Patent GB-868465-A (GB)
Title: Improvements in or relating to polyester varnish resins
IPC: C07F15/06
Filed: 1958-07-18
Abstract: In the manufacture of polyester varnish resins, suitable for insulating electric conductor wires, by heating a polyhydric alcohol with an aromatic polycarboxylic acid (or an anhydride or monohydric alcohol ester thereof), reaction is effected in the presence of a catalyst which is soluble in the reaction mixture and consists of a complex of (a) an oxide or inorganic salt of a metal which is at least divalent, (b) a carboxylic acid or a phenol, and (c) a primary mono-amine or a polyamine containing at least two primary amino groups; the reaction mixture being heated to a temperature at which the complex is gradually decomposed. The amine liberated reacts with the polyesterification product, and may promote cross-linking during the subsequent baking.  The complex used may have the formula: <FORM:0868465/IV (a)/1> in which Me=Zn, Cd, Mg, Ca, Cu, Pb, Sn, Cr, Mn, Fe, Co or Ni; X1 and X2 are monovalent aryl or acyl groups or together represent a divalent arylene group; R1 and R2 are aliphalic, cycloaliphalic or aromatic hydrocarbon groups; and R is an alkylene group which may be interrupted by at least one -NH group. Polyesterification may be effected in the presence of a resin which is cured by the amine liberated by decomposition of the complex, e.g. a phenolic or an epoxy resin.  Such resins may first be partially reacted with the metal complex and the product added to the polyesterification mixture at the beginning or towards the end of the reaction.  If the added resin is an epoxy resin, it may be partially reacted with a hardening agent before adding it to the polyesterification mixture.  In the manufacture of the polyester, suitable polyhydric alcohols are ethylene glycol, diethylene glycol, glycerol, hexanetriol and pentaerythritol or mixtures of ethylene glycol and glycerol whilst suitable polycarboxylic acids are phthalic, isophthalic, terephthalic and naphthalic acids.  In examples polyesters were made by reacting dimethyl terephthalate, ethylene glycol and glycerol in the presence of (1) a complex of lead oxide, cresol and diethylene triamine; (2) a complex of copper sulphate, cresol and ethylene diamine; (3) a complex of zinc oxide, cresol and tetraethylene pentamine; (4) a reaction product of an epoxy resin and the complex of Example 1; (5) the complex of Example 1 followed later by the complex of Example 4; (6) the complex of Example 2 followed later by the partial reaction product of an epoxy resin and phthalic anhydride; (7) a complex of zinc oxide, isocaprylic acid and diethylene triamine.  All of the products were dissolved in cresol to form a varnish.ALSO:Metal complexes, used as polyesterification catalysts (see Group IV(a)), are made by reacting (a) an oxide or inorganic salt of a metal which is at least divalent with (b) a phenol or a carboxylic acid and reacting the product with (c) a primary mono-amine or a polyamine containing at least two primary amino groups.  The complexes may have the formula: <FORM:0868465/IV (b)/1> wherein Me is Zn, Cd, Mg, Ca, Cu, Pb, Sn, Cr, Mn, Fe, Co or Ni; X1 and X2 are monovalent aryl or acyl groups or together represent a divalent arylene group; R1 and R2 are aliphatic, cycloaliphatic or aromatic hydrocarbon groups; and R is an alkylene radical which may be interrupted by one or more -NH groups.  The Specification lists suitable reactants falling within the classes (a), (b), and (c) above.  In examples, complexes are formed from (1) lead oxide, cresol and diethylene triamine; (2) copper sulphate, cresol and ethylene diamine; (3) zinc oxide, cresol and tetraethylene pentamine; (7) zinc oxide, iso caprylic acid and diethylene triamine.