Patent GB-479257-A (GB)
Title: Improvements in or relating to impregnated material
IPC: A43B23/08
Filed: 1937-04-30
Abstract: <PICT:0479257/IV/1> Stiffening-material is made by impregnating sheet material, e.g. fabric or felt, with a solution of a plastic material in a volatile solvent, and then, in absence of air, removing the solvent in vapour form by means of an inert vapour such as steam, condensing the solvent and inert vapour together and removing the solvent from the condensate, e.g. by gravity or fractional distillation.  The plastic material may be a natural or artificial resin, e.g. polyvinyl acetate, acetaldehyde modified vinyl acetate or phenol-formaldehyde resin; or a cellulose derivative, e.g. p cellulose nitrate, acetate propionate, formate or butyrate, ethyl, methyl or benzyl cellulose or cellulose aceto-butyrate; or a mixture of these.  The volatile solvent preferably has a boiling point lower than that of the evaporating agent and may be acetone, methyl acetone, methyl or ethyl alcohol, methyl acetate, ethylene glycol methyl ether, chloroform, ethylene dichloride or mixtures. The solution may contain plasticizers such as p-ethyl toluenesulphonamide, dimethyl phthalate, dibutyl tartrate, di-(ethoxy ethyl) phthalate, the phthalate of diethylene glycol monoethyl ether, triethyl-glycol phosphate, tricresyl phosphate, ethylglycol-dicresyl phosphate or camphor.  Fabric from a roll 26 passes by guide rolls 12 through the impregnating composition in a jacketed tank 22, between an adjustable scraper 27 and backing roll 28, through a slit 24 into a chamber 23.  Steam is injected on to both sides of the fabric from jets 25 whereby the solvent is evaporated and the plastic material precipitated in the fabric, which is then led over guide rolls 14 through a seal 30, between squeeze rolls 31 to a drying roll 32.  The mixture of steam and solvent is withdrawn by a conduit 15, condensed in a condenser 35 and received in a tank 36, whence it passes to a fractionating still 39.  Recovered solvent from a condenser 42 is collected in a tank 44, whence it is withdrawn as desired and mixed with plastic material in a tank 46.  The apparatus is freed from air before starting the process by turning on the steam jets 25 or by filling the apparatus with nitrogen or carbon dioxide.ALSO:<PICT:0479257/III/1> Stiffening-material is made by impregnating sheet material, e.g. fabric, felt, leather, or paper with a solution of a plastic material in a volatile solvent, and then, in absence of air, removing the solvent in vapour form by means of an inert vapour such as steam, condensing the solvent and inert vapour together and removing the solvent from the condensate, e.g. by gravity or fractional distillation.  The plastic material may be a natural or artificial resin, e.g. polyvinyl acetate, acetaldehyde modified vinyl acetate or phenol-formaldehyde resin; or a cellulose derivative, e.g. cellulose nitrate, acetate, propionate, formate or butyrate; ethyl, methyl or benzyl cellulose or cellulose aceto-butyrate; or a mixture of these.  The volatile solvent preferably has a boiling point lower than that of the evaporating agent and may be acetone, methyl acetone, methyl or ethyl alcohol, methyl acetate, ethylene glycol methyl ether, chloroform, ethylene dichloride or mixtures.  The solution may contain plasticizers such as p-ethyl toluenesulphonamide, dimethyl phthalate, dibutyl tartrate, di - (ethoxyethyl) phthalate, the phthalate of diethyleneglycol mono - ethyl ether, triethyl - glycol phosphate, tricresyl phosphate, ethylglycol-dicresyl phosphate or camphor.  Fabric from a roll 26 passes by guide rolls 12 through the impregnating composition in a jacketed tank 22, between an adjustable scraper 27 and backing roll 28, through a slit 24 into a chamber 23.  Steam is injected on to both sides of the fabric from jets 25 whereby the solvent is evaporated and the plastic material precipitated in the fabric, which is then led over guide rolls 14 through a seal 30, between squeeze rolls 31 to a drying roll 32.  The mixture of steam and solvent is withdrawn by a conduit 15, condensed in a condenser 35 and received in a tank 36, whence it passes to a fractionating still 39. Recovered solvent from a condenser 42 is collected in a tank 44, whence it is withdrawn as desired and mixed with plastic material in a tank 46.  The apparatus is freed from air before starting the process by turning on the steam jets 25 or by filling the apparatus with nitrogen or carbon dioxide.