Biowax emulsions as bio-based barrier coating dispersions

The barrier coating composition of any one of the foregoing claims, wherein said one or more biowax emulsions comprise:

• (a) said one or more biowaxes in an amount ranging from 20-60 wt %, 25-55 wt %, 30-50 wt %, or 35-45 wt %;
• (b) said one or more rosin sizing agents in an amount ranging from 1-12 wt %, 2-10 wt %, 3-8 wt %, or 4-6 wt %;
• (c) said one or more surfactants in an amount ranging from 2-12 wt %, 4-10 wt %, or 6-8 wt %;
• (d) said one or more microcrystalline or paraffinic waxes in an amount ranging from 2-10 wt %, 3-9 wt %, 4-8 wt %, or 5-7 wt %;
• and
• (e) optionally, said one or more long chain fatty acids in an amount ranging from 0.5-6 wt %, 1-5 wt %, or 2-4 wt %.

The barrier coating composition of any of the foregoing claims, wherein said one or more biowax emulsions comprise an inverse phase biowax emulsion formed by:

• (a) combining said one or more biowaxes, said one or more rosin sizing agents, said one or more surfactants, said one or more microcrystalline or paraffinic waxes, and optionally said one or more long chain fatty acids in a reactor and heating, optionally to 70-99° C., 75-98° C., 85-95° C., or 90-95° C., to form an oil-phase;
• (b) adding an amount of hot water to said oil-phase, wherein the hot water is optionally 70-99° C., 75-98° C., 85-95° C., or 90-95° C.;
• (c) emulsifying at 70-99° C., 75-98° C., or 85-95° C., optionally for an amount of time ranging from 0.5-5 h, 0.5-4 h, or 1-3 h;
• (d) homogenizing;
• (e) cooling the resulting inverse phase biowax emulsion to a temperature ranging from 10-35° C., 15-30° C., or 20-25° C., optionally using an ice-water bath, a cooling jacket, or a cooling core;
• and
• (f) optionally adding a biocide.

The barrier coating composition of any one of the foregoing claims, wherein

• (a) said one or more polyacrylate carriers comprise an aqueous polyacrylate dispersion comprising one or more polyacrylate polymers having a weight average molecular weight of 10,000-1,000,000 Da, 100,000-800,000 Da, or 200,000-600,000 Da, wherein said aqueous polyacrylate dispersion has a total dry solids content ranging from 40-60 wt %, 45-55 wt %, or 49-51 wt %,
• (b) said one or more rheology modifiers comprise one or more bio-based gums, including but not limited to, pre-hydrated cellulose gums, xanthan gums, or a mixture thereof, one or more bio-based hydrocolloids, one or more polyacrylate dispersants, including but not limited to polyacrylate dispersants having a charge ranging from 70-100 mol %, 80-100 mol %, or 90-100 mol % and a molecular weight ranging from 1000-100,000 Da, 2000-80,000 Da, or 10,000-50,000 Da, or a combination thereof;
• (c) said one or more auxiliary additives are selected from clay, kaolin, alumina, silica, nano-clay, nanocellulose, nano-structured cellulose, cellulose nanofibers (CNF), nano-fibrillated cellulose (NFC), bacterial nanocellulose, cellulose nanocrystals (CNC), micro-fibrillated cellulose (MFC), and microcrystalline cellulose (MCC), and any combination thereof;
• (d) any combination of (a), (b) and (c).

The barrier coating composition of any one of the foregoing claims, wherein said barrier coating composition comprises:

• (a) said one or more biowax emulsions in an amount ranging from 20-80 wt %, 30-70 wt %, or 40-60 wt %;
• (b) said one or more polyacrylate carriers in an amount ranging from 20-80 wt %, 30-70 wt %, or 40-60 wt %;
• (c) said one or more rheology modifiers in an amount ranging from 0.1-5 wt %, 0.1-4 wt %, or 0.1-3 wt %, further wherein the dosage of said one or more rheology modifiers is modified to achieve a bulk viscosity of the barrier coating composition, in final form of 150-800 cPs;
• and
• (d) said one or more auxiliary additives in an amount ranging from 0-10 wt %, 1-9 wt %, 1-8 wt %, 1-6 wt %, or 1-3 wt % when used as a topcoat, and an amount ranging from 30-70 wt %, 40-60 wt %, 45-55 wt % when used as a basecoat.

