Patent GB-427724-A (GB)
Title: Improvements in or relating to protective coverings
IPC: C09D101/12
Filed: 1933-08-24
Abstract: Articles, such as insulated conductors, particularly those having a rubber insulation are protected by a plurality of flexible coatings each containing an organic derivative of cellulose with at least 50 per cent of plasticizer or mixture of plasticizers, the basic coating being soft and containing a high proportion of a plasticizer or mixture of plasticizers of high solvent power, and the top coating being harder and containing a high proportion of a plasticizer or mixture of plasticizers of high compatibility but limited solvent power.  Examples of suitable plasticizers for the basic coating are aromatic sulphonamides and tartrate esters as specified in Specification 362,481, [Group III], and triacetin, and these plasticizers may be mixed with others of low compatibility with the cellulose derivative such as triphenyl phosphate, tricresyl phosphate, diphenylol propane, and diethyl phthalate.  Suitable plasticizers for the top coating are triphenylacetin, glycerine-diacetate, mono-acetyl-salicytate, the phenoxyacetines, mixed esters of glycol or glycerol with acetic and phenyl acetic or phenoxyacetic acids, and sulphonamides or tartrates "loaded" with aromatic, hydroaromatic or high aliphatic radicles, e.g. dibenzyl tartrate, di-iso-amyl phthalate, b -phenoxyethyl phthalate or benzyl ethyl phthalate.  Similarly suitable plasticizers for the top coat may be made by increasing the compatibility of triaryl phosphates by the introduction of oxy- or ketonic groups as in tri-resorcinol phosphate.  The compositions may be moulded on to the article being protected, or may be dissolved in suitable solvents such as acetone, methyl acetate, alcohol, benzene, methyl-ethyl ketone, ethylene dichloride or mixtures thereof, or dioxane, ethyl lactate, or ethyl lactate with methyl glycol or ethyl glycol mono-acetate.  The bases of the coating may be any of the common organic esters or ethers with or without polyvinyl compounds, and natural, semi-synthetic or synthetic resins.  The coatings may be applied by brushing, spraying or bath treatment and, in the case of insulated cables, may be applied to tapes, ribbons or films to be wound round the insulating material, or to fabrics with which the insulating material is covered.  If the tape or other material contains a cellulose derivative it should be a different one from that employed in the coating composition applied thereto.  Both coating-compositions may be applied to the same tape or other material or they may be applied to separate materials wound one on top of the other.  The layers of impregnated material may be caused to adhere together by the application of heat or of solvents in liquid or vapour form. Examples of suitable compositions which may be applied in a solvent medium consisting of 400 parts of acetone, 160--180 parts of alcohol, and 240--220 parts of benzene per 100 parts of cellulose derivative are in the case of top coatings, cellulose acetate 100 parts, with triphenyl acetin 160, or 230 parts, or triphenyl acetin 120 parts and isomeric xylene mono-methyl sulphonamides 15--30 parts, or triphenyl acetin 140 parts and dibutyl tartrate 45 parts, or ethyl cellulose 100 parts, with 85 parts of triphenyl acetin, or employing a plasticizer of high solvent power with one of low compatibility a suitable composition is cellulose acetate 100 parts, isomeric xylene mono-methyl sulphonamides 130 parts, and dibutyl phthalate 30 parts. Glyakol or diglycerine tetracetate may replace the sulphonamides. Suitable basic coatings are cellulose acetate 100 parts with triphenyl acetin 50 or 60 parts and isomeric xylene monomethyl sulphonamides 90 or 60 parts, or cellulose acetate 100 parts with 30 parts of diphenylol propane formaldehyde resin, 120 parts of dibutyl tartrate, and 20 parts of triphenyl phosphate, or ethyl cellulose 100 parts with 60 parts of castor oil, or 40 parts of castor oil and 20 parts of dibutyl phthalate.  Specification 427,621 also is referred to.ALSO:Articles, such as insulated conductors, particularly those having a rubber insulation are protected by a plurality of flexible coatings each containing an organic derivative of cellulose with at least 50 per cent of plasticizer or mixture of plasticizers, the basic coating being soft and containing a high proportion of a plasticizer or mixture of plasticizers of high solvent power, and the top coating being harder and containing a high proportion of a plasticizer or mixture of plasticizers of high compatibility but limited solvent power.  Examples of suitable plasticizers for the basic coating are aromatic sulphonamides and tartrate esters as specified in Specification 362,481, and triacetin, and these plasticizers may be mixed with others of low compatibility with the cellulose derivative such as triphenyl phosphate, tricresyl phosphate, diphenylol propane, and diethyl phthalate.  Suitable plasticizers for the top coating are triphenylacetin, glycerine-diacetate, mono-acetylsalicylate, the phenoxyacetins, mixed esters of glycol or glycerol with acetic and phenyl acetic or phenoxyacetic acids, and sulphonamides or tartrates "loaded" with aromatic, hydroaromatic or high aliphatic radicles, e.g. dibenzyl tartrate, di-iso amyl phthalate, b -phenoxyethyl phthalate or benzyl ethyl phthalate.  Similarly suitable plasticizers for the top coat may be made by increasing the compatibility of triaryl phosphates by the introduction of oxy or ketonic groups as in tri-resorcinol phosphate.  The compositions may be moulded on to the article being protected, or may be dissolved in suitable solvents such as acetone, methyl acetate, alcohol, benzene, methyl-ethyl ketone, ethylene dichloride or mixtures thereof, or dioxane, ethyl lactate, or ethyl lactate with methyl glycol or ethyl glycol mono-acetate. The bases of the coating may be any of the common organic esters or ethers with or without polyvinyl compounds, and natural, semi-synthetic or synthetic resins.  The coatings may be applied by brushing, spraying or bath treatment, and in the case of insulated cables, may be applied to tapes, ribbons or films to be wound round the insulating material, or to fabrics with which the insulating material is covered.  If the tape or other material contain a cellulose derivative, it should be a different one from that employed in the coating composition applied thereto.  Both coating-compositions may be applied to the same tape or other material or they may be applied to separate materials would one on top of the other.  The layers of impregnated material may be caused to adhere together by the application of heat or of solvents in liquid or vapour form.  Examples of suitable compositions which may be applied in a solvent medium consisting of 400 parts of acetone, 160--180 parts of alcohol, and 240--220 parts of benzene per 100 parts of cellulose derivative, are in the case of top coatings, cellulose acetate 100 parts, with triphenyl acetin 160, or 230 parts, or triphenyl acetin 120 parts and isomeric xylene mono-methyl sulphonamides 15--30 parts, or triphenyl acetin 140 parts and dibutyl tartrate 45 parts, or ethyl cellulose 100 parts, with 85 parts of triphenyl acetin, or employing a plasticizer of high solvent power with one of low compatibility a suitable composition is cellulose acetate 100 parts, isomeric xylene mono-methyl sulphonamides 130 parts, and dibutyl phthalate 30 parts.  Glyakol or diglycerine tetra-acetate may replace the sulphonamides.  Suitable basic coatings are cellulose acetate 100 parts with triphenyl acetin 50 or 60 parts and isomeric xylene monomethyl sulphonamides 90 or 60 parts, or cellulose acetate 100 parts with 30 parts of diphenylol propane formaldehyde resin, 120 parts of dibutyl tartrate, and 20 parts of triphenyl phosphate, or ethyl cellulose 100 parts with 60 parts of castor oil, or 40 parts of castor oil and 20 parts of dibutyl phthalate.  Specification 427,621, [Group IV], also is referred to.