphide-barium sulphate and titanium oxide; (A8) polyoxyethylene ether of nonylphenol, zinc sulphide-barium sulphate, zinc oxide, precipitated calcium carbonate and titanium oxide; (Bl) gelatine and ammonia; (B2) lactic casein; (B3) sodium alginate; (B5) oxidised potato fecula; (B7) chlorinated rice starch; (B8) urea-formaldehyde; (C1) paraffin wax and petrolatum; (C2) petrolatum; (C3) microcrystalline wax; (C4) paraffin wax and vinyl resin; (C6 to C8 montan wax; (I) compositions of Examples Al, B1 and Cl mixed with sulphosalicylic acid and sodium sulphate; (II) compositions of Examples A2, B2 and C2 mixed with ethyl alcohol, ammonium sulphate and glycerine; (III) compositions of Examples A3, B3 and C4 mixed with acetic acid and barium chloride; (IV) compositions of Examples A5, B5 and C3 mixed with trichloracetic acid and ammonium sulphate; (V) compositions of Examples A6, B1 and C6 mixed with ethyl alcohol, pentadigalloylglucose and polyglycol; (VI) compositions of Examples A7, B7 and C7 mixed with acetone and potassium nitrate; and (VII) compositions of Examples A8, B8 and C8 mixed with ethyl alcohol and formaldehyde. The compositions of Examples V to VII are for masking layers.