BARRIER COATING COMPOSITIONS AND METHOD OF USE
Provided is a composition that includes a wax combined with a nanocellulose. The composition can be applied to a substrate leading to a better wax coverage with reduced porosity that provides for improved oil, grease, gas, water, and water vapor barrier properties to the coated articles.
1 . A coating composition comprising:
a wax; a nanocellulose chosen from microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and combinations thereof; and water.
2 . The coating composition according to claim 1 , wherein the nanocellulose has a BET surface area of at least about 80 m 2 /g, or at least about 100 m 2 /g.
3 . The coating composition according to claim 1 , wherein the nanocellulose has a xyloglucan absorption at 20° C. of at least 100 mg xyloglucan/(g nanocellulose), or at least 120 mg xyloglucan/(g nanocellulose).
4 . The coating composition according to claim 1 , wherein the nanocellulose has a viscosity of a 1.0 wt. % cellulose suspension is at least 300 cps (at 100 s −1 , 20° C.), and/or total fines of at least 60%.
5 . The coating composition according to claim 1 , wherein the aspect ratio of nanocellulose is greater than 5:1, or greater than 50:1.
6 . The coating composition according to claim 1 , wherein the average fiber width of the nanocellulose is below 1 micron, or below 0.1 micron.
7 . The coating composition according to claim 1 , wherein the nanocellulose is in suspension or paste form prior to combining with the wax.
8 . The coating composition according to claim 1 , wherein the nanocellulose comprises from about 0.1 wt. % to about 2.0 wt. %, or from about 0.4 wt. % to about 1.0 wt. % of the total coating composition.
9 . The coating composition according to claim 1 , optionally comprising thermoplastic polymeric materials.
10 . The coating composition according to claim 9 , wherein the thermoplastic polymeric material is chosen from hydrocarbon resins, polypropylene and propylene copolymer, polyethylene and ethylene copolymer, polystyrene and styrene copolymers, polyester, styrene-maleic anhydride copolymer, derivatives, and combinations thereof.
11 . The coating composition according to claim 1 , further comprising starches, celluloses, lignins, hemicelluloses, pectins, proteins, rosins, alginates, xanthan gum, soy lecithin, lipids, disaccharides, monosaccharides, their derivatives, and combinations thereof.
12 . The coating composition according to claim 1 , wherein the wax is in the form of a dispersion or a solid prior to combining with the nanocellulose.
13 . The coating composition according to claim 1 , wherein the wax is chosen from paraffins, microcrystalline, Fischer-Tropsch, polyethylenes, polypropylenes, montan, palm, palm kernel, coconut, rapeseed, soybean, sunflower, castor, carnauba, beeswax, shellac, candelilla, sugar cane, rice bran, stearates, laurates, oleates, alkyl ketene dimer (AKD), silicone, ethylene bis(stearamide), ethylene-vinyl acetate copolymer (EVA), ethylene-propylene copolymer, and combinations thereof.
14 . A substrate having improved barrier properties comprising:
a substrate; and a coating layer disposed on and in direct contact with the surface of the substrate;
wherein the coating layer comprises a wax; and a nanocellulose chosen from microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and combinations thereof.
15 . The substrate according to claim 14 , wherein the substrate is chosen from paper, paperboard, fiber, molded fibers, fibrils, cellulose fiber, regenerated cellulose, aramid, glass, carbon, polyester, wool, silk, and combinations thereof.
16 . The substrate according to claim 14 , wherein the substrate is a three-dimensional (3D) structure of fibers and/or fibrils, wherein the fibers and/or fibril form a network containing air voids.
17 . The substrate according to claim 14 , wherein the composition reduces the porosity of the substrate by about 50%, or about 75%, or up to about 100%, when compared with an uncoated substrate.
18 . A method of providing improved barrier properties to a substrate comprising:
a) providing a substrate;
b) disposing on the surface of the substrate a coating composition according to claim 1 , wherein the composition is disposed on and in direct contact with at least one surface of the substrate.
19 . The method according to claim 18 , wherein the substrate is composed of fibers and/or fibrils having a 3D structure containing air voids; and wherein the coating composition when disposed on the surface of the substrate fills the air voids in the 3D structure.