Patent GB-559858-A (GB)
Title: Electrically insulated conductors in which the insulation comprises a high molecularweight polymer
IPC: H01B3/30
Filed: 1942-07-13
Abstract: 559,858. Electrical insulation. DU PONT DE NEMOURS & CO., E. I. July 13, 1942, No. 9699. Convention date, July 14, 1941. [Class 2 (iii)] [Also in Group XXXVI] Electrical insulation comprises a high molecular weight polymer formed by treating a low molecular weight linear polyester-amide with an organic polyisocyanate or polyisothiocyanate. The polyester-amides are prepared from suitable combinations of bifunctional materials such as diamines, glycols, dibasic acids, amino alcohols, amino acids, and hydroxy acids, for example from a dibasic acid, a diamine and a glycol, or from a dibasic acid and an amino alcohol. The ratio of amide linkages to ester linkages is preferably from 5-50 per cent. Suitable dibasic acids are carbonic, malonic, succinic, maleic, glutaric, suberic, azelaic, #-methyl adipic, hexahydroterephthalic, diphenic, p-phenylenediacetic, thiodibutyric, acetone-dicarboxylic, diglycollic, pimelic, undecanedioic, isophthalic, brassilic, 6-ketoundecanedioic, and 4-ketopimelic. Suitable glycols are diethylene glycol, triethylene glycol, hexamethylene glycol, decamethylene glycol, and NN<SP>1</SP> diethanolaniline. Suitable amino alcohols are ethanolamine, 3-aminopropanol, 4-aminobutanol, 6-aminohexanol, 10-aminodecanol, phydroxymethylbenzylamine, 4 - hydroxy - 4<SP>1</SP>- aminomethyldiphenyl, p-aminophenylethyl alcohol, 5 - amino - pentanol - 1, 6 - amino - 5 - methylhexanol - 1, 4(p-aminophenyl) cyclohexanol, hydroxyethoxyethoxyethylamine, and N - (# - aminoethyl) - N - (hydroxyhexyl) aniline. Suitable diamines are ethylenediamine, hexamethylene diamine, 3-methylhexamethylenediamine, decamethylene diamine and mphenylene diamine. Suitable hydroxy acids are 6 - hydroxycaproic, 10 - hydroxydecanoic, and 12 - hydroxystearic. Suitable aminocarboxylic acids are 6-aminononanoic, 11-aminoundecanoic, 12-aminostearic, and caprolactam. Amide or ester forming derivatives of these compounds may be employed, e.g. esters, amides, anhydrides, halides, lactams, N-formyl derivatives, carbamates, nitriles in the presence of water, cyanocarboxylic acids, cyanoamides, and cyclic imides. The wax-like low molecular weight linear polyester-amides are treated at 150‹C.- 250‹C. with up to 10 per cent., preferably 3-7 per cent. of their own weight of an organic polyisocyanate or polyisothiocyanate. Suitable materials are ethylenediisocyanate,trimethylene diisocyanate, tetramethylene diisocyanate, decamethylene diisocyanate; heptylidene diisocyanate, cycloalkylene diisocyanates, mphenylene diisocyanate, naphthalene diisocyanate, diphenyl - 4:4<SP>1</SP> - diisocyanate, xylene - 1, 4 - diisocyanate, 4 - 4<SP>1</SP> - diphenylene methane isocyanate, SCNCH 2 ,OCH 2 ,NCS and their sulphur analogues. The insulating compositions may contain various fillers and modifiers which may be incorporated in mill mixers or rubber rolls with or without the assistance of a volatile blending agent in solutions, or, if inert, may be mixed with the original reactants of the insulating material. Suitable fillers are wood flour, clay, whiting, vermiculite, mica, leather dust, asbestos, silica, cellulose derivatives, zinc oxide, carbon black, colouring lakes, azo pigments, prussian blue, chrome green, titanium oxide, iron oxide, lithol red, lithopone, zinc sulphide, iron blue, blanc fixe and phthalocyanines. Suitable modifying agents are dimethyl sebacate, polyethylene glycol, polyvinyl acetate, phenol-formaldehyde resins, ureaformaldehyde resins, oil-modified alkyd resins, rosin, hydrogenated rosin, ester gum, hydrogenated ester gum, shellac, gum kauri, copal, carnauba wax, diamylphthalate, dioctylphthalate, dilaurylphthalate, diethylene glycol dicresyl ether, ethyleneglycolmonobenzyl ether, stearic acid, oleic acid, sodium stearate, zinc stearate, aluminium stearate, dibutyl ammonium oleate, and dibutyl ammonium stearate. Suitable stabilizers against heat, light and outdoor exposure are hexamethylene bis-salicylamide, hydroquinone, aminophenols, o-hydroxymethoxyacetic acid, o-methoxyphenoxyacetic acid and o-phenylenediacetic acid. Conductors may be coated by passage through the molten insulating material or through a solution with subsequent evaporation of the solvent or by extrusion in a conventional wire coating machine or may be wrapped with ribbons cut from sheets prepared with the material. If desired the conductor may be coated with the initial low molecular weight polymer and the polyisocyanate and the reaction completed in situ. Successive coatings may be applied and coatings containing the insulating material of the present invention may be applied above or below coatings of materials such as neoprene, rubber, or plasticized polyvinyl chloride, or polyvinyl formal. The insulated conductors are particularly useful for articles to be exposed to oils, fats, hydrocarbons, e.g. in the food-handling, dairy, petroleum or chemical industries. The insulation is also particularly useful for refrigerator motors where contact with refrigerants such as sulphur dioxide or dichlorodifluoromethane is probable, for household appliances where wires are subject to much bending and rubbing. It may also be used for casings and separators in storage batteries, in condensers, and as coil insulation and slot lining of motors or generators. Examples describe (1) preparation of a polymer from adipic acid, ethylene glycol, and hexamethylene diammonium adipate and its treatment with hexamethylene diisocyanate, the incorporation of the resultant material into compositions with china clay alone, china clay with tricresyl phosphate, and china clay with chlorinated diphenyl and the application of the compositions to gauge 14 wire, and (2) preparation of a polymer from adipic acid, ethylene glycol and ethanolamine, its treatment with hexamethylene diisocyanate, dissolution of the resultant material in a mixture of equal parts of chloroform and methanol and the application of successive coatings of the material to No. 14 tinned copper wire. Specification 553,733 is referred to.