Patent GB-584217-A (GB)
Title: Improvements in or relating to the manufacture of non-fibrous films of water-sensitive, organic film-forming material
IPC: C08J7/052
Filed: 1944-12-15
Abstract: Water-sensitive organic films, e.g. films of regenerated cellulose, cellulose ethers and polyvinyl alcohol, are impregnated with 30 to 60 per cent of a softener, and an insoluble artificial resin of one of the classes specified below which is capable of being formed in situ by heating to 60-90 DEG  C.  The classes of resins which may be used are phenol-formaldehyde resins, dimethylol urea resins, dimethylol urea ether resins, melamine-formaldehyde resins, aminotriazine-aldehyde resins, aldehyde condensation products (such as casein-formaldehyde, guanidine-formaldehyde, aliphatic and aryl ketones with formaldehyde, urethane-aldehyde and cyanamide-aldehyde), furfuramide resins and furfural reaction products with amines, phenols and ketones, thiocyanate resins, thio-urea resins, acrolein-urea resins and urea-aldehyde modified phthalic acid glycerine resins.  The amount of artificial resin in the finished film is preferably from 1-10 per cent.  Suitable softeners for use in the process are glycerine, glycols, amines or amino-alcohols and salts thereof, hydroxy-amides, ether-alcohols, sulphones, sulphoxides and urea.  The film may be impregnated by passing it through an aqueous bath containing the softener and the incompletely condensed or polymerized water-soluble product and thereafter drying the film at 60 DEG  to 90 DEG  C.; or by first passing it through the aqueous bath containing the softener and then spraying it with a solution of the incompletely condensed or polymerized product and finally drying at 60 DEG  to 90 DEG  C.; or by incorporating the incompletely condensed or polymerized product into the solution from which the film is cast and thereafter passing the film through an aqueous bath containing the softener and finally drying by heating as before. Condensing agents such as maleic acid and paratoluene sulphonic acid may be used in conjunction with the incompletely condensed products. The products of the invention may be moisture-proofed by coating in known manner.  Examples are given of the preparation of films comprising (1) 43.3 per cent glycerine and 5.3 per cent dimethylol urea resin; (2) 45 per cent glycerine and 2 per cent of phenol-formaldehyde resin; (3) 45 per cent glycerine and 7 per cent monomethyl ether of dimethylol urea; (4) 43.7 per cent glycerine and 5 per cent melamine-formaldehyde resin; (5) as in (1), but the film is coated with a composition containing urea-formaldehyde resin and nitrocellulose; (6) as in (1), but the film is coated with a composition containing nitrocellulose, paraffin wax, dammar and ethylene glycol "Heet-Rex" (3-isopropyl-6-methyl-3,6-endoethylene-delta-4-tetrahydrophthalic anhydride); (7) as in (1), but the film is then coated firstly with the composition of (5) and secondly with the composition of (6); (8) as in (1), but the film is coated with a composition containing nitrocellulose, urea-formaldehyde monomeric alcohol resin, "Beckacite" (R.T.M.) (ester gum-rosin and maleic acid glyceride complex) and paraffin wax; (9) as in (4), but the film is coated with the composition of (6); (10) urea-formaldehyde resin and glycerine, and the film is then coated as in (6). Specification 211,446, [Class 2 (ii)], is referred to.