Salts of pyromellitic acid, and their use as epoxy resin curing agents
AssigneeHuels Aktiengesellschaft
InventorsRainer Gras, Elmar Wolf
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Abstract
The invention relates to salts of pyromellitic acid which comprise 1 mol of pyromellitic acid and 0.5 to 2 mol of a guanidine of the following composition: ##STR1## in which R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are identical or different radicals from the group consisting of hydrogen, alkyl, cycloalkyl and aromatic hydrocarbon residues having 1 to 8 carbon atoms, and R.sup.1 and R.sup.2 and R.sup.3 and R.sup.4 may form a joint ring which may contain an oxygen atom as heteroatom. Also claimed are the preparation of the salts and their use for matt epoxide and hybrid powder coatings.
Claims5
A matt epoxide powder coating comprising an epoxy resin comprising 3 to 12% by weight of a salt of pyromellitic acid which comprises 1 mol of pyromellitic acid and 0.5-2 mol of a guanidine of the formula:
- ##STR5## wherein R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4, identical or different, are each a radical selected from the group consisting of hydrogen, C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl and C.sub.6-8 aromatic hydrocarbon residues, or R.sup.1 and R.sup.2 and R.sup.3 and R.sup.4 may jointly form a ring containing 3 to 8 carbon atoms in which one of the carbon atoms may be replaced with an oxygen atom.
A matt hybrid powder coating comprising an epoxy resin comprising
- (i) 0.5-12% by weight of a salt of pyromellitic acid comprising 1 mol of pyromellitic acid and 0.5-2 mol of a guanidine of the formula:
- ##STR6## wherein R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4, identical or different, are each a radical selected from the group consisting of hydrogen, C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl and C.sub.6-8 aromatic hydrocarbon residues, or R.sup.1 and R.sup.2 and R.sup.3 and R.sup.4 may jointly form a ring which may contain an oxygen atom;
- (ii) a COOH-containing polyester;
- and
- (iii) optionally, an isophorone diisocyanate adduct blocked with .epsilon.-caprolactam.
Dependencies are inferred from the claim text.