Patent GB-1030026-A (GB)
Title: Polyamide-acid solutions and electrical insulation material prepared therefrom
IPC: C08G73/10
Filed: 1963-10-17
Abstract: A process for the production of an electrical insulating varnish containing one or more polyamide-carboxylic acids which can be converted to a polyimide by subsequent thermal or chemical treatment comprises reacting one or more diamines with one or more tetra-carboxylic acid dianhydrides in the presence of one or more non-aqueous, polar organic liquids which are insert to the reactants under the reaction conditions and which are solvents for at least one of the reactants under the reaction conditions and for the reaction product both at the reaction temperature and at room temperature, at a temperature below 60 DEG  C., at least one of said diamines having the formula <FORM:1030026/C3/1> or <FORM:1030026/C3/2> where Ar1, Ar2, Ar3, Ar4 an Ar5 are mono- or multinuclear aromatic residues, two or more of which may be the same, and X1, X2, X3 and X4 are carbon, nitrogen oxygen, silicon, phosphorus or sulphur atoms having at least two free valencies, two or more of which atoms may be the same. Specified diamines are p-diamino - diphenyl, 4: 41 - diaminodiphenyl propane, 4: 4-diaminodiphenyl methane, 4: 41-diaminodiphenyl ether, 4:41-diaminodiphenyl sulphone, 4:41-diaminodiphenyl sulphide, m-phenylene diamine, p-phenylene diamine, the bis-p-aminophenyl ethers of 4:41-dihydroxy-diphenyl, diphenylolpropane, diphenylol methane, diphenylol ether, diphenylol sulphone and hydraquinone, 3:31-diaminopentaphenyl-1:4-polyether, bis-(methyl-p-aminophenyl-amino)-4:41-diphenyl ether, bis-1:5-(p-aminophenyl-amino) - naphthalene, 41 - amino - 4 - (p-aminophenyl ether)-diphenyl methane, bis-(m-aminophenol ether) - 4:41 - bisphenol - A, bis - (1:5 - aminonaphthalene ether) - 4:41-bisphenol - A, bis - (1:5 - aminonaphthalene ether) - 1:5 - naphthalene, bis - [3:5 - dimethyl - 4 - aminophenyl thioether (1)] - p:p1 - diphenyl sulphide, bis - [4-aminophenyl-sulphonyl (1)]- p - phenyl, bis - [3 - aminophenyl - acetamino (1)] - m - phenyl, bis - (4 - aminophenyl - phenyl-phosphinyl (1)] - p - phenyl, bis - [3:5 - dimethyl - 4 - aminophenyl ether (1)] - p:p1-diphenylmethylphosphine oxide and bis-(4-aminophenyl - dimethyl silanyl] (1) - p - phenyl. Specified dianhydrides are pyromellitic, 2:3:6:7 - naphthalene tetracarboxylic, 3:31-4: 41 - diphenyl tetracarboxylic, 1:2:5:6-naphthalene tetracarboxylic, 2:21:3:31 - diphenyl tetracarboxylic, 2:2 - bis - (3:4 - dicarboxyphenyl) propane, bis - (3:4 - dicarboxyphenyl) sulphone, perylene 3:4:9:10-tetracarboxylic acid, bis - (3:4 - dicarboxyphenyl) ether, bis - (3:4 - dicarboxyphenyl) sulphone and ethylene tetracarboxylic acid dianhydride.ALSO:A process for the production of an electrically insulating coating comprises depositing a film of a varnish made by reacting one or more diamines with one or tetracarboxylic acid dianhydrides in the presence of one or more non-aqueous, polar organic liquids which are inert to the reactants under the reaction conditions and which are solvents for at least one of the reactants and for the reaction product at a temperature below 60 DEG C. (see Division C3) on a base and thermally or chemically treating the film to convert the polyamide acid or acids to polyimide(s).  In the examples, copper wire is coated in a horizontal varnishing furnace operated at 500 DEG C. with solutions comprising N=N-dimethyl acetamide N-methyl 1-2-pyrrolidene and (1) the reaction product of pyromellitic dianhydride and 4=41-diphenylol-propane-2=21-di-(p-aminophenyl) ether; (2) pyromellitic dianhydride and hydroquinone-di (p-aminophenyl) ether and (3) pyromellitic dianhydride and 4=41-dihydroxydiphenyl ether-di-(p-aminophenyl) ether.