Graft copolymers having anhydride functionality

A curable composition which comprises:

• (a) an anhydride-functional polymer;
• and
• (b) an acid-functional compound having an average of at least two carboxylic acid groups per molecule;
• and
• (c) an epoxy-functional compound;
• wherein the anhydride-functional polymer is obtained by reacting under graft copolymerization conditions,
• (A) an unsaturated polymer which was obtained by reacting under ene reaction conditions a mixture of reactants comprising:
• (i) 20 to 70 percent by weight of an unsaturated anhydride having the structure:
• ##STR6## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen;
• and
• (ii) 30 to 80 percent by weight of at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds;
• and
• (B) at least one ethylenically unsaturated monomer which is copolymerizable with the unsaturated polymer.

In a substrate coated with a multi-layer decorative and/or protective coating which comprises:

• (a) a basecoat comprising a pigmented film-forming polymer;
• and
• (b) a transparent clearcoat comprising a film-forming polymer applied to the surface of the basecoat composition;
• the improvement which comprises utilizing as the clearcoat and/or the basecoat a multi-component curable composition which is reactive upon mixing of the components, wherein the multi-component curable composition comprises (a) an anhydride functional polymer and (b) a compound having an average of at least two functional groups per molecule which are reactive with anhydride groups;
• wherein the anhydride-functional polymer is obtained by reacting under graft copolymer conditions,
• (A) an unsaturated polymer which was obtained by reacting under ene reaction conditions a mixture of reactants comprising:
• (i) 20 to 70 percent by weight of an unsaturated anhydride having the structure:
• ##STR7## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen;
• and
• (ii) 30 to 80 percent by weight of at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds;
• and
• (B) at least one ethylenically unsaturated monomer which is copolymerizable with the unsaturated polymer.

In a substrate coated with a multi-layer decorative and/or protective coating which comprises:

• (a) a basecoat comprising a pigmented film-forming polymer;
• and
• (b) a transparent clearcoat comprising a film-forming polymer applied to the surface of the basecoat composition;
• the improvement which comprises utilizing as the clearcoat and/or the basecoat a multi-component curable composition which is reactive upon mixing of the components, wherein the multi-component curable composition comprises:
• (a) an anhydride-functional polymer;
• and
• (b) an acid-functional compound having an average of at least two carboxylic acid groups per molecule;
• and
• (c) an epoxy-functional compound;
• wherein the anhydride-functional polymer is obtained by reacting under graft copolymerization conditions,
• (A) an unsaturated polymer which was obtained by reacting under ene reaction conditions a mixture of reactants comprising:
• (i) 20 to 70 percent by weight of an unsaturated anhydride having the structure:
• ##STR8## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen;
• and
• (ii) 30 to 80 percent by weight of at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds;
• and
• (B) at least one ethylenically unsaturated monomer which is copolymerizable with the unsaturated polymer.

A method of using a anhydride-functional graft copolymer as a crosslinker, which method comprises admixing the anhydride-functional graft copolymer with a compound having an average of at least two functional groups per molecule which are reactive with anhydride groups and allowing the anhydride-functional graft copolymer and the compound to react;

• wherein the anhydride-functional graft copolymer has an average of at least two anhydride groups per molecule and comprises the polymer obtained by reacting under graft copolymerization reaction conditions,
• (A) an unsaturated polymer which was obtained by reacting under ene reaction conditions a mixture of reactants comprising:
• (i) 20 to 70 percent by weight of an unsaturated anhydride having the structure:
• ##STR9## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen;
• and
• (ii) 30 to 80 percent by weight of at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds;
• and
• (B) at least one ethylenically unsaturated monomer which is copolymerizable with the unsaturated polymer.

A process for preparing an anhydride-functional polymer which process comprises:

• (a) obtaining an unsaturated anhydride-functional polymer by admixing under ene reaction conditions:
• (i) 20 to 70 percent by weight of an unsaturated anhydride having the structure:
• ##STR10## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen;
• and
• (ii) 30 to 80 percent by weight of at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds;
• and
• (b) graft copolymerizing the unsaturated polymer with at least one ethylenically unsaturated monomer.