Patent GB-1043098-A (GB)
Title: Process for the manufacture of thermohardening synthetic resins
IPC: C08G73/16
Filed: 1964-11-16
Abstract: A thermosetting resin is prepared by condensing a polycarboxylic acid containing at least 10% by weight of one cyclic tetracarboxylic anhydride or the corresponding acid with an excess of at least one dihydric alcohol, and thereafter condensing the product with at least one primary polyamine.  The preferred tetracarboxylic anhydride is pyromellitic anhydride. Others suitable are 1,5,6,8-naphthalene tetracarboxylic anhydride and o,o1-tetracarboxylic acid di-anhydrides of compounds containing two benzene rings.  Tricarboxylic acids or their anhydrides of compounds containing two benzene rings. Tricarboxylic acids or their anhydrides may also be present, and up to 2 mols. per mol. of tetracarboxylic acid of an amino-alcohol, e.g. ethanolamine.  The dihydric alcohol may be, e.g. ethylene, propylene, butylene or trimethylene glycol, and may include small amounts of monohydric alcohols of not more than 6 C atoms, e.g. butanol or hexanol, or polyhydric alcohols containing more than two hydroxy groups, e.g. glycerol or trimethylol-propane.  The primary polyamines are preferably diamines, e.g. ethylene diamine, hexamethylene diamine, or 4,41-dicyclohexane diamine, more preferably aromatic diamines, e.g. diaminodiphenyl-methane, -ketone, -sulphone, -ether, or -thioether or phenylene- or toluylene-diamines, or condensates of formaldehyde with aniline or aromatic diamines. Other components may be introduced with the polyamine in the second stage of the preparation, notably primary monoamines and cyclic dicarboxylic acid anhydrides, each containing a further group capable of participating in the formation of the resin. Examples of these are aminoalcohols, e.g. ethanolamine and propanolamine, and aminocarboxylic acids, e.g. aminopropionic, aminocaproic and aminobenzoic acids, and tricarboxylic anhydrides, e.g. hemimellitic or trimellitic acid. Polyhydroxy compounds, e.g. ethylene glycol, glycerol and pentaerythritol, and dicarboxylic acids and lower alkyl esters thereof, e.g. iso- and tere-phtalic acids, and dimethyl terephthalate, may also be introduced in the second stage.  The polyamines are preferably used in amounts providing one amino equivalent per equivalent o the tetracarboxylic acid or anhydride, though lower amounts, preferably not less than 75% of this, and higher amounts, preferably providing not more than one amino equivalent per equivalent of tetracarboxylic acid plus any other free acid groups, may be used.  The polyamine may be condensed with any other components of the resin to be added at the second stage, before being condensed with the polyester from the first stage. When the tetracarboxylic acid or anhydride is the sole polycarboxylic acid component, it is particularly desirable that esterification should be as complete as possible, and up to 6 mols. of glycol per mol. of acid may be used to achieve this.  In examples, condensates of pyromellitic anhydride with ethylene glycol, with and without trimellitic anhydride (Example 3), or ethanolamine (Examples 6, 7) are reacted with condensates of 4,41-diaminodiphenylmethane with trimellitic acid, with and without ethylene glycol (Examples 2, 3, 7), or ethanolamine and pyrocarboxylic acid (Example 4), in cresol solution in the presence of antimony trioxide and tin oxalate.  The product solutions are diluted with, e.g. cresol, solvent naphtha and xylene, and are used to coat copper wire, or aluminium.ALSO:Electrical conductors e.g. copper wire or aluminium may be coated, from solution, with a polyesterimide prepared by condensing a polycarboxylic acid containing at least 10 weight % of a cyclic tetracarboxylic anhydride or the corresponding acid with excess dihydric alcohol, then with a primary polyamine (see Division C3).  Suitable solvents are cresol, solvent naphtha, and xylene.  In Examples copper wire is coated in a horizontal wire-enamelling oven using a felt covered roller.