Cellulose esters moidified with anhydrides of dicarboxylic acids and their use in waterborne basecoats

A process for coating a substrate, the process comprising the steps of:

• A. Making a thermosetting coating composition comprising a cellulose mixed ester having a number average molecular weight of between 5,000 and 100,000, and reactive components comprising a crosslinker having at least two functional sites capable of reacting during curing of the coating, wherein the cellulose mixed ester comprises:
• i. a first residue that is a residue of a cyclic dicarboxylic acid anhydride, present in an amount of from 3 to 35 weight percent of the cellulose ester;
• ii. a second residue that is at least one member selected from the group consisting of:
• a. an oleophilic monocarboxylic acid residue that is at least one member selected from the group consisting of residues of monocarboxylic acids having at least 3 carbon atoms, wherein the oleophilic monocarboxylic acid residue is present in an amount of from 10 to 65 weight percent of the cellulose ester;
• b. a hydrophilic monocarboxylic acid residue that is a residue of acetic acid, wherein the hydrophilic monocarboxylic acid residue is present in an amount of from 1 to 45 weight percent of the cellulose ester, wherein a degree of substitution within the cellulose mixed ester is from 2 to 3,
• B. applying the coating composition to a substrate so that an uncured coating is formed, and
• C. baking the uncured coating, whereby a cured coating is formed.

A coated substrate, wherein the coating comprises at least one coating layer comprising a flake pigment at least one member selected from the group consisting of:

• A. a condensation product formed by the reaction of a cellulose mixed ester having a number average molecular weight of between 5,000 and 100.000, with a crosslinker having at least two functional sites, wherein the cellulose mixed ester comprises:
• i. a first residue that is a residue of a cyclic dicarboxylic acid anhydride, present in an amount of from 3 to 35 weight percent of the cellulose ester;
• ii. a second residue, wherein the second residue is at least one member selected from the group consisting of:
• a. an oleophilic monocarboxylic acid residue, that is at least one member selected from the group consisting of residues of monocarboxylic acids having at least 3 carbon atoms, wherein the oleophilic monocarboxylic acid residue is present in an amount of from 10 to 65 weight percent of the cellulose ester;
• b. a hydrophilic monocarboxylic acid residue that is a residue of acetic acid, wherein the hydrophilic monocarboxylic acid residue is present in an amount of from 1 to 45 weight percent of the cellulose ester,
• wherein a degree of substitution within the cellulose mixed ester is from 2 to 3, and
• B. a cellulose mixed ester, wherein the cellulose mixed ester comprises:
• i. a first residue that is a residue of a cyclic dicarboxylic acid anhydride, present in an amount of from 3 to 35 weight percent of the cellulose ester;
• ii. a second residue, wherein the second residue is at least one member selected from the group consisting of:
• a. an oleophilic monocarboxylic acid residue that is at least one member selected from the group consisting of residues of monocarboxylic acids having at least 3 carbon atoms, wherein the oleophilic monocarboxylic acid residue is present in an amount of from 10 to 65 weight percent of the cellulose ester;
• b. a hydrophilic monocarboxylic acid residue that is a residue of acetic acid, wherein the hydrophilic monocarboxylic acid residue is present in an amount of from 1 to 45 weight percent of the cellulose ester,
• wherein a degree of substitution within the cellulose mixed ester is from 2 to 3.