Blush resistant adhesives used in bottle labeling
View Patent ↗This invention is directed to an improvement in acrylic based adhesives that are particularly suited for use in the application of paper and plastic labels onto glass surfaces, such as in bottle labeling. The base adhesive is comprised of an emulsion polymerized acrylic copolymer having acid functionality, e.g., carboxyl or sulfonic acid functionality; wherein the emulsion polymerization is carried out in the presence of a stabilizer system comprising a polymer containing polymerized units of carboxylic acid. The improvement for enhancing the blush resistance of the adhesive resides in incorporating a long chain crosslinking polyamine or polyamide containing residual amines.
1. In a clear bottle labeling adhesive comprised of an acrylic polymer formed by the emulsion polymerization of at least one alkyl ester of acrylic acid in the presence of a stabilizer system comprised of a polymer containing polymerized units of a carboxylic acid monomer, the improvement in blush resistance of said adhesive which comprises:
addition of from 0.25 to 5 weight parts of a long chain hydrophobic polyamine or a long chain hydrophobic polyamide containing residual amine per 100 weight parts of the acrylic polymer.
2. The bottle labeling adhesive of claim 1 wherein the stabilizer system is comprised of a polymer comprising polymerized units of styrene and acrylic acid.
3. The bottle labeling adhesive of claim 2 wherein the long chain hydrophobic polyamine is selected from the group consisting of an aliphatic polyamine, a cycloaliphatic polyamine, an aromatic polyamine, a methylene bridged cyclohexane diamine, a hydrogenated derivative of methylenedianiline, and a polyether polyamine, wherein the number of carbons in said long chain hydrophobic polyamine is 6 to 25.
4. The bottle labeling adhesive of claim 3 wherein the long chain hydrophobic polyamine is a cycloaliphatic amine selected from the group consisting of cyclohexane diamine, methylcyclohexane diamine, methylene di(4-cyclohexylamine), cyclohexyl propanediamine, and isophorone diamine.
5. The bottle labeling adhesive of claim 3 wherein the long chain hydrophobic polyamide is formed from a long chain polyethylene polyamine and a C 6-20 carboxylic acid.
6. The bottle labeling adhesive of claim 4 wherein the acrylic polymer has from 1 to 2 weight parts isophorone diamine per 100 weight parts of the acrylic polymer.