Amino-quinones, and their use in providing corrosion resistance to metals

A method for maintaining the specific saturation magnetization of coated iron pigments comprising:

• contacting uncoated iron pigments which have been pretreated by a reduction treatment to reduce iron oxides, with a solution of a copolymer in a solvent capable of dissolving said copolymer, wherein said copolymer is a member selected from the group consisting of:
• (i) copolymers of:
• (A) 3 to 60% by weight, of units derived from one or more reactive aminoquinones of formula I ##STR15## wherein R is hydrogen, branched, linear or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl, or phenyl which may be substituted by linear, branched or cyclic C.sub.1 -C.sub.4 alkyl, --NO.sub.2, F, OR.sup.2, NR.sup.3.sub.2, wherein R.sup.2 and R.sup.3 are linear, branched or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl or phenyl,
• R.sup.1 is a linear, branched or cyclic C.sub.2 -C.sub.18 alkylene chain, phenylene, aralkylene, alkarylene, or --(CH.sub.2 CH.sub.2 --O).sub.n --CH.sub.2 -CH.sub.2 --, wherein n is an integer from 1 to 50,
• X is hydroxy, epoxy, vinyl, vinyloxy, acrylate, methacrylate or acylchloro or of the formula II ##STR16## wherein Y is N or CH R.sup.4 is linear or branched C.sub.1 -C.sub.6 alkyl and X is as defined above, and
• (B) 40 to 97% by weight, of units derived from one or more comonomers having at least one functional group reactive with the reactive aminoquinone of part (A);
• (ii) copolymers of:
• (A1) one or more reactive aminoquinones of formula (IV):
• ##STR17## wherein R is hydrogen, branched, linear or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl, or phenyl which may be substituted by linear, branched or cyclic C.sub.1 -C.sub.4 alkyl, --NO.sub.2, F, OR.sup.2, NR.sup.3.sub.2, wherein R.sup.2 and R.sup.3 are linear, branched or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl or phenyl;
• and
• R.sup.7 is --(CH.sub.2).sub.n --, phenyl (--C.sub.6 H.sub.4 --), --C.sub.6 H.sub.4 --O--C.sub.6 H.sub.4 --, --C.sub.6 H.sub.4 --CO--C.sub.6 H.sub.4 --, --C.sub.6 H.sub.4 --SO.sub.2 --C.sub.6 H.sub.4 --, biphenyl, --CH.sub.2 --C.sub.6 H.sub.4 --CH.sub.2 --, 2,5-tolyl-diyl, 2,4-tolyl-diyl or 2,4-anisyl-diyl;
• wherein n is an integer from 2 to 12;
• and
• (B1) one or more tetracarboxylic dianhydrides;
• and
• (iii) copolymers of:
• (A2) one or more reactive aminoquinones of formula (V):
• ##STR18## wherein R is hydrogen, branched, linear or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl, or phenyl which may be substituted by linear, branched or cyclic C.sub.1 -C.sub.4 alkyl, --NO.sub.2, F, OR.sup.2, NR.sup.3.sub.2, wherein R.sup.2 and R.sup.3 are linear, branched or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl or phenyl;
• and
• R.sup.8 is --O--(CH.sub.2).sub.n --, phenoxy, phenylsulfonyl or a single bond, wherein n is an integer from 2 to 12;
• and
• (B2) one or more diamines;
• under conditions sufficient to provide a coating of said copolymer on an outer surface of said iron particles;
• removing excess copolymer from said outer surface of said iron particles;
• and
• drying said coated iron particles.