Labels

1. A method of producing a printed label, the method comprising:

providing a label substrate having a first surface and a second surface, wherein the first and second surfaces form opposing surfaces of the label substrate;

applying a primer comprising a cross-linkable primer resin onto the first surface of a label substrate to form a primer layer;

electrophotographically printing onto the primer layer an electrostatic ink composition comprising a cross-linkable thermoplastic resin to form a printed layer;

applying a cross-linking composition comprising an epoxy-based cross-linking agent to the printed layer, wherein the epoxy-based cross-linking agent penetrates into the electrostatic ink composition and the primer layer, and wherein the epoxy-based cross-linking agent has the formula:

wherein X is a group including an epoxy group, Y is H or an alkyl; and p is an integer from 0 to 10;

activating the cross-linking agent; and

applying an over print varnish over the cross-linking composition, wherein the over print varnish comprises a polymer having an isocyanurate functionality;

wherein an adhesive is present on the second surface of the label substrate when providing the label substrate, or wherein the adhesive is subsequently applied to the second surface of the label substrate at any point in the method.

2. The method according to claim 1 , wherein the cross-linkable primer resin comprises a carboxylic functional group, an amine functional group or a polyol functional group.

3. The method according to claim 1 , wherein the cross-linkable thermoplastic resin comprises a resin selected from the group consisting of alkylene acrylic acid resins, alkylene methacrylic acid resins, polyurethane resins, polyethylene imine resins, polyamide resins, polyvinyl alcohol, a polymer having acidic side groups, and combinations thereof.

4. The method according to claim 1 , wherein the electrostatic ink composition is a liquid electrostatic ink composition.

5. The method according to claim 1 , wherein the cross-linking composition does not contain any cross-linkable resin.

6. The method according to claim 1 , wherein the cross-linking composition consists essentially of from 0.5 wt % to 30 wt % cross-linking agent by total weight of the cross-linking composition and from 70 wt % to 99.5 wt % carrier solvent.

7. The method according to claim 1 , wherein the label substrate comprises paper and/or a polymeric film.

8. The method according to claim 1 , wherein the adhesive is a pressure-sensitive adhesive, a heat-sensitive adhesive, a contact adhesive, a drying adhesive, a radiation-curing adhesive, or a moisture-curing adhesive.

9. The method according to claim 1 , wherein the over print varnish is applied-after the activation of the cross-linking agent.

10. The method according to claim 1 , wherein the over print varnish is applied after the application of the cross-linking composition and before the activation of the cross-linking agent.

11. The method according to claim 1 , wherein the adhesive includes rubber-based hot melt composition or a solvent rubber adhesive.

12. The method according to claim 1 , wherein the label substrate includes an acrylic substrate.