Patent GB-584142-A (GB)
Title: Improvements relating to moistureproofing coating compositions
IPC: D21H17/60
Filed: 1944-08-26
Abstract: A hot-melt moisture-proof coating composition comprises 10 to 35 per cent ethyl cellulose, 20 to 28 per cent of a plasticiser, 16 to 28 per cent of a waxy moisture-proofing agent and 12 to 52 per cent of a non-heat-convertible resin, the amount of ethyl cellulose and moisture-proofing agent being not less than 50 per cent and 80 per cent respectively by weight of the amount of plasticiser.  The non-heat-convertible resin may be a natural gum or resin, a modified natural gum or resin, a synthetic resin or a mixture thereof, examples of which are dammar gum, rosin, the glycerol ester of rosin, the pentaerythritol ester of rosin, the phenolic modified pentaerythritol ester of rosin, hydrogeneted rosin and its derivatives such as the glycerol ester of hydrogenated rosin, polymerized rosin and its derivatives such as the ethylene glycol ester of polymerized rosin, the non-heat-convertible coumarone and indenecoumarone resins, polybasic acid-polyhydric alcohol resins such as the rosin modified glycerol maleates, phenol-aldehyde type resins and chlorinated diphenyl resins.  Specified moisture-proofing agents are waxes and wax-like materials, singly or in admixture such as paraffin wax, microcrystalline waxes, ceresin, japan wax, carnauba wax, candelilla wax, beeswax, chlorinated naphthalene and other synthetic waxes.  Suitable plasticisers employed singly or in admixture are chlorinated diphenyl, dibutyl phthalate, methyl cyclohexanol phthalate, dicyclohexyl phthalate, cyclohexanol phthalate, ethyl abietate, ethylphthalyl-ethyl glycolate, dehydrated castor oil-rosin complex and tricresyl phosphate.  The composition which is highly moisture-proof and heat-sealable may be applied to paper, cardboard, canvas, cloth, gauze and other fabrics, and aluminium and other metal foils, and may be used as a laminating agent to secure together two or more sheets of fibrous or other materials.  The composition may be applied to the material to be coated by dipping followed by nipping, the knife coating method, casting, extrusion or rotogravure methods, and the operation is effected at elevated temperatures.  In preparing the composition, the ethyl cellulose, preferably lightly damped with a volatile non-solvent, e.g. normal heptane, as described in Specification 582,029, is dissolved in the heated plasticiser or in a heated mixture of the plasticiser and resin and the paraffin wax added last of all unless it is compatible with the ethyl cellulose.  Examples are given in which (1) a composition comprising 40 per cent coumarone resin, 21.6 per cent methyl cyclohexanol phthalate, 17 per cent ethyl cellulose and 21.4 per cent paraffin wax is prepared and applied on a roll coating machine at 135 DEG  C. to a manilla paper.  (2) A composition comprising 31 per cent rosin modified glycerol-maleate resin, 21.6 per cent methyl cyclohexanol phthalate, 25 per cent ethyl cellulose and 22.4 per cent paraffin wax is prepared and applied to cotton cloth at 165 DEG  C. by dipping and nipping.  (3) A composition comprising dammar resin, liquid chlorinated diphenyl, ethyl cellulose and paraffin wax is applied at 160 DEG  C. on a roll coating machine to a thin cartridge board and a similar uncoated board is applied at 170 DEG  C. to the coated board to form a laminated structure.  (4) A composition comprising the same constituents as those of example (2), but in different proportions is applied at 185 DEG  C. to one side of a rag paper by means of a heated roller immersed and rotating in the melt.  (5) The composition of example (4) is applied to a fully bleached and glazed glassine paper.