Patent GB-1076722-A (GB)
Title: Improvements in silylated polyamide acid resins and polyimides derived therefrom
IPC: H01B3/30
Filed: 1965-04-14
Abstract: A polymer composed of the recurring unit <FORM:1076722/C3/1> is prepared by reacting, in a solvent for at least one of the reactants and for the silylated polyamide acid resin thereby obtained, a silylated diamine of the formula <FORM:1076722/C3/2> with at least one tetracarboxylic acid dianhydride of the formula <FORM:1076722/C3/3> wherein Z is a monovalent hydrocarbon radical, R is a tetravalent radical containing at least 6 carbon atoms in a ring having benzenoid unsaturation, the four carbonyl groups being attached to separate carbon atoms in the ring, and each pair of -NH-CO- and -CO2SiZ3 substituents shown in the first formula on the right and left of R respectively being attached to adjacent carbon atoms in the R radical, R1 is a divalent aromatic radical of at least 6 carbon atoms and X is an integer greater than 1.  Preferred solvents are dioxane, tetrahydrofuran, tetrahydropyran or a mixture of N-methylpyrrolidone with any one of the above solvents or with a mixture of alkylated benzenes, toluene and acetonitrile. Dianhydrides exemplified are pyromellitic dianhydride and benzophenone tetracarboxylic acid dianhydride, but many others are specified. Suitable silylated diamines are N,N1-bis(trimethylsilyl)-p,p1-diaminodiphenyl ether, N,N1-bis(trimethylsilyl)-m - phenylene diamine, N,N1 - bis(trimethylsilyl) - p - phenylenediamine and N,N1 - bis (trimethylsilyl) - p,p1 - diaminodiphenylmethane. The silylated polyamide acid resins on heating split off the triorganosiloxy group as either the triorganosilanol or the hexaorganosiloxane, with the concurrent formation of the polyimide resin.  The triorganosilyl diamines can be prepared by reacting a diamine of the formula H2N-R1-NH2 with a triorganosilane of the formula Z3SiX, where R1 and Z have the meanings given above and X is a halogen atom.  At least 2 and up to 6 moles of the silane may be reacted with 1 mol. of the diamine preferably in the presence of a solvent such as benzene, toluene, xylene or dioxane and a hydrohalide acceptor such as pyridine, triethylamine or other tertiary amine. Preparations of the silylated diamines specified in the paragraph above are exemplified.ALSO:Electrical conductors e.g. copper and aluminium may be coated with a solution in a suitable solvent of a polyamide acid resin having recurring units of the formula:  <FORM:1076722/B1-B2/1> wherein Z is a monovalent hydrocarbon radical, R is a tetravalent radical containing at least 6 carbon atoms in a ring having benzenoid unsaturation, the four carbonyl groups being attached to separate carbon atoms in the ring, and each pair of -NHCO- and -CO2 SiZ3 substituents shown in the formula on the right and left of R respectively being attached to adjacent carbon atoms in the R radical, R1 is a divalent aromatic radical of at least 6 carbon atoms, and X is an integer greater than 1.  The coated conductor may then be passed through a heated tower at 150 DEG C to 350 DEG C to convert the silylated polyamide acid resin to the corresponding polyimide resin with volatilization of the solvent and the triorganosilanol.