The barrier coating composition of any one of the foregoing claims, wherein said barrier coating composition comprises a stable dispersion formed by dispersing, separately or together, said one or more biowax emulsions, said one or more rheology modifiers, and said one or more auxiliary additives into said one or more polyacrylate carriers with mechanical mixing to form said stable dispersion;

• wherein said barrier coating composition, in final form:
• (a) comprises a total solids content ranging from 30-70 wt %, 40-60 wt %, 45-55 wt %, or 48-52 wt %;
• (b) comprises a bio-based solids content ranging from 40-60 wt %, 45-60 wt %, 50-60 wt %, or 55-60 wt % of said total solids content;
• (c) has a particle size ranging from 0.2-5 μm, 1-4 μm, 2-3 μm, or 2.5-3μ m;
• (d) has a bulk viscosity ranging from 40-800 cPs, 100-700 cPs, 150-650 cPs, or 200-400 cPs;
• (e) has a stability greater than 3 months at 25° C., wherein stability is determined by said barrier coating composition maintaining an aged viscosity within ±50%, ±40%, ±30%, or ±20% of said bulk viscosity in (d);
• and
• (f) any combination of one, two, three, four or all five of (a) to (e).

The barrier coating composition of any of the foregoing claims, when applied as one or more coatings to a lignocellulosic substrate, including but not limited to paper, paperboard, cupstock basesheets, bleached sulfate cupstock basesheets, fast food wrapping paper, or 100% recycled linerboard sheets, wherein

• said one or more coatings are formed at room temperature using a conventional paper coater, rolling-coater, or metering size press machine, followed by oven curing at 100-120° C., 105-115° C., or 108-112° C., for 60-120 sec, 70-110 sec, 80- 100 sec, or 90-95 sec results in one or more of the following:
• (a) said barrier coating composition forms a single coat layer, a basecoat layer, a topcoat layer, a double-coating comprising a basecoat layer and a topcoat layer comprising the same barrier coating composition, a double-coating comprising a basecoat layer and a topcoat layer comprising different barrier coating compositions, or multiple coating layers;
• (b) said one or more coatings provides increased paper fiber strength and decreased paper fiber discoloration, compared to a biowax coating applied at a temperature of 60-180° C., 70-170° C., or 80-160° C.;
• (c) said one or more coatings provide a barrier to transmittance of one or more of oil, grease or water into or through said lignocellulosic substrate at temperatures ranging from 5-95° C., 15-90° C., 25-85° C., or 40-60° C., wherein said barrier to transmittance is greater than or equal to one or more coatings formed in the same manner from said polyacrylate carrier alone;
• (d) said one or more coatings, when applied at a coat weight of 10-30, 16-22, or 18-20 grams per square meter (gsm), results in KIT test values (i.e., a measure of oil and grease resistance) and Cobb 30 min test values (i.e., a measure of mass of water absorbed per square meter over 30 min) that are equal to or enhanced (i.e., higher KIT values and lower Cobb values) compared a coating formed in the same manner from said polyacrylate carrier alone;
• (e) said one or more coatings, when applied at a coat weight of 10-30, 16-22, or 18-20 grams per square meter (gsm) displays a coat weight dependent decrease in Cobb 30 min test results;
• and
• (f) said one or more coatings, in final form, comprise a percent bio-based material of ≥50 wt %, 50-65 wt %, 50-60 wt %, or 50-55 wt %.

A method for preparing a barrier coating composition for paper or board, optionally according to any one of the foregoing claims, the method comprising:

• (a) forming at least one biowax emulsion;
• (b) forming or providing one or more polyacrylate carriers;
• (c) dispersing said at least one biowax emulsion into said one or more polyacrylate carriers;
• (d) optionally, dispersing one or more rheology modifiers into said one or more polyacrylate carriers;
• and
• (e) optionally, dispersing one or more auxiliary additives into said one or more polyacrylate carriers;
• wherein steps (c)-(e) are effected together or separately.