FIELD OF THE DISCLOSURE

The instant disclosure relates to aqueous matte coating compositions and methods for applying aqueous matte coating compositions to substrates. In particular, this disclosure relates to aqueous matte coating compositions comprising acrylic beads and slip additives. The disclosed aqueous matte coatings can be used in, for example, packaging applications. The disclosed compositions and methods provide for matte finishes with better color fidelity, enhanced abrasion resistance, soft touch response, and lower coefficient of friction.

BACKGROUND AND SUMMARY OF THE DISCLOSURE

Matte finishes are commonly used in packaging applications (e.g., food packaging applications) to alter the functionality and/or appearance of the packaging. For example, matte finishes can enhance a packaging's optical appearance, touch or tactile response, ink and image protection for direct printing, processability, etc. Currently, most matte finishes are formulated from inorganic fillers, such as silica, with acrylic and/or polyurethane binders, either solvent-borne or waterborne. However, existing matte finishes exhibit low color fidelity and weak abrasion resistance in, e.g., both gravure and flexographic printing application areas.

Recently, matte finishes incorporating polyurethane beads have addressed soft touch, color fidelity and abrasion resistance issues encountered by previous matte finishes. However, polyurethane beads are relatively expensive and have heat seal resistance concerns. Even more recently, matte finishes including acrylic beads and aminosilanes have been used to address the issues noted above. However, even the incorporation of these acrylic beads and aminosilanes have not fully addressed the unmet needs of customers. Accordingly, aqueous matte coating compositions providing for better color fidelity, enhanced abrasion resistance, soft touch response, and lower coefficient of friction are desirable.

The instant disclosure relates to aqueous matte coating compositions and methods for applying aqueous matte coating compositions to substrates. In particular, this disclosure relates to aqueous matte coating compositions comprising acrylic beads and slip additives. In some embodiments, the compositions comprise a first acrylic bead, a second acrylic bead, a polymer binder, and/or a slip additive. In some embodiments, the first acrylic bead accounts for from 10 to 65 wt %, based on the weight of the coating composition, and has a calculated glass transition temperature (“Tg”) of from −30 to 10° C. and average particle diameter of from 0.1 to 2 μm. All weight percentages described herein refer to weight calculated on a dry-weight basis. In some embodiments, the second acrylic bead accounts for from 20 to 80 wt %, based on the weight of the coating composition, and has a calculated Tgof from −60 to 0° C. and an average particle diameter of from 3 to 30 μm. In some embodiments, the polymer binder accounts for from 10 to 30 wt %, based on the weight of the coating composition and has an average particle diameter from 0.03 to 0.5 μm and a calculated Tgof 0 to 30° C. In some embodiments, the slip additive accounts for 0.1 to 20 wt %, based on the weight of the coating composition, and comprises a silicone emulsion and a wax dispersion. In some embodiments, the slip additive comprises a polyurethane dispersion. In some embodiments, the slip additive comprises two or more selected from the group consisting of a silicone emulsion, a wax dispersion, and a polyurethane dispersion. In some embodiments, the slip additive comprises the combination of more than one type of silicone emulsions and more than one wax dispersion, and more than one polyurethane dispersion.

In some embodiments, the methods for applying aqueous matte coating compositions comprise (a) forming the aqueous matte coating composition comprising (i) from 10 to 65 wt %, based on the weight of the coating composition, of a first acrylic bead having a calculated Tgof from −30 to 10° C. and an average particle diameter of from 0.1 to 2 μm, (ii) from 20 to 80 wt %, based on the weight of the coating composition, of a second acrylic bead having a calculated Tgof from −60 to 0° C. and an average particle diameter of from 0.5 to 30 μm, (iii) from 10 to 30 wt %, based on the weight of the coating composition, of a polymer binder having an average particle diameter of from 0.03 to 0.5 μm and a calculated Tgof 0 to 30° C., and (iv) from 0.1 to 20 wt %, based on the weight the coating composition, of a slip additive. The method further comprises (b) applying the aqueous matte coating composition to a substrate and (c) drying, or allowing to dry, the applied aqueous matte coating composition. In some embodiments, the slip additive comprises a silicone emulsion and a wax dispersion. In some embodiments, the slip additive comprises a polyurethane dispersion. In some embodiments, the slip additive comprises two or more selected from the group consisting of a silicone emulsion, a wax dispersion, and a polyurethane dispersion. In some embodiments, the slip additive comprises the combination of more than one type of silicone emulsions and more than one different wax dispersions, and/or more than one polyurethane dispersions. In some embodiments, the matte coating compositions comprise other additives such as rheology modifiers, defoamers, wetting agents, leveling agents, and the like.

In some embodiments, the matte coating compositions are applied with a polyisocyanate crosslinker at a liquid coating-to-crosslinker ratio of from 100:0.1 to 100:5, based on coating weight.

The disclosed aqueous matte coating compositions can be used with, for example, gravure and flexographic printing application processes.

