Curing agent for aqueous epoxy resin dispersions, process for its preparation and its use

A curing agent for aqueous epoxy resin dispersions comprising:

• (i) about 10 to 80% by weight of at least one emulsifier which includes at least one polyalkylene-polyether-diamine-group represented by the following formula:
• ##STR56## wherein the R.sup.1 groups may be the same or different and each is selected from hydrogen, straight or branched chain alkyl residues having 1-6 carbon atoms, or straight or branched chain alkyl radicals having 1-6 carbon atoms substituted with one or more phenyl residues, the R.sup.4 groups may be the same or different, and each is selected from alkylene groups having 1 to 8 carbon atoms, n is an integer of 1 to 5, and x is an integer of from 8-90, and wherein the group of formula (I) of emulsifier (i) is bonded to a structure of the following formula:
• ##STR57## wherein R.sup.5 is a long chain alkyl residue having 7-25 carbon atoms, or an aliphatic polyamine residue of the following formula:
• ##STR58## wherein R.sup.6 is an alkyl residue having 7-25 carbon atoms, Y is a direct linkage or a bivalent group of formula:
• ##STR59## and z is an integer of 1 to 4;
• B is an alkylene residue, an alkylene residue interrupted in its alkylene chain through one or more ether oxygen atoms, or a bivalent cycloaliphatic, aromatic or araliphatic residue;
• and R.sup.1 is selected from the group of hydrogen, straight or branched chain alkyl residues having 1-6 carbon atoms, or straight or branched chain alkyl residues having 1-6 carbon atoms and which are phenyl substituted;
• (ii) about 1-80% by weight of a coemulsifier comprising at least one polyalkylene polyamine group of the following formula:
• ##STR60## wherein the R.sup.1 group and n are as defined above, and y is an integer of from 1-6, and where in coemulsifier (ii) the polyalkylene-polyamine-group of formula (II) is bonded to a structure of the following formula:
• ##STR61## wherein R.sup.5 is a long chain alkyl residue having 7-25 carbon atoms or an aliphatic polyamine residue of the following formula:
• ##STR62## wherein R.sup.6 is an alkyl residue having 7-25 carbon atoms, Y is a direct linkage or a bivalent group of formula:
• ##STR63## z is an integer of 1 to 4;
• B is an alkylene residue or an alkylene residue interrupted through one or more ether oxygen atoms, or a bivalent cycloaliphatic, aromatic or araliphatic residue;
• and R.sup.1 is selected from the group of hydrogen, straight chain or branched alkyl residues having 1-6 carbon atoms, and phenyl substituted alkyl radicals comprising 1-6 carbon atoms in the alkyl moieties;
• (iii) about 5-80% by weight of at least one bis(diamine)-diepoxide-adduct comprising at least two amino-alcohol groups of the following formula:
• ##STR64## wherein the R.sup.1 groups are as defined above, and A is an alkylene residue, cycloalkylene residue, a polyalkylene-polyether-residue, or a bivalent residue comprising alkyl groups and cycloalkyl and/or aromatic groups, and where in the bis(diamine)-diepoxide adduct (iii) the two groups of formula (III) are bonded to a bivalent structure of the following formula:
• --CH.sub.2 --O--B--O--CH.sub.2 -- (V);
• wherein B is an alkylene residue or an alkylene residue, the carbon chains of which are interrupted through one or more ether oxygen atoms, or a bivalent cycloaliphatic, aromatic or araliphatic residue, and wherein the two groups of formula (III) bonded to said bivalent structure of formula (V), have the same structure, or a different structure